U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

OCS EIS/EA

BOEM 2016-018

Gulf of Mexico OCS 

Oil and Gas Lease Sales: 2017-2022

Gulf of Mexico Lease Sales 249, 250, 251, 252, 253, 

254, 256, 257, 259, and 261

Draft Environmental Impact Statement

Volume I: Chapters 1-4 

U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

OCS EIS/EA

BOEM 2016-018

Gulf of Mexico OCS 

Oil and Gas Lease Sales: 2017-2022

Gulf of Mexico Lease Sales 249, 250, 251, 252, 253, 

254, 256, 257, 259, and 261

Draft Environmental Impact Statement

Volume I: Chapters 1-4 

Author

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

Published by

New Orleans

April 2016



v 

COVER SHEET

Environmental Impact Statement 

for 

Proposed Gulf of Mexico OCS Oil and Gas 

Lease Sales 249, 250, 251, 252, 253, 254, 256, 257, 259, and 261

Draft (x) Final ( )

Type of Action: Administrative (x) Legislative ( )

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

Texas, Louisiana, Mississippi, Alabama, and northwestern Florida

Agency 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

Mary Cody

U.S. Department of the Interior

Bureau of Ocean Energy Management

45600 Woodland Road (VAM-OEP) 

Sterling, VA 20166-9216

703-787-1584

Helen Rucker

504-736-2421

Gary Goeke

504-736-3233

ABSTRACT

This Draft Multisale Environmental Impact Statement (EIS) covers the proposed 2017-2022

Gulf of Mexico’s OCS oil and gas lease sales as scheduled in the Proposed Outer Continental Shelf 

Oil & Gas Leasing Program: 2017-2022 (Five-Year Program). The 10 proposed Region-wide lease 

sales are Lease Sale 249 in 2017, Lease Sales 250 and 251 in 2018, Lease Sales 252 and 253 in 

2019, Lease Sales 254 and 256 in 2020, Lease Sales 257 and 259 in 2021, and Lease Sale 261 in 

2022.

The proposed actions are major Federal actions requiring an EIS. This document provides 

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

implementing regulations, and it will be used in making decisions on the proposals. This document 

includes the purpose and background of the proposed actions, identification of the alternatives, 

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

the proposed actions, alternatives, and associated activities, including proposed mitigating measures 

and their potential effects. Potential contributions to cumulative impacts resulting from activities 

associated with the proposed actions are also analyzed.
vi 

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

oil spills), and potential impacts that might result if the proposed actions are adopted. Activities and 

disturbances associated with the proposed actions on biological, physical, and socioeconomic 

resources are considered in the analyses. 

This Draft Multisale EIS analyzes the potential impacts of the proposed actions on air and 

water quality, coastal habitats, deepwater benthic communities, Sargassum, live bottom habitats, 

fishes and invertebrates, birds, protected species, commercial and recreational fisheries, 

recreational resources, archaeological resources, human resources, and land use. It is important to 

note that this Draft Multisale 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, was either 

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

methodologies were applied in its place.

Additional copies of this Draft Multisale EIS 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, New Orleans, Louisiana 

70123-2394, by telephone at 504-736-2519 or 1-800-200-GULF, or on the Internet at 

http://www.boem.gov/nepaprocess/. 
Executive Summary vii

EXECUTIVE SUMMARY

PURPOSE OF AND NEED FOR THE PROPOSED ACTIONS

The Bureau of Ocean Energy Management 

(BOEM) proposes to conduct 10 regionwide Gulf of 

Mexico (GOM) oil and gas lease sales, which are 

tentatively scheduled in the Proposed Outer 

Continental Shelf Oil & Gas Leasing Program: 

2017-2022 (Five-Year Program; USDOI, BOEM, 

2016a). Five regionwide lease sales are tentatively 

scheduled in August of each year from 2017 through 

2021 and five regionwide lease sales are tentatively 

scheduled in March of each year from 2018 through 

2022. The lease sales proposed in the GOM in the Five-Year Program are regionwide lease sales 

comprised of the Western, Central, and a small portion of the Eastern Planning Areas (WPA, CPA, 

and EPA, respectively) not subject to Congressional moratorium (Figure 1). Even though the FiveYear Program includes regionwide lease sales, any individual lease sale could still be scaled back 

during the prelease sale process to conform more closely to the separate planning area model used 

in the Proposed Final Outer Continental Shelf Oil & Gas Leasing Program: 2012-2017 (2012-2017 

Five-Year Program; USDOI, BOEM, 2012a), should circumstances warrant.

Figure 1. Proposed Regionwide Lease Sale Area Combining the Western, Central, and 

Eastern Planning Areas.

The proposed lease sales would provide qualified bidders the opportunity to bid upon and 

lease acreage in the Gulf of Mexico Outer Continental Shelf (OCS) in order to explore, develop, and 

produce oil and natural gas.

Proposed 2017-2022 

Gulf of Mexico OCS Region 

Lease Sale Schedule

Lease Sale Number Year

249 2017

250 and 251 2018

252 and 253 2019

254 and 256 2020

257 and 259 2021

261 2022
viii Gulf of Mexico Multisale EIS

“It is hereby declared to be the 

policy of the United States that . . . 

the Outer Continental Shelf is a 

vital national resource held by the 

Federal Government for the public, 

which should be made available for 

expeditious and orderly 

development, subject to 

environmental safeguards, in a 

manner which is consistent with 

the maintenance of competition 

and other national needs."

OCSLA, 43 U.S.C. §§ 1331 et seq.

Purpose of the Proposed Actions

The Outer Continental Shelf Lands Act of 1953, as 

amended (43 U.S.C. §§ 1331 et seq. [1988]), hereafter 

referred to as OCSLA, establishes the Nation’s policy for 

managing the vital energy and mineral resources of the 

OCS. Section 18 of OCSLA requires the Secretary of the 

Interior to prepare and maintain a schedule of proposed 

OCS oil and gas lease sales determined to “best meet 

national energy needs for the 5-year period following its 

approval or reapproval” (43 U.S.C. § 1344). The Five-Year 

Program establishes a schedule that the U.S. Department 

of the Interior (USDOI or DOI) will use as a basis for 

considering where and when leasing might be appropriate 

over a 5-year period.

The purpose of the proposed Federal actions is to 

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

accordance with the OCSLA.

Need for the Proposed Actions

The need for the proposed actions is to further the orderly development of OCS resources in 

an environmentally and economically responsible manner. Oil serves as the feedstock for liquid 

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

from the Gulf of Mexico OCS contributes to meeting domestic demand and enhances national 

economic security.

THE DECISION TO BE MADE

BOEM will make an individual decision on whether and how to proceed with each proposed 

lease sale in the Five-Year Program. After completion of this Multisale EIS, BOEM will make a 

decision on proposed Lease Sale 249 (i.e., prepare a Record of Decision for Lease Sale 249 only). 

As discussed in Chapter 1.3.1, individual decisions will be made on each subsequent lease sale 

after completion of the appropriate supplemental NEPA documents.

SCOPING

BOEM conducted a public scoping process that extended from April 29 to June 1, 2015. 

Public scoping meetings were held in five cities (New Orleans, Louisiana; Houston, Texas; Panama 

City, Florida; Mobile, Alabama; and Gulfport, Mississippi). In addition to accepting oral and written 

comments at each public meeting, BOEM accepted written comments by mail, email, and through 

the regulations.gov web portal (http://www.regulations.gov). BOEM received a total of 10 comments 

in response to the Notice of Intent to Prepare an EIS. Many of the comments cited broad 

environmental concerns or specific concern about impacts on marine wildlife in general or on 
Executive Summary ix

protected species such as marine mammals and sea turtles. Others cited concerns about impacts to 

critical habitats, fish and fisheries, sensitive benthic communities, and pelagic resources. Several of 

the comments had concerns with the effects of oil spills and the safety of offshore operations. Within 

the broad category of socioeconomics, comments focused on impacts on fisheries, recreation, 

tourism, and local jobs. Some of the comments provided recommendations for inclusion of particular 

alternatives or mitigation in this Multisale EIS analysis. Some comments recommended the 

implementation of specific analysis methodologies, while others recommended that recent industry 

technology and safety advances be taken into consideration.

Pursuant to the OCSLA, the Bureau of Ocean Energy Management published a Call for 

Information (Call) to request and gather information to determine the Area Identification (Area ID) for 

each lease sale. The Call was published in the Federal Register (2015a) on September 4, 2015. 

The Call invited potential bidders to nominate areas of interest within the program area(s) included in 

the 2017-2022 Draft Proposed Program. The Call was also an opportunity for the public to provide 

information on environmental, socioeconomic, and other considerations relevant to determining the 

Area ID. The comment period for the Call closed on October 5, 2015. BOEM received one 

comment letter in response to the Call from the Louisiana Department of Natural Resources. The 

Louisiana Office of Coastal Management requested that BOEM consider secondary and cumulative 

impacts of OCS lease sales on coastal environments as well as identify, quantify, and mitigate (e.g., 

compensatory mitigation) secondary and cumulative harm that occurs to Louisiana’s coastal 

wetlands, and implement plans for validating predictions of social and environmental effects on 

coastal resources. Using information provided in response to the Call and from scoping comments, 

BOEM then developed an Area ID recommendation memorandum. The Area ID is an administrative 

prelease step that describes the geographic area for environmental analysis and consideration for 

leasing. On November 20, 2015, the Area ID decision was made. One Area ID was prepared for all 

proposed lease sales. The Area ID memorandum recommended keeping the entire regionwide area 

of the GOM included in the Draft Proposed Program for consideration in this Multisale EIS. The area 

identified for lease includes all of the available unleased blocks in the GOM not subject to 

Congressional moratorium pursuant to the Gulf of Mexico Energy Security Act of 2006.

ALTERNATIVES

BOEM has identified four action alternatives, and the no action, to be analyzed in this 

Multisale EIS. These alternatives are briefly described below. The mitigating measures (pre- and 

postlease), including the proposed stipulations, are fully described in Chapter 2 and Appendix D, 

as are the deferred alternatives not analyzed in detail.

Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Alternative A would allow for a proposed regionwide lease sale encompassing all three 

planning areas within the U.S. portion of the Gulf of Mexico OCS for any given lease sale in the FiveYear Program. This is BOEM’s preferred alternative. This alternative would offer for lease all 

available unleased blocks within the WPA, CPA, and EPA portions of the proposed lease sale area 

for oil and gas operations (Figure 2), with the following exceptions:
x Gulf of Mexico Multisale EIS

(1) whole and portions of blocks deferred by the Gulf of Mexico Energy Security Act 

of 2006 (discussed in the OCS Regulatory Framework white paper [Cameron 

and Matthews, 2016]);

(2) blocks that are adjacent to or beyond the United States’ Exclusive Economic 

Zone in the area known as the northern portion of the Eastern Gap; and

(3) 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 

Multisale EIS).

Figure 2. Proposed Regionwide Lease Sale Area, Encompassing the Available Unleased Blocks within 

All Three Planning Areas (approximately 92.2 million acres with approximately 72.5 million

acres available for lease as of March 2016).

Alternative B—Regionwide OCS Lease Sale Excluding Available Unleased Blocks in the WPA 

Portion of the Proposed Lease Sale Area

Alternative B would allow for a proposed lease sale encompassing the CPA and EPA within 

the U.S. portion of the Gulf of Mexico OCS (Figure 3). Available blocks within the WPA would not

be considered under this alternative. This alternative would offer for lease all available unleased 

blocks within the CPA and EPA portions of the proposed lease sale area as those planning area 

portions described in Alternative A for oil and gas operations, with the following exceptions:
Executive Summary xi

(1) whole and portions of blocks deferred by the Gulf of Mexico Energy Security Act 

of 2006 (discussed in the OCS Regulatory Framework white paper [Cameron 

and Matthews, 2016]); and

(2) blocks that are adjacent to or beyond the United States’ Exclusive Economic 

Zone in the area known as the northern portion of the Eastern Gap.

Figure 3. Proposed Lease Sale Area for Alternative B, Excluding the Available Unleased Blocks in the 

WPA (approximately 66.45 million ac with approximately 48.3 million ac available for lease as 

of March 2016).

Alternative C—Regionwide OCS Lease Sale Excluding Available Unleased Blocks in the 

CPA/EPA Portions of the Proposed Lease Sale Area

Alternative C would allow for a proposed lease sale encompassing the WPA within the U.S. 

portion of the Gulf of Mexico OCS (Figure 4). Available blocks within the CPA and EPA would not

be considered under this alternative. This alternative would offer for lease all available unleased 

blocks within the WPA portion of the proposed lease sale area for oil and gas operations, with the 

following exception:
xii Gulf of Mexico Multisale 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 

Multisale EIS).

Figure 4. Proposed Lease Sale Area for Alternative C, Excluding the Available Unleased Blocks in the 

CPA and EPA (approximately 28.58 million ac with approximately 23.6 million ac available for 

lease as of March 2016).

Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased Blocks 

Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or Blocks South of 

Baldwin County, Alabama, Stipulations

Alternative D could be combined with any of the action alternatives above (A, B, or C) and 

would allow the flexibility to offer leases under any alternative with additional exclusions. Under 

Alternative D, the decisionmaker could exclude from leasing any available unleased blocks subject 

to any one and/or combination of the following stipulations:

• Topographic Features Stipulation;

• Live Bottom (Pinnacle Trend) Stipulation; and

• Blocks South of Baldwin County, Alabama, Stipulation (not applicable to 

Alternative C).
Executive Summary xiii

This alternative considered blocks subject to these stipulations because these areas have 

been emphasized in scoping, can be geographically defined, and adequate information exists 

regarding their ecological importance and sensitivity to OCS oil- and gas-related activities, as shown 

in Figure 5. All of the assumptions (including the other potential mitigating measures) and estimates 

would remain the same as described for any given alternative.

Figure 5. Identified Topographic Features, Pinnacle Trend, and Baldwin County Stipulation Blocks in 

the Gulf of Mexico.

Alternative E—No Action

Alternative E is the cancellation of a single proposed lease sale. The opportunity for 

development of the estimated oil and gas that could have resulted from a proposed action (i.e., a 

single lease sale) or alternative to a proposed action, as described above, would be precluded or 

postponed to a future lease sale. Any potential environmental impacts resulting from a proposed 

lease sale would not occur or would be postponed. Cancellation of a proposed lease sale, however, 

would not stop all OCS oil- and gas-related activities. Activities related to previously issued leases 

and permits (as well as those that may be issued in the future under a separate decision) related to 

the OCS oil and gas program would continue. If a 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 
xiv Gulf of Mexico Multisale EIS

overall level of OCS oil- and gas-related activity would only be reduced by a small percentage, if 

any.

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. Mitigating measures in 

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

the lease. The 10 lease stipulations being considered are the Topographic Features Stipulation; 

Live Bottom (Pinnacle Trend) Stipulation; Military Areas Stipulation; Evacuation Stipulation; 

Coordination Stipulation; Blocks South of Baldwin County, Alabama, Stipulation; Protected Species 

Stipulation; United Nations Convention on the Law of the Sea Royalty Payment Stipulation; Below 

Seabed Operations 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 (Transboundary Stipulation). The United Nations Convention on the Law of the Sea 

Royalty Payment Stipulation is applicable to a proposed lease sale even though it is not an 

environmental or military stipulation. Chapter 2.2.4provides a brief description of each stipulation 

and the potential benefits associated with its use. Appendix D provides a more detailed analysis of 

the 10 lease stipulations and their effectiveness.

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

for Land and Minerals Management (ASLM). The inclusion of the stipulations as part of the analysis 

of the proposed actions 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. In addition, mitigations may be added to plan 

and/or permits for OCS oil- and gas-related activities (Chapter 2.2.4.3). For more information on 

mitigating measures that are added at the postlease stage, refer to Appendix B (“Commonly 

Applied Mitigating Measures”).

DIRECT AND INDIRECT ACTIONS ASSOCIATED WITH A PROPOSED LEASE SALE

BOEM describes the potentially occurring actions associated with a single lease sale and the 

cumulative activities that provide a framework for a detailed analysis of the potential environmental 

impacts. Exploration and development scenarios describe the infrastructure and activities that could 

potentially affect the biological, physical, and socioeconomic resources in the GOM. They also 

include a set of ranges for resource estimates, projected exploration and development activities, and 

impact-producing factors.

Offshore activities are described in the context of scenarios for a 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 a 
Executive Summary xv

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

unleased hydrocarbon resources estimated to be leased and discovered as a result of a 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.

Within each resource section in Chapter 4, the cumulative analysis considers environmental 

and socioeconomic impacts that may result from the incremental impact of a 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). 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, 

impacts from natural occurrences, such as hurricanes, are analyzed.

ENVIRONMENTAL IMPACTS

The affected environment and the potential impacts of a single lease sale and each 

alternative have been described and analyzed by resource. Analysis of the alternatives include 

routine activities, accidental events, cumulative impact analysis, incomplete or unavailable 

information, and conclusions for each resource. This Multisale EIS also considers baseline data in 

the assessment of impacts from a proposed action on the resources and the environment 

(Chapter 4). 

The major issues that frame the environmental analyses in this Multisale EIS 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, wastewater discharges and water quality 

degradation, marine trash and debris, structure and pipeline emplacement activities, platform 

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

fluctuations, land-use planning, impacts to recreation and beaches, aesthetic interference, 

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

resources and activities identified during the scoping process that warrant an environmental analysis 

include air quality, water quality, coastal habitats (including wetlands and seagrasses), barrier 

beaches and associated dunes, live bottom habitats (including topographic features and pinnacle 

trends), Sargassum and associated communities, deepwater benthic communities, marine 

mammals, sea turtles, birds, fishes and invertebrate resources, commercial fisheries, recreational 

fishing, recreational resources, archaeological resources, and socioeconomic factors (including 

environmental justice), and within the CPA only, beach mice.

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 several years, the Gulf Coast 

States and Gulf of Mexico oil and gas activities have been impacted by major hurricanes. The 
xvi Gulf of Mexico Multisale EIS

description of the affected environment includes impacts from these relevant issues on the physical 

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

infrastructure.

Impact Conclusions

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

associated with a proposed action and a proposed action’s incremental contribution to the 

cumulative impacts are described in the individual resource discussions in Chapter 4. A summary 

of the potential impacts from a proposed action on each environmental and socioeconomic resource 

and the conclusions of the analyses can be found in the following discussions. Table 1 provides a 

comparison of the expected impact levels by alternative and is derived from the analysis of each 

resource in Chapter 4. The impact level ratings have been specifically tailored and defined for each 

resource within the Chapter 4 impact analysis. BOEM has concluded that the selection of 

Alternative E would result in no additional discernible impacts to the resources analyzed; therefore, 

Alternative E ratings were not included. Cumulative impacts of current and past activities, however, 

would continue to occur under Alternative E.

Table 1. Alternative Comparison Matrix.

Impact Level Key

Beneficial Negligible Minor Moderate Major

Resource Alternative A Alternative B Alternative C Alternative D

Air Quality Minor Minor Minor Minor

Water Quality Minor Minor Minor Minor

Estuarine Systems Minor Negligible Negligible Negligible to

Minor

Coastal Barrier Beaches 

and Associated Dunes Negligible Negligible Negligible Negligible

Deepwater Benthic 

Communities

Negligible to Negligible to Negligible to Negligible to 

Minor Minor Minor Minor

Sargassum and Associated 

Communities Negligible Negligible Negligible Negligible

Live Bottoms

Topographic Features

Negligible to Negligible to Negligible to Negligible Minor Minor Minor

Pinnacles and Low-Relief 

Features

Negligible to Negligible to Negligible to Negligible Minor Minor Minor

Fishes and Invertebrate 

Resources

Negligible to Negligible to Negligible to Negligible to 

Moderate Moderate Moderate Moderate

Birds Moderate Moderate Moderate Moderate

Protected Species

Marine Mammals

Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate

Sea Turtles Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate
Executive Summary xvii

Impact Level Key

Beneficial Negligible Minor Moderate Major

Resource Alternative A Alternative B Alternative C Alternative D

Beach Mice Negligible Negligible Negligible Negligible

Protected Birds Negligible to Negligible to Negligible to Negligible to 

Moderate Moderate Moderate Moderate

Protected Corals Negligible to Negligible to Negligible to Negligible to

Minor Minor Minor Minor

Commercial Fisheries Beneficial to Beneficial to Beneficial to Beneficial to 

Minor Minor Minor Minor

Recreational Fishing Negligible to Negligible to Negligible to Negligible to 

Minor Minor Minor Minor

Recreational Resources Beneficial to Beneficial to Beneficial to Beneficial to 

Minor Minor Minor Minor

Archaeological Resources Negligible Negligible Negligible Negligible

Human Resources and Land 

Use

Land Use and Coastal 

Infrastructure

Negligible to Negligible to Negligible to Negligible to

Major Major Major Major

Economic Factors Negligible to Negligible to Negligible to Negligible to 

Minor Minor Minor Minor

Social Factors (including 

Environmental Justice) Minor Minor Minor Minor

Note: BOEM has concluded that the selection of Alternative E would result in no additional discernible 

impacts to the resources analyzed; however, cumulative impacts of current and past activities would 

continue to occur.

Air Quality

Air quality is the degree at which the ambient air is free of pollution; it is assessed by 

measuring the pollutants in the air. To protect public health and welfare, the Clean Air Act 

established National Ambient Air Quality Standards (NAAQS) for certain common and widespread 

pollutants. The seven common "criteria pollutants" are particle pollution (also known as particulate 

matter [PM2.5 and PM10]), carbon monoxide (CO); nitrogen dioxide (NO2); sulfur dioxide (SO2); lead 

(Pb); and ozone (O3). Air emissions from OCS oil and gas development in the Gulf of Mexico would 

arise from emission sources related to drilling and production with associated vessel support, flaring 

and venting, decommissioning, fugitive emissions, and oil spills. Associated activities that take place 

as a result of a proposed action support and maintain the OCS oil and gas platform sources. Air 

emissions from non-OCS oil- and gas-related emissions in the Gulf of Mexico would arise from 

emission sources related to State oil and gas programs, onshore industrial and transportation 

sources, and natural events. Since the primary NAAQS are designed to protect human health, 

BOEM focuses on the impact of these activities on the States, where there are permanent human 

populations.
xviii Gulf of Mexico Multisale EIS

Based on Year 2008 and Year 2011 OCS emission inventories, postlease 1-hour NOx

modeling, and past studies, emissions of pollutants into the atmosphere from routine activities and 

accidental events associated with the OCS Program are projected to be minor. Additionally, 

reductions in emissions have been achieved through the use of low sulfur fuels, catalytic reduction, 

and other efforts. The incremental contribution of a single regionwide proposed lease sale to the 

cumulative impacts would be minor. Portions of the Gulf Coast onshore areas have ozone levels 

that exceed the Federal air quality standard, but the incremental contribution from a regionwide 

proposed lease sale would be very small. The cumulative contribution to visibility impairment from a 

regionwide proposed lease sale is also expected to be very small. A full analysis of air quality can 

be found in Chapter 4.1. 

Water Quality

Water quality is a term used to describe the condition or environmental health of a waterbody 

or resource, reflecting its particular biological, chemical, and physical characteristics and the ability 

of the waterbody to maintain the ecosystems it supports and influences. It is an important measure 

for both ecological and human health. The impacts of OCS Program-related routine operational 

discharges (Chapter 3.1.5.1) on water quality are short term and localized, and are therefore 

considered negligible. The potential impacts from OCS Program-related oil spills on water quality 

after mitigation are also short term and are considered minor. This is because, after removal of 

most free product, the residual oil dissipates quickly through dispersion and weathering; however, 

secondary impacts to water quality may occur, such as the introduction of additional hydrocarbon 

into the dissolved phase through the use of dispersants and the sinking of hydrocarbon residuals 

from burning. The impacts from a proposed action are a small addition to the cumulative impacts on 

water quality when compared with inputs from hypoxia, potentially leaking shipwrecks, chemical 

weapon and industrial waste dumpsites, natural oil seeps, and natural turbidity. The incremental 

contribution of the routine activities and accidental events associated with a proposed action to the 

cumulative impacts on water quality is not expected to be significant. A full analysis of water quality 

can be found in Chapter 4.2. 

Coastal Habitats

Estuarine Systems (Wetlands and Seagrasses/Submerged Vegetation)

The estuarine system is the transition zone between freshwater and marine environments. It 

can consist of many habitats, including wetlands and submerged vegetation. The impacts to these 

habitats from routine activities associated with a proposed action are expected to be negligible due 

to the projected low probability for any new pipeline landfalls (0-1 projected), the minimal contribution 

to the need for maintenance dredging, and the mitigating measures expected to be used to further 

reduce these impacts, e.g., use of modern techniques such as directional drilling. Overall, impacts 

to estuarine habitats from oil spills associated with activities related to a proposed action would be 

expected to be minor because of the distance of most postlease activities from the coast, the 

expected weathering of spilled oil, the projected low probability of large spills near the coast, the 

resiliency of wetland vegetation, and the available cleanup techniques. Cumulative impacts to 
Executive Summary xix

estuarine habitats are caused by a variety of factors, including the OCS oil- and gas-related and 

non-OCS oil- and gas-related activities outlined in Chapter 4.3.1 and the human and natural 

impacts. Development pressures in the coastal regions of the GOM have been largely the result of 

tourism and residential beach-side development, and this trend is expected to continue. Storms will 

continue to impact the coastal habitats and have differing impacts. The incremental contribution of a 

proposed action to the cumulative impacts on estuarine habitats is expected to be negligible to 

minor. A full analysis of estuarine habitats can be found in Chapter 4.3.1. 

Coastal Barrier Beaches and Associated Dunes

The coastal barrier beaches and associated dunes are those beaches and dunes that line 

the coast of the northern GOM, including both barrier islands and beaches on the mainland. The 

impacts to coastal barrier beaches and dunes from routine activities associated with a proposed 

action are expected to be negligible due to the minimal number of projected onshore pipelines, the 

minimal contribution to vessel traffic and the need for maintenance dredging, and the mitigating 

measures that would be used to further reduce these impacts. The greater threat from an oil spill to 

coastal beaches is from a coastal spill as a result of a nearshore vessel accident or pipeline rupture 

and from cleanup activities. Overall, impacts to coastal barrier beaches and dunes from oil spills 

associated with OCS oil- and gas-related activities related to a proposed action would be expected 

to be minor because of the distance of most of the resulting activities from the coast, expected 

weathering of spilled oil, projected low probability of large spills near the coast, and available 

cleanup techniques. Cumulative impacts to coastal barrier beaches and dunes are caused by a 

variety of factors, including the OCS oil- and gas-related and non-OCS oil- and gas-related activities 

outlined in Chapter 4.3.2 and the other human and natural impacts. Development pressures in the 

coastal regions of the GOM have been largely the result of tourism and residential beach-side 

development, and this trend is expected to continue. Efforts to stabilize the GOM shoreline have 

adversely impacted coastal beach landscapes. Storms will continue to impact the coastal habitats 

and have differing impacts. The incremental contribution of a proposed action to the cumulative 

impacts on estuarine habitats is expected to be negligible to minor. A full analysis of coastal 

barrier beaches and associated dunes can be found in Chapter 4.3.2. 

Deepwater Benthic Communities

BOEM defines “deepwater benthic communities” as including both chemosynthetic 

communities (chemosynthetic organisms plus seep-associated fauna) and deepwater coral 

communities (deepwater coral plus associated fauna). These communities are typically found in 

water depths of 984 feet (ft) (300 meters [m]) or deeper throughout the GOM, although deepwater 

benthic habitats are relatively rare compared with ubiquitous soft bottoms. The OCS oil- and gasrelated impact-producing factors for deepwater benthic communities can be grouped into three main 

categories: (1) bottom-disturbing activities; (2) drilling-related sediment and waste discharges; and 

(3) noncatastrophic oil spills. These impact-producing factors have the potential to damage 

individual deepwater habitats and disrupt associated benthic communities if insufficiently distanced 

or otherwise mitigated. However, impacts from individual routine activities and accidental events are 

usually temporary, highly localized, and expected to impact only small numbers of organisms and 
xx Gulf of Mexico Multisale EIS

substrates at a time. Moreover, use of the expected site-specific plan reviews/mitigations will 

distance activities from deepwater benthic communities, greatly diminishing the potential effects. 

Therefore, at the regional, population-level scope of this analysis and assuming adherence to all 

expected regulations and mitigations, impacts from routine activities and reasonably foreseeable 

accidental events are expected to be negligible to minor. Proposed OCS oil- and gas-related 

activities would also contribute incrementally to the overall OCS and non-OCS cumulative effects 

experienced by live bottom habitats. The OCS oil- and gas-related cumulative impacts to deepwater 

benthic communities are estimated to be negligible to minor. A full analysis of deepwater benthic 

communities can be found in Chapter 4.4. 

Sargassum and Associated Communities

Sargassum in the GOM is comprised of S. natans and S. fluitans, and is characterized by a 

brushy, highly branched thallus with numerous leaf-like blades and berrylike pneumatocysts. The 

Sargassum cycle is truly expansive, encompassing most of the western Atlantic Ocean and the Gulf 

of Mexico with the growth, death, and decay of these plant and epiphytic communities, which may 

play a substantial role in the global carbon cycle. Several impacting factors can affect Sargassum, 

including vessel-related operations, oil and gas drilling discharges, operational discharges, 

accidental spills, non-OCS oil- and gas-related vessel activity, and coastal water quality. Routine 

vessel operations and accidental events that occur during drilling operations or vessel operations, 

and oiling due to an oil spill were the impact-producing factors that could be reasonably expected to 

impact Sargassum populations in the GOM. All of these impact-producing factors would result in the 

death or injury to the Sargassum plants or to the organisms that live within or around the plant 

matrix. However, the unique and transient characteristics of the life history of Sargassum and the 

globally widespread nature of the plants and animals that use the plant matrix buffer against impacts 

at any given location. Impacts to the overall population of the Sargassum community are therefore 

expected to be negligible from either routine activities or reasonably foreseeable accidental events. 

The incremental impact of OCS oil- and gas-related activities on the population of Sargassum would 

be negligible and would not result in cumulative impacts to the population. Impacts from changing 

water quality would be much more influential on Sargassum than OCS development and would still 

occur without the presence of OCS oil- and gas-related activities. A full analysis of Sargassum and 

associated communities can be found in Chapter 4.5. 

Live Bottom Habitats

Topographic Features

Defined topographic features (Chapter 4.6.1) are a subset of GOM live bottom habitats that 

are large enough to have an especially important ecological role, with specific protections defined in 

the proposed Topographic Features Stipulation. Within the Gulf of Mexico, BOEM has identified 

37 topographic features where some degree of protection from oil and gas development may be 

warranted based on geography and ecology. Of all the possible impact-producing factors, it was 

determined that bottom-disturbing activities associated with drilling, exploration, and vessel 

operations were the only impact-producing factors from routine activities that could be reasonably 
Executive Summary xxi

expected to substantially impact topographic features. The impact-producing factors resulting from 

accidental events include bottom-disturbing activities from drilling, exploration, and vessel 

operations, as well as the release of sediments and toxins released during drilling. Oil spill-related 

activities were also considered to be a substantial source of potential impact to topographic features.

Adherence to the Topographic Features Stipulation, which is detailed in Appendix D, would 

assist in preventing most of the potential impacts on topographic feature communities by increasing 

the distance of OCS oil- and gas-related activities from these features. Should this stipulation be 

applied to any future lease sale, as it has been historically, impacts of a proposed action to 

topographic features from routine activities and accidental events or the cumulative impact of a 

proposed action in the GOM are expected to be negligible. The incremental contribution of a 

proposed action to the cumulative impacts on topographic features is expected to be negligible with 

adherence to the proposed Topographic Features Stipulation. Impacts ranging from negligible to 

moderate may still be expected from non-OCS oil- and gas-related activities depending on factors 

such as fishing and pollution; however, the incremental impact of the proposed activities should not 

result in an augmentation of the expected impacts. Additionally, any localized impacts at one 

topographic feature does not preclude that impacts will occur at other topographic features. A full 

analysis of topographic features can be found in Chapter 4.6.1. 

Pinnacles and Low-Relief Features

The Pinnacle Trend is an approximately 64 x 16 mile (103 x 26 kilometer) area in water 

depths of about 200-650 ft (60-200 m). It is in the northeastern portion of the CPA at the outer edge 

of the Mississippi-Alabama shelf between the Mississippi River and De Soto Canyon (Figure 2-4-to

Figure 4-16). Outside of the Pinnacle Trend, low-relief live bottom epibenthic communities occur in 

isolated locations in shallow waters (<984 ft; 300 m) throughout the GOM, wherever there is suitable

hard substrate and other physical conditions (e.g., depth, turbidity, etc.) for development. Hard 

bottom habitats occur throughout the GOM but are relatively rare compared with ubiquitous soft 

bottoms. The impact-producing factors for pinnacles and low-relief live bottom features can be 

grouped into three main categories: (1) bottom-disturbing activities; (2) drilling-related sediment and 

waste discharges; and (3) oil spills. These impact-producing factors have the potential to damage 

individual deepwater habitats and disrupt associated benthic communities if insufficiently distanced 

or otherwise mitigated. At the broad geographic and temporal scope of this analysis, and assuming 

adherence to all expected lease stipulations and typically applied regulations and mitigations, routine 

activities are expected to have largely short-term localized and temporary effects. Although 

accidental events have the potential to cause severe damage to specific live bottom communities, 

the number of such events is expected to be very small. Therefore, at the regional, population-level 

scope of this analysis, impacts from reasonably foreseeable routine activities and accidental 

activities are expected to be negligible to minor. Proposed OCS oil- and gas-related activities 

would also contribute incrementally to the overall OCS and non-OCS cumulative impacts 

experienced by live bottom habitats. The OCS oil- and gas-related cumulative impacts to live bottom 

communities are estimated to be negligible. A full analysis of pinnacles and low-relief features can 

be found in Chapter 4.6.2. 
xxii Gulf of Mexico Multisale EIS

Fish and Invertebrate Resources

The distribution of fishes and invertebrates vary widely, and species may be associated with 

different habitats at various life stages, which is discussed further in Chapter 4.7. The impactproducing factors affecting these resources are anthropogenic sound, bottom-disturbing activities, 

habitat modification, and accidental oil spills. The impacts from routine activities, excluding 

infrastructure emplacement, would be expected to be negligible or minor due to short-term 

localized effects. The installation of OCS oil- and gas-related infrastructure constitutes a long-term 

modification of the local habitat and is hypothesized to have resulted over the life of the program in 

moderate changes in the distribution of some species. Although this effect is not necessarily 

adverse and infrastructure is expected to be decommissioned and sites restored to natural habitat, 

the cumulative impact over the life of the OCS Program extensively pertains to time and space. 

Accidental spills have been historically low-probability events and are typically small in size. The 

expected impact to fishes and invertebrate resources from accidental oil spills is negligible. 

Commercial and recreational fishing are expected to have the greatest direct effect on fishes and 

invertebrate resources, resulting in impact levels ranging from negligible for most species to 

potentially moderate for some targeted species (e.g., hogfish spp., gray triggerfish, and greater 

amber jack [Seriola dumerili]). The analysis of OCS oil- and gas-related and non-OCS oil- and gasrelated routine activities, accidental events, and cumulative impacts indicates the overall impact to 

fishes and invertebrate resources would range from negligible to moderate for different species. A 

full analysis of fish and invertebrate resources can be found in Chapter 4.7. 

Birds

The affected birds include both terrestrial songbirds and many groups of waterbirds. Routine 

impacts to coastal, marine, and migratory birds that were considered include routine discharges and 

wastes, noise, platform severance with explosives (barotrauma), geophysical surveys with airguns, 

platform presence and lighting, construction of OCS oil- and gas-related onshore facilities, and 

pipeline landfalls. The impacts to birds from OCS oil-and gas-related routine activities are similar 

wherever they may occur in the GOM, and all are considered negligible to minor. Negligible 

impacts would be little to no impacts that are measured or measurable for a population. No mortality 

of a flock or large population would occur, and no overall disturbance-causing changes in behavioral 

patterns would be expected. Minor impacts would occur when one of the two following conditions 

are met: (1) flocks or large populations of birds would experience stimuli or impact-producing factors 

and would be disturbed or otherwise affected overall, resulting in acute behavioral changes; 

however, these impacts would be short term and reversible; and (2) one or more incidents where 

one or more individuals experience injury or mortality may occur, but with no measured or 

measurable impact on a large population. Accidental impacts to birds are caused by oil spills, spill 

cleanup, and emergency air emissions. Seabirds may not always experience the greatest impacts 

from a spill but it may take longer for populations to recover because of their unique population 

ecology (demography). Some species of seabirds can have a clutch size of just one egg, and they 

have relatively long life spans and often have delayed age at first breeding. Impacts for overall

accidental events would be moderate. However, other seabirds, such as gulls, have larger clutches 

(laughing gulls usually have three eggs/clutch except in the tropics) and may recover quite quickly. 
Executive Summary xxiii

This conclusion is based on the increment of a proposed action compared with all cumulative OCS 

oil- and gas-related and non-OCS oil- and gas-related impacts. A full analysis of birds can be found 

in Chapter 4.8. 

Protected Species

Marine Mammals

The Gulf of Mexico marine mammal community is diverse and distributed throughout the 

GOM, with the greatest abundances and diversity of species inhabiting oceanic and OCS waters. 

The major potential impact-producing factors affecting marine mammals in the GOM as a result of 

cumulative past, present, and reasonably foreseeable OCS energy-related activities are 

decommissioning activities, operational discharges, G&G activities, noise, transportation, marine 

debris, and accidental oil spill and spill-response activities. Accidental events that involve large 

spills, particularly those continuing to flow fresh hydrocarbons into oceanic and/or outer shelf waters 

for extended periods (i.e., days, weeks, or months), pose an increased likelihood of impacting 

marine mammal populations inhabiting GOM waters. While accidental events have the potential to 

impact marine mammal species, the number of such events is expected to be very small.

At the regional, population-level scope of this analysis, impacts from routine activities and 

reasonably foreseeable accidental activities are expected to be negligible to moderate. Proposed 

OCS oil- and gas-related activities would also contribute incrementally to the overall OCS and nonOCS cumulative effects experienced by marine mammal populations. The incremental contribution 

of a proposed action to cumulative impacts to marine mammal populations, depending upon the 

affected species and their respective population estimate, even when taking into consideration the 

potential impacts of the Deepwater Horizon explosion, oil spill, and response; non-OCS oil- or gasrelated factors; and the minimization of the OCS oil- or gas-related impacts through lease 

stipulations and regulations, would be expected to be negligible. A full analysis of marine mammals 

can be found in Chapter 4.9.1. 

Sea Turtles

Five sea turtle species have been listed and are present throughout the northern GOM; 

however, only Kemp’s ridley and loggerheads commonly nest on beaches in the GOM. Because of 

expected mitigations (e.g., BOEM and the Bureau of Safety and Environmental Enforcement [BSEE] 

proposed compliance with Notices to Lessees and Operators [NTLs] under the proposed Protected 

Species Stipulation and conditions of approval on postlease activities), the routine activities (e.g., 

noise or transportation) and accidental events (e.g., oil spills) related to a proposed action are not 

expected to have long-term adverse effects on the size and productivity of any sea turtle species or 

populations in the northern GOM. Lethal effects could occur from chance collisions with OCS oiland gas-related service vessels or ingestion of accidentally released plastic materials from OCS oiland gas-related vessels and facilities. However, there have been no reports to date on such 

incidences. Most routine activities and accidental events are therefore expected to have negligible

to moderate impacts. For example, a minor impact might be a behavioral change in response to 
xxiv Gulf of Mexico Multisale EIS

noise while a moderate impact might be a spill contacting an individual and causing injury or 

mortality.

Historically, intense harvesting of eggs, loss of suitable nesting beaches, and fishery-related 

mortality have led to the rapid decline of sea turtle populations. Anthropogenic actions continue to 

pose the greatest threat to sea turtles since their listing under the Endangered Species Act (ESA), 

as well as different natural threats including climate change and natural disasters. Cumulative 

impacts to sea turtles would be expected to be negligible as a result of a proposed action. 

Population-level impacts are not anticipated. A full analysis of sea turtles can be found in Chapter 

4.9.2. 

Beach Mice

The four subspecies of beach mouse (Peromyscus polionotus ssp.) are small coastal 

rodents that are only found along beaches in parts of Alabama and northwest Florida. Beach mice 

rely on dune systems as favorable habitat for foraging and maintaining burrows. Due to the distance 

between beach mouse habitat and OCS oil- and gas-related activities, routine impacts are not likely 

to affect beach mouse habitat except under very limited situations. Pipeline emplacement or 

construction, for example, could cause temporary degradation of beach mouse habitat; however, 

these activities are not expected to occur in areas of designated critical habitat. Accidental oil spills 

and associated spill-response efforts are not likely to impact beach mice or their critical habitat 

because the species live above the intertidal zone where contact is less likely. Habitat loss from 

non-OCS oil- and gas-related activities (e.g., beachfront development) and predation have the 

greatest impacts to beach mice. The overall analyses of impact-producing factors associated with 

the routine activities, accidental events, and cumulative impacts of OCS oil- and gas-related and 

non-OCS oil- and gas-related activities on beach mice concluded that impacts from a proposed 

action would be negligible. A full analysis of beach mice can be found in Chapter 4.9.3. 

Protected Birds

Protected birds are those species or subspecies listed under the ESA by the U.S. Fish and

Wildlife Service (FWS) as threatened or endangered due to the decrease in their population sizes or 

loss of habitat; therefore, a proposed action could have a greater impact. BOEM is undergoing 

consultation with the FWS to minimize the potential impacts to ESA-listed species. Impacts from 

routine activities, which include discharges and wastes affecting air and water quality, noise, and 

possibly artificial lighting, would be negligible to protected birds. The listed bird species considered 

are typically coastal birds and would not be exposed to much of the oil- and gas-related activities. 

Waste discharges to air or water produced as a result of routine activities are regulated by the U.S. 

Environmental Protection Agency and BOEM, and these discharges are subject to limits to reduce 

potential impacts; therefore, due to precautionary requirements and monitoring, the impacts to 

protected birds would be negligible. The major impact-producing factors resulting from accidental 

events associated with a proposed action that may affect protected birds include accidental oil spills 

and response efforts and marine debris. In the case of an accidental oil spill, impacts would be 

negligible to moderate depending on the magnitude and time and place of such an event. Major 
Executive Summary xxv

impacts could occur if a large oil spill occurred with direct contact to a protected bird species or if the 

habitat became contaminated resulting in mortality of a listed species. Marine debris produced by 

OCS oil- and gas-related activities as a result of accidental disposal into the water may affect 

protected birds by entanglement or ingestion. Due to the regulations prohibiting the intentional 

disposal of items, impacts would be expected to be negligible; however, impacts may scale up to 

moderate if the accidental release of marine debris caused mortality of a listed bird. Overall, BOEM 

would expect negligible to moderate impacts to protected birds considering routine activities, 

accidental events, and cumulative impacts. A full analysis of protected birds can be found in 

Chapter 4.9.4. 

Protected Corals

Elkhorn, staghorn, boulder star, lobed star, and mountainous corals are listed by the National 

Marine Fisheries Service as threatened due to the decrease in their population sizes; therefore, 

impacts from a proposed action could have a higher level than realized by other coral species. 

BOEM understands this and is undergoing consultation for these species to minimize the potential 

impacts. Though the listed species are protected, they would have the same impacts from a 

proposed action as other coral species. Without effective mitigations, a proposed action could 

directly impact coral habitat within the GOM. Assuming adherence to all expected lease stipulations 

and other postlease, protective restrictions and mitigations, the routine activities related to a 

proposed action are expected to have mostly short-term localized and temporary effects because 

the site-specific survey information and distancing requirements described in NTL 2009-G39 will 

allow BOEM to identify and protect live bottom features (which protected corals may inhabit) from 

harm by proposed OCS oil- and gas-related activities during postlease reviews. While accidental 

events have the potential to cause severe damage to specific coral communities, the number of such 

events is expected to be small. Further, many of the protected corals occur in the Flower Garden 

Banks National Marine Sanctuary, which under the current boundaries is not proposed for future 

leasing under any of the alternatives in this Multisale EIS. Therefore, the incremental contribution of 

activities resulting from a proposed action to the overall cumulative impacts on protected corals is 

expected to be negligible. Proposed OCS oil- and gas-related activities would contribute 

incrementally to the overall OCS and non-OCS cumulative impacts experienced by corals. A full 

analysis of protected corals can be found in Chapter 4.9.5. 

Commercial Fisheries

A proposed action could affect commercial fisheries by affecting fish populations or by 

affecting the socioeconomic aspects of commercial fishing. The impacts of a proposed action on 

fish populations are presented in Chapter 4.7. Routine activities such as seismic surveys, drilling 

activities, and service-vessel traffic can cause space-use conflicts with fishermen. Structure 

emplacement could have positive or negative impacts depending on the location and species. For 

example, structure emplacement prevents trawling in the associated area and, thus, could impact 

the shrimp fishery. On the other hand, production platforms can facilitate fishing for reef fish such as 

red snapper and groupers. Accidental events, such as oil spills, could cause fishing closures and 

have other impacts on the supply and demand for seafood. However, accidental events that could 
xxvi Gulf of Mexico Multisale EIS

arise from a proposed action would likely be small and localized. A proposed action would be 

relatively small when compared with the overall OCS Program, State oil and gas activities, overall 

vessel traffic, hurricanes, economic factors, Federal and State fisheries management strategies, and 

other non-OCS oil- and gas-related factors. Therefore, the incremental contribution of a proposed 

action to the cumulative impacts to commercial fisheries would range from beneficial to minor. The 

exact impacts would depend on the locations of activities, the species affected, the intensity of 

commercial fishing activity in the affected area, and the substitutability of any lost fishing access. 

Alternative E would prevent these impacts from occurring, although commercial fisheries would still 

be subject to the impacts from the OCS Program, as well as the impacts from non-OCS sources. A 

full analysis of commercial fisheries can be found in Chapter 4.10. 

Recreational Fishing

The Gulf of Mexico’s extensive estuarine habitats (Chapter 4.3.1), live bottom habitats 

(Chapter 4.6), and artificial substrates (including artificial reefs, shipwrecks, and oil and gas 

platforms) support several valuable recreational fisheries. Alternatives A-D can affect recreational 

fishing by affecting fish populations or by affecting the socioeconomic aspects of recreational fishing. 

The impacts of Alternatives A-D on fish populations are presented in Chapter 4.7. Vessel traffic can 

cause space-use conflicts with anglers. Structure emplacement generally enhances recreational 

fishing, although this positive effect will be offset during decommissioning unless a structure were 

maintained as an artificial reef. Accidental events, such as oil spills, can cause fishing closures and 

can affect the aesthetics of fishing in an area. However, accidental events that could arise would 

likely be small and localized. Alternatives A-D should also be viewed in light of overall trends in 

OCS platform decommissioning, State oil and gas activities, overall vessel traffic, hurricanes, 

economic factors, and Federal and State fisheries management strategies. The incremental impacts 

of Alternatives A-D on recreational fisheries are expected to be negligible to minor. A full analysis 

of recreational fishing can be found in Chapter 4.9.11. 

Recreational Resources

Alternatives A-D would contribute to the negligible to minor aesthetic impacts and space-use 

conflicts that arise due to the broader OCS Program. These conflicts arise due to marine debris, the 

visibility of platforms, and vessel traffic. Structure emplacements can have positive impacts on 

recreational fishing and diving because platforms often act as artificial reefs. Oil spills can negatively 

affect beaches and other coastal recreational resources. Alternatives A-D should also be viewed in 

light of economic trends, as well as various non-OCS oil- and gas-related factors that can cause 

space-use conflicts and aesthetic impacts, such as commercial and military activities. Because of 

the relatively small contribution of any given lease sale under any of the proposed action alternatives 

to the overall OCS Program, in addition to other non-OCS oil- and gas-related activities, the various 

impacts are expected to be beneficial to minor. A full analysis of recreational resources can be 

found in Chapter 4.12. 
Executive Summary xxvii

Archaeological Resources

Archaeological resources are any material remains of human life or activities that are at least 

50 years of age and that are capable of providing scientific or humanistic understanding of past 

human behavior, cultural adaptation, and related topics through the application of scientific or 

scholarly techniques, such as controlled observation, contextual measurement, controlled collection, 

analysis, interpretation, and explanation (30 CFR § 250.105). Archaeological resources are 

primarily impacted by any activity that directly disturbs or has the potential to disturb the seafloor. 

For the OCS Program, this includes the placement of drilling rigs and production systems on the 

seafloor; pile driving associated with platform emplacement; pipeline placement and installation; the 

use of seismic receiver nodes and cables; the dredging of new channels, as well as maintenance 

dredging of existing channels; anchoring activities; post-decommissioning activities, including 

trawling clearance; and the masking of archaeological resources from industry-related infrastructure 

and debris.

Regardless of which planning area a proposed lease sale is held, the greatest potential 

impact to an archaeological resource as a result of a proposed action under any of the action 

alternatives is site-specific and would result from direct contact between an offshore activity or 

accidental event and a site. Archaeological surveys, where required prior to an operator beginning 

OCS oil- and gas-related activities on a lease, are expected to be effective at identifying possible 

archaeological sites. There is no acceptable threshold of negative cumulative impacts to 

archaeological sites. A proposed action’s alternatives, including the drilling of wells and installation 

of platforms, installation of pipelines, anchoring, and removal of platforms and other structures 

installed on the seafloor and site clearance activities without archaeological review and mitigation, 

may result in major, adverse impacts to archaeological sites. Identification, evaluation, and 

avoidance or mitigation of archeological resources is expected to result in negligible, long-term 

cumulative impacts to archeological resources; however, if an archaeological site were to be 

impacted, impacts may range from negligible to major. A full analysis of archaeological resources 

can be found in Chapter 4.13. 

Human Resources and Land Use (Including Environmental Justice)

Land Use and Coastal Infrastructure

Oil and gas exploration, production, and development activities on the OCS are supported by 

an expansive onshore network of coastal infrastructure that includes hundreds of large and small 

companies. Because OCS oil- and gas-related activities are supported by this long-lived, expansive 

onshore network, the potential impacts of a proposed lease sale are not expected to produce any 

major impacts to land use and coastal infrastructure. The impacts of reasonably foreseeable 

accidental events such as oil spills, chemical and drilling fluid spills, and vessel collisions are not 

likely to last long enough to adversely affect overall land use or coastal infrastructure in the analysis 

area. In the cumulative analysis, activities relating to all past, present, and future OCS oil- and 

gas-related activities and State oil and gas production are expected to minimally affect the current 

land use of the analysis area because most subareas have strong industrial bases and designated 
xxviii Gulf of Mexico Multisale EIS

industrial parks. Non-OCS oil- and gas-related factors contribute substantially to the cumulative 

impacts on land use and coastal infrastructure, while there is only a small incremental contribution of 

a proposed lease sale. The cumulative impacts on land use and coastal infrastructure could range 

from negligible to major depending on the specifics of each situation, whether the impacts are 

measurable, how long the impacts would last, and the size of the affected geographic area as 

defined in Chapter 4.14.1. A full analysis of land use and coastal infrastructure can be found in 

Chapter 4.14.1. 

Economic Factors

A proposed lease sale would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Some of these impacts would 

be concentrated along the Gulf Coast, while others would be widely distributed. A proposed lease 

sale would also lead to negative economic impacts arising from accidental events and other sources. 

There would be some differences in economic impacts among Alternatives A-D, corresponding to 

the differences in the scales and distributions of likely activities. Alternatives A-D should be viewed 

in light of the OCS Program, as well the numerous forces that can affect energy markets and the 

overall economy. Most of the incremental economic impacts of a proposed action are forecast to be 

positive, although there would be some negligible to minor adverse impacts due to oil spills and to 

the effects on industries that compete with the offshore oil and gas industry for resources. A full 

analysis of economic factors can be found in Chapter 4.14.2. 

Social Factors (Including Environmental Justice)

Potential social impacts resulting from a proposed action would occur within the larger 

socioeconomic context of the GOM region. The affected environment of the analysis area is quite 

large geographically and in terms of population (133 counties and parishes with over 22.7 million 

residents). The impacts from routine activities related to a proposed action are expected to be 

negligible, widely distributed, and to have little impact because of the existing extensive and 

widespread support system for the petroleum industry and its associated labor force. Outside of a 

low-probability catastrophic oil spill, which is not reasonably foreseeable and not part of a proposed 

action, any potential accidental events are not likely to be of sufficient scale or duration to have 

adverse and disproportionate long-term impacts for people and communities in the analysis area. 

Non-OCS oil- and gas-related factors, which include all human activities, natural events, and 

processes, actually contribute more to cumulative impacts than do factors related to OCS oil- and 

gas-related activities alone. When considered with existing and projected routine activities and 

cumulative impacts and the potential accidental events, the incremental contributions of a proposed 

action and the OCS Program to social impacts are expected to be minor. The oil and gas industry 

in the GOM region is expansive and long-lived over several decades with substantial infrastructure in 

place to support both onshore and offshore activities. BOEM’s scenario estimates call for 0-1 new 

gas processing plant and 0-1 new pipeline landfall over the 50-year life of a single proposed action. 

Impacts to GOM populations from a proposed action would be immeasurable for environmental 

justice since these low-income and minority communities are located onshore, distant from Federal 

OCS oil- and gas-related activities. Also, since these vulnerable populations are located within the 
Executive Summary xxix

larger context of onshore and State-regulated nearshore oil and gas activities that are connected to 

downstream infrastructure over which BOEM has no regulatory authority, BOEM has determined 

that a proposed action would not produce environmental justice impacts in the GOM region. A full 

analysis of social factors and an environmental justice determination can be found in Chapter 

4.14.3. 

APPENDICES

To improve the readability of this Multisale EIS, more detailed supporting information has 

been placed in the appendices, which include postlease processes, commonly applied mitigating 

measures, a Memorandum of Agreement between BOEM and the U.S. Environmental Protection 

Agency, prelease stipulations, OSRA figures, species not considered further, and State Coastal 

Management Programs.

Appendix A describes postlease activities, including the following: geological and 

geophysical 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 postlease activities; 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.

Appendix B describes commonly applied mitigations that were developed as a result the 

continuing OCS Program in the Gulf of Mexico. These are mitigations that BOEM and BSEE could 

apply to permits and approvals. These 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-prone areas, and shunting of drill effluents in the 

vicinity of biologically sensitive features. Operational compliance of the mitigating measures is 

enforced through BSEE’s onsite inspection program.

Appendix C is the Memorandum of Agreement between BOEM and the USEPA; it outlines 

the roles and responsibilities for both agencies during the preparation of this Multisale EIS.

Appendix D describes the potential lease stipulations that were developed as a result of 

numerous scoping efforts for the continuing OCS Program in the Gulf of Mexico. The 10 lease 

stipulations being considered are the Topographic Features Stipulation; Live Bottom (Pinnacle 

Trend) Stipulation; Military Areas Stipulation; Evacuation Stipulation; Coordination Stipulation; 

Blocks South of Baldwin County, Alabama, Stipulation; Protected Species Stipulation; United 

Nations Convention on the Law of the Sea Royalty Payment Stipulation; Below Seabed Operations 

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 

(Transboundary Stipulation). The United Nations Convention on the Law of the Sea Royalty 
xxx Gulf of Mexico Multisale EIS

Payment Stipulation is applicable to a proposed lease sale even though it is not an environmental or 

military stipulation.

Appendix E provides the combined probabilities for an offshore oil spill ≥1,000 barrels 

occurring and contacting coastal and offshore areas for each of the proposed actions.

Appendix F is a listing of species not considered further in this Multisale EIS because these 

species are not generally found in the area of activity and/or impact. Therefore, it is not reasonably 

foreseeable that these species would have population effects from a proposed action.

Appendix G describes State Coastal Management Programs (CMPs). Each State’s CMP is 

a comprehensive statement setting forth objectives, enforceable policies or guidelines, and 

standards for public and private use of land and water resources and uses in that State’s coastal 

zone. The programs provide for direct State land and water use planning and regulations. The 

programs also include a definition of what constitutes permissible land uses and water uses. To 

ensure conformance with State CMP policies or guidelines and local land use plans, BOEM 

prepares a Federal consistency determination for each proposed OCS lease sale. Federal 

consistency is the Coastal Zone Management Act requirement where Federal agency activities that 

have reasonably foreseeable effects on any land or water use or natural resource of the coastal 

zone must be consistent to the maximum extent practicable with the enforceable policies or 

guidelines of a coastal State’s federally approved CMP.
Table of Contents xxxi

TABLE OF CONTENTS

Volume I

Page

EXECUTIVE SUMMARY .................................................................................................................... VII

LIST OF FIGURES............................................................................................................................XLV

LIST OF TABLES.............................................................................................................................XLIX

ABBREVIATIONS AND ACRONYMS ..................................................................................................LI

CONVERSION CHART .................................................................................................................... LVII

1 PURPOSE OF AND NEED FOR THE PROPOSED ACTIONS..................................................... 1-3

1.1 Purpose of the Proposed Actions........................................................................................... 1-4

1.2 Need for the Proposed Actions .............................................................................................. 1-5

1.3 OCS Oil and Gas Program Planning and Decision Process ................................................. 1-6

1.3.1 Prelease Process......................................................................................................... 1-7

1.3.1.1 Five-Year Program of Proposed Offshore Lease Sales................................ 1-7

1.3.1.2 Individual Lease Sale Consultation and Decision Process ........................... 1-8

1.3.2 Gulf of Mexico Postlease Activities............................................................................ 1-10

1.4 The Decision to be Made ..................................................................................................... 1-11

1.5 Regulatory Framework ......................................................................................................... 1-11

1.6 Other OCS Oil- and Gas-Related Activities ......................................................................... 1-13

1.7 Other Pertinent Environmental Reviews or Documentation ................................................ 1-16

1.8 Format and Organization of the Multisale EIS ..................................................................... 1-19

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

2.1 Multisale NEPA Analysis ........................................................................................................ 2-3

2.2 Lease Sale Options, Alternatives, Mitigating Measures, and Issues..................................... 2-5

2.2.1 Lease Sale Options in the Five-Year Program............................................................ 2-5

2.2.2 Description of the Alternatives for This Multisale EIS.................................................. 2-6

2.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative)..................................................................................................... 2-6

2.2.2.2 Alternative B—Regionwide OCS Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area...... 2-8

2.2.2.3 Alternative C—Regionwide OCS Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale 

Area.............................................................................................................. 2-10

2.2.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, 

Live Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations .................................................................................. 2-11

2.2.2.5 Alternative E—No Action ............................................................................. 2-14

2.2.3 Alternatives and Deferrals Considered but Not Analyzed in Detail........................... 2-15

2.2.4 Mitigating Measures................................................................................................... 2-22

2.2.4.1 Proposed Prelease Mitigating Measures (Stipulations)............................... 2-23

2.2.4.2 Prelease Mitigating Measures (Stipulations) by Alternative ........................ 2-27

2.2.4.3 Postlease Mitigating Measures.................................................................... 2-27

2.2.5 Issues ......................................................................................................................... 2-29

2.2.5.1 Issues to be Analyzed.................................................................................. 2-29

2.2.5.2 Issues Considered but Not Analyzed........................................................... 2-32
xxxii Gulf of Mexico Multisale EIS

2.3 Comparison of Impacts by Alternative ................................................................................. 2-33

2.4 Summary of Impacts............................................................................................................. 2-35

2.4.1 Air Quality................................................................................................................... 2-35

2.4.2 Water Quality.............................................................................................................. 2-35

2.4.3 Coastal Habitats......................................................................................................... 2-36

2.4.3.1 Estuarine Systems (Wetlands and Seagrasses/Submerged 

Vegetation)................................................................................................... 2-36

2.4.3.2 Coastal Barrier Beaches and Associated Dunes......................................... 2-36

2.4.4 Deepwater Benthic Communities............................................................................... 2-37

2.4.5 Sargassum and Associated Communities................................................................. 2-37

2.4.6 Live Bottoms............................................................................................................... 2-38

2.4.6.1 Topographic Features.................................................................................. 2-38

2.4.6.2 Pinnacles and Low-Relief Features............................................................. 2-39

2.4.7 Fish and Invertebrate Resources............................................................................... 2-39

2.4.8 Birds ........................................................................................................................... 2-40

2.4.9 Protected Species...................................................................................................... 2-40

2.4.9.1 Marine Mammals.......................................................................................... 2-40

2.4.9.2 Sea Turtles................................................................................................... 2-41

2.4.9.3 Beach Mice .................................................................................................. 2-42

2.4.9.4 Protected Birds............................................................................................. 2-42

2.4.9.5 Protected Corals .......................................................................................... 2-43

2.4.10Commercial Fisheries ................................................................................................ 2-43

2.4.11Recreational Fishing .................................................................................................. 2-44

2.4.12Recreational Resources............................................................................................. 2-44

2.4.13Archaeological Resources ......................................................................................... 2-44

2.4.14Human Resources and Land Use (Including Environmental Justice)....................... 2-45

2.4.14.1 Land Use and Coastal Infrastructure........................................................... 2-45

2.4.14.2 Economic Factors ........................................................................................ 2-46

2.4.14.3 Social Factors (Including Environmental Justice)........................................ 2-46

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

3.1 Impact-Producing Factors and Scenario—Routine Operations............................................. 3-7

3.1.1 Resource Estimates and Timetables........................................................................... 3-7

3.1.2 Exploration and Delineation....................................................................................... 3-10

3.1.2.1 Geological and Geophysical Surveys.......................................................... 3-10

3.1.2.2 Exploration and Delineation Plans and Drilling............................................ 3-16

3.1.3 Offshore Development and Production...................................................................... 3-21

3.1.3.1 Development and Production Drilling .......................................................... 3-21

3.1.3.2 Offshore Production Systems ...................................................................... 3-26

3.1.3.3 Infrastructure Emplacement/Structure Installation and Commissioning 

Activities ....................................................................................................... 3-30

3.1.3.3.1 Bottom-Area Disturbance.......................................................... 3-33

3.1.3.3.2 Sediment Displacement ............................................................ 3-35

3.1.3.4 Infrastructure Presence................................................................................ 3-35

3.1.3.4.1 Anchoring .................................................................................. 3-35

3.1.3.4.2 Space-Use Requirements......................................................... 3-36

3.1.3.4.3 Structure Lighting ...................................................................... 3-37

3.1.3.5 Workovers and Abandonments ................................................................... 3-37

3.1.4 Transport.................................................................................................................... 3-38

3.1.4.1 Pipelines....................................................................................................... 3-38

3.1.4.2 Barges.......................................................................................................... 3-43

3.1.4.3 Oil Tankers................................................................................................... 3-44

3.1.4.4 Service Vessels............................................................................................ 3-46
Table of Contents xxxiii

3.1.4.5 Helicopters ................................................................................................... 3-47

3.1.4.6 Navigation Channels.................................................................................... 3-48

3.1.5 Discharges and Wastes ............................................................................................. 3-53

3.1.5.1 Operational Wastes and Discharges Generated by OCS Oil- and GasRelated Facilities.......................................................................................... 3-53

3.1.5.1.1 Produced Waters....................................................................... 3-61

3.1.5.1.2 Well-Treatment, Workover, and Completion Fluids.................. 3-63

3.1.5.1.3 Production Solids and Equipment............................................. 3-65

3.1.5.1.4 Bilge, Ballast, and Fire Water.................................................... 3-65

3.1.5.1.5 Cooling Water............................................................................ 3-66

3.1.5.1.6 Deck Drainage........................................................................... 3-66

3.1.5.1.7 Treated Domestic and Sanitary Wastes ................................... 3-67

3.1.5.1.8 Minor/Miscellaneous Discharges .............................................. 3-67

3.1.5.2 Operational Wastes and Discharges Generated by Service Vessels ......... 3-67

3.1.5.3 Onshore Disposal of Waste and Discharge Generated Offshore or 

Onshore........................................................................................................ 3-69

3.1.5.3.1 Onshore Disposal of Wastes Generated from OCS 

Oil- and Gas-Related Facilities ................................................. 3-69

3.1.5.3.2 Onshore Disposal and Storage Facilities Supporting 

OCS-Generated Operational Wastes ....................................... 3-70

3.1.5.3.3 Discharges from Onshore Support Facilities ............................ 3-70

3.1.5.3.4 Beach Trash and Debris ........................................................... 3-70

3.1.6 Decommissioning and Removal Operations ............................................................. 3-71

3.1.6.1 Structure Age and Idle Iron.......................................................................... 3-73

3.1.6.2 Rigs-to-Reefs Policy .................................................................................... 3-74

3.1.7 Coastal Infrastructure................................................................................................. 3-75

3.1.7.1 Construction Facilities.................................................................................. 3-77

3.1.7.1.1 Platform Fabrication Yards........................................................ 3-77

3.1.7.1.2 Shipbuilding and Shipyards....................................................... 3-78

3.1.7.1.3 Pipe-Coating Facilities and Yards............................................. 3-79

3.1.7.2 Support Facilities and Transportation.......................................................... 3-79

3.1.7.2.1 Service Bases and Ports........................................................... 3-79

3.1.7.2.2 Helicopter Hubs......................................................................... 3-82

3.1.7.2.3 Tanker Port Areas ..................................................................... 3-82

3.1.7.2.4 Barge Terminals........................................................................ 3-83

3.1.7.2.5 Pipeline Shore Facilities............................................................ 3-83

3.1.7.2.6 Navigation Channels ................................................................. 3-84

3.1.7.2.7 Waste Disposal Facilities .......................................................... 3-84

3.1.7.2.8 Natural Gas Storage Facilities .................................................. 3-84

3.1.7.3 Processing Facilities .................................................................................... 3-85

3.1.7.3.1 Gas Processing Plants.............................................................. 3-85

3.1.7.3.2 Refineries .................................................................................. 3-86

3.1.7.3.3 Onshore Liquefied Natural Gas Facilities ................................. 3-86

3.1.7.3.4 Petrochemical Plants................................................................. 3-87

3.1.8 Air Emissions.............................................................................................................. 3-87

3.1.8.1 Drilling .......................................................................................................... 3-88

3.1.8.2 Production .................................................................................................... 3-89

3.1.8.3 Vessel Support Operations and Activities during Offshore Oil and 

Gas Activities ............................................................................................... 3-89

3.1.8.4 Flaring and Venting...................................................................................... 3-89

3.1.8.5 Fugitive Emissions ....................................................................................... 3-90

3.1.8.6 Greenhouse Gases...................................................................................... 3-90

3.1.8.7 Decommissioning......................................................................................... 3-91
xxxiv Gulf of Mexico Multisale EIS

3.1.9 Noise .......................................................................................................................... 3-91

3.1.10New and Unusual Technology................................................................................... 3-94

3.2 Impact-Producing Factors and Scenario—Accidental Events ............................................. 3-95

3.2.1 Oil Spills ..................................................................................................................... 3-95

3.2.1.1 Past OCS Spills............................................................................................ 3-96

3.2.1.1.1 Trends in Reported Spill Volumes and Numbers...................... 3-96

3.2.1.1.2 Coastal Spills............................................................................. 3-98

3.2.1.2 Offshore Spills............................................................................................3-102

3.2.1.3 Characteristics of OCS Oil.........................................................................3-106

3.2.1.4 Transport and Fate of Offshore Spills........................................................3-107

3.2.1.5 Analysis of Offshore Spills ≥1,000 bbl .......................................................3-110

3.2.1.5.1 Overview of Spill Risk Analysis...............................................3-110

3.2.1.5.2 Trajectory Modeling for Offshore Spills ≥1,000 bbl.................3-111

3.2.1.5.3 Estimated Number of Offshore Spills ≥1,000 bbl and 

Probability of Occurrence........................................................3-113

3.2.1.5.4 Most Likely Source of Offshore Spills ≥1,000 bbl ...................3-115

3.2.1.5.5 Most Likely Size of an Offshore Spill ≥1,000 bbl ....................3-115

3.2.1.5.6 Length of Coastline Affected by Offshore Spills 

≥1,000 bbl................................................................................3-115

3.2.1.5.7 Risk Analysis by Resource......................................................3-116

3.2.1.5.8 Likelihood of an Offshore Spill ≥1,000 bbl Occurring and 

Contacting Coastal and Offshore Areas .................................3-116

3.2.1.6 Analysis of Offshore Spills <1,000 bbl .......................................................3-117

3.2.1.6.1 Estimated Number of Offshore Spills <1,000 bbl and 

Total Volume of Oil Spilled......................................................3-117

3.2.1.6.2 Most Likely Source and Type of Offshore Spills 

<1,000 bbl................................................................................3-117

3.2.1.6.3 Most Likely Size of Offshore Spills <1,000 bbl .......................3-117

3.2.1.6.4 Likelihood of an Offshore Spill <1,000 bbl Occurring and 

Contacting Coastal and Offshore Areas .................................3-117

3.2.1.7 Analysis of Coastal Spills...........................................................................3-118

3.2.1.7.1 Estimated Number and Most Likely Sizes of Coastal 

Spills ........................................................................................3-118

3.2.1.7.2 Likelihood of Coastal Spill Contact .........................................3-118

3.2.2 Losses of Well Control .............................................................................................3-118

3.2.3 Accidental Air Emissions..........................................................................................3-121

3.2.3.1 Hydrogen Sulfide and Sulfurous Petroleum ..............................................3-122

3.2.4 Pipeline Failures.......................................................................................................3-123

3.2.5 Vessel and Helicopter Collisions..............................................................................3-124

3.2.6 Chemical and Drilling-Fluid Spills ............................................................................3-126

3.2.7 Spill Response .........................................................................................................3-128

3.2.7.1 BSEE Spill-Response Requirements and Initiatives .................................3-128

3.2.7.1.1 Spill-Response Requirements.................................................3-128

3.2.7.1.2 Spill-Response Initiatives ........................................................3-130

3.2.7.2 Offshore Response, Containment, and Cleanup Technology...................3-130

3.2.7.2.1 Mechanical Cleanup................................................................3-133

3.2.7.2.2 Spill Treating Agents ...............................................................3-136

3.2.7.2.3 In-situ Burning .........................................................................3-139

3.2.7.2.4 Natural Dispersion...................................................................3-139

3.2.7.3 Onshore Response and Cleanup ..............................................................3-140

3.3 Cumulative Activities and OCS Oil and Gas Program Scenario........................................3-146

3.3.1 Cumulative OCS Oil and Gas Program Scenario....................................................3-146

3.3.1.1 Cumulative OCS Oil and Gas Program Projected Production ..................3-148
Table of Contents xxxv

3.3.1.2 Cumulative Geological and Geophysical Surveys.....................................3-149

3.3.1.3 Cumulative Exploration and Delineation Plans and Drilling ......................3-150

3.3.1.4 Cumulative Development and Production Drilling .....................................3-150

3.3.1.5 Infrastructure Emplacement/Structure Installation and 

Decommissioning Activities .......................................................................3-151

3.3.1.6 Infrastructure Presence..............................................................................3-152

3.3.1.7 Transport....................................................................................................3-152

3.3.1.8 Discharges and Wastes.............................................................................3-154

3.3.1.9 Decommissioning and Removal Operations .............................................3-154

3.3.1.10 Coastal Infrastructure.................................................................................3-154

3.3.1.11 Air Emissions .............................................................................................3-154

3.3.2 Non-OCS Oil- and Gas-Related Impact-Producing Factors....................................3-155

3.3.2.1 State Oil and Gas Activity ..........................................................................3-155

3.3.2.1.1 State Pipeline Infrastructure....................................................3-158

3.3.2.1.2 Artificial Reefs .........................................................................3-159

3.3.2.2 Marine Vessel Activity................................................................................3-160

3.3.2.2.1 Marine Transportation .............................................................3-160

3.3.2.2.2 Other Marine Vessel Traffic ....................................................3-162

3.3.2.2.3 Anchoring ................................................................................3-162

3.3.2.2.4 Tankering.................................................................................3-162

3.3.2.3 Non-OCS Oil- and Gas-Related Wastes and Discharges.........................3-162

3.3.2.3.1 Potentially Polluting Shipwrecks .............................................3-163

3.3.2.3.2 Discharges Associated with Military Activities ........................3-163

3.3.2.3.3 Historical Chemical Weapon Disposal Areas .........................3-165

3.3.2.3.4 Historical Industrial Waste Dumping Areas.............................3-165

3.3.2.3.5 Dredged Material Disposal......................................................3-166

3.3.2.3.6 Land-Based Discharges..........................................................3-168

3.3.2.3.7 Trash and Debris.....................................................................3-169

3.3.2.4 Non-OCS Oil- and Gas-Related Spills.......................................................3-169

3.3.2.5 Non-OCS Oil- and Gas- Related Air Emissions ........................................3-172

3.3.2.6 Other Non-OCS Oil- and Gas-Related Activities.......................................3-172

3.3.2.6.1 Military Warning and Water Test Areas ..................................3-172

3.3.2.6.2 Offshore Deepwater Ports and Nearshore Liquefied 

Natural Gas Terminals ............................................................3-174

3.3.2.6.3 Development of Gas Hydrates................................................3-176

3.3.2.6.4 Renewable Energy and Alternative Use .................................3-177

3.3.2.6.5 Aquaculture .............................................................................3-179

3.3.2.6.6 OCS Sand Borrowing..............................................................3-180

3.3.2.7 Noise from Non-OCS Oil- and Gas-Related Sources ...............................3-183

3.3.2.8 Coastal Environments................................................................................3-184

3.3.2.8.1 Sea-Level Rise and Subsidence.............................................3-184

3.3.2.8.2 Erosion ....................................................................................3-187

3.3.2.8.3 Coastal Restoration Programs................................................3-188

3.3.2.8.4 Saltwater Intrusion...................................................................3-195

3.3.2.8.5 Maintenance Dredging and Federal Channels .......................3-195

3.3.2.9 Natural Events and Processes ..................................................................3-197

3.3.2.9.1 Physical Oceanography ..........................................................3-197

3.3.2.9.2 Natural Seeps..........................................................................3-198

3.3.2.9.3 Hurricanes ...............................................................................3-199

3.3.2.9.4 Climate Change.......................................................................3-200

3.3.2.10 Mississippi River Hydromodification ..........................................................3-200

3.3.2.11 Mississippi River Eutrophication................................................................3-201
xxxvi Gulf of Mexico Multisale EIS

3.3.2.12 Hypoxia ......................................................................................................3-202

3.3.2.13 Sedimentation ............................................................................................3-204

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

4.1 Air Quality ............................................................................................................................. 4-11

4.1.1 Description of the Affected Environment ................................................................... 4-14

4.1.2 Environmental Consequences................................................................................... 4-22

4.1.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative)................................................................................................... 4-36

4.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area........................................................................................... 4-36

4.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area........................................................................................... 4-37

4.1.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, 

Live Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations .................................................................................. 4-37

4.1.2.5 Alternative E—No Action ............................................................................. 4-37

4.2 Water Quality........................................................................................................................ 4-37

4.2.1 Description of the Affected Environment ................................................................... 4-41

4.2.2 Environmental Consequences................................................................................... 4-43

4.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative)................................................................................................... 4-49

4.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area........................................................................................... 4-49

4.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area........................................................................................... 4-50

4.2.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, 

Live Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations .................................................................................. 4-50

4.2.2.5 Alternative E—No Action ............................................................................. 4-50

4.3 Coastal Habitats ................................................................................................................... 4-50

4.3.1 Estuarine Systems (Wetlands and Seagrass/Submerged Vegetation)..................... 4-50

4.3.1.1 Description of the Affected Environment ..................................................... 4-52

4.3.1.2 Environmental Consequences..................................................................... 4-56

4.3.1.2.1 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative)................................................................ 4-73

4.3.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area............................................. 4-74

4.3.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area............................... 4-74

4.3.1.2.4 Alternative D—Alternative D—Alternative A, B, or C, with 

the Option to Exclude Available Unleased Blocks Subject 

to the Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama 

Stipulations................................................................................ 4-74

4.3.1.2.5 Alternative E—No Action........................................................... 4-75
Table of Contents xxxvii

4.3.2 Coastal Barrier Beaches and Associated Dunes....................................................... 4-75

4.3.2.1 Description of the Affected Environment ..................................................... 4-76

4.3.2.2 Environmental Consequences..................................................................... 4-81

4.3.2.2.1 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative)................................................................ 4-91

4.3.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area............................................. 4-92

4.3.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area............................... 4-92

4.3.2.2.4 Alternative D—Alternative D—Alternative A, B, or C, with 

the Option to Exclude Available Unleased Blocks Subject 

to the Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations................................................................................ 4-93

4.3.2.2.5 Alternative E—No Action........................................................... 4-93

4.4 Deepwater Benthic Communities......................................................................................... 4-93

4.4.1 Description of the Affected Environment ................................................................... 4-98

4.4.1.1 Chemosynthetic Communities ...................................................................4-101

4.4.1.2 Deepwater Coral Communities..................................................................4-105

4.4.2 Environmental Consequences.................................................................................4-108

4.4.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative).................................................................................................4-119

4.4.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.........................................................................................4-119

4.4.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.........................................................................................4-120

4.4.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, 

Live Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations ................................................................................4-121

4.4.2.5 Alternative E—No Action ...........................................................................4-122

4.5 Sargassum and Associated Communities .........................................................................4-122

4.5.1 Description of the Affected Environment .................................................................4-126

4.5.2 Environmental Consequences.................................................................................4-129

4.5.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative).................................................................................................4-136

4.5.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.........................................................................................4-136

4.5.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.........................................................................................4-137

4.5.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, 

Live Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations ................................................................................4-137

4.5.2.5 Alternative E—No Action ...........................................................................4-137
xxxviii Gulf of Mexico Multisale EIS

4.6 Live Bottom Habitats ..........................................................................................................4-137

4.6.1 Topographic Features..............................................................................................4-139

4.6.1.1 Description of the Affected Environment ...................................................4-144

4.6.1.2 Environmental Consequences...................................................................4-148

4.6.1.2.1 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative)..............................................................4-156

4.6.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area...........................................4-157

4.6.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.............................4-157

4.6.1.2.4 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations..............................................................................4-157

4.6.1.2.5 Alternative E—No Action.........................................................4-158

4.6.2 Pinnacles and Low-Relief Features .........................................................................4-158

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

4.6.2.2 Environmental Consequences...................................................................4-169

4.6.2.2.1 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative)..............................................................4-180

4.6.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area...........................................4-181

4.6.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.............................4-181

4.6.2.2.4 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations..............................................................................4-182

4.6.2.2.5 Alternative E—No Action.........................................................4-183

4.7 Fishes and Invertebrate Resources ...................................................................................4-184

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

4.7.2 Environmental Consequences.................................................................................4-191

4.7.2.1 Alternatives A, B, C, and D ........................................................................4-202

4.7.2.2 Alternative E—No Action ...........................................................................4-203

4.8 Birds....................................................................................................................................4-203

4.8.1 Description of the Affected Environment .................................................................4-205

4.8.2 Environmental Consequences.................................................................................4-210

4.8.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative).................................................................................................4-219

4.8.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.........................................................................................4-221

4.8.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.........................................................................................4-221

4.8.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, Live 
Table of Contents xxxix

Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations ................................................................................4-222

4.8.2.5 Alternative E—No Action ...........................................................................4-223

4.9.1 Marine Mammals......................................................................................................4-228

4.9.1.1 Description of the Affected Environment ...................................................4-228

4.9.1.2 Environmental Consequences...................................................................4-240

4.9.1.2.1 Alternatives A, B, C, and D .....................................................4-263

4.9.1.2.2 Alternative E—No Action.........................................................4-265

4.9.2 Sea Turtles...............................................................................................................4-265

4.9.2.1 Description of the Affected Environment ...................................................4-265

4.9.2.2 Environmental Consequences...................................................................4-275

4.9.2.2.1 Alternative A, B, C, and D .......................................................4-292

4.9.2.2.2 Alternative E—No Action.........................................................4-294

4.9.3 Beach Mice (Alabama, Choctawhatchee, Perdido Key, and St. Andrew)...............4-294

4.9.3.1 Description of the Affected Environment ...................................................4-295

4.9.3.2 Environmental Consequences...................................................................4-295

4.9.3.2.1 Alternative A—Regionwide OCS Proposed Lease Sale 

(The Preferred Alternative)......................................................4-298

4.9.3.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area...........................................4-299

4.9.3.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.............................4-299

4.9.3.2.4 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations..............................................................................4-299

4.9.3.2.5 Alternative E—No Action.........................................................4-300

4.9.4 Protected Birds.........................................................................................................4-300

4.9.4.1 Description of the Affected Environment ...................................................4-300

4.9.4.2 Environmental Consequences...................................................................4-305

4.9.4.2.1 Alternative A—Regionwide OCS Proposed Lease Sale 

(The Preferred Alternative)......................................................4-308

4.9.4.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area...........................................4-308

4.9.4.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.............................4-308

4.9.4.2.4 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations..............................................................................4-308

4.9.4.2.5 Alternative E—No Action.........................................................4-309

4.9.5 Protected Corals ......................................................................................................4-309

4.9.5.1 Description of the Affected Environment ...................................................4-309

4.9.5.2 Environmental Consequences...................................................................4-310

4.9.5.2.1 Alternatives A, B, and C..........................................................4-311
xl Gulf of Mexico Multisale EIS

4.9.5.2.2 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations..............................................................................4-312

4.9.5.2.3 Alternative E—No Action.........................................................4-312

4.10 Commercial Fisheries.........................................................................................................4-313

4.10.1Description of the Affected Environment .................................................................4-314

4.10.2Environmental Consequences.................................................................................4-316

4.10.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative).................................................................................................4-320

4.10.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.........................................................................................4-321

4.10.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.........................................................................................4-321

4.10.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, 

Live Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations ................................................................................4-322

4.10.2.5 Alternative E—No Action ...........................................................................4-322

4.11 Recreational Fishing...........................................................................................................4-323

4.11.1Description of the Affected Environment .................................................................4-324

4.11.2Environmental Consequences.................................................................................4-331

4.11.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative).................................................................................................4-335

4.11.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed Lease 

Sale Area....................................................................................................4-335

4.11.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.........................................................................................4-336

4.11.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, Live 

Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations ................................................................................4-337

4.11.2.5 Alternative E—No Action ...........................................................................4-337

4.12 Recreational Resources .....................................................................................................4-338

4.12.1Description of the Affected Environment .................................................................4-339

4.12.2Environmental Consequences.................................................................................4-343

4.12.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative).................................................................................................4-353

4.12.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed Lease 

Sale Area....................................................................................................4-354

4.12.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.........................................................................................4-354

4.12.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, Live 

Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations ................................................................................4-355
Table of Contents xli

4.12.2.5 Alternative E—No Action ...........................................................................4-355

4.13 Archaeological Resources..................................................................................................4-356

4.13.1Description of the Affected Environment .................................................................4-357

4.13.1.1 Prehistoric ..................................................................................................4-357

4.13.1.2 Historic .......................................................................................................4-359

4.13.2Environmental Consequences.................................................................................4-362

4.13.2.1 Alternatives A, B, C, and D ........................................................................4-370

4.13.2.2 Alternative E—No Action ...........................................................................4-371

4.14 Human Resources and Land Use ......................................................................................4-371

4.14.1Land Use and Coastal Infrastructure.......................................................................4-371

4.14.1.1 Description of the Affected Environment ...................................................4-373

4.14.1.2 Environmental Consequences...................................................................4-379

4.14.1.2.1 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative)..............................................................4-390

4.14.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area...........................................4-392

4.14.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.............................4-392

4.14.1.2.4 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, 

Alabama, Stipulations..............................................................4-392

4.14.1.2.5 Alternative E—No Action.........................................................4-392

4.14.2Economic Factors ....................................................................................................4-393

4.14.2.1 Description of the Affected Environment ...................................................4-393

4.14.2.2 Environmental Consequences...................................................................4-398

4.14.2.2.1 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative)..............................................................4-407

4.14.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area...........................................4-411

4.14.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.............................4-414

4.14.2.2.4 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations..............................................................................4-418

4.14.2.2.5 Alternative E—No Action.........................................................4-418

4.14.3Social Factors (Including Environmental Justice)....................................................4-418

4.14.3.1 Description of the Affected Environment ...................................................4-420

4.14.3.2 Environmental Consequences...................................................................4-424

4.14.3.2.1 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative)..............................................................4-433

4.14.3.2.2 Alternative B—Regionwide OCS Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the 

Proposed Lease Sale Area .....................................................4-434
xlii Gulf of Mexico Multisale EIS

4.14.3.2.3 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.............................4-434

4.14.3.2.4 Alternative D—Alternative A, B, or C, with the Option to 

Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations..............................................................................4-435

4.14.3.2.5 Alternative E—No Action.........................................................4-435

4.14.3.3 Environmental Justice Determination ........................................................4-435

4.15 Unavoidable Adverse Impacts of a Proposed Action.........................................................4-436

4.16 Irreversible and Irretrievable Commitment of Resources ..................................................4-440

4.16.1Coastal Habitats.......................................................................................................4-440

4.16.2Biological Resources................................................................................................4-440

4.16.2.1 Threatened and Endangered Species.......................................................4-441

4.16.2.2 Fish and Invertebrate Resources, Deepwater Benthic Communities, 

Commercial Fisheries, and Recreational Fishing......................................4-441

4.16.3Archaeological Resources .......................................................................................4-441

4.16.4Oil and Gas Development........................................................................................4-441

4.16.5Loss of Human and Animal Life...............................................................................4-441

4.17 Relationship Between the Short-term Use of Man’s Environment and the Maintenance and 

Enhancement of Long-term Productivity............................................................................4-442

4.17.1Short-Term Use........................................................................................................4-442

4.17.2Relationship to Long-Term Productivity...................................................................4-443
Table of Contents xliii

Volume II 

Page

LIST OF FIGURES..............................................................................................................................xvii

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

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

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

5.2 Notice of Intent to Prepare an EIS and Call for Information................................................... 5-4

5.3 Area ID Memorandum ............................................................................................................ 5-4

5.4 Development of the Draft Multisale EIS ................................................................................. 5-4

5.4.1 Summary of Scoping Comments ................................................................................. 5-6

5.4.2 Summary of Comments Received in Response to the Call for Information................ 5-9

5.4.3 Additional Public Input Opportunities......................................................................... 5-10

5.4.4 Cooperating Agencies................................................................................................ 5-10

5.5 Distribution of the Draft Multisale EIS for Review and Comment ........................................ 5-11

5.6 Coastal Zone Management Act............................................................................................ 5-15

5.7 Endangered Species Act...................................................................................................... 5-16

5.8 Magnuson-Stevens Fishery Conservation and Management Act ....................................... 5-16

5.9 National Historic Preservation Act........................................................................................ 5-17

5.10 Government-to-Government ................................................................................................ 5-18

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

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

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

APPENDICES

Appendix A Postlease Permitting and Approval Processes .............................................. A-3

Appendix B Commonly Applied Mitigating Measures........................................................ B-3

Appendix C Cooperating Agency Memorandum of Agreement......................................... C-3

Appendix D Proposed Prelease Mitigating Measures (Stipulations)................................. D-3

Appendix E Oil Spill Risk Analysis Figures........................................................................ E-3

Appendix F Species not Considered Further..................................................................... F-3

Appendix G State Coastal Management Programs ........................................................... G-3

KEYWORD INDEX................................................................................................................Keywords-3

List of Figures xlv

LIST OF FIGURES

Page

Figure 1-1. Proposed Regionwide Lease Sale Area Combining the Western, Central, and 

Eastern Planning Areas. ................................................................................................ 1-4

Figure 1-2. OCS Oil and Gas Program Development Process........................................................ 1-6

Figure 1-3. Planning for the Five-Year Program. ............................................................................. 1-8

Figure 1-4. Planning for Regional OCS Oil and Gas Lease Sales................................................... 1-8

Figure 1-5. Supplemental Approach Showing the Tiering Relationships for Proposed Gulf 

of Mexico Lease Sales................................................................................................. 1-10

Figure 1-6. BOEM’s Consultation Partners for Specific Federal Regulations................................ 1-12

Figure 1-7. BOEM’s Integrated Approach for Incorporating Applied Science into 

Decisionmaking............................................................................................................ 1-14

Figure 2-1. Proposed Regionwide Lease Sale Area, Encompassing the Available Unleased 

Blocks within All Three Planning Areas. ........................................................................ 2-7

Figure 2-2. Proposed Lease Sale Area for Alternative B, Excluding the Available Unleased 

Blocks in the WPA.......................................................................................................... 2-9

Figure 2-3. Proposed Lease Sale Area for Alternative C, Excluding the Available Unleased 

Blocks in the CPA and EPA. ........................................................................................ 2-10

Figure 2-4. Identified Topographic Features, Pinnacle Trend, and Blocks South of Baldwin 

County, Alabama, Stipulation Blocks in the Gulf of Mexico......................................... 2-12

Figure 2-5. Example of Excluded Blocks under Alternative D. ...................................................... 2-13

Figure 2-6. Federal OCS Blocks Subject to the Gulf Islands National Seashore Information to 

Lessees and Operators................................................................................................ 2-18

Figure 2-7. Military Warning Areas and Eglin Water Test Areas in the Gulf of Mexico. ................ 2-24

Figure 3-1. Offshore Subareas in the Gulf of Mexico....................................................................... 3-8

Figure 3-2. Typical Exploration and Production Timeline for Offshore Oil and Gas Drilling.......... 3-10

Figure 3-3. General Well Schematic. .............................................................................................. 3-18

Figure 3-4. Number of Exploration and Delineation Wells Drilled over the Course of a Proposed 

Action under Alternative A for 50 Years....................................................................... 3-20

Figure 3-5. Number of Production Wells Drilled over the Course of a Proposed Action under 

Alternative A for 50 Years. ........................................................................................... 3-25

Figure 3-6. Offshore Production Systems. ..................................................................................... 3-26

Figure 3-7. Number of Production Structures and Service Vessels Operating over the Course 

of a Proposed Action under Alternative A for 50 Years............................................... 3-33

Figure 3-8. Gulfwide OCS Oil- and Gas-Related Service Bases and Major Waterways............... 3-52

Figure 3-9. Water Quality Jurisdictional Boundaries for USEPA Regions 4 and 6........................ 3-54

Figure 3-10. Onshore Infrastructure. ................................................................................................ 3-76

Figure 3-11. OCS-Related Ports and Waterways in the Gulf of Mexico.......................................... 3-81

Figure 3-12. The Oil Spill Risk Analysis Model Process. ...............................................................3-111

Figure 3-13. OCS Oil and Gas Production Between 2003 and 2013.............................................3-149

Figure 3-14. Number of Production Structures Installed and Decommissioned in Past Programs 

and the Range of Future Projections that May Occur as a Result of All Past, 

Present, and Future Actions. .....................................................................................3-151

Figure 3-15. 2015 Gulf of Mexico Hypoxic Zone. ...........................................................................3-203

Figure 4-1. Air Quality Areas of Influence (Texas, Louisiana, Mississippi, Alabama, and 

Florida) in the Gulf of Mexico OCS Region with the Class I Areas, Air Quality 

Jurisdiction Line, and OCS Lease Blocks.................................................................... 4-14

Figure 4-2. Ozone Nonattainment Status in the Gulf of Mexico Region in Louisiana and Texas.. 4-18

Figure 4-3. 2011 Platform NOx Emissions...................................................................................... 4-20

Figure 4-4. 2011 Non-Platform NOx Emissions.............................................................................. 4-20

Figure 4-5. 2011 Platform VOC Emissions .................................................................................... 4-21
xlvi Gulf of Mexico Multisale EIS

Figure 4-6. 2011 Non-Platform VOC Emissions............................................................................. 4-21

Figure 4-7. Year 2011 Gulfwide Emission Inventory Results for Total Platform and 

Non-Platform Criteria Pollutant Emissions (TPY). ....................................................... 4-22

Figure 4-8. Year 2011 Gulfwide Emission Inventory Results for Total Platform and 

Non-Platform Greenhouse Gas Emissions (TPY). ...................................................... 4-22

Figure 4-9. 2011 Criteria Pollutant Emissions (TPY) from Platform Sources. ............................... 4-26

Figure 4-10. 2011 Greenhouse Gases (TPY) from Platform Sources. ............................................ 4-26

Figure 4-11. Seagrass Locations of the Northern Gulf of Mexico.................................................... 4-55

Figure 4-12. Deepwater Coral Records from NOAA’s National Deep-Sea Coral and Sponge 

Database...................................................................................................................... 4-99

Figure 4-13. Estimated Distribution of Known Deepwater Benthic Communities in the Gulf of 

Mexico as of 2015. .....................................................................................................4-102

Figure 4-14. BOEM’s Water Bottom Seismic Anomaly Database Showing Grouped Anomaly 

Categories Thought Likely to Support Deepwater Benthic Communities and 

Those That Generally Do Not ....................................................................................4-104

Figure 4-15. Example of a Predictive Habitat Suitability Model for Selected Deepwater, 

Framework-Forming Scleractinian Corals .................................................................4-107

Figure 4-16. Sargassum Loop System...........................................................................................4-125

Figure 4-17. Lease Blocks Subject to the Topographic Features and Live Bottom (Pinnacle 

Trend) Stipulations. ....................................................................................................4-138

Figure 4-18. Ecological Representation of Common Features on Topographic Features in the 

Gulf of Mexico. ...........................................................................................................4-140

Figure 4-19. General Location of the Pinnacle Trend (A), Multibeam Bathymetry and Named 

Reef Areas (B), and an Exaggerated Vertical Relief Profile of Rough Tongue 

Reef (C)......................................................................................................................4-166

Figure 4-20. Migration Routes for Trans-Gulf Migratory Birds in the Presence of an Eastern 

Continental High.........................................................................................................4-208

Figure 4-21. Migration Routes for Trans-Gulf Migratory Birds in the Presence of a Bermuda 

High. ...........................................................................................................................4-209

Figure 4-22. Platform Density and Spring Migration Routes for Trans-Gulf Migratory Birds.........4-209

Figure 4-24. Gulf Islands National Seashore. ................................................................................4-343

Figure 4-25. Historical Structure Locations near Horn and Petit Bois Islands...............................4-346

Figure 4-26. Photograph of Remaining OCS Structures taken from Petit Bois Island Looking 

South ..........................................................................................................................4-346

Figure 4-27. Economic Land Use Patterns. ...................................................................................4-377

Figure 4-28. Historical Land Loss in Louisiana, 1932-2010...........................................................4-388

Figure 4-29. Moderate Scenario: Projected Land Loss in Louisiana............................................4-389

Figure 4-30. Less Optimistic Scenario: Projected Land Loss in Louisiana...................................4-389

Figure 4-31. Population of BOEM’s Economic Impact Areas in the Gulf of Mexico. .....................4-421

Figure 4-32. Percentage of Poverty in Texas and Louisiana.........................................................4-422

Figure 4-33. Percentage of Poverty in Mississippi, Alabama, and Florida. ...................................4-423

Figure 4-34. Percentage of Minority Populations in Texas and Louisiana.....................................4-424

Figure 4-35. Percentage of Minority Populations in Mississippi, Alabama, and Florida................4-424

Figure 5-1. Timeline for the Development of This Multisale EIS...................................................... 5-3

Figure E-1. The Oil Spill Risk Analysis Domain............................................................................... E-4

Figure E-2. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

the Shoreline (counties and parishes) as a Result of Alternative A. ............................ E-4

Figure E-3. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

the Shoreline (counties and parishes) as a Result of Alternative A. ............................ E-5

Figure E-4. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

the Shoreline (counties and parishes) as a Result of Alternative B. ............................ E-5

Figure E-5. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

the Shoreline (counties and parishes) as a Result of Alternative B. ............................ E-6
List of Figures xlvii

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

the Shoreline (counties and parishes) as a Result of Alternative C............................. E-6

Figure E-7. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

the Shoreline (counties and parishes) as a Result of Alternative C............................. E-7

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

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative A............................................................................................................. E-7

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

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative A............................................................................................................. E-8

Figure E-10. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative A............................................................................................................. E-8

Figure E-11. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative A............................................................................................................. E-9

Figure E-12. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative B............................................................................................................. E-9

Figure E-13. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative B........................................................................................................... E-10

Figure E-14. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative B........................................................................................................... E-10

Figure E-15. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative B........................................................................................................... E-11

Figure E-16. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative C........................................................................................................... E-11

Figure E-17. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative C........................................................................................................... E-12

Figure E-18. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative C........................................................................................................... E-12

Figure E-19. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative C........................................................................................................... E-13
xlviii Gulf of Mexico Multisale EIS

Figure E-20. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

and 30 Days State Offshore Waters as a Result of Alternative A, B, or C................. E-13
List of Tables xlix

LIST OF TABLES

Page

Table 2-1. Applicable Stipulations by Alternative.......................................................................... 2-27

Table 2-2. Alternative Comparison Matrix..................................................................................... 2-33

Table 3-1. Projected Oil and Gas in the Gulf of Mexico OCS......................................................... 3-8

Table 3-2. Offshore Scenario Activities Related to a Single Lease Sale for Alternative A, B, 

or C from 2017 through 2066......................................................................................... 3-9

Table 3-3. Oil Transportation Scenario under Alternative A, B, or C............................................ 3-38

Table 3-4. Existing Coastal Infrastructure Related to OCS Oil- and Gas-Related Activities 

in the Gulf of Mexico. ................................................................................................... 3-39

Table 3-5. OCS Pipeline Landfalls Installed from 1996 to 2014................................................... 3-43

Table 3-6. Waterway Length, Depth, Traffic, and Number of Trips for 2012................................ 3-49

Table 3-7. Pollution-Related Incidents of Noncompliance Issued from 1986 to the Present. ...... 3-56

Table 3-8. National Pollutant Discharge Elimination System Inspections from 1999 through 

2014.............................................................................................................................. 3-57

Table 3-9. Annual Volume of Produced Water Discharged by Depth (millions of bbl)................. 3-63

Table 3-10. OCS Oil- and Gas-Related Service Bases. ................................................................. 3-80

Table 3-11. Annual Summary of Number and Total Volume of Oil Spilled into the Gulf of 

Mexico, 2001-2015....................................................................................................... 3-96

Table 3-12. Spill Rates for Petroleum Spills ≥1,000 Barrels from OCS Platforms and Pipelines, 

1964 through 2010....................................................................................................... 3-98

Table 3-13. Historic Spill Source, Location, and Characteristics of a Maximum Spill for Coastal 

Waters and Offshore Waters. ....................................................................................3-100

Table 3-14. Petroleum1 Spills ≥1,000 Barrels from United States OCS Platforms, 1964-2015...3-103

Table 3-15. Petroleum1 Spills ≥1,000 Barrels from United States OCS Pipelines, 1964-2015. ..3-105

Table 3-16. Properties and Persistence by Oil Component Group...............................................3-107

Table 3-17. Probability (percent chance) of a Particular Number of Offshore Spills ≥1,000 

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

Alternative A, B, or C..................................................................................................3-112

Table 3-18. Mean Number and Sizes of Spills Estimated to Occur in OCS Offshore Waters 

from an Accident Related to Rig/Platform and Pipeline Activities Supporting Each 

Alternative Over a 50-Year Time Period....................................................................3-113

Table 3-19. Oil-Spill Occurrence Probability Estimates for Offshore Spills ≥1,000 Barrels 

Resulting from Each Alternative (2017-2066) and the Cumulative OCS Oil and 

Gas Program (2017-2086). ........................................................................................3-114

Table 3-20. Oil-Spill Occurrence Probability Estimates for Offshore Spills ≥10,000 Barrels 

Resulting from Each Alternative (2017-2066) and the Cumulative OCS Oil and 

Gas Program (2017-2086). ........................................................................................3-114

Table 3-21. Number and Volume of Chemical and Synthetic-Based Fluid Spills for 10-49 

Barrels and >50 Barrels in the Gulf of Mexico from 2007 through 2014...................3-127

Table 3-22. Primary Cleanup Options Used during the Deepwater Horizon Response...............3-131

Table 3-23. Future Activity Projections Associated with the Cumulative OCS Oil and Gas 

Program (2017-2086), Including All Future Activities that are Projected to Occur 

from Past, Proposed, and Future Lease Sales..........................................................3-147

Table 3-24. Future Oil Transportation Projections Associated with the Cumulative OCS Oil and 

Gas Program (2017-2086), Including All Future Transportation that is Projected to 

Occur from Past, Proposed, and Future Lease Sales...............................................3-153

Table 3-25. Number of Vessel Calls at U.S. Gulf Ports Between 2002 and 2011........................3-161

Table 3-26. Quantities of Dredged Materials Disposed of in Ocean Dredged-Material Disposal 

Sites Between 2004 and 2013...................................................................................3-167
l Gulf of Mexico Multisale EIS

Table 3-27. Average Annual Inputs of Petroleum Hydrocarbons to Coastal Waters of the 

Gulf of Mexico, 1990-1999.........................................................................................3-170

Table 3-28. Average Annual Inputs of Petroleum Hydrocarbons to Offshore Waters of the 

Gulf of Mexico, 1990-1999.........................................................................................3-171

Table 3-29. Projected OCS Sand Resource Needs for Planned Restoration Projects. ...............3-180

Table 3-30. Hurricane Landfalls in the Northern Gulf of Mexico from 1995 through 2015...........3-199

Table 3-31. Oil Spilled from Pipelines on the Federal OCS, 2002-2009. .....................................3-200

Table 4-1. Air Quality Impact-Producing Factors. ......................................................................... 4-12

Table 4-2. National Ambient Air Quality Standards. ..................................................................... 4-16

Table 4-3. Water Quality Impact-Producing Factors..................................................................... 4-39

Table 4-4. Estuarine Systems Impact-Producing Factors............................................................. 4-51

Table 4-5. Coastal Barrier Beaches and Associated Dunes Impact-Producing Factors.............. 4-75

Table 4-6. Deepwater Benthic Communities Impact-Producing Factors...................................... 4-96

Table 4-7. Sargassum and Associated Communities Impact-Producing Factors. .....................4-123

Table 4-8. Topographic Features Impact-Producing Factors. ....................................................4-141

Table 4-9. Pinnacles and Low-Relief Features Impact-Producing Factors. ...............................4-159

Table 4-10. Fish and Invertebrate Resources Impact-Producing Factors....................................4-186

Table 4-11. Birds Impact-Producing Factors.................................................................................4-204

Table 4-12. Species within the Gulf of Mexico That Are Protected Under the Endangered 

Species Act and/or the Marine Mammal Protection Act. ...........................................4-224

Table 4-14. Best Available Population Estimates for Marine Mammal Species in the Northern 

Gulf of Mexico. ...........................................................................................................4-229

Table 4-15. Commercial Fisheries Impact-Producing Factors......................................................4-313

Table 4-16. Landings Revenues: Landings Revenue by Species and State...............................4-315

Table 4-17. Recreational Fishing Impact Producing Factors........................................................4-323

Table 4-18. CPA and EPA Effort Data: Angler Trips in the Gulf of Mexico. ................................4-325

Table 4-19. CPA and EPA Catch Data: Fish Species Caught by Recreational Anglers from 

2008 through 2013 in Louisiana, Mississippi, and Alabama Combined....................4-327

Table 4-20. CPA and EPA Catch Data: Fish Species Caught by Recreational Anglers from 

2008 through 2013 in West Florida............................................................................4-327

Table 4-21. Texas Effort Data: Number of Angler Trips from 2009 through 2014.......................4-329

Table 4-22. Texas Catch Data: Top Species Landed by Recreational Fishermen. ....................4-330

Table 4-23. Recreational Resources Impact-Producing Factors..................................................4-338

Table 4-24. Recreational and Tourism Employment and Value-Added in BOEM's Economic 

Impact Areas in 2013. ................................................................................................4-340

Table 4-25. Archaeological Surveys and Resources Identified, 2009-2014.................................4-360

Table 4-26. Land Use and Coastal Infrastructure Impact-Producing Factors. .............................4-373

Table 4-27. Economic and Demographic Information for BOEM's Economic Impact Areas 

in 2015........................................................................................................................4-394

Table 4-28. Sales Volumes, Sales Values, and Revenues...........................................................4-397

Table 4-29. Cumulative Low: MAG-PLAN Industry Expenditure Impacts. ..................................4-403

Table 4-30. Cumulative High: MAG-PLAN Industry Expenditure Impacts...................................4-404

Table 4-31. Economic and Demographic Information for BOEM's Economic Impact Areas 

in 2050........................................................................................................................4-406

Table 4-32. Gulf of Mexico Single Low: MAG-PLAN Industry Expenditure Impacts. ..................4-408

Table 4-33. Gulf of Mexico Single High: MAG-PLAN Industry Expenditure Impacts. .................4-409

Table 4-34. CPA Single Low: MAG-PLAN Industry Expenditure Impacts...................................4-412

Table 4-35. CPA Single High: MAG-PLAN Industry Expenditure Impacts. .................................4-413

Table 4-36. WPA Single Low: MAG-PLAN Industry Expenditure Impacts. .................................4-415

Table 4-37. WPA Single High: MAG-PLAN Industry Expenditure Impacts. ................................4-417

Table B-1. Commonly Applied or “Standard” Mitigating Measures................................................ B-5 
Abbreviations and Acronyms li

ABBREVIATIONS AND ACRONYMS

°C degree Celsius

°F degree Fahrenheit

μg microgram

μg/g micrograms/gram

2012-2017 Five-Year 

Program

Proposed Final Outer Continental Shelf Oil & Gas Leasing Program: 

2012-2017

2012-2017 WPA/CPA 

Multisale EIS

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; 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

Area ID Area Identification

ASLM Assistant Secretary of the Interior for Land and Minerals

bbl barrel

Bbbl billion barrels

Bcf billion cubic feet

BBO billion barrels of oil

BOEM Bureau of Ocean Energy Management

BOEMRE Bureau of Ocean Energy Management, Regulation and Enforcement

BOP blowout preventer

BP Before Present

BSEE Bureau of Safety and Environmental Enforcement

BTEX benzene, toluene, ethylbenzene, and xylene

Call Call for Information

Cd cadmium

CD Consistency Determination

CEI Coastal Environments, Inc.

CEQ Council on Environmental Quality

CEWAF chemically enhanced (dispersed) water-accommodated fractions

CFR Code of Federal Regulations

CG Coast Guard (also: USCG)

CH4 methane

CIAP Coastal Impact Assistance Program

CMP Coastal Management Program
lii Gulf of Mexico Multisale EIS

CO carbon monoxide

CO2 carbon dioxide

COE Corps of Engineers (U.S. Army)

CPA Central Planning Area

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

CPRA Coastal Protection and Restoration Authority

Cu copper

CSA Continental Shelf Associates

CYP1A cytochrome P-4501A

CWPPRA Coastal Wetlands Planning, Protection and Restoration Act

CZMA Coastal Zone Management Act

dB decibel

dB re: 1μPa decibels referenced 1 microPascal

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

DOT Department of Transportation (U.S.) (also: USDOT)

DMR discharge monitoring report

DPP development and production plan

Draft Proposed Program 2017-2022 OCS Oil and Gas Leasing: Draft Proposed Program

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

ESI Environmental Sensitivity Index

et al. and others

et seq. and the following

FERC Federal Energy Regulatory Commission

Five-Year Program 2017-2022 Outer Continental Shelf Oil & Gas Leasing: Proposed Program

(also: 2017-2022 Five-Year Program)

Five-Year Program EIS Outer Continental Shelf Oil and Gas Leasing Program: 2017-2022, 

Final Environmental Impact Statement

FL Florida

FGBNMS Flower Garden Banks National Marine Sanctuary

FPSO floating production, storage, and offloading system

FR Federal Register
Abbreviations and Acronyms liii

ft feet

FWS Fish and Wildlife Service

G&G geological and geophysical

g gram

GAP General Activities Plan

GIS Geographic Information System

GIWW Gulf Intracoastal Waterway

GMFMC Gulf of Mexico Fishery Management Council

GOM Gulf of Mexico

GPS global positioning system

GUIS Gulf Islands National Seashore

GWEI Gulfwide Emission Inventory

H2S hydrogen sulfide

ha hectare

HAPC habitat area of particular concern

Hg mercury

HRG high-resolution geophysical

i.e. that is

km kilometer

IPCC Intergovernmental Panel on Climate Change

ITL Information to Lessees and Operators

LA Louisiana

lb pound

LCA Louisiana Coastal Area

LNG liquefied natural gas

LOOP Louisiana Offshore Oil Port

m meter

MAG-PLAN MMS Alaska-GOM Model Using IMPLAN

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

Mcf thousand cubic feet

MCV modular capture vessel

mg/L milligrams/liter

mi mile

mm millimeter

MMbbl million barrels

MMcf million cubic feet

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MODU mobile offshore drilling unit

MOU Memorandum of Understanding

MS Mississippi

MWCC Marine Well Containment Company

N2O nitrous oxide
liv Gulf of Mexico Multisale EIS

NAAQS National Ambient Air Quality Standards

NASA National Aeronautics and Space Administration

NAZ narrow azimuth

NCP National Oil and Hazardous Substances Pollution Contingency Plan 

NEPA National Environmental Policy Act

NGL natural gas liquids

NHPA National Historic Preservation Act

NMFS National Marine Fisheries Service

nmi nautical-mile

NO2 nitrogen dioxide

NOx nitrogen oxides

NOA Notice of Availability

NOAA National Oceanic and Atmospheric Administration

NOI Notice of Intent to Prepare an EIS

NOS National Ocean Service

NPDES National Pollutant and Discharge Elimination System

NPS National Park Service

NRC National Research Council

NRDA Natural Resource Damage Assessment

NTL Notice to Lessees and Operators

O3 ozone

OBF oil-based fluid

OCD Offshore and Coastal Dispersion

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/service vessel

P.L. Public Law

PAH polycyclic aromatic hydrocarbons

Pb lead

PBR Potential Biological Removal

PDARP/PEIS Programmatic Damage Assessment and Restoration Plan 

and Final Programmatic Environmental Impact Statement

pH potential of hydrogen

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

ppm parts per million

PSD Prevention of Significant Deterioration
Abbreviations and Acronyms lv

psi pounds per square inch

RESTORE Act Resources and Ecosystems Sustainability, Tourist Opportunities, and 

Revived Economies of the Gulf Coast States Act

ROD Record of Decision

RSDFO Regional Supervisor for District Field Operations

SAP Site Assessment Plan

SBF synthetic-based fluid

SBM synthetic-based mud

Secretary Secretary of the Interior

SEL sound exposure level

SMART Special Monitoring of Applied Response Technologies

SO2 sulphur dioxide

SOx sulphur oxides

Stat. Statute

SURF subsea umbilical, risers, and flowlines

sVGP Small Vessel General Permit

Tcf trillion cubic feet

TLP tension-leg platform

Trustee Council Natural Resource Damage Assessment Trustee Council

TX Texas

U.S. United States

U.S.C. United States Code

UME unusual mortality event

UNCLOS United Nations Convention on the Law of the Sea

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 (also: DOT)

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

WAZ wide azimuth

WBF water-based fluid

WPA Western Planning Area

yd yard

Zn zinc

Conversion Chart lvii

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 (lb)

CHAPTER 1 

PURPOSE OF AND NEED FOR THE PROPOSED ACTIONS

Purpose of and Need for the Proposed Actions 1-3 

What’s in This Chapter

• The Bureau of Ocean Energy Management (BOEM) proposes 10 regionwide Gulf of 

Mexico lease sales: one per year in August 2017 through 2021 and one per year in March 

2018 through 2022.

• These lease sales are being proposed pursuant to the Outer Continental Shelf Lands Act 

of 1953 (OCSLA) and are intended to help meet the Nation’s energy needs in the next 

5 years.

• The need for the proposed actions is to manage the development of Outer Continental 

Shelf (OCS) energy resources in an environmentally and economically responsible 

manner. Oil from the Gulf of Mexico OCS would contribute to meeting domestic demand 

and enhance national economic security.

• Pursuant to the OCSLA’s staged leasing process, for each lease sale proposed in the 

Five-Year Program, BOEM makes individual decisions on whether and how to proceed 

with each proposed lease sale.

• Following an established, robust decisionmaking process that invites input from numerous 

interested parties and the general public, BOEM produced this 2017-2022 Gulf of Mexico 

Multisale Environmental Impact Statement (Multisale EIS) to use as the basis for the first 

proposed lease sale and for supplemental NEPA reviews for the subsequent proposed 

lease sales.

• This Multisale EIS explains the environmental considerations and potential mitigations to 

assess the potential environmental consequences of the proposed actions and 

alternatives.

1 PURPOSE OF AND NEED FOR THE PROPOSED ACTIONS

The Bureau of Ocean Energy Management 

(BOEM) proposes to conduct 10 regionwide Gulf of 

Mexico (GOM) oil and gas lease sales, which are 

tentatively scheduled in the Proposed Outer 

Continental Shelf Oil & Gas Leasing Program: 

2017-2022 (Five-Year Program; USDOI, BOEM, 

2016a). Five regionwide lease sales are tentatively 

scheduled in August of each year from 2017 through 

2021 and five regionwide lease sales are tentatively 

scheduled in March of each year from 2018 through 

2022. The lease sales proposed in the GOM in the Five-Year Program are regionwide lease sales 

comprised of the Western, Central, and a small portion of the Eastern Planning Areas (WPA, CPA, 

and EPA, respectively) not subject to Congressional moratorium. These planning areas are located 

off the States of Texas, Louisiana, Mississippi, Alabama, and Florida (Figure 1-1). Even though the 

Five-Year Program includes regionwide lease sales, any individual lease sale could still be scaled 

back during the prelease sale process to conform more closely to the separate planning area model 

used in the Proposed Final Outer Continental Shelf Oil & Gas Leasing Program: 2012-2017

(2012-2017 Five-Year Program; USDOI, BOEM, 2012a), should circumstances warrant.

Proposed 2017-2022 

Gulf of Mexico OCS Region 

Lease Sale Schedule

Lease Sale Number Year

249 2017

250 and 251 2018

252 and 253 2019

254 and 256 2020

257 and 259 2021

261 2022
1-4 Gulf of Mexico Multisale EIS

“It is hereby declared to be the 

policy of the United States that ... 

the Outer Continental Shelf is a 

vital national resource held by the 

Federal Government for the public, 

which should be made available for 

expeditious and orderly 

development, subject to 

environmental safeguards, in a 

manner which is consistent with 

the maintenance of competition 

and other national needs."

OCSLA, 43 U.S.C. §§ 1331 et seq.

Figure 1-1. Proposed Regionwide Lease Sale Area Combining the Western, Central, and Eastern 

Planning Areas.

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

responsible for the leasing of submerged Outer Continental Shelf (OCS) lands and for the 

supervision of certain 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 include the following: leasing; oversight of exploration and 

development; plan administration; environmental studies; National Environmental Policy Act (NEPA) 

analyses; resource evaluation, economic, and the Marine Minerals Program analyses; and the 

renewable energy program. The Bureau of Safety and Environmental Enforcement (BSEE) is 

responsible for enforcing safety and environmental regulations. The functions of BSEE include all 

field operations, including permitting for drilling and 

decommissioning, research, inspections, offshore regulatory 

programs, oil-spill response, and training and environmental 

compliance functions.

The proposed lease sales would 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.

1.1 PURPOSE OF THE PROPOSED ACTIONS

The Outer Continental Shelf Lands Act of 1953, as 

amended (43 U.S.C. §§ 1331 et seq.), hereafter referred to 

as OCSLA, establishes the Nation’s policy for managing the 
Purpose of and Need for the Proposed Actions 1-5 

vital energy and mineral resources of the OCS. Section 18 of OCSLA requires the Secretary to 

prepare and maintain a schedule of proposed OCS oil and gas lease sales determined to “best meet 

national energy needs for the 5-year period following its approval or reapproval” (43 U.S.C. § 1344). 

The Five-Year Program establishes a schedule that the U.S. Department of the Interior (USDOI or 

DOI) will use as a basis for considering where and when leasing might be appropriate over a 5-year 

period.

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

contain economically recoverable oil and gas resources in accordance with OCSLA.

1.2 NEED FOR THE PROPOSED ACTIONS

The need for the proposed actions is to manage the development of the OCS energy 

resources in an environmentally and economically responsible manner. Oil serves as the feedstock 

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

petrochemicals. Oil from the Gulf of Mexico OCS contributes to meeting domestic demand and 

enhances national economic security.

In 2014, the United States (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). Over the next 20 years, the Energy 

Information Administration expects the U.S. to rely on more oil and natural gas to meet its energy 

demands, even as alternative sources of energy provide an increasing share of U.S. energy needs. 

The Energy Information Administration projects that consumption of liquid fuels will decrease slightly 

through 2040, but consumption of natural gas would increase by a greater amount over the same 

period.

The surge in production from large onshore tight-formation plays has also impacted the U.S. 

energy market by keeping domestic natural gas prices far below benchmark prices in many other 

parts of the world, converting the U.S. into a net exporter of natural gas. Companies are planning 

and constructing liquefied natural gas (LNG) export terminals, hoping to take advantage of prices 

that can be more than twice the level of U.S. prices. Less expensive natural gas has also reduced 

manufacturing energy costs. Many companies are beginning or increasing U.S operations or 

returning manufacturing from overseas. This natural gas renaissance is helping to curb the longterm decline in U.S. manufacturing jobs and is providing a competitive advantage for the U.S. 

manufacturing industry. The advances in tight oil production also provide more timely responses to 

changing prices and other conditions, helping to mitigate market swings in supply and prices. 

Conversely, projects like those on the OCS provide a fairly stable source of oil and gas that is not as 

susceptible to changes in markets or early assumptions about undiscovered resources, prices, 

technology, and recovery rates. This overall stability allows for long-term planning for infrastructure 

and other needs.
1-6 Gulf of Mexico Multisale EIS

Since the U.S. is expected to continue to rely on oil and natural gas to meet its energy 

needs, the proposed actions would contribute to meeting domestic demand. The OCS is a major 

long-term supplier of crude oil and natural gas, and the Gulf of Mexico OCS region has the greatest 

resource potential of the four OCS regions in the United States. Crude oil recovered from the OCS 

is of high importance to U.S refineries, especially along the Gulf Coast. In 2014, the Gulf of Mexico 

OCS produced 17 percent of domestic oil production and 5 percent of domestic natural gas 

production. For more details on national energy markets, refer to Chapter 4.3 of the 2017-2022 

OCS Oil and Gas Leasing: Draft Proposed Program (Draft Proposed Program) (USDOI, BOEM, 

2015a).

1.3 OCS OIL AND GAS PROGRAM PLANNING AND DECISION PROCESS

BOEM produces NEPA documents for each of the major stages of energy development 

planning. From the overarching Five-Year Program EIS, through each of the NEPA documents for 

the energy lease sales, and followed by more site-specific reviews for exploration, development and 

production, and platform removal plans (Figure 1-2).

Figure 1-2. OCS Oil and Gas Program Development Process.
Purpose of and Need for the Proposed Actions 1-7 

1.3.1 Prelease Process

BOEM has a two-stage Federal offshore prelease sale planning process:

(1) develop a Five-Year Program of proposed offshore lease sales for the OCS 

Program; and

(2) conduct an individual lease sale consultation and decision process for each 

lease sale on the approved Five-Year Program.

Due to the staged decisionmaking process in OCSLA, BOEM does a staged or tiered 

process in which NEPA documents are prepared that cover potential impacts associated with the 

various stages of the OCSLA process. This includes analyses at the Five-Year Program stage, 

proposed lease sale stage, exploration or development and production plan stage, and various 

permitting stages, including, but not limited to, drilling and decommissioning. At the lease sale 

stage, this is typically done through an EIS, which discusses postlease activities. However, at this 

stage, no activities beyond certain ancillary activities are actually authorized by the lease; therefore, 

there are few environmental impacts reasonably expected from the lease sale itself.

1.3.1.1 Five-Year Program of Proposed Offshore Lease Sales

As required by OCSLA, a new program—to cover the years 2017-2022—is under 

development. The Draft Proposed Program (USDOI, BOEM, 2015a) was the first proposal in the 

staged preparation process of the new Five-Year Program, which is a nationwide schedule of 

proposed lease sales. The Draft Proposed Program proposed a schedule of 14 potential lease sales 

in eight OCS planning areas: 10 lease sales in the three GOM planning areas; 1 lease sale each in 

the Chukchi Sea, Beaufort Sea, and Cook Inlet Planning Areas, offshore Alaska; and 1 lease sale in 

a portion of the combined Mid-Atlantic and South Atlantic Planning Areas. BOEM received hundreds 

of thousands of comments in response to the publication of the Draft Proposed Program and 

analyzed the comments as appropriate for the second proposal in the staged preparation process—

the Five-Year Program. The Five-Year Program was released for public comment in March 2016 

(USDOI, BOEM, 2016a).

The 2017-2022 OCS Oil and Gas Leasing Program: Programmatic Environmental Impact 

Statement (Five-Year Program EIS) (USDOI, BOEM, 2016b) includes an analysis of the potential 

environmental impacts of a proposed action, the GOM proposed lease sales in the Five-Year

Program. It also analyzes reasonable alternatives to the proposed lease sale schedule and the 

mitigating measures that may reduce or eliminate any potential impacts. On January, 29, 2015, 

BOEM released a Notice of Intent (NOI) to prepare the Programmatic EIS in conjunction with the 

release of the Draft Proposed Program. As a part of the NOI, BOEM solicited public input on the 

scope of the environmental analysis and on the alternatives and mitigating measures to be analyzed. 

BOEM received thousands of comments and analyzed and incorporated these as appropriate into 

the Programmatic EIS. The Draft Programmatic EIS was released for public comment in March 

2016 (Figure 1-3).
1-8 Gulf of Mexico Multisale EIS

Figure 1-3. Planning for the Five-Year Program.

1.3.1.2 Individual Lease Sale Consultation and Decision Process

The development of the Five-Year Program also triggers region-specific NEPA reviews for 

the proposed lease sales (refer to Figure 1-4). Region-specific reviews are conducted by Program 

Area (i.e., the Gulf of Mexico, Alaska, and Atlantic OCS Regions) prior to lease sale decisions for 

those areas that are included in the Program; however, the NEPA process could be halted if a 

Program Area is removed from the Five-Year Program. (No lease sales are currently proposed in 

the Pacific Region.) In order for the Gulf of Mexico OCS Region to complete this NEPA review prior 

to the first proposed lease sale in the fall of 2017, BOEM initiates scoping for the proposed lease 

sales in the GOM soon after the Five-Year Program EIS process is initiated. This allows for the 

NEPA analysis for the GOM proposed lease sales to be tiered from the Five-Year Program EIS 

analysis.

Figure 1-4. Planning for Regional OCS Oil and Gas Lease Sales.

Pursuant to the OCSLA staged leasing process, for each lease sale proposed in the FiveYear Program, BOEM makes individual decisions on whether and how to proceed with a proposed 

lease sale. Federal regulations allow for several related or similar proposals to be analyzed in one 
Purpose of and Need for the Proposed Actions 1-9 

EIS (40 CFR § 1502.4). Since each proposed lease sale and the projected activities related to such 

a lease sale are very similar, BOEM has decided to prepare a single EIS for the 10 proposed GOM 

lease sales in the Five-Year Program. However, as previously noted, OCSLA requires individual 

decisions to be made for each lease sale. Therefore, in order to make an informed decision on a 

single lease sale, the analyses contained in this Multisale EIS examine impacts from a single 

regionwide lease sale. A lease sale scenario, described in Chapter 3, includes all of the activities 

that could occur over a 50-year analysis period. The findings of these analyses can be applied 

individually to each of the subsequent proposed lease sales.

Unlike the 2012-2017 Five-Year Program in the GOM, BOEM does not plan to prepare a 

Supplemental EIS for every lease sale. However, given the long lead times necessary to complete 

an EIS or Supplemental EIS and the short timeframe between the proposed GOM lease sales in the 

Five-Year Program, BOEM plans to supplement this Multisale EIS on a regular basis to provide for 

more consistency and for planning purposes. Unless circumstances or information warrants an 

earlier Supplemental EIS, BOEM expects to issue a Supplemental EIS once a calendar year. An 

additional NEPA review (e.g., a Determination of NEPA Adequacy [DNA], an environmental 

assessment [EA] or, if determined necessary, a Supplemental EIS) will be conducted prior to the 

subsequent proposed GOM lease sales to address any relevant new information. Each subsequent 

supplemental review will tier from the previous NEPA documents in this series of reviews as 

illustrated in Figure 1-5. Informal and formal consultation with other Federal agencies, federally 

recognized Indian Tribes, the affected States, and all stakeholders may also be carried out as 

appropriate. Information requests will be issued soliciting input on subsequent GOM lease sales. 

This Multisale EIS will assist decisionmakers in making informed, future decisions regarding the 

approval of operations, as well as leasing.

Also, according to the Five-Year Program, any individual lease sale could still be scaled back 

during the prelease sale process to offer a smaller area should circumstances warrant. For 

example, an individual lease sale could offer an area that conforms more closely to the separate 

planning area model used in the 2012-2017 Five-Year Program. Therefore, the analyses in this 

Multisale EIS also include alternatives similar to past WPA, CPA, and EPA lease sale environmental 

reviews.

This Multisale EIS will be the NEPA document prepared for proposed Lease Sale 249. 

Subsequently, BOEM will prepare a supplemental NEPA document for each of the other proposed 

lease sales in the Five-Year Program. Respective NEPA documents will be completed before 

decisions are made on the subsequent lease sales. This Multisale EIS approach allows for 

subsequent NEPA analyses to focus on changes in the proposed lease sales and on new issues 

and information available since the publication of the previous NEPA document.
1-10 Gulf of Mexico Multisale EIS

Figure 1-5. Supplemental Approach Showing the Tiering Relationships for Proposed Gulf of Mexico 

Lease Sales.

1.3.2 Gulf of Mexico 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 in a safe and environmentally sound manner. BOEM’s 

regulations for oil, gas, and sulphur lease operations are specified in 30 CFR parts 550, 551, 554, 

and 556. The BSEE’s regulations for oil, gas, and sulphur operations are specified in 30 CFR parts 

250 and 254. Refer to Appendix A for descriptions of postlease activities, including the following: 

geological and geophysical (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 postlease 

activities; best available and safest technologies, including at production facilities; personnel training 

and education; structure removal and site clearance; marine protected species NTLs; and the Rigsto-Reefs program.

All plans for OCS oil- and gas-related activities (e.g., exploration and development plans) go 

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

regulations before any project-specific activities can begin on a lease. Existing mitigating measures 
Purpose of and Need for the Proposed Actions 1-11

are incorporated and documented in plans submitted to BOEM. These measures may be 

implemented through, among other things, lease stipulations and project-specific requirements or 

conditions of approval. Conditions of approval are based on BOEM’s and BSEE’s technical and 

environmental evaluations of the proposed operations. Conditions may be applied to any OCS plan, 

permit, right-of-use and easement, or pipeline right-of-way grant.

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 B (“Commonly Applied Mitigating Measures”) for more 

information on the mitigations that BOEM and BSEE often apply to permits and approvals. 

Operational compliance of the mitigating measures is enforced through BSEE’s onsite inspection 

program.

BOEM and BSEE issue Notices to Lessees and Operators (NTLs) to provide clarification, 

description, or interpretation of a regulation; guidelines on the implementation of a special lease 

stipulation or regional requirement; or convey administrative information. A detailed listing of the 

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

Region’s website at http://boem.gov/Regulations/Notices-Letters-and-Information-to-Lessees-andOperators.aspx or through the Region’s Public Information Office at 504-736-2519 or 1-800-200-

GULF.

1.4 THE DECISION TO BE MADE

BOEM will make an individual decision on whether and how to proceed with each proposed 

lease sale in the Five-Year Program. After completion of this Multisale EIS, BOEM will make a 

decision on proposed Lease Sale 249 (i.e., prepare a Record of Decision for Lease Sale 249 only). 

As discussed in Chapter 1.3.1, individual decisions will be made on each subsequent lease sale 

after completion of the appropriate supplemental NEPA documents.

1.5 REGULATORY FRAMEWORK

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

process (i.e., NEPA). These regulations are intended to encourage orderly, safe, and 

environmentally responsible development of oil, natural gas, alternative energy sources, and other 

mineral resources on the OCS. BOEM consults with numerous federally recognized Indian Tribes 

and Federal and State departments and agencies that have authority to govern and maintain ocean 

resources pursuant to other Federal laws. As illustrated in Figure 1-6, BOEM’s consultation 

partners for specific Federal regulations, several Federal regulations establish specific consultation 

and coordination processes with federally recognized Indian Tribes and Federal, State, and local 

agencies.
1-12 Gulf of Mexico Multisale EIS

Figure 1-6. BOEM’s Consultation Partners for Specific Federal Regulations.

Among these Federal entities are the U.S. Coast Guard (USCG), U.S. Environmental 

Protection Agency (USEPA), U.S. Army Corps of Engineers (COE), U.S. Fish and Wildlife Service 

(FWS), and the National Oceanic and Atmospheric Administration (NOAA) through the National 

Marine Fisheries Service (NMFS). In addition to coordinating with Federal Government entities, 

BOEM coordinates and consults with any State governor or local government executives that may 

be affected by a particular lease, easement, or right-of-way. Each state, with the exception of 

Alaska, has developed and implemented a federally approved coastal management program 

pursuant to the Coastal Zone Management Act (16 U.S.C. §§ 1451 et seq.). The boundaries of each 

State’s coastal zone are available at https://coast.noaa.gov/czm/media/StateCZBoundaries.pdf. A 

detailed description of major Federal laws and Executive Orders that are relevant to the OCS leasing 

process is provided in the OCS Regulatory Framework white paper, which can be found on BOEM’s 

website (Cameron and Matthews, 2016). Chapter 3 of BOEM’s OCS Regulatory Framework white 

paper identifies 43 major Federal laws and Executive Orders that are relevant to the OCS leasing 

process (Cameron and Matthews, 2016). BOEM also aims to establish government-to-government 

consultation with Tribal officials with regard to offshore oil- and gas-related activities in accordance 

with Executive Order 13175, “Consultation and Coordination with Indian Tribal Governments.” 

Federally recognized Indian Tribes are informed of proposed activities on the OCS and asked if they 

are interested in entering into consultation with BOEM to discuss the activities.
Purpose of and Need for the Proposed Actions 1-13

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 environmental and technical studies, 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. The information collected through these efforts is used in support of the BOEM 

NEPA documents that inform Agency decisions.

Environmental Studies Program

BOEM promotes energy independence, environmental protection, and economic 

development through responsible management of OCS resources based on the best available 

science. To support this work and inform bureau policy decisions, BOEM’s Environmental Studies 

Program develops, conducts, and oversees world-class scientific research specifically to inform 

policy decisions regarding development of OCS energy and mineral resources.

Through the Environmental Studies Program, BOEM is a leading contributor to the growing 

body of scientific knowledge about the marine and coastal environment. The Environmental Studies 

Program obtains information needed for NEPA assessment and the management of environmental 

and socioeconomic impacts on the human, marine, and coastal environments that may be affected 

by OCS oil and gas development. Research covers a broad range of disciplines, including physical 

oceanography, atmospheric sciences, biology, protected species, social sciences, economics, 

submerged cultural resources, and the environmental impacts of energy development. BOEM (and 

its predecessors) has funded more than $1 billion in research since the studies program was 

established in 1973 in accordance with Section 20 of the OCSLA. Technical summaries of more 

than 1,200 BOEM-sponsored environmental research projects and more than 3,400 research reports 

are publicly available online through the Environmental Studies Program Information System 

(ESPIS). For the latest information on BOEM’s ongoing environmental studies work, go to 

http://www.boem.gov/studies. In the Gulf of Mexico OCS Region, over 350 studies for approximately 

$250 million have been completed and more than 900 reports and scientific papers have been 

produced. A complete list of all ongoing Gulf of Mexico OCS Region studies is available on the 

BOEM website. Each listing not only describes the research being conducted but also shows the 

institution performing the work, the cost of the effort, timeframe, and any associated publications, 

presentations, or affiliated websites.

BOEM incorporates findings from the studies program into its environmental reviews and 

NEPA documents, which are used to avoid, mitigate, or monitor the impact of energy and mineral 

resource development on the OCS. The BOEM’s Gulf of Mexico OCS Region analysts use the ESP 

studies to prepare this document. While not all of the Gulf of Mexico OCS Region’s studies are 

specifically referenced in this Multisale EIS, analysts used those that are relevant. Decisionmakers 

also use the information in ESP studies in managing and regulating exploration, development, and 
1-14 Gulf of Mexico Multisale EIS

production activities on the OCS. This integrated approach of incorporating applied science to 

inform decisionmakers is illustrated in Figure 1-7. 

Figure 1-7. BOEM’s Integrated Approach for Incorporating Applied Science into 

Decisionmaking.

Technology Assessment Program

The BSEE’s Technology Assessment Program supports research associated with 

operational safety and pollution prevention. The Technology Assessment Program is comprised of 

two functional research activities: (1) operational safety and engineering research (topics such as 

air quality, decommissioning, and mooring and anchoring); and (2) other research (topics such as 

renewable energy and alternate use; Hurricanes Andrew, Ivan, Katrina, Rita, and Lili; and 

international activities). The Technology Assessment Program has four primary objectives:

• Technical Support—Providing engineering support in evaluating industry 

operational proposals and related technical issues and in ensuring that these 
Purpose of and Need for the Proposed Actions 1-15

proposals comply with applicable regulations, rules, and operational guidelines 

and standards.

• Technology Assessment—Investigating and assessing industry applications of 

technological innovations and promoting the use of the best available and safest 

technologies in Bureau regulations, rules, and operational guidelines.

• Research Catalyst—Promoting leadership in the fields of operational safety and 

pollution prevention in offshore energy extraction activities.

• International Regulations—Providing international cooperation for research and 

development initiatives to enhance the safety of offshore energy extraction 

activities and the development of appropriate regulatory program elements 

worldwide.

Interagency Agreements

Memoranda of Understanding under NEPA

The Council on Environmental Quality’s (CEQ) implementing regulations (40 CFR § 

1500.5(b)) encourages agency cooperation early in the NEPA process. A Federal agency can be a 

lead, joint lead, or cooperating agency. A lead agency manages the NEPA process and is 

responsible for the preparation of an EIS; a joint lead agency shares these responsibilities; and a 

cooperating agency that has jurisdiction by law and has special expertise with respect to any 

environmental issue shall participate in the NEPA process upon the request of the lead agency.

When an agency becomes a cooperating agency, the cooperating and lead agencies usually 

enter into a Memorandum of Understanding (MOU), previously called a Cooperating Agency 

Agreement. The MOU details the responsibilities of each participating agency. BOEM, as lead 

agency, has previously requested other Federal agencies to become cooperating agencies while 

other agencies have requested BOEM to become a cooperating agency (e.g., the Ocean Express 

Pipeline project). Some projects, such as major gas pipelines across Federal waters and projects 

under the Deepwater Port Act of 1974, can require cooperative efforts by multiple Federal and State 

agencies.

The NOI for this Multisale EIS included an invitation to other Federal agencies and State, 

Tribal, and local governments to consider becoming cooperating agencies in the preparation of this 

EIS. Consultation and coordination activities for this Multisale EIS are described in Chapter 5. In a 

letter dated September 8, 2015, the U.S. Environmental Protection Agency’s (USEPA) Regions 4 

and 6 requested cooperating agency status for the 2017-2022 Multisale EIS. On December 16, 

2015, a Memorandum of Agreement between BOEM’s Gulf of Mexico OCS Region and USEPA 

Regions 4 and 6 was initiated; this Memorandum of Agreement defines the roles and responsibilities 

for each agency (Appendix C).
1-16 Gulf of Mexico Multisale EIS

Memorandum of Understanding and Memoranda of Agreement between BSEE and USCG

Since BSEE and USCG have closely related jurisdiction over different aspects of safety and 

operations on the OCS, the agencies have established a formal MOU that delineates lead 

responsibilities for managing OCS activities in accordance with OCSLA, as amended, and Oil 

Pollution Act of 1990. The latest MOU, dated November 27, 2012, supersedes the September 2004, 

December 1998, and August 1989 versions of the interagency agreement. The MOU is designed to 

minimize duplication and promote consistent regulation of facilities under the jurisdiction of both 

agencies.

Generally, the MOU identifies BSEE as the lead agency for matters concerning the 

equipment and operations directly involved in the production of oil and gas. These include, among 

others, design and operation of risers, permanent mooring foundations of the facility, drilling and well 

production and services, inspection and testing of all drilling-related equipment, and platform 

decommissioning. Issues regarding certain aspects of safe operation of the facility, its systems, and 

equipment generally fall under the jurisdiction of the USCG. These include, among others, design of 

vessels, their sea-keeping characteristics, propulsion and dynamic positioning systems, supply and 

lightering procedures and equipment, utility systems, safety equipment and procedures, and 

pollution prevention and response procedures.

Memorandum of Agreement between BOEM and BSEE – Environmental and NEPA

The BOEM/BSEE Memorandum of Agreement establishes the working relationship between 

BOEM and BSEE for environmental review and enforcement for activities on the OCS. It is intended 

to minimize duplication of efforts, promote consistency in procedures and regulations, and resolve 

disputes. Under this Memorandum of Agreement, BSEE will serve as a cooperating agency on the 

BOEM’s NEPA documents and may adopt NEPA analyses prepared by BOEM.

1.7 OTHER PERTINENT ENVIRONMENTAL REVIEWS OR DOCUMENTATION

BOEM is aware of other environmental reviews and studies relevant to the resources under 

consideration in this Multisale EIS. Notices of Intent were published in the Federal Register for the 

following reviews:

• BOEM’s Gulf of Mexico Geological and Geophysical Activities Programmatic EIS. 

BOEM, with the National Oceanic and Atmospheric Administration’s NMFS and 

BSEE as cooperating agencies, is preparing a Programmatic EIS to evaluate the 

potential environmental impacts of multiple G&G activities within Federal waters 

of the Gulf of Mexico’s OCS and adjacent State waters. BOEM and the NMFS 

intend for that Programmatic EIS to provide the necessary documentation and 

analyses to support informed decisions regarding future OCSLA permit and 

Marine Mammal Protection Act (MMPA) authorization actions related to G&G 

activities on the OCS. In addition, the preparation of this Programmatic EIS will 

help to ensure compliance with other applicable laws and statutes such as the 
Purpose of and Need for the Proposed Actions 1-17

Endangered Species Act (ESA), Magnuson-Stevens Fishery Conservation and 

Management Act, Coastal Zone Management Act (CZMA), and the National 

Historic Preservation Act (NHPA). The G&G Programmatic EIS establishes a 

framework for subsequent NEPA analyses for site-specific actions while 

identifying and analyzing appropriate mitigating measures to be used during 

future G&G activities on the OCS in support of the oil and gas, renewable 

energy, and marine mineral resource programs. The impacts of future sitespecific actions will be addressed in subsequent NEPA evaluations, per the 

Council on Environmental Quality’s regulations (40 CFR § 1502.20), by tiering 

from this programmatic evaluation. Public scoping for the Programmatic EIS was 

held from May 10-July 9, 2013, and the Draft Programmatic EIS is currently 

being developed.

• NOAA’s Flower Garden Banks National Marine Sanctuary Expansion EIS. In 

February 2015, NOAA's Office of National Marine Sanctuaries announced that it 

will prepare a Draft EIS to consider possible expansion of the Flower Garden 

Banks National Marine Sanctuary. When the Flower Garden Banks National 

Marine Sanctuary was designated in 1992, the boundaries were established 

based on best available information regarding biologically sensitive habitats. 

Subsequent exploration in the northwestern Gulf of Mexico has identified other 

reefs, banks, and associated features that may be ecologically linked to the 

Flower Garden Banks National Marine Sanctuary. Although many of these areas 

have some level of protection through other designations, inclusion in the 

sanctuary would provide a comprehensive management framework to fill in the 

existing regulatory gaps and provide necessary protection to these critical 

habitats. BOEM, among other agencies, is a Cooperating Agency in the 

preparation of this Draft EIS.

• NOAA’s Natural Resource Damage Assessment Draft EIS. In February 2016, 

the Federal and State natural resource trustee agencies (Trustees) issued a 

Final Programmatic Damage Assessment and Restoration Plan and Final 

Programmatic Environmental Impact Statement (PDARP/PEIS) for public review. 

The PDARP/PEIS considers programmatic alternatives to restore natural 

resources, ecological services, and recreational use services injured or lost as a 

result of the Deepwater Horizon oil spill. The Deepwater Horizon oil spill’s 

natural resource Trustees have developed restoration alternatives, comprised of 

various restoration types, to address injuries to natural resources and resource 

services resulting from the Deepwater Horizon oil spill. Criteria and evaluation 

standards under the Oil Pollution Act of 1990’s natural resource damage 

assessment regulations guided the Trustees’ consideration of programmatic 

restoration alternatives. The PDARP/PEIS also evaluates the environmental 

consequences of the restoration alternatives under NEPA.
1-18 Gulf of Mexico Multisale EIS

Supporting technical information in previous NEPA reviews have been developed as 

standalone technical reports and are summarized and incorporated by reference as appropriate. 

These include the OCS regulatory framework and improvements since the Deepwater Horizon

explosion, oil spill, and response; the catastrophic spill event analysis; and the essential fish habitat 

assessment. Subsequent updates to this information have been minimal and, therefore, BOEM has 

prepared separate technical reports, which will be updated as needed. This approach would be 

conducive to reducing the size of this Multisale EIS and future NEPA documents.

• OCS Regulatory Framework White Paper. Federal laws mandate the OCS 

leasing program (i.e., the OCSLA) and the environmental review process (i.e., 

the NEPA). In implementing its responsibilities under the OCSLA, BOEM and 

BSEE must consult with numerous Federal departments and agencies that have 

authority to govern and maintain ocean resources pursuant to other Federal 

laws. Among these Federal entities are the USCG, USEPA, COE, FWS, and the 

NOAA through the NMFS. Several Federal regulations establish specific 

consultation and coordination processes with Federal, State, and local agencies 

(i.e., the Coastal Zone Management Act of 1972 [CZMA], the Endangered 

Species Act of 1973 [ESA], the Magnuson-Stevens Fishery Conservation and 

Management Act, and the Marine Mammal Protection Act [MMPA]). These 

regulations have been discussed in past NEPA documents for oil and natural gas 

lease sales, such as Gulf of Mexico OCS Oil and Gas Lease Sales: 2007-2012; 

Western Planning Area Lease Sales 204, 207, 210, 215, and 218; Central 

Planning Area Lease Sales 205, 206, 208, 213, 216, and 222, Final 

Environmental Impact Statement (2007-2012 WPA/CPA Multisale EIS) (USDOI, 

MMS, 2007a). This report is available on BOEM’s website (Cameron and 

Matthews, 2016).

• Catastrophic Spill Event Analysis White Paper. The August 16, 2010, CEQ 

report, prepared following the Deepwater Horizon explosion, oil spill, and 

response in the GOM, recommended that BOEM, formerly the Minerals 

Management Service (MMS) and Bureau of Ocean Energy Management, 

Regulation and Enforcement (BOEMRE), should “[e]nsure that NEPA [National 

Environmental Policy Act] 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). BOEM prepared a 

“Catastrophic Spill Event Analysis,” which was included as Appendix B in the 

2007-2012 WPA/CPA Multisale EIS. This analysis has been reviewed and 

updated, as appropriate, during each Supplemental EIS for the remaining GOM 

proposed lease sales through 2017. These subsequent updates have been 

minimal and, therefore, BOEM has prepared a separate technical report, which 

will be updated as needed. This evaluation is a robust analysis of the impacts 

from low-probability catastrophic spills and will be made available to all 
Purpose of and Need for the Proposed Actions 1-19

applicable decisionmakers including, but not limited to, the Secretary of the 

Department of the Interior for the 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. This report is also available on BOEM’s website 

(USDOI, BOEM, 2016c).

• Essential Fish Habitat Assessment White Paper. The 2017-2022 Programmatic 

EFH Assessment for the Gulf of Mexico (“EFH Assessment”) is a stand-alone 

analysis that addresses BOEM’s obligation under Section 305(b) of the 

Magnuson-Stevens Fishery Conservation and Management Act (16 U.S.C. § 

1855(b)) to consult with the U.S. Department of Commerce regarding actions that 

may adversely affect essential fish habitat. The EFH Assessment also informs 

many of the analyses documented in this Multisale EIS. The Federal actions 

addressed in the EFH Assessment are proposed Gulf of Mexico Lease Sales 

249-254, 256, 257, 259, and 261 and related activities, such as G&G activities 

and decommissioning operations. Lease sales would offer for lease some or all 

unleased blocks in the WPA, CPA, and EPA proposed lease sale areas for oil 

and gas exploration and recovery operations. A proposed action would provide 

for the issuance of permits to conduct G&G survey activities between the 

coastline and the seaward extent of the Exclusive Economic Zone of the GOM. 

Decommissioning operations encompass many component activities: 

(1) equipment and vessel mobilization and target preparation; (2) underwater 

structural-member severance (nonexplosive and explosive methods); (3) postseverance salvage; and (4) final site-clearance verification. These types of 

activities all have the potential to impact fish and EFH. The EFH Assessment 

serves as the initiation of a Programmatic Consultation by BOEM’s Gulf of 

Mexico OCS Region with the U.S. Department of Commerce on OCS oil- and 

gas-related activities for 2017-2022. Based on the most recent and best 

available information, BOEM will also continue to evaluate and assess risks to 

managed species and identified EFH in upcoming environmental compliance 

documentation under NEPA and other statutes. Information relevant to EFHs is 

incorporated and analyzed in this Multisale EIS in Chapter 4.2 (Water Quality), 

Chapter 4.3 (Coastal Habitats), Chapter 4.4 (Deepwater Benthic Communities),

Chapter 4.5 (Sargassum and Associated Communities), and Chapter 4.6 (Live 

Bottom Habitats) (USDOI, BOEM, 2016d).

1.8 FORMAT AND ORGANIZATION OF THE MULTISALE EIS 

In an effort to thoroughly explain all the environmental consideration and mitigations that are 

involved in BOEM’s assessment of the potential environmental consequences of OCS oil- and gasrelated activities, BOEM recognizes that past NEPA reviews have become encyclopedic in nature. 

To more closely align with CEQ’s guidance regarding EIS format, a major goal in preparing this 

Multisale EIS includes increasing the readability of the document for decisionmakers and the public, 
1-20 Gulf of Mexico Multisale EIS

and shortening the document by providing relevant and appropriate information needed to assess 

the effects of the proposed actions and alternatives. A major focus for preparing this Multisale EIS 

has been on clear and concise writing, using graphics to emphasize major concepts where 

appropriate, and placing more detailed and technical supporting information in the appendices and 

incorporating it by reference. The remaining chapters in this Multisale EIS are described below.

• Chapter 2 describes the potential lease sale options and the alternatives, 

including the proposed action, being analyzed in this Multisale EIS; discusses the 

potential mitigating measures (pre- and postlease), including the proposed 

stipulations, and the issues considered and not considered in the analysis; and 

discusses the deferred alternatives and provides a broad comparison of impacts 

by alternative.

• Chapter 3 describes all the potentially occurring actions associated with a single 

lease for the Five-Year Program and the cumulative activities that provide a 

framework for detailed analyses of the potential impacts analyzed in Chapter 4. 

Exploration and development scenarios describe the infrastructure and activities 

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

in the GOM. It is a hypothetical framework of assumptions based on estimated 

amounts, timing, and general locations of OCS exploration, development, and 

production activities and facilities, both offshore and onshore. It also includes a 

set of ranges for resource estimates, projected exploration and development 

activities, and impact-producing factors.

• Chapter 4 describes the affected environment and the potential impacts of a 

single lease sale and each alternative by resource. Analysis of the alternatives 

includes routine activities, accidental events, cumulative impact analysis, 

incomplete or unavailable information, and conclusions for each resource.

• Chapter 5 describes the consultation and coordination efforts used in preparing 

this Multisale EIS. This includes a description of the scoping process, activities, 

and results; cooperating agencies; distribution of the EIS; consultations with 

Federal and State agencies under the Coastal Zone Management Act, 

Endangered Species Act, the Magnuson-Stevens Fishery Conservation and 

Management Act, and the National Historic Preservation Act; and government-togovernment consultation and coordination.

• Chapter 6 includes all the citations referred to throughout this Multisale EIS.

• Chapter 7 is a list of all the preparers of this Multisale EIS.

• Chapter 8 is a glossary of terms.

• Finally, to improve the readability of this Multisale EIS, more detailed supporting 

information has been placed in the Appendices. 
CHAPTER 2 

ALTERNATIVES INCLUDING THE PROPOSED ACTIONS

Alternatives Including the Proposed Actions 2-3 

What’s In This Chapter

• This Multisale EIS will be the NEPA document used to support a decision on proposed 

Lease Sale 249.

• The analyses in the Multisale EIS are also relevant to proposed Lease Sales 250-254, 256, 

257, 259, and 261.

• Alternative A: A single proposed lease sale offering all available unleased blocks within 

the WPA, CPA, and EPA portions of the proposed lease sale area with exceptions as 

outlined in Chapter 2.2.2.

• Alternative B: A single proposed lease sale offering all available unleased blocks within 

the CPA and EPA but not within the WPA portion of the proposed lease sale area with 

exceptions.

• Alternative C: A single proposed lease sale offering all available unleased blocks within 

the WPA but not within the CPA/EPA portions of the proposed lease sale area with one 

exception.

• Alternative D: Alternative A, B, or C with the option to exclude any available unleased 

blocks subject to the Topographic Features Stipulation, Live Bottom (Pinnacle Trend) 

Stipulation, and/or Blocks South of Baldwin County, Alabama Stipulation.

• Alternative E: Cancellation of a single proposed lease sale.

• Alternatives not analyzed include the following:

− follow the 2012-2017 Five-Year Program leasing schedule, including separate 

lease sales for the EPA;

− add additional buffer zones to further protect sensitive environments, species, 

or the view from shores;

− exclude the WPA and CPA;

− add more measures to reduce the potential impacts to sperm whale high-use 

areas; and

− delay the proposed lease sales until the state of recovery of the GOM following 

the Deepwater Horizon explosion, oil spill, and response is known.

• The issues that most impact the decision to lease are reviewed in this Multisale EIS, 

including impacts to air and water quality, biological resources, recreation, land use, 

economics, and environmental justice.

• A comparison of alternatives and impact summaries is presented.

2 ALTERNATIVES INCLUDING THE PROPOSED ACTIONS

2.1 MULTISALE NEPA ANALYSIS

As authorized under 40 CFR § 1502.4, one EIS is allowed to analyze related or similar 

proposals. This Multisale EIS addresses 10 proposed regionwide oil and gas lease sales 

encompassing all three planning areas in the U.S. portion of the Gulf of Mexico OCS (Figure 1-1), 

as scheduled in the Five-Year Program (USDOI, BOEM, 2016a). However, as previously noted in 

Chapter 1.3.1.2, the OCSLA requires individual decisions to be made for each lease sale. 

Therefore, in order to make an informed decision on a single proposed lease sale, the analyses 

contained in this Multisale EIS examine impacts from a single regionwide proposed lease sale (i.e. 

proposed Lease Sale 249).

For analysis purposes, a proposed action is presented as a set of ranges for resource 

estimates, projected exploration and development activities, and impact-producing factors for the 
2-4 Gulf of Mexico Multisale EIS

Agencies are encouraged to tier 

their environmental impact 

statements to eliminate repetitive 

discussions of the same issues 

and to focus on the actual issues 

ripe for decision at each level of 

environmental review. 

Agencies are encouraged to tier 

their environmental impact 

statements to eliminate repetitive 

discussions of the same issues 

and to focus on the actual issues 

ripe for decision at each level of 

environmental review. 

proposed lease sale area. Each of the proposed lease sales is expected to be within the scenario 

ranges for the proposed lease sale area analyzed in this Multisale EIS; therefore, a proposed action 

is also representative of proposed Lease Sales 249-254, 256, 257, 259, and 261. Each proposed 

action includes existing regulations and lease stipulations. This EIS will be the only NEPA document 

prepared for proposed Lease Sale 249. An additional NEPA review (a Determination of NEPA 

Adequacy, an EA or, if determined necessary, a Supplemental EIS) will be conducted prior to each 

of the remaining proposed lease sales to address any relevant new information. Informal and formal 

consultations with other Federal agencies, the affected States, federally recognized Indian Tribes, 

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

analyses in this Multisale EIS are still valid. Specifically, information requests such as NOIs and 

request for public comment will be issued soliciting input on subsequent proposed lease sales (refer 

to Chapter 1.3.1.2).

The supplemental approach for regional lease sales 

is intended to focus the NEPA/EIS process on updating 

subsequent lease sale NEPA reviews to address any 

relevant significant new information and/or issues since 

publication of the previous lease sale NEPA document from 

which it tiers (Figure 1-5) This tiering approach process 

also lessens duplication and saves resources. The scoping 

process for this document is described in Chapter 5. As 

mandated by NEPA, this Multisale EIS analyzes the 

potential impacts of the proposed actions on the marine, coastal, and human environment.

Any subsequent NEPA reviews will tier from this Multisale EIS and will summarize and 

incorporate the material by reference. Because any subsequent reviews will be prepared for a 

proposed action that “is, or is closely similar to, one which normally requires the preparation of an 

EIS” (40 CFR § 1501.4(e)(2)), the review will be made publicly available.

If a Supplemental EIS is necessary (40 CFR § 1502.9), it will also tier from this Multisale EIS 

and will summarize and incorporate the material by reference. The analysis will focus on addressing 

the new issue(s) and/or concern(s). The Supplemental EIS will include a discussion of the purpose 

of the Supplemental EIS, a description of the proposed action(s) and alternatives, a comparison of 

the proposed alternatives, a description of the affected environment, potentially affected resources, 

an analysis of new impacts, and new information not addressed in this Multisale EIS. The 

Supplemental EIS will also include an updated discussion of associated BOEM coordination and 

consultations. As discussed further in Chapter 1.7, an analysis of the impacts of low-probability 

catastrophic spills has been prepared as a BOEM white paper and is incorporated by reference 

(Catastrophic Spill Event Analysis white paper; USDOI, BOEM, 2016c).
Alternatives Including the Proposed Actions 2-5 

2.2 LEASE SALE OPTIONS, ALTERNATIVES, MITIGATING MEASURES, AND ISSUES

BOEM is evaluating a preferred option and alternative options for a schedule of proposed 

lease sales in the Gulf of Mexico OCS Region under the Five-Year Program, which takes into 

account the mature and active nature of this region. The preferred option (Option 1 in the Five-Year 

Program) proposes a new approach to lease sales in the GOM by proposing two annual lease sales 

across the GOM that would include all available unleased blocks not subject to Congressional 

moratoria. Option 2 in the Five-Year Program follows the recent historical trend of BOEM holding 

separate annual lease sales in the WPA and CPA and periodic lease sales in the area of the EPA 

not subject to moratoria. Option 2 would be similar to the approach used in the 2012-2017 

Five-Year Program. Below is a description of the lease sale options considered in this Multisale EIS 

followed by a range of alternatives to the proposed action that can be considered for selection under 

either lease sale option for any given lease sale throughout the 2017-2022 Five-Year Program. 

2.2.1 Lease Sale Options in the Five-Year Program

Five-Year Program Option 1 (Preferred 

Alternative Identified in the Five-Year Program): A total 

of 10 proposed lease sales during the Five-Year 

Program, with 1 lease sale in 2017; 2 lease sales each 

year in 2018, 2019, 2020, and 2021; and 1 lease sale 

in 2022 offering all available unleased blocks not 

subject to Congressional moratorium in the combined 

WPA, CPA, and EPA in each proposed lease sale. 

This has been identified as BOEM’s preferred option; 

however, this does not mean that another option may 

not be selected in the Record of Decision.

The regionwide lease sale approach would provide greater flexibility for industry, including 

responding to changing conditions (including Mexico’s new plan to offer offshore licenses every 

September starting in 2015); would better balance workload within BOEM; and would allow more 

frequent opportunities to bid on rejected, relinquished, or expired blocks. Also, any individual lease 

sale could still be scaled back during the prelease sale process to conform more closely to the 

separate planning area model used in the 2012-2017 Five-Year Program, if conditions warranted 

such an approach. In addition, Option 1 could facilitate better planning to explore pools that may 

straddle the U.S.-Mexico boundary. Other possible advantages of implementing this option would 

be the potential to prepare one EIS and combined Endangered Species Act (ESA) consultations 

(e.g., 1 biological opinion), which could result in cost savings and a shorter timeline for completion of 

the process. More frequent lease sales may expedite and increase the present value of leasing and 

tax revenues. More frequent lease sales, however, could reduce the time available for companies to 

update their information and develop improved value estimates for the remaining available unleased 

blocks. 

Option 1: 2017-2022 Proposed

Gulf of Mexico Lease Sale Schedule

Lease Sale Number Year

249 2017

250 and 251 2018

252 and 253 2019

254 and 256 2020

257 and 259 2021

261 2022
2-6 Gulf of Mexico Multisale EIS

Five-Year Program Option 2: Five 

annual lease sales beginning in 2017 in the 

WPA offering all available unleased blocks and 

five annual lease sales beginning in 2018 in the 

combined CPA and EPA offering all available 

unleased blocks not subject to Congressional 

moratorium pursuant to the Gulf of Mexico 

Energy Security Act of 2006 (GOMESA). This 

approach would be very similar to the 2012-2017 

Five-Year Program and proposed actions in the 2012-2017 WPA/CPA Multisale EIS (USDOI, 

BOEM, 2012), differing by combining the CPA and EPA for five of the proposed lease sales rather 

than holding separate, less frequent, lease sales for the EPA. This would make the available 

unleased blocks within the EPA portion of the proposed lease sale area available more frequently 

than in the 2012-2017 Five-Year Program. Potential advantages of implementing this option would 

be that stakeholders are accustom to this frequency of sales, companies assessing and evaluating 

prospects would have additional time to analyze and prepare bidding and exploration strategies, and 

BOEM would have more time to prepare and analyze new information. However, this option would 

offer less frequent opportunities to bid on rejected, relinquished, or expired blocks and could reduce 

the flexibility for industry to explore pools that may straddle the U.S.-Mexico boundary.

2.2.2 Description of the Alternatives for This Multisale EIS

The discussions below outline the alternatives that are considered for this environmental 

analysis. These suggested alternatives have been derived from both the historical comments 

submitted to BOEM and its predecessors and the EIS-specific scoping performed for this analysis.

2.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Alternative A would allow for a proposed regionwide lease sale encompassing all three 

planning areas within the U.S. portion of the Gulf of Mexico OCS for any given lease sale in the FiveYear Program. This is BOEM’s preferred alternative. This alternative would offer for lease all 

available unleased blocks within the WPA, CPA, and EPA portions of the proposed lease sale area 

for oil and gas operations (Figure 2-1), with the following exceptions:

(1) whole and portions of blocks deferred by the Gulf of Mexico Energy Security Act 

of 2006 (discussed in the OCS Regulatory Framework white paper [Cameron 

and Matthews, 2016]); 

(2) blocks that are adjacent to or beyond the United States’ Exclusive Economic 

Zone in the area known as the northern portion of the Eastern Gap; and

(3) 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 

Multisale EIS).

Option 2: 2017-2022 Proposed

Gulf of Mexico Lease Sale Schedule

Lease Sale Area Year Lease Sale Area Year

WPA 2017 CPA/EPA 2018

WPA 2018 CPA/EPA 2019

WPA 2019 CPA/EPA 2020

WPA 2020 CPA/EPA 2021

WPA 2021 CPA/EPA 2022
Alternatives Including the Proposed Actions 2-7 

Figure 2-1. Proposed Regionwide Lease Sale Area, Encompassing the Available Unleased Blocks 

within All Three Planning Areas (a total of approximately 92.2 million acres with 

approximately 72.5 million acres available for lease as of March 2016).

The WPA 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 referred to as the Exclusive Economic Zone) in water depths up to 

approximately 3,346 m (m) (10,978 feet [ft]). The proposed WPA lease sale area encompasses 

about 28.58 million ac. As of March 2016, approximately 23.6 million ac of the proposed WPA lease 

sale area are currently unleased.

The CPA begins 3 nmi (3.5 mi; 5.6 km) offshore Louisiana, Mississippi, and Alabama, and 

extends seaward to the limits of the United States’ jurisdiction over the continental shelf (often 

referred to as the Exclusive Economic Zone) in water depths up to approximately 3,346 m 

(10,978 ft). The area is south of eastern Alabama and western Florida; the nearest point of land is 

125 mi (201 km) northwest in Louisiana. The proposed CPA lease sale area encompasses about 

63 million ac of the total CPA area of 66.45 million ac. As of March 2016, approximately 

48.3 million ac of the proposed CPA lease sale area are currently unleased.

The proposed EPA lease sale area covers approximately 657,905 ac and includes those 

blocks previously included in the EPA Lease Sales 225 and 226 areas, which is bordered by the 
2-8 Gulf of Mexico Multisale EIS

CPA boundary on the west and the Military Mission Line (86o41' W. longitude) on the east. The area 

is south of eastern Alabama and western Florida; the nearest point of land is 125 mi (201 km) 

northwest in Louisiana. As of March 2016, approximately 595,475 ac of the proposed EPA lease

sale area are currently unleased.

A regionwide lease sale would offer approximately 92.2 million ac, with approximately 

72.5 million ac available for lease as of March 2016. Leasing information related to all three 

planning areas is updated monthly and can be found on BOEM’s website at 

http://www.boem.gov/Gulf-of-Mexico-Region-Lease-Map/. 

In general, a regionwide lease sale, which would include all available unleased blocks in all 

three planning areas, would represent 1.2-3.8 percent of the total OCS Program production in the 

GOM based on barrels of oil equivalent resource estimates. The estimated amounts of resources 

projected to be leased, discovered, developed, and produced as a result of a typical proposed 

regionwide lease sale are 0.211-1.118 billion barrels of oil (BBO) and 0.547-4.424 trillion cubic feet 

(Tcf) of gas (refer to Table 3-1).

The analyses of impacts summarized below in Chapter 2.3 and described in detail in 

Chapter 4 for each resource are based on the development scenario, which is a set of assumptions 

and estimates on the amounts, locations, and timing for OCS exploration, development, and 

production operations and facilities, both offshore and onshore. A detailed discussion of the 

development scenario and major related impact-producing factors is included in Chapter 3. A 

proposed lease sale includes proposed lease stipulations designed to reduce environmental risks; 

these stipulations are discussed in Chapter 2.2.4.1. 

2.2.2.2 Alternative B—Regionwide OCS Lease Sale Excluding Available Unleased Blocks in 

the WPA Portion of the Proposed Lease Sale Area

Alternative B would allow for a proposed lease sale encompassing the CPA and EPA within 

the U.S. portion of the Gulf of Mexico OCS (Figure 2-2). Available blocks within the WPA would not

be considered under this alternative. This alternative would offer for lease all available unleased 

blocks within the CPA and EPA portions of the proposed lease sale area as those planning area 

portions are described in Alternative A for oil and gas operations, with the following exceptions:

(1) whole and portions of blocks deferred by the Gulf of Mexico Energy Security Act 

of 2006 (discussed in the OCS Regulatory Framework white paper [Cameron 

and Matthews, 2016]); and

(2) blocks that are adjacent to or beyond the United States’ Exclusive Economic 

Zone in the area known as the northern portion of the Eastern Gap.
Alternatives Including the Proposed Actions 2-9 

Figure 2-2. Proposed Lease Sale Area for Alternative B, Excluding the Available Unleased Blocks in 

the WPA (a total of approximately 66.45 million ac with approximately 48.3 million ac 

available for lease as of March 2016).

In general, a lease sale that would include all available unleased blocks in the CPA and EPA 

would represent approximately 2.0-3.6 percent of the total OCS Program production in the GOM 

based on barrels of oil equivalent resource estimates. The estimated amounts of resources 

projected to be leased, discovered, developed, and produced as a result of a proposed lease sale 

under Alternative B are 0.185-0.970 BBO and 0.44-3.672 Tcf of gas (refer to Table 3-1).

The analyses of impacts summarized below in Chapter 2.3 and described in detail in 

Chapters 4.1-4.14 for each resource are based on the development scenario, which is a set of 

assumptions and estimates on the amounts, locations, and timing for OCS exploration, 

development, and production operations and facilities, both offshore and onshore. A detailed 

discussion of the development scenario and major related impact-producing factors is included in 

Chapter 3. A proposed lease sale includes proposed lease stipulations designed to reduce 

environmental risks; these stipulations are discussed in Chapter 2.2.4.1.
2-10 Gulf of Mexico Multisale EIS

2.2.2.3 Alternative C—Regionwide OCS Lease Sale Excluding Available Unleased Blocks in 

the CPA/EPA Portions of the Proposed Lease Sale Area

Alternative C would allow for a proposed lease sale encompassing the WPA within the U.S. 

portion of the Gulf of Mexico OCS (Figure 2-3). Available blocks within the CPA and EPA would not

be considered under this alternative. This alternative would offer for lease all available unleased 

blocks within the WPA portion of the proposed lease sale area for oil and gas operations, 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 

Multisale EIS).

Figure 2-3. Proposed Lease Sale Area for Alternative C, Excluding the Available Unleased Blocks in 

the CPA and EPA (a total of approximately 28.58 million ac with approximately 23.6 million 

ac available for lease as of March 2016).

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

approximately 28.58 million ac as that planning area is described as a subset of Alternative A. In 

general, a lease sale that would include all available unleased blocks in the WPA as Alternative B 

would represent approximately 0.35-0.6 percent of the total OCS Program production in the GOM 

based on barrels of oil equivalent resource estimates. The estimated amounts of resources 
Alternatives Including the Proposed Actions 2-11

projected to be leased, discovered, developed, and produced as a result of a proposed lease sale 

offering only WPA available blocks are 0.026-0.148 BBO and 0.106-0.752 Tcf of gas (refer to 

Table 3-1).

The analyses of impacts summarized below in Chapter 2.3 and described in detail in 

Chapter 4 for each resource are based on the development scenario, which is a set of assumptions 

and estimates on the amounts, locations, and timing for OCS exploration, development, and 

production operations and facilities, both offshore and onshore. A detailed discussion of the 

development scenario and major related impact-producing factors is included in Chapter 3. A 

proposed lease sale includes proposed lease stipulations designed to reduce environmental risks; 

these stipulations are discussed in Chapter 2.2.4.1. 

2.2.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D could be combined with any of the Action alternatives above (i.e., Alternatives 

A, B, or C) and would allow the flexibility to offer leases under any alternative with additional 

exclusions. Under Alternative D, the decisionmaker could exclude from leasing any available 

unleased blocks subject to any one and/or a combination of the following stipulations:

− Topographic Features Stipulation;

− Live Bottom (Pinnacle Trend) Stipulation; and 

− Blocks South of Baldwin County, Alabama, Stipulation (not applicable to 

Alternative C).

This alternative considered blocks subject to these stipulations because these areas have 

been emphasized in scoping, can be geographically defined, and adequate information exists 

regarding their ecological importance and sensitivity to OCS oil- and gas-related activities.

A total of 207 blocks within the CPA and 160 blocks in the WPA are affected by the 

Topographic Features Stipulation (Figure 2-4). There are currently no identified topographic 

features protected under this stipulation in the EPA. The Live Bottom Stipulation covers the pinnacle

trend area of the CPA, affecting a total of 74 blocks (Figure 2-4). More details on the blocks 

affected by the Topographic Features Stipulation and the pinnacle trend blocks subject to the Live 

Bottom Stipulation can be found at http://www.boem.gov/Biologically-Sensitive-Areas-List/. Maps 

indicating the areas affected by the Topographic Features Stipulation, which is routinely applied to 

leases in the vicinity of certain geographic features, can be found at http://www.boem.gov/

Topographic-Features-Stipulation-Map-Package/. 
2-12 Gulf of Mexico Multisale EIS

Figure 2-4. Identified Topographic Features, Pinnacle Trend, and Blocks South of Baldwin County, 

Alabama, Stipulation Blocks in the Gulf of Mexico.

Figure 2-5 illustrates one example of the blocks that would be excluded under this 

alternative (shaded in blue). For this example, under Alternative D, there would be 15 blocks 

eliminated from the proposed lease sale area. Any production that could potentially result from 

these blocks would not be realized. Should the decisionmaker decide instead to adopt Alternatives 

A, B, or C and apply the Topographic Features Stipulation, the 15 blocks (that would have been 

eliminated from potential exploration and development under Alternative D) would be made available 

but with mitigations applied to avoid or minimize impacts to the features.
Alternatives Including the Proposed Actions 2-13

Figure 2-5. Example of Excluded Blocks under Alternative D.

As of the publication of this Multisale EIS, the Blocks South of Baldwin County, Alabama, 

Stipulation (herein referred to as the Baldwin County Stipulation Blocks) applies to a total of 

32 blocks (Mobile 826-830, 869-874, 913-918, 957-962, 1001-1006, and Viosca Knoll 33-35) within 

15-mi (24 km) of Baldwin County, Alabama (representing less than 1% of the total number of blocks 

to be offered under Alternative A or B). The intent of excluding these blocks would be to mitigate the 

visual impacts of concern raised by the Governor of Alabama on previous EISs, as well as on the 

2017-2022 Five-Year Program from which this Multisale EIS tiers. The stipulation, however, has 

been continually adopted in annual CPA lease sales since 1999 and has been considered 

satisfactorily responsive to the concern of the Governor of Alabama. The stipulation specifies 

requirements for consultation that lessees must follow when developing plans for fixed structures 

(refer to Appendix D) while still allowing leasing and OCS oil- and gas-related operations in the 

area, which could not occur with the no-leasing buffer. If any of the action alternatives are selected, 

BOEM expects this stipulation to be analyzed and decided on during each individual lease sale 
2-14 Gulf of Mexico Multisale EIS

stage in the Five-Year Program; therefore, no visual impacts would be expected to occur should the 

stipulation be applied.

Alternative D, if adopted, would prevent any OCS 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 OCS oil- and gas-related activities, which otherwise could be conducted within the blocks. 

Under Alternative D, the number of blocks that would become unavailable for lease represents only 

a small percentage of the total number of blocks to be offered under Alternative A, B, or C (<4%, 

even if blocks subject to all three stipulations were excluded). Therefore, Alternative D could reduce 

offshore infrastructure and activities by up to 4 percent when chosen in conjunction with Alternative 

A, B, or C. However, it is also possible (and BOEM believes more reasonable to expect) that 

Alternative D would only shift the location of offshore infrastructure and activities farther from these 

sensitive zones and not lead to a reduction in offshore infrastructure and activities. The regional 

impact levels for all resources, except for the topographic features and live bottoms, would be similar 

to those described under Alternative A, B, or C. All of the assumptions (including the other potential 

mitigating measures) and estimates would remain the same as described for Alternatives A, B, C. 

The analyses of impacts summarized below in Chapter 2.3 and described in detail in Chapter 4 for 

each resource are based on the development scenario, which is a set of assumptions and estimates 

on the amounts, locations, and timing for OCS exploration, development, and production operations 

and facilities, both offshore and onshore. The exclusion of this small subset of available unleased 

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

result in adverse economic effects (e.g., reduced royalties). A detailed discussion of the 

development scenario and major related impact-producing factors is included in Chapter 3. 

2.2.2.5 Alternative E—No Action

Alternative E is the cancellation of a single proposed lease sale. The opportunity for 

development of the estimated oil and gas that could have resulted from a proposed action (i.e., a 

single lease sale) or alternative to the proposed action, as described above, would be precluded or 

postponed to a future lease sale. Any potential environmental impacts resulting from a proposed 

lease sale would not occur or would be postponed. Cancellation of a proposed lease sale, however, 

would not stop all OCS oil- and gas-related activities. Activities related to previously issued leases 

and permits (as well as those that may be issued in the future under a separate decision) related to 

the OCS oil and gas program would continue. If a 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 would only be reduced by a small percentage, if 

any. Therefore, the cancellation of a proposed lease sale would not significantly change the 

environmental impacts of overall OCS oil- and gas-related activity. However, the cancellation of a 

proposed lease sale may result in direct economic impacts to the individual companies. Revenues 

collected by the Federal Government (and thus revenue disbursements to the States) would also be 

adversely affected.
Alternatives Including the Proposed Actions 2-15

The analyses of impacts summarized below in Chapter 2.3 and described in detail in 

Chapter 4 for each resource are based on the development scenario, which is a set of assumptions 

and estimates on the amounts, locations, and timing for OCS exploration, development, and 

production operations and facilities, both offshore and onshore. A detailed discussion of the 

development scenario and major related impact-producing factors is included in Chapter 3. 

2.2.3 Alternatives and Deferrals Considered but Not Analyzed in Detail

BOEM evaluated a range of alternatives to ensure that all reasonable alternatives have been

considered in this Multisale EIS. Below are the alternatives that have been considered but 

eliminated from detailed study with a brief discussion of the reasons for eliminating them.

Previous Multisale Schedule

This alternative would maintain the approach taken in the 2012-2017 Five-Year Program, 

which consisted of 12 lease sales in total, including 5 annual lease sales beginning in 2017 in the 

WPA offering all available unleased blocks, 5 annual lease sales beginning in 2018 in the CPA 

offering all available unleased blocks, and 2 lease sales in the EPA in 2014 and 2016 offering all 

available unleased blocks. No CPA or EPA blocks that are subject to Congressional moratorium 

pursuant to GOMESA would be included for leasing consideration.

While lease sales in the GOM have historically been separate annual lease sales in the CPA 

and WPA and periodic lease sales in the EPA as appropriate, significant recent energy reforms in 

Mexico have the potential to meaningfully change how exploration and development decisions are 

made in the GOM. By scheduling lease sales offering all available unleased blocks in the GOM, 

BOEM is providing more frequent opportunities to bid on rejected, relinquished, or expired OCS 

lease blocks, as well as facilitating better planning to explore resources that may straddle the 

U.S.-Mexico boundary. Furthermore, any individual lease sale could be scaled back to conform 

more closely to the traditional separate planning area model should circumstances warrant.

This Multisale EIS considers Alternatives B and C, which were similar to the previous lease 

sale approach of having lease sales for each planning area. Alternative B differs only in that the 

EPA would be combined with the CPA into a single lease sale (similar to how the two EPA lease 

sales in the 2012-2017 Five-Year Program were held concurrently with CPA lease sales). Because 

this alternative is outside the scope of the lease sale decision rather than at the Five-Year Program 

stage and as Alternatives B and C are similar to what was considered under the 2012-2017 

WPA/CPA Multisale EIS, this alternative was not considered for further analysis.

Additional Buffers

BOEM has considered a suite of alternatives that would implement additional buffer zones 

around potential areas of concern. Each of these is briefly discussed below, including the reasons 

why these additional buffer area alternatives have not been carried forward for full analysis.
2-16 Gulf of Mexico Multisale EIS

• BOEM is aware of NOAA’s proposal to expand the boundaries of the Flower 

Garden Banks National Marine Sanctuary (FGBNMS) and has considered an 

alternative that would exclude all blocks subject to that expansion from oil and 

gas leasing. The NOAA has issued an NOI to prepare an EIS for the proposed 

expansion, and BOEM is working as a cooperating agency on that EIS. The 

proposed expansion, however, is in the early stages of planning and the 

alternatives for the proposed expansion are not complete. Therefore, the 

proposed expansion of the FGBNMS is a NOAA decision that remains too 

speculative at this time to include in this Multisale EIS. Such an analysis would 

prejudge the NOAA decisionmaking process and be duplicative of the EIS being 

prepared by that agency. However, BOEM considered the areas proposed under 

the FGBNMS expansion in the analysis of other alternatives and resources in the 

2012-2017 WPA/CPA Multisale EIS, as well as in all Supplemental EISs for the 

previous 2012-2017 Five-Year Program. BOEM has existing protective 

measures in the Topographic Features Stipulation that currently protect the 

features, even those outside of the current boundaries but proposed for inclusion 

in NOAA’s expansion. In addition, BOEM protects topographic features and the 

surrounding habitat by conducting site-specific, case-by-case reviews of plans 

and permit applications in order to distance bottom-disturbing activities from 

sensitive habitat. Thus, should NOAA decide in the future to expand the 

boundaries of the FGBNMS, the only potential effect on OCS oil- and gas-related 

activities in the future would be a likely reduction of the impacts already 

considered and analyzed in the EISs. For all of these reasons, BOEM believes it 

is premature at this point to include the proposed expansion as a specific 

alternative in this Multisale EIS. If, as NOAA’s proposals for the FGBNMS 

become less speculative or reach fruition in new boundaries and use plans, 

BOEM will consider whether the proposed action and alternatives evaluated in 

future NEPA documents related to OCS leasing should be modified.

• During scoping, the Save the Manatee Club requested an alternative that would 

impose a buffer around those blocks in the EPA that are subject to 

Congressional moratorium pursuant to GOMESA. The Save the Manatee Club 

noted that, even though leasing is not allowed in these areas of the EPA, 

previous experiences such as the Deepwater Horizon explosion, oil spill, and 

response demonstrate that these areas are still at risk to potential impacts. The 

GOMESA bans oil and gas leasing within 125 mi (201 km) of the Florida 

coastline in the EPA and in a portion of the CPA until 2022. For an analysis of a 

low-probability catastrophic spill, such as the Deepwater Horizon explosion and 

oil spill, refer to the Catastrophic Spill Event Analysis white paper (USDOI, 

BOEM, 2016c). Such an event, however, is not considered reasonably 

foreseeable as a result of a proposed action. Additionally, the comments did not 

offer any well-defined buffer areas and/or reasoning to support such a buffer.
Alternatives Including the Proposed Actions 2-17

The key to managing risk is to implement a rigorous regulatory regime to ensure 

that postlease drilling activities are conducted in a safe manner. It is at this stage 

that detailed information regarding a specific proposed action is available for 

review, including reservoir characteristics, infrastructure designs, and features to 

ensure safety and reduce environmental risk. BOEM has implemented a suite of 

regulatory changes following the Deepwater Horizon explosion, oil spill, and 

response. These are discussed in detail in Chapter 3.2 and Appendix A. For 

these reasons, BOEM concluded that an alternative including an additional buffer 

around the EPA was not warranted for detailed analysis.

• The National Park Service (NPS) requested an alternative that considered a noleasing buffer within 15 mi (24 km) of the Gulf Islands National Seashore (GUIS). 

As noted in Chapter 1.1, the purpose of the proposed Federal actions is to offer 

for lease those areas that may contain economically recoverable oil and gas 

resources in accordance with the OCSLA (67 Stat. 462), as amended (43 U.S.C. 

§§ 1331 et seq.). Over time, using adaptive management practices, BOEM and 

its predecessors have proactively developed a suite of mitigating measures that 

are applied at the prelease or postlease phases of the oil and gas program to 

avoid and protect fixed biologically and culturally sensitive features, which 

includes the GUIS (Gulf Islands National Seashore Information to Lessees and 

Operators [ITL]). This ITL ensures that postlease plans submitted by lessees of 

whole and partial lease blocks within the first 12 mi (19 km) of Federal waters 

near the GUIS are reviewed by BOEM in order to minimize visual impacts from 

development operations on these blocks. The lease blocks that would be subject 

to the Gulf Islands National Seashore ITL are illustrated in Figure 2-6. This is 

consistent with the NPS’s proposed management strategy for maintaining 

optimal night sky viewing conditions, which include cooperating with partners to 

minimize intrusion of artificial light into the night scene in the national seashore 

and evaluating the impacts on the night sky caused by national seashore 

facilities (USDOI, NPS, 2011).

Based on historical leasing patterns, the proposed actions would likely only 

minimally contribute to the existing disturbances from OCS and non-OCS 

sources. To be more specific, there are currently 11 producing platform 

complexes (fixed platforms and caissons) within 7-15 mi (11-24 km) of the GUIS 

offshore the States of Louisiana, Mississippi, and Alabama. Some OCS 

platforms are visible on the horizon. Numerous OCS structures and wells have 

existed within 3-7 mi (5-11 km) of Petit Bois Island over the years. Many of these 

platforms have been removed and only three structures are currently within 

7-10 mi (11-16 km) of Petit Bois Island, which is a designated wilderness area.
2-18 Gulf of Mexico Multisale EIS

Figure 2-6. Federal OCS Blocks Subject to the Gulf Islands National Seashore Information to 

Lessees and Operators.
Alternatives Including the Proposed Actions 2-19

Section 8(g) of the OCSLA, as amended, requires a “fair and equitable” 

distribution of revenues between the Federal Government and a coastal state for 

Federal lease blocks within 3 mi (5 km) of the seaward boundary of the State that 

may contain oil and gas reservoirs underlying both OCS and submerged State 

tidelands. Due to the location of the GUIS, the proposed buffer area includes 

blocks off the coasts of Louisiana, Mississippi, and Alabama, and could result in 

reduced revenue sharing for those States as a result of the alternative being 

chosen. Consultation with the Governor of each State is required at the time of 

soliciting nominations for the leasing of OCS lands wholly or partially within the 

3 mi (5 km) mentioned above. The GOMESA enhances the revenue sharing 

provisions for the four Gulf oil- and gas-producing States of Alabama, Louisiana, 

Mississippi, and Texas, and their coastal political subdivisions, which are to be 

used for coastal conservation, restoration, and hurricane protection.

Even without the presence of oil and gas activities in State waters and on the 

Federal OCS, there is substantial vessel traffic in this area due to the presence of 

federally designated shipping safety fairways and anchorage areas to provide 

unobstructed approaches for vessels using U.S. ports (33 CFR part 166). These 

visual impacts would remain ongoing and unaffected by the proposed actions. 

Because of the environmental protection measures already implemented by 

BOEM and BSEE through the established ITL for the subject area, this 

alternative was not analyzed in detail in this Multisale EIS.

To exclude the additional buffer areas proposed above from potential oil and gas exploration 

and development would not achieve the desired goal of reducing risk in the search for offshore oil 

and gas resources. The purpose of and need for the oil and gas leasing program is to help meet the 

Nation’s energy needs by developing those resources in a manner consistent with environmental 

protection and the laws and policies of affected States. Additional buffers would result in a scenario 

where there would be little to no change in the assessment of potential environmental damage and 

safety concerns on the OCS; however, there could be adverse effects to the economic benefits of a 

lease sale. Based on the information presented above, BOEM has determined that an alternative 

that would impose the proposed buffer areas will not decrease the risk associated with drilling, would 

not achieve the desired goal of reducing risk or environmental impacts, and may be detrimental to 

the recovery of OCS oil and gas resources in the long term. It does not meet the purpose of and 

need for the proposed actions and, therefore, these alternatives have not been retained for detailed 

analysis.

Lease Sale Offering Only EPA Available Unleased Blocks

This alternative would allow for a proposed lease sale encompassing the EPA within the U.S. 

portion of the Gulf of Mexico OCS. Available unleased blocks within the CPA and WPA would not

be considered under this alternative. This alternative would offer for lease all available unleased 

blocks within the EPA portion of the proposed lease sale area for oil and gas operations with the 

exception of whole and portions of blocks deferred by the Gulf of Mexico Energy Security Act of 
2-20 Gulf of Mexico Multisale EIS

2006. During scoping, the Save the Manatee Club requested NEPA analysis of the EPA in a 

separate process. The Save the Manatee Club noted that the EPA has unique environmental and 

cultural resources, and has heretofore only been minimally impacted by drilling operations in the Gulf 

of Mexico. Any potential impacts to resources exclusive or more prevalent to the EPA (e.g., 

manatees and Gulf sturgeon) have been considered in the alternatives analyses.

The proposed EPA portion of the lease sale area covers approximately 657,905 ac and 

includes those blocks previously included in the EPA Lease Sales 225 and 226 areas, which is 

bordered by the CPA boundary on the west and the Military Mission Line (86o41′ W. longitude) on 

the east. The area is south of eastern Alabama and western Florida; the nearest point of land is 

125 mi (201 km) northwest in Louisiana. As of March 2016, approximately 595,475 ac (70%) and 

162 lease blocks of the proposed EPA lease sale area are currently unleased. From a leasing 

perspective, it is less practical to conduct separate lease sales for the EPA due to its size (i.e., the 

number of blocks available for lease) and considering the leasing history in this area. Although 

recent leasing in the EPA has been minimal, providing these blocks more frequently through a 

regionwide approach would more effectively balance Agency workload and provide greater flexibility 

to industry, including the ability to respond to the significant recent energy reforms in Mexico that 

have the potential to meaningfully change how exploration and development decisions are made in 

the GOM.

Although the majority of the EPA is unavailable for leasing through June 30, 2022, under 

GOMESA, there are existing leases in the planning area. Thirteen lease sales have been held in 

this planning area as it has been configured over the years, and 105 wells have been drilled, with 

significant discoveries of natural gas. However, there has been no production from the wells in the 

planning area as currently configured. Lease Sale 224 in March 2008 resulted in leases being 

awarded on 36 OCS blocks with bonuses totaling $64.7 million in the small area available for leasing 

consideration. The most recent lease sale held in the same small area was Lease Sale 225 in 

March 2014, and no bids were received. One lease sale remains on the 2012-2017 Five-Year 

Program schedule for 2016.

Regionwide OCS Lease Sale with Additional Mitigating Measures for Sperm Whale High-Use 

Areas

Sperm whales, protected under the ESA, often concentrate in the deepwater area offshore 

the Mississippi River delta, especially in the vicinity of the Mississippi Canyon and adjacent 

continental slope. During scoping for the 2017-2022 Five-Year Program EIS, the Center for 

Biological Diversity requested special consideration of the Mississippi Canyon area to protect 

potential important sperm whale habitat. This was not analyzed as an alternative because current 

long-term biological data do not support the need for exclusion or additional mitigations beyond what 

currently exists. A full analysis of marine mammals, including sperm whales, can be found in 

Chapter 4.9.1. 
Alternatives Including the Proposed Actions 2-21

Delay Leasing Until the State of the Gulf of Mexico Environmental Baseline is Known

This suggested alternative would address comments raised that the state of recovery of the 

Gulf of Mexico environmental baseline following the Deepwater Horizon explosion, oil spill, and 

response has not yet been fully determined and that BOEM should delay leasing until missing 

information is known, or at least for several years. The basis for this alternative is the concern that 

additional leasing could contribute to an incremental increase in the chance of another lowprobability catastrophic oil spill or that cumulative impacts could have devastating environmental 

effects on an ecosystem that is still recovering from a previous event. It should be noted that, 

because of the dynamic nature of the Gulf of Mexico, the environmental baseline is not static and is 

constantly changing due to a variety of natural and anthropogenic factors. This would be true even if 

the Deepwater Horizon explosion, oil spill, and response had not occurred, and it remains to be seen 

if many impacts of the Deepwater Horizon explosion, oil spill, and response can be identified and 

studied in isolation from the other ongoing and systemic processes in the Gulf of Mexico. This 

Multisale EIS has taken into account that there remains incomplete information and that an Agency 

will likely never have complete and perfect information available to it at the time of a decision, and 

indeed that is the purpose of 40 CFR § 1502.22 of the CEQ regulations, which allows an agency to 

evaluate the information that is available and proceed in light of incomplete or unavailable 

information. It should also be noted that this option of delaying leasing is already incorporated into 

the No Action Alternative that is analyzed in this Multisale EIS. At the time of the lease-sale 

decision, the Assistant Secretary for Land and Minerals Management can choose the No Action 

Alternative for any of the lease sales covered in this Multisale EIS. This would result in a delay of 

leasing, potentially until the next scheduled lease sale in the current Five-Year Program or beyond, 

where again the Assistant Secretary for Land and Minerals Management can choose the No Action 

Alternative.

In addition, credible scientific data regarding the potential short-term and long-term impacts 

of the Deepwater Horizon explosion, oil spill, and response on Gulf of Mexico resources is becoming 

available but remains incomplete at this time. It could be many years before this information 

becomes available via the Natural Resource Damage Assessment (NRDA) process, BOEM’s 

Environmental Studies Program, and numerous studies by other Federal and State agencies and 

academia. Nonetheless, the subject-matter experts that prepared this Multisale EIS acquired and 

used new scientifically credible information that was available, determined that additional information 

was not available absent exorbitant expenditures or could not be obtained regardless of cost in a 

timely manner, and where gaps remained, exercised their best professional judgment to extrapolate 

baseline conditions and impact analyses using accepted methodologies based on credible 

information. This approach complies with the requirements of §1502.22 of the CEQ regulations 

regarding how agencies should address incomplete or unavailable information.

The references for Chapters 1-5 are dominated by scientific research. In the vast majority of 

these references, the methods used to conduct the research are spelled out. These references are 

publicly available and the “scientific methodologies of research and modeling” would be too 

extensive to detail in an EIS. However, in numerous places in this Multisale EIS, where it was 
2-22 Gulf of Mexico Multisale EIS

Mitigating measures 

considered in this NEPA 

document rely primarily on 

avoiding an impact altogether 

by not allowing certain actions 

or parts of an action.

considered important, specific methodologies were summarized. For example, the use of in-situ

fluorescence and oxygen measurements as proxies for oil concentration and biodegradation to track 

the subsurface plume of oil from the Deepwater Horizon explosion and oil spill was included in this 

Multisale EIS where appropriate.

In addition, BOEM’s catastrophic analysis, Catastrophic Spill Event Analysis white paper, 

provides more information about general impacts of a low-probability catastrophic oil spill (USDOI, 

BOEM, 2016c). A low-probability catastrophic oil spill is not reasonably foreseeable and not part of 

a proposed action; however, it should be noted that the catastrophic analysis is intended to be a 

general overview of the potential effects of a catastrophic spill and to complement the substantive 

analyses of accidental events (noncatastrophic) presented in the main body of the EIS. As such, the 

Catastrophic Spill Event Analysis white paper should be read with the understanding that further 

detail about oil impacts from more reasonably foreseeable accidents on a particular resource can be 

found in the main body of this Multisale EIS or previous relevant NEPA documents. Given the 

above, BOEM has determined that this suggested alternative does not require additional analysis in 

this Multisale EIS, distinct and apart from the No Action Alternative already considered.

2.2.4 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.

• 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.

BOEM considers the use of mitigation at all phases of energy development and planning, 

from the overarching Five-Year Program EIS, through each of the NEPA documents for the lease 

sales, and followed by more site-specific reviews for exploration, development and production, and 
Alternatives Including the Proposed Actions 2-23

BOEM and its predecessors 

have protected topographic 

features since 1973 through 

the use of the Topographic 

Features Stipulation. 

platform removal plans (Figure 1-2). Through this approach, BOEM is able to analyze impacts and 

mitigations that are ripe for consideration at the appropriate time. Mitigations can be applied at the 

prelease stage, typically through applying lease stipulations or at the postlease stage by applying 

site-specific mitigating measures to plans, permits, and/or authorizations. BOEM assigns 

site-specific mitigation by imposing conditions of approval on a plan, permit, or authorization.

2.2.4.1 Proposed Prelease Mitigating Measures (Stipulations)

The potential lease stipulations and mitigating measures included for analysis in this 

Multisale EIS were developed as a result of numerous scoping efforts for the continuing OCS 

Program in the Gulf of Mexico. The 10 lease stipulations described below would be considered at 

the prelease stage, as applicable, to any proposed lease sale. These measures will be considered 

for adoption by the ASLM under authority delegated by the Secretary of the Interior. The analysis of 

any stipulations for any particular alternative does not ensure that the ASLM will make a decision to 

apply the stipulations to leases that may result from any proposed lease sale nor does it preclude 

minor modifications in wording during subsequent steps in the prelease process if comments 

indicate changes are necessary or if conditions change. Any stipulations or mitigation requirements 

to be included in a proposed lease sale will be described in the Record of Decision for that proposed 

lease sale. Appendix D provides a more detailed analysis of the 10 lease stipulations and their 

effectiveness.

Topographic Features Stipulation

The topographic features located in the WPA and CPA 

provide habitat for coral-reef-community organisms (Chapter 

4.1.1.6). There are currently no identified topographic features 

protected under this stipulation in the EPA. The OCS oil- and 

gas-related activities resulting from a proposed action could 

have a severe, even lethal, impact on or near these communities 

if the Topographic Features Stipulation is not adopted and such 

activities are not otherwise mitigated. The blocks affected by the Topographic Features Stipulation 

are shown in Figure 2-4. 

The stipulation establishes No Activity Zones at the topographic features. Outside the No 

Activity Zones, additional restrictive zones are established where oil and gas operations could occur, 

but where drilling discharges would be shunted. Monitoring studies have demonstrated that the 

shunting requirements of the stipulations are effective in preventing the muds and cuttings from 

impacting the biota of the banks. The stipulation would prevent or minimize damage to the biota of 

the banks from routine OCS oil- and gas-related activities resulting from a proposed action, while 

allowing the development of nearby oil and gas resources, specifically as discussed in Appendix D. 
2-24 Gulf of Mexico Multisale EIS

BOEM has effectively 

managed and avoided 

space-use conflicts with 

military activities in the Gulf of 

Mexico since the early 1970s. 

Live Bottom (Pinnacle Trend) Stipulation

For the purpose of this stipulation, “live bottom areas” are defined as seagrass communities 

or those areas that contain biological assemblages consisting of sessile invertebrates such as sea 

fans, sea whips, hydroids, anemones, ascidians, sponges, bryozoans, or corals living upon and 

attached to naturally occurring hard or rocky formations with rough, broken, or smooth topography; 

or areas whose lithotope favors the accumulation of turtles, fishes, and other fauna. Live bottom 

features may include pinnacle trend features, low-relief features, or potentially sensitive biological 

features. This stipulation would be applied to protect both pinnacle trend features (i.e., Live Bottom 

[Pinnacle Trend] Stipulation) and/or low-relief features (i.e. Live Bottom [Low Relief] Stipulation); 

however, blocks subject to the Live Bottom (Low Relief) Stipulation are not included as part of the 

proposed action for this Multisale EIS. The Live Bottom (Pinnacle Trend) Stipulation would protect 

live bottom features (Pinnacle Trend features) from routine OCS oil- and gas-related activity by 

distancing bottom-disturbing activity (e.g., anchors, chains, cables, and wire ropes) 30 m (100 ft) 

from hard bottoms/pinnacles. The Live Bottom (Pinnacle Trend) Stipulation is intended to protect 

live bottom features (Pinnacle Trend features) from damage and, at the same time, provide for the 

recovery of potential oil and gas resources. 

Military Areas Stipulation

The Military Areas Stipulation has been applied to all 

blocks leased in military areas since 1977 and reduces potential 

impacts, particularly in regards to safety, but it does not reduce 

or eliminate the actual physical presence of OCS oil- and 

gas-related 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 2-7 shows the military warning areas in the Gulf of Mexico.

Figure 2-7. Military Warning Areas and Eglin Water Test Areas in the Gulf of Mexico.
Alternatives Including the Proposed Actions 2-25

Evacuation Stipulation

This stipulation would be a part of any lease in the easternmost portion of the CPA and all 

blocks leased in the EPA portion of the proposed lease sale area resulting from a proposed action. 

An evacuation stipulation has been applied to all blocks leased in these areas since 2001. The 

Evacuation Stipulation is designed to protect the lives and welfare of offshore oil and gas personnel. 

The OCS oil- and gas-related activities have the potential to occasionally interfere with specific 

requirements and operating parameters for the lessee’s activities in accordance with the military 

stipulation clauses contained herein. If it is determined that the operations will result in interference 

with scheduled military missions in such a manner as to possibly jeopardize the national defense or 

to pose unacceptable risks to life and property, then a temporary suspension of operations and the 

evacuation of personnel may be necessary.

Coordination Stipulation

This stipulation would be a part of any lease in the easternmost portion of the CPA and all 

blocks leased in the EPA portion of the proposed lease sale area resulting from a proposed action. 

A coordination stipulation has been applied to all blocks leased in these areas since 2001. The 

Coordination Stipulation is designed to increase communication and cooperation between military 

authorities and offshore oil and gas operators. Specific requirements and operating parameters are 

established for the lessee’s activities in accordance with the military stipulation clauses. For 

instance, if it is determined that the operations will result in interference with scheduled military 

missions in such a manner as to possibly jeopardize the national defense or to pose unacceptable 

risks to life and property, then certain measures become activated and the OCS oil- and gas-related 

operations may be curtailed in the interest of national defense.

Blocks South of Baldwin County, Alabama, Stipulation

This stipulation would be included only on leases on blocks south of and within 15 mi (24 km) 

of Baldwin County, Alabama. The stipulation specifies requirements for consultation that lessees 

must follow when developing plans for fixed structures. The stipulation has been continually 

adopted in annual CPA lease sales since 1999. It has been considered satisfactorily responsive to

the concern of the Governor of Alabama and was adopted in each of the CPA lease sales in the 

2002-2007 and 2007-2012 Five-Year Programs.

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.
2-26 Gulf of Mexico Multisale EIS

United Nations Convention on the Law of the Sea Royalty Payment Stipulation

If the United States becomes a party to the 1982 United Nations Convention on the Law of 

the Sea (UNCLOS) prior to or during the life of a lease issued by the United States on a block or 

portion of a block located beyond its Exclusive Economic Zone as defined in UNCLOS and subject 

to such conditions that the Senate may impose through its constitutional role of advice and consent, 

then the royalty payment lease provisions will apply to the lease so issued, consistent with Article 82 

of UNCLOS.

Below Seabed Operations Stipulation

The Below Seabed Operations Stipulation language is intended to be lease sale-specific 

language and would incorporate maps of the potentially affected blocks containing rights-of-use and 

easements. This stipulation is designed to minimize or avoid potential space-use conflicts with 

moored and/or floating production facilities that have already been granted rights-of-use and 

easements in particular OCS blocks.

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

States Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico 

(Transboundary Stipulation)

The “Agreement between the United States of America and the United Mexican States 

Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico” (Agreement) was signed 

on February 20, 2012, and entered into force on July 18, 2014. 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 Agreement. A copy of the Agreement can be 

found on BOEM’s website at http://www.boem.gov/BOEM-Newsroom/Library/BoundariesMexico.aspx.

Summary

These measures would be considered for adoption by the ASLM at the prelease stage, as 

applicable, under authority delegated by the Secretary of the Interior. The analysis of any 

stipulations for any particular alternative does not ensure that the ASLM will make a decision to 

apply the stipulations to leases that may result from any proposed lease sale nor does it preclude 

minor modifications in wording during subsequent steps in the prelease process if comments 

indicate changes are necessary or if conditions change.

Any stipulations or mitigation requirements to be included in a lease sale will be described in 

the Record of Decision 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 related to leases issued as a 
Alternatives Including the Proposed Actions 2-27

Mitigating measures are a 

standard part of BOEM’s program 

to ensure that operations are 

always conducted in an 

environmentally sound manner.

Mitigating measures are a 

standard part of BOEM’s program 

to ensure that operations are 

always conducted in an 

environmentally sound manner.

result of a lease sale, will undergo a NEPA review, and additional project-specific mitigations applied 

as conditions of plan approval at the postlease stage. The BSEE has the authority to monitor and 

enforce these conditions under 30 CFR part 250 subpart N and may seek remedies and penalties 

from any operator that fails to comply with those conditions, stipulations, and mitigating measures.

2.2.4.2 Prelease Mitigating Measures (Stipulations) by Alternative

Table 2-1 indicates what stipulations could be applied for each alternative. Alternative D 

would consider the same stipulations as Alternative A, B, or C, as applicable, with the exception of 

removing the Topographic Features and Live Bottoms (Pinnacle Trend) Stipulations since all blocks 

subject to these stipulations would not be made available. Since Alternative E is the cancellation of 

a proposed lease sale no stipulations would apply.

Table 2-1. Applicable Stipulations by Alternative. (Stipulations that would apply to specific lease blocks 

under any given alternative are marked with an X. Stipulations that would not apply are 

marked “–”. Because Alternative E would cancel a proposed lease sale, no leasing activities 

would occur and, therefore, no stipulations would apply.)

Stipulation Alternative A Alternative B Alternative C Alternative D Alternative E

Topographic 

Features X X X – – 

Live Bottoms X X – – – 

Military Areas X X X X –

Evacuation X X – See A, B, or C – 

Coordination X X – See A, B, or C – 

Blocks South of 

Baldwin County, 

Alabama

X X – See A, B, or C – 

Protected Species X X X X – 

United Nations 

Convention on the 

Law of the Sea 

Royalty Payment

X X X X – 

Below Seabed 

Operations X X – See A, B, or C – 

Transboundary X X X X –

2.2.4.3 Postlease Mitigating Measures

This chapter discusses mitigating measures that 

could be applied by BOEM during site-specific plan and/or 

permit reviews. Mitigating measures have been proposed, 

identified, evaluated, or developed through previous BOEM 

lease sale NEPA reviews and analyses. Many of these 

mitigating measures have been adopted and incorporated 

into regulations and/or as guidelines governing OCS 
2-28 Gulf of Mexico Multisale EIS

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 the operations 

are always conducted in an environmentally sound manner (with an emphasis on avoiding or 

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 and avoidance of archaeological sites and biologically sensitive areas such as 

pinnacles, topographic features, and chemosynthetic communities.

Some BOEM-identified mitigating measures are incorporated into OCS oil- and gas-related 

operations through cooperative agreements or efforts with industry and State and Federal agencies. 

These mitigating measures include NMFS’s Observer Program to protect marine mammals and sea 

turtles during explosive removals, labeling operational supplies to track possible sources of debris or 

equipment loss, development of methods of pipeline landfall to eliminate impacts to beaches or 

wetlands, and beach cleanup events.

Site-specific mitigating measures are also applied by BOEM during plan and permit reviews. 

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). Categories of sitespecific mitigations include the following: air quality; archaeological resources; artificial reef material; 

chemosynthetic communities; Flower Garden Banks; topographic features; hard 

bottoms/pinnacles/potentially sensitive biological features; 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 the following: 

advisories; conditions of approval; hazard survey reviews; inspection requirements; notifications; 

post-approval submittals; and safety precautions. In addition to standard mitigations, BOEM may 

also apply nonrecurring mitigating measures that are developed on a case-by-case basis. Refer to 

Appendix B (“Commonly Applied Mitigating Measures”) for more information on the mitigations that 

BOEM and BSEE typically apply to plans and/or permits.

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).
Alternatives Including the Proposed Actions 2-29

2.2.5 Issues

Issues are defined by CEQ to represent those principal “effects” that an EIS should evaluate 

in-depth. Scoping identifies specific environmental resources and/or activities rather than “causes” 

as significant issues (Council on Environmental Quality, 1981). The analysis in the EIS can then 

show the degree of change from the present conditions for each issue to the actions related to a 

proposed action.

Selection of environmental and socioeconomic issues to be analyzed was based on the 

following criteria:

• issue is identified in CEQ regulations as subject to evaluation;

• the relevant resource/activity was identified through agency expertise, through 

the scoping process, or from comments on past 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 

impact-producing factor should exist; or

• information that indicates a need to evaluate the potential impacts to a 

resource/activity has become available.

2.2.5.1 Issues to be Analyzed

The following issues relate to potential impact-producing factors and the resources and 

activities that could be affected by OCS exploration, development, production, and transportation 

activities.

Accidental Events: Concerns were raised related to the potential impact of oil spills, 

including the Deepwater Horizon explosion, oil spill, and response, on the marine and coastal 

environments, specifically regarding the potential effects of oil spills on tourism, emergency

response capabilities, spill prevention, effect of winds and currents on the transport of oil spills, 

accidental discharges from both deepwater losses of well control and pipeline ruptures, and oil spills 

resulting from past and future hurricanes. Other concerns raised over the years of scoping were the 

fate and behavior of oil spills, availability and adequacy of oil-spill containment and cleanup 

technologies, oil-spill cleanup strategies, impacts of various oil-spill cleanup methods, effects of 

weathering on oil spills, toxicological effects of fresh and weathered oil, air pollution associated with 

spilled oil, and short-term and long-term impacts of oil on wetlands.

After the Deepwater Horizon explosion, oil spill, and response, BOEM prepared a 

“Catastrophic Spill Event Analysis,” which was previously included as an appendix to the 2012-2017 

WPA/CPA Multisale EIS and the subsequent Supplemental EISs. This analysis has since been 

published as an independent white paper and can be found on BOEM’s website (USDOI, BOEM, 
2-30 Gulf of Mexico Multisale EIS

2016c). The purpose of this technical analysis is to assist BOEM in the preparation of robust 

environmental analyses of the proposed actions. The CEQ guidance addresses impacts with 

catastrophic consequences in the context of evaluating reasonably foreseeable significant adverse 

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

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

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

is supported by credible scientific evidence, is not based on pure conjecture, and is within the rule of 

reason” (40 CFR § 1502.22(b)(4)). Therefore, this analysis, which is based on credible scientific 

evidence, identifies the most likely and most significant impacts from a high-volume blowout and oil 

spill that continues for an extended period of time. Such a catastrophic event is not reasonably 

foreseeable and not part of a proposed action; but, in line with CEQ guidance (CEQ, 2010), the 

reasonably foreseeable impacts that could result in the exceedingly unlikely event that such a spill 

were to occur are analyzed in the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 

2016c). The scenario and impacts discussed in this analysis should not be confused with the 

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

smaller accidental events of a proposed action.

Drilling Fluids and Cuttings: Specific concerns related to drilling fluids include mercury, 

synthetic-based drilling fluids (SBFs) and large volumes of industrial chemicals necessary for 

deepwater drilling operations, and potential for persistence of drilling muds and cuttings. Other 

concerns raised over the years of scoping were potential smothering of benthic communities by 

offshore disposal of drilling fluids and cuttings, the use and disposal of drilling fluids include potential 

spills of oil-based drilling fluids (OBFs), onshore disposal of OBFs, the fate and effects of SBFs in 

the marine environment, and the potential toxic effects or bioaccumulation of trace metals in drilling 

fluids discharged into the marine environment.

Visual and Aesthetic Interference: Lighting was raised as a specific concern. Concerns 

raised over the years of scoping were the potential effects of the presence of drilling rigs and 

platforms, service vessels, helicopters, trash and debris, and flaring on visual aesthetics. 

Air Emissions: The potential effects of emissions of combustion gases from platforms, drill 

rigs, service vessels, and helicopters have been raised as an issue over the years of scoping. Also 

under consideration are the flaring of produced gases during extended well testing and the potential 

impacts of the transport of production with associated hydrogen sulfide (H2S).

Water Quality Degradation: Issues related to water quality degradation raised over the years 

of scoping most often were associated with operational discharges of drilling muds and cuttings, 

produced waters, and domestic wastes. Water quality issues also included concerns related to 

impacts from sediment disturbance, petroleum spills and blowouts, and discharges from service 

vessels. 

Other Wastes: Other concerns raised over the years of scoping include storage and 

disposal of trash and debris, and trash and debris on recreational beaches.
Alternatives Including the Proposed Actions 2-31

Structure and Pipeline Emplacement: Some of the issues raised over the years of scoping 

related to structure and pipeline emplacement are bottom area disturbances from bottom-founded 

structures or anchoring, sediment displacement related to pipeline burial, space-use conflicts, and 

the vulnerability of offshore pipelines to damage that could result in hydrocarbon spills or H2S leaks.

Platform Removals: Concerns raised over the years of scoping about the abandonment of 

operations include how a platform is removed, the potential impacts of explosive severance and 

removals on marine organisms, the remaining operational debris snagging fishing nets, and siteclearance procedures.

OCS Oil- and Gas-Related Support Services, Activities, and Infrastructure: Specific issues 

were damage to coastal infrastructure by past hurricane activity and the vulnerability of coastal 

infrastructure to damage from future hurricanes. Concerns raised over the years of scoping include 

activities related to the shore-based support of the development and production plan include vessel 

and helicopter traffic and emissions, construction or expansion of navigation channels or onshore 

infrastructure, maintenance and use of navigation channels and ports, and deepening of ports.

Sociocultural and Socioeconomic: Many concerns have focused on the potential impacts to 

coastal communities, including demands on public services and tourism. Issues raised from years of 

scoping include impacts on employment, population fluctuations, effects on land-use impacts to lowincome or minority populations, and cultural impacts.

Geological and Geophysical Activities: Specific issues were noise impacts related to seismic 

airgun surveys on marine mammals, sea turtles, fisheries, and other resources. Other concerns 

include vessel strikes with marine mammals and sea turtles, as well as concerns regarding potential 

space-use conflicts.

Other Issues: Many other issues have been identified. Several of these issues are subsets 

or variations of the issues listed above. All are taken under advisement and are considered in the 

analyses, if appropriate. Additional issues raised during scoping are consideration of the extensive 

safety improvements implemented since the Deepwater Horizon explosion, oil spill, and response; 

noise from platforms, vessels, and helicopters; turbidity as a result of seafloor disturbance or 

discharges; and damage to biota and habitats.

Resource Topics Analyzed in This Multisale EIS: The analyses in Chapters 4.1-4.5 address 

the issues and concerns identified above under the following resource topics:
2-32 Gulf of Mexico Multisale EIS

− Air Quality

− Water Quality (Coastal and Offshore)

− Coastal Habitats (Estuarine Systems and 

Coastal Barrier Beaches and Associated 

Dunes)

− Deepwater Benthic Communities 

(Chemosynthetic and Deepwater Coral)

− Sargassum and Associated Communities

− Live Bottoms (Topographic Features, 

Pinnacles, and Low-Relief Features)

− Fishes and Invertebrate Resources

− Birds

− Protected Species (ESA Listed Marine 

Mammals, Sea Turtles, Beach Mice, 

Protected Birds, and Protected Corals)

− Commercial Fisheries

− Recreational Fishing

− Recreational Resources

− Archaeological Resources (Historic and 

Prehistoric)

− Human Resources and Land Use 

(Land Use and Coastal Infrastructure, 

Economic Factors, and Social Factors, 

Including Environmental Justice)

2.2.5.2 Issues Considered but Not Analyzed

As previously noted, the CEQ regulations for implementing NEPA instruct agencies to adopt 

an early process (termed “scoping”) for determining the scope of issues to be addressed and for 

identifying significant issues related to a proposed action. As part of this scoping process, agencies 

shall identify and eliminate from detailed study the issues that are not significant to the proposed 

action or have been covered by prior environmental review.

Through our scoping efforts, numerous issues and topics were identified for consideration in 

this Multisale EIS. The following categories were considered not to be significant issues related to a 

proposed action or have been covered by prior environmental review.

Program and Policy Issues

Comments and concerns that relate to program and policy are issues under the direction of 

the U.S. Department of the Interior and/or BOEM’s guiding regulations, statutes, and laws. The 

comments and concerns related to program and policy issues are not considered to be specifically 

related to the proposed actions. For example, the Louisiana Department of Natural Resources, 

Office of Coastal Management requested in their scoping comments that this Multisale EIS make 

provisions for compensatory mitigation for all lease sale impacts. Such comments are forwarded to 

the appropriate program offices for their consideration. Programmatic issues including expansion of 

the proposed lease sale area, administrative boundaries, and royalty relief have been considered in 

the preparation of the Draft Five-Year Program EIS (USDOI, BOEM, 2016b).

Revenue Sharing

A number of comments were received on previous EISs from State and local governments, 

interest groups, and the general public stating that locally affected communities should receive an 

increased share of revenues generated by the OCS oil and gas leasing program. In particular to the 

GOM, Louisiana reiterated continued concerns that Louisiana’s coastal wetlands are 

disproportionately bearing the impacts from OCS oil- and gas-related activities and that BOEM 

should make provisions for appropriate compensatory mitigation related to OCS lease sale activities. 
Alternatives Including the Proposed Actions 2-33

Comments and concerns that relate to the use and distribution of revenues are issues under the 

direction of the U.S. Congress or the Department of the Interior and their guiding regulations, 

statutes, and laws.

On October 1, 2010, the revenue collection function of the Bureau of Ocean Energy 

Management, Regulation and Enforcement (BOEM’s predecessor) became the independent Office 

of Natural Resource Revenue. The Office of Natural Resource Revenue distributes revenues 

collected from Federal mineral leases to special-purpose funds administered by Federal agencies, to 

States, and to the General Fund of the U.S. Department of the Treasury. Legislation and regulations 

provide formulas for the disbursement of these revenues. With the enactment of GOMESA, the Gulf 

producing States (i.e., Texas, Louisiana, Mississippi, and Alabama) and their coastal political 

subdivisions (CPSs) were granted an increased share of offshore oil and gas revenue. Beginning in 

FY 2007, and thereafter, Gulf producing States and their CPSs received 37.5 percent of the qualified 

OCS revenue from new leases, including bonus bids, rentals, and production royalty, issued in the 

181 Area in the EPA and in the 181 South Area, which is located from 100 mi (161 km) offshore from 

the Alabama-Florida State line and over 285 mi (459 km) from Tampa, Florida. Beginning in 

FY 2016 and through 2055, Gulf producing States and their CPSs will receive 37.5 percent and the 

Land and Water Conservation Fund will receive 12.5 percent of qualified OCS revenue from new 

leases in the existing areas available for leasing, subject to a $500 million cap. The remaining 

50 percent of qualified OCS revenues and revenues exceeding the $500 million cap will be 

distributed to the U.S. Treasury.

The socioeconomic benefits and impacts to local communities are analyzed in Chapter 

4.14.3. 

2.3 COMPARISON OF IMPACTS BY ALTERNATIVE

Table 2-2 provides a comparison of expected impact levels by alternative and is derived 

from the analysis of each resource in Chapter 4. The impact level ratings have been specifically 

tailored and defined for each resource within the Chapter 4 impact analysis. BOEM has concluded 

that the selection of Alternative E would result in no additional discernible impacts to the resources 

analyzed; therefore, Alternative E ratings were not included. Cumulative impacts of current and past 

activities, however, would continue to occur under Alternative E.

Table 2-2. Alternative Comparison Matrix.

Impact Level Key

Beneficial Negligible Minor Moderate Major

Resource Alternative A Alternative B Alternative C Alternative D

Air Quality Minor Minor Minor Minor

Water Quality Minor Minor Minor Minor

Estuarine Systems Minor Negligible Negligible Negligible to

Minor
2-34 Gulf of Mexico Multisale EIS

Impact Level Key

Beneficial Negligible Minor Moderate Major

Resource Alternative A Alternative B Alternative C Alternative D

Coastal Barrier Beaches 

and Associated Dunes Negligible Negligible Negligible Negligible

Deepwater Benthic 

Communities

Negligible to Negligible to Negligible to Negligible to 

Minor Minor Minor Minor

Sargassum and Associated 

Communities Negligible Negligible Negligible Negligible

Live Bottoms

Topographic Features

Negligible to Negligible to Negligible to

Negligible Minor Minor Minor

Pinnacles and Low-Relief 

Features

Negligible to Negligible to Negligible to Negligible Minor Minor Minor

Fishes and Invertebrate 

Resources

Negligible to Negligible to Negligible to Negligible to 

Moderate Moderate Moderate Moderate

Birds Moderate Moderate Moderate Moderate

Protected Species

Marine Mammals

Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate

Sea Turtles Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate

Beach Mice Negligible Negligible Negligible Negligible

Protected Birds Negligible to Negligible to Negligible to Negligible to 

Moderate Moderate Moderate Moderate

Protected Corals Negligible to Negligible to Negligible to Negligible to 

Minor Minor Minor Minor

Commercial Fisheries Beneficial to Beneficial to Beneficial to Beneficial to 

Minor Minor Minor Minor

Recreational Fishing Negligible to Negligible to Negligible to Negligible to 

Minor Minor Minor Minor

Recreational Resources Beneficial to Beneficial to Beneficial to Beneficial to 

Minor Minor Minor Minor

Archaeological Resources Negligible Negligible Negligible Negligible

Human Resources and Land 

Use

Land Use and Coastal 

Infrastructure

Negligible to Negligible to Negligible to Negligible to

Major Major Major Major

Economic Factors Negligible to Negligible to Negligible to Negligible to 

Minor Minor Minor Minor

Social Factors (including 

Environmental Justice) Minor Minor Minor Minor

BOEM has concluded that the selection of Alternative E would result in no additional discernible impacts 

to the resources analyzed; however, cumulative impacts of current, past and reasonably foreseeable 

future activities could continue to occur.
Alternatives Including the Proposed Actions 2-35

2.4 SUMMARY OF IMPACTS

Presented here is an overall summary of impacts for each resource with a more detailed 

analysis of impacts for each resource from the proposed action, as presented in Chapter 4. 

2.4.1 Air Quality

Air quality is the degree at which the ambient air is free of pollution; it is assessed by 

measuring the pollutants in the air. To protect public health and welfare, the Clean Air Act 

established national ambient air quality standards for certain common and widespread pollutants. 

The seven common "criteria pollutants" are particle pollution (also known as particulate matter, PM2.5

and PM10), carbon monoxide (CO); nitrogen dioxide (NO2); sulfur dioxide (SO2); lead (Pb); and 

ozone (O3). Air emissions from OCS oil and gas development in the Gulf of Mexico would arise from 

emission sources related to drilling and production with associated vessel support, flaring and 

venting, decommissioning, fugitive emissions, and oil spills. Associated activities that take place as 

a result of a proposed action support and maintain the OCS oil and gas platform sources. Air 

emissions from non-OCS oil- and gas-related emissions in the Gulf of Mexico would arise from 

emission sources related to State oil and gas programs, onshore industrial and transportation 

sources, and natural events. Since the primary National Ambient Air Quality Standards are 

designed to protect human health, BOEM focuses on the impact of these activities on the States, 

where there are permanent human populations.

Based on Year 2008 and Year 2011 OCS emission inventories, postlease 1-hour NOx

modeling, and past studies, emissions of pollutants into the atmosphere from routine activities and 

accidental events associated with the OCS Program are projected to be minor. Additionally, 

reductions in emissions have been achieved through the use of low sulfur fuels, catalytic reduction, 

and other efforts. The incremental contribution of a single regionwide proposed lease sale to the 

cumulative impacts would be minor for any of the action alternatives. Portions of the Gulf Coast 

onshore areas have ozone levels that exceed the Federal air quality standard, but the incremental 

contribution from a regionwide proposed lease sale would be very small. The cumulative 

contribution to visibility impairment from a regionwide proposed lease sale is also expected to be 

very small. A full analysis of air quality can be found in Chapter 4.1. 

2.4.2 Water Quality

Water quality is a term used to describe the condition or environmental health of a waterbody 

or resource, reflecting its particular biological, chemical, and physical characteristics and the ability 

of the waterbody to maintain the ecosystems it supports and influences. It is an important measure 

for both ecological and human health. The impacts of OCS Program-related routine operational 

discharges (Chapter 3.1.5.1) on water quality are short term and localized, and are therefore 

considered negligible. The potential impacts from OCS Program-related oil spills on water quality 

after mitigation are also short term and are considered minor. This is because after removal of most 

free product, the residual oil dissipates quickly through dispersion and weathering; however, 

secondary impacts to water quality may occur, such as the introduction of additional hydrocarbon 
2-36 Gulf of Mexico Multisale EIS

into the dissolved phase through the use of dispersants and the sinking of hydrocarbon residuals 

from burning. The impacts from a proposed action are a small addition to the cumulative impacts on 

water quality when compared with inputs from hypoxia, potentially leaking shipwrecks, chemical 

weapon and industrial waste dumpsites, natural oil seeps, and natural turbidity. The incremental 

contribution of the routine activities and accidental events associated with a proposed action to the 

cumulative impacts on water quality is expected to be minor for any of the action alternatives. A full 

analysis of water quality can be found in Chapter 4.2. 

2.4.3 Coastal Habitats

2.4.3.1 Estuarine Systems (Wetlands and Seagrasses/Submerged Vegetation)

The estuarine system is the transition zone between freshwater and marine environments. It 

can consist of many habitats, including wetlands and submerged vegetation. The impacts to these 

habitats from routine activities associated with a proposed action are expected to be negligible due 

to the projected low probability for any new pipeline landfalls (0-1 projected), the minimal contribution 

to the need for maintenance dredging, and the mitigating measures expected to be used to further 

reduce these impacts (e.g., the use of modern techniques such as directional drilling). Overall, 

impacts to estuarine habitats from oil spills associated with activities related to a proposed action 

would be expected to be minor because of the distance of most postlease activities from the coast, 

the expected weathering of spilled oil over that distance, the projected low probability of large spills 

near the coast, the resiliency of wetland vegetation, and the available cleanup techniques. 

Cumulative impacts to estuarine habitats are caused by a variety of factors, including the OCS oiland gas-related and non-OCS oil- and gas-related activities outlined in Chapter 4.3.1 and human 

and natural impacts. Development pressures in the coastal regions of the GOM have been largely 

the result of tourism and residential beach-side development, and this trend is expected to continue. 

Storms will continue to impact the coastal habitats and have differing impacts. The incremental 

contribution of a proposed action to the cumulative impacts on estuarine habitats is expected to be 

negligible to minor depending on the selected alternative. A full analysis of estuarine habitats can 

be found in Chapter 4.3.1. 

2.4.3.2 Coastal Barrier Beaches and Associated Dunes

The coastal barrier beaches and associated dunes are those beaches and dunes that line 

the coast of the northern GOM, including both barrier islands and beaches on the mainland. The 

impacts to coastal barrier beaches and dunes from routine activities associated with a proposed 

action are expected to be negligible due to the minimal number of projected onshore pipelines, the 

minimal contribution to vessel traffic and to the need for maintenance dredging, and the mitigating 

measures that would be used to further reduce these impacts. The greater threat from an oil spill to 

coastal beaches is from a coastal spill as a result of a nearshore vessel accident or pipeline rupture, 

and cleanup activities. Overall, impacts to coastal barrier beaches and dunes from oil spills 

associated with OCS oil- and gas-related activities related to a proposed action would be expected 

to be minor because of the distance of most of the resulting activities from the coast, expected 

weathering of spilled oil, projected low probability of large spills near the coast, and available 
Alternatives Including the Proposed Actions 2-37

cleanup techniques. Cumulative impacts to coastal barrier beaches and dunes are caused by a 

variety of factors, including the OCS oil- and gas-related and non-OCS oil- and gas-related activities 

outlined in Chapter 4.3.2 and other human and natural impacts. Development pressures in the 

coastal regions of the GOM have been largely the result of tourism and residential beach-side 

development, and this trend is expected to continue. Efforts to stabilize the GOM shoreline have 

adversely impacted coastal beach landscapes. Storms will continue to impact the coastal habitats 

and have differing impacts. The incremental contribution of a proposed action to the cumulative 

impacts on estuarine habitats is expected to be negligible to minor depending on the selected 

alternative. A full analysis of coastal barrier beaches and associated dunes can be found in Chapter 

4.3.2. 

2.4.4 Deepwater Benthic Communities

BOEM defines “deepwater benthic communities” as including both chemosynthetic 

communities (chemosynthetic organisms plus seep-associated fauna) and deepwater coral 

communities (deepwater coral plus associated fauna). These communities are typically found in 

water depths of 984 ft (300 m) or deeper throughout the GOM, although deepwater benthic habitats 

are relatively rare compared with ubiquitous soft bottoms.

The OCS oil- and gas-related, impact-producing factors for deepwater benthic communities 

can be grouped into three main categories: (1) bottom-disturbing activities; (2) drilling-related 

sediment and waste discharges; and (3) noncatastrophic oil spills. These impact-producing factors 

have the potential to damage individual deepwater habitats and disrupt associated benthic 

communities if insufficiently distanced or otherwise mitigated. However, impacts from individual 

routine activities and accidental events are usually temporary, highly localized, and expected to 

impact only small numbers of organisms and substrates at a time. Moreover, use of the expected 

site-specific plan reviews/mitigations will distance activities from deepwater benthic communities, 

greatly diminishing the potential effects. Therefore, at the regional, population-level scope of this 

analysis and assuming adherence to all expected regulations and mitigations, impacts from 

reasonably foreseeable routine activities and accidental events are expected to be negligible to 

minor for any of the action alternatives. Proposed OCS oil- and gas-related activities would also 

contribute incrementally to the overall OCS and non-OCS cumulative effects experienced by live 

bottom habitats. The OCS oil- and gas-related cumulative impacts to deepwater benthic 

communities are estimated to be negligible to minor. A full analysis of deepwater benthic 

communities can be found in Chapter 4.4. 

2.4.5 Sargassum and Associated Communities

Sargassum in the GOM is comprised of S. natans and S. fluitans (Lee and Moser, 1998; 

Stoner, 1983; Littler and Littler, 2000) and is characterized by a brushy, highly branched thallus with 

numerous leaf-like blades and berrylike pneumatocysts (Coston-Clements et al., 1991; Lee and 

Moser, 1998; Littler and Littler, 2000). The Sargassum cycle is truly expansive, encompassing most 

of the western Atlantic Ocean and the Gulf of Mexico with the growth, death, and decay of these 

plant and epiphytic communities, which may play a substantial role in the global carbon cycle. 
2-38 Gulf of Mexico Multisale EIS

Several impacting factors can affect Sargassum, including vessel-related operations, oil and gas 

drilling discharges, operational discharges, accidental spills, non-OCS oil- and gas-related vessel 

activity, and coastal water quality. Routine vessel operations and accidental events that occur 

during drilling operations or vessel operations, and oiling due to an oil spill were the impactproducing factors that could be reasonably expected to impact Sargassum populations in the GOM. 

All of these impact-producing factors would result in the death or injury to the Sargassum plants or to 

the organisms that live within or around the plant matrix. However, the unique and transient 

characteristics of the life history of Sargassum and the globally widespread nature of the plants and 

animals that use the plant matrix buffer against impacts at any given location. Impacts to the overall 

population of the Sargassum community are therefore expected to be negligible from either routine 

activities or reasonably foreseeable accidental events for any of the action alternatives. The 

incremental impact of OCS oil- and gas-related activities on the population of Sargassum would be 

negligible and would not result in cumulative impacts to the population. Impacts from changing 

water quality would be much more influential on Sargassum than OCS development and would still 

occur without the presence of OCS oil- and gas-related activities. A full analysis of Sargassum and 

associated communities can be found in Chapter 4.5. 

2.4.6 Live Bottoms

2.4.6.1 Topographic Features

Defined topographic features (Chapter 4.6.1) are a subset of GOM live bottom habitats that 

are large enough to have an especially important ecological role, with specific protections defined in 

the proposed Topographic Features Stipulation. Within the Gulf of Mexico, BOEM has identified 

37 topographic features where some degree of protection from oil and gas development may be 

warranted based on geography and ecology. Of all the possible impact-producing factors, it was 

determined that bottom-disturbing activities associated with drilling, exploration, and vessel 

operations were the only impact-producing factors from routine activities that could be reasonably 

expected to substantially impact topographic features. The impact-producing factors resulting from 

accidental events include bottom-disturbing activities from drilling, exploration, and vessel operations 

as well as the release of sediments and toxins released during drilling. Oil spill-related activities 

were also considered to be a substantial source of potential impact to topographic features.

Adherence to the Topographic Features Stipulation (detailed in Appendix D) would assist in 

preventing most of the potential impacts on topographic feature communities by increasing the 

distance of OCS oil- and gas-related activities from these features. Should this stipulation be 

applied to any future lease sale, as it has been historically, the impacts of a proposed action to 

topographic features from routine activities and accidental events would be negligible. The 

incremental contribution of a proposed action to the cumulative impacts on topographic features is 

expected to be negligible with adherence to the proposed Topographic Features Stipulation. 

Impacts ranging from negligible to moderate may still be expected from non-OCS oil- and gasrelated activities depending on factors such as fishing and pollution; however, the incremental 

impact of the proposed activities should not result in an augmentation of the expected impacts. 

Additionally, because of the areal extent of the 37 topographic features, any localized impacts at one 
Alternatives Including the Proposed Actions 2-39

topographic feature does not preclude that impacts will occur at other topographic features. A full 

analysis of topographic features can be found in Chapter 4.6.1. 

2.4.6.2 Pinnacles and Low-Relief Features

The Pinnacle Trend is an approximately 64 x 16 mi (103 x 26 km) area in water depths of 

about 200-650 ft (60-200 m). It is in the northeastern portion of the CPA at the outer edge of the 

Mississippi-Alabama shelf between the Mississippi River and De Soto Canyon (Figures 2-4 and 

4-16). Outside of the Pinnacle Trend, low-relief, live bottom epibenthic communities occur in 

isolated locations in shallow waters (<984 ft; 300 m) throughout the GOM wherever there is suitable 

hard substrate and other physical conditions (e.g., depth, turbidity, etc.) for development. Hard 

bottom habitats occur throughout the GOM but are relatively rare compared with ubiquitous soft 

bottoms.

The impact-producing factors for pinnacles and low-relief live bottom features can be 

grouped into three main categories: (1) bottom-disturbing activities; (2) drilling-related sediment and 

waste discharges; and (3) oil spills. These impact-producing factors have the potential to damage 

individual deepwater habitats and disrupt associated benthic communities if insufficiently distanced 

or otherwise mitigated. At the broad geographic and temporal scope of this analysis, and assuming 

adherence to all expected lease stipulations and typically applied regulations and mitigations, routine 

activities are expected to have largely short-term localized and temporary effects. Although 

accidental events have the potential to cause severe damage to specific live bottom communities, 

the number of such events is expected to be very small. Therefore, at the regional, population-level 

scope of this analysis, impacts from reasonably foreseeable routine activities and accidental 

activities are expected to be negligible to minor. Proposed OCS oil- and gas-related activities 

would also contribute incrementally to the overall OCS and non-OCS cumulative effects experienced 

by live bottom habitats. The OCS oil- and gas-related cumulative impacts to live bottom 

communities are estimated to be negligible. A full analysis of pinnacles and low-relief features can 

be found in Chapter 4.6.2. 

2.4.7 Fish and Invertebrate Resources

The distribution of fishes and invertebrates vary widely and species may be associated with 

different habitats at various life stages discussed further in Chapter 4.7. The impact-producing 

factors affecting these resources are anthropogenic sound, bottom-disturbing activities, habitat 

modification, and accidental oil spills. The impacts from routine activities, excluding infrastructure 

emplacement, would be expected to be negligible or minor due to short-term localized effects. The 

installation of OCS oil- and gas-related infrastructure constitutes a long-term modification of the local 

habitat and is hypothesized to have resulted over the life of the program in moderate changes in the 

distribution of some species. Although this effect is not necessarily adverse and infrastructure is 

expected to be decommissioned and sites restored to natural habitat, the cumulative impact over the 

life of the OCS Program is spatiotemporally extensive. Accidental spills have been historically lowprobability events and are typically small in size. The expected impact to fishes and invertebrate 

resources from accidental oil spills is negligible. Commercial and recreational fishing are expected 
2-40 Gulf of Mexico Multisale EIS

to have the greatest direct effect on fishes and invertebrate resources, resulting in impact levels 

ranging from negligible for most species to potentially moderate for some targeted species (e.g., 

hogfish spp., gray triggerfish, and greater amber jack [Seriola dumerili]). The analysis of OCS oiland gas-related and non-OCS oil- and gas-related routine activities, accidental events, and 

cumulative impacts indicates the overall impact to fishes and invertebrate resources would range 

from negligible to moderate for different species for any of the action alternatives. A full analysis of

fish and invertebrate resources can be found in Chapter 4.7. 

2.4.8 Birds

The affected birds include both terrestrial songbirds and many groups of waterbirds. Routine 

impacts to coastal, marine, and migratory birds that were considered include routine discharges and 

wastes, noise, platform severance with explosives (barotrauma), geophysical surveys with airguns, 

platform presence and lighting, construction of OCS oil- and gas-related onshore facilities, and 

pipeline landfalls. The impacts to birds from OCS oil-and gas-related routine activities are similar 

wherever they may occur in the GOM, and all are considered negligible to minor. Negligible 

impacts would be little to no impacts that are measured or measurable for a population. No mortality 

of a flock or large population would occur, and no overall disturbance-causing changes in behavioral 

patterns would be expected. Minor impacts would occur when one of the two following conditions 

are met: (1) flocks or large populations of birds would experience stimuli or impact-producing factors 

and would be disturbed or otherwise affected overall, resulting in acute behavioral changes; 

however, these impacts would be short-term and reversible; and (2) one or more incidents where 

one or more individuals experience injury or mortality may occur, but with no measured or 

measurable impact on a large population. Accidental impacts to birds are caused by oil spills, spill 

cleanup, and emergency air emissions. Seabirds may not always experience the greatest impacts 

from a spill but may take longer for populations to recover because of their unique population 

ecology (demography). Some species of seabirds can have a clutch size of just one egg, and they 

have relatively long life spans and often have delayed age at first breeding. Impacts for overall 

accidental events would therefore be expected to be moderate. The overall impacts from routine 

and accidental activities resulting from a proposed action are considered moderate, but only 

because of the impacts of a large oil spill (≥1,000 bbl). However, other seabirds such as gulls have 

larger clutches (laughing gulls usually have three eggs/clutch except in the tropics) and may recover 

quite quickly. This conclusion is based on the incremental contribution of a proposed action to the 

cumulative OCS oil- and gas-related and non-OCS oil- and gas-related impacts. A full analysis of

coastal and migratory birds can be found in Chapter 4.8. 

2.4.9 Protected Species

2.4.9.1 Marine Mammals

The Gulf of Mexico marine mammal community is diverse and distributed throughout the 

GOM, with the greatest abundances and diversity of species inhabiting oceanic and OCS waters. 

The major potential impact-producing factors affecting marine mammals in the GOM as a result of 

cumulative past, present, and reasonably foreseeable OCS energy-related activities are 
Alternatives Including the Proposed Actions 2-41

decommissioning activities, operational discharges, G&G activities, noise, transportation, marine 

debris, and accidental oil-spill and spill-response activities. Accidental events that involve large 

spills, particularly those continuing to flow fresh hydrocarbons into oceanic and/or outer shelf waters 

for extended periods (i.e., days, weeks, or months), pose an increased likelihood of impacting 

marine mammal populations inhabiting GOM waters. While accidental events have the potential to 

impact marine mammal species, the number of such events is expected to be very small.

At the regional, population-level scope of this analysis, impacts from reasonably foreseeable 

routine activities and accidental events are expected to be negligible to moderate for any of the 

action alternatives. Proposed OCS oil- and gas-related activities would also contribute incrementally 

to the overall OCS and non-OCS cumulative effects experienced by marine mammal populations. 

The incremental contribution of a proposed action to the cumulative impacts to marine mammal 

populations, depending upon the affected species and their respective population estimate, even 

when taking into consideration the potential impacts of the Deepwater Horizon explosion, oil spill, 

and response; non-OCS oil- or gas-related factors; and the minimization of the OCS oil- or gasrelated impacts through lease stipulations and regulations, would be expected to be negligible. A 

full analysis of marine mammals can be found in Chapter 4.9.1. 

2.4.9.2 Sea Turtles

Five sea turtle species have been listed and are present throughout the northern GOM; 

however, only Kemp’s ridley and loggerheads commonly nest on beaches in the GOM. Because of 

expected mitigations (e.g., BOEM and BSEE proposed compliance with NTLs under the proposed 

Protected Species Stipulation and conditions of approval on postlease activities), routine activities 

(e.g., noise or transportation) and accidental events (e.g., oil spills) related to a proposed action are 

not expected to have long- term adverse effects on the size and productivity of any sea turtle 

species or populations in the northern GOM. Lethal effects could occur from chance collisions with 

OCS oil- and gas-related service vessels or ingestion of accidentally released plastic materials from 

OCS oil- and gas-related vessels and facilities. However, there have been no reports to date on 

such incidences. Most routine activities and accidental events as a result of a proposed action are 

therefore expected to have negligible to moderate impacts. For example, a minor impact might be 

a behavioral change in response to noise while a moderate impact might be a spill contacting an 

individual and causing injury or mortality.

Historically, intense harvesting of eggs, loss of suitable nesting beaches, and fishery-related 

mortality have led to the rapid decline of sea turtle populations. Anthropogenic actions continue to 

pose the greatest threat to sea turtles since their listing under the ESA, as well as different natural 

threats including climate change and natural disasters. Cumulative impacts to sea turtles would be 

expected to be negligible as a result of a proposed action. Population-level impacts are not 

anticipated. A full analysis of sea turtles can be found in Chapter 4.9.2. 
2-42 Gulf of Mexico Multisale EIS

2.4.9.3 Beach Mice

The four subspecies of beach mouse (Peromyscus polionotus ssp.) are small coastal 

rodents that are only found along beaches in parts of Alabama and northwest Florida. Beach mice 

rely on dune systems as favorable habitat for foraging and maintaining burrows. Due to the distance 

between beach mouse habitat and OCS oil- and gas-related activities, routine impacts are not likely 

to affect beach mouse habitat except under very limited situations. Pipeline emplacement or 

construction, for example, could cause temporary degradation of beach mouse habitat; however, 

these activities are not expected to occur in areas of designated critical habitat. Accidental oil spills 

and associated spill-response efforts are not likely to impact beach mice or their critical habitat 

because the species live above the intertidal zone where contact is less likely. Habitat loss from 

non-OCS oil- and gas-related activities (e.g., beachfront development) and predation have the 

greatest impacts to beach mice. The overall analyses of impact-producing factors associated with 

the routine activities, accidental events, and cumulative impacts of OCS oil- and gas-related and 

non-OCS oil- and gas-related activities on beach mice concluded that impacts from a proposed 

action would be negligible for any of the action alternatives. A full analysis of beach mice can be 

found in Chapter 4.9.3. 

2.4.9.4 Protected Birds

Protected birds are species or subspecies listed under the ESA by the FWS as threatened or 

endangered due to the decrease in their population sizes or loss of habitat; therefore, a proposed 

action could have a greater impact. BOEM is undergoing consultation with the FWS to minimize the 

potential impacts to ESA-listed species. Impacts from routine activities, which include discharges 

and wastes affecting air and water quality, noise, and possibly artificial lighting, would be negligible

to protected birds. The listed bird species considered are typically coastal birds and would not be 

exposed to much of the oil and gas activities. Waste discharges to air or water produced as a result 

of routine activities are regulated by the USEPA and BOEM and are subject to limits to reduce 

potential impacts; therefore, due to precautionary requirements and monitoring, the impacts to 

protected birds would be negligible for any of the action alternatives. The major impact-producing 

factors resulting from accidental events associated with a proposed action that may affect protected 

birds include accidental oil spills and response efforts and marine debris. In the case of an 

accidental oil spill, impacts would be negligible to moderate depending on the magnitude and 

spatiotemporal proximity of such an event. Major impacts could occur if a large oil spill occurred with 

direct contact to a protected bird species or if the habitat became contaminated resulting in mortality 

of a listed species. Marine debris produced by OCS oil- and gas-related activities as a result of 

accidental disposal into the water may affect protected birds by entanglement or ingestion. Due to 

the regulations prohibiting the intentional disposal of items, impacts would be expected to be 

negligible, however, impacts may scale up to moderate if the accidental release of marine debris 

caused mortality of a listed bird. Overall, BOEM would expect negligible to moderate impacts to 

protected birds considering routine, accidental and cumulative impacts for any of the action 

alternatives. A full analysis of protected birds can be found in Chapter 4.9.4. 
Alternatives Including the Proposed Actions 2-43

2.4.9.5 Protected Corals

Elkhorn, staghorn, boulder star, lobed star, and mountainous corals are listed by the NMFS 

as threatened due to the decrease in their population sizes; therefore, impacts from a proposed 

action could have a higher level than realized by other coral species. BOEM understands this and is 

undergoing consultation for these species to minimize the potential impacts. Though the listed 

species are protected, they would have the same impacts from a proposed action as other coral 

species. Without effective mitigations, the proposed action could directly impact coral habitat within 

the GOM. Assuming adherence to all expected lease stipulations and other postlease, protective 

restrictions and mitigations, the routine activities related to a proposed action are expected to have 

mostly short-term localized and temporary effects because the site-specific survey information and 

distancing requirements described in NTL 2009-G39 will allow BOEM to identify and protect live 

bottom features (which protected corals may inhabit) from harm by proposed OCS oil- and gasrelated activities during postlease reviews. While accidental events have the potential to cause 

severe damage to specific coral communities, the number of such events is expected to be small. 

Further, many of the protected corals occur in the Flower Garden Banks National Marine Sanctuary, 

which, under the current boundaries, is not proposed for future leasing under any of the alternatives 

in this Multisale EIS. Therefore, the incremental contribution of activities resulting from a proposed 

action to the overall cumulative impacts to protected corals is expected to be negligible to minor for 

any of the action alternatives. Proposed OCS oil- and gas-related activities would contribute 

incrementally to the overall OCS and non-OCS cumulative impacts experienced by corals. A full 

analysis of protected corals can be found in Chapter 4.9.5. 

2.4.10 Commercial Fisheries

A proposed action could affect commercial fisheries by affecting fish populations or by 

affecting the socioeconomic aspects of commercial fishing. The impacts of a proposed action on 

fish populations are presented in Chapter 4.7. Routine activities such as seismic surveys, drilling 

activities, and service-vessel traffic can cause space-use conflicts with fishermen. Structure 

emplacement could have positive or negative impacts, depending on the location and species. For 

example, structure emplacement prevents trawling in the associated area and, thus, could impact 

the shrimp fishery. On the other hand, production platforms can facilitate fishing for reef fish such as 

red snapper and groupers. Accidental events, such as oil spills, could cause fishing closures and 

have other impacts on the supply and demand for seafood. However, accidental events that could 

arise from a proposed action would likely be small and localized. A proposed action would be 

relatively small when compared with the overall OCS Program, State oil and gas activities, overall 

vessel traffic, hurricanes, economic factors, Federal and State fisheries management strategies, and 

other non-OCS oil- and gas-related factors. Therefore, the incremental contribution of a proposed 

action to the cumulative impacts to commercial fisheries would range from beneficial to minor for 

any of the action alternatives. The exact impacts would depend on the locations of activities, the 

species affected, the intensity of commercial fishing activity in the affected area, and the 

substitutability of any lost fishing access. Alternative E would prevent these impacts from occurring, 

although commercial fisheries would still be subject to the impacts from the OCS Program, as well 
2-44 Gulf of Mexico Multisale EIS

as the impacts from non-OCS sources. A full analysis of commercial fisheries can be found in 

Chapter 4.10. 

2.4.11 Recreational Fishing

The Gulf’s extensive estuarine habitats (Chapter 4.3.1), live bottom habitats (Chapter 4.6), 

and artificial substrates (including artificial reefs, shipwrecks, and oil and gas platforms) support 

several valuable recreational fisheries. Alternatives A-D can affect recreational fishing by affecting 

fish populations or by affecting the socioeconomic aspects of recreational fishing. The impacts of 

Alternatives A-D on fish populations are presented in Chapter 4.7. Vessel traffic can cause spaceuse conflicts with anglers. Structure emplacement generally enhances recreational fishing, although 

this positive effect will be offset during decommissioning unless a structure were maintained as an 

artificial reef. Accidental events, such as oil spills, can cause fishing closures and can affect the 

aesthetics of fishing in an area. However, accidental events that could arise would likely be small 

and localized. Alternatives A-D should also be viewed in light of overall trends in OCS platform 

decommissioning, State oil and gas activities, overall vessel traffic, hurricanes, economic factors, 

and Federal and State fisheries management strategies. The incremental impacts of Alternatives 

A-D on recreational fisheries are expected to be negligible to minor. A full analysis of recreational 

fishing can be found in Chapter 4.9.11. 

2.4.12 Recreational Resources

Alternatives A-D would contribute to the negligible to minor aesthetic impacts and space-use 

conflicts that arise due to the broader OCS Program. These conflicts arise due to marine debris, the 

visibility of platforms, and vessel traffic. Structure emplacements can have positive impacts on 

recreational fishing and diving because platforms often act as artificial reefs. Oil spills can negatively 

affect beaches and other coastal recreational resources. Alternatives A-D should also be viewed in 

light of economic trends, as well as various non-OCS oil- and gas-related factors that can cause 

space-use conflicts and aesthetic impacts, such as commercial and military activities. Because of 

the relatively small contribution of any given lease sale under any of the proposed action alternatives 

to the overall OCS Program, in addition to other non-OCS oil- and gas-related activities, the various 

impacts are expected to be beneficial to minor. A full analysis of recreational resources can be 

found in Chapter 4.12. 

2.4.13 Archaeological Resources

Archaeological resources are any material remains of human life or activities that are at least 

50 years of age and that are capable of providing scientific or humanistic understanding of past 

human behavior, cultural adaptation, and related topics through the application of scientific or 

scholarly techniques, such as controlled observation, contextual measurement, controlled collection, 

analysis, interpretation, and explanation (30 CFR § 250.105). Archaeological resources are 

primarily impacted by any activity that directly disturbs or has the potential to disturb the seafloor. 

For the OCS Program, this includes the placement of drilling rigs and production systems on the 

seafloor; pile driving associated with platform emplacement; pipeline placement and installation; the 
Alternatives Including the Proposed Actions 2-45

use of seismic receiver nodes and cables; the dredging of new channels, as well as maintenance 

dredging of existing channels; anchoring activities; post-decommissioning activities including 

trawling clearance; and the masking of archaeological resources from industry-related infrastructure 

and debris.

Regardless of which planning area a proposed lease sale is held, the greatest potential 

impact to an archaeological resource as a result of a proposed action under any of the action 

alternatives is site-specific and would result from direct contact between an offshore activity or 

accidental event and a site. Archaeological surveys, where required prior to an operator beginning 

OCS oil- and gas-related activities on a lease, are expected to be effective at identifying possible 

archaeological sites. A proposed action’s postlease activities, including the drilling of wells and 

installation of platforms, installation of pipelines, anchoring, and removal of platforms and other 

structures installed on the seafloor and site clearance activities, as well as accidental events such as 

loss of debris, may result in negligible to major impacts to archaeological sites.

There is no acceptable threshold of negative cumulative impacts to archaeological sites. 

Identification, evaluation, and avoidance or mitigation of archeological resources is expected to 

result in negligible, long-term cumulative impacts to archeological resources; however, if an 

archaeological site were to be impacted, impacts may range from negligible to major. A full 

analysis of archaeological resources can be found in Chapter 4.13. 

2.4.14 Human Resources and Land Use (Including Environmental Justice)

2.4.14.1 Land Use and Coastal Infrastructure

Oil and gas exploration, production, and development activities on the OCS are supported by 

an expansive onshore network of coastal infrastructure that includes hundreds of large and small 

companies. Because OCS oil- and gas-related activities are supported by this long-lived, expansive 

onshore network, a proposed action is not expected to produce any major impacts to land use and 

coastal infrastructure. The impacts of reasonably foreseeable accidental events such as oil spills, 

chemical and drilling fluid spills, and vessel collisions are not likely to last long enough to adversely 

affect overall land use or coastal infrastructure in the analysis area. In the cumulative analysis, 

activities relating to all past, present, and future OCS oil- and gas-related activities and State oil and 

gas production are expected to minimally affect the current land use of the analysis area because 

most subareas have strong industrial bases and designated industrial parks. Non-OCS oil- and gasrelated factors contribute substantially to the cumulative impacts on land use and coastal 

infrastructure, while there is only a small incremental contribution of a proposed lease sale. For any 

of the action alternatives, the cumulative impacts on land use and coastal infrastructure could range 

from negligible to major depending on the specifics of each situation, whether the impacts are 

measurable, how long the impacts would last, and the size of the affected geographic area as 

defined in Chapter 4.14.1. A full analysis of land use and coastal infrastructure can be found in 

Chapter 4.14.1. 
2-46 Gulf of Mexico Multisale EIS

2.4.14.2 Economic Factors

A proposed action would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Some of these impacts would 

be concentrated along the Gulf Coast, while others would be widely distributed. A proposed action 

would also lead to negative economic impacts arising from accidental events and other sources. 

There would be some differences in economic impacts among Alternatives A-D, corresponding to 

the differences in the scales and distributions of likely activities. Alternatives A-D should be viewed 

in light of the OCS Program, as well the numerous forces that can affect energy markets and the 

overall economy. Most of the incremental economic impacts of a proposed action are forecast to be 

positive, although there would be some negligible to minor adverse impacts due to oil spills and to 

the effects on industries that compete with the offshore oil and gas industry for resources. A full 

analysis of economic factors can be found in Chapter 4.14.2. 

2.4.14.3 Social Factors (Including Environmental Justice)

Potential social impacts resulting from a proposed action would occur within the larger 

socioeconomic context of the GOM region. The affected environment of the analysis area is quite 

large geographically and in terms of population (133 counties and parishes with over 22.7 million 

residents). The impacts from routine activities related to a proposed action are expected to be 

negligible, widely distributed, and to have little impact because of the existing extensive and 

widespread support system for the petroleum industry and its associated labor force. Outside of a 

low-probability catastrophic oil spill, which is not reasonably foreseeable and not part of a proposed 

action, any potential accidental events are not likely to be of sufficient scale or duration to have 

adverse and disproportionate long-term impacts for people and communities in the analysis area. 

Non-OCS oil- and gas-related factors, which include all human activities, natural events, and 

processes, actually contribute more to cumulative impacts than do factors related to OCS oil- and 

gas-related activities alone. When considered with existing and projected routine activities and 

cumulative impacts and the potential accidental events, the incremental contributions of a proposed 

action and the OCS Program to social impacts are expected to be minor for any of the action 

alternatives. The oil and gas industry in the GOM region is expansive and long-lived over several 

decades with substantial infrastructure in place to support both onshore and offshore activities. 

BOEM’s scenario estimates call for 0-1 new gas processing plant and 0-1 new pipeline landfall over 

the 50-year life of a single proposed action. Impacts to GOM populations from a proposed action 

would be immeasurable for environmental justice since these low-income and minority communities 

are located onshore, distant from Federal OCS oil- and gas-related activities. Also, since these 

vulnerable populations are located within the larger context of onshore and State-regulated 

nearshore oil and gas activities that are connected to downstream infrastructure over which BOEM 

has no regulatory authority, BOEM has determined that a proposed action would not produce 

environmental justice impacts in the GOM region. A full analysis of social factors and an 

environmental justice determination can be found in Chapter 4.14.3. 
CHAPTER 3 

IMPACT-PRODUCING FACTORS AND SCENARIO

Impact-Producing Factors and Scenario 3-3 

What’s in This Chapter

BOEM develops scenarios that describe OCS oil- and gas-related routine activities and 

accidental events from a single lease sale, the OCS oil and gas cumulative activities of multiple 

lease sales, and the non-OCS oil- and gas-related activities and/or events.

• Routine activities for a single lease sale include the following:

− Exploration and Delineation – geological and geophysical surveys, and drilling 

exploration and delineation wells.

− Offshore Development and Production – drilling production wells, infrastructure 

emplacement, and work-overs and abandonment of wells.

− Transport – resource transportation (e.g., pipelines and tankers) as well as 

service transportation (e.g., service vessels and helicopters).

− Discharges and Wastes – includes operational wastes produced by facilities 

and vessels, and the disposal of wastes.

− Decommissioning and Removal.

− Coastal Infrastructure – information on all the types of infrastructure that 

supports the offshore oil and gas industry (e.g., construction, transport, and 

processing facilities).

− Air Emissions.

− Noise – the types of noise routinely produced during a lease.

− New and Unusual Technology – the technologies that have evolved to meet 

the technical, environmental, and economic challenges of deepwater 

development.

• Accidental events for a single lease sale could include the following (analyses based on 

historical data and trends): 

− Oil Spills – information on coastal and offshore spills.

− Losses of Well Control – the process of a loss of well control event.

− Accidental Air Emissions – instances that might result in accidental air 

emissions, including hydrogen sulfide (H2S).

− Pipeline Failures – instances that might result in a pipeline failure (e.g., 

hurricanes).

− Vessel and Helicopter Collisions – instances that might result in a vessel or 

helicopter collision and the history of these incidences.

− Chemical and Drilling-Fluid Spills – instances that might result in a chemical or 

drilling-fluid spill.

− Spill Response – the spill-response requirements and initiatives, offshore 

response, containment, and cleanup technology, and the activities involved in 

an onshore response and cleanup.

• Cumulative activities include the following:

− Cumulative OCS Oil and Gas Program – all activities (i.e., the routine activities 

projected to occur and the accidental events that could occur, as listed above) from 

past, proposed, and future lease sales.

− Non-OCS Oil- and Gas-Related Activities – impact-producing factors that are 

considered in a broader context and that take into account the broad range of other 

activities taking place within the proposed lease sale area.

3 IMPACT-PRODUCING FACTORS AND SCENARIO

This chapter describes the offshore infrastructure and activities (impact-producing factors) 

associated with Alternative A or a regionwide proposed action (i.e., a typical lease sale that would 

result from a proposed action), which would encompass all acreage available for lease within the 
3-4 Gulf of Mexico Multisale EIS

WPA, CPA, and EPA (not under moratorium) that could potentially affect the biological, physical, and 

socioeconomic resources of the Gulf of Mexico. This chapter also describes the offshore 

infrastructure and activities associated with two alternatives that would offer proposed lease sales by 

individual planning area, which would consist of a single lease sale for all acreage available for lease 

and not under moratorium either within the CPA and EPA combined (Alternative B) or the WPA 

(Alternative C). Under Alternative D, the number of blocks that would become unavailable for lease 

represents only a small percentage (<4%) of the total number of blocks to be offered under 

Alternative A, B, or C. Therefore, Alternative D could reduce offshore infrastructure and activities by 

up to 4 percent when chosen in conjunction with Alternative A, B, or C. However, it is also possible 

that Alternative D would only shift the location of offshore infrastructure and activities farther from 

sensitive topographic zones and not lead to a reduction in offshore infrastructure and activities. 

Refer to Chapter 2.2.2.4 for more information on Alternative D. In addition, Chapter 3.3.1 describes 

the Cumulative OCS Oil and Gas Program scenario or activity resulting from past and future lease 

sales in the GOM that could potentially affect the biological, physical, and socioeconomic resources 

of the GOM within the WPA, CPA, and EPA.

A scenario describes the offshore activities that could occur for a single lease sale under 

each alternative. BOEM’s Gulf of Mexico OCS Region developed these scenarios to support the 

detailed analyses of the proposed lease sales’ potential impacts whether regionwide or for individual 

planning areas, as defined in the alternatives in Chapter 2.2.2. Each scenario is a hypothetical 

framework of assumptions based on estimated amounts, timing, and general locations of OCS 

exploration, development, and production for offshore and onshore activities and facilities. The 

scenario for each alternative is defined as a set of ranges for resource estimates, projected 

exploration and development activities, and impact-producing factors.

The scenarios do not predict future oil and gas activities with absolute certainty, even though 

they were formulated using historical information and current trends in the oil and gas industry. 

These scenarios are only approximate since future factors such as the economic climate, the 

availability of support facilities, and pipeline capacities are all unknown. The scenarios used in this 

Multisale EIS represent the best assumptions and estimates of a set of future conditions that are 

considered reasonably foreseeable and suitable for presale impact analyses. The development 

scenarios do not represent a BOEM recommendation, preference, or endorsement of any level of 

leasing or offshore operations or of the types, numbers, and/or locations of any onshore operations 

or facilities.

BOEM projects that the overwhelming majority of the oil and natural gas fields discovered as 

a result of each alternative would reach the end of their economic life within a time span of 50 years 

following a lease sale. Therefore, activity levels are not projected beyond 50 years for this Multisale 

EIS. Although unusual cases exist where activity on a lease may continue beyond 50 years, our 

forecasts indicate that the significant activities associated with exploration, development, production, 

and abandonment of leases in the GOM occur well within the 50-year analysis period. 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. The forecasts used to develop 
Impact-Producing Factors and Scenario 3-5 

the proposed actions and OCS oil and gas scenarios are based on resource estimates developed by 

BOEM in 2015, published data and information, and historical activity and discovery trends in the 

GOM.

BOEM uses a series of spreadsheet-based data analyses tools to develop the forecasts of 

oil and gas exploration, discovery, development, and production activity for each alternative scenario 

presented in this Multisale EIS. The analyses incorporate all relevant historical activity and 

infrastructure data, and the 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 the analysis methodology, with adjustments and refinements based 

on recent activity levels, adequately project Gulf of Mexico OCS oil and gas-related activities in both 

the short term and the long term for the Multisale EIS analyses.

Each alternative single sale scenario is based on the following factors: 

• recent trends in the amount and location of leasing, exploration, and 

development activity;

• 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; 

• oil and gas technologies and the economic considerations and environmental 

constraints of these technologies.

The Five-Year Program currently establishes one lease sale the first and last calendar year 

of the 2017-2022 Five-Year Program, and two lease sales per calendar year during the 3 other 

years. Historically, these lease sales have alternated between one single CPA lease sale 

(Alternative B) and one single WPA lease sale (Alternative C) per year. There were only two EPA 

lease sales in the previous Five-Year Program (2012-2017). However, Alternative A, which covers 

all planning areas in one regionwide lease sale, has not previously been analyzed and historic trend 

data are limited. As a result, Alternative A covers a broad range of offshore infrastructure and 

activities. BOEM projects that a lease sale could potentially be as large as the highest historic CPA 

lease sale and the highest historic WPA lease sale combined, or it could be as small as the smallest 

WPA lease sale. For a proposed action under Alternative A, the majority of the activity is assumed 

to remain in the CPA.

When analyzing hydrocarbon resources by planning area across the GOM, regardless of the 

alternative, the majority of oil and gas resources are located within the boundaries of the CPA. 
3-6 Gulf of Mexico Multisale EIS

Therefore, for a proposed action under Alternative A, which would encompass all acreage available 

for lease within the WPA, CPA, and EPA, the majority of the activity would still be located in the 

CPA. An analysis of the scenario forecast for Alternative A suggests that a maximum of 88 percent 

of the oil production and associated activity and 83 percent of the gas production and associated 

activity is forecasted to occur within the CPA/EPA. A maximum of 13 percent of the oil production 

and associated activity and 19 percent of the gas production and associated activity from 

Alternative A is forecasted to occur within the WPA.

The average activity level associated with a proposed lease sale is expected to vary based 

on a number of factors, including the price of oil, resource potential, cost of development, and 

resource availability (e.g., drill rig availability). The scenario information presented throughout this 

text is expressed as a range from a low oil-price case scenario to a high oil-price case scenario. 

Because the low and high oil-price case scenarios are used to create the range in scenario oil and 

gas activity, this may result in ranges of percentages appearing reversed (larger number first) as the 

proportion of activity levels may shift between the scenarios. For example, the larger proportion of a 

given activity or impact-producing factor may occur in the low oil-price case scenario, thus creating a 

range with a larger number in the low oil-price case scenario (e.g., 40-6%). This format is used 

because this scenario range represents that 40 percent of wells would be drilled on the continental 

shelf in the low case and 6 percent in the high case, and though this is technically 6-40 percent of 

the wells, the placement of the 40-6 percent more accurately reflects the low and high oil-price case 

scenarios.

Finally, it is important to note that a single lease sale, no matter which alternative is selected, 

would represent only a small proportion and small contribution to past, present, and future activity as 

a result of the overall forecasted Cumulative OCS Oil and Gas Program scenario or activity 

forecasted to occur between 2017 and 2086. 

Single Lease Sale 

(2017-2066)

Percent of Production of a Single Lease Sale in Relation to

Cumulative Production 

Regionwide 

(2017-2086)

Cumulative Production 

in the CPA/EPA 

(2017-2086)

Cumulative Production 

in the WPA 

(2017-2086)

Alternative A 1.2-4.2% – –

Alternative B 1.0-3.6% 1.2-4.4% –

Alternative C 0.2-0.6% – 1.2-3.5%

Note: Alternative D could reduce production values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

Specific projections for activities associated with a single lease sale under each alternative 

are discussed in the following scenario sections.
Impact-Producing Factors and Scenario 3-7 

3.1 IMPACT-PRODUCING FACTORS AND SCENARIO—ROUTINE OPERATIONS

3.1.1 Resource Estimates and Timetables

A single lease sale scenario was developed for each alternative and is used to assess the 

potential impacts of a proposed lease sale within the geographic ranges of each alternative. The 

resource estimates for each alternative are based on two factors: (1) the conditional estimates of 

undiscovered, unleased, conventionally recoverable oil and gas resources in the proposed lease 

sale areas; and (2) the estimates of the portion or percentage of these resources assumed to be 

leased, discovered, developed, and produced as a result of a proposed action and each alternative. 

Due to the inherent uncertainties associated with an assessment of undiscovered resources, 

probabilistic techniques were employed and the results are 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 each alternative are 

based upon logical sequences of events that incorporate past experience, current conditions, and 

foreseeable development strategies. BOEM used historical databases and information derived from 

oil and gas exploration and development activities to develop each scenario. The undiscovered, 

unleased, conventionally recoverable resource estimates for each alternative are expressed as 

ranges from low to high. This range provides a reasonable expectation of oil and gas production 

anticipated from a single lease sale held as a result of each alternative based on an actual range of 

historic observations.

Table 3-1 presents the projected oil and gas production for a single lease sale under each 

alternative and for the Cumulative OCS Oil and Gas Program (2017-2086). As stated above, the 

number of blocks that would become unavailable for lease under Alternative D represents only a 

small percentage (<4%) of the total number of blocks to be offered under Alternative A, B, or C. 

Therefore, Alternative D could reduce offshore infrastructure and activities by up to 4 percent when 

chosen in conjunction with Alternative A, B, or C. However, it is also possible that Alternative D 

would only shift the location of offshore infrastructure and activities farther from sensitive topographic 

zones and not lead to a reduction in offshore infrastructure and activities. Refer to Chapter 2.2.2.4

for more information on Alternative D. To analyze impact-producing factors for a proposed action 

and each alternative, the geographic ranges of each alternative were 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. The major impact-producing factors of a single lease sale (including the 

number of exploration and delineation wells, production platforms, and development wells) projected 

to develop and produce the estimated oil and gas resources for Alternatives A, B, and C are given in 

Table 3-2. This table shows the distribution of these factors by offshore subareas for each

alternative. Table 3-2 also includes estimates of the major impact-producing factors related to the 

projected levels of exploration, development, and production activity.
3-8 Gulf of Mexico Multisale EIS

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

Reserve/Resource 

Production

Lease Sale

(2017-2066)

OCS Cumulative

(2017-2086)

Alternative A: Regionwide OCS Lease Sale

Oil (BBO) 0.211-1.118 15.482-25.806

Gas (Tcf) 0.547-4.424 57.875-108.513

Alternative B: Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area (or 

the CPA/EPA Portion of the Proposed Lease Sale Area)

Oil (BBO) 0.185-0.970 13.707-22.152

Gas (Tcf) 0.441-3.672 46.328-84.009

Alternative C: Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale 

Area (or the WPA Portion of the Proposed Lease Sale Area)

Oil (BBO) 0.026-0.148 1.775-3.654

Gas (Tcf) 0.106-0.752 11.547-24.504

BBO = billion barrels of oil.

Tcf = trillion cubic feet.

Figure 3-1. Offshore Subareas in the Gulf of Mexico.
Impact-Producing Factors and Scenario 3-9 

Table 3-2. Offshore Scenario Activities Related to a Single Lease Sale for Alternative A, B, or C from

2017 through 2066.

Activity Alternative1

Offshore Subareas (m)2

Totals3

0-60 60-200 200-800 800-

1,600 

1,600-

2,400 >2,400

Exploration 

and 

Delineation 

Wells

A 24-634 8-300 5-11 6-15 5-8 5-16 53-984

B 20-570 5-293 2-8 2-10 2-2 2-10 33-893

C 4-64 2-7 2-3 3-5 3-6 3-6 17-91

Development 

and 

Production 

Wells4

A Total 14-326 7-220 7-95 13-51 10-37 10-38 61-767

B Total 10-282 4-211 4-78 10-35 9-31 9-34 46-671

C Total 4-44 4-9 4-17 4-16 3-6 3-4 22-96

A Oil 1-35 0-23 3-46 6-22 5-19 4-19 19-164

B Oil 1-32 0-23 2-38 5-18 4-16 4-17 16-144

C Oil 0-5 0-1 2-9 1-5 1-4 1-3 5-27

A Gas 1-35 0-23 3-46 6-22 5-19 4-19 19-164

B Gas 5-169 2-120 0-17 1-7 1-6 1-7 10-326

C Gas 2-27 2-6 0-4 1-7 0-1 0-1 5-46

Installed 

Production 

Structures

A 8-183 4-85 1-4 1-3 1-2 1-3 16-280

B 7-158 3-81 1-3 1-2 1 1-2 14-247

C 3-25 2-4 1 1 1 1 9-33

Production 

Structures 

Removed 

Using 

Explosives

A 6-130 3-63 0 0 0 0 9-193

B 5-112 2-60 0 0 0 0 7-172

C 2-18 2-3 0 0 0 0 4-21

Total 

Production 

Structures 

Removed

A 8-183 4-85 1-4 1-3 1-2 1-3 16-280

B 7-158 3-81 1-3 1-2 1 1-2 14-247

C 3-25 2-4 1 1 1 1 9-33

Length of 

Installed 

Pipelines 

(km)5

A 59-527 53-417 53-327 78-358 59-275 53-240 355-2,144

B 40-395 34-336 33-240 55-233 50-227 42-210 254-1,641

C 20-132 20-81 20-88 24-125 10-48 11-31 105-505

ServiceVessel Trips 

(1,000’s round 

trips)

A 9-265 4-126 6-51 7-38 7-26 7-36 43-541

B 8-229 3-120 6-39 6-26 6-15 6-25 38-452

C 3-36 2-6 6-13 6-13 6-12 6-11 30-89

Helicopter 

Operations 

(1,000’s round 

trips)

A 52-2,131 34-1,409 8-71 8-53 8-36 8-53 122-3,750

B 43-1,848 26-1,426 8-53 8-36 8-18 8-36 105-3,415

C 17-299 17-71 8-18 8-18 8-18 8-18 70-440

1 Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 4 percent. Refer to 

Chapter 2.2.2.4 for more information. Alternative A would a regionwide lease sale, Alternative B would be the 

CPA/EPA portions of the lease sale area, and Alternative C would be the WPA portion of the lease sale area. 2 Refer to Figure 3-1. 3 Subareas totals may not add up to the planning area total because of rounding. 4 Development and Production Wells includes some exploration wells that were re-entered and completed. These 

wells were removed from the Exploration and Delineation well count. 5

 Projected length of pipelines does not include length in State waters.
3-10 Gulf of Mexico Multisale EIS

3.1.2 Exploration and Delineation

The timeline for exploration and delineation activities during the life of a “typical” lease are 

shown in Figure 3-2. A lease may range in length depending on hydrocarbon reserve production on 

the lease.

Figure 3-2. Typical Exploration and Production Timeline for Offshore Oil and Gas Drilling.

3.1.2.1 Geological and Geophysical Surveys

Airgun Surveys

Shallow-penetration airgun (HRG airgun) seismic surveys image shallow depths, typically 

1,000 m (3,280 ft) or less below the seafloor to produce high-resolution images. Shallow-penetration 

surveys, also commonly known as shallow hazard surveys, are conducted to investigate the shallow 

subsurface for geohazards and soil conditions and to identify potential benthic biological 
Impact-Producing Factors and Scenario 3-11

communities (or habitats) and archaeological resources. The shallow hazards survey is also used to 

identify and map geologic features in the vicinity of proposed wells, platforms, anchors and anchor 

chains, mounds or knolls, acoustic void zones, gas- or oil-charged sediments, or seeps associated 

with surface faulting that may be indicative of ocean-bottom chemosynthetic communities.

Since 1987, operators have reported shallow waterflow events to BOEM and its 

predecessors. These events are a phenomenon encountered in water depths exceeding 600 ft 

(183 m). Reported waterflows are between a few hundred feet to more than 4,000 ft (1,219 m) 

below the seafloor. Water flowing up and around the well casing and annulus may deposit sand or 

silt on the seafloor within a few hundred feet of the wellhead. Although in most cases there is no gas 

content in the waterflow, in these water depths a stream of gas bubbles may form frozen gas 

hydrates at the sea bottom and on flat surfaces of seafloor drilling equipment. Shallow waterflows 

can result from buried channels filled with more permeable sediment. Abnormally pressured shallow 

sands may result from either rapid slumping or rotating faults or from reworked cut-and-fill channels 

sealed by impermeable mud or clay. In rare cases, hydrates below the mudline could be a source of 

shallow waterflow by melting down hydrates during oil production. Shallow waterflow events can 

cause additional expenditure of time and money for the driller to maintain well control and can lead 

to drilling difficulty up to and including a decision to permanently plug and abandon the well. 

Unanticipated shallow hazards can lead to downhole pressure kicks that range from minor and 

controllable to significant and uncontrollable, and up to and including a serious blowout condition.

Deep-penetration airgun seismic surveys are conducted to obtain data on geological 

formations as deep as 40,000 ft (12,192 m) below the seafloor. Further detailed information on 

airgun surveys may be found in BOEM’s Atlantic OCS Proposed Geological and Geophysical 

Activities: Mid-Atlantic and South Atlantic Planning Areas, Final Programmatic Environmental 

Impact Statement (Atlantic G&G Activities Programmatic EIS) (USDOI, BOEM, 2014a). A G&G 

Programmatic EIS is currently being developed for the GOM (refer to Chapter 1.7). Data from these 

surveys can be used to assess potential hydrocarbon structural and stratigraphic traps and 

reservoirs, and also help to optimally locate exploration, development, and production wells, thus 

maximizing extraction and production from a reservoir. BOEM’s resource evaluation staff uses deep 

2D and 3D seismic data for resource estimation and bid evaluation to ensure that the Government 

receives a fair market value for lease blocks offered.

The vast majority of the underwater sound generated during an airgun survey is attributable 

to the airgun or airgun arrays, survey vessel towing the airgun(s), and additional equipment such as 

electromechanical (HRG non-airgun) tools. An airgun or airgun array releases compressed air into 

the water, creating a sound energy pulse that can penetrate deep beneath the seafloor.

Airgun arrays are broadband sound sources that project energy over a wide range of 

frequencies, from less than 10 Hertz (Hz) to more than 2,000 Hz (2 kilohertz [kHz]). Most of the 

usable energy, however, is concentrated in the frequency range below 200 Hz. The energy level 

produced by an airgun array depends primarily on three factors:
3-12 Gulf of Mexico Multisale EIS

• the firing pressure in pounds per square inch (psi) of the guns (2,000 psi for most 

of the surveys currently being conducted);

• the number of airguns in the array (generally between 20 and 80); and

• the total volume in cubic inches of the array (generally between 1,500 and 

8,640 cubic inches).

The output of an airgun array is directly related to the firing pressure and to the number of 

guns and is only proportional to the cube root of the volume. The airguns in the array are arranged 

to project the maximum amount of seismic energy vertically into the seafloor. Nonetheless, a 

significant portion of the sound energy from the array is emitted at off-vertical angles and spreads 

into the surrounding environment. Most of the sound energy is directed downward. The frequency 

spectrum of the sound spreading near-horizontally can differ markedly from that of the sound 

directed downward. There also can be substantial differences in the intensity and frequency 

spectrum of sound spreading in different horizontal directions.

Data acquisition generally takes place day and night and, depending on the size of the 

survey area, may continue for days, weeks, or months. A typical deep-penetration seismic airgun 

survey may experience approximately 20-30 percent of non-operational downtime due to a variety of 

factors, including technical or mechanical problems, standby for weather or other interferences, and 

performance of mitigating measures (e.g., ramp-up, pre-survey visual observation periods, and 

shutdowns).

There are several different types/methods of performing airgun surveys dependent upon the 

data needs. These range from 2D, 3D, and 4D techniques more commonly used in the prelease 

phase to various vertical seismic profiling (VSP) techniques (e.g., zero-offset, multiple-offset, 

walk-away, and checkshot surveys), as well as HRG airgun surveys more commonly used during 

postlease operations.

Checkshot surveys are similar to zero-offset VSP but (1) are less complex and require less 

time to conduct, (2) produce less information, (3) are cheaper, (4) use a less sophisticated borehole 

seismic sensor, and (5) acquire shorter data records at fewer depths. During a checkshot survey, a 

seismic sensor is sequentially placed at a few depths (<20) in a well, and a seismic source (almost 

always an airgun) is hung from the side of the well platform. Only the first energy arriving at the 

sensor from the seismic source is permanently recorded. No reflection events are recorded, and no 

sophisticated data processing like that for VSP surveys are required. The purpose of a checkshot 

survey is to estimate the velocity of sound in rocks penetrated by the well. Typically, the depths at 

which the sensors are placed are at, or near, the boundaries of prominent lithologic features. 

Checkshot surveys can be conducted much quicker than other VSP surveys, but they produce much 

less information. Because checkshot surveys are much less expensive and do not use the wellbore 

and the drilling rig as long, they are much more common than other VSP surveys. In most 

checkshot surveys, the seismic source is hung from the platform in a fixed location within the water 

column, so a surface vessel is not needed. Because reflection energy does not need to be acquired, 
Impact-Producing Factors and Scenario 3-13

the seismic source usually is smaller than those used for other VSP surveys. Detailed descriptions 

of other VSP survey methods are summarized in BOEM’s Atlantic G&G Activities Programmatic EIS 

(USDOI, BOEM, 2014a).

Both 2D and 3D towed-streamer seismic exploration surveys are conducted off-lease by 

geophysical contractors either on a proprietary or nonexclusive (multiclient) basis. Proprietary 

surveys usually cover only a few blocks for an individual client who will then own the data and 

therefore will have exclusive use of it. In contrast, nonexclusive (multiclient or speculative) survey 

data are owned by the contractor, are generally collected over large multi-block areas, and are 

licensed to as many clients as possible to recover costs and produce profits for the contractor.

Newer acquisition technology involves multiple vessels towing airgun arrays with additional 

vessels towing streamers. These 3D WAZ surveys increase the illumination of many subsurface 

areas, particularly areas that are overlain with salt, and eliminate unwanted noise attenuation. The 

3D coil surveys are a navigational variation of WAZ surveys and are acquired in a spiral fashion that 

allows for a longer acoustical distance between source and receivers for a better illumination of the 

acquired data and do not involve vessel turning and repositioning associated with linear acquisition. 

Detailed descriptions of the different airgun survey methods are summarized in BOEM’s Atlantic 

G&G Activities Programmatic EIS (USDOI, BOEM, 2014a).

Electromechanical/HRG Non-airgun Surveys

Electromechanical (also referred to as HRG non-airgun surveys) surveys use a higher 

frequency, low-energy sound signal that is emitted and reflected back to the source. The survey 

equipment is either mounted to the ship or remotely operated vehicle (ROV), conducted using an 

autonomous underwater vehicle, or towed behind a survey vessel. The sound source and receiver 

can be located in a single piece of equipment or the sound source is collected by towed 

hydrophones. When conducted for oil and gas exploration and development, these seafloor- to 

shallow-focused subbottom penetration surveys are used to identify benthic/biological 

communities/habitats, archaeological resources, seafloor bathymetry, geological hazards, and 

seafloor engineering.

There are several different types of HRG non-airgun (electromechanical) equipment used to 

meet the data needs and different sound levels (frequencies) used for different mapping resolutions. 

The specific frequency used would depend on the manufacturer, water depth, purpose of the survey, 

and seabed characteristics in the area of interest. Detailed descriptions of the different 

electromechanical/HRG non-airgun survey methods are provided in BOEM’s Atlantic G&G Activities 

Programmatic EIS (USDOI, BOEM, 2014a). A G&G Programmatic EIS is currently being developed 

for the GOM (refer to Chapter 1.7).

Gravity and Electromagnetic Surveys

Measurements of the earth’s gravity and magnetic fields are useful in helping to determine 

geologic structures in the subsurface. Such data are useful in frontier exploration areas and as a 
3-14 Gulf of Mexico Multisale EIS

complement to seismic data in well-explored areas. Gravity and magnetic surveys are conducted 

from ships, in conjunction with airgun and electromechanical surveys, aircraft, or, very rarely, are 

conducted using an autonomous underwater vehicle. The types of surveys that help map oil and 

gas resources by measuring earth’s magnetic and gravity fields are summarized in BOEM’s Atlantic 

G&G Activities Programmatic EIS (USDOI, BOEM, 2014a).

Geological Surveys

Geological surveys are conducted to obtain information about surface and subsurface 

geological and geotechnical characteristics. For oil and gas purposes, this information is used to aid 

in the following:

• siting, design, construction, and operation of production facilities; 

• assessment of sediment, stratigraphy, and geology (i.e., potential hydrocarbon

source rock) characteristics; and 

• evaluation of subsurface properties, such as the presence of gas hydrates or 

hazards to drilling and/or physical structures.

There are several different types of survey methods used to obtain geological/geotechnical 

information, including grab and box sampling, geologic coring, and shallow test drilling. Detailed 

descriptions of the different geological surveys are summarized in BOEM’s Atlantic G&G Activities 

Programmatic EIS (USDOI, BOEM, 2014a). As noted earlier, a G&G Programmatic EIS is currently 

being developed for the GOM (refer to Chapter 1.7).

G&G Data Acquisition

Geological and geophysical (G&G) surveys conducted as a result of a lease sale typically 

collect data on surficial or near-surface geology used to identify on-lease potential shallow geologic 

hazards for engineering and site planning for bottom-founded structures. The G&G regulations and 

processes are discussed in Appendix A.1. The G&G activities for oil and gas exploration are 

authorized on the basis of whether or not the proposed activities are (1) before leasing takes place 

(prelease) and authorized by permits or (2) on an existing lease (postlease or ancillary) and 

authorized by OCS plan approvals, plan revisions, or by a requirement for notification of BOEM 

before certain on-lease activities are undertaken. BOEM’s resource evaluation program oversees 

G&G data acquisition and permitting activities pursuant to regulations at 30 CFR parts 550 and 551. 

There are a variety of G&G activities that are conducted for oil and gas exploration and development 

as on-lease activities:

• various types of deep-penetration seismic airguns used almost exclusively for oil 

and gas exploration;

• electromagnetic surveys, deep stratigraphic and shallow test drilling, and various 

remote-sensing methods in support of oil and gas exploration;
Impact-Producing Factors and Scenario 3-15

• high-resolution geophysical (HRG) surveys (airgun and non-airgun) used to 

detect and monitor geohazards, archaeological resources, and certain types of 

benthic communities; and

• geological and geotechnical bottom sampling used to assess the suitability of 

seafloor sediments for supporting structures (e.g., platforms, pipelines, and 

cables), as well as to identify environmental resources such as chemosynthetic 

communities, gas hydrates, buried channels and faults, and archaeological 

resources.

Due to the cyclic nature in the acquisition of seismic surveys, a prelease seismic survey 

would be attributable to lease sales held up to several years after the survey. In preparing the G&G 

activity forecast, BOEM began with a short-term forecast of two-dimensional (2D) and threedimensional (3D) G&G activities based on historical relationships. Between 1968 and 2014 about 

1,860,000 line miles of 2D data were acquired. Between 1993 and 2014 about 250,000 OCS blocks 

of 3D data were acquired. In constructing the current forecast, BOEM projected the number of 

narrow azimuth (NAZ) and wide azimuth (WAZ) 3D survey blocks for each planning area. The NAZ 

and WAZ 3D survey blocks were then added to generate a baseline forecast which was then 

anchored to the level of exploratory well drilling activities. This process defined a level of exploration 

effort per block of 3D seismic acquired. This forecast was then compared with historical 2D line 

miles and 3D blocks actually acquired in the GOM since 1968 (1993 for 3D) to ensure that the longterm projections were within the range of historical values. For 2D line mile projections, the number 

of permits forecasted was then derived through the average number of miles per permit issued using 

historical data, exploration well drilling effort from the exploration and development scenarios, and 

data from currently pending applications. BOEM conservatively assumed that one HRG survey 

would occur for every block leased (estimated by the number of production structures predicted) and 

that one HRG survey would occur for every 5 km (3 mi) of pipeline laid (the average length of a 

pipeline permit). To estimate VSP surveys, BOEM conservatively assumed that a VSP survey would 

be conducted on 15 percent of all exploration and development wells drilled. The table below 

reflects a reasonable level of G&G surveying activities that could be expected to occur leading up to 

and following scheduled lease sales in the Gulf of Mexico single lease sale areas (2017-2066).

Survey Area

2D 

Surveys 

(mi)

2D 

Permits

3D Lease 

Blocks

3D 

Permits

Ancillary 

Permits

HRG 

Surveys

VSP 

Surveys

Regionwide 48,000-

650,000

31-310 13,400-

185,000

25-128 19-214 87-709 17-263

CPA/EPA 47,000-

603,000

27-283 18,900-

171,300

20-108 16-198 64-576 11-234

WPA 900-4,100 4-9 5,500-

25,100

6-21 3-26 30-134 5-29
3-16 Gulf of Mexico Multisale EIS

The term exploration well generally 

refers to the first well drilled on a 

prospective geologic structure to confirm 

that a resource exists and to validate 

how much resource can be expected.

If any action is proposed in an area of archaeological concern, BOEM or BSEE’s Regional 

Directors may also require the preparation of an archaeological report (which may include a sitespecific survey) to accompany the exploration (EP), development operations and coordination 

document (DOCD), or development and production plan (DPP) under 30 CFR § 250.194(c) and 

30 CFR § 550.194(c). Refer to Chapter 4.1.3 for information on archaeological requirements and 

impacts to archaeological resources.

Alternative A, B, or C*: For each alternative, seismic surveys are projected to follow the 

same trend as exploration drilling activities, which would peak in 2030-2040 and decline until 

2060, with regards to a particular lease sale. Geophysical surveys generally would be the first 

activities to occur within the Gulf of Mexico. The HRG surveys generally occur before exploratory 

drilling, but they can also occur before development drilling, platform and pipeline installation, and 

decommissioning activities. It is important to note that the cycling of G&G data acquisition is not 

driven by the 50-year life cycle of a single productive lease but instead would tend to respond to 

new production or potential new production driven by new technology. Consequently, some areas 

would be resurveyed in 2-year cycles, while other areas, considered nonproductive, may not be 

surveyed for 20 years or more. The above estimates far exceed the number of blocks available 

for leasing in the entire Gulf of Mexico OCS. Data collection may be repeated on any one block 

as technology advances, or multiple surveys may be conducted over the same OCS blocks for 

different purposes (e.g., prelease exploratory surveys and shallow hazard surveys).

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

3.1.2.2 Exploration and Delineation Plans and Drilling

Oil and gas operators use drilling terms that 

represent stages in the discovery and development of 

hydrocarbon resources. If a resource is discovered 

during the drilling of an exploration well in quantities 

appearing to be economically viable, one or more 

follow-up delineation wells are drilled. Refer to Figure 

3-2 above for a typical exploration and production 

timeline of an oil or gas lease. 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. Following a discovery, an operator often temporarily 

plugs and abandons the well to allow time for a development plan to be generated and for 

equipment to be built or procured.

In the GOM, exploration and delineation wells are typically drilled with mobile offshore drilling 

units (MODUs) (i.e., jack-up rigs, semisubmersible rigs, submersible rigs, platform rigs, or drill ships). 

Non-MODUs, such as inland barges, are also used. The type of rig chosen to drill a prospect 

depends primarily on water depth, though the water-depth ranges for each type of drilling rig do 
Impact-Producing Factors and Scenario 3-17

overlap to a degree. Other factors such as availability and daily rates also play a large role when an 

operator decides upon the type of drilling rig to contract. The water-depth ranges for drilling rigs 

used in this analysis are listed 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 each alternative assumes that an average exploration well would require 

6-10 weeks to drill per well, and more than one well can be drilled at a location. 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 would be approximately 4,210-8,080 m (13,800-26,500 ft) below the mudline.

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 their 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. 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.
3-18 Gulf of Mexico Multisale EIS

Figure 3-3 represents a generic 

well schematic for a relatively shallow 

exploration well in the deepwater GOM. 

This well design was abstracted from 

actual well-casing programs from 

projects in the Mississippi Canyon and 

De Soto Canyon Areas and from 

internal BOEM data. A generic well 

configuration cannot capture all of the 

possible influences that impact how a 

well is designed. These influences 

include (1) unique geologic conditions 

at a specific well location, (2) directional 

drilling requirements, (3) potential 

sidetrack(s), or (4) company 

preferences. For exploration wells, 

contingencies (such as anticipated 

water-flow zones in the formation) must 

also be considered in the casing 

program.

For exploration and 

development, deep water is defined as 

water ≥1,000 ft (≥305 m) deep and 

ultra-deepwater is defined as water 

≥5,000 ft (≥1,524 m) deep. The drilling 

(spudding) of a deepwater exploration 

well begins with setting the conductor 

casing, one of the many sections or 

strings of casing (steel tube) installed in 

the wellbore. The first casing set in the 

sea bottom (or mudline) can be large, 

approximately 30-40 in (75-100 cm) in 

diameter. The larger diameter pipe may be necessary when drilling through salt to reach subsalt 

objectives because more casing strings may be needed to reach the well’s objective. The first string 

is emplaced by drilling or “jetting” out the unconsolidated sediment with a water jet as the largest 

casing pipe is set in place. The casing is cemented to the sea bottom and tested. Because the 

shallow sediments are frequently soft and unconsolidated, the next casing interval (1,000 ft [305 m] 

or more below mudline) is commonly drilled with treated seawater and without a riser (a steeljacketed tube that connects the wellhead to the drill rig and within which the drilling mud and cuttings 

circulate). Because a riser is not used, the formation cuttings are typically discharged from the 

wellbore directly to the sea bottom unless the location is near sensitive bottom areas (NTL 

2009-G40). Muds and cuttings are discussed further in Chapter 3.1.5.1.1. After the conductor 

Figure 3-3. General Well Schematic (USDOI, 2010) (not to 

scale).
Impact-Producing Factors and Scenario 3-19

casing is set, a blowout preventer (BOP) would be installed, commonly at the sea bottom, the riser 

connected, and circulation for drilling muds and cuttings between the well bit and the surface rig 

established.

Next, a repetitive procedure would take place until the well reaches its planned total depth: 

(1) drill to the next casing point; (2) install the casing; (3) cement the casing; (4) test the integrity of 

the seal; and (5) drill through the cement shoe and downhole until the next casing point is reached 

and a narrower casing string is then set.

As drilling activities occur in progressively deeper waters, operators may consider using 

MODUs that have onboard hydrocarbon storage capabilities. This option may be exercised if a well 

requires extended flow testing (1-2 weeks or longer) in order to fully evaluate potential producible 

zones and to justify the higher costs of deepwater development activities. The liquid hydrocarbons 

resulting from an extended well test could be stored onboard a rig and later transported to shore for 

processing. Operators may also consider barge shuttling hydrocarbons from test well(s) to shore. 

There are some dangers inherit with barging operations if adverse weather conditions develop 

during testing. If operators do not choose to store produced liquid hydrocarbons during the well 

testing, they must request and receive approval from BSEE to burn test hydrocarbons. The BSEE 

would only grant permission to flare or vent associated natural gas during well cleanup and for welltesting procedures for a limited period of time.

The regulation at 30 CFR part 550 subpart B specifies the requirements for the exploration 

plans (EPs) that operators must submit to BOEM for approval prior to deploying an exploration 

program. Refer to Appendix A.2 for a detailed discussion of regulations, processes, and 

environmental information requirements for lessees and operators related to EPs, operation plans, 

and DOCDs. Refer to Chapters 1.3.1 and 3.1.10.3, which provide a summary of new safety 

requirements.

Following a lease sale, exploratory drilling activity would likely occur over the course of each 

lease but could begin within 1 year. The majority of the exploratory drilling for all blocks leased 

would likely occur early and would generally be complete by the 25th year. Refer to Figure 3-4

below.
3-20 Gulf of Mexico Multisale EIS

Figure 3-4. Number of Exploration and Delineation Wells Drilled over the Course of a 

Proposed Action under Alternative A for 50 Years.

Alternative A*: BOEM estimates that 53-984 exploration and delineation wells would be 

drilled as a result of forecasted activity associated with Alternative A. Table 3-2 shows the 

estimated range of exploration and delineation wells by water-depth range. Of these wells,

60-94 percent are expected to be on the continental shelf (0-200 m [0-656 ft] water depth) and 

40-6 percent are expected in water-depth ranges >200 m (656 ft). The projected number of 

exploration and delineation wells that would be drilled over the course of a proposed action under 

Alternative A can be seen in Figure 3-4 above (including the low production scenario and a high 

production scenario).

Alternative B*: BOEM estimates that 33-893 exploration and delineation wells would be 

drilled as a result of forecasted activity associated with Alternative B. Table 3-2 shows the 

estimated range of exploration and delineation wells by water-depth range. Approximately 

75-85 percent of the projected wells in the CPA and EPA are expected to be on the continental 

shelf (0-200 m [0-656 ft] water depth) and about 25-15 percent are expected in water-depth 

ranges >200 m (656 ft).

Alternative C*: BOEM estimates that 17-91 exploration and delineation wells would be 

drilled as a result of forecasted activity associated with Alternative C. Table 3-2 shows the 

estimated range of exploration and delineation wells by water-depth range. Approximately 

35-78 percent of the projected wells are expected to be on the continental shelf (0-200 m [0-656 

ft] water depth) and 65-22 percent are expected in water-depth ranges >200 m (656 ft).

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to

4 percent. Refer to Chapter 2.2.2.4 for more information.
Impact-Producing Factors and Scenario 3-21

A development well is drilled to 

extract resources from a known 

hydrocarbon reservoir.

3.1.3 Offshore Development and Production 

3.1.3.1 Development and Production Drilling

Delineation and production wells are sometimes 

collectively termed development wells. After a development 

well is drilled, the operator must decide whether or not to 

complete the well without delay, to delay completion with the 

rig on station so that additional tests may be conducted, or to 

temporarily abandon the well site and move the rig off station to a new location and drill another well. 

Sometimes an operator may decide to drill a series of development wells, move off location, and 

then return with a rig to complete all the wells at one time. If an exploration well is clearly a dry hole, 

the operator would typically permanently abandon the well without delay, but could convert the well 

into an injection well.

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 would be drilled 

specifically for the purpose of extracting hydrocarbons from the subsurface and therefore 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 that the operator may 

decide to move off location and delay the work required to prepare the wells for production; for 

example, additional well tests may be required or the drilling rig may be committed to another 

location. When a decision to delay the work is chosen, each development well would be temporarily 

abandoned before the drilling rig can be moved to another location. It is also common for an 

operator to drill the required number of development wells in stages, leaving some time between the 

well drilling stages to evaluate the information obtained from the wells and, if necessary, use this 

information to modify the development program.

Well Completions

The process that includes the suite of activities that are carried out to prepare a development 

well for production is referred to as the completion process. 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. 
3-22 Gulf of Mexico Multisale EIS

When the decision is made to perform a well completion, a new stage of activity begins. BOEM 

estimates that approximately 63-70 percent of wells drilled as development wells 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 a “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. The term “frac pack” has become an industry-recognized term for the completion 

process of fracturing and gravel packing and is the most widely used completion technique for sand 

control in the Gulf of Mexico. The “frac pack” process, which has been used in the Gulf of Mexico for 

more than 25 years, combines the production improvement from hydraulic fracturing (see below) with 

the sand control provided by gravel packing. 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 would be 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. 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 flow restrictions caused by a reduction 

in permeability in the near-wellbore region (also known as formation “damage”) 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. 

The term hydraulic fracturing covers a broad range of techniques used to stimulate and 

improve production from a well. Fracture fluid is injected into a wellbore at high pressure to break 

open the rock to create/ improve the flow path for hydrocarbon to flow in to the well. 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 fracture pack or “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 high-density, 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 
Impact-Producing Factors and Scenario 3-23

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 fracture 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 formation “damage” 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 (Ali et al., 2002; Sanchez and Tibbles, 2007) to 

prevent the production of formation fines and sand.

Additives used in fracture-pack operations are often similar, if not identical, to those used for 

shale or tight sand development onshore and 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 permeability and lower amounts of clay/shale in typical formations (API, 

2015). Another factor that can substantially 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 22 functional categories of additives and 2 categories of 

proppants used offshore in the GOM for fracturing activities:

—water-based polymers

—defoamers

—friction reducers

—oil gelling additives

—fluid loss additives

—biocides

—breakers 

—acid-based gel systems

—emulsifiers 

—water-based systems

—clay stabilizers 

—cross-linked 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 offers a chemical inventory with 

example products and Material Safety Data Sheets for those products. In general, discharges of any 
3-24 Gulf of Mexico Multisale EIS

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 selected 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 in Chapter 3.1.5. 

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 would 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 chapters throughout this Multisale EIS; these impacts include 

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.

Deepwater Operations Plans and Development Activity

A deepwater operations plan is required for all deepwater development projects in water 

depths ≥1,000 ft (305 m) and for all projects proposing subsea production technology. A deepwater 

operations plan is required initially and is usually followed by a DOCD. The DOCD is the chief 

planning document that lays out an operator’s specific intentions for development. Refer to 

Appendix A.2 for a detailed discussion on regulations, processes, and environmental information 

requirements for lessees and operators related to EP’s, deepwater operations plans, and DOCDs.

Development activity during a proposed action usually takes place over a 49-year period, 

beginning with the installation of a production platform on the first lease and ending with the drilling 

of the last development wells. The majority of development well drilling would likely occur in the first 

25 years of each lease. Production of oil and gas could begin by the third year after the lease sale 

and generally would conclude by the 50th year; refer to Figure 3-5 below.
Impact-Producing Factors and Scenario 3-25

Figure 3-5. Number of Production Wells Drilled over the Course of a Proposed Action 

under Alternative A for 50 Years.

Alternative A*: It is estimated that 61-767 development and production wells would be 

drilled as a result of forecasted activity associated with Alternative A. Table 3-2 shows the 

estimated range of development wells by water depth. Between 14 and 71 percent of the 

projected wells are expected to be on the continental shelf (0-200 m [656 ft] water depth) and 

86 to 29 percent are expected in water-depth ranges >200 m (656 ft). Trends between the oil and 

gas development wells are markedly different. Deeper water depths (200-1,600 m; 656-5,249 ft) 

have a larger portion of projected producing oil wells, while shallow water (0-200 m; 0-656 ft) has 

a greater percentage of projected producing gas wells. The projected number of production wells 

that would be drilled over the course of a proposed action under Alternative A can be seen in 

Figure 3-5 above (including the low production scenario and a high production scenario).

Alternative B*: BOEM estimates that 46-671 development and production wells would be 

drilled as a result of Alternative B. Table 3-2 shows the estimated range of development and 

production wells by water-depth subarea. The percentage of projected oil wells within the 

CPA/EPA is more evenly distributed throughout the water-depth ranges. Gas wells for Alternative 

B follow the same trends as Alternatives A and C. A majority of the gas wells (70-89%) are 

projected to be drilled on the continental shelf (0-200 m [0-656 ft] water depth).
3-26 Gulf of Mexico Multisale EIS

Alternative C*: BOEM estimates that 22-96 development and production wells would be 

drilled as a result of Alternative C. Table 3-2 shows the estimated range of development and 

production wells by water-depth subarea. Approximately 36-55 percent of the projected wells are 

expected to be on the continental shelf (0-200 m [656 ft] water depth) and 64-45 percent are 

expected in deeper water-depth ranges (>200 m; 656 ft). While a majority of oil wells (100-77%) 

are projected to be drilled in the deeper water depths (200-1,600 m; 656-5,249 ft), a majority of 

gas wells (80-71%) are projected to be drilled in shallow water (0-200 m; 0-656 ft).

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

3.1.3.2 Offshore Production Systems

After the approval of an EP or 

DOCD, the operator submits 

applications for specific activities, 

including production systems, to BOEM 

for approval. Refer to Appendix A.3

for more information on permits and 

applications related to offshore 

production systems.

Development wells may be 

drilled from movable structures, such 

as jack-up rigs, fixed bottom-supported 

structures, floating vertically moored 

structures, floating production facilities, 

and drillships (either anchored or 

dynamically positioned drilling vessels) 

(Figure 3-6). The spectrum of these 

production systems is discussed in 

Chapter 3.1.3.2 below.

The type of production 

structure installed at a site depends 

mainly on water depth, but the total 

facility lifecycle, type and quantity of 

hydrocarbon production expected, number of wells to be drilled, and number of anticipated tie backs 

from other fields can also influence an operator’s procurement decision. The number of wells per 

structure varies according to the type of production structure used, the prospect size, and the 

drilling/production strategy deployed for the drilling program and for resource conservation. 

Production systems can be fixed, floating, or, increasingly in deep water, subsea. Advances in the 

Figure 3-6. Offshore Production Systems.
Impact-Producing Factors and Scenario 3-27

composition of drilling fluids and drilling technology are likely to provide operators with the means to 

reduce rig costs in the deepwater OCS program.

Until recently, there had been a gradual increase of drilling depth (as measured in true 

vertical depth). Beginning in 1996, the maximum drilling depth increased rapidly, reaching depths 

below 30,000 ft (9,144 m) in 2002. In 2013, Cobalt International Energy drilled the Ardennes #1 

exploration well (Green Canyon Block 896), reaching a true vertical depth of 36,552 ft (11,141 m). 

The recent dramatic increase in true vertical depth may be attributed to several factors, including 

enhanced rig capabilities, deeper exploration targets, royalty relief for shallow water, deep gas 

prospects, and the general trend toward greater water depths.

BOEM has described and characterized production structures in its deepwater reference 

document (USDOI, MMS, 2000a). These descriptions are summarized below and were used in 

preparing the scenario for this Multisale EIS. In water depths of up to 400 m (1,312 ft), the scenarios 

assume that conventional, fixed platforms that are rigidly attached to the seafloor would be the type 

of structure preferred by operators. In water depths of <200 m (656 ft), 20 percent of the platforms 

are expected to be manned (defined as having sleeping quarters on the structure). In depths 

between 200 and 400 m (656 and 1,312 ft), all structures are assumed to be manned. It is also 

assumed that helipads would be located on 66 percent of the structures in water depths <60 m 

(197 ft), on 94 percent of structures in water depths between 60 and 200 m (656 ft), and on 

100 percent of the structures in water depths >200 m (656 ft). At water depths >400 m (1,312 ft), 

platform designs based on rigid attachment to the seafloor are not expected to be used. The 400-m 

(1,312-ft) isobath appears to be the current economic limit for this type of structure.

Fixed Platforms

A fixed platform consists of a welded tubular steel jacket, deck, and surface facility. The 

jacket and deck make up the foundation for the surface facilities. Piles driven into the seafloor 

secure the jacket. The water depth at the intended location dictates the height of the platform. Once 

the jacket is secured and the deck is installed, additional modules are added for drilling, production, 

and crew operations. Large, barge-mounted cranes position and secure the jacket prior to the 

installation of the topsides modules. While the base dimensions are typically around 200,000 ft2

(18,581 m2

), the topside modules is typically only 40,000 ft2 (3,716 m2). Economic considerations 

limit development of fixed (rigid) platforms to water depths no greater than 1,500 ft (457 m) (USDOI, 

MMS, 2000a).

A caisson is a fixed platform that consists of a single vertical column that rises from the 

seabed and supports a small surface facility above the water. This is termed a free-standing 

caisson. A braced caisson has the same general structure, but the column is laterally supported by 

one or more inclined braces. Caissons are not generally designed to be manned.
3-28 Gulf of Mexico Multisale EIS

Compliant Towers

Compliant towers are similar to fixed platforms in that they have a steel tubular jacket that is 

used to support the surface facilities. Unlike fixed platforms, compliant towers yield to the water and 

wind movements in a manner similar to floating structures. Like fixed platforms, they are secured to 

the seafloor with piles. The jacket of a compliant tower has smaller dimensions than those of a fixed 

platform and may consist of two or more sections. It can also have buoyant sections in the upper 

jacket with mooring lines from jacket to seafloor (guyed-tower designs) or a combination of the two. 

The water depth at the intended location dictates platform height. Once the lower jacket is secured 

to the seafloor, it acts as a base (compliant tower) for the upper jacket and surface facilities. Large 

barge-mounted cranes position and secure the jacket and install the surface facility modules. These 

differences allow the use of compliant towers in water depths ranging up to 3,000 ft (914 m). The 

base dimensions of a compliant tower are typically smaller than a fixed platform and is only around 

90,000 ft2 (8,361 m2

), and the topside modules are typically only 40,000 ft2 (3,716 m2). This range is 

generally considered to be beyond the economic limit for fixed jacket-type platforms (USDOI, MMS, 

2000a).

Spar

A spar is a deep-draft floating caisson, which is a hollow cylindrical structure approximately 

90-120 ft (27-36 m) in diameter similar to a very large buoy. Its four major systems are hull, 

moorings, topsides, and risers. The spar relies on a traditional mooring system (i.e., anchor-spread 

mooring) to maintain its position. About 90 percent of the structure is underwater and supports a 

conventional production deck (USDOI, MMS, 2000a). A third generation of spar design is the cell 

spar. The cell spar’s hull is composed of several identically sized cylinders surrounding a center 

cylinder. The cylinder or hull may be moored via a chain catenary or semi-taut line system 

connected to 6-20 anchors on the seafloor. Spars are now used in water depths up to 900 m 

(2,953 ft) and may be used in water depths of 3,000 m (9,843 ft) or deeper (NaturalGas.org, 2010; 

USDOI, MMS, 2006; Oynes, 2006).

Tension-Leg Platform

A tension-leg platform (TLP) is a buoyant platform held in place by a mooring system. The 

TLPs are similar to conventional fixed platforms except that the platform is maintained on location

through the use of moorings held in tension by the buoyancy of the hull. The mooring system is a 

set of tension legs or tendons attached to the platform and connected to a template or foundation on 

the seafloor. Tendons are typically steel tubes with dimensions of 2-3 ft (0.6-0.9 m) in diameter with 

up to 3 in (8 cm) of wall thickness, with the length depending on water depth. A typical TLP would 

be installed with as many as 16 tendons. The template is held in place by piles driven into the 

seafloor. This method dampens the vertical motions of the platform but allows for horizontal 

movements. The topside facilities (i.e., processing facilities, pipelines, and surface trees) of the TLP 

and most of the daily operations are the same as for a conventional platform (USDOI, MMS, 2000a).
Impact-Producing Factors and Scenario 3-29

Semisubmersibles

Semisubmersible production structures (semisubmersibles) resemble their drilling rig 

counterparts and are the most common type of offshore drilling rig (NaturalGas.org, 2010). 

Semisubmersibles are partially submerged with pontoons that provide buoyancy. Their hull contains 

pontoons below the waterline and vertical columns that connect to the hull box/deck. The structures 

keep on station with conventional, catenary, or semi-taut line mooring systems connected to anchors 

in the seabed. Semisubmersibles can be operated in a wide range of water depths. Floating 

production systems are suited for deepwater production in depths up to 8,000 ft (26,437 m) 

(NaturalGas.org, 2010; USDOI, MMS, 2006; Oynes, 2006).

Subsea Production Systems

For some development programs, especially those in deep and ultra-deepwater, an operator 

may choose to use a subsea production system instead of a floating production structure. Although 

the use of subsea systems has recently increased as development has moved into deeper water, 

subsea systems are not new to the GOM and they are not used exclusively for deepwater 

development. Unlike wells from conventional fixed structures, subsea wells do not have surface 

facilities directly supporting them during their production phases. A subsea production system has 

various bottom-founded components. Among them are well templates, well heads, “jumper” 

connections between well heads, flow control manifolds, in-field pipelines and their termination

sleds, and umbilicals and their termination assemblies. A subsea production system can range from 

a single-well template connected to a nearby manifold or pipeline to a riser system at a distant 

production facility or a series of wells that are tied into the system. Subsea systems rely on a “host” 

facility for support and well control. Centralized or “host” production facilities in deep water or on the 

shelf may support several satellite subsea developments. A drilling rig would be brought on location 

to provide surface support to reenter a well for workovers and other types of well maintenance 

activities. In addition, should the production/safety system fail and a blowout result, surface support 

must be brought on location to regain control of the well.

Floating Production, Storage, and Offloading Systems

The category of floating production systems referred to as floating production, storage, and 

offloading systems (FPSOs) can normally be characterized as ship-shape vessels (tankers) that 

have been retrofitted (conversions) or purpose built (new built) for this application (USDOI, MMS, 

2000a). Floating systems are differentiated as follows:

• FPSO — floating production, storage, and offloading system; offloading of the 

crude oil to a shuttle tanker; these are typically converted or newly built tankers 

that produce and store hydrocarbons, which are subsequently transported by 

other vessels to terminals or deepwater ports.

• FPS — floating production system; universal term to refer to all production 

facilities that float rather than are structurally supported by the seafloor; included 

would be TLPs, spars, semisubmersibles, shipshape vessels, etc. The term is 
3-30 Gulf of Mexico Multisale EIS

also frequently used to describe the general category of floating production 

facilities that do not have onsite storage. The term is also used by the American 

Bureau of Shipping to describe a classification of floating production facilities that 

do not have storage capability.

• FSO — floating storage and offloading system; like the FPSO, these are typically 

converted or newly built tankers. They differ from the FPSO by not incorporating 

the processing equipment for production; the liquids are stored for shipment to 

another location for processing.

BOEM’s predecessor prepared an EIS on the potential use of FPSOs on the Gulf of Mexico 

OCS (USDOI, MMS, 2001). In accordance with the scenario provided by industry, the FPSO

environmental impact statement addresses the proposed use of FPSOs in the deepwater areas of 

the CPA and WPA only. In January 2002, this Agency announced its decision to accept applications 

for FPSOs after a rigorous environmental and safety review. Petrobras Americas Inc. developed the 

first FPSO to come online in the GOM and began production in June 2012 from two prospects. The 

Cascade Prospect (Walker Ridge Block 206 Unit) is located approximately 250 mi (402 km) south of 

New Orleans, Louisiana, and about 150 mi (241 km) from the Louisiana coastline in approximately 

8,200 ft (2,499 m) of water. The Chinook Prospect (Walker Ridge Block 425 Unit) is located about 

16 mi (26 km) south of the Cascade Prospect. A second FPSO is being developed by Shell and is 

expected to begin production in 2016.

3.1.3.3 Infrastructure Emplacement/Structure Installation and Commissioning Activities

Structures described in Chapter 3.1.3.2 may be placed over development wells to facilitate 

production from a prospect. These structures provide the means to access and control wells. They 

serve as a staging area to process and treat produced hydrocarbons from wells, initiate export of 

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.

Subsea wells may also be completed to produce hydrocarbons from on the shelf and in the 

deepwater portions of the GOM. The subsea completions would require a host structure to control 

their flow and to process their well stream. Control of the subsea well is accomplished via an 

umbilical from the host.

Pipelines are the primary means of transporting produced hydrocarbons from offshore oil 

and gas fields to distribution centers or onshore processing points. Pipelines range from smalldiameter (generally 4-12 in; 10-30 cm) gathering lines, sometimes called flowlines, that link 

individual wells and production facilities to large-diameter (as large as 36 in; 91 cm) lines, sometimes 

called trunk lines, for transport to shore. Pipelines would typically be installed by lay barges that are 

either anchored or dynamically positioned while the pipeline is laid. Pipeline sections may be 

welded together on a conventional lay barge as it moves forward on its route or they may be welded 
Impact-Producing Factors and Scenario 3-31

together at a fabrication site onshore and wound onto a large-diameter spool or reel. Once the reel 

barge is on location, the pipeline is straightened and lowered to the seafloor on its intended route. 

Both types of lay barge use a stinger to support the pipeline as it enters the water. The stinger helps 

to prevent undesirable bending or kinking of the pipeline as it is installed. In some cases, pipelines 

or segments of pipelines are welded together onshore or along a beach front area and then towed 

offshore to their location for installation. In a typical offshore operation, a lay barge would move one 

pipe length every 15 minutes, while third-generation barges may achieve rates of a mile per day 

(Wolbers and Hovinga, 2003). The rate of progress depends on the lay barge type, crew 

experience, and weather. Additional information on pipeline installation can be found in Chapter 

3.1.4.4 below.

Fixed, jacketed platforms are the most common surface structures of the GOM (refer to 

Chapter 3.1.3.2) and account for about 60 percent of all bottom-founded surface structures on the 

shallow continental shelf. Fixed platforms are brought on location as a complete unit or in sections 

on an installation barge towed by powerful tug boats. If the structure is fabricated in sections, it is 

generally composed of two segments: the jacket and the deck. Accidents have occurred during the 

vulnerable period when heavy equipment is held only by cranes. In December 1998, the 3,600-ton 

topside structure for the Petronius compliant tower was lost in 1,750 ft (533 m) of water as it was 

being lifted into place by the lift barge in Viosca Knoll Block 892.

The platform’s tubular-steel jacket would then be launched from the barge, upended, and 

lowered into position by a derrick barge with a large crane. The jacket is anchored to the seafloor by 

piles driven through the legs. The deck section with one or more levels is then lifted atop the jacket 

and welded to the foundation. The platform may have a helipad installed on its deck section. 

Platforms may or may not be manned continuously. The different types of floating platforms are 

discussed in Chapter 3.1.3.2. 

Caissons are the second most numerous and account for about 30 percent of bottomfounded, surface structures in the GOM. Caissons are typically located primarily on the shallow 

continental shelf. Simpler in design and fabrication than traditional jacketed platforms, most 

caissons consist of a steel pipe that generally ranges from 36 to 96 in (91 to 2.44 cm) in diameter. 

The caisson pipe is driven over existing well(s) to a depth that allows for shoring against varying sea 

states. Though primarily installed for well protection, some caissons may also be used as 

foundations for equipment and termination or relay points for pipeline operations.

Well protectors account for about 10 percent of all bottom-founded surface structures in the 

GOM. Well protectors are used primarily to safeguard producing wells and their production trees 

from boat damage and from battering by floating debris and storms. Similar to fixed platforms, well 

protectors consist of small piled jackets with three or four legs generally less than 36 in (91 cm) in 

diameter, which may or may not support a deck section.

In shallow-water installations, jackets, piles, and topsides are fabricated onshore and 

transported to the site on a cargo barge, and installation times usually range from 2-4 weeks. For 
3-32 Gulf of Mexico Multisale EIS

most deepwater systems, installation activities would extend over a period of 2 or 3 months or more, 

and if a number of wells are subsea, drilling and completion activities may extend over several 

years. The time required to complete the myriad of operations to start production at a structure is 

dependent on the complexity of its facilities.

To keep floating structures on station, a mooring system would be designed and installed. 

Lines to anchors or piling arrays attach the floating components of the structure. With a TLP, 

tendons stem from a base plate on the sea bottom to the floating portion of the structure. 

Commissioning activities involve the emplacement, connecting, and testing of the structure's 

modular components that are assembled on site.

Alternative A*: It is estimated that 16-280 production structures would be installed as a 

result of a lease sale under Alternative A. Table 3-2 shows the projected number of structure 

installations for Alternative A by water-depth range. About 75-96 percent of the production 

structures installed for a proposed action under Alternative A are projected to be on the 

continental shelf (0-60 m; 0-197 ft). The estimated number of production structures operating 

over the life of a proposed action under Alternative A (including the low production scenario and a 

high production scenario) can be seen in Figure 3-7 below.

Alternative B*: It is estimated that 14-247 production structures would be installed as a 

result of a lease sale under Alternative B. Table 3-2 shows the projected number of structure 

installations for Alternative B by water-depth range. About 71-96 percent of all the production 

structures installed under Alternative B are projected to be on the continental shelf (0-200 m; 

0-656 ft).

Alternative C*: It is estimated that 17-91 production structures would be installed as a 

result of a lease sale under Alternative C. Table 3-2 shows the projected number of structure 

installations for Alternative C by water-depth range. About 55-88 percent of all the production 

structures installed for Alternative C are projected to be on the continental shelf (0-60 m; 0-197 ft).

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.
Impact-Producing Factors and Scenario 3-33

Figure 3-7. Number of Production Structures and Service Vessels Operating over the 

Course of a Proposed Action under Alternative A for 50 Years.

3.1.3.3.1 Bottom-Area Disturbance

Structures emplaced or anchored on the OCS to facilitate oil and gas exploration and 

production include drilling rigs or MODUs (i.e., jack-ups, semisubmersibles, and drillships), pipelines, 

and fixed surface, floating, and subsea production systems; these structures are discussed in 

Chapters 3.1.3.2 above. 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 could 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 would also cause the movement of the 

mooring lines in its array. Small areas of the sea bottom would 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, highdensity biological communities in water depths ≥400 m (1,312 ft), and archaeological sites.

Wells drilled in shallow water create a splay of drilling muds and cuttings that spread 250 m 

(820 ft) from the well, and in deepwater (over 300-m [984-ft] water depth) the coverage area would 

be approximately 500 m (1,640 ft) from the well. Muds and cuttings are discussed further in 

Chapter 3.1.5.1.1. There are numerous studies about splays from various areas of the GOM and 

other locations around the world (Neff et al., 2000; USEPA, 2000a; International Association of Oil 

and Gas Producers, 2003). These splays on the seafloor vary from one location to the next and vary 

by well depth, which controls the total volume of cuttings available for disbursement. Variation in 
3-34 Gulf of Mexico Multisale EIS

splay size are caused by water depth, well depth, drilling fluid type (cuttings from oil-based or 

synthetic mud are taken to shore for disposal), and currents. A typical splay is not in a uniform 

circular shape but rather in the shape of a fan that is influenced by prevailing currents and the fall 

rate of drill cuttings; however, for this calculation, disturbance is considered a possibility in all 

directions from a well. The model used here is an oversimplification in order to obtain a conservative 

estimate of disturbance per offshore production system. Given that a splay from a well generally 

overlays the footprint of an offshore production system and creates a larger surface area of 

disturbance, only bottom disturbance from the splay is considered when evaluating overall bottom 

disturbance.

Subsea production systems located on the ocean floor are connected to surface topsides by

a variety of components. These bottom-founded components are an integrated system of flowlines, 

manifolds, flowline termination sleds, umbilicals, umbilical sleds, blowout preventers, well trees, and 

production risers. Richardson et al. (2008) indicated that all currently operating subsea systems are 

tied to an offshore production system. For that reason, any environmental effects resulting from 

these subsea developments are integral parts of the overall environmental effect of the host offshore 

production system and the disturbance created by the system. 

Emplacement of flowlines and export pipelines that cross a fairway disturb between 0.5 and 

1.0 ha (1.2 and 2.5 ac) of seafloor per kilometer of pipeline (Cranswick, 2001). Pipe-laying vessels 

operating in the deepwater Gulf of Mexico rely on dynamic positioning rather than conventional 

anchors to maintain their position during operations and do not require trenching, so deepwater pipelaying is assumed to disturb 0.32 ha (0.79 ac). The variation lies in BSEE’s requirement to bury 

pipelines in water depths <200 ft (61 m) to a depth of 3 ft (1 m). Burial is typically done by water 

jetting a trench followed by placing the pipeline into it.

Alternative A*: Bottom-area disturbance is calculated as a relationship between the 

structures projected (i.e., platforms, wells, subsea structures, and pipeline miles installed 

[Chapter 3.1.4.1]) and the associated disturbance of each. Under Alternative A, between 

1,226 and 21,158 ha (3,029 and 52,282 ac) of sea bottom is projected to be disturbed. This is 

<0.01-0.05 percent of the total area of the Gulf of Mexico.

Alternative B*: Under Alternative B, between 1,056 and 18,648 ha (2,609 and 46,080 ac) 

of sea bottom is projected to be disturbed in the CPA/EPA. This is <0.01-0.03 percent of the total 

area of the Gulf of Mexico.

Alternative C*: Under Alternative C, between 693 and 2,525 ha (1,712 and 6,239 ac) of 

sea bottom is projected to be disturbed in the WPA. This is <0.001-0.01 percent of the total area 

of the Gulf of Mexico.

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.
Impact-Producing Factors and Scenario 3-35

3.1.3.3.2 Sediment Displacement

Displaced sediments are those that have been physically moved “in bulk.” Displaced 

sediments cover or bury an area of the seafloor, while resuspended sediments 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.

The chief means for sediment displacement is the overboard discharge of drill cuttings 

carried to the surface by drilling mud. Cuttings that outfall from surface platforms settle to the sea 

bottom as a mound or plume if influenced by the prevailing currents. Sediment displacement can 

also take place when anchored exploration rigs and production structures are subject to high current 

energy, such as GOM loop currents or hurricane sea states. Mooring lines in contact with the sea 

bottom can scrape sediment into heaps and mounds as the surface facility moves in response to 

currents.

Trenching for pipeline burial causes displacement or resuspension of seafloor sediments. 

Sediment displacement also occurs as a result of the removal of pipelines. It is projected that the 

number of pipeline removals (or relocations) would increase regionwide as the existing pipeline 

infrastructure ages. For each kilometer of pipeline removed in water depths <200 ft (61 m), 

approximately 5,000 m3 (176,573 ft3

) of sediment would be displaced and resuspended (Cranswick, 

2001).

3.1.3.4 Infrastructure Presence

3.1.3.4.1 Anchoring

Most exploration drilling, platform, and pipeline emplacement operations on the OCS require 

anchors to hold the rig, topside structures, or support vessels in place. Anchors disturb the seafloor 

and sediments in the area where dropped or emplaced. Anchoring can cause physical compaction 

beneath the anchor and chains or lines, as well as resuspended sediment. A disturbed area on the 

sea bottom forms by the swing arc formed by anchor lines scraping across bottom within the range 

of the anchoring system configuration. Dynamically positioned rigs, production structures, and 

vessels are held in position by four or more propeller jets and do not cause anchoring impacts. 

Conventional pipe-laying barges use an array of eight 9,000-kg (19,842-lb) anchors to position the 

barge and to move it forward along the pipeline route. These anchors are continually moved as the 

pipe-laying operation proceeds. The area actually affected by these anchors depends on water 

depth, wind, currents, chain length, and the size of the anchor and chain. Mooring buoys may be 

placed near drilling rigs or platforms so that service vessels need not anchor or for when they cannot 

anchor (in deeper water). The temporarily installed anchors for these buoys would most likely be 

smaller and lighter than those used for vessel anchoring and, thus, would have less impact on the 

sea bottom. Moreover, installing one buoy would preclude the need for numerous individual vesselanchoring occasions. Service-vessel anchoring is assumed not to occur in water depths >150 m 

(492 ft) and only occasionally in shallower waters (vessels would always tie up to a platform or buoy 
3-36 Gulf of Mexico Multisale EIS

BOEM’s data indicate that the total area 

lost due to the presence of production 

platforms has historically been and 

would continue to be less than 1 percent 

of the total surface area available.

in water depths >150 m [492 ft]). Barges are assumed to tie up to a production system rather than 

anchor. Barges and other vessels are also used for both installing and removing structures. Barge 

vessels use anchors placed away from their location of work.

3.1.3.4.2 Space-Use Requirements

Leasing on the OCS results in operations that temporarily occupy sea bottom and water 

surface area for dedicated uses. The OCS oil- and gas-related operations include the deployment of 

seismic vessels, bottom surveys, and the installation of surface or subsurface bottom-founded 

production structures with anchor cables and safety zones. While in use, these areas would become 

unavailable to commercial fishermen, sand borrowing, or any other competing use.

The G&G surveys can occur in both shallow and deepwater areas. Usually, fishermen are 

precluded from a very small area for several days during active G&G surveying. Exploratory drilling 

rigs spend approximately 40-150 days onsite and are a short-term interference to commercial 

fishing. A major bottom-founded production platform in water depths less than 450 m (1,476 ft), with 

a surrounding 100-m (328-ft) navigational safety zone, requires approximately 6 ha (15 ac) of space. 

A bunkhouse structure needs about 4 ha (9 ac) and a satellite structure needs about 1.5 ha (3.7 ac) 

of space.

In water depths greater than 450 m (1,476 ft), 

production platforms would be compliant towers, 

floating production structures (such as TLPs and 

spars), and FPSOs. Even though production 

structures in deeper water are larger and individually 

would take up more space, there would be fewer of 

them compared with the great numbers of bottomfounded platforms in shallower water depths. Factoring in various configurations of navigational 

safety zones, deepwater facilities may require up to a 500-m (1,640-ft) radius safety zone or 78 ha 

(193 ac) of space (33 CFR § 147.15). Production structures in all water depths have a life 

expectancy of 20-30 years.

Alternative A*: A maximum of 648 ha (1,598 ac) could be lost to other uses under 

Alternative A. This number is based on a high of 108 production structures of approximately 6 ha 

(15 ac) of surface area operating simultaneously during the life of a proposed action. This is 

approximately 0.001 percent of the surface area of the Gulf of Mexico.

Alternative B*: A maximum of 546 ha (1,347 ac) could be lost to other uses under 

Alternative B. This number is based on a high of 91 production structures of approximately 6 ha 

(15 ac) of surface area operating simultaneously during the life of Alternative B. This is 

approximately 0.0008 percent of the surface area of the Gulf of Mexico.
Impact-Producing Factors and Scenario 3-37

Alternative C*: A maximum of 120 ha (296 ac) could be lost to other uses under 

Alternative C. This number is based on a high of 20 production structures of approximately 6 ha 

(15 ac) of surface area operating simultaneously during the life of Alternative C. This is 

approximately 0.0002 percent of the surface area of the Gulf of Mexico.

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

3.1.3.4.3 Structure Lighting

Light pollution in the GOM comes from OCS oil- and gas-related structures and service 

vessels and may increase visibility during night hours. The OCS oil- and gas-related structures in 

the GOM are illuminated from incandescent lights and from the glow of burning or flaring natural gas 

that cannot be stored or transported to shore. To assist in nighttime operations and aid navigation, 

manned platforms are generally well illuminated by exterior floodlights. Platforms generally have two 

varieties of floodlights: high-pressure sodium or mercury vapor. High-pressure sodium lights emit 

yellow-orange light, whereas mercury vapor lights emit a perceptually blue-white light. Some 

initiative has been taken to move toward downward facing lighting and green light. Although there 

are differences between platforms, floodlights located between 20 and 40 m (66 and 132 ft) above 

the water surface illuminate the structure and the surrounding water to a depth of at least 100-200 m 

(328-656 ft) and can often be observed several miles away from the platform (Keenan et al., 2007). 

Unmanned structures usually have minimal aid-to-navigation lights.

In addition to offshore lighting, coastal support infrastructure is also illuminated. Coastal 

infrastructure lighting may be specifically designed to emit horizontal or vertical light. Horizontal and 

near-horizontal light emittance increases the visibility of light sources from a distance and 

significantly increases the illuminated area, but it can also cause the encroachment of light into 

adjacent unlit areas. Light emitted horizontally or near-horizontally produces more sky glow than 

that emitted upward, and much more than light emitted downward (Gaston et al., 2012).

3.1.3.5 Workovers and Abandonments

Completed and producing wells may require periodic reentry that is designed to maintain or 

restore a desired flow rate. These procedures are referred to as a well “workover.” Workover 

operations are also carried out to evaluate or reevaluate a geologic formation or reservoir (including 

recompletion to another strata) or to permanently abandon a part or all of a well. Examples of 

workover operations are acidizing the perforated interval in the casing, plugging back, squeezing 

cement, milling out cement, jetting the well in with coiled tubing and nitrogen, and setting positive 

plugs to isolate hydrocarbon zones. Workovers on subsea completions require that a rig be moved 

on location to provide surface support. Workovers can take from 1 day to several months to 

complete depending on the complexity of the operations, with a median of 7 days. Current oil-field 

practices include preemptive procedures or treatments that reduce the number of workovers 

required for each well. On the basis of historical data, BOEM projects a producing well may expect 
3-38 Gulf of Mexico Multisale EIS

to have seven workovers or other well activities during its lifetime. Workover fluids are discussed in 

Chapter 3.1.5.1.3 below.

There are two types of well abandonment operations—temporary and permanent. An 

operator may temporarily abandon a well to (1) allow detailed analyses or additional delineation 

wells while deciding if a discovery is economically viable, (2) save the wellbore for a future sidetrack 

to a new geologic bottom-hole location, or (3) wait on design or construction of special production 

equipment or facilities. The operator must meet specific requirements to temporarily abandon a well. 

Permanent abandonment operations are undertaken when a wellbore is of no further use to the 

operator (i.e., the well is a dry hole or the well’s producible hydrocarbon resources have been 

depleted). During permanent abandonment operations, equipment is removed from the well, and 

specific intervals in the well that contain hydrocarbons are plugged with cement. A cement surface 

plug is also required for the abandoned wells. This serves as the final isolation component between 

the wellbore and the environment.

3.1.4 Transport

3.1.4.1 Pipelines

Pipelines are the primary method used to transport a variety of liquid and gaseous products 

between OCS production sites and onshore facilities around the GOM (Table 3-3). A mature 

pipeline network exists in the GOM to transport oil and gas production from the OCS to shore. 

There are currently 144 pipeline landfalls (pipelines that have at one time or another carried 

hydrocarbon product) in the Louisiana Coastal Area (LCA) (Smith, official communication, 2015). 

Included in this number of pipeline landfalls is a subset of 121 pipeline systems under the U.S. 

Department of Transportation’s (DOT) jurisdiction originating in Federal waters and terminating 

onshore or in Louisiana State waters (Smith, official communication, 2015; Table 3-4). There are 

14 OCS oil- and gas-related pipelines that transition into Texas State lands or that make landfall 

onshore, many of which switch back across this boundary. The BSEE and DOT share responsibility 

for pipeline regulation on the OCS in the transition between Federal and State waters. For more 

information on regulation and permitting of pipelines, refer to Appendix A.3. 

Table 3-3. Oil Transportation Scenario under Alternative A, B, or C.

Activity Alternative1 

Offshore Subareas (m)2

Totals3

0-60 60-200 200-800 800-

1,600

1,600-

2,400 >2,400

Percent Oil 

Piped4

A 72-94% 100% 100% 100% 100% 100-66% 99.8-90.0%

B 70-94% 100% 100% 100% 100% 100-50% 98.8-84.6%

C 100% 100% 100% 100% 100% 100% 100%

Percent Oil 

Barged

A 28-6% 0% 0% 0% 0% 0% 0.2%

B 30-6% 0% 0% 0% 0% 0% 0.2%

C 0% 0% 0% 0% 0% 0% 0%
Impact-Producing Factors and Scenario 3-39

Activity Alternative1 

Offshore Subareas (m)2

Totals3

0-60 60-200 200-800 800-

1,600

1,600-

2,400 >2,400

Percent 

Tankered5

A 0% 0% 0% 0% 0% 0-34% 0-9.8%

B 0% 0% 0% 0% 0% 0-50% 0-15.2%

C 0% 0% 0% 0% 0% 0% 0%

1 Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 4 percent. Refer to 

Chapter 2.2.2.4 for more information. Percentage values indicated here would not change. 2 Refer to Figure 3-1. 3 Subareas totals may not add up to the planning area total because of rounding.

4 100% of gas is assumed to be piped.

5 Tankering is forecasted to occur only in water depths >1,600 m.

Table 3-4. Existing Coastal Infrastructure Related to OCS Oil- and Gas-Related Activities in the Gulf 

of Mexico.

Infrastructure Texas Louisiana Mississippi Alabama Florida Total

Pipeline Landfalls1 14 122 3 5 0 144

Platform Fabrication Yards2 12 37 4 1 0 54

Shipyards2 32 64 9 18 14 137

Pipe Coating Facilities2 9 6 0 2 2 19

Supply Bases2 32 55 2 7 0 96

Ports2 11 14 3 1 5 34

Waste Disposal Facilities2 16 29 3 3 2 53

Natural Gas Storage Facilities2 13 8 0 1 0 22

Helicopter Hubs2 118 115 4 4 0 241

Pipeline Shore Facilities2 13 40 0 0 0 53

Barge Terminals2 110 122 6 6 8 252

Tanker Ports2 4 6 0 0 0 10

Gas Processing Plants2 39 44 1 13 1 98

Refineries3 20 16 3 3 0 42

Petrochemical Plants2 126 66 2 9 13 216

1 Source: Smith, 2015.

2 Source: Dismukes, 2011.

3 Source: USDOE, Energy Information Administration, 2015a.

Newer installation methods have allowed the pipeline infrastructure to extend farther into 

deep water. The gas pipeline supporting the Shell Stones FPSO is expected to be the deepest 

pipeline in the GOM at 2,900 m (9,500 ft). More than 500 pipelines reach water depths of 400 m 

(1,312 ft) or more, and over 400 of those pipelines reach water depths of 800 m (2,625 ft) or more. 

These technical challenges are described in more detail in Deepwater Gulf of Mexico 2006: 

America’s Expanding Frontier (USDOI, MMS, 2006).
3-40 Gulf of Mexico Multisale EIS

30 CFR § 250.1003

Pipelines greater than 8 5/8 inches in 

diameter and installed in water depths of 

less than 200 feet shall be buried to a 

depth of at least 3 feet unless they are 

located in pipeline congested areas or 

seismically active areas as determined 

by the Regional Supervisor.

Pipeline Installation and Maintenance

Pipelines constructed in water depths <200 ft 

(61 m) are potential snags for anchors and trawls and 

must be buried according to BSEE’s regulations. 

These pipelines account for 56 percent of the total 

pipeline length in Federal waters. The regulations also 

provide for the burial of any pipeline, regardless of 

size, if BSEE determines that the pipeline may 

constitute a hazard to other uses of the OCS; in the 

Gulf of Mexico, BSEE has determined that all pipelines 

installed in water depths <60 m (197 ft) must be 

buried. The purpose of these requirements is to reduce the movement of pipelines by high currents 

and storms, protect the pipeline from the external damage that could result from anchors and fishing 

gear, reduce the risk of fishing gear becoming snagged, and minimize interference with the 

operations of other users of the OCS. For lines >85

/8 in (22.9 cm) a waiver of the burial requirement 

may be requested and may be approved if the line is to be laid in an area where the character of the 

seafloor would allow the weight of the line to cause it to sink into the sediments (self-burial). For a 

pipeline that crosses a fairway or anchorage in Federal waters in depths ≤60 m (197 ft), any length 

of pipeline must be buried to a minimum depth of 10 ft (3 m) below mudline across a fairway and a 

minimum depth of 16 ft (5 m) below mudline across an anchorage area. Some operators voluntarily 

bury these pipelines deeper than the minimum.

The purposes of these requirements are to (1) reduce the movement of pipelines during high 

sea states by storm currents and waves, (2) protect the pipeline from the external damage that could 

result from anchors and fishing gear, (3) reduce the risk of fishing gear becoming snagged, and (4) 

minimize interference with the operations of other users of the OCS.

Where pipeline burial is necessary, a jetting sled would be used. Such sleds are mounted 

with high-pressure water jets and pulled along the seafloor behind the pipe-laying barge. The water 

jets are directed downward to dig a trench; the sled guides the pipeline into the trench. Such an 

apparatus can jet pipe at an average of 1.6 km/day (1.0 mi/day). The cross section of a typical jetted 

trench for the flowline bundles would be about 4 m2 (43 ft2

); for deeper burial when crossing a 

fairway, the cross section would be about 13 m2 (140 ft2

). The cross section of a typical jetted trench 

for the export and interconnecting export pipelines would be about 5 m2

; for a pipeline trench 

crossing a fairway, the cross section would be about 15 m2 (161 ft2

).

Jetting disperses sediments over the otherwise undisturbed water bottom that flanks the 

jetted trench. The area covered by settled sediment and the thickness of the settled sediment 

depends upon variations in bottom topography, sediment density, and currents. Newer installation 

methods have allowed the pipeline infrastructure to extend to deeper water.
Impact-Producing Factors and Scenario 3-41

The following information is discussed more thoroughly in this Agency’s Deepwater Gulf of 

Mexico 2006: America’s Expanding Frontier (USDOI, MMS, 2006). Pipeline installation activities in 

deepwater areas can be difficult both in terms of route selection and construction. Depending on the 

location, the sea-bottom surface can be extremely irregular and present engineering challenges 

(e.g., high hydrostatic pressure, cold temperatures, and darkness, as well as varying subsurface and 

bottom current velocities and directions). Rugged seafloor may cause terrain-induced pressures 

within the pipe that can be operationally problematic, as the oil must be pumped up and down steep 

slopes. An uneven seafloor could result in unacceptably long lengths of unsupported pipeline, 

referred to as “spanning,” which in turn could lead to pipe failure from bending stress early in the life 

of the line. It is important to identify areas where substantial lengths of pipeline may go 

unsupported. Accurate, high-resolution geophysical surveying becomes increasingly important in 

areas with irregular seafloor. Recent advances in surveying techniques have significantly improved 

the capabilities for accurately defining seafloor conditions, providing the resolution needed to 

determine areas where pipeline spans may occur. After analyzing survey data, the operator 

chooses a route that minimizes pipeline length and avoids areas of seafloor geologic structures and 

obstructions that might cause excessive pipe spanning, unstable seafloor, and potential benthic 

communities.

The BSEE’s minimum cathodic protection design criteria for pipeline external corrosion 

protection is 20 years. For the most part, pipelines have a designed life span greater than 20 years 

and, if needed, can be retrofitted to increase the life span (Chapter 3.1.6.1). Should a pipeline need 

to be replaced because of integrity issues, a replacement pipeline is installed or alternate routes are 

used to transport the products, or a combination of the two. Besides replacement because of 

integrity issues, a pipeline may also be required to be replaced as a result of storm or other 

damages. The BSEE estimates that the overall pipeline replacement over the past few years is 

about 1 percent of the total installed.

The greater pressures and colder temperatures in deep water present difficulties with respect 

to maintaining the flow of crude oil and gas through pipelines. Under these conditions, the physical 

and chemical characteristics of the produced hydrocarbons can lead to the accumulation of gas 

hydrate, paraffin, and other substances within the pipeline. These accumulations can restrict and 

eventually block flow if not successfully prevented and/or abated. There are physical (including 

“pigging” devices) and chemical techniques (e.g., methanol or ethylene glycol) that can be applied to 

manage these potential accumulations. Companies are continuously looking for and developing 

new technologies such as electrically and water-heated pipelines and burial of pipelines in 

deepwater for insulation purposes.

Long-distance transport of multiphase well-stream fluids can be achieved with an effectively 

insulated pipeline. There are several methods to achieve pipeline insulation: pipe-in-pipe systems, 

which included electrically and water-heated pipelines; pipe with insulating wrap material; and as 

previously mentioned, buried pipelines where the soils act as an insulator. The design of all of these 

systems seeks a balance between the high cost of the insulation, the intended operability of the 

system, and the acceptable risk level.
3-42 Gulf of Mexico Multisale EIS

BOEM projects that the majority of new pipelines constructed as a result of a proposed 

action would connect to the existing pipeline infrastructure. In the rare instance that a new pipeline to 

shore would need to be constructed, it would likely be because there are no existing pipelines 

reasonably close and because constructing a pipeline to shore is considered more cost effective, 

although it is highly unlikely for an operator to choose this contingency (Dismukes, official 

communication, 2011a). BOEM anticipates that pipelines from most of the new offshore production 

facilities would tie in to the existing pipeline infrastructure offshore or in State waters, which would 

result in few new pipeline landfalls. Refer to Chapter 3.1.4.1 for a further discussion of pipeline 

landfalls. Production from a regionwide proposed action would contribute to the capacity of existing 

and future pipelines and pipeline landfalls.

The length of new pipelines was estimated using the amount of production, the number of 

structures projected as a result of each alternative, and the location of the existing pipelines. The 

range in length of pipelines projected is because of the uncertainty of the location of new structures, 

which existing or proposed pipelines would be used, and where they tie in to existing lines. Many 

factors would affect the actual transport system, including company affiliations, amount of 

production, product type, and system capacity.

Alternative A*: BOEM projects 355-2,144 km (220-1,332 mi) of new pipelines under 

Alternative A (Table 3-2). About 16-25 percent of the new pipeline length would be in water 

depths <60 m (197 ft), requiring burial.

Alternative B*: BOEM projects 254-1,641 km (157-1,020 mi) of new pipelines under 

Alternative B (Table 3-2). About 15-24 percent of the new pipeline length would be in water 

depths <60 m (197 ft), requiring burial.

Alternative C*: BOEM projects 105-505 km (65-314 mi) of new pipelines under Alternative 

C (Table 3-2). About 19-26 percent of the new pipeline length would be in water depths <60 m 

(197 ft), requiring burial.

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

Pipeline Landfalls

The OCS oil- and gas-related pipelines nearshore and onshore may join pipelines carrying 

production from State waters or territories for transport to processing facilities or to distribution 

pipelines located farther inland. Oil and gas companies have a strong financial incentive to reduce 

costs by utilizing, to the fullest extent possible, the mature pipeline network that already exists in the 

GOM. Economies of scale are a factor in pipeline transportation; maximizing the amount of product 

moved through an already existing pipeline decreases the long-term average cost of production. 

Additional considerations include mitigation costs for any new wetland and environmental impacts 

and various landowner issues at the landfall point. Because of these strong incentives to move new 
Impact-Producing Factors and Scenario 3-43

production into existing systems and to avoid creating new landfalls, the 5-year moving average of 

new OCS pipeline landfalls has been below two per year since 1986. Over the last 15 years (1999-

2014), there has been an average of slightly over one new OCS pipeline landfall every 2 years 

(0.53 per year). Table 3-5 lists the OCS pipeline landfalls that have been installed since 1996. 

While no new pipelines landfalls have been installed in the last 5 years, pipeline landfalls have been 

approved during that time. To project the likely number of new OCS pipeline landfalls, BOEM 

examined the historical relationships between new pipeline landfalls and a variety of factors 

including platforms installed, oil and gas production, and the total number of new pipelines. Based 

on this examination, BOEM assumes that the majority of new Federal OCS oil and gas pipelines 

would connect to the existing pipelines in Federal and State waters and that very few would result in 

new pipeline landfalls.

Table 3-5. OCS Pipeline Landfalls Installed from 1996 to 2014.

Segment 

Number 

Year of 

Installation* Product Type Size (in) Company State

10631 1996 Oil 24 Equilon Pipeline Company LLC LA

12470 1996 Oil 24 Manta Ray Gathering Company LLC LA

11217 1997 Gas 30 Enbridge Offshore LA

11496 1997 Oil 12 ExxonMobil Pipeline Company LA

11952 2000 Oil 18-20 ExxonMobil Pipeline Company TX

14470 2004 Oil 10 Chevron USA Inc. LA

13972 2004 Oil 24 Manta Ray Gathering Company LLC TX

13987 2004 Oil 24 Manta Ray Gathering Company LLC TX

13534 2005 Oil 30 BP Pipelines (North America) LA

13534 2005 Oil 30 Mardi Gras Endymion Oil Pipeline 

Co. LA

17108 2007 Gas/Condensate 16 Stone Energy Corporation LA

17691 2009 Gas/Oil 8 Stone Energy Corporation LA

*Year when the initial hydrostatic test occurred.

Source: Smith, official communication, 2015.

Alternative A, B or C*: Up to one (i.e., 0-1) new pipeline landfall could result under 

Alternative A, B, or C.

*Alternative D is not expected to affect pipeline landfalls. Refer to Chapter 2.2.2.4 for 

more information.

3.1.4.2 Barges

The capacity of oil barges used offshore can range from 5,000 to 80,000 bbl. Barges 

transporting oil may remain offshore for as long as 1 week while collecting oil; each round trip is 

assumed to be 5 days.
3-44 Gulf of Mexico Multisale EIS

It is assumed that barging would continue to account for <1 percent of the oil transported for 

the entire OCS Program and for any single alternative. Table 3-3 provides the percentages of oil 

barged to shore by subarea for each alternative. The average amount of oil barged between 2010 

and 2014 was 0.2 percent annually.

The barging of oil from offshore facilities located in the GOM has been reduced substantially 

compared with the 2005 statistics. Barging continues to represent a very small portion of the total 

volume of oil being transported from the GOM to shore. In 2014, that portion was 0.08 percent of 

the total volume as compared with 0.13 percent in 2010. The total oil production from the Gulf of 

Mexico for 2013 was reduced by approximately 10 percent as compared with the oil production for 

2010.

The number of active barging systems has been reduced over time from approximately eight 

systems in 2005 to four systems in 2010 and has remained constant since then. In 2010, there were 

17 offshore locations that were approved to barge oil. In 2013, this number was reduced to eight 

offshore locations that were approved to barge oil. Of these locations, seven barged oil at some 

point during the years 2013-2014. The remaining location did not report any oil sales for the entire 

period of 2013-2014.

In 2013, all “active” offshore barging locations were located in the CPA. The locations east 

of the Mississippi River accounted for roughly 78 percent of the total barged volume. Likewise, the 

locations located west of the Mississippi River accounted for the remaining 22 percent.

3.1.4.3 Oil Tankers

The FPSOs store crude oil in tanks in the hull of the vessel and periodically offload the crude 

to shuttle tankers or oceangoing barges for transport to shore. The FPSOs are used to develop 

marginal oil fields or are used in areas remote from the existing OCS pipeline infrastructure, 

especially development in the Lower Eocene Wilcox trend (Walker Ridge leasing area) that is far 

from most existing pipeline networks. The FPSO systems are suitable for the light and intermediate 

oils of the GOM, as well as heavier oil, such as the heavy oil Brazil plans to produce offshore in deep 

water. The use of FPSOs and shuttle tankering are only projected in water depths >800 m (2,625 ft). 

Shuttle tankers are used to transport crude oil from FPSO production systems to Gulf Coast refinery 

ports or to offshore deepwater ports such as the Louisiana Offshore Oil Port. Shuttle tanker design 

and systems are in compliance with USCG regulations, the Jones Act, and OPA requirements. As 

such, shuttle tankers are required to be double hulled. In the Gulf, the maximum size of shuttle 

tankers is limited primarily by the 34- to 47-ft (10- to 14-m) water depths. Because of these depth 

limitations, shuttle tankers are likely to be 500,000-550,000 bbl in cargo capacity.

Offloading operations involve the arrival, positioning, and hook-up of a shuttle tanker to the

FPSO. Shuttle tankers can maintain their station during FPSO offloading operations using 

techniques that generally do not require anchoring. Offloading could occur at an average rate of 

50,000 bbl per hour. During the FPSO offloading procedure, the shuttle tanker would continue to 
Impact-Producing Factors and Scenario 3-45

operate its engines in an idle mode so that any necessary maneuvers of the vessel could be 

promptly executed. Safety features, such as marine break-away offloading hoses and emergency 

shut-off valves, would be incorporated in order to minimize the potential for, and size of, an oil spill. 

In addition, weather and sea-state limitations would be established to further ensure that hook-up 

and disconnect operations would not lead to accidental oil release. A vapor recovery system 

between the FPSO and shuttle tanker would be employed to minimize the release of fugitive 

emissions from cargo tanks during offloading operations.

Tankering related to FPSO systems in the GOM began in 2012 at the Cascade Chinook 

Project. For additional information on FPSOs, refer to Chapter 3.1.3.2. The production transported 

by shuttle tankers related to this FPSO system accounted for 2.2 percent of the total volume 

produced in the GOM during 2014. Forecasted tankering operations are presented in Table 3-3. 

During the production ramp up interval (the first 2 years of production operations), 8 offloads were 

made during the first 6 months followed by 15 offloads over the next year. During the 2nd full year of 

operation, 46 offloads were made. In the subsequent years of production, two shuttle tankers on a 

staggered schedule were predicted to perform one offload every week (52 trips a year). A second 

FPSO (Stones Project) in the GOM area (Walker Ridge) is under construction by Shell Offshore, Inc. 

and is anticipated to commence production in 2016. This facility is also scheduled to transport the 

produced liquid hydrocarbons by shuttle tankers.

To develop a scenario for analytical purposes, the following assumptions are made regarding 

future OCS oil transportation by shuttle tanker:

• advances in pipe-laying technology would keep pace with the expansion of the oil 

industry into the deeper waters of the Gulf beyond the continental slope;

• all produced gas would be piped;

• tankering would not occur from operations on the continental shelf;

• tankering would only take place from marginal fields or fields in areas remote 

from the existing OCS pipeline infrastructure; and

• maximum offloading frequency for an FPSO could be once every 3 days during 

peak production.

Alternative A*: BOEM projects 0-1 FPSO systems could result under Alternative A. The 

number of shuttle tanker trips to port in a given year is primarily a function of the FPSO production 

rate, the number of wells drilled, and the capacity of supporting shuttle tankers. Considering an 

FPSO operating at a peak production rate of 150,000 bbl/day, supported by shuttle tankers of 

500,000-bbl capacity, maximum offloading could occur once every 3.3 days. This would equate to 

a 54.75-MMbbl production with 110 offloading events and shuttle tanker transits to GOM coastal 

or offshore ports annually per FPSO.

Alternative B*: BOEM projects 0-1 FPSO systems would result under Alternative B. 

Because the FPSO projections are expected to occur in the CPA, a similar number of tanker trips 

would occur from an FPSO under Alternative B as would under Alternative A.
3-46 Gulf of Mexico Multisale EIS

Alternative C*: BOEM projects no FPSO systems would result under Alternative C 

because no FPSO activity is expected to occur in the WPA; thus, no tankering is projected to 

occur under Alternative C.

*Because FPSOs are not expected to occur in the same area as the sensitive topographic 

features, Alternative D is not expected to affect FPSO system development. Refer to Chapter 

2.2.2.4 for more information.

3.1.4.4 Service Vessels

Service vessels are one of the primary modes of transporting personnel between service 

bases and offshore platforms, drilling rigs, derrick barges, and pipeline construction barges. In 

addition to offshore personnel, service vessels carry cargo (i.e., freshwater, fuel, cement, barite, 

liquid drilling fluids, tubulars, equipment, and food) offshore. A trip is considered the transportation 

from a service base to an offshore site and back, in other words a round trip. Service vessels were 

evaluated for the following categories: wells (exploration and development drilling); plug and 

abandonment of wells; platform installation; platform operation; platform decommissioning; subsea 

installation; subsea removal; and pipeline installation. Other vessel operations, including G&G 

activity associated with a leasing event, is assumed to be covered in these estimates. Based on the 

model provided by Kaiser (2010), there were an average of 4.46 supply vessels needed per week 

during exploration and development drilling in shallow water and 6.4 supply vessels needed per 

week during exploration and development drilling in deep water. Drilling operations in shallow water 

takes less time (5.9 weeks) when compared with deepwater drilling (10 weeks). A platform in 

shallow water (<800 m; 2,624 ft) is estimated to require one vessel trip every 3.1 days over the 

production life. A platform in deep water (≥800 m; 2,624 ft) is estimated to require one vessel trip 

every 1.2 days over the production life. All trips are assumed to originate from the designated 

service base. The duration vessels service an operational platform was considered to be between 

11 and 31 years (low to high). Service-vessel operations are most closely tied to actual production 

activities. Visual representation of this can be seen in Figure 3-7. 

Alternative A*: Alternative A is estimated to generate 43,000-541,000 service-vessel trips

over the 50-year period (Table 3-2) or 860-10,820 trips annually. Table 3-6 indicates that over 

875,000 service-vessel trips occurred on Federal navigation channels, ports, and OCS-related 

waterways in 2012. The number of service-vessel trips projected annually for Alternative A would 

represent <2 percent of the total annual traffic on these OCS-related waterways.

Alternative B*: Alternative B is estimated to generate 38,000-452,000 service-vessel trips 

over the 50-year period (Table 3-2) or 760-9,040 trips annually. Table 3-6 indicates that over 

875,000 service-vessel trips occurred on Federal navigation channels, ports, and OCS-related 

waterways in 2012. The number of service-vessel trips projected annually for Alternative B would 

represent <2 percent of the total annual traffic on these OCS-related waterways.
Impact-Producing Factors and Scenario 3-47

Alternative C*: Alternative C is estimated to generate 30,000-88,500 service-vessel trips 

over the 50-year period (Table 3-2) or 600-1,770 trips annually. Table 3-6 indicates that over 

875,000 service-vessel trips occurred on Federal navigation channels, ports, and OCS-related 

waterways in 2012. The number of service-vessel trips projected annually for Alternative C would 

represent <1 percent of the total annual traffic on these OCS-related waterways.

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

3.1.4.5 Helicopters

Helicopters are one of the primary modes of transporting personnel between service bases 

and offshore platforms, drilling rigs, derrick barges, and pipeline construction barges. Helicopters 

are routinely used for normal crew changes and at other times to transport management and special 

service personnel to offshore exploration and production sites. In addition, equipment and supplies 

are sometimes transported. An operation is considered a roundtrip and includes takeoff and landing.

Deepwater operations require helicopters that travel farther and faster, carry more personnel, 

are all-weather capable, and have lower operating costs. Helicopter trips have been declining over 

the last 15 years. There are several issues that could be contributing to this decline, including 

competition with increasingly faster boats and the development of new technology such as subsea 

systems. These systems decrease the number of platforms and personnel needed offshore, 

therefore reducing the amount of transportation needed. Additionally, oil and gas companies are 

increasingly subcontracting all helicopter support to independent contractors who may use one fleet 

to service multiple oil and gas companies. The number of helicopters operating in the GOM is 

expected to decrease in the future, and helicopters that do operate are expected to be larger and 

faster. 

The scenarios for each alternative and the Cumulative OCS Oil and Gas Program scenarios 

(Chapter 3.3.1.7) below use the current level of activity as a basis for projecting future helicopter 

operations in relation to the production activity forecasted. The Federal Aviation Administration 

(FAA) regulates helicopter flight patterns. Because of noise concerns, FAA Circular 91-36C 

encourages pilots to maintain higher than minimum altitudes near noise sensitive areas. The 

Helicopter Safety Advisory Conference recommended practice states that helicopters should 

maintain a minimum altitude of 750 ft (229 m) while in transit offshore and a maximum of 500 ft 

(152 m) while working between platforms and drilling rigs (Helicopter Safety Advisory Conference, 

2010). When flying over land, the specified minimum altitude is 1,000 ft (305 m) over unpopulated 

areas and coastlines, and 2,000 ft (610 m) over populated areas and sensitive areas including 

national parks, recreational seashores, and wildlife refuges. In addition, guidelines and regulations 

issued by the NMFS under the authority of the Marine Mammal Protection Act include provisions 

specifying helicopter pilots to maintain an altitude of 1,000 ft (305 m) within 100 yd (91 m) of marine 

mammals.
3-48 Gulf of Mexico Multisale EIS

According to the Helicopter Safety Advisory Conference (2015), from 1996 to 2014, 

helicopter operations (take offs and landings) in support of regionwide OCS operations have 

averaged, annually, about 1.2 million operations, 2.7 million passengers, and 386,000 flight hours. 

There has been a decline in helicopter operations from 1,668,401 in 1996 to 741,201 in 2014

(Helicopter Safety Advisory Conference, 2015). Future projections are based on a high equal to the 

average number of flights over the last 15 years and a low equal to a continuing forecast of the 

current decline.

Alternative A*: There are 122,000-3,750,000 helicopter trips projected over the 50-year 

period for Alternative A (Table 3-2), or 2,440-75,000 trips annually.

Alternative B*: There are 105,000-3,415,000 helicopter trips projected over the 50-year 

period for Alternative B (Table 3-2), or 2,100-68,300 trips annually.

Alternative C*: There are 70,000-440,000 helicopter trips projected over the 50-year 

period for Alternative C (Table 3-2), or 1,400-8,800 trips annually.

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

3.1.4.6 Navigation Channels

BOEM conservatively estimates that there are approximately 4,850 km (3,013 mi) of Federal 

navigation channels, bayous, and rivers potentially exposed to OCS traffic regionwide (Table 3-6; 

Figure 3-8) and that the average canal is widening at a rate of 0.99 m/yr (3.25 ft/yr) (Thatcher et al., 

2011). This would result in a total (OCS and non-OCS oil- and gas-related) annual land loss of 

approximately 831 ac/yr (336 ha/yr). Total land loss in these areas can be caused by multiple 

factors, including saltwater intrusion, hurricanes, and vessel traffic (refer to Chapter 3.3.2.8 below). 

Assuming that vessel traffic alone was the sole source of erosion, the rate of land loss would be 

related to the usage of those canals by both OCS Program-related vessels and other vessel traffic. 

Using the estimated proportion of OCS Program vessel traffic as a measurement of erosion, the 

numbers above are considered conservative because open waterways were included in the total 

length of Federal navigation channels, vessel size was not taken into consideration, and there are 

sources of erosion to navigation canals other than vessel traffic alone.
Impact-Producing Factors and Scenario 3-49

Table 3-6. Waterway Length, Depth, Traffic, and Number of Trips for 2012.

Waterway

Canal 

Length 

(km)

Maintained Depth 

(ft)

Traffic (1,000 

short tons)

Number of Trips

Foreign Domestic

Gulf Intracoastal Waterway (GIWW)

Apalachee Bay to Panama City, FL 217 12 607 0 329

Panama City to Pensacola Bay, FL 177 12 1,610 0 1,114

Pensacola Bay, FL to Mobile Bay, 

AL 74 12 3,962 0 3,646

Mobile Bay, AL to New Orleans, LA 215 12, 14 18,209 0 13,585

Mississippi River, LA to Sabine River, 

TX 428 12, 10 63,911 0 52,435

Sabine River to Galveston, TX 135 12 59,577 0 33,113

Galveston to Corpus Christi, TX 305 11, 11, 10.2 29,314 0 21,178

Corpus Christi, TX to Mexican 

Border 214 10, 12, 7 1,920 0 1,483

Morgan City - Port Allen Route, LA 103 10 18,832 0 9,463

Florida Harbors, Channels, and Waterways

Escambia and Conecuh Rivers, FL 

and AL; Escambia Bay, FL 12 10 1,664 0 1,930

La Grange Bayou, FL 3 9 219 0 70

Panama City Harbor, FL 9 34, 32, 10 2,326 308 674

Pensacola Harbor, FL 21 35, 33, 15, 14 879 471 435

St. Marks River, FL 61 9 72 0 36

Tampa Harbor, FL 141 45, 43, 34, 12, 9 31,650 834 1,459

Port Manatee, FL 5 40 3,397 219 30

Alabama Harbors, Channels, and Waterways

Mobile Harbor, AL 71 47, 45, 40, 13-39 54,888 1,338 17,965

Theodore Ship Channel, AL 13 40 4,646 212 1,357

Mississippi Harbors, Channels, and Waterways

Biloxi Harbor, MS 39 12, 10, 12 1,047 0 1,106

Gulfport Harbor, MS 34 30, 32, 8 1,888 200 406

Pascagoula Harbor, MS 18 40, 38, 38, 22, 12 33,785 601 3,110

Bayou Casotte, MS 2 38 33,467 518 2,837

Louisiana Harbors, Channels, and Waterways

Atchafalaya River (Lower), LA 62 20 983 332 11,050

Barataria Bay Waterway, LA 66 17, 10 288 13 5,146

Bayou Lafourche and Bayou 

Lafourche-Jump Waterway 80 28, 27, 27, 9 6,092 2,342 16,463

Bayou Little Caillou, LA 56 12 68 0 305

Bayou Teche, LA 171 3,3,4,7 474 0 321

Bayou Teche and Vermilion River, 

LA 83 8,11,9,8,5 601 17 1,541
3-50 Gulf of Mexico Multisale EIS

Waterway

Canal 

Length 

(km)

Maintained Depth 

(ft)

Traffic (1,000 

short tons)

Number of Trips

Foreign Domestic

Bayou Terrebonne, LA 61 10 134 0 692

Calcasieu River and Pass, LA 176 42, 42, 41-42, 36, 12, 7 54,382 1,318 32,207

Freshwater Bayou, LA 34 12 493 57 4,989

Houma Navigation Canal, LA 59 16, 15, 16 473 30 1,812

Mermentau River, LA 131 4, 7, 12, 10, 10, 9, 11,

6, 8, 4, 4, 7 311 0 1,802

Mermentau River, Bayou Nezpique, 

and Des Cannes, LA 122 9, 14, 10 443 0 649

Mississippi River, Baton Rouge LA 

to the Mouth of Passes 437 45, 13 456,551 5,635 216,588

Port of New Orleans, LA 83 45, 30, 32, 36, 37, 12 79,342 1,852 26,820

Port of Baton Rouge, LA 144 45, 40, 9, 12 59,993 664 47,602

Port of South Louisiana 86 45 252,069 2,451 67,601

Port of Plaquemines, LA 131 45 58,280 654 74,951

Passes of the Mississippi River, LA 57 13, 45 230,048 5,635 3,707

Mississippi River Gulf Outlet via 

Venice Vicinity Consolidation 22 16, 14, 14 1,585 13 6,276

Petit Anse, Tigre, and Carlin 

Bayous 28 6, 9, 5, 7 1,563 0 1,243

Port of Iberia 14 13 ~2,200 NA NA

Port of Morgan City, LA – 12 1,771 202 12,474

Waterway from Empire, LA to the 

Gulf of Mexico 17 6,9,14 1,044 0 7,292

Waterway from Intracoastal 

Waterway 

to Bayou Dulac, LA

61 14 145 0 1,271

Texas Harbors, Channels and Waterways

Brazos Island Harbor, TX 47 36.5, 38, 31, 38, 12, 14, 

7 5,614 251 1,155

Cedar Bayou, TX 22 11 1,349 0 1,222

Channel to Aransas Pass, TX 11 14 782 20 749

Channel to Port Bolivar, TX 17 12 0 0 56,583

Corpus Christi Ship Channel, TX 64 47, 45, 46, 47, 14, 9 69,001 1,349 102,837

Dickenson Bayou, TX 34 9 47 0 25

Freeport Harbor, TX 14 44, 37, 18, 40 22,085 716 3,207

Galveston Channel, TX 6 41 11,618 2,843 61,016

Houston Ship Channel, TX 112 45, 40, 32-39, 9, 7, 35-

37, 7, 40, 12 238,186 6,262 81,048

Matagorda Ship Channel, TX 91 35, 9.8, 10, 12.8, 2 9,333 329 1,847

Sabine-Neches Waterway, TX 160 40, 37, 39, 32, 27, 20, 

9, 8 137,218 1,908 31,828
Impact-Producing Factors and Scenario 3-51

Waterway

Canal 

Length 

(km)

Maintained Depth 

(ft)

Traffic (1,000 

short tons)

Number of Trips

Foreign Domestic

Texas City Channel, TX 14 43, 41, 42, 42 57,758 776 6,625

Source: U.S. Dept. of the Army, COE, 2012.

Alternative A*: Assuming that vessel traffic alone was the sole source of erosion, there 

would be an annual loss of 0.40-5.02 ha (0.99-12.40 ac) for Alternative A. All service vessels 

associated with EPA blocks are assumed to use CPA navigational canals while inland and 

constitute less than 1 percent of the total vessel traffic. Service vessels associated with CPA 

leases are assumed to use CPA navigational canals and constitutes less than 2 percent of the 

total traffic. Service vessels associated with WPA leases are assumed to use WPA navigational 

canals and constitute less than 1 percent of the total traffic in the GOM.

Alternative B*: Assuming that vessel traffic alone was the sole source of erosion, there 

would be an annual loss of 0.46-5.53 ha (1.15-13.66 ac) for Alternative B.

Alternative C*: Assuming that vessel traffic alone was the sole source of erosion, there 

would be an annual loss of 0.18-0.54 ha (0.45-1.34 ac) for Alternative C.

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.
3-52 Gulf of Mexico Multisale EIS

Figure 3-8. Gulfwide OCS Oil- and Gas-Related Service Bases and Major Waterways.
Impact-Producing Factors and Scenario 3-53

3.1.5 Discharges and Wastes

3.1.5.1 Operational Wastes and Discharges Generated by OCS Oil- and Gas-Related 

Facilities

The primary operational wastes and discharges generated during offshore oil and gas 

exploration and development are drilling fluids, drill cuttings, various waters (e.g., bilge, ballast, fire, 

and cooling), deck drainage, sanitary wastes, and domestic wastes. During production activities, 

additional waste streams include produced water, produced sand, and well-treatment, workover, and 

completion fluids. Minor additional discharges occur from numerous sources. These discharges 

may include desalination unit discharges, blowout preventer fluids, boiler blowdown discharges, 

excess cement slurry, several fluids used in subsea production, and uncontaminated freshwater and 

saltwater.

Regulations

The Clean Water Act (CWA) establishes conditions and permitting for discharges of 

pollutants into the waters of the United States under the National Pollution Discharge Elimination 

System (NPDES) and gives the USEPA the authority to implement pollution control programs such 

as setting wastewater standards for industry and to set water quality standards for all contaminants 

in surface waters. Accordingly, the USEPA regulates all waste streams generated from OCS oiland gas-related activities through permits issued by the USEPA Region that has jurisdictional 

oversight.

The USEPA Region 4 has jurisdiction over the eastern portion of the Gulf of Mexico OCS, 

including all of the EPA and a portion of the CPA off the coasts of Alabama and Mississippi (Figure 

3-9). The USEPA Region 6 has jurisdiction over the rest of the CPA and all of the WPA. Each 

region issues general permits but can require an operator to apply for an individual permit. Each 

USEPA Region has promulgated general permits for discharges that incorporate the 1993 and 2000 

effluent guidelines (USEPA, 1993a and 2000b) for synthetic-based fluid (SBF)-wetted cuttings as a 

minimum. The permits are valid for 5 years. The current USEPA Region 4 general permit 

(GEG460000) was issued on March 15, 2010; became effective on April 1, 2010; and expired on 

March 31, 2015 (USEPA, 2010a). The renewal of the permit is being administratively continued for 

those operators who are already covered under the permit and request an extension. However, no 

new general permits will be granted until the permit is renewed. Operators may apply for an 

individual permit. The current Region 6 permit (GMG290000) was reissued with an effective date of 

October 1, 2012, expiring at midnight on. September 30, 2017 (USEPA, 2012a).
3-54 Gulf of Mexico Multisale EIS

Figure 3-9. Water Quality Jurisdictional Boundaries for USEPA Regions 4 and 6.

Permits issued under Section 402 (NPDES) of the CWA for offshore activities must comply 

with any applicable water quality standards and/or Federal water quality criteria, as well as Section 

403 (Ocean Discharge Criteria) of the CWA. Water quality standards consist of the waterbody’s 

designated uses, water quality criteria to protect those uses and to determine if they are being 

attained, and antidegradation policies to help protect high-quality waterbodies (refer to Chapter 4.2). 

Discharges from offshore activities near State water boundaries must comply with all applicable 

State water quality standards.

Section 403 of the CWA requires that NPDES permits for discharges to the territorial seas 

(baseline to 3 mi [5 km]), contiguous zone, and ocean be issued in compliance with USEPA’s 

regulations for preventing unreasonable degradation of the receiving waters. Prior to permit 

issuance, ocean discharges must be evaluated against the USEPA’s published criteria for 

determination of unreasonable degradation. Unreasonable degradation is defined in the NPDES 

regulations (40 CFR § 125.1211e) as the following:

• significant adverse changes in ecosystem diversity, productivity, and stability of 

the biological community within the area of discharge and surrounding biological 

communities;

• threat to human health through direct exposure to pollutants or through 

consumption of exposed aquatic organisms; and

• loss of aesthetic, recreational, scientific, or economic values, which is 

unreasonable in relation to the benefit derived from the discharge.
Impact-Producing Factors and Scenario 3-55

Compliance and Enforcement

U.S. Environmental Protection Agency

In order for a facility to be covered by a general NPDES permit, the operator must submit a 

notice of intent (NOI) to be covered by the general permit. Region 6 developed an “electronic NOI 

(eNOI)” system so that coverage is immediate (USEPA, 2015a). The USEPA evaluates NOIs on a 

case-by-case basis and reserves the right to deny coverage if it is determined the facility is ineligible 

or has falsified information. The NPDES permit sets minimum requirements that every allowable 

discharge must meet. If a waste does not meet the requirements of the permit, the permit would be 

considered violated and the USEPA could take an enforcement action. Discharges are monitored 

and the data are reported to the USEPA through discharge monitoring reports (DMRs). These 

reports must be turned in quarterly and contain all of the information required by the permit for that 

discharge. Region 6 now has an electronic Discharge Monitoring Report (DMR) system known as 

“NetDMR,” which is now required for all facilities covered by their general permit (USEPA, 2015b). 

Failure to submit any information or monitoring results required by the permit is considered a 

violation. Data from submitted NetDMRs populate the USEPA’s national Integrated Compliance 

Information System database. Region 6 reviews the Integrated Compliance Information System’s

data to identify facilities violating the permit conditions or reporting requirements. Violations are 

reviewed and enforcement actions are taken as deemed appropriate, particularly for serious single 

event violations, an ongoing pattern of noncompliance, or significant noncompliance (noncompliance 

for two running quarters or more). Depending on the type of violation, severity, length of violation, 

environmental damage, or illegal activity, the USEPA may request more information, issue a warning 

letter or order corrective actions, assess a penalty, or refer it to the U.S. Department of Justice or 

Criminal Investigation Division. The USEPA may use information, pictures, and other documentation 

from BSEE, BOEM, or the USCG to support its enforcement cases. The public may view violations 

and enforcement actions in the Enforcement and Compliance History Online database (USEPA, 

2015c), which is updated every 30 days from the Integrated Compliance Information System’s

database.

Bureau of Safety and Environmental Enforcement

In addition to facilities’ inspections in Federal waters in the Gulf of Mexico (refer to Chapter 

1.3.2), BSEE performs NPDES inspections on behalf of the USEPA for production platforms and 

drilling rigs through a 1984 Memorandum of Understanding between the U.S. Department of the 

Interior, the USEPA, and the U.S. Department of Transportation (USDOI, MMS, 1983) and a 1989 

Memorandum of Agreement between MMS (BSEE’s predecessor) and the USEPA Region 6 

(USDOI, MMS, 1989). According to the Memorandum of Agreement, BSEE inspects a maximum of 

50 OCS facilities per year for compliance with NPDES permit provisions. The Region 6 NPDES 

inspection responsibility officially transitioned from BSEE’s Districts to BSEE’s Environmental 

Enforcement Branch, Environmental Inspection and Enforcement Unit on September 18, 2014, in 

preparation for the 2015 inspection cycle (Sanders, official communication, 2015). The scope of 

those inspections does not include sampling. Coordination of a potential Memorandum of 

Agreement between BSEE and USEPA Region 4 concerning NPDES inspection needs is ongoing.
3-56 Gulf of Mexico Multisale EIS

Facility inspections are chosen on a variety of parameters such as pollution history, the 

USEPA’s reporting anomalies and errors, and general frequency for a lack of past inspection visits, 

among others. An inspection or audit may also be triggered by a major pollution release event 

triggering a rapid visit turnaround. The BSEE utilizes the U.S. Environmental Protection Agency’s 

ICIS database where DMRs are reported for the permitted features specific to the facility, and 

deviations and violations are noted. A thorough review of these data is included and evaluated for 

every inspection. When completed, an inspection report is prepared and sent to the USEPA where 

the noncompliances observed during the inspection are summarized and formally referred to them 

for support of potential further enforcement action. If violations or concerns are observed during the 

inspection, as per any of BSEE regulations from 30 CFR parts 200-699, then BSEE-driven incidents 

of noncompliance are prepared and sent directly to the offending facility, and the USEPA is copied 

as a courtesy.

Pollution-related incidents of noncompliance are shown in Table 3-7. The BSEE posts some 

incidents of noncompliance on its website (USDOI, BSEE, 2015a), but as BSEE is working to 

improve its website postings, additional information can be requested through BSEE’s Freedom of 

Information Act office. Over 700 NPDES inspections were performed between 1999 and 2014 

(Table 3-8).

Table 3-7. Pollution-Related Incidents of Noncompliance Issued from 1986 to the Present.

INC Number INC Description

Approximate 

Number of INCs 

Issued

E-100 The operator failed to prevent unauthorized discharge 

of pollutants into offshore waters. 2,035

E-101 The lessee failed to dispose of drill cuttings, sand, and 

other well solids as approved. 18

E-102

Facility is not equipped with curbs, gutters, drip pans,

and drains necessary to collect all contaminants not 

authorized for discharge.

1,331

E-103

The sump system does not automatically maintain the 

oil at a level sufficient to prevent discharge of oil into 

offshore waters.

1,054

E-104

All hydrocarbon handling equipment for testing and 

production is not designed, installed, and operated to 

prevent pollution.

43

E-105

All gravity drains are not equipped with a water trap or

other means to prevent gas in the sump system from 

escaping through the drains.

194

E-106 Sump piles are used as processing devices. 48

E-107

The lessee failed to adhere to the prohibition on the 

addition of petroleum-based substances to the mud 

system without prior approval of the district manager.

2 

E-108

The lessee failed to prevent the disposal of equipment,

cables, chains, containers, or other materials into 

offshore waters.

49

Source: USDOI, BSEE, 2011.
Impact-Producing Factors and Scenario 3-57

Drilling fluids used on the OCS are 

divided into two categories: water based 

(WBFs) and nonaqueous based (OBFs 

or SBFs).

Table 3-8. National Pollutant Discharge Elimination System Inspections from 

1999 through 2014.

Calendar 

Year

Number of Platforms 

Inspected

Number of Rigs 

Inspected Annual Totals

1999 34 16 50

2000 76 15 91

2001 40 12 52

2002 39 18 57

2003 30 10 40

2004 16 7 23

2005 22 11 33

2006 20 12 32

2007 25 4 29

2008 30 20 50

2009 26 23 49

2010 17 12 29

2011 18 21 39

2012 30 24 54

2013 37 32 69

2014 16 14 30

Total 476 251 727

(1) Data as of February 4, 2015.

(2) Inspections performed by the Minerals Management Service; Bureau of

Ocean Energy Management, Regulation and Enforcement; and Bureau of

Safety and Environmental Enforcement.

Drilling Muds and Cuttings

Drilling fluids (also known as drilling muds) and cuttings represent a large quantity of the 

discharge generated by drilling operations. Drilling fluids are used in rotary drilling to remove 

cuttings from beneath the bit, to control well pressure, to cool and lubricate the drill string and its bit, 

and to seal the well. Drill cuttings are the fragments of rock generated during drilling and carried to 

the surface with the drilling fluid. Drilling discharges of muds and cuttings are regulated by the 

USEPA through the NPDES permitting process.

The composition of drilling fluids is complex. 

Drill cuttings are a different grain size and 

composition from the existing surface sediments. 

Drilling fluids used on the OCS are divided into two 

categories: water based and nonaqueous based. 

Water-based fluids (WBFs) have a water soluble 

continuous phase while nonaqueous-based fluids have a continuous phase that is not soluble in 

water. The base fluid can be freshwater or saltwater in WBFs, mineral or diesel oil-based fluids 

(OBFs), or synthetic-based fluids (SBFs). Thus, both OBFs and SBFs are nonaqueous-based fluids. 
3-58 Gulf of Mexico Multisale EIS

Clays, barite, and other chemicals are added to the base fluid to improve the performance of the 

drilling fluid (Boehm et al., 2001).

On the OCS, the WBFs have been used for decades in drilling. In the GOM, they are the 

most commonly used drilling fluids for exploration and production wells. The discharge of WBFs and 

cuttings associated with WBFs is allowed on the OCS under the general NPDES permits issued by 

USEPA Regions 4 and 6, as long as the discharge meets the conditions required in the permit. 

Discharge of WBFs results in increased turbidity in the water column, alteration of sediment 

characteristics because of coarse material in cuttings, and the input of trace metal into the 

environment. Occasionally, formation oil may be discharged with the cuttings, adding hydrocarbons 

to the discharge. However, as noted in the NPDES permits, no free oil shall be discharged; static 

sheen tests must be performed once per week when discharging. In shallow environments, WBFs 

are rapidly dispersed in the water column immediately after discharge and rapidly descend to the 

seafloor (Neff, 1987). In deep waters, fluids dispersed near the water surface would disperse over a 

wider area than fluids dispersed in shallow waters.

The early nonaqueous drilling fluids, termed oil-based drilling fluids (OBF), were occasionally 

used for directional drilling and in drill-bore sections where additional lubricity was needed. Crude, 

diesel, and mineral oil were used. Diesel OBFs contains light aromatics such as benzene, toluene, 

and xylene. Mineral oil is advantageous over diesel because it is less toxic. Hydrocarbon 

concentration and impacts to benthic community diversity and abundance have been observed 

within 200 m (656 ft) of the drill site with diminishing impacts measured to a distance of 2,000 m 

(6,562 ft) (Neff, 1987). All OBFs and associated cuttings must be transported to shore for recycling 

or disposal unless reinjected. Due to the environmental concerns of OBFs, SBFs were created in 

the 1990s (Bakhtyar and Gagnon, 2012). The OBFs are rarely used because of the many 

advantages of SBFs. The SBFs are manufactured hydrocarbons. The SBF mud system also 

contains additives such as emulsifiers, clays, wetting agents, thinners, and barite. Since the SBFs 

are not petroleum based, they do not contain the aromatic hydrocarbons and polycyclic aromatic 

hydrocarbons (PAH) that contributed to OBF toxicity and persistence on the seafloor (Bakhtyar and 

Gagnon, 2012). In fact, SBFs have several additional advantages over OBFs, which include that 

they are well characterized, have lower toxicity and bioaccumulation potentials, and biodegrade 

faster. Since 1992, SBFs have been increasingly used, especially in deep water, because they 

perform better than WBFs and OBFs. The SBFs reduce drilling times and costs incurred from 

expensive drilling rigs. By 1999, about 75 percent of all wells drilled in waters deeper than 305 m 

(1,000 ft) were drilled with SBFs in the Gulf of Mexico (CSA, 2004). Although there are many types 

of SBFs, esters, internal olefins, and linear alpha olefins are most commonly used in the GOM.

A literature review (Neff et al., 2000) discussed knowledge about the fate and effects of 

SBFs discharges on the seabed. Like OBFs, the SBFs are hydrophobic, meaning they are not 

soluble in the water column and therefore are not expected to adversely affect water quality. The 

SBF-wetted cuttings settle close to the discharge point and affect the local sediments. Cuttings piles 

with a maximum depth of 8-10 in (20-25 cm) were noted in a seabed study of shelf and slope 

locations where cuttings drilled with SBF were discharged. The SBF discharge can alter sediment 
Impact-Producing Factors and Scenario 3-59

grain size and add organic matter, which can result in localized anoxia while SBF degrades (Melton 

et al., 2004). Different formulations of SBFs use base fluids that degrade at different rates, thus 

affecting the duration of the impact. Esters and olefins are the most rapidly biodegraded SBFs. 

Ongoing research is aimed at understanding the relationships between the chemical structure in 

SBFs and the environmental fates and effects, which would provide the design basis for fluids with 

better environmental performance. For example, recent testing showed that less branching of alpha 

and internal olefins positively impacted both sediment toxicity and anaerobic biodegradation (Dorn 

et al., 2011).

Bioaccumulation tests indicate that SBFs and their degradation products should not 

bioaccumulate (Neff et al., 2000). In a study to measure degradation rates of SBFs on the seafloor, 

biodegradation proceeded after a lag period of up to 28 weeks, which was influenced by both the 

SBF type and prior exposure of the sediments to SBFs (Roberts and Nguyen, 2006). Sediment 

sulfate depletion due to microbial activity coincided with SBF degradation. Decreased SBF 

concentrations indicated that recovery in sediments occurred in the year between sample 

collections. Deposited cuttings and measurable sediment effects indicative of organic enrichment 

were concentrated within a distance of 250 m (820 ft) in both shelf and slope sites (CSA, 2004).

The discharge of the base SBF drilling fluid is prohibited. The SBFs and cuttings must meet 

environmental requirements. Both USEPA Regions 4 and 6 permit the discharge of cuttings wetted 

with SBF as long as the retained SBF amount is below a prescribed percent, meets biodegradation 

and toxicity requirements, and is not contaminated with the formation oil or PAH.

Typically, the upper portion of the well is drilled with WBF and the remainder is drilled with 

SBF. The upper sections would be drilled with a large diameter bit; progressively smaller drill bits 

are used with increasing depth. Therefore, the volume of cuttings per interval (length of wellbore) in 

the upper section of the well would be greater than the volume generated in the deeper sections.

Barite, a barium sulfate (BaSO4) mineral, is used as a weighting agent to increase the 

hydrostatic pressure of drilling muds in order to control high-pressure zones encountered during 

drilling. Because barite is also soft, it does not erode equipment but instead acts essentially as a 

lubricant (Mills, 2006). Additionally, barite is inert and does not react with other additives in the 

drilling fluid. Because of barite’s useful qualities, barite is a major component of all types of drilling 

fluid, but its use has somewhat declined due to advances in synthetic-based mud formulations and 

drilling technology. A study of 81 wells noted that, from 1998 to 2002, the quantity of barite 

discharged for a shallow well (2,936 m; 9,634 ft average) to a deep well (5,140 m; 16,864 ft average) 

is 110 tons barite per well and 586 tons barite per well, respectively (Candler and Primeaux, 2003).

Since barite is a natural mineral, it can have natural impurities associated with it. The 

impurities of concern in barite are trace metals such as mercury (Hg), cadmium (Cd), copper (Cu), 

zinc (Zn), and lead (Pb) that are often found in other mineral phases that were formed on or in the 

barite mineral deposit (Crecelius et al., 2007). However, the American Petroleum Institute (API) has 

set specifications for the barite used in the oil industry, which includes that the amount of water-
3-60 Gulf of Mexico Multisale EIS

soluble alkaline earth metals must be below 250 milligrams/kilogram (parts per million [ppm]) (Mills, 

2006). More importantly, since 1993, the USEPA has required the concentrations of Hg and Cd to 

be less than or equal to 1 ppm and 3 ppm, respectively, in the stock barite used to make up drilling 

muds (USEPA, 1993a and 2000b). Through Hg and Cd regulation, the USEPA can also control 

levels of other trace metals in barite. This reduces the addition of Hg to sediments to values similar 

to the concentration of mercury found in marine sediments throughout the GOM (Neff, 2002). 

Furthermore, barite is nearly insoluble in seawater, which means that it remains in the solid form 

where it is not readily available to biota unless the mineral particles themselves are directly digested.

Despite atmospheric mercury deposition being considered the main source of anthropogenic 

Hg inputs into the marine environment, the availability of Hg in barite was studied to confirm that 

barite in drilling muds was not a significant or available source of Hg in the marine environment. 

Crecelius et al. (2007) studied the solubility of barite and the rate at which it dissolves (and thereby 

releases associated metals such as Hg from the solid phase into the aqueous phase), the amount of 

metals released from barite, and the rate of dissolution of barite and release of metals after burial 

under simulated seafloor conditions. The research used three grades of barite: one commercially 

available barite ore used in drilling fluids, which meets the USEPA’s trace metal criteria; and two 

grades of barite to represent those used in the GOM prior to the 1993 USEPA regulation enacted to 

reduce the concentrations of Hg and Cd in drilling fluid. During a 1-week exposure of barite in 

seawater, in the pH range of 7.3 to 8.3, <1 percent of the Hg dissolved from the barite. The studies 

conducted at varying pH levels to mimic digestive tract conditions showed that very little (<0.1%) of 

the Hg in barite became available within 48 hours. When barite is added to anoxic sediments, the 

concentrations of methylmercury (methyl-Hg) and Hg were not elevated as compared with the same 

anoxic sediment without the addition of barite.

Crecelius et al. (2007) confirmed that trace metal contaminants in barite were in sulfide 

mineral inclusions dispersed within the barite matrix. In seawater with a pH of 7.3 to 8.3 over the 

period of 1 week, <1 percent of the Cu and Pb, 3 percent of the Zn, and 15 percent of the Cd 

dissolved from the inclusions within the barite. Thus, a small amount of these metals are soluble in 

seawater at this pH range. Since low-metal barite (barite that meets current USEPA standards) 

releases little of these metals to seawater, low-metal barite is not likely to cause environmental 

effects to organisms living in the water column. However, in acidic conditions simulating the gut of 

deposit-feeding benthic animals, a major portion of the Cd, Cu, Pb, and Zn are soluble, and 

<1 percent of the barium (Ba) are soluble in 48 hours.

In addition to laboratory studies, field studies have also been conducted to examine the role 

that barite plays in sediment Hg levels. Concentrations of total mercury in uncontaminated estuarine 

and marine sediments generally are 0.2 micrograms/gram (μg/g) dry weight or lower. Surface 

sediments collected 20-2,000 m (66-6,562 ft) away from four oil production platforms in the 

northwestern GOM contained 0.044-0.12 μg/g total mercury. These amounts are essentially 

background concentrations for mercury in surficial sediments on the Gulf of Mexico OCS (Neff, 

2002). A comparative study of surface and subsurface sediment samples from six offshore drill 

locations showed higher levels of total mercury found in the sediments closest to the drilling sites as 
Impact-Producing Factors and Scenario 3-61

compared with the sites greater than 3 km (1.9 mi) distant. Higher total mercury concentrations 

corresponded to higher barium concentrations also present. Higher total mercury levels in nearfield 

sediments did not translate to higher methyl-Hg concentration in those sediments, with a few 

exceptions (Trefry et al., 2007). Sediment redox conditions and organic content influence 

methylmercury formation. For more information on sediment and water quality, refer to Chapter 4.2. 

3.1.5.1.1 Produced Waters

Produced water is brought up from the hydrocarbon-bearing strata along with produced oil 

and gas. This waste stream can include formation water; injection water; well-treatment, completion, 

and workover compounds added downhole (including flowback water); and compounds used during 

the oil and water separation process. Formation water (brine) originates in the permeable 

sedimentary rock strata and is brought up to the surface commingled with the oil and gas. Injection 

water is water that was injected to enhance oil production and is used in secondary oil recovery. 

Flowback fluid (or water) is fluid that has been returned uphole after being injected into the formation 

for stimulation purposes. This includes water and chemicals used for hydraulic fracturing practices, 

as that would be considered a stimulation practice; fracture pack or “frac packs” are often used in the 

Gulf of Mexico during the completion process to clean and stimulate the area around the wellbore as 

well as for sand control (refer to Chapter 3.1.3.1 for more information on hydraulic fracturing 

processes used offshore in the Gulf of Mexico).

In addition to the added chemical products, produced water contains chemicals that have 

dissolved into the water from the geological formation where the water was stored. The amount of 

dissolved solids can be more concentrated than is found in seawater. Produced water contains 

inorganic and organic chemicals and radionuclides (226Ra and 228Ra). The composition of the 

discharge can vary greatly in the amounts of organic and inorganic compounds.

Both USEPA Region 4 and Region 6 general permits allow the discharge of produced water 

on the OCS provided that they meet discharge criteria. The produced water is treated to separate 

free oil from the water. Since the oil and water separation process does not completely separate all 

of the oil, some hydrocarbons remain with the produced water and often the water is treated to 

prevent the formation of sheen. Produced water may be discharged if the oil and grease 

concentration does not exceed 42 milligrams per liter (mg/L) daily maximum or 29 mg/L monthly 

average. The discharge must also be tested for toxicity. Both USEPA Region 4 and Region 6 

permits require no discharge within 1,000 m (3,281 ft) of an area of biological concern. Region 4 

also requires no discharge within 1,000 m (3,281 ft) of any federally designated dredged material 

ocean disposal site.

As noted above, completion fluids, including fluids from fracture packs or “frac-packs,” not 

returned to the deck of the platform during the completion job may be co-mingled and discharged 

with produced water if they meet the conditions of the appropriate NPDES permit. However, if the 

fluid composition is not compatible with the production system, the operator may decide to separate 

the returning well fluids from the production fluids and treat the fluids in temporary treatment systems 
3-62 Gulf of Mexico Multisale EIS

or collect the fluids for onshore disposal depending upon logistics (e.g., treatability of well fluid, 

volume of fluid, personnel limitations, treatment unit capacity, space on deck, weather, etc.).

The USEPA Region 6 NPDES permit required participation in the Produced Water Hypoxia 

Study, in which produced water was collected from 50 platforms that discharge into the hypoxic zone 

and analyzed for oxygen-demanding characteristics (Veil et al., 2005; Rabalais, 2005). The mean 

biochemical oxygen demand was 957 mg/L, total organic carbon was 564 mg/L, and total Kjeldahl 

nitrogen was 83 mg/L in produced waters from the platforms located within the hypoxic zone. 

Samples from platforms that produced mostly gas had higher average biological oxygen demand 

and total organic carbon concentrations but smaller volumes than platforms that produced mostly oil. 

About 508,000 bbl/day produced water was generated per day in the hypoxic zone in 2003. The 

estimated biological oxygen demand loading is 104,000 lb/day. In comparison to loadings from the 

Mississippi and Atchafalaya Rivers, the total nitrogen loading from produced water is about 

0.16 percent and total phosphorus loading is about 0.013 percent of the nutrient loading coming from 

the rivers. For more information on hypoxia and water quality in the Gulf of Mexico, refer to 

Chapters 3.3.2.12 and 4.2. 

Estimates of the volume of produced water generated per well vary because the percent of 

water is related to well age and hydrocarbon type. Usually, produced-water volumes are small 

during the initial production phase and increases over time as the formation approaches 

hydrocarbon depletion. Produced-water volumes range from 2 to 150,000 bbl/day (USEPA, 1993a). 

In some cases, a centralized platform is used to process water from several surrounding platforms. 

Some of the produced water may be reinjected into the well. Reinjection occurs when the produced 

water does not meet discharge criteria or when the water is used as part of operations. However, 

the vast majority of produced water is discharged per the conditions of the relevant U.S. 

Environmental Protection Agency NPDES permit. For example, in 2007, 48,673,102 bbl were used 

for enhanced recovery purposes, 1,298,417 bbl of produced water were reinjected, and 

537,352,846 bbl were discharged after treatment (Clark and Veil, 2009). In 2012, of a total 

produced-water volume of 509,159,846 bbl, 52,043,434 bbl were injected while an estimate of 

457,116,412 bbl were discharged (Veil, 2015).

BOEM maintains records of the volume of water produced 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 

3-9. The total volume for all water depths during this 15-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 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 3-9). The low-temperature and 

high-pressure conditions found in deeper water can result in flow problems such as hydrate 
Impact-Producing Factors and Scenario 3-63

formation in the lines. Additional quantities of chemicals are used to assure production, and even 

with recovery systems, some of these chemicals will be present in produced water (USDOI, MMS, 

2000a). For deepwater operations, new technologies are being developed that may discharge or 

reinject produced water at the seafloor or at “minimal surface structures” before the production 

stream is transported by pipeline to the host production facility.

Table 3-9. 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 344.6 180.4 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 1.8 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 60.1 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 20.0 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 0.9 485.6

Source: Gonzales, official communication, 2015.

3.1.5.1.2 Well-Treatment, Workover, and Completion Fluids

Wells are drilled using a base fluid and a combination of other chemicals to aid in the drilling 

process. Fluids (drilling muds) present in the borehole can damage the geologic formation in the 

producing zone. Completion fluids are used to displace the drilling fluid and protect formation 

permeability. “Clear” fluids consist of brines made from seawater mixed with calcium chloride, 

calcium bromide, and/or zinc bromide. These salts can be adjusted to increase or decrease the 

density of the brine to hold back-pressure on the formation. Additives, such as defoamers and 

corrosion inhibitors, are used to reduce problems associated with the completion fluids. Recovered 

completion fluids can be recycled for reuse.

Workover fluids are used to maintain or improve existing well conditions and production rates 

on wells that have been in production. Workover operations include casing and subsurface 

equipment repairs, re-perforation, acidizing, and stimulating via hydraulic fracturing. In the Gulf of 

Mexico, the type of hydraulic fracturing commonly used are fracture-pack or “frac packs” (refer to 

Chapter 3.1.3.1 for more information on these processes). During some of the workover operations, 

the producing formation may be exposed, in which case fluids like the aforementioned completion 

fluids are used. In other cases, such as acidizing and hydraulic fracturing, including “frac-packs” 
3-64 Gulf of Mexico Multisale EIS

(also considered stimulation or well treatment), hydrochloric and other acids are used. Both 

procedures are used to increase the permeability of the formation. The acids dissolve limestone, 

sandstone, and other deposits. Because of the corrosive nature of acids, particularly when hot, 

corrosion inhibitors are added. Since the fluids are altered with use, they are not recovered and 

recycled; however, these products may be mixed with the produced water and disposed of as 

described in Chapter 3.1.5.1.2 above.

Production treatment fluids are chemicals applied during the oil and gas extraction process. 

Production chemicals are used to dehydrate produced oil or treat the associated produced water for 

reuse or disposal. A wide variety of chemicals are used, including corrosion and scale inhibitors, 

bactericides, paraffin solvents, demulsifiers, foamers, defoamers, and water treatment chemicals 

(Boehm et al., 2001). Some of the production chemicals mix with the production stream and are 

transported to shore with the product. Other chemicals mix with the produced water. Most produced 

water cannot be discharged without some chemical treatment. Even water that is reinjected 

downhole must be cleaned to protect equipment. The types and volumes of chemicals that are used 

changes during the life of the well. In the early stages, defoamers are used. In the later stages, 

when more water than oil is produced, demulsifiers and water-treatment chemicals are used more 

extensively.

Boehm et al. (2001) discusses completion, stimulation, and workover chemicals that are 

used in the Gulf of Mexico. These same chemicals are used for fracturing, including “frac packs,” 

gravel packs, and acidizing processes. The report lists and defines the types of chemicals used as 

well as providing examples for each category of chemical (Boehm et al. (2001), Table 3). BOEM 

has included an update to this study in their 2015-2017 Studies Development Plan 

(http://www.boem.gov/Environmental-Studies-Planning/). After the fluids used for fracturing have 

performed their desired function, they are disposed of in the same manner as completion fluids or 

may be combined with the produced water. If the fluids return topside as a part of the completion 

job, they are considered waste completion fluids and would be disposed of as such. After the 

completion job is finished, the fluid is removed from the tubing in the well in order to begin producing 

hydrocarbons; this fluid may be comingled with the produced water and discharged per the 

requirements for produced water.

Both USEPA Regions 4 and 6 allow the discharge of well-treatment, completion, and 

workover fluids if they meet the condition of the NPDES permits. Both USEPA Regions 4 and 6 

prohibit the discharge of well-treatment, completion, and workover fluid with additives containing 

priority pollutants (e.g., benzene, toluene, lead, and mercury; the full list of priority pollutants can be 

found in Appendix A of 40 CFR part 423). Additives containing priority pollutants must be monitored. 

Some well-treatment, workover, and completion chemicals are discharged with the drilling muds and 

cuttings or with the produced-water streams. These discharges must meet the general toxicity limits 

in the NPDES general permit. Discharge and monitoring records must be kept.
Impact-Producing Factors and Scenario 3-65

3.1.5.1.3 Production Solids and Equipment

As defined by the USEPA in the discharge guidelines (Federal Register, 1993), produced 

sands are slurried particles, which surface from hydraulic fracturing, and the accumulated formation 

sands and other particles including scale, which is generated during production. This waste stream 

also includes sludges generated in the produced-water treatment system, such as tank bottoms from 

oil/water separators and solids removed in filtration. The guidelines do not permit the discharge of 

produced sand, which must be transported to shore and disposed of as nonhazardous oil-field waste 

according to State regulations. Estimates of total produced sand expected from a platform are from 

0 to 35 bbl/day according to the USEPA (1993). A variety of solid wastes are generated, including 

construction/demolition debris, garbage, and industrial solid waste. No equipment or solid waste 

from a facility may be disposed of in marine waters.

3.1.5.1.4 Bilge, Ballast, and Fire Water

Bilge, ballast, and fire water all constitute minor discharges generated by offshore oil and gas 

production activities, which are allowed to be discharged to the ocean, as long as the USEPA’s 

guidelines are followed. Uncontaminated bilge and ballast water are included in the miscellaneous 

discharges category of the USEPA Region 4 and Region 6 general permits (USEPA 2010 and 

2012). Ballast water is untreated seawater that is taken on board a vessel to maintain stability. 

Ballast water contained in segregated ballast tanks never comes into contact with either cargo oil or 

fuel oil. Newly designed and constructed floating storage platforms use permanent ballast tanks, in 

which the ballast in those tanks rarely becomes contaminated. Bilge water is seawater that 

becomes contaminated with oil and grease and with solids such as rust when it collects at low points 

in the facility. With the right equipment on board, dirty bilge and ballast water can be processed in a 

way that separates most of the oil from the water before it is discharged into the sea (USEPA, 

1993a). The discharge of any oil or oily mixtures is prohibited under 33 CFR § 151.10. The USEPA 

requires monitoring for visual sheen related to miscellaneous discharges, such as bilge and ballast 

water.

Offshore drilling rigs and the offshore production facilities used to process oil have special 

fire protection requirements. Fire water is defined in the USEPA Region 4 and Region 6 general 

permits as excess seawater or freshwater that permits the continuous operation of fire control 

pumps, as well as water released during training of personnel in fire protection. Fire control system 

test water is seawater, sometimes treated with a biocide that is used as test water for the fire control 

system on offshore platforms. This test water is discharged directly to the sea as a separate waste 

stream (USEPA, 1993a). As well, fire protection can also include a barrier of water that is 

sometimes used during flaring to provide protection between flaring systems and personnel, 

equipment, and facilities. The USEPA Region 4 and Region 6 general permits allow for the 

discharge of fire water that meets their specified limitations. The requirements include regulations 

and monitoring for treatment chemicals, discharge rate, free oil, and toxicity.
3-66 Gulf of Mexico Multisale EIS

3.1.5.1.5 Cooling Water

Cooling water is defined as water used for contact or noncontact cooling, including water 

used for equipment cooling, evaporative cooling tower makeup, and dilution of effluent heat content. 

Seawater is drawn through an intake structure on the drilling rig, ship, or platform to cool power 

generators and other machinery, and produced oil or water. Drillship cooling water structures have 

been noted to intake 16-20 million gallons/day while semisubmersibles have been noted to intake 

2 to over 10 million gallons/day from a water depth >400 ft (122 m) from the water’s surface 

(USEPA, 2006). However, newer semisubmersible units were noted to have an intake capacity of 

35 million gallons per day. Not all intake water is necessarily used as cooling water; some may be 

use for ballast water, cleaning, firewater, and testing. Organisms may be killed through impingement 

or entrainment. When fish and other aquatic life become trapped against the screen at the entrance 

to the cooling water intake structure through the force of the water being drawn through the intake 

structure, it is termed impingement. When eggs and larvae are sucked into the heat exchanger and 

eventually discharged from the facility, it is termed entrainment (Chapter 4.7; Federal Register, 

2006a).

The Clean Water Act, Section 316 (b) Phase III, established categorical regulations for 

offshore oil and gas cooling water intake structures. The NPDES permit began incorporating these 

regulations in NPDES General Permit GMG290000 for the USEPA Region 6 in 2007 and General 

Permit GEG460000 for the USEPA Region 4 in 2010 for new facilities that began construction after 

July 17, 2006, and that take in more than 2 million gallons per day of seawater, of which more than 

25 percent is used for cooling (USEPA, 2010 and 2012). The requirements have several tracks 

depending on whether the facility is a fixed or nonfixed facility and whether it has a sea chest intake 

or not. Some of the requirements include cooling water intake structure design requirements to 

meet a velocity of <0.5 ft (0.2 m) per second, construction to minimize impingement and/or 

entrainment, entrainment monitoring, recordkeeping, and completion of a source water biological 

study. Alteration to a sea chest intake structure on a mobile facility could render the facility less 

seaworthy, so it is not required. The requirements include a baseline study that characterizes the 

biological community in the vicinity of the structure or monitoring. A Joint Industry Biological 

Baseline Study was completed for USEPA Region 6 in June 2009 (LGL Ecological Research 

Associates, Inc., 2009), and an industry-wide cooling water intake structure entrainment monitoring 

study, approved by USEPA Region 6, was completed in 2014 (CSA and LGL Ecological Research 

Associates, Inc., 2014). For more information on the specifics regarding potential impacts to 

fisheries, refer to Chapter 4.7. 

3.1.5.1.6 Deck Drainage

Deck drainage includes all wastewater resulting from platform washings, deck washings, 

rainwater, and runoff from curbs, gutters, and drains, including drip pans and work areas. The 

USEPA’s general guidelines for deck drainage require that no free oil be discharged, as determined 

by visual sheen.
Impact-Producing Factors and Scenario 3-67

The quantities of deck drainage vary greatly depending on the size and location of the 

facility. An analysis of 950 GOM platforms during 1982-1983 determined that deck drainage 

averaged 50 bbl/day/platform (USEPA, 1993a). The deck drainage is collected, the oil is separated, 

and the water is discharged to the sea.

3.1.5.1.7 Treated Domestic and Sanitary Wastes

Domestic wastes originate from sinks, showers, laundries, and galleys. Sanitary wastes 

originate from toilets. For domestic waste, no solids or foam may be discharged. In addition, the 

discharge of all food waste within 12 nmi (14 mi; 22 km) from the nearest land is prohibited. In 

sanitary waste, floating solids are prohibited. Facilities with 10 or more people must meet the 

requirement of total residual chlorine greater than 1 mg/L and maintained as close to this 

concentration as possible. There is an exception in both general permits for the use of marine 

sanitation devices.

In general, a typical manned platform would discharge 35 gallons/person/day of treated 

sanitary wastes and 50-100 gallons/person/day of domestic wastes (USEPA, 1993a). It is assumed 

that these discharges are rapidly diluted and dispersed.

3.1.5.1.8 Minor/Miscellaneous Discharges

Minor and miscellaneous discharges include all other discharges not already discussed that 

may result during oil and gas operations. Minor or miscellaneous wastes may include desalination 

unit discharge, blowout preventer fluid, boiler blowdown, excess cement slurry, uncontaminated 

freshwater and saltwater, and miscellaneous discharges at the seafloor, such as subsea wellhead 

preservation and production control fluid, umbilical steel tube storage fluid, leak tracer fluid, and riser 

tensioner fluids. These discharges are regulated by the USEPA Region 4 and Region 6 NPDES 

permits. In all cases, no free oil shall be discharged with the waste. Unmanned facilities may 

discharge uncontaminated water through an automatic purge system without monitoring for free oil. 

The discharge of freshwater or seawater that has been treated with chemicals is permitted providing 

that the prescribed discharge criteria are met.

3.1.5.2 Operational Wastes and Discharges Generated by Service Vessels

Service vessels are discussed in Chapter 3.1.4.4. Discharges from supply/service vessels 

equal to or greater than 79 ft (24 m) in length are regulated by the U.S. Environmental Protection 

Agency’s NPDES under the Vessel General Permit (VGP). The Final 2013 VGP was issued on 

March 28, 2013, became effective on December 19, 2013, and expires on December 19, 2018 

(USEPA, 2013a). The Final 2013 VGP regulates 26 specific discharge categories, including numeric 

ballast-water discharge limits for most vessels, and ensures that ballast-water treatment systems are 

functioning correctly.

Discharges incidental to the normal operation of nonmilitary, nonrecreational vessels less 

than 79 ft (24 m) (i.e., "small vessels"), operating in a capacity as a means of transportation, are 
3-68 Gulf of Mexico Multisale EIS

regulated under the Small Vessel General Permit (sVGP). The Final 2014 sVGP was issued on 

September 10, 2014, became effective on December 19, 2014, and will expire on December 18, 

2019 (USEPA, 2014a). The USEPA issued the sVGP in anticipation of the December 18, 2014, 

expiration date of the then-existing moratorium on permitting small vessels, which specified that 

neither the USEPA nor the States may require NPDES permits, other than for ballast water, for 

incidental discharges from these small vessels. However, on December 18, 2014, President Obama 

signed into law the Howard Coble Coast Guard and Maritime Transportation Act of 2014, which 

extended that moratorium until December 18, 2017. Ballast-water discharges from small vessels still 

require NPDES permit coverage under the sVGP.

Operational wastes generated from supply/service vessels that support OCS oil- and gasrelated operations include bilge and ballast waters (Chapter 3.1.5.1.5), trash and debris (Chapter 

3.1.5.3.4), and sanitary and domestic wastes (Chapter 3.1.5.1.8). 

Bilge water is water that collects in the lower part of a ship. The bilge water is often 

contaminated by oil that leaks from the machinery within the vessel. The discharge of any oil or oily 

mixtures is prohibited under 33 CFR § 151.10; however, discharges may occur in waters greater 

than 12 nmi (14 mi; 22 km) from land if the oil concentration is less than 100 ppm. Discharges may 

occur less than 12 nmi (14 mi; 22.5 km) of land if the concentration is less than 15 ppm.

Ballast water is used to maintain stability of the vessel and may be pumped from coastal or 

marine waters. Generally, the ballast water is pumped into and out of separate compartments and is 

not usually contaminated with oil; however, the same discharge criteria apply as for bilge water 

(33 CFR § 151.10). Ballast water discharged from ships is one of the pathways for the introduction 

and spread of aquatic nuisance species. To address this issue, the USCG’s ballast-water discharge 

standard final rule, which was published on March 23, 2012 (Federal Register, 2012) and became

effective on June 21, 2012, established a standard for the allowable concentration of living 

organisms in ballast water discharged from ships in U.S. waters.

The discharge of trash and debris is prohibited (33 CFR §§ 151.51-77) unless it is passed 

through a comminutor and can pass through a 25-millimeter (mm) (1-in) mesh screen. All other 

trash and debris must be returned to shore for proper disposal with municipal and solid waste.

All vessels with toilet facilities must have a marine sanitation device that complies with 

40 CFR part 140 and 33 CFR part 159. Vessels complying with 33 CFR part 159 are not subject to 

State and local marine sanitation device requirements. However, a State may prohibit the discharge 

of all sewage within any or all of its waters. Domestic waste consists of all types of wastes 

generated in the living spaces on board a ship, including gray water that is generated from 

dishwasher, shower, laundry, bath, and washbasin drains. Gray water from vessels is not regulated 

under the NPDES in the Gulf of Mexico. Gray water should not be processed through the marine 

sanitation device, which is specifically designed to handle sewage.
Impact-Producing Factors and Scenario 3-69

3.1.5.3 Onshore Disposal of Waste and Discharge Generated Offshore or Onshore

3.1.5.3.1 Onshore Disposal of Wastes Generated from OCS Oil- and Gas-Related Facilities

Most wastes, other than produced water and water-based drilling muds and cuttings, are 

regulated by the USEPA and must be transported to shore or reinjected downhole. Additionally, 

wastes may be disposed of onshore because they do not meet permit requirements or because 

onshore disposal is economically advantageous. Wastes that are typically transported to shore 

include produced sand, aqueous fluids such as wash water from drilling and production operations, 

naturally occurring radioactive materials such as tank bottoms and pipe scale, industrial wastes, 

municipal wastes, and other exploration and production wastes (Dismukes, 2010). Most OBF muds 

and some SBF muds are recycled. If the physical and chemical properties of muds degrade, they 

may be disposed of or treated and reused for purposes other than drilling, instead of being recycled. 

Different reuses of treated muds include, among others, fill material, daily cover material at landfills, 

aggregate or filler in concrete, and brick or block manufacturing. The OBF cuttings are disposed of 

onshore or are injected onsite (USEPA, 1999). Both USEPA Regions 4 and 6 permit the discharge 

of SBF-wetted cuttings, provided the cuttings meet the criteria with regard to percent SBF retained, 

PAH content, biodegradability, and sediment toxicity. The SBF is either recycled or transferred to 

shore for regeneration and reuse or disposal. For information on OBF or SBF, refer to Chapter 

3.1.5.1.1. Drill cuttings contaminated with hydrocarbons from the reservoir fluid must be disposed of 

onshore or reinjected.

The USEPA allows treatment, workover, and completion fluids to be commingled with the 

produced-water stream if the combined produced-water/ treatment, workover, and completion 

discharges pass the toxicity test requirements of the NPDES permit. Facilities with less than 

10 producing wells may not have enough produced water to be able to effectively commingle the 

treatment, workover, and completion fluids with the produced-water stream to meet NPDES 

requirements (USEPA, 1993b). Spent treatment, workover, and completion fluid is stored in tanks 

on tending workboats or is stored on platforms and later transported to shore on supply boats or 

workboats. Once onshore, the treatment, workover, and completion wastes are transferred to 

commercial waste-treatment facilities and disposed of in commercial disposal wells. Offshore wells 

are projected to generate an average volume of 200 bbl from either a well treatment or workover job 

every 4 years. Each new well completion would generate about 150 bbl of completion fluid.

Operators are prohibited in the GOM from discharging any produced sands offshore. Cutting 

boxes (15- to 25-bbl capacities), 55-gallon steel drums, and cone-bottom portable tanks are used to 

transport the solids to shore via offshore service vessels. Total produced sand from a typical 

platform is estimated to be 0-35 bbl/day (USEPA, 1993b). Refer to Chapter 3.1.5.1.4 for more 

information on produced sands. Both Texas and Louisiana have State oversight of exploration and 

production waste-management facilities (Veil, 1999).
3-70 Gulf of Mexico Multisale EIS

3.1.5.3.2 Onshore Disposal and Storage Facilities Supporting OCS-Generated Operational 

Wastes

BOEM-funded research by Dismukes et al. (2007) further supports past conclusions that 

existing solid-waste disposal infrastructure is adequate to support both existing and projected 

offshore oil and gas drilling and production needs. Recently, there is a trend toward incorporating 

more innovative methods for waste handling in an attempt to reduce the chance of adverse 

environmental impacts. Some of these innovative methods include hydrocarbon recovery/recycling 

programs, slurry fracture injection, treating wastes for reuse as road base or levee fill, and 

segregating waste streams to reduce treatment time and improve oil recovery (Dismukes, 2011b). 

Research shows that the volume of OCS-generated waste is closely correlated with the level of 

offshore drilling and production activity. For each alternative (A, B, C, or D), existing onshore 

facilities would continue to be used to dispose of wastes generated offshore. However, no new 

disposal facilities are expected to be licensed as a direct result of Alternative A, B, C, or D. There is 

no current expectation for new onshore waste disposal facilities to be authorized and constructed 

during the 2017-2066 period as a direct result of each alternative (A, B, C, or D). If needed, existing 

facilities may undergo expansion, but no new disposal facilities are expected.

3.1.5.3.3 Discharges from Onshore Support Facilities

The primary onshore facilities that support offshore oil- and gas-related activities include 

service bases, helicopter hubs at local ports/service bases, construction facilities (i.e., platform 

fabrication yards, pipeyards, and shipyards), processing facilities (i.e., refineries, gas processing 

plants, and petrochemical plants), and terminals (i.e., pipeline shore facilities, barge terminals, and 

tanker port areas). Water discharges from these facilities are from either point sources, such as a 

pipe outfall, or nonpoint sources, such as rainfall run-off from paved surfaces. The USEPA or the 

USEPA-authorized State program regulates point-source discharges as part of the NPDES. 

Facilities are issued general or individual permits that limit discharges specific to the facility type and 

the waterbody receiving the discharge. Other wastes generated at these facilities are handled by 

local municipal and solid-waste facilities, which are also regulated by the USEPA or an USEPAauthorized State program. 

3.1.5.3.4 Beach Trash and Debris

The discharge of marine debris by the offshore oil and gas industry and supporting activities 

is subject to a number of laws and treaties. These include the Marine Debris Research, Prevention, 

and Reduction Act; the Marine Plastic Pollution Research and Control Act; and the MARPOL-Annex 

V treaty. Regulation and enforcement of these laws is conducted by a number of agencies such as 

the U.S. Environmental Protection Agency, NOAA, and USCG. The BSEE policy regarding marine 

debris prevention is outlined in NTL 2015-BSEE-G03, “Marine Trash and Debris Awareness and 

Elimination.” This NTL instructs OCS operators to post informational placards that outline the legal 

consequences and potential ecological harms of discharging marine debris. This NTL also states 

that OCS workers should complete annual marine debris prevention training; operators are also 

instructed to develop a certification process for the completion of this training by their workers. 
Impact-Producing Factors and Scenario 3-71

These various laws, regulations, and NTL would likely minimize the discharge of marine debris from 

OCS operations.

3.1.6 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. Regulations and processes related to structure and site clearance are 

discussed in Appendix A.13. The structures are generally grouped into two main categories 

depending upon their relationship to the platform/facilities (i.e., piles, jackets, caissons, templates, 

mooring devises, etc.) or the well (i.e., wellheads, casings, casing stubs, etc.).

A varied assortment of severing devices and methodologies has been designed to cut 

structural targets during the course of decommissioning activities. These devices are generally 

grouped and classified as either nonexplosive or explosive, and they can be deployed and operated 

by divers, ROVs, or from the surface. Which severing tool the operators and contractors use takes 

into consideration the target size and type, water depth, economics, environmental concerns, tool 

availability, and weather conditions.

Nonexplosive severing tools are used on the OCS for a wide array of structure and well 

decommissioning targets in all water depths. Based on 10 years of historical data (1994-2003), 

nonexplosive severing is employed exclusively on about 58 (~37%) removals per year (USDOI, 

MMS, 2005). Since many decommissionings use both explosive and nonexplosive technologies 

(prearranged or as a backup method), the number of instances may be much greater. Common 

nonexplosive severing tools consist of abrasive cutters (e.g., sand cutters and abrasive water jets), 

mechanical (carbide) cutters, diver cutting (e.g., underwater arc cutters and the oxyacetylene/oxyhydrogen torches), and diamond wire cutters.

With the exception of minor air and water quality concerns (i.e., exhaust from support 

equipment and toxicity of abrasive materials), nonexplosive severing tools generally cause little to no 

environmental impacts; therefore, there are very few regulations regarding their use. However, the 

use of nonexplosive cutters leads to greater human health and safety concerns, primarily because 

(1) divers are often required in the methodology (e.g., torch/underwater arc cutting and external tool 

installation and monitoring), (2) more personnel are required to operate them (increasing their risks 

of injury in the offshore environment), (3) lower success rates require that additional cutting attempts 

be made, and (4) the cutters can only sever one target at a time, taking on average 30 minutes to 

several hours for a complete cut (USDOI, MMS, 2005). The last two items are often hard to quantify 

and to assign risks to the cutters, but the main principle is that there is a linear relationship between 

the length of time any offshore operation is staged and on-site (exposure time) and the potential for 

an accident to occur (Twachtman, Snyder, & Byrd, Inc. and Louisiana State University, Center for 

Energy Studies, 2004). Therefore, even if there are no direct injuries or incidents involving a diver or 

severing technicians, the increased “exposure time” needed to successfully sever all necessary 

targets could result in unrelated accidents involving other barge/vessel personnel.
3-72 Gulf of Mexico Multisale EIS

Explosive severance tools can be deployed on almost all structural and well targets in all 

water depths. Historically, explosive charges are used in about 98 (~63%) decommissioning 

operations annually (USDOI, MMS, 2005), often as a back-up cutter when other methodologies 

prove unsuccessful. Explosives work to sever their targets by using (1) mechanical distortion 

(ripping), (2) high-velocity jet cutting, and (3) fracturing or “spalling.”

Mechanical distortion is best exhibited with the use of explosives such as standard and 

configured bulk charges. If the situation calls for minimal distortion and an extremely clean severing, 

then most contractors rely upon the jet-cutting capabilities of shaped charges. In order to “cut” with 

these explosives, the specialized charges are designed to use the high-velocity forces released at 

detonation to transform a metal liner (often copper) into a thin jet that slices through its target. The 

least used method of severing currently in use on the Gulf of Mexico OCS is fracturing, which uses a 

specialized charge to focus pressure waves into the target wall and use refraction forces to spall or 

fracture the steel on the opposing side (NRC, 1996).

In water depths >800 m (2,625 ft), OCS regulations offer the lessees the option to avoid the 

jetting by requesting alternate removal depths for well abandonments (30 CFR § 250.1716(b)(3)) 

and facilities (30 CFR § 250.1728(b)(3)). Above mudline cuts would be allowed for depths >800 m 

(2,625 ft), with reporting requirements on the remnant’s description and height off of the seafloor to 

BOEM; this is data necessary for subsequent reporting to the U.S. Navy. With the exception of 

several dynamically positioned vessels, deepwater drilling operations most often use moored 

semisubmersibles. Coupled with the growing number of TLPs, spars, and MODUs, operators and 

contractors have to contend with new demands for quick-disconnect and line severing tools that may 

be necessary during emergencies and decommissioning operations when the anchor cannot be 

retrieved. 

Some of the mooring systems used in deepwater operations have quick-disconnect 

technology built into their designs. Using several varieties of exploding bolts, electromechanical 

couplings, and/or hydraulic-actuated connections, these release mechanisms can be controlled from 

the vessel and triggered on short notice. In situations where the mooring system disconnects were 

not employed or become disabled, severing contractors have several mechanical and explosive 

cutting tools at their disposal for shearing cables, lines, and chains from their moorings. Mechanical 

cutters such as wheel and guillotine saws, hydraulic shears, and diamond wire cutters can be 

deployed using ROVs, allowing the cuts to be performed as close to the anchors as possible. In 

much the same way, small explosive shaped-charge devices can be positioned onto the mooring 

targets by ROVs. These external cutters are generally designed with hydraulic/electric actuators 

and hinge systems that allow the shaped charge to be “clamped” over the target and then detonated 

after the ROV is removed to a safe distance. Together, these effective severing methods and the 

deep-diving capabilities of the ROVs allow for full recovery of the lines/cables/chains, which could 

present a future hazard to commercial fishing gear and navigation.

After bottom-founded objects are severed and the structures are removed, operators are 

required to use trawling or sonar searches to verify that the site is clear of any obstructions that may 
Impact-Producing Factors and Scenario 3-73

The Bureau of Ocean Energy Management, 

Regulation and Enforcement issued NTL 

2010-G05 to establish guidelines for 

decommissioning structures within the 

timeframes established by regulations, 

conditions of approval, and lease instruments. 

conflict with other uses. Refer to Appendix A.13 for a more detailed discussion of site-clearance 

processes.

Alternative A*: Table 3-2 shows platform removals by water-depth subarea as a result of 

Alternative A. Of the 16-280 production structures estimated to be removed as a result of a 

proposed action under Alternative A, 9-193 production structures (installed landward of the 800-m 

[2,625-ft] isobath) could likely be removed using explosives. It is anticipated that multiple 

appurtenances would not be removed from the seafloor if placed in waters exceeding 800 m 

(2,625 ft). An estimate of the well stubs and other various subsea structures that may be removed 

using explosives is not possible at this time. For the purposes of impact assessment, the prudent 

assumption should be that charges used for well severance behave in the same manner and 

produce parameters of the same magnitude as do charges detonated on the bottom in open 

water.

Alternative B*: Table 3-2 shows platform removals by water-depth subarea as a result of 

Alternative B. Of the 14-247 production structures estimated to be removed as a result of 

Alternative B, 7-172 production structures (installed landward of the 800-m [2,625-ft] isobath) 

could likely be removed using explosives. It is anticipated that multiple appurtenances would not 

be removed from the seafloor if placed in waters exceeding 800 m (2,625 ft).

Alternative C*: Table 3-2 shows platform removals by water-depth subarea as a result of 

Alternative C. Of the 9-33 production structures estimated to be removed as a result of 

Alternative C, 4-21 production structures (installed landward of the 800-m [2,625-ft] isobath) could 

likely be removed using explosives. It is anticipated that multiple appurtenances would not be 

removed from the seafloor if placed in waters exceeding 800 m (2,625 ft).

*Alternative D could reduce activity values of the combined Alternative A, B, or C by up to 

4 percent. Refer to Chapter 2.2.2.4 for more information.

3.1.6.1 Structure Age and Idle Iron

Federal regulations require that offshore 

leases be cleared of all structures within 1 year 

after production on the lease ceases, but a 

producing lease can hold infrastructure idle for 

as long as the lease is producing (30 CFR § 

250.112). Refer to Chapter 3.1.6 and 

Appendix A.13 for more information on 

decommissioning. As of 2015, the average age 

of all removed offshore structures was 19 years. Simpler structures like caissons had an average 

lifespan of 17 years when decommissioned, and more complex structures like fixed platforms had an 

average lifespan of 20 years. The average age of all active platforms is 29 years. Although 

accidents, storm damage, and unforeseen geological problems may cause platforms to be removed 
3-74 Gulf of Mexico Multisale EIS

early, the discrepancy between the assumed and actual life of platforms is probably explained by the 

end of economic production from the field rather than by design or engineering factors unique to 

each platform. Any infrastructure that is decommissioned and no longer “economically viable,” 

severely damaged, or idle on active leases is considered “idle iron” according to NTL 2010-G05, 

“Decommissioning Guidance for Wells and Platforms.” 

The BSEE’s idle iron policy keeps inactive facilities and structures from littering the Gulf of 

Mexico by requiring companies to dismantle and responsibly dispose of infrastructure after they plug 

nonproducing wells. BSEE enforces these lease agreements primarily for two reasons beyond the 

CFR requirement:

• Environmental Effects – Toppled structures pose a potential environmental 

hazard due to the topsides and the associated equipment, electronics, wiring, 

piping, tanks, etc., that are left on the bottom of the Gulf of Mexico. These items 

pose a financial, safety, and environmental burden, and must be removed from 

the bottom.

• Safety – Severe weather such as hurricanes have toppled, severely damaged, or 

destroyed the structures associated with oil and gas production. While any 

structure could be destroyed during a hurricane, idle facilities pose an 

unnecessary risk of leaks from wells into the environment and potential damage 

to the ecosystem, passing ships, and commercial fishermen.

The typical life span of a pipeline has been estimated to be 20-40 years, but with current 

corrosion management, that lifetime has been substantially increased. One technique for extending 

the life of a gas pipeline is to coat the inside of the pipe periodically with a corrosion-inhibiting 

substance. The coating may be applied as either an aerosol pumped in with the production stream 

or as a liquid “slug” pushed through the pipe with a pig. The slug treatment provides greater 

protection (Cranswick, 2001). Corrosion can lead to major accidents on platforms. In 2011, a 

platform owned by Mariner Energy, about 100 mi (161 km) off the Louisiana shore, was using a 

piece of steel heating equipment that had corroded over its 30-year life, causing it to leak 

hydrocarbons that ignited the platform (Sebastian, 2011).

Subsea wells, in which the wellhead, Christmas tree, and production-control equipment are 

all located on the seafloor, were introduced in the 1970’s and started to grow especially popular in 

the 1980’s and 1990’s. Older generations of subsea wells had a designed life of 15-20 years, and 

many of those devices are reaching the end of that time span (Holeywell, 2014).

3.1.6.2 Rigs-to-Reefs Policy

Although BSEE supports and encourages the reuse of obsolete oil and gas structures as 

artificial reefs and is a cooperating agency in implementing the National Artificial Reef Plan, specific 

requirements must be met for a departure to be granted. More information on these regulations and 

processes can be found in Appendix A.15. Structure-removal permit applications requesting a 
Impact-Producing Factors and Scenario 3-75

departure under the Rigs-to-Reefs Policy undergo technical and environmental reviews. The policy 

document details the minimum engineering and environmental standards that operators/lessees 

must meet to be granted approval to deploy a structure as an artificial reef. Conditions of approval 

are applied as necessary to minimize the potential for adverse effects to sensitive habitat and 

communities in the vicinity of the structure and proposed artificial reef site. Additionally, structures 

deployed as artificial reefs must not threaten nearby structures or prevent access to oil and gas, 

marine mineral, or renewable energy resources.

Routine activities include the decommissioning of structures, but redeployment and reefing is 

considered a State activity. Refer to Chapter 3.3.2.1.2 for more information on artificial reefs.

3.1.7 Coastal Infrastructure

The following chapters discuss coastal impact-producing factors and provide scenario 

projections for onshore coastal infrastructure that may potentially result from a proposed lease sale 

under Alternative A, B, or C in the 2017-2022 Five-Year Program. Under Alternative D, the number 

of blocks that would become unavailable for lease represents only a small percentage (<4%) of the 

total number of blocks to be offered under Alternative A, B, or C. Therefore, Alternative D could 

reduce offshore infrastructure and activities by up to 4 percent when chosen in conjunction with 

Alternative A, B, or C. However, it is also possible that Alternative D would only shift the location of 

offshore infrastructure and activities farther from sensitive topographic zones and not lead to a 

reduction in offshore infrastructure and activities. Refer to Chapter 2.2.2.4 for more information on 

Alternative D. This discussion describes the potential need for new facility construction and for 

expansions at existing facilities. A detailed description of the baseline affected environment for land 

use and coastal infrastructure in the GOM can be found in Chapter 4.14.1.1. 

Oil and gas exploration, production, and development activities on the OCS are supported by 

an expansive onshore infrastructure industry that includes large and small companies providing an 

array of services from construction facilities, service bases, and waste disposal facilities to crew, 

supply, and product transportation, as well as processing facilities. It is an extensive and mature 

system providing support for both offshore and onshore oil and gas activities in the GOM region 

(Figure 3-10). The extensive presence of this coastal infrastructure is not subject to rapid 

fluctuations and results from long-term industry trends. Existing oil and gas infrastructure is 

expected to be sufficient to handle development associated with a proposed action. Should there be 

some expansion at current facilities, the land in the analysis area is sufficient to handle such 

development.
3-76 Gulf of Mexico Multisale EIS

Figure 3-10. Onshore Infrastructure. 
Impact-Producing Factors and Scenario 3-77

Impact-producing factors associated with coastal infrastructure include service bases, gas 

processing plants, pipeline landfalls, navigation channels, and waste disposal facilities. Chapter 

3.1.5.3 addresses onshore waste disposal. Chapter 3.1.4.1 discusses pipeline landfalls. While no 

single proposed lease sale under Alternative A, B, or C is projected to substantially change existing 

OCS-related service bases or require any additional service bases, it would contribute to the use of 

existing service bases. Sufficient land exists to construct a new gas processing plant in the unlikely 

event that one should be needed. However, because the current spare capacity at existing facilities 

should be sufficient to satisfy new gas production, the need to construct a new facility would possibly 

materialize only toward the end of the life of a proposed action. Therefore, BOEM projects 0-1 new 

gas processing plants to result from a proposed lease sale under Alternative A, B, or C. While a 

proposed action would contribute to the continued need for maintenance dredging of existing 

navigation channels, a mature network of navigation channels already exists in the analysis area; 

therefore, no new navigation channel construction would be expected as a direct result of a 

proposed lease sale under Alternative A, B, or C (Dismukes, official communication, 2015).

BOEM continuously collects new data and monitors changes in infrastructure demands in 

order to support scenario projections that reflect current and future industry conditions. The scenario 

projections outlined below reflect the already well-established industrial infrastructure network in the 

GOM region and fluctuations in OCS oil- and gas-related activity levels. To prevent underestimating 

potential effects, BOEM makes conservative infrastructure scenario estimates; therefore, a 

projection of between 0 and 1 is more likely to be 0 than 1.

The following chapters provide the current trends, or outlook scenario projections, for the 

varied infrastructure categories. The primary sources for all of the information on coastal 

infrastructure and activities presented here are BOEM’s Gulf of Mexico OCS Region’s fact books: 

(1) OCS-Related Infrastructure in the Gulf of Mexico Fact Book (The Louis Berger Group, Inc., 

2004); (2) Fact Book: Offshore Oil and Gas Industry Support Sectors (Dismukes, 2010); and 

(3) OCS-Related Infrastructure Fact Book; Volume I: Post-Hurricane Impact Assessment and 

Volume II: Communities in the Gulf of Mexico (Dismukes, 2011b).

3.1.7.1 Construction Facilities

3.1.7.1.1 Platform Fabrication Yards

Facilities where platforms (and drilling rigs) are fabricated are called platform fabrication 

yards. Most platforms are fabricated onshore and then towed to an offshore location for installation. 

When an oil and/or gas discovery occurs, an exploratory drilling rig would be either replaced with, or 

converted to, a production platform assembled at the site using a barge equipped with heavy lift 

cranes. Platform fabrication is highly dependent on the structural nature of the oil and gas industry. 

As oil prices fluctuate, platform fabrication yards adjust accordingly. When oil prices are low, they 

diversify their operations into other marine-related activities or scale back on the overall scope of 

their operations. The variety of diversification strategies may include drilling rig maintenance and 

re-builds, barge or vessel fabrication, dry-docking, or equipment survey.
3-78 Gulf of Mexico Multisale EIS

The existing fabrication yards do not operate as “stand alone” businesses; rather, they rely 

heavily on a dense network of suppliers of products and services. Also, since such a network has 

been historically evolving in the GOM region for many decades, existing fabrication yards possess a 

compelling force of economic concentration to prevent the emergence of new fabrication yards. 

There are 54 platform fabrication yards in the analysis area, with the highest concentration in 

Louisiana at 37 and followed by Texas at 12 (Table 3-4). Given the large size of offshore platforms, 

fabrication yards necessarily span several hundred acres. The location of platform fabrication yards 

is tied to the availability of a navigable channel sufficiently large enough to allow the towing of bulky 

and long structures, such as offshore drilling and production platforms. Thus, platform fabrication 

yards are located either directly along the Gulf Coast or inland along large navigable channels, such 

as the Intracoastal Waterway.

Alternative A, B, C, or D: No new facilities are expected to be constructed as a result of 

Alternative A, B, C, or D. The potential exists for some current yards to close, be bought out, or 

merge over the 50-year analysis period (2017-2066), resulting in fewer active yards in the analysis 

area.

3.1.7.1.2 Shipbuilding and Shipyards

There are several kinds of shipyards throughout the Gulf Coast region that build and repair 

all manner of vessels, many of which are not related to OCS oil- and gas-related activities. These 

marine vessels are perhaps the most important means of transporting equipment and personnel 

from onshore bases and ports to offshore drilling and production structures. The shipbuilding and 

repair industry has struggled over the last few decades. Since the mid-1990’s, there has been some 

industry stabilization, but the outlook for shipbuilding and shipyards is uncertain. The industry is 

overly dependent on military contracts and faces numerous economic challenges, such as the lack 

of international competitiveness, workforce development challenges, availability of capital, and the 

lack of research and development funding. In the GOM region, there is a direct correlation between 

OCS oil- and gas-related activities and the demand or opportunities for expanding shipbuilding and 

offshore support vessels. There are 137 shipyards located within the analysis areas (Table 3-4). To 

a great extent, growth would be based on a successful resolution of several pertinent issues that 

have affected and continue to affect shipbuilding in the U.S. and particularly in the analysis area: 

maritime policy; declining military budget; foreign subsidies; USCG regulations; Oil Pollution Act of 

1990; financing; and an aging fleet. Generally, as oil and gas drilling and production increase, the 

demand for an expanded shipbuilding effort also increases. However, despite the drop in oil and 

gas prices at the end of 2014 and beginning of 2015, Louisiana-based Bollinger Shipyards began 

construction on four massive dry docks able to service 300-ft (91-m) or larger vessels (Jervis, 2015).

Alternative A, B, C, or D: No new facilities are expected to be constructed as a result of 

Alternative A, B, C, or D. There is more than an adequate supply of shipyard resources in the 

GOM region. Some shipyards may close, be bought out, or merge over the 50-year analysis 

period (2017-2066), resulting in fewer active yards in the analysis area.
Impact-Producing Factors and Scenario 3-79

3.1.7.1.3 Pipe-Coating Facilities and Yards

Pipe-coating plants generally receive manufactured pipe by rail or water at either their plant 

or pipeyard depending on their inventory capabilities. At the plant, pipes that transport oil and gas 

are coated on the interior and exterior to protect from corrosion and abrasion. There are 19 pipecoating plants in the analysis areas (Table 3-4). Pipe-coating facilities receive manufactured pipe, 

which they then coat the surfaces of with metallic, inorganic, and organic materials to protect from 

corrosion and abrasion and to add weight to counteract the water’s buoyancy. Two to four sections 

of pipe are then welded at the plant into 40-ft (12-m) segments. The coated pipe is stored (stacked) 

at the pipe yard until it is needed offshore.

To meet deepwater demand, pipe-coating companies were expanding capacity or building 

new plants before the Deepwater Horizon explosion, oil spill, and response; afterwards, activity 

levels dropped temporarily, then rebounded until the oil price drop and economic downturn of late 

2014/early 2015, resulting in a decrease in OCS activity levels and less demand for pipe-coating 

services. As activity levels fluctuate in the GOM, the demands for pipe-coating services fluctuate 

accordingly.

Alternative A, B, C, or D: No new facilities are expected to be constructed as a result of 

Alternative A, B, C, or D. Current capacity, supplemented by expansions at already existing 

facilities, is anticipated to meet OCS Program demand.

3.1.7.2 Support Facilities and Transportation

3.1.7.2.1 Service Bases and Ports

A service base is a community of businesses that load, store, and supply equipment, 

supplies, and personnel needed at offshore work sites. A service base may also be referred to as a 

supply base or terminal and may be associated with a port. A proposed lease sale under Alternative 

A, B, or C is expected to utilize only those ports that currently have facilities used by the oil and gas 

industry as offshore service bases. Although a service base may primarily serve the adjacent OCS 

planning area and Economic Impact Areas (EIAs) in which it is located, it may also provide 

substantial services for the other OCS planning areas and EIAs. Table 3-10 shows the 50 services 

bases organized by EIA, and Figure 3-8 shows the geographic location of the service bases.
3-80 Gulf of Mexico Multisale EIS

Table 3-10. OCS Oil- and Gas-Related Service Bases.

State EIA County/Parish

Texas

TX-1 Port Isabel (Cameron) Port Mansfield (Willacy)

TX-2 

Aransas Pass (Nueces)

Bayside (Aransas)

Corpus Christi (Nueces)

Harbor Island (Nueces)

Ingleside (San Patricio)

Port Aransas (Nueces)

Port O’Connor (Calhoun)

Rockport (Aransas)

TX-3 Freeport (Brazoria)

Galveston (Galveston)

Pelican Island (Galveston) Surfside (Harris)

TX-5 Port Arthur (Jefferson)

Sabine Pass (Jefferson)

Louisiana

LA-1 Cameron (Cameron) Grand Chenier (Cameron) Lake Charles (Calcasieu)

LA-3 Amelia (St. Mary)

Bayou Boeuf (St Mary)

Berwick (St. Mary) Cocodrie (Terrebonne)

LA-4 

Amelia (St. Mary)

Bayou Boeuf (St. Mary)

Berwick (St. Mary)

Cocodrie (Terrebonne)

Dulac (Terrebonne)

Fourchon (Lafourche)

Gibson (Terrebonne)

Houma (Terrebonne)

Leeville (Lafourche)

Louisa (St. Mary)

Morgan City (St. Mary)

New Iberia (Iberia)

Patterson (St. Mary)

Theriot (Terrebonne)

Weeks Island (Iberia)

LA-6 Empire (Plaquemines)

Grand Isle (Jefferson)

Harvey (Jefferson)

Hopedale (St. Bernard)

Paradis (St. Charles)

Venice (Plaquemines)

Mississippi MS-1 Pascagoula (Jackson)

Alabama AL-1 Bayou LaBatre (Mobile) Mobile (Mobile) Theodore (Mobile)

Florida FL-1 Panama City (Bay)

EIA = Economic Impact Area.

As the industry continues to evolve, so do the requirements of the onshore support network. 

With advancements in technology, the shore-side supply network would continue to be challenged to 

meet the needs and requirements. The intermodal nature of oil and gas operations gives ports 

(which traditionally have water, rail, and highway access) a natural advantage as ideal locations for 

onshore activities and intermodal transfers (Figure 3-11). Therefore, ports would continue to be a 

vital factor in the total process and must incorporate the needs of the offshore oil and gas industry 

into their planning and development efforts, particularly with regard to determining their future 

investment needs. In this manner, both technical and economic determinants influence the 

dynamics of port development.
Impact-Producing Factors and Scenario

3-81

Figure 3-11. OCS-Related Ports and Waterways in the Gulf of Mexico.
3-82 Gulf of Mexico Multisale EIS

Expansion of some existing service bases is expected to occur to capture and accommodate 

the current and future oil and gas business that is generated by development on the OCS. In early 

2015, for example, Louisiana-based Bollinger Shipyards was constructing four massive dry docks 

able to service 300-plus-foot (91-plus-meter) vessels at Port Fourchon while Schlumberger was 

expanding its Port Fourchon operations (Jervis, 2015). Some channels in and around the service 

bases would need to be deepened and expanded in support of deeper draft vessels and other port 

activities, some of which would be OCS related. Channel depths at most major U.S. ports typically 

range from 35 to 45 ft (11 to 14 m). The current generation of new large ships that service the 

offshore industry requires channels from 45 to 53 ft (14 to 16 m).

Alternative A, B, C, or D: Alternative A, B, C, or D would not change identified service 

bases or require any additional service bases. The OCS oil- and gas-related activities over the 

course of the 50-year analysis period (2017-2067) would continue to contribute to the ongoing 

trend of consolidating activities at specific ports, especially with respect to deepwater activities 

(i.e., Port Fourchon and Galveston).

3.1.7.2.2 Helicopter Hubs

There are 241 identified heliports within the GOM region that support OCS oil- and gasrelated activities; 118 are located in Texas, 115 in Louisiana, 0 in Florida, 4 in Mississippi, and 4 in 

Alabama (Table 3-4). Industry consolidation has resulted in a small number of large helicopter 

service providers. The Gulf of Mexico is served primarily by three large operators, which account for 

nearly 80 percent of the aircraft available in the GOM. This industry is largely dependent on the 

level of production, development, and exploration in the GOM. Demand for helicopters increases 

with an increase in activity levels associated with oil and gas exploration, development, and 

production; however, as oil and gas companies seek to reduce costs with respect to air 

transportation services, the demand for these services is reduced. Greater total (and relative) 

deepwater activities in the GOM are forcing major changes on the transportation industry in the 

region. Helicopters must have the capability of traversing longer distances with more cargoes than 

were necessary in the past. Also, new technologies may permit companies to reduce staffing levels 

on both old and new installations, which could translate into less demand for helicopter services.

Alternative A, B, C, or D: No new helicopter hubs are projected as a result of a proposed 

lease sale or the OCS Program; however, if activity levels increase, they may expand at current 

locations. Chapter 3.1.4.5 provides information on helicopter operation projections.

3.1.7.2.3 Tanker Port Areas

The transport of OCS-produced oil from FPSO operations to inside or shore-side facilities 

would be accomplished with shuttle tankers rather than oil pipelines. The following tanker ports 

were identified as destinations for shuttle tankers transporting crude oil from FPSO operations in the 

GOM: Houston or the Louisiana Offshore Oil Port are most likely candidates, followed by possibly 

Corpus Christi, Freeport, and Port Arthur/Beaumont, Texas, although it would be most likely for oil to 
Impact-Producing Factors and Scenario 3-83

be transported to Port Arthur/Beaumont via pipeline (Dismukes, official communication, 2011a). 

Tankers that offloaded oil from Petrobras’ Cascade Chinook delivered to the following areas: 

Nederland, Texas; Pascagoula, Mississippi; Mobile, Alabama; Port Arthur, Texas; Garyville, 

Louisiana; Houston, Texas; Lake Charles, Louisiana; Saint Rose, Louisiana; Galveston Bar, Texas; 

Texas City, Texas; Corpus Christi, Texas; Baton Rouge, Louisiana; the Louisiana Offshore Oil Port; 

and Yabucoa, Puerto Rico.

The number of shuttle-tanker trips to port in a given year is primarily a function of the FPSO 

production rate and the capacity of supporting shuttle tankers. Considering an FPSO operating at a 

peak production rate of 150,000 bbl/day, supported by shuttle tankers of 500,000-bbl capacity, 

offloading could occur once every 3.3 days. This would equate to 54.75 MMbbl of production with 

110 offloading events and shuttle-tanker transits to GOM coastal or offshore ports annually per 

FPSO.

Alternative A, B, C, or D: Chapter 3.1.4.3 provides BOEM’s current tankering projections. 

Tanker trips associated with Alternative A, B, C, or D would represent a small percentage of 

annual tanker trips into identified tanker ports. Therefore, no new tanker port facilities are 

projected to result from Alternative A, B, C, or D.

3.1.7.2.4 Barge Terminals

The OCS oil barged from offshore platforms to onshore barge terminals represents a small 

portion of the total amount of oil barged in coastal waters. While there is a tremendous amount of 

barging that occurs in the coastal State waters of the GOM, no estimates exist of the volume of this 

barging that is directly attributable to the OCS industry. Secondary barging of OCS oil often occurs 

between terminals or from terminals to refineries. Oil that is piped to shore facilities and terminals is 

often subsequently transported by barge up rivers, through the Gulf Intracoastal Waterway, or along 

the coast.

Alternative A, B, C, or D: Barging of OCS production is expected to remain stable. No 

major modifications or new barge terminals are expected to be constructed as a direct result of a 

proposed lease sale or OCS Program operations. Chapter 3.1.4.2 provides BOEM’s current 

barging projections.

3.1.7.2.5 Pipeline Shore Facilities

The term “pipeline shore facility” is a broad term describing the onshore location where the 

first stage of processing occurs for OCS pipelines carrying different combinations of oil, condensate, 

gas, and produced water. Some processing may occur offshore at the platform; only onshore 

facilities are addressed in this discussion. Pipelines carrying only dry gas do not require pipeline 

shore facilities; the dry gas is piped directly to the gas processing plant. Therefore, new pipeline 

shore facilities are projected to only result from oil pipeline landfalls. A pipeline shore facility may 

support one or several pipelines; therefore, new pipeline shore facilities are projected to only result 
3-84 Gulf of Mexico Multisale EIS

from larger pipelines (>12 in; 30 cm). Although older facilities may be located in wetlands, current 

permitting programs prohibit or discourage companies from constructing any new facilities in 

wetlands. Also, it is more cost effective for companies to tie into the existing offshore pipeline 

network.

Alternative A, B, C, or D: No new pipeline shore facilities are projected as a result of 

Alternative A, B, C, or D, which would represent a small percent of the resources handled by 

existing shore facilities. Chapter 3.1.4.1 provides BOEM’s current pipeline landfall projections.

3.1.7.2.6 Navigation Channels

Coastal oil- and gas-related infrastructure in the GOM region includes a vast and complex 

system of navigation channels that have been in existence for decades. While a proposed lease 

sale under Alternative A, B, or C would contribute to the continued need for maintenance dredging of 

existing navigation channels, a mature network of navigation channels already exists in the analysis 

area; therefore, no new navigation channel construction would be expected as a direct result of a 

proposed lease sale under Alternative A, B, or C. Refer to Chapter 3.1.4.6 for more information on 

navigation channels. 

Alternative A, B, C, or D: No new navigation channels are expected to be constructed as 

a result of Alternative A, B, C, or D. Chapter 3.1.4.6 provides BOEM’s current scenario analysis 

for navigation channels.

3.1.7.2.7 Waste Disposal Facilities

A variety of different types of wastes are generated by offshore oil and gas exploration and 

production activities along the GOM. Some wastes are common to any manufacturing or industrial 

operation (e.g., garbage, sanitary waste [toilets], and domestic waste [sinks and showers]) while 

others are unique to the oil and gas industry (e.g., drill fluids and produced water). Most waste must 

be transported to shore-based facilities for storage and disposal. In the analysis area, there are 

16 waste disposal facilities in Texas, 29 in Louisiana, 3 each in Mississippi and Alabama, and 2 in 

Florida. Refer to Chapter 3.1.5.3 for more information. 

Alternative A, B, C, or D: No new waste disposal facilities are expected to be constructed 

as a result of Alternative A, B, C, or D. Chapter 3.1.5.3 provides BOEM’s current scenario 

analysis for waste disposal facilities.

3.1.7.2.8 Natural Gas Storage Facilities

Most of the natural gas storage facilities in the GOM region are salt caverns. The 

overwhelming majority of all salt cavern storage facilities operating in the U.S. are located along the 

GOM. Gulf Coast salt caverns account for only 4.2 percent of total U.S. working gas capacity and 

15.5 percent of total U.S. deliverability. In the GOM, Texas has 14 salt cavern sites with 78 billion 
Impact-Producing Factors and Scenario 3-85

cubic feet per day (Bcf/day) of working gas capacity and Louisiana has 7 sites with 48 Bcf/day of 

working gas capacity, Mississippi has 3 sites with 32 Bcf/day of working gas capacity, and Alabama 

has 1 site with 7 Bcf/day of working gas capacity (USDOE, Energy Information Administration, 

2007). Not all of these facilities are located within the BOEM-defined EIAs. More specifically, there 

are 22 underground natural gas storage facilities in the BOEM-defined EIAs. These facilities total 

165 Bcf/day of working gas capacity.

Alternative A, B, C, or D: No new natural gas storage facilities are projected as a result of 

Alternative A, B, C, or D. Any expansions or new facilities would be the result of onshore rather 

than offshore production.

3.1.7.3 Processing Facilities

The following chapters discuss various processing facilities, i.e., gas processing facilities, 

refineries, and LNG facilities. These are included as the final endpoint for OCS oil and gas; 

however, at the time that OCS product reaches these facilities, it has already been joined with nonOCS product from State waters and onshore activities. The percentage of oil and gas product 

processed by these facilities that actually originated from OCS waters has not been determined and 

is not likely to ever be possible to discover since it is due to a number of factors unrelated to the 

delivery of OCS product, such as downstream demand. Therefore, in contrast to most other

infrastructure types, scenario projections for processing facilities are inherently limited with no direct 

correlation to OCS oil- and gas-related activities. 

Alternative A, B, C, or D: It is most likely that existing facilities would experience 

equipment switch-outs, upgrades, or expansions to meet increases in demand. The OCS oil- and 

gas-related activities that result from Alternative A, B, C, or D would contribute to the likelihood of 

0-1 new gas processing facilities.

3.1.7.3.1 Gas Processing Plants

All natural gas is processed in some manner to remove unwanted water vapor, solids, and/or 

other contaminants that would interfere with pipeline transportation or marketing of the gas. After 

processing, gas is then moved into a pipeline system for transportation to an area where it is sold. 

More than half (54%) of the natural gas processing plant capacity in the U.S. is located along the 

Gulf Coast and is available for supporting Federal offshore production (USDOE, Energy Information 

Administration, 2011). In the GOM region, the majority of gas processing plants are located in 

Louisiana (44) and Texas (39), followed by Alabama (13), Mississippi (1), and Florida (1) (Table 

3-4). While natural gas production on the OCS shelf (shallow water) has been declining, deepwater 

gas production has been increasing, but not at the same pace. Overall, the combined trends of 

increasing onshore shale gas development, declining offshore gas production, and increasing 

efficiency and capacity of existing gas processing facilities have lowered demands for new gas 

processing facilities along the Gulf Coast. Spare capacity at existing facilities should be sufficient to 

satisfy new gas production for many years, although there remains a slim chance that a new gas 
3-86 Gulf of Mexico Multisale EIS

processing facility may be needed by the end of the 50-year life of a proposed lease sale. 

Expectations for new gas processing facilities being built during the analysis period (2017-2066) are 

dependent on long-term market trends that are not easily predicable over the next 50 years 

(Dismukes, official communication, 2015).

Alternative A, B, C, or D: It is most likely that existing facilities would experience 

equipment switch-outs, upgrades, or expansions to meet increases in demand. The OCS oil- and 

gas-related activities that result from Alternative A, B, C, or D would contribute to the likelihood of 

0-1 new gas processing facilities.

3.1.7.3.2 Refineries

The U.S. Department of Energy’s Energy Information Administration updates national energy 

projections annually, including refinery capacity. Most of the GOM region’s refineries are located in 

Texas and Louisiana (Table 3-4). Texas EIAs contain 20 operable refineries, with an operating 

capacity of over 4.5 MMbbl/day, which is over 25 percent of the total U.S. capacity. Louisiana EIAs 

contain 16 operable refineries, with an operational capacity of over 3.2 MMbbl/day, which is over 

18 percent of the total U.S. capacity (USDOE, Energy Information Administration, 2015c). There 

has been a trend toward constructing simple refineries instead of complex refineries. In the United 

States, the last complex refinery started operating in 1977 in Garyville, Louisiana. In the GOM 

analysis area, a new simple refinery was constructed in 2014 in Galena Park, Texas (USDOE, 

Energy Information Administration, 2015d).

Alternative A, B, C, or D: No new facilities are expected to be constructed as a direct 

result of Alternative A, B, C, or D.

3.1.7.3.3 Onshore Liquefied Natural Gas Facilities

The wide variety of pipeline systems and delivery markets makes the GOM attractive for 

LNG developers. Onshore natural gas production has increased to the extent that LNG facilities 

along the GOM are seeking and receiving approval to export natural gas to foreign countries. There 

are six existing LNG import/export terminals in the GOM region—two in Texas, three in Louisiana, 

and one in Mississippi (USDOE, Federal Energy Regulatory Commission, 2015a). There are 

16 proposed LNG export terminals in the GOM region—8 in Texas, 7 in Louisiana, and 1 in 

Mississippi (USDOE, Federal Energy Regulatory Commission, 2015a). Facilities with export 

approval that are under construction are located in Sabine and Hackberry, Louisiana; and Freeport 

and Corpus Christi, Texas. Also approved for export but not yet under construction is Sabine Pass 

Liquefaction in Sabine Pass, Louisiana (USDOE, Federal Energy Regulatory Commission, 2015a). 

In 2014, New Orleans-based Harvey Gulf International Marine began construction of an LNG 

bunkering facility at Port Fourchon, Louisiana. The first of its kind in the United States, the LNG 

facility will provide LNG fuel to the growing supply of LNG-operated vessels servicing the OCS, as 

well as over-the-road vehicles fueled by LNG (Schuler, 2014).
Impact-Producing Factors and Scenario 3-87

Alternative A, B, C, or D: BOEM projects that expansions at existing facilities and 

construction of new facilities would not occur as a direct result of Alternative A, B, C, or D. Any 

expansions or new facilities would be the result of onshore rather than offshore production.

3.1.7.3.4 Petrochemical Plants

Petrochemical plants are usually located in areas with close proximity to the raw material 

supply (petroleum-based) and multiple transportation routes, including rail, road, and water. Texas, 

New Jersey, Louisiana, North Carolina, and Illinois are the top domestic chemical producing states. 

However, most of the basic chemical production is concentrated along the Gulf Coast where 

petroleum and natural gas feedstock are available from refineries. Of the top 10 production 

complexes in the world, 5 are located in Texas and 1 is located in Louisiana.

Along the Gulf Coast, the petrochemical industry is heavily concentrated in coastal Texas 

and south Louisiana and in various counties along the Alabama, Mississippi, and Florida coasts. 

The vast majority of petrochemical plants in the Gulf region are located along coastal Texas (126) 

and south Louisiana (66). Table 3-4 provides the numerical distribution for each state in the 

analysis area, and Figure 3-10 illustrates the geographical distribution of petrochemical facilities 

across the 133 Gulf counties and parishes within analysis area.

Alternative A, B, C, or D: No new facilities are expected to be constructed as a direct 

result of Alternative A, B, C, or D.

3.1.8 Air Emissions

Section 328(a) of the 1990 Clean Air Act Amendments gives the USEPA air quality 

responsibility for the OCS area in the Gulf of Mexico east of 87.5o W. longitude, and BOEM retains 

air quality jurisdiction for OCS operations west of the same longitude in the Gulf of Mexico. In 

addition, Section 328(b) of the Clean Air Act Amendments requires BOEM to assure coordination of 

air-pollution control regulations between the Gulf of Mexico OCS emissions and emissions in 

adjacent onshore areas. The Clean Air Act Amendments requires the USEPA to set the NAAQS 

and to periodically review and update the standards, as necessary, to ensure they provide adequate 

health and environmental protection. Consequently, there will be a continuing need for emission 

inventories and modeling whenever the USEPA updates the NAAQS.

The Outer Continental Shelf Lands Act (43 U.S.C. § 1334(a)(8)) tasks the U.S. Department of 

the Interior to assure that air pollutant emissions from offshore oil and gas exploration, development, 

and production sources do not significantly affect the air quality of any state. In particular, BOEM is 

responsible for determining if air pollutant emissions from offshore oil and gas activities in the Gulf of 

Mexico influence the NAAQS compliance status of Texas, Louisiana, Mississippi, Alabama, and 

Florida. BOEM’s air quality regulations in 30 CFR §§ 550.302, 550.303, and 550.304 were 

promulgated as mandated by Section 5(a)8 of the OCSLA; however, since the 1990 Clean Air Act 

Amendments transferred jurisdiction to the USEPA, BOEM’s regulations no longer apply to air 
3-88 Gulf of Mexico Multisale EIS

emission sources in OCS areas where the USEPA has jurisdiction. To assess offshore oil- and gasrelated activities and their associated emissions, BOEM conducted a series of studies. BOEM 

conducted a series of studies. BOEM has published the following study documents: in 1995, the 

Gulf of Mexico Air Quality Study (System Applications International et al., 1995); in 2004, the 

Gulfwide Emission Inventory Study for the Regional Haze and Ozone Modeling Effort (Wilson et al., 

2004) and the Data Quality Control and Emissions Inventories of OCS Oil and Gas Production 

Activities in the Breton Area of the Gulf of Mexico (Billings and Wilson, 2004); in 2007, the Year 2005 

Gulfwide Emission Inventory Study (Wilson et al., 2007); and in 2010, the Year 2008 Gulfwide 

Emission Inventory Study (Wilson et al., 2010). Due to new and updated NAAQS, drilling in deep 

water, and offshore sources changing because of new technology, BOEM continues to update the 

emissions inventories every 3 years to coincide with the USEPA and State agency inventory 

process. Since the emission inventories also include greenhouse gas emissions, OCS operators 

can use the data to report their greenhouse gas emissions to the USEPA.

To build on the previously conducted studies, BOEM completed the Year 2011 Gulfwide 

Emission Inventory Study (Wilson et al., 2014) with a goal of having a calendar year 2011 inventory 

air pollution emissions for all OCS oil and gas production-related sources in the Gulf of Mexico. 

Pollutants covered in this inventory are the criteria pollutants such as carbon monoxide (CO), 

nitrogen oxides (NOx), particulate matter (PM), and sulfur dioxide (SO2); and volatile organic 

compounds (VOCs), as well as major greenhouse gases such as carbon dioxide (CO2), methane 

(CH4), and nitrous oxide (N2O). Ozone (O3), a criteria pollutant, is formed by photochemical 

reactions of NOx and VOC in the atmosphere. Although ozone is not covered in this inventory, 

ozone precursors (NOx and VOCs) are covered. Lead (Pb), another criteria pollutant, is not covered 

in this inventory due to the lack of credible emission factors for this pollutant. Benzene, toluene, 

ethylbenzene, and xylene (BTEX) is a category of VOCs that occur naturally in crude oil, as well as 

during the process of making gasoline and other fuels from crude oil. Although BTEX is not 

individually addressed in this inventory, VOCs are covered.

The Year 2011 Gulfwide Emission Inventory Study presents a full description of monthly 

activity data from platform and non-platform sources, and it additionally updates those procedures 

used in previous inventories by taking the most recent emission factors from the USEPA and the 

Emission Inventory Improvement Program to develop a comprehensive criteria pollutant and 

greenhouse gas emissions inventory. A Year 2014 Gulfwide Emission Inventory Study, which is 

currently in progress, is built upon previous studies to develop a base year 2014 air pollution 

emissions inventory for all OCS oil and gas production-related sources in GOM. Furthermore, the 

study will cover well stimulation vessels and develop hazard air pollutant emission estimates for 

select oil and natural gas production platform emission sources.

3.1.8.1 Drilling

Refer to Chapter 3.1.3.1 for the description of drilling operations and activities. Refer to 

Chapter 4.1.2 and Figures 4-9 and 4-10 for emissions in tons per year for criteria pollutants and 

greenhouse gases from these activities. Emissions associated with drilling from OCS oil- and gas-
Impact-Producing Factors and Scenario 3-89

related activities are attributed to gasoline, diesel, and natural gas fuel usage in engines such as 

propulsion engines, prime engines, mud pumps, draw works, and emergency power. Pollutants 

emitted during drilling activities include combustion gases (i.e., CO, NOx, PM, SO2, CO2, CH4, and 

N2O) and VOCs. To understand further how emissions criteria pollutants are estimated, refer to NTL 

2008-G04, “Information Requirements for Exploration Plans and Development Operations 

Coordination Documents.”

3.1.8.2 Production

Refer to Chapter 3.1.3.1 for the description of production operations and activities. 

Emissions associated with production from OCS oil- and gas-related activities are attributed to 

boilers, diesel engines, combustion flares, fugitives, glycol dehydrators, natural gas engines, 

turbines, pneumatic pumps, pressure/level controllers, storage tanks, cold vents, and others. 

Pollutants emitted during production activities include CO, NOx, PM, SO2, VOCs, CO2, CH4, and 

N2O.

3.1.8.3 Vessel Support Operations and Activities during Offshore Oil and Gas Activities

Refer to Chapter 3.1.4.4 for the description of vessel support operations and activities during 

OCS oil- and gas-related activities. Emissions associated with support vessels from OCS oil- and 

gas-related activities are attributed to the operations of the primary diesel engine used for propulsion 

and other smaller diesel engines that are used to run generators or small cranes and winches for 

loading and unloading the vessels. Pollutants emitted during drilling activities include combustion 

gases (CO, NOx, PM, SO2, CO2, CH4, and N2O) and VOCs. For more information on service 

vessels, refer to Chapter 3.1.4.4. 

3.1.8.4 Flaring and Venting

The availability of a flare or vent is essential in oil and gas operations, primarily for safety 

reasons. It ensures that associated natural gas can be safely disposed of in emergency and 

shutdown situations.

Flaring is the controlled burning of natural gas and is a common practice in oil and gas 

exploration, production, and processing operations. The burning occurs at the end of a stack or 

boom. Flares generate heat and noise. Pollutants emitted during flaring include CO, NOx, PM, SO2, 

VOCs, CO2, CH4, and N2O.

Venting is the controlled release of unburned gases into the atmosphere in the course of oil 

and gas production operations. In venting, the natural gases associated with oil production are 

released directly into the atmosphere and not burned. Vents produce less noise and are less visible. 

Pollutants emitted during venting include VOCs, CO2, and CH4. 

Flaring and venting can have environmental impacts. Flaring may involve the disposal of 

sweet gas or sour gas. Sweet gas is natural gas that does not contain hydrogen sulfide (H2S) while 
3-90 Gulf of Mexico Multisale EIS

sour gas is natural gas that does contain H2S. Flaring produces predominantly CO2 emissions, while 

venting produces predominantly CH4 emissions. Both carbon dioxide and methane are known as 

greenhouse gases associated with concerns about global warming. The global warming potential of 

a kilogram of methane is estimated to be 21 times that of a kilogram of carbon dioxide when effects 

are considered over 100 years. Therefore, flaring is often considered to be the preferred method to 

dispose of natural gas in oil and gas operations. Although the global warming potential of methane 

when compared with carbon dioxide usually suggests that flaring is a more environmentally 

attractive option than venting, neighbors of onshore oil and gas developments prefer venting 

because it is less visible and produces less noise. Flaring and venting systems are used to burn off 

waste gas and surplus gases, and they are also a safety means to protect process equipment, the 

system’s processes, and the environment. Therefore, the activities can be divided into routing 

flaring and venting, and nonroutine (emergency) flaring and venting. Flares usually operate 

continuously; however, some are used only for process upsets. Natural gas discharges via venting 

can be due to routine or emergency releases.

Routine Flaring and Venting

Routine flaring occurs on a regular basis due to the normal operations of a facility. Flares 

can be used routinely to control emissions from storage tanks, loading operations, glycol dehydration 

units, vent collection system, and amine units. Natural gas discharges via venting can be due to 

routine or emergency releases. Vents receive exhaust streams from miscellaneous sources, as well 

as manifold exhaust streams from other equipment on the same platform such as amine units, glycol 

dehydrators, loading operations, and storage tanks.

3.1.8.5 Fugitive Emissions

Fugitive emissions are leaks from sealed surfaces associated with process equipment. 

Leaks can occur from operating conditions (pressure, temperature, etc.), aging, deterioration of 

sealing devices, and equipment solidity. Specific fugitive source types include cold vents; 

hydrocarbon loading and unloading operations; and equipment components such as valves, flanges, 

connectors, pump seals, compressor seals, and open-ended lines. Pollutants emitted from fugitive 

emissions include VOCs and CH4. 

3.1.8.6 Greenhouse Gases

The gases that keep the solar heat budget in the lower atmosphere are called greenhouse 

gases. Naturally, the atmospheric layer close to the Earth surface partially captures the long wave 

radiation from the Sun and keeps the planet habitable. These gases include CO2, CH4, N2O, and a 

variety of manufactured chemicals. Greenhouse gases can be emitted from natural sources; others 

are anthropogenic, resulting from human activities.

In response to the FY 2008 Consolidated Appropriations Act, the USEPA issued 40 CFR 

part 98, which requires reporting of greenhouse gas emissions. Subpart C of the Green House Gas 

Reporting Rule requires operators to report greenhouse gas emissions from general stationary fuel 
Impact-Producing Factors and Scenario 3-91

Noise associated with OCS oil- and gas-related

exploration and development results from 

seismic surveys, the installation of structures, the 

operation of fixed structures such as offshore 

platforms and drilling rigs, the decommissioning 

and explosive severance of structures, and 

helicopter and service-vessel traffic.

combustion sources to the USEPA. Subpart W of the Greenhouse Gas Reporting Rule requires 

petroleum and natural gas facilities that emit 25,000 metric tons or more of CO2 equivalents (CO2e) 

per year to report emissions from equipment leaks and venting. Emissions associated with 

greenhouse gases from OCS oil- and gas-related activities are attributed to the combustion of fossil 

fuel, production and transportation of oil and natural gas, and equipment leaks. Pollutants emitted 

during these activities include CO2, CH4, N2O, and CO2e.

3.1.8.7 Decommissioning

Refer to Chapter 3.1.6 for the description of decommissioning operations and activities. 

Emissions associated with decommissioning from OCS oil- and gas-related activities are attributed 

to the exhaust of diesel engines from the vessels including mobile offshore work-over rigs and lift 

vessels involved in the removal of pipelines and field facilities. Pollutants emitted during 

decommissioning include combustion gases (CO2, NOx, CO, PM, SO2, CH4 and VOCs).

3.1.9 Noise

Acoustic sources can be described by 

their sound characteristics. For the regulatory 

process, they are generally divided into two 

categories: impulsive noise and nonimpulsive 

noise.

Impulsive Noise

Impulsive noises (e.g., explosives, 

airguns, and impact pile drivers) are generally considered powerful sounds with relatively short 

durations, broadband frequency content, and rapid rise times to peak levels.

Airguns produce an intense but highly localized sound energy that propagates throughout 

the water column, and they represent a noise source of acoustic concern. BOEM completed the 

Atlantic G&G Activities Programmatic EIS, which includes a detailed description of the seismic 

surveying technologies, energy output, and operations and which has appendices that provide 

details on marine mammal, sea turtle, and fish hearing (USDOI, BOEM, 2014a); these descriptions 

are hereby incorporated by reference.

Deepwater marine seismic surveys (refer to Chapter 3.1.2.1) direct low-frequency energy 

waves (generated by an airgun array) into the ocean floor and record the response of the reflected 

energy waves’ response from the subsurface. The firing times of the guns are staggered by 

milliseconds in an effort to make the farfield noise pulse as coherent as possible. In short, the intent 

of the airgun array is to have it emit a very symmetric packet of energy in a very short amount of 

time and with a frequency content that penetrates well into the earth at a particular location 

(Caldwell, 2001). In some airgun surveys (including WAZ), these sources are activated in sequence 

between source vessels. The noise generated by airguns is intermittent, with pulses generally less 
3-92 Gulf of Mexico Multisale EIS

than 1 second in duration. Airgun arrays produce noise pulses with very high peak levels. The 

pulses are a fraction of a second long and repeat every 10-15 seconds (this range is for all airgun 

arrays). In other words, while airgun arrays are by far the strongest sources of underwater noise 

associated with OCS oil- and gas-related activities, because of the short duration of the pulses, the 

total energy is limited (Gordon and Moscrop, 1996). Acoustic calibration for the National Science 

Foundation’s R/V Marcus Langseth and its seismic array, conducted work by Tolstoy et al. (2009) in 

the GOM, suggests that, for deep water (~5,249 ft; 1,600 m), the 180-decibel (dB) radius would 

occur at less than 0.6 mi (1 km) from the source, while in shallow waters (~164 ft; 50 m), the 180-dB 

radius would be considerably larger (e.g., ~0.7 mi; 1.1 km).

Nonimpulsive Noise

Nonimpulsive noise generally includes all other noise (e.g., sonars and vibratory pile drivers) 

and includes continuous anthropogenic noise (e.g., vessel noise).

Ambient noise is an important aspect to the marine habitat and is an efficient way to transmit 

energy through the ocean; therefore, many marine organisms have evolved to utilize this. It is also 

the sound field against which animal signals must be detected and is a result of both natural and 

anthropogenic noise sources. Anthropogenic noise is generally low-frequency (10 to 500 Hz), seasurface agitation falls within the medium-frequency range (500 Hz to 25 kHz), and high-frequency 

noise (>25 kHz) can be from thermal noise (Hildebrand, 2009). Anthropogenic noise is generated by 

many different activities, including shipping, fishing, boating, research, and activities related to oil 

and gas exploration, development, and production. The activities encompass areas that represent 

important marine habitat (Hildebrand, 2009). The OCS oil- and gas-related noise generated from 

these activities can be transmitted through both air and water, and may be long- or short-lived in 

time, distance, and sound level. The intensity level and frequency of the noise emissions are highly 

variable, both between and among the various types of sound sources. Noise from proposed OCS 

oil- and gas-related activities may affect resources near the activities.

It is generally recognized that commercial shipping is a dominant component of the ambient, 

low- and medium-frequency background noise in modern world oceans (Gordon and Moscrop, 1996) 

and that OCS oil- and gas-related, service-vessel traffic would contribute to this. Another sound 

source more specific to OCS operations originates from seismic operations.

Information on drilling noise in the GOM is unavailable to date. From studies mostly in 

Alaskan waters, drilling operations (these can include pile driving, generators, pumps, etc.) often 

produce noise that includes strong tonal components at low frequencies, including infrasonic 

frequencies in at least some cases. Drillships are noisier than semisubmersibles (Richardson et al., 

1995). Sound and vibration paths to the water are through either the air or the risers, in contrast to 

the direct paths through the hull of a drillship. This sound difference is due to the dynamic 

positioning systems on the drillships as compared with anchored MODUs. Richardson et al. (1995) 

stated that sound was measured at three ring-caisson sites in the Arctic. Sound was measured from 

the 20- to 1,000-Hz band levels at a range of 1.8 km (1.1 mi) at levels of 113-126 dB re: 1μPa 
Impact-Producing Factors and Scenario 3-93

(decibels referenced 1 microPascal). The received sound levels varied based on the activity of the 

support vessels. These estimated levels were higher than drilling activities on an artificial island but 

lower than on drillships (Richardson et al., 1995).

Machinery noise generated during the operation of fixed structures can be continuous or 

transient, and variable in intensity. Underwater noise from fixed structures ranges from about 20 to 

40 dB above background levels within a frequency spectrum of 30-300 Hz at a distance of 30 m 

(98 ft) from the source (Gales, 1982). These levels vary with type of platform and water depth. 

Underwater noise from platforms standing on metal legs would be expected to be relatively weak 

because of the small surface area in contact with the water and the placement of machinery on 

decks well above the water.

Aircraft and vessel support may further contribute to acoustic pollution around a production 

facility, as well as the transit area. Noise generated from helicopter and service-vessel traffic is 

transient in nature and extremely variable in intensity. Helicopter sounds contain dominant tones 

(resulting from rotors) generally below 500 Hz (Richardson et al., 1995). For example, a Bell 212 

helicopter may operate at a 22-Hz tone and have an estimated received level of 149 dB re: 1μPa 

(Richardson et al., 1995). Differences in the density sound speed of air and water reduce the sound 

that propagates into the water column from the air and generally restrict it to entry angles that are 

within about 11 degrees of perpendicular to the water’s surface. Helicopters often radiate more 

sound forward than backward; thus, underwater noise is generally brief in duration, compared with 

the duration of audibility in the air. In addition to the altitude of the helicopter, water depth and 

bottom conditions strongly influence propagation and levels of underwater noise from passing 

aircraft. Lateral propagation of sound is greater in shallow water than in deep water. Helicopters, 

while flying offshore, generally maintain altitudes above 700 ft (213 m) during transit to and from the 

working area and an altitude of about 500 ft (152 m) while between platforms.

Service vessels transmit noise through both air and water. The primary sources of vessel 

noise are propeller cavitation, propeller singing, and rotating machinery; other sources include 

auxiliaries, flow noise from water dragging along the hull, and bubbles breaking in the wake 

(Richardson et al., 1995). Propeller cavitation is usually the dominant noise source (broad band but 

with peak energy in low frequency). The intensity of noise from service vessels is roughly related to 

ship size, laden or not, and speed. Large ships tend to be noisier than small ones, and ships 

underway with a full load (or towing or pushing a load) produce more noise than empty vessels. For 

example, a 16-m (52-ft) crewboat may have a 90-Hz tone with a source level of 156 dB re: 1μPa, 

and a small ship may have a broadband source level of 170-180 dB re: 1μPa (Richardson et al., 

1995). For a given vessel, relative noise also tends to increase with increased speed. Commercial 

vessel noise is a dominant component of manmade ambient noise in the ocean (Jasny, 1999).

Stakeholders (mainly the NMFS, research institutions, and the U.S. Navy) have been in 

discussions about establishing specific criteria for thresholds on marine animal hearing to cause a 

temporary threshold shift or permanent threshold shift and determining behavioral effects. 

Previously, the 180 dB re-1 μPa-m level was an estimate of the threshold of sound energy that may 
3-94 Gulf of Mexico Multisale EIS

cause hearing damage in cetaceans (U.S. Dept. of the Navy, 2001). In 2012, the Navy updated their 

acoustic threshold criteria for marine mammals and sea turtles to similar criteria as those published 

by Southall et al. (2007). Those criteria are discussed in Chapters 4.9.2 and 4.9.5. Information on 

the acoustic environment and marine sound can also be found in Chapter 4.2.2 of the Five-Year 

Program EIS.

3.1.10 New and Unusual Technology

Technologies continue to evolve to meet the technical, environmental, and economic 

challenges of deepwater development. BOEM’s predecessor prepared a Programmatic EA to 

evaluate the potential effects of deepwater technologies and operations (USDOI, MMS, 2000b). As 

a supplement to the EA, BOEM’s predecessor prepared a series of reference document that 

provides a profile of the different types of development and production structures that may be 

employed in the GOM deep water (USDOI, MMS, 2000a). The Programmatic EA and technical 

papers were used in the preparation of this Multisale EIS. Additional technologies introduced since 

the publication of the EA in 2000 include WAZ (Chapter 3.1.2.1) and duel-gradient drilling. Duelgradient drilling uses seawater-density fluid in place of the mud that would normally flow through a 

well and uses dense mud at the bottom of the well to maintain bottom-hole pressure. This 

technology allows operators to reach reservoirs 40,000 ft (12,192 m) below the seafloor, a depth that 

is otherwise affected by water depth.

The operator must identify new or unusual technology, as defined in 30 CFR § 550.200, in 

exploration and development plans. Some of the technologies proposed for use by the operators 

are actually extended applications of existing technologies and interface with the environment in 

essentially the same way as well-known or conventional technologies. These technologies are 

reviewed by BOEM for alternative compliance or departures that may trigger additional 

environmental review. Some examples of new technologies that do not affect the environment 

differently and that are being deployed in the regionwide OCS Program are synthetic mooring lines, 

subsurface safety devices, and multiplex subsea controls.

Some new technologies differ in how they function or interface with the environment. These 

include equipment or procedures that have not been installed or used in Gulf of Mexico OCS waters. 

Having no operational history, they have not been assessed by BOEM through technical and 

environmental reviews. New technologies may be outside the framework established by BOEM’s 

regulations and, thus, their performance (i.e., safety, environmental protection, efficiency, etc.) has 

not been studied by BOEM. The degree to which these new technologies interface with the 

environment and the potential impacts that may result are considered in determining the level of 

NEPA review that would be initiated if an operator wishes to deploy it.

BOEM has developed a new and unusual technologies’ matrix to help facilitate decisions on 

the appropriate level of engineering and environmental review needed for a proposed technology. 

All projects in the GOM using nonconventional production or completion technology require a 

deepwater operations plan and a review by BSEE. Technologies will be added to the new and 
Impact-Producing Factors and Scenario 3-95

unusual technologies’ matrix as they emerge, and technologies will be removed as sufficient 

experience is gained in their implementation. From an environmental perspective, the matrix 

characterizes new technologies into three components: technologies that may affect the 

environment; technologies that do not interact with the environment any differently than 

“conventional” technologies; and technologies for which BOEM does not have sufficient information 

to determine its potential impacts to the environment. In this latter case, BOEM would seek to gain 

the necessary information from operators or manufacturers regarding the technologies in order to 

make an appropriate determination on its potential effects on the environment.

Alternative Compliance and Departures: When an OCS operator proposes the use of 

technology or procedures not specifically addressed in established BOEM regulations, the 

operations are evaluated for alternative compliance or departure determination. BOEM, in 

coordination with BSEE’s Technical Assessment Section, conducts a project-specific engineering 

safety review to ensure that equipment proposed for use is designed to withstand the operational 

and environmental condition in which it would operate. Any new technologies or equipment that 

represent an alternative compliance or departure from existing BOEM regulation must be fully 

described and justified before it would be approved for use. For BOEM to grant alternative 

compliance or departure approval, the operator must demonstrate an equivalent or improved degree 

of protection as specified in 30 CFR § 550.141. Comparative analysis with other approved systems, 

equipment, and procedures is one tool that BOEM uses to assess the adequacy of protection 

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

alternative compliance measures before BOEM/BSEE would consider them as proven technology.

In addition to new and unusual technology for drilling, as a result of the Deepwater Horizon

explosion, oil spill, and response, many technologies or applications were developed in an attempt to 

stop the spill and cap the well in any future accidents. The NTL 2010-N10, “Statement of 

Compliance with Applicable Regulations and Evaluation of Information Demonstrating Adequate 

Spill Response and Well Containment Resources,” applies to operators conducting operations using 

subsea BOPs or surface BOPs on floating facilities. BOEM would assess whether each lessee has 

submitted adequate information demonstrating that it has access to and can deploy surface and 

subsurface containment resources that would be adequate to promptly respond to a blowout or other 

loss of well control. Containment resources could consist of, but are not limited to, subsea 

containment and capture equipment including containment domes and capping stacks, subsea utility 

equipment including hydraulic power, hydrate control, and dispersion injection equipment. 

3.2 IMPACT-PRODUCING FACTORS AND SCENARIO—ACCIDENTAL EVENTS

3.2.1 Oil Spills

As a consequence of activities related to the exploration, development, production, and 

transportation of oil and gas, the potential for accidental releases exists. Input through public 

scoping meetings, Federal and State agency consultation and coordination, and industry and 

nongovernmental organizations’ comments indicate that stakeholders continue to have concerns 

about oil spills and the threat they pose to the environment. Although oil-spill occurrence cannot be 
3-96 Gulf of Mexico Multisale EIS

predicted, an estimate of its likelihood can be quantified using spill rates derived from historical data 

and projected volumes of oil production and transportation. The following chapters discuss the 

history of oil spills in the GOM, the processes that affect spilled oil, and a risk analysis for spills that 

may be reasonably foreseeable as a result of Alternative A, B, C, or D, as well as information on the 

number and size of spills from non-OCS oil- and gas-related sources. Under Alternative D, the 

number of blocks that would become unavailable for lease represents only a small percentage (<4%) 

of the total number of blocks to be offered under Alternative A, B, or C. Therefore, Alternative D 

could reduce offshore infrastructure by up to 4 percent when chosen in conjunction with Alternative 

A, B, or C. However, it is also possible that Alternative D would only shift the location of offshore 

infrastructure and activities farther from sensitive topographic zones and not lead to a reduction in 

offshore infrastructure and activities. Refer to Chapter 2.2.2.4 for more information on Alternative D. 

For an analysis of a low-probability catastrophic spill, which is not reasonably foreseeable as a result 

of a proposed action or the alternatives, refer to the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2016c).

3.2.1.1 Past OCS Spills

3.2.1.1.1 Trends in Reported Spill Volumes and Numbers

A summary of reported spill incidents is available from the USCG in a report entitled Polluting 

Incidents In and Around U.S. Waters, A Spill/Release Compendium: 1969-2011 (U.S. Dept. of 

Homeland Security, CG, 2012). The data include reports of all releases involving oil and hazardous 

substances from various sources, including barges, tanks, pipelines, and waterfront facilities. A 

review of the information shows that the majority of spills are ≤1 bbl. Additionally, the overall number 

and volume of spills in U.S. waters has been on a downward trend since 1973. The number and 

volume of oil spilled in the Gulf of Mexico from 2001 through 2015 is presented in Table 3-11. 

Table 3-11. Annual Summary of Number and Total Volume of Oil 

Spilled into the Gulf of Mexico, 2001-20151

Year Number of Spills Volume bbl (gallons)

2001 1,728 3,187 (133,872)

2002 733 2,535 (106,465)

2003 801 1,181 (49,617)

2004 908 760 (31,935)

2005 804 44,141 (1,853,919)

2006 868 2,947 (123,788)

2007 616 1,560 (65,511)

2008 523 355 (14,928)

2009 454 212 (8,898)

2010 455 4,928,389 (206,992,317)1

2011 498 483 (20,276)

2012 801 241 (10,136)

2013 848 314 (13,212)

2014 694 902 (37,889)

20152 753 1,164 (48,884)
Impact-Producing Factors and Scenario 3-97

Year Number of Spills Volume bbl (gallons)

Note: The volume reported does not include oil spilled in rivers that 

enters the Gulf of Mexico. The reported spills include both crude 

and refined products.

1 These data include the Deepwater Horizon oil spill (4,928,198 bbl). 

(Note: For purposes of calculating the maximum possible civil penalty 

under the Clean Water Act, a January 2015 judgement used a quantity 

of 4.0 million barrels of oil for total discharged and 3.19 million barrels 

of oil as the actual amount that was released into environment [Barbier 

and Shushan, 2015]).

2 Through August 5, 2015.

Source: U.S. Dept. of Homeland Security, CG, 2015a.

Etkin (2009) examined spills in the United States related to both onshore and offshore 

activities. Between 1998 and 2007 all of the oil spilled from offshore platforms occurred on the OCS 

in Federal waters. No spills from platforms in State waters were reported. Among these spills, the 

volume was about equally divided between crude oil and diesel fuel. However, the amount of diesel 

spilled in 2005 was three times greater than the amount spilled in any other year due to the 

hurricanes that occurred in the GOM. From 1998 through 2007 an average of 1,273 bbl of oil/year 

spilled from GOM platforms and 2,613 bbl of oil/year spilled from GOM pipelines. Only about 10 bbl 

of oil/year spilled from vessels that supply the offshore industry during the same 10-year interval.

The most common causes of spill incidents were hurricane-related, and the relative volumes 

associated with offshore platform incidents for the decade 1998 through 2007 were as follows:

Causes of Spills Percentage 

of Incidents

Percentage 

of Spill Volume

Hurricanes 47% 85%

Structural Failure 

(such as corrosion) 26% 4%

Operator Error 18% 8%

The most common causes for pipelines were also hurricane-related, and the relative 

volumes of pipeline spills during this same 10-year period were as follows:

Causes of Spills Percentage 

of Incidents

Percentage 

of Spill Volume

Hurricanes 58% 43%

Structural Failure 29% 41%

Vessel Damage 

(such as anchor drag) 5% 15%

It was estimated that, between 1998 and 2007, 1,200 bbl of oil was spilled per billion barrels 

of oil produced and that offshore platforms and pipelines spilled 3,887 bbl of oil per year.
3-98 Gulf of Mexico Multisale EIS

Previous work by Anderson and LaBelle (1990, 1994, and 2000) provided estimates of oilspill occurrence rates expressed and normalized in terms of the number of spills per volume of crude 

oil handled. This work was updated in Anderson et al. (2012) and utilized United States’ OCS 

platform and pipeline spill data from 1964 through 2010. Platform and pipeline spills included both 

crude oil and condensate, but platform spills may also include refined products such as diesel fuel. 

The report utilized the spill record from 1964 through 2010 but also examined shorter intervals to 

identify trends and also to show how the Deepwater Horizon explosion, oil spill, and response 

influenced the spill statistics. The report notes several additional factors that have influenced spill 

rates, including six highly destructive hurricanes between 2002 and 2008 that destroyed or 

extensively damaged 305 platforms, 76 drilling rigs, and over 1,200 pipeline segments, and the 

inclusion of “passive spills” or petroleum missing based on pre-storm platform inventories. Overall, 

the spill rates of ≥1,000 bbl for OCS platforms declined during the most recent 15-year period 

analyzed. During this period, two platform spills occurred: Hurricane Rita in 2005 and the 

Deepwater Horizon oil spill in 2010. Prior to the Deepwater Horizon oil spill, the last United States’ 

OCS platform spill ≥10,000 bbl occurred in 1970. Spill rates of ≥1,000 bbl for OCS pipelines also 

declined during the most recent 15-year period with seven spills of ≥1,000 bbl and zero spills 

≥10,000 bbl. The last reported OCS pipeline spill ≥10,000 bbl occurred in 1990 (Table 3-12).

Table 3-12. Spill Rates for Petroleum Spills ≥1,000 Barrels from OCS Platforms and Pipelines, 

1964 through 2010.

Spill Size 

and 

Source

Previous Rate, 1964-1999 Updated Rate, 1964-2010 Current Rate, 1996-2010

Volume 

Handled 

(Bbbl)

Number 

of Spills

Spill 

Rate

Volume 

Handled 

(Bbbl)

Number 

of Spills

Spill 

Rate

Volume 

Handled 

(Bbbl)

Number 

of Spills

Spill 

Rate

≥1,000 bbl

Platforms 9.5 of 12.0 3 of 11 0.32 15.8 of 18.1 5 of 13 0.32 8.0 2 0.25

Pipelines 12.0 16 1.33 9.6 of 18.1 9 of 20 0.94 8.0 7 0.88

≥10,000 bbl

Platforms 12.0 4 0.12 15.8 of 18.1 1 of 5 0.06 8.0 1 0.13

Pipelines 12.0 4 0.33 9.6 of 18.1 – 0.19 8.0 – 0.18

Source: Anderson et al., 2012.

3.2.1.1.2 Coastal Spills

Coastal spills are defined here as spills in State offshore waters and spills in navigation 

channels, rivers, and bays from barges and pipelines carrying OCS-produced oil. These spills occur 

at shoreline storage, processing, and transport facilities supporting the OCS oil and gas industry and 

could be spills of crude oil or spills of fuel oil used in vessels. Many reports of spills cannot be traced 

back to the source or type of oil and are recorded as unknown. Similarly, for these small spills of 

unknown oil, the volume is also likely to be an estimate. Records of spills in coastal waters and 

State offshore waters are maintained by the USCG (USDHS, CG, 2015a). The source may be 

recorded, for example, as an offshore pipeline, but the database does not identify the source of the 

oil in the pipeline (OCS versus non-OCS domestic). A pipeline carrying oil from a shore base to a 

refinery may be carrying oil from both State and OCS production; imported oil might also be 
Impact-Producing Factors and Scenario 3-99

commingled in the pipeline. The USCG also records the type of oil spilled and whether it is crude oil, 

a refined product such diesel fuel or heavy fuel oil, or a type of commodity in transport, such as 

vegetable oil. The USCG data have some shortcomings that should be noted. For spills of unknown 

source, the caller may guess as to what type of oil, crude, or fuel was released. The database 

includes a latitude and longitude GPS (global positioning system) position for each spill, as well as a 

verbal description of location. The verbal description may not match the position. For example, the 

verbal description could be Mississippi Sound, but the GPS position is actually on the OCS. For this 

report, the GPS position was used, not the verbal description of the location.

BOEM pays special attention to spills related to exploration and production that occur on 

Federal leases in OCS waters, i.e., the submerged lands, subsoil, and seabed lying between the 

seaward extent of the State’s jurisdiction and the seaward extent of Federal jurisdiction. BOEM 

does not maintain comprehensive data on spills that have occurred in the State’s jurisdiction. 

Although BSEE has occasionally collected information on State pollution incidents, there is no 

database available that contains only past spills that have occurred in State offshore or coastal 

waters solely and directly as a result of OCS oil and gas development.

Therefore, coastal spill data from all potential spillage sources were searched using the 

USCG database for the most recent 12 years, January 2002-April 2014 (USDHS, CG, 2015a) in 

order to obtain information on spills that have occurred in State offshore or coastal waters, most 

probably as a result of oil and gas development. In order to search the data, the USCG data were 

examined using the latitude and longitude provided in the spill report, which resulted in some of the 

reported locations that fell inland or outside of the GOM being omitted. Some broad assumptions 

were made in the use of these data. State offshore waters are defined here as the portion of the 

GOM under State jurisdiction that begins at the coastline and ends at the Federal/State boundary 

9 nmi (10.36 mi; 16.67 km) offshore Texas; 3 nmi (3.5 mi; 5.6 km) offshore Louisiana, Mississippi, 

and Alabama; and 9 nmi (10.36 mi; 16.67 km) offshore Florida. For the purpose of comparing spill 

events across GOM coastal waters, spills in rivers, estuaries, and bays, and 0-3 nmi (0-3.45 mi; 

0-5.56 km) from shore were counted as coastal spills. The number of GOM coastal spills from five 

sources associated with State or Federal offshore production and international importation was 

determined from the data (Table 3-13). Louisiana and Texas have extensive oil and gas activity 

occurring in their territorial seas, as well as in Federal waters on the OCS. The sources that were 

counted are fixed platforms, MODUs, OSVs, offshore pipelines, and tank ships or barges. Although 

counts for tank ships and barges are shown as sources, the amount of barged and tankered GOM 

oil production is limited; therefore, these numbers are conservatively high as they include all of the 

oil tankered or barged. BOEM shows that 96 percent of OCS oil- and gas-related activity spills are 

<1 bbl, with an average size of 0.05 bbl, and that 4 percent of OCS oil- and gas-related activity spills 

are 1-999 bbl, with an average size of 77 bbl (Anderson et al., 2012).
3-100 Gulf of Mexico Multisale EIS

Table 3-13. Historic Spill Source, Location, and Characteristics of a Maximum Spill for Coastal Waters1

and Offshore Waters2

 (data extracted from USDOT, CG records, 2002-20143).

Source

Number of Spills Maximum Volume of a Single Incident

Total 

Number of 

Spill Events

Number 

of Spills 

(<1,000 bbl)

Number 

of Spills 

(≥1,000 bbl)

Volume (bbl) of 

Maximum Spill 

from the Source 

Maximum Spill Amount 

Source/Product/Year

Western Planning Area (WPA)2

Fixed Platform 251 251 0 3 Fixed Platform/Chemical/ 

2013

Pipeline 2 2 0 0.08 Offshore Pipeline/Oil/ 

2007

MODU 16 16 0 938 MODU/Chemical/2013

OSV 19 19 0 12 OSV/Oil/Unknown

Tank Ship or 

Barge 11 11 0 43 Tank Barge/Oil/2003

Total 2 2 0 – –

Central Planning Area (CPA)2

Fixed Platform 3,568 3,567 1 1,137 Fixed Platform/Chemical/ 

2003

Pipeline 8 8 0 5 Pipeline/Oil/2005

MODU 248 245 3 4,928,198 MODU/Oil/2010

OSV 183 183 0 350 OSV/Chemical/2002

Tank Ship or 

Barge 18 17 1 unknown Tank Ship/Chemical/2010

Total 8 8 5 – –

Eastern Planning Area (EPA)2

Fixed Platform 6 6 0 5 Fixed Platform/Oil/2007

Pipeline 0 0 0 0 –

MODU 1 1 0 0.12 MODU/Unknown

OSV 0 0 0 0 –

Tank Ship or 

Barge 0 0 0 0 – 

Total 7 0 0 – –

Coastal Waters: Texas

Fixed Platform 72 72 0 3 Fixed Platform/Unknown

Pipeline 0 0 0 N/A N/AMODU 9 9 0 0.05 MODU/Unknown

OSV 6 6 0 3 OSV/Oil/2003

Tank Ship or 

Barge 6 6 0 12 Tank Ship/Oil/2004

Total 93 93 0 – –
Impact-Producing Factors and Scenario 3-101

Source

Number of Spills Maximum Volume of a Single Incident

Total 

Number of 

Spill Events

Number 

of Spills 

(<1,000 bbl)

Number 

of Spills 

(≥1,000 bbl)

Volume (bbl) of 

Maximum Spill 

from the Source 

Maximum Spill Amount 

Source/Product/Year

Coastal Waters: Louisiana

Fixed Platform 1,437 1,436 1 1,200 Fixed Platform/Oil/2007

Pipeline 4 4 0 0.7 Pipeline/Oil/2013

MODU 11 11 0 62 MODU/Oil/2002

OSV 32 32 0 12 OSV/Oil/2002

Tank Ship or 

Barge 9 9 0 10 Deck Barge/Oil/2003

Total 1,493 1,492 1 – –

Coastal Waters: Mississippi

Fixed Platform 4 4 0 0.0.024 Fixed Platform/Oil, 

Misc:Motor/2000

Pipeline 0 0 0 N/A NA

MODU 0 0 0 N/A N/A

OSV 0 0 0 N/A N/A

Tank Ship or 

Barge 0 0 0 N/A N/A

Total 4 4 0 – –

Coastal Waters: Alabama

Fixed Platform 10 10 0 0.5 Fixed Platform/Oil/2004

Pipeline 0 0 0 N/A N/A

MODU 1 1 0 0.05 MODU/Unknown

OSV 3 3 0 0.02 OSV/Oil/2008

Tank Ship or 

Barge 1 1 0 01 Cutter/Dredger Barge/Oil/ 2011

Total 15 15 0 – –

Coastal Waters: Florida

Fixed Platform 3 3 0 0.095 Fixed Platform/Unknown

Pipeline 0 0 0 N/A N/A

MODU 0 0 0 N/A N/A

OSV 1 1 0 10 OSV/Oil/2009

Tank Ship or 

Barge 1 1 0 4 Bulk Liquid Cargo (Tank)/Oil/2003

Total 5 5 0 – –
3-102 Gulf of Mexico Multisale EIS

bbl = barrel; MODU = mobile offshore drilling unit; N/A = not applicable; OSV = offshore support vessel.

Note: The reader should note that the spills are reported to the USCG by responsible parties, other 

private parties, and government personnel. The USCG does not verify the source or volume of 

every report.

1

Coastal Waters – 0-3 nmi (0-3.5 mi; 0-5.6 km) from the coastline and spills in rivers, lakes, bays, and 

estuaries.

2

Offshore Waters, WPA, CPA, and EPA – Spills that occurred in water depths 3 nmi (3.5 mi; 5.6 km) 

from the coastline to the OCS planning area boundary.

3

The database included represents spill events from January 2002 until April 2014.

3.2.1.2 Offshore Spills

Petroleum spills from OCS oil- and gas- related activities include crude oil, condensate, and 

refined products such as diesel, hydraulic oil, lube oil and mineral oil. For spills of synthetic oil 

products, drilling muds, or chemicals, refer to Chapter 3.2.6. 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. Oil-spill 

information comes from a variety of sources. The BSEE requires operators to report any spill ≥1 bbl 

occurring on the OCS and maintains a database for all reported incidents. Not included in BSEE’s 

data records are spills <1 bbl. Spills of any size and composition are required to be reported to the 

USCG’s National Response Center and are documented in the USCG’s Marine Information for 

Safety and Law Enforcement (2001-present) database and its predecessors. Also not included in 

BSEE’s database are spills that have occurred in Federal waters from OCS barging operations and 

from other service vessels that support the OCS oil and gas industry. These data are included in the 

USCG record of all spills; however, the USCG database does not include the source of oil (OCS 

versus non-OCS) or in the case of spills from vessels, the type of vessel operations; such 

information is needed to determine if a particular spill occurred as a result of OCS operations. Spills 

from vessels are provided for tankers in worldwide waters and tankers and barges in U.S. coastal 

and offshore waters. The latter is a subset of the spills included in the worldwide tanker spill data. 

These data identify whether the spill occurred “at sea” or “in port’ as they can occur due to mishaps 

during loading, unloading, and taking on fuel oil, and from groundings, hull failures, and explosions. 

Table 3-14 and 3-15 provide information on OCS spills ≥1,000 bbl that have occurred offshore in the 

GOM for the period from 1964 through 2015. No spill >1,000 bbl has occurred since the Deepwater 

Horizon oil spill.
Impact-Producing Factors and Scenario 3-103

Table 3-14. Petroleum1 Spills ≥1,000 Barrels from United States OCS2 Platforms, 1964-2015.

Date

Leasing 

Area3

 

and Block 

Number

Water 

Depth 

(ft)

Distance 

to Shore 

(mi)

Volume 

Spilled 

(bbl)

Operator Facility or Structure 

and Cause of Spill

4/08/1964 EI 208 94 48 2,559 Continental

Oil

Freighter struck Platform A: fire,

platform and freighter damaged

10/03/1964 Hurricane 

Hilda 11,8694 Event Total 5 platforms destroyed duringHurricane Hilda

EI 208 94 48 5,180 Continental

Oil

Platforms A, C, and D destroyed: 

blowouts (several days)

SS 149 55 33 5,100 Signal O & G Platform B destroyed: blowout 

(17 days)

SS 199 102 44 1,589 Tenneco Oil Platform A destroyed: lost 

storage tank

7/19/1965 SS 29 15 7 1,6885 PanAmerican Well #7 drilling: blowout

(8 days), minimal damage

1/28/1969

6B 5165

Santa 

Barbara 

Channel, 

California

190 6 80,000 Union Oil

Well A-21 drilling: blowout

(10 days), 50,000 bbl during

blowout phase, subsequent

seepage of 30,000 bbl (over

decades), 4,000 birds killed, 

considerable oil on beaches, 

platform destroyed

3/16/1969 SS 72 30 6 2,500 Mobil Oil

Submersible rig Rimtide drilling in

heavy seas bumped by supply 

vessel

2/10/1970 MP 41 39 14 65,0006 Chevron Oil

Platform C: rig shifted and

sheared wellhead, blowout

(3-4 days), fire of unknown origin,

blowout 12 wells (49 days), lost 

platform, minor amounts of oil on

beaches

12/1/1970 ST 26 60 8 53,000 Shell Oil

Platform B: wireline work, gas

explosion, fire, blowout

(138 days), lost platform and

2 drilling rigs, 4 fatalities, 

36 injuries, minor amounts of oil

on beaches

1/09/1973 WD 79 110 17 9,935 Signal O & G Platform A: oil storage tank

structural failure

1/26/1973 PL 23 61 15 7,000 Chevron Oil Platform CA: storage barge sank

in heavy seas

11/23/1979 MP 151 280 10 1,5007 Texoma 

Production

MODU Pacesetter III: diesel tank

holed, workboat contact in heavy 

seas
3-104 Gulf of Mexico Multisale EIS

Date

Leasing 

Area3

 

and Block 

Number

Water 

Depth 

(ft)

Distance 

to Shore 

(mi)

Volume 

Spilled 

(bbl)

Operator Facility or Structure 

and Cause of Spill

11/14/1980 HI 206 60 27 1,456 Texaco Oil

Platform A: storage tank

overflow during Hurricane

Jeanne evacuation

9/24/2005 Hurricane 

Rita 5,0668 Event Total 1 platform and 2 rigs destroyedby Hurricane Rita

EI 314 230 78 2,0005 Forest Oil Platform J: destroyed, lost oil on 

board and in riser

SM 146 238 78 1,4949 Hunt

Petroleum

Jack-up Rig Rowan Fort Worth: 

swept away, never found

SS 250 182 69 1,5729 Remington O 

& G

Jack-up Rig Rowan Odessa: 

legs collapsed

04/20/2010 MC 252 4,992 53 4.9 

million10 BP E & P 

Deepwater Horizon Rig: gas

explosion, blowout (86 days to

cap well), fire, drilling rig sank, 

11 fatalities, multiple injuries, 

considerable oil on beaches, 

wildlife affected, temporary 

closure of area fisheries

Notes: barrel (bbl) = 42 gallons, billion = 109; MODU = mobile offshore drilling unit

Between 1964 and 2009, over 17.5 billion bbl of oil and 176.1 Mcf of natural gas were produced 

on the OCS.

1

Crude oil release unless otherwise noted; no spill contacts to land unless otherwise noted.

2

Outer Continental Shelf (OCS) – submerged lands, subsoil, and seabed administered by the U.S. 

Federal Government (http://www.boem.gov/Governing-Statutes/).

3

Gulf of Mexico leasing area unless otherwise noted (official protraction diagrams, 

http://www.boem.gov/Official-Protraction-Diagrams/): EI = Eugene Island, HI = High Island, 

MC = Mississippi Canyon, MP = Main Pass, PL = South Pelto, SS = Ship Shoal, SM = South Marsh 

Island, ST = South Timbalier, and WD = West Delta.

4

Hurricane Hilda, 10/3/1964: platform spills ≥1,000 bbl at 3 facilities totaled 11,869 bbl; treated as 1 spill 

event.

5

Condensate – a liquid product of natural gas production.

6

Spill volume estimate between 30,000 and 65,000 bbl, previously reported as 30,000 bbl.

7

Diesel fuel.

8

Hurricane Rita, 9/24/2010: platform and 2 rig losses ≥1,000 bbl at 3 locations totaled to 5,066 bbl; 

treated as 1 spill event. The 5,066-bbl spill was a “passive” spill based on unrecovered pre-storm 

inventories from the platform and 2 rigs; no spill observed; no response required.

9

Diesel fuel and other refined petroleum products stored on rig.

10The Federal Interagency Solutions Group, 2010. (Note: For purposes of calculating the maximum 

possible civil penalty under the Clean Water Act, a January 2015 judgement used a quantity of 

4.0 million barrels of oil for total discharged and 3.19 million barrels of oil as the actual amount that was 

released into environment [Barbier and Shushan, 2015]).

Sources: Anderson et al., 2012; U.S. Dept. of Homeland Security, CG, 2015a.
Impact-Producing Factors and Scenario 3-105

Table 3-15. Petroleum1 Spills ≥1,000 Barrels from United States OCS2 Pipelines, 1964-2015.

Date

Leasing 

Area3

and 

Block 

Number

Water 

Depth 

(ft)

Distance 

to Shore 

(mi)

Volume 

Spilled 

(bbl)

Operator Pipeline Segment (pipeline authority4

) 

Cause/Consequences of Spill

10/15/1967 WD 73 168 22 160,638 Humble 

Pipeline

12" oil pipeline, Segment #7791 (DOT): 

anchor kinked, corrosion, leak

3/12/1968 ST 131 160 28 6,000 Gulf Oil 18" oil pipeline, Segment #3573 (DOT): 

barge anchor damage

2/11/1969 MP 299 210 17 7,532 Chevron 

Oil

4" gas pipeline, Segment #3469 (DOT): 

anchor damage

5/12/1973 WD 73 168 22 5,000 Exxon 

Pipeline

16" gas & oil pipeline, Segment #807

(DOT): internal corrosion, leak

4/17/1974 EI 317 240 75 19,833 Pennzoil 14" oil Bonita pipeline, Segment #1128

(DOI): anchor damage

9/11/1974 MP 73 141 9 3,500 Shell Oil 8" oil pipeline, Segment #36 (DOI): 

Hurricane Carmen broke tie-in to 12"

pipeline, minor contacts to shoreline, brief

cleanup response in Chandeleur Area

12/18/1976 EI 297 210 17 4,000 Placid Oil 10" oil pipeline, Segment #1184 (DOI): 

trawl damage to tie-in to 14" pipeline

12/11/1981 SP 60 190 4 5,100 Atlantic 

Richfield

8" oil pipeline, Segment #4715 (DOT): 

workboat anchor damage

2/07/1988 GA A002 75 34 15,576 Amoco 

Pipeline

14" oil pipeline, Segment #4879 (DOT): 

damage from illegally anchored vessel

1/24/1990 SS 281 197 60 14,4235 Shell 

Offshore

4" condensate pipeline, Segment #8324

(DOI): anchor damage to subsea tie-in

5/06/1990 EI 314 230 78 4,569 Exxon 8" oil pipeline, Segment #4030 (DOI): trawl

damage

8/31/1992 PL 8 30 6 2,000 Texaco 20" oil pipeline, Segment #4006 (DOT): 

Hurricane Andrew, loose rig Treasure 75, 

anchor damage, minor contacts to 

shoreline, brief cleanup response

11/16/1994 SS 281 197 60 4,5335 Shell

Offshore

4" condensate pipeline, Segment #8324

(DOI): trawl damage to subsea tie-in

1/26/1998 EC 334 264 105 1,2115 Pennzoil 

E & P

16" gas & condensate pipeline, Segment

#11007 (DOT): anchor damage to tie-in to

30" pipeline, anchor dragged by vessel in

man-overboard response

9/29/1998 SP 38 108 6 8,212 Chevron 

Pipe Line

10" gas & oil pipeline, Segment #5625

(DOT): Hurricane Georges, mudslide 

damage, small amount of oil contacted

shoreline

7/23/1999 SS 241 133 50 3,200 Seashell 

Pipeline

12" oil pipeline, Segment #6462 & Segment

#6463 (DOT): “Loop Davis” jack-up rig, 

barge crushed pipeline when sat down on it

1/21/2000 SS 332 435 75 2,240 Equilon 

Pipeline

24" oil pipeline, Segment #10903 (DOT): 

anchor damage from MODU under tow
3-106 Gulf of Mexico Multisale EIS

Date

Leasing 

Area3

and 

Block 

Number

Water 

Depth 

(ft)

Distance 

to Shore 

(mi)

Volume 

Spilled 

(bbl)

Operator Pipeline Segment (pipeline authority4

) 

Cause/Consequences of Spill

9/15/2004 MC 20 479 19 1,7206 Taylor 

Energy

6" oil pipeline, Segment #7296 (DOI): 

Hurricane Ivan, mudslide damage

9/13/2008 HI A264 150 73 1,3167 HI 

Offshore 

System

42" gas pipeline, Segment #7364 (DOT): 

Hurricane Ike, anchor damage parted line

7/25/2009 SS 142 60 30 1,500 Shell Pipe 

Line

20" oil pipeline, Segment #4006 (DOT): 

micro-fractures from chronic contacts at 

pipeline crossing caused failure (separators 

between pipelines missing)

Notes: barrel (bbl) = 42 gallons, billion = 109; MODU = mobile offshore drilling unit.

Between 1964 and 2009, over 17.5 billion bbl of oil and 176.1 Mcf of natural gas were produced 

on the OCS.

1

Crude oil release unless otherwise noted; no spill contacts to land unless otherwise noted.

2

Outer Continental Shelf (OCS) – submerged lands, subsoil, and seabed administered by the U.S. 

Federal Government (http://www.boem.gov/Governing-Statutes/).

3

Gulf of Mexico leasing area unless otherwise noted (official protraction diagrams, 

http://www.boem.gov/Official-Protraction-Diagrams/l): EC = East Cameron, EI = Eugene Island, 

GA = Galveston, HI = High Island, MC = Mississippi Canyon, MP = Main Pass, PL = South Pelto, 

SS = Ship Shoal, SP = South Pass, ST = South Timbalier, and WD = West Delta.

4

Pipeline authority: DOI = Department of the Interior, Bureau of Ocean Energy Management, Regulation 

and Enforcement; DOT = Department of Transportation, Pipeline and Hazardous Materials Safety 

Administration.

5

Condensate – a liquid product of natural gas production.

6

The 1,720-bbl spill was a “passive” spill based on unrecovered pre-storm inventory trapped in the 

segment by a mudslide; no spill observed, no response required.

7

The 1,316-bbl spill was a “passive” spill based on unrecovered pre-storm inventory in the segment 

parted by storm; no spill observed, no response required.

Sources: Anderson et al., 2012; U.S. Dept. of Homeland Security, CG, 2015a.

3.2.1.3 Characteristics of OCS Oil

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 GOM. 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 oil’s chemical 

composition, including hydrocarbon groups (i.e., saturates, aromatics, resins, and 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°. 

The American Petroleum Institute gravity is a common measure of the relative density of crude oil 

and is expressed in degrees (°API) with water having a value of 10° API. Crude oils with lower 
Impact-Producing Factors and Scenario 3-107

densities and viscosities usually contain higher levels of naphtha with predominantly volatile 

paraffinic hydrocarbons (Table 3-16). Light crude oils are easier to process, while heavy crude oils 

are more difficult. The sulfur content (sweet vs. sour) of crude oil also determines the amount of 

processing required. Light sweet crude oil is preferred by refineries because of its low sulfur content 

(typically less than 0.5%) (API, 2011).

Table 3-16. 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 mg/L) Negligible

Acute Toxicity

High due to 

monoaromatic 

hydrocarbons (BTEX)

Moderate due to diaromatic 

hydrocarbons (naphthalenes 

– 2 ring PAHs)

Low, except due to smothering 

(i.e., heavier oils may sink)

Chronic Toxicity None, does not persist 

due to evaporation

PAH components (e.g., 

naphthalenes – 2 ring PAHs)

PAH components (e.g., 

phenanthrene, anthracene – 

3 ring PAHs)

Bioaccumulation 

Potential

None, does not persist 

due to evaporation Moderate Low, may bioaccumulate through sediment sorption

Compositional 

Majority

Alkanes and 

cycloalkanes

Alkanes that are readily 

degraded

Waxes, asphaltenes, and polar 

compounds (not significantly 

bioavailable or toxic)

Persistence Low due to evaporation

Alkanes readily degrade, but 

the diaromatic hydrocarbons

are more persistent

High; very low degradation 

rates and can persist in 

sediments as tarballs or asphalt 

pavements

Notes: API = American Petroleum Institute; BTEX = benzene, toluene, ethylbenzene, and xylene; 

mg/L = milligram per liter; PAH = polycyclic aromatic hydrocarbons.

Sources: Michel, 1992; Lee et al., 2015.

Data have been collected from approximately 450 deepwater EPs and DOCDs that were 

submitted to BOEM/BSEE. These data are available through BOEM’s Exploration and Development 

Plans Online Query (USDOI, BOEM, 2014b). Statistics on these API gravities show a similar range 

of 16° to 58° as those reported in the Environment Canada database. The mean value for all oils 

examined was 36°.

3.2.1.4 Transport and Fate of Offshore Spills

The physical and chemical properties of oil greatly affect its transport and fate in the 

environment. Once spilled, oil is subject to a number of physical, chemical, and biological processes 

that alter its composition and can determine environmental impacts. Horizontal transport of oil is 
3-108 Gulf of Mexico Multisale EIS

accomplished through spreading, advection, dispersion, and entrainment, whereas vertical transport 

involves dispersion, entrainment, Langmuir circulation (a series of shallow, slow, counter-rotating 

vortices at the ocean's surface aligned with the wind developed when wind blows steadily over the 

sea surface), sinking, overwashing, partitioning, and sedimentation. Following a spill, the 

composition of the released oil can change substantially due to weathering processes such as 

evaporation, emulsification, dissolution, and oxidation. The ultimate fate of oil in the environment 

and its impacts are influenced not only by the magnitude, spatial extent, and duration of the event 

but also by the response methods that may be employed (Chapter 3.2.7). More details on the 

properties and persistence of different types of oils are provided in Table 3-16.

Spreading

It is expected that some portion of spilled oil would rise and/or remain on the sea surface, 

depending on the depth of the spill and whether a subsurface plume forms. Gulf of Mexico oils, 

having an average API gravity of 36o

, have a tendency to float. Once on the sea surface, oil rapidly 

spreads out, forming a slick that is initially a few millimeters (mm) in thickness in the center and 

much thinner around the edges. The rate of spreading depends upon the viscosity of the spilled oil, 

whether or not the oil is released at the water surface or subsurface, and whether the spill is 

instantaneous or continuous for some period. The spilled oil would continue to spread until its 

thickest part is about 0.1 mm. Once it spreads thinner than 0.1 mm, the slick would begin to break 

up into small patches, forming a number of elongated slicks, with an even thinner sheen trailing 

behind each patch of oil. Oil becomes diluted as it physically mixes with the surrounding water and 

moves into the water column, and the physical mixing zone of surface oil is generally limited to 

approximately 33 ft (20 m) (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002; 

Thompson et al., 1999; Schroeder, 2000). However, under turbulent mixing conditions oil can be 

transported deeper into the water column. In one extraordinary circumstance, a tropical storm 

forced a large volume of dispersant/oil mixture as deep as 246 ft (75 m) (Silva et al., 2015).

Weathering

Immediately upon being spilled, oil begins reacting with the environment. This process is 

called weathering. A number of processes alter the chemical and physical characteristics of the 

original hydrocarbon mixture, which reduces the oil mass over time. Weathering processes include 

evaporation of volatile hydrocarbons into the atmosphere, dissolution of soluble components, 

dispersion of oil droplets into the water column, emulsification and spreading of the slick on the 

surface of the water, chemo- or photo-oxidation of specific compounds (creating new components 

that are often more soluble), and biodegradation. Weathering and the existing meteorological and 

oceanographic conditions determine the time that the oil remains on the surface of the water, and 

the characteristics of the oil at the time of contact with a particular resource also influence the 

persistence time of an oil slick. Oil-spill cleanup timing and effectiveness would also be determining 

factors. 

Chemical, physical, and biological processes operate on spilled oil to change its hydrocarbon 

compounds, reducing many of the components until the slick can no longer continue as a cohesive 
Impact-Producing Factors and Scenario 3-109

mass floating on the surface of the water. By spreading out, the oil’s more volatile components are 

exposed to the atmosphere and within a few days following a spill, light crude oils can lose up to 

75 percent of their initial volume and medium crude oils can lose up to 40 percent (NRC, 2003). 

Some crude oils mix with water to form an emulsion that is much thicker and stickier than the original 

oil (USDOC, NOAA, 2010a). Winds and waves continue to stretch and tear the oil patches into 

smaller pieces, or tarballs. Oil at a “light” API gravity would have few asphaltenes, would not 

emulsify, and would not form tarballs. Oil at a “heavy” API gravity, or enriched in heavy components 

after weathering, would more likely emulsify and form tarballs. While some tarballs may be as large 

as pancakes, most are coin-sized. Tarballs are very persistent in the marine environment and can 

travel hundreds of miles. It is expected that oil spilled as a result of an accident associated with a 

regionwide proposed action would be within the range of 30o

-35o API. BOEM used the SINTEF Oil 

Weathering Model to numerically model weathering processes to (1) estimate the likely amount of oil 

remaining on the ocean surface as a function of time and (2) predict the composition of any 

remaining oil (USDOI, MMS, 2007b). The results of BOEM’s weathering analyses were as follows. 

By 10 days after a spill event of 1,000 bbl, approximately 32-74 percent of the slick would have 

dissipated by natural weathering, with between 30 and 32 percent lost to the atmosphere via 

evaporation and between 2 and 42 percent lost into the water column via natural dispersion. The 

volume of the slick would be further reduced by spill-response efforts (Chapter 3.2.7). However, 

other fates would likely be appropriate to a catastrophic spill event, especially in deep waters. For 

example, Ryerson et al. (2011) estimated that the total hydrocarbon mass for the Deepwater Horizon

oil spill (including gas fraction) was partitioned among the following fates: ~36 percent to the deep 

subsurface plume; ~21 percent recovered by surface ships; ~10 percent to a surface slick; 

~6 percent flared at the surface; and ~4 percent evaporated at the surface, which leaves 

~23 percent unaccounted for based on available chemical data.

Persistence

The persistence of an offshore oil slick is strongly influenced by how rapidly it spreads and 

weathers and by the effectiveness of oil-spill response in removing the oil from the water surface. 

Hypothetical analyses were performed for a simulated pipeline break. Based on several scenarios 

implemented in the weathering model (e.g., variable season, oil type, and emulsification), BOEM 

estimated that the spill would dissipate from the water surface in approximately 2-10 days. Similarly, 

an OCS pipeline spill of 8,212 bbl on September 29, 1998, for which a panel investigation report was 

available, contained overflight information of the oil spill that showed the spill persisted for 5 days on 

the surface (USDOI, MMS, 1999).

Subsurface Release

The behavior of a spill depends on many factors, including the characteristics of the oil being 

spilled as well as oceanographic and meteorological conditions. Previously, an experiment in the 

North Sea indicated that the majority of oil released during a deepwater blowout would quickly rise to 

the surface and form a slick (Johansen et al., 2001). In such a case, impacts from a deepwater oil 

spill would occur at the surface where the oil is likely to be mixed into the water and dispersed by 

wind and waves. The oil would undergo natural physical, chemical, and biological degradation 
3-110 Gulf of Mexico Multisale EIS

processes including weathering. However, data and observations from the Deepwater Horizon

explosion, oil spill, and response challenged the previously prevailing thought that most oil from a 

deepwater blowout would quickly rise to the surface. Due in part to the application of subsea 

dispersants, 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 (e.g., Diercks 

et al., 2010; OSAT, 2010). Subsurface plume formation is based on numerous factors, including the 

level of subsea dispersant injection, the amount of natural dispersion related to blowout properties, 

and oceanographic conditions such as water column stratification and cross currents. After the Ixtoc

blowout in 1979, located 50 mi (80 km) offshore in the Bay of Campeche, Mexico, some subsurface 

oil also was observed dispersed within the water column (Boehm and Fiest, 1982); however, the 

scientific investigations were limited (Reible, 2010). The water quality of marine waters would be 

affected by the dissolved components and oil droplets that are small enough that they do not rise to 

the surface or are mixed down by surface turbulence. In the case of subsurface oil plumes, it is 

important to remember that these plumes would be affected by subsurface currents and could be 

diluted over time. Even in the subsurface, oil would undergo natural physical, chemical, and 

biological degradation processes including weathering.

3.2.1.5 Analysis of Offshore Spills ≥1,000 bbl

3.2.1.5.1 Overview of Spill Risk Analysis

The BOEM conducts an oil spill risk analysis prior to conducting lease sales in OCS areas 

(refer to Figure 3-12). The analysis is conducted in three parts:

(1) The trajectories of oil spills from hypothetical spill locations which are simulated 

using the OSRA Model (Smith et al., 1982).

(2) The probability of oil spill occurrence, which is based on spill rates derived from 

historical data (Anderson et al., 2012) and on estimated volumes of oil produced 

and transported.

(3) The combination of results of the first two to estimate the overall oil spill risk if 

there is oil development.

In the GOM, the Cumulative OCS Oil and Gas Program scenario comprises all future 

operations that would occur over a 70-year time period (2017-2086) from proposed, existing, and 

future leases regionwide. The analysis uses data on past OCS production and spills, along with 

estimates of future activities, to evaluate the risk of future spills.
Impact-Producing Factors and Scenario 3-111

Figure 3-12. The Oil Spill Risk Analysis Model Process.

3.2.1.5.2 Trajectory Modeling for Offshore Spills ≥1,000 bbl

The Oil Spill Risk Analysis (OSRA) model simulates the trajectory of thousands of spills 

throughout the Gulf of Mexico OCS and calculates the probability of these spills being transported 

and contacting specified geographic areas and features. Using the OSRA model, BOEM estimates 

the likely trajectories of hypothetical offshore spills ≥1,000 bbl. Only spills ≥1,000 bbl are addressed 

because smaller spills may not persist long enough to be simulated by trajectory modeling. For this 

analysis, the OSRA model was run for Alternatives A, B, and C (Tables 3-2 and 3-3) and the 

Cumulative OCS Oil and Gas Program (2017-2086).

The OSRA model uses hypothetical spill locations called launch points and simulates the 

trajectory of a spill’s movement on the surface of the water using modeled ocean currents and 

winds. The model can simulate a large number of hypothetical trajectories from each launch point. 

Spill trajectories are initiated once per day from each launch point and are time stepped every hour 

until a statistically valid number of simulations have been run to characterize the risk of contact. The 

simulated oil spills originate from approximately 6,000 points uniformly distributed 6-7 mi (10-11 km) 

apart within the Gulf of Mexico OCS. This spacing between launch points is sufficient to provide a 

resolution that creates a statistically valid characterization of the entire area (Price et al., 2001).

The model tabulates the number of times each trajectory moves across or touches a location 

(contact) occupied by polygons mapped on the gridded area. These polygons represent specified 

geographic areas and features. The OSRA model compiles the number of contacts to each feature 

that results from all of the modeled trajectory simulations from all of the launch points for a specific 

area. Contact occurs for offshore features if the trajectory simulation passes through the polygon. 
3-112 Gulf of Mexico Multisale EIS

Contact occurs for land-based features if the trajectory simulation touches the border of the feature. 

The simulation stops when the trajectory contacts the lines representing the land/water boundary or 

the borders of the domain. The probability of contact to a defined feature is calculated by dividing 

the number of contacts by the number of trajectories started at various launch locations in the 

gridded area.

The output from this component of the OSRA model provides information on the likely 

trajectory of a spill by wind and current transport, should one occur and persist for the time modeled 

in the simulations; the calculations for this EIS were modeled for 10 and 30 days. All contacts that 

occurred during these periods were tabulated for Alternatives A, B, and C (Table 3-17).

Table 3-17. Probability (percent chance) of a Particular Number of Offshore Spills 

≥1,000 Barrels Occurring as a Result of Either Facility or Pipeline 

Operations Related to Alternative A, B, or C.

Facility Spills (%) Pipeline Spills (%) Total Spills (%)

Alternative A1

Number of Spills Low High Low High Low High

1 5 21 15 37 19 36

2 <0.5 3 1 18 2 23

3 <0.5 <0.5 <0.5 6 <0.5 10

4 <0.5 <0.5 <0.5 1 <0.5 3

5 <0.5 <0.5 <0.5 <0.5 <0.5 1

Alternative B2

Number of Spills Low High Low High Low High

1 4 19 14 36 17 37

2 <0.5 2 1 16 2 20

3 <0.5 <0.5 <0.5 4 <0.5 7

4 <0.5 <0.5 <0.5 1 <0.5 2

5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Alternative C3

Number of Spills Low High Low High Low High

1 1 4 2 11 3 14

2 <0.5 <0.5 <0.5 1 <0.5 1

3 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

4 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Note: The columns under each spill category refer to the low and high resource 

estimates. Refer to Table 3-1 for more information on resource estimates.

1

Regionwide proposed lease sale.

2

Regionwide proposed lease sale excluding blocks in the WPA.

3

Regionwide proposed lease sale excluding blocks in the CPA/EPA.
Impact-Producing Factors and Scenario 3-113

3.2.1.5.3 Estimated Number of Offshore Spills ≥1,000 bbl and Probability of Occurrence

The mean number of spills ≥1,000 bbl estimated to occur as a result of each alternative is 

provided in Table 3-18. The range of the mean number of spills reflects the range of oil production 

volume estimated as a result of each alternative. The mean number of future spills ≥1,000 bbl is 

calculated by multiplying the spill rate (1.13 spills/BBO) by the volume of oil estimated to be 

produced as a result of each alternative. Spill rates were calculated based on the assumption that 

spills occur in direct proportion to the volume of oil handled and are expressed as number of spills 

per billion barrels of oil handled (spills/BBO).

Table 3-18. Mean Number and Sizes of Spills Estimated to Occur in OCS Offshore Waters from an 

Accident Related to Rig/Platform and Pipeline Activities Supporting Each Alternative Over a 

50-Year Time Period.

Spill Size Group Spill Rate

(spills/BBO)1

Number of Spills Estimated Estimated

Median Spill 

Size 

(bbl)1

Alternative A Alternative B Alternative C

0-1.0 bbl 2,020 424-2,258 374-1,959 51-290 <1

1.1-9.9 bbl 57.4 12-64 11-56 2-9 3 10.0-49.9 bbl 17.4 4-20 3-17 1-3

50.0-499.9 bbl 11.3 2-13 2-11 <1-2 126 500.0-999.9 bbl 1.63 <1-2 <1-2 <1

Platforms

>1,000-9,999 bbl 0.25 <1 <1 <1 5,066

>10,000 bbl 0.13 <1 <1 <1 –2

Pipelines

>1,000-9,999 bbl 0.88 <1-1 <1 <1 1,720

>10,000 bbl 0.18 <1 <1 <1 –2

Notes: The number of spills estimated is derived by application of the historical rate of spills 

(1996-2010) per volume of crude oil handled based on the projected production for each 

alternative (Table 3-2). The actual number of spills that may occur in the future could vary 

from the estimated number.

1

The spill rates presented are a sum of rates for United States OCS platforms/rigs and pipelines. The 

average (vs. the median) spill sizes for a larger number of spill size categories can also be found in the 

original source (Anderson et al., 2012).

2

During the last 15 years, the only ≥10,000-bbl spill was the Deepwater Horizon. However, this spill is 

considered to be a low-probability catastrophic event, which is not reasonably foreseeable and is 

therefore not included.

The probabilities for oil spill occurrence resulting from each alternative (2017-2066) and the 

Cumulative OCS Oil and Gas Program (2017-2086) for offshore spills ≥1,000 bbl can be found in 

Table 3-19 and for spills ≥10,000 bbl in Table 3-20. The OSRA model estimates the chance of oil 

spills occurring during the production and transportation of a specific volume of oil over the lifetime of 

the scenario being analyzed. The estimation process uses a spill rate constant, based on historical 

accidental spills ≥1,000 bbl, expressed as a mean number of spills per billion barrels of oil handled. 

For this analysis, the low estimate and high estimate of projected oil production for a single lease 

sale for each alternative and for the Cumulative OCS Oil and Gas Program (2017-2086) are used. 
3-114 Gulf of Mexico Multisale EIS

For more information on OCS spill-rate methodologies and trends, refer to Anderson et al. (2012). A 

discussion of how the range of resource estimates was developed is provided in Chapter 3.1.1 and 

Table 3-1.

Table 3-19. Oil-Spill Occurrence Probability Estimates for Offshore Spills ≥1,000 Barrels Resulting from 

Each Alternative (2017-2066) and the Cumulative OCS Oil and Gas Program (2017-2086).

Forecasted Oil 

Production 

(Bbbl)1

Mean Number of Spills Estimated to Occur Estimates of Probability (% chance) 

of One or More Spills

Platforms Pipelines Tankers Total Platforms Pipelines Tankers Total

Single Lease Sale Alternatives

Alternative A2 0.210 0.05 0.19 0 0.24 5 17 <0.5 21

1.118 0.28 0.98 0.01 1.27 24 63 <0.5 72

Alternative B3 0.185 0.05 0.16 0 0.21 5 15 <0.5 19

0.970 0.24 0.85 0 1.10 22 57 <0.5 67

Alternative C4 0.026 0.01 0.02 0 0.03 1 2 <0.5 3

0.148 0.04 0.13 0 0.17 4 12 <0.5 15

Cumulative OCS Oil and Gas Program

Regionwide 15.482 3.87 13.62 0.08 17.57 98 >99.5 7 >99.5

25.806 6.45 22.71 0.13 29.29 >99.5 >99.5 12 >99.5

CPA/EPA 13.590 3.40 11.96 0.07 15.42 97 >99.5 7 >99.5

22.381 5.60 19.70 0.11 25.40 >99.5 >99.5 11 >99.5

WPA 1.892 0.47 1.66 0 2.14 38 81 <0.5 88

3.425 0.86 3.01 0 3.87 58 95 <0.5 98

Notes: Bbbl = billion barrels.

“Platforms” refers to facilities used in exploration, development, or production. 1

Values represent the low and high resource estimates. Refer to Table 3-1 for more information on resource estimates. 2

Regionwide proposed lease sale.

3

Regionwide proposed lease sale excluding blocks in the WPA. 4

Regionwide proposed lease sale excluding blocks in the CPA/EPA.

Source: Ji, official communication, 2015.

Table 3-20. Oil-Spill Occurrence Probability Estimates for Offshore Spills ≥10,000 Barrels Resulting from 

Each Alternative (2017-2066) and the Cumulative OCS Oil and Gas Program (2017-2086).

Forecasted Oil 

Production 

(Bbbl)1

Mean Number of Spills Estimated to Occur Estimates of Probability (% chance)

of One or More Spills

Platforms Pipelines Tankers Total Platforms Pipelines Tankers Total

Single Sale Alternatives

Alternative A2 0.210 0.03 0.04 0 0.07 3 4 <0.5 6

1.118 0.15 0.20 0 0.35 14 18 <0.5 29

Alternative B3 0.185 0.02 0.03 0 0.06 2 3 <0.5 6

0.970 0.13 0.17 0 0.30 12 13 <0.5 26

Alternative C4 0.026 0 0 0 0.01 <0.5 <0.5 <0.5 1

0.148 0.02 0.03 0 0.05 2 3 <0.5 4

Cumulative OCS Oil and Gas Program

Regionwide 15.482 2.01 2.79 0.02 4.82 87 94 2 99

25.806 3.35 4.65 0.04 8.04 97 99 4 >99.5

CPA/EPA 13.590 1.77 2.45 0.02 4.23 83 91 2 99

22.381 2.91 4.03 0.04 6.97 95 98 4 >99.5
Impact-Producing Factors and Scenario 3-115

Forecasted Oil 

Production 

(Bbbl)1

Mean Number of Spills Estimated to Occur Estimates of Probability (% chance)

of One or More Spills

Platforms Pipelines Tankers Total Platforms Pipelines Tankers Total

WPA 1.892 0.25 0.34 0 0.59 22 29 <0.5 44

3.425 0.45 0.62 0 1.06 36 46 <0.5 65

Notes: Bbbl = billion barrels.

“Platforms” refers to facilities used in exploration, development, or production. 1

Values represent the low and high resource estimates. Refer to Table 3-1 for more information on resource estimates. 2

Regionwide proposed lease sale.

3

Regionwide proposed lease sale excluding blocks in the WPA.

4

Regionwide proposed lease sale excluding blocks in the CPA/EPA.

Source: Ji, official communication, 2015.

3.2.1.5.4 Most Likely Source of Offshore Spills ≥1,000 bbl

Table 3-17indicates the probabilities of one or more spills ≥1,000 bbl occurring from OCS 

facility or pipeline operations related to each alternative. The most likely cause of a spill ≥1,000 bbl 

is a pipeline break at the seafloor (Anderson et al., 2012). The various circumstances responsible 

for pipeline breaks included during the 1996-2010 analysis period were damage by an anchor, 

mudslide damage during a hurricane, a jack-up rig barge crushing the pipeline when it sat down on

it, and microfractures from chronic contacts at a pipeline crossing where separators between the 

pipelines were missing.

3.2.1.5.5 Most Likely Size of an Offshore Spill ≥1,000 bbl

The estimated size of an offshore spill utilizes the median spill size from the trend analysis 

found in Anderson et al. (2012) for accidents occurring from drilling rig, platform, or pipeline 

activities. Extreme events such as the Deepwater Horizon oil spill skew the average and, as such, 

does not provide a useful statistical measure. The median size of spills ≥1,000 bbl that occurred 

during 1996-2010 is 2,240 bbl. This size was calculated based on the nine spills (both platforms/rigs 

and pipelines) that occurred during this timeframe and included the Deepwater Horizon oil spill. For 

information on the mean number and size of spills estimated to occur for each alternative, refer to 

Table 3-18. 

3.2.1.5.6 Length of Coastline Affected by Offshore Spills ≥1,000 bbl

The BOEM has previously estimated the length of shoreline that could be contacted if a spill 

≥1,000 bbl occurred as a result of an accident associated with each alternative (USDOI, MMS, 

2007b). The length of shoreline contacted is dependent upon the original spill size and the volume 

of oil removed by natural weathering and offshore cleanup operations prior to the slick making 

shoreline contact. The shoreline length contacted is a simple arithmetic calculation based on the 

area of the remaining slick. The calculation assumes that the slick will be carried 30 m (98 ft) 

inshore of the shoreline, either onto the beachfront up from the water’s edge or into the bays and 

estuaries, and will be spread out at uniform thickness of 1 mm; this assumes that no oil-spill boom is 

used. The maximum length of shoreline affected by a spill of 4,600 bbl was estimated to be 

30-50 km (19-31 mi) of shoreline, assuming such a spill were to reach land within 12 hours. Some 
3-116 Gulf of Mexico Multisale EIS

redistribution of the oil due to longshore currents and further smearing of the slick from its original 

landfall could also occur.

3.2.1.5.7 Risk Analysis by Resource

The BOEM analyzes risk to resources from oil spills and oil slicks that could occur as a result 

of each alternative. The results are based on BOEM’s estimates of likely spill locations, sources, 

sizes, frequency of occurrence, the physical fate of different types of oil slicks, and the probable 

transport that are described in more detail in the preceding spill scenarios. For offshore spills, 

combined probabilities were calculated using the OSRA model, which includes both the likelihood of 

a spill from each alternative occurring and the likelihood of the oil slick reaching areas where known 

resources exist.

The environmental, social and economic resources utilizing the OSRA modeling results were 

selected by BOEM analysts. Details on the individual resource categories, as well as a detailed 

analysis of the impacts to each resource from oil spills, are provided under each resource category 

in Chapter 4. 

3.2.1.5.8 Likelihood of an Offshore Spill ≥1,000 bbl Occurring and Contacting Coastal and 

Offshore Areas

A more complete measure of spill risk was calculated by multiplying the probability of contact 

generated by the OSRA model by the probability of occurrence of one or more spills 1,000 bbl as a 

result of each alternative. This provides a risk factor that represents the probability of a spill 

occurring as a result of each alternative and contacting a specified geographic area or feature. 

These are referred to as “combined probabilities” because they combine the risk of occurrence of a 

spill from OCS sources and the risk of such a spill contacting areas of sensitive environmental, 

social and economic resources. The combined probabilities for an offshore spill ≥1,000 bbl 

occurring and contacting coastal and offshore areas for each for each alternative can be found in the 

figures in Appendix E. 

To better reflect the geologic distribution of oil and gas resources and natural variances of 

meteorological and oceanographic conditions in the computation of combined probabilities, BOEM 

also generated combined probabilities for smaller areas within the GOM. A cluster analysis was 

used to analyze the contact probabilities generated for each of the 6,000 launch points. For this 

analysis, similar trajectories and contact to 10-mi (16-km) shoreline segments were tabulated to 

identify offshore cluster areas. The estimated oil production from each alternative was proportionally 

distributed to the cluster areas and the likelihood of spill occurrence was calculated for each cluster 

area. The probability of spill occurrence was combined with probabilities of contact from the 

trajectory modeling to estimate the combined risk of spills occurring and contacting specific areas 

from spills in each cluster area. To account for the risk of spills occurring from the transportation of 

oil to shore, generalized pipeline corridors originating within each of the offshore cluster areas and 

terminating at major oil pipeline landfall areas were developed. The oil volume estimated to be 

produced as a result of each alternative within each cluster area was proportioned among the 
Impact-Producing Factors and Scenario 3-117

pipeline corridors. The mean number of spills and the probability of contact of spills from each 

pipeline corridor were then calculated and combined with the risk of spills occurring and contacting 

resources from OCS facility development and production operations to complete the analysis.

3.2.1.6 Analysis of Offshore Spills <1,000 bbl

3.2.1.6.1 Estimated Number of Offshore Spills <1,000 bbl and Total Volume of Oil Spilled

The number of spills <1,000 bbl estimated to occur over the next 50 years as a result of each 

alternative is provided in Table 3-18. The number of spills is estimated by multiplying the oil-spill 

rate for each of the different spill size groups by the projected oil production as a result of each 

alternative (Tables 3-2 and 3-3). As spill size increases, the occurrence rate decreases and so the 

number of spills estimated to occur decreases.

3.2.1.6.2 Most Likely Source and Type of Offshore Spills <1,000 bbl

Most spills <1,000 bbl on the OCS would likely occur from a mishap on a production facility, 

most likely related to a failure related to the storage of oil. From 1995 to 2009, there were 

14,191 spills <1,000 bbl on platforms, rigs, or vessels and 1,139 spills from pipelines (Anderson 

et al., 2012). Spills on platforms and rigs could be crude or refined (diesel, hydraulic) oil. Reported 

pipeline spills are likely to be crude oil, and vessel spills are likely to be refined oil. For spills 

<1,000 bbl, a total of 19,050 bbl were released to OCS waters from platforms, rigs, or vessels, and 

8,002 bbl were released from pipelines.

3.2.1.6.3 Most Likely Size of Offshore Spills <1,000 bbl

Table 3-11 provides the most likely volume of oil estimated to be spilled for each of the spillsize groups. As stated previously, the estimated size of an offshore spill utilizes the median spill size 

from the trend analysis in Anderson et al. (2012) for all spill-size classes During the 50-year analysis 

period, 96 percent of all spills estimated to occur as a result of each alternative would be small spills 

<1 bbl (Anderson et al., 2012).

3.2.1.6.4 Likelihood of an Offshore Spill <1,000 bbl Occurring and Contacting Coastal and 

Offshore Areas

Because spills <1,000 bbl are not expected to persist as a slick on the surface of the water 

beyond a few days and because spills on the OCS would occur at least 3-10 nmi (3.5-11.5 mi; 

5.6-18.5 km) from shore, it is unlikely that any spills would make landfall prior to breaking up. For an 

offshore spill <1,000 bbl to make landfall, the spill would have to occur proximate to State waters 

(defined as 3-12 mi [5‐19 km] from shore). If a spill were to occur proximate to State waters, only a 

spill >50 bbl would be expected to have a chance of persisting long enough to reach land. Spills 

>50 and <1,000 bbl are infrequent. Should such a spill occur, the volume that would make landfall 

would be expected to be extremely small (a few barrels).
3-118 Gulf of Mexico Multisale EIS

3.2.1.7 Analysis of Coastal Spills

Coastal spills occur in coastal waters, which are defined here as State offshore waters and 

spills in navigation channels, rivers, and bays from barges and pipelines carrying OCS-produced oil. 

These spills occur at shoreline storage, processing, and transport facilities supporting the OCS oil 

and gas industry. BOEM projects that most (>90%) oil produced as a result of a proposed action 

under Alternative A would be brought ashore via pipelines to oil pipeline shore bases, stored at 

these facilities, and eventually transferred via pipeline or barge to GOM 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.

3.2.1.7.1 Estimated Number and Most Likely Sizes of Coastal Spills

According to the USCG database for the most recent 12 years, January 2002-April 2014, 

(USDHS, USCG, 2015a) (Table 3-13), in the waters 0-3 nmi (0-3.45 mi; 5.56 km) off the Texas 

coast, there were a total of 93 spills reported from 2002 to 2014 or about 15 spills <1,000 bbl/yr. In 

the waters 0-3 nmi (0-3.45 mi; 5.56 km) off the Louisiana coast, there were a total of more than 

1,493 spills reported from 2002-2014, or about 124 spills <1,000 bbl/yr. In the waters 0-3 mi 

(0-5 km) off the Mississippi coast, there were a total of 4 spills reported from all sources, or about 

0.3 spills <1,000 bbl/yr. In the waters 0-3 nmi (0-3.45 mi; 5.56 km) off the Alabama coast, there 

were a total 15 spills reported from all sources from 1996 to 2009, or about 1.3 spills <1,000 bbl/yr. 

In the waters 0-3 nmi (0-3.45 mi; 5.56 km) off the Florida coast, there were a total 5 spills reported 

from all sources from 2002-2014, or about 0.4 spills <1,000 bbl/yr. When limited to just oil- and gasrelated spill sources such as platforms, pipelines, MODU’s, and support vessels, 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 energy-related commercial and recreational 

activities remain the same. The coastal waters of Louisiana, Texas, Mississippi, Alabama, and 

Florida have had a total of 124, 15, 0.3, 1.3, and 0.4 spills <1,000 bbl/yr, respectively. Assuming 

future trends would reflect past historical records, it is also predicted that Louisiana will be the state 

most likely to have a spill ≥1,000 bbl occur in water 0-3 mi (0-5 km) offshore.

3.2.1.7.2 Likelihood of Coastal Spill Contact

Estimates of future coastal spills are based on historical spills reported to the USCG. Based 

upon historical data, offshore Louisiana is the most likely location for the occurrence of a coastal 

spill. A spill that occurs in Federal waters could also be transported to State waters.

3.2.2 Losses of Well Control

All losses of well control are required to be reported to BSEE. In 2006, BOEM and BSEE’s 

predecessor (the Minerals Management Service), revised the regulations for loss of well control 

incident reporting, which were further clarified in NTL 2010-N05, “Increased Safety Measures for 

Energy Development on the OCS.” Operators are required to document any loss of well control 
Impact-Producing Factors and Scenario 3-119

event, even if temporary, and the cause of the event by mail or email to the addressee indicated in 

the NTL. The operator does not have to include kicks that were controlled but should include the 

release of fluids through a flow diverter (a conduit used to direct fluid flowing from a well away from 

the drilling rig). The current definition for loss of well control is as follows:

• uncontrolled flow of formation or other fluids (the flow may be to an exposed 

formation [an underground blowout] or at the surface [a surface blowout]);

• uncontrolled flow through a diverter; and/or

• uncontrolled flow resulting from a failure of surface equipment or procedures.

Not all loss of well control events would result in a blowout as defined above, but it is most 

commonly thought of as a release to the human environment. A loss of well control can occur during 

any phase of development, i.e., exploratory drilling, development drilling, well completion, 

production, or workover operations. A loss of well control can occur when improperly balanced well 

pressure results in sudden, uncontrolled releases of fluids from a wellhead or wellbore (PCCI Marine 

and Environmental Engineering, 1999; Neal Adams Firefighters, Inc., 1991). Of the 47 loss of well 

control events reported in the GOM from 2007 to 2014, 25 (53%) resulted in loss of fluids at the 

surface or underground (USDOI, BSEE, 2015b).

The BSEE reports that they have had 288 unique loss of well control incidents captured in 

their database from 1956 to 2010 (Herbst, 2014), with an additional 22 incidents documented from 

2010 through August 2015. A synopsis conducted by BSEE of the 288 well incidents that occurred 

from 1956 through 2010 shows the following:

• 69 of the 288 incidents had duration greater than or equal to 5 days (24%); 

• 55 of the 69 incidents occurred in water depths <300 ft (91 m) (80%);

• 42 of the 69 incidents occurred within 50 mi (80 km) of shore (61%);

• a total of 31 fatalities occurred in 5 of the 69 incidents;

• a total of 84 injuries occurred in 7 of the 69 incidents; and

• 8 of the 69 incidents were oil blowouts (12%).

In contrast, the Deepwater Horizon oil spill continued uncontained for 87 days, between 

April 20 and July 15, 2010. The Deepwater Horizon blowout in Mississippi Canyon Block 252 

resulted in the release of 4.9 MMbbl of oil and large quantities of gas (McNutt et al., 2011). For 

purposes of calculating the maximum possible civil penalty under the CWA, a January 2015 

judgement used a quantity of 4.0 million barrels of oil for total discharged and 3.19 million barrels of 

oil as the actual amount that was released into environment (Barbier and Shushan 2015). As shown 

by the Deepwater Horizon explosion and oil spill, the loss of well control in deep water presents 

obstacles and challenges that differ from a loss of well control in shallow waters. Although many of 
3-120 Gulf of Mexico Multisale EIS

the same techniques used for wild well control efforts in shallow water were used to attempt to 

control the Macondo well, these well control efforts were hindered by water depth, which required 

reliance solely upon the use of ROVs for all well intervention efforts. This is a concern in deep water 

because the inability to quickly regain control of a well increases the size of a spill.

There are several options that can be attempted to control a well blowout. Common kill 

techniques include (1) bridging, (2) capping/shut-in, (3) capping/diverting, (4) surface stinger, 

(5) vertical intervention, (6) offset kill, and (7) relief wells (Neal Adams Firefighters, Inc. 1991). 

Although much has been learned about well control as a result of the Deepwater Horizon explosion, 

oil spill, and response, if a deepwater subsea blowout occurs in the future, it is still likely that an 

operator would be required to immediately begin to drill one or more relief wells to gain control of the 

well. This may be required whether or not this is the first choice for well control because a relief well 

is typically considered the ultimate final solution for regaining well control in such circumstances. 

Although it can take months, the actual amount of time required to drill the relief well depends upon 

the following: (1) the depth of the formation below the mudline; (2) the complexity of the 

intervention; (3) the location of a suitable rig; (4) the type of operation that must be terminated in 

order to release the rig (e.g., may need to complete a casing program before releasing the rig); and 

(5) any problems mobilizing personnel and equipment to the location.

The major difference between a blowout during the drilling phase versus the completion or 

workover phases is the tendency for a drilling well to “bridge off.” Bridging is a phenomenon that 

occurs when severe pressure differentials are imposed at the well/reservoir interface and the 

formation around the wellbore collapses and seals the well. Deepwater reservoirs are susceptible to 

collapse under “high draw down” conditions. However, a completed well may not have the same 

tendency to passively bridge off as would a drilling well involving an uncased hole. Bridging would 

have a beneficial effect for spill control by slowing or stopping the flow of oil from the well (PCCI 

Marine and Environmental Engineering, 1999). There is a difference of opinion among blowout 

specialists regarding the likelihood of deepwater wells bridging naturally in a short period of time. 

Completed wells, or those in production, have more severe consequences in the event of a blowout 

due to the hole being fully cased down to the producing formation, which lowers the probability of 

bridging (PCCI Marine and Environmental Engineering, 1999). Therefore, the potential for a well to 

bridge is greatly influenced by the phase of a well. Refer to Chapter 3.2.7 for a discussion of 

planned well-source containment options that were designed to address an ongoing loss of well 

control event.

Blowout Preventers

A blowout preventer (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 can cut 

through or pinch shut well casing and sever tool strings. The BOPs were invented in the early 

1920’s and have been instrumental in ending dangerous, costly, and environmentally damaging oil 

gushers on land and in water. The BOPs have been required for OCS oil and gas operations from 

the time offshore drilling began in the late 1940’s. 
Impact-Producing Factors and Scenario 3-121

The BOPs are actuated as a last resort upon imminent threat to the integrity of the well or the 

surface rig. For cased wells, in a normal situation, the hydraulic ram may be closed if oil or gas from 

an underground zone enters the wellbore and destabilizes it. 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.

Because BOPs are important for the safety of the drilling crew, as well as the rig and the 

wellbore itself, BOPs are regularly inspected, tested, and refurbished. The post-Deepwater Horizon

explosion, oil spill, and response regulations and inspection program required for BOPs is discussed 

in Appendix A.5. Among the changes are new provisions for BOP testing. In addition, the 

Technology Assessment Program, a research element within BOEM’s regulatory program, supports 

research associated with operational safety and pollution prevention. Since the Deepwater Horizon

explosion, oil spill, and response, several well control-related studies have been funded through this 

program and the details of this research can be found on BSEE’s website at 

http://www.bsee.gov/Technology-and-Research/Technology-Assessment-Programs/index/.

3.2.3 Accidental Air Emissions

Accidental events associated with offshore oil and gas activities can result in the emission of 

air pollutants. These OCS oil- and gas-related accidental events could include the release of oil, 

condensate, or natural gas; chemicals used offshore; pollutants from the burning of these products; 

fire; or H2S release. The air pollutants could include NAAQS criteria pollutants, volatile and semivolatile organic compounds, hydrogen sulfide, and methane. Emissions sources related to accidents 

from OCS operations can include well blowouts, oil spills, pipeline breaks, tanker accidents, and 

tanker explosions.

If a fire was associated with an accidental event, it could produce a broad array of pollutants 

including VOCs, NAAQS primary pollutants, and greenhouse gases. Although temporary in nature, 

response activities could impact air quality. These response activities could include in-situ burning, 

the use of flares to burn gas and oil, and the use of dispersants applied from aircraft. In-situ burning 

could impact air quality due to the possible release of toxic gases, and dispersants could impact air 

quality by possibly releasing toxic aromatics into the atmosphere. Atmospheric pollutants emitted 

from the Deepwater Horizon oil spill included plumes of organic aerosol particles and VOCs. In 

these plumes, the highly volatile species evaporated on time scales of <10 hours, while intermediate 

volatility evaporated between 10 and 1,000 hours. After the highly volatile species surfaced, they 

spread to a larger area due to surface currents and contributed to a wide spectrum of vapors 

(Bahreini et al., 2012). Additionally, in the presence of evaporating hydrocarbons from the oil spill, 

NOx emissions from the recovery and cleanup activities produced ozone (Middlebrook et al., 2012).

The presence of H2S within formation fluids occurs sporadically in the Gulf of Mexico OCS

and may be released during an accident. Accidents involving the release of H2S could result in 

irritation, injury, and lethality from leaks; exposure to sulfur oxides produced by flaring; equipment 
3-122 Gulf of Mexico Multisale EIS

and pipeline corrosion; and outgassing and volatilization from spilled oil. Regulations and NTLs 

include safeguards and protective measures, which are in place to protect workers from H2S 

releases.

3.2.3.1 Hydrogen Sulfide and Sulfurous Petroleum

Sulfur may be present in oil as elemental sulfur, within gas as H2S, or within organic 

molecules, all three of which vary in concentration independently. Safety and infrastructure 

concerns include the following: irritation, injury, and even lethality to workers who are exposed to 

H2S from leaks; exposure to sulfur oxides produced by flaring; equipment and pipeline corrosion; 

and outgassing and volatilization from spilled oil.

Sour oil and gas occur sporadically throughout the Gulf of Mexico OCS, primarily off the 

Louisiana, Mississippi, and Alabama coasts. Sour hydrocarbon tends to originate in carbonate 

source or reservoir rocks that may not have abundant clay minerals that serve as a binder for 

elemental sulfur. If not bound in clay minerals, it remains free and can become a part of any 

hydrocarbon produced or sourced from that rock.

Deep gas reservoirs on the GOM continental shelf are likely to have high corrosive content, 

including H2S. There is some evidence that petroleum from deepwater areas may be sulfurous, but 

exploration wells have not identified deepwater areas that are extraordinarily high in H2S 

concentration.

BOEM reviews all exploration and development plans in the Gulf of Mexico OCS for the 

possible presence of H2S in the area(s) identified for exploration and development activities. 

Activities determined to be associated with a presence of H2S are subjected to further review and 

requirements. Federal regulations at 30 CFR § 250.490(c) require all lessees, prior to beginning 

exploration or development operations, to request a classification of the potential for encountering 

H2S. The classification is based on previous drilling and production experience in the areas 

surrounding the proposed operations, as well as other factors.

According to BSEE’s regulations at 30 CFR § 250.490(f), all operators on the OCS involved 

in production of sour gas or oil (i.e., >20 ppm) are also required to file an H2S Contingency Plan. 

This plan lays out procedures to ensure the safety of the workers on the production facility. In 

addition, all operators are required under 30 CFR § 250.107 to adhere to the National Association of 

Corrosion Engineers’ (NACE) Standard Material Requirements—Methods for Sulfide Stress 

Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments (NACE MR0175-

2003) (NACE, 2003) as best available and safest technology. The NACE standards that relate to an 

H2S partial pressure of 0.05 pounds per square inch absolute primarily address stress cracking and 

stress corrosion resistance, while BSEE’s definition of “H2S present” addresses human safety and 

protecting the environment for H2S concentrations equal to or exceeding 20 ppm. The BSEE is 

concerned if either threshold is crossed (NTL 2009-G31). These engineering standards preserve 

the integrity of infrastructure through specifying equipment to be constructed of materials with 
Impact-Producing Factors and Scenario 3-123

metallurgical properties that resist or prevent sulfide stress cracking and stress corrosion cracking in 

the presence of sour gas. The BSEE issued a final rule (30 CFR § 250.490; Federal Register, 1997) 

governing requirements for preventing H2S releases, detecting and monitoring H2S and sulfur 

dioxide, protecting personnel, providing warning systems and signage, and establishing 

requirements for H2S flaring and venting. The NTL 2009-G31 establishes Standard Material 

Requirements, Materials for Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in 

Sour Oilfield Environments (NACE Standard MR0175-2003) as best available and safest technology, 

provides further guidance on classifying an area for the presence of H2S, includes guidance on H2S 

detection, updates regulatory citations, and includes a guidance document statement. Hydrogen 

sulfide contingency plans are discussed in Appendix A.8. 

3.2.4 Pipeline Failures

Significant sources of damages to OCS pipeline infrastructure can be caused by corrosion 

(Chapters 3.1.4.1 and 3.1.6.1), physical pipeline stress due to location, mass sediment movements 

and mudslides that can exhume or push the pipelines into another location, and accidents due to 

weather or impacts from anchor drops or boat collisions.

Long unsupported pipelines subjected to strong bottom currents will experience vortexinduced vibrations, which significantly increase pipeline fatigue. Two potential causes for pipeline 

failure are regional-scale hydrodynamic forces and vortex-induced vibrations. Hydrodynamic forces 

are of most concern to pipelines with multiple unsupported spans. In conjunction with strong 

episodic events, these pipelines may experience lateral instability and movement. Although the

effects of hydrodynamic forces warrant attention, vortex-induced vibrations are perhaps of greatest 

concern.

Following the 2004, 2005, and 2008 hurricane seasons, BOEM commissioned studies to 

examine the failure mechanisms of offshore pipelines (Atkins et al., 2007; Energo Engineering, 

2010; Atkins et al., 2006). Numerous pipelines were damaged after the 2004-2008 hurricanes 

passing through the CPA and WPA. Much of the reported damage was riser or platform-associated 

damage, which typically occurs when a platform is toppled or otherwise damaged. While many 

pipelines were damaged, few resulted in a spill >50 bbl. The total pipeline damage reports and 

number of spills are listed by hurricane below.

Hurricane Total Pipeline 

Damage Reports

Number of Spills 

>50 bbl

Ivan 168 8

Katrina 299 5

Rita 243 5

Gustav and Ike 314 6

The largest spills are typically due to pipeline movements, mudslides, anchor drops, and 

collisions of one type or another. Most pipeline damage occurs in shallow water (<200 ft; 61 m) 

because of the potential for increasing impacts of the storm on the seabed in shallow water, the 
3-124 Gulf of Mexico Multisale EIS

relative density of pipelines, or the age and design standards of the pipeline or the platforms to 

which the pipelines are connected. The future impact of hurricanes on damage to pipelines is 

uncertain. As oil production shifts from shallow to deeper water, there may be a consolidation of 

pipeline utilization.

The uncertain location of pipelines is an ongoing safety and environmental hazard. On 

October 23, 1996, in Tiger Pass, a channel through the Mississippi River Delta into the Gulf of 

Mexico near Venice, Louisiana, the crew of the Bean Horizon Corporation dredge Dave Blackburn 

dropped a stern spud (a large steel shaft that is dropped into the river bottom to serve as an anchor 

and a pivot during dredging operations) into the bottom of the channel in preparation for continued 

dredging operations. The spud struck and ruptured a 12-in (30-cm) diameter, submerged natural 

gas steel pipeline. Within seconds of reaching the surface, the natural gas ignited, destroying the 

dredge and the tug (USDOT, National Transportation Safety Board, 1998). Lack of awareness of 

the precise location of the pipeline was a major contributing factor to this accident (USDOT, National 

Transportation Safety Board, 1998). On December 5, 2003, this Agency received an incident report 

that a cutterhead dredge barge ruptured a 20-in (51-cm) diameter condensate pipeline in Eugene 

Island Block 39. Lack of awareness of the precise location of the pipeline was the major contributing 

factor to this accident as well. An OCS-related spill ≥1,000 bbl would likely be from a pipeline 

accident; the median spill size is estimated to be 2,200 bbl for rig/platform and pipeline activities 

supporting each alternative (Table 3-14). For Alternative A, B, or C, up to one spill of this size is 

estimated to occur.

3.2.5 Vessel and Helicopter Collisions

BOEM’s data show that, from 2007 to 2014, there were 137 OCS oil- and gas-related 

collisions (USDOI, BSEE, 2015c). Most collision mishaps are the result of service vessels colliding 

with platforms or vessel collisions with pipeline risers. Approximately 10 percent of vessel collisions 

with platforms in the OCS caused diesel spills. Fires resulted from hydrocarbon releases in several 

of the collision incidents. To date, the largest diesel spill associated with a collision occurred in 1979 

when an anchor-handling boat collided with a drilling platform in the Main Pass leasing area, spilling 

approximately 1,500 bbl. In 2014, an approximated 3,571 bbl of bunker fuel spilled into the Houston 

Ship Channel after a collision between a barge and a ship. Diesel fuel is the product most frequently 

spilled, while oil, natural gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been released 

as the result of a vessel collision. Human error accounts for approximately half of all reported vessel 

collisions from 2006 to 2010. Safety fairways, traffic separation schemes, and anchorages are the 

most effective means of preventing vessel collisions with OCS structures. In general, fixed 

structures such as platforms and drilling rigs are prohibited in fairways. Temporary underwater 

obstacles, such as anchors and attendant cables or chains attached to floating or semisubmersible 

drilling rigs, may be placed in a fairway under certain conditions. A limited number of fixed 

structures may be placed at designated anchorages. The USCG’s requirements for indicating the 

location of fixed structures on nautical charts and for lights, sound-producing devices, and radar 

reflectors to mark fixed structures and moored objects also help minimize the risk of collisions. To 

prevent any further incidents in regard to collisions with submerged or destroyed platforms following 
Impact-Producing Factors and Scenario 3-125

Hurricanes Katrina and Rita, in December 2005, the Bureau of Ocean Energy Management, 

Regulation and Enforcement published a safety alert that provided the location of all facilities that 

were destroyed during the storms. In addition, the USCG 8th District’s Local Notice to Mariners 

(monthly editions and weekly supplements) informs GOM users about the addition or removal of 

drilling rigs and platforms, locations of aids to navigation, and defense operations involving 

temporary moorings. Marked platforms often become aids to navigation for vessels (particularly 

fishing boats and vessels supporting offshore oil and gas operations) that operate in areas with high 

densities of fixed structures.

The National Offshore Safety Advisory Committee (NOSAC, 1999) examined collision 

avoidance measures between a generic deepwater structure and marine vessels in the GOM. The 

NOSAC offered three sets of recommendations: (1) voluntary initiatives for offshore operators; 

(2) joint government/industry cooperation or study; and (3) new or continued USCG action. The 

NOSAC (1999) proposes that oil and gas facilities be used as aids-to-navigation because of their 

proximity to fairways, fixed nature, well-lighted decks, and inclusion on navigational charts. Mariners 

intentionally set and maintain course toward these facilities, essentially maintaining a collision 

course. Unfortunately, most deepwater facilities do not install collision avoidance radar systems to 

alert offshore facility personnel of a potentially dangerous situation. The NOSAC estimates that 

7,300 large vessels (tankers, freight ships, passenger ships, and military vessels) pass within 35 mi 

(56 km) of a typical deepwater facility each year. This estimate resulted in approximately 20 transits 

per day for the 13 deepwater production structures existing in 1999. The NOSAC found the total 

collision frequency to be approximately one collision per 250 facility-years (3.6 x 10-3 per year). The

NOSAC estimated that, if the number of deepwater facilities increases to 25, the estimated total 

collision frequency would increase to one collision in 10 years. A cost-benefit analysis within the 

report did not support the use of a dedicated standby vessel for the generic facility; however, the 

analysis did support the use of a radar system on deepwater facilities if the annual costs of the 

system were less than or equal to $124,500.

The OCS oil- and gas-related vessels could collide with marine mammals, sea turtles, and 

other marine animals during transit. To limit or prevent such collisions, the NMFS provides all boat 

operators with whale-watching guidelines, which is derived from the Marine Mammal Protection Act. 

These guidelines suggest safe navigational practices based on speed and distance limitations when 

encountering marine mammals. The frequency of vessel collisions with marine mammals, sea 

turtles, or other marine animals probably varies as a function of spatial and temporal distribution 

patterns of the living resources, as the pathways of maritime traffic (coastal traffic is more 

predictable than offshore traffic), and as a function of vessel speed, the number of vessel trips, and 

the navigational visibility.

The average number of helicopter accidents per year in the GOM since 1984 has been 

7.9 per year, with the last 10 years averaging 4.7 per year and with only two in 2014. The 2014 

GOM oil industry helicopter accident rate per 100,000 flight hours was 0.68, with a total of two 

accidents compared with a 31-year annual average accident rate of 1.74. The fatal accident rate per 
3-126 Gulf of Mexico Multisale EIS

100,000 flight hours during 2014 was 0.34 compared with a 31-year average of 0.44 (Heliport Safety 

Advisory Conference, 2015).

Since 1999, there have been 23 accidents of which only 5 were fatal; this resulted in 

13 fatalities and 15 injuries. The leading causes, not all inclusive, of the accidents since 1999 were 

engine related, loss of control or improper procedures, helideck obstacle strikes, controlled flight into 

terrain, and other technical failures (Helicopter Safety Advisory Conference, 2015).

3.2.6 Chemical and Drilling-Fluid Spills

Chemicals and synthetic-based drilling fluids are used in offshore oil and gas drilling and 

production activities, and may be spilled to the environment due to equipment failure, weather (i.e., 

wind, waves, and lightning), accidental collision, and human error.

Chemicals are stored and used to condition drill muds during production and in well 

completions, stimulation, and workover procedures. The relative quantity of their use is reflected in 

the largest volumes spilled. Well completion, workover, and treatment fluids, including calcium 

chloride brine and zinc bromide, are the largest quantity used and are typically the largest accidental

releases. Zinc bromide is of particular concern because it is persistent (nondegradable) and is 

comparatively toxic. 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). Other common chemicals spilled include methanol and 

ethylene glycol, which are used in deepwater operations where gas hydrates tend to form due to 

cold temperatures. These alcohol-based chemicals are nonpersistent (degradable) and exhibit 

comparatively low toxicity.

The SBF has typically been used since the mid-1990s for the deeper well sections because 

SBF has superior performance properties. The synthetic oil used in SBF is relatively nontoxic to the 

marine environment and has the potential to biodegrade. However, SBF is considered more toxic 

than water-based fluid, and spills of SBF are categorized separately from water-based fluid releases. 

Accidental riser disconnections result in the release of large quantities of drilling fluid.

Refer to Table 3-21 for information on spill statistics for chemicals and SBFs for 2007-2012 

(USDOI, BSEE, 2015d). The BSEE reports spills in categories of 10-49 bbl (small spills) and 

>50 bbl (large spills). Table 3-21 shows the total annual spill volumes in barrels of product lost for 

SBFs and chemicals in both spill size categories. The number of spill incidents per year are listed 

with the average spill volume in barrels for a given year.
Impact-Producing Factors and Scenario 3-127

Table 3-21. Number and Volume of Chemical and Synthetic-Based Fluid Spills for 

10-49 Barrels and >50 Barrels in the Gulf of Mexico from 2007 through 2014.

Year

Product Lost 

(bbl) Number of Spills Average Spill Volume (bbl)

SBF Chemical SBF Chemical SBF Chemical

A. Spills 10-49 bbl

2007 110 17 6 1 18 17

2008 73 102 2 6 37 17

2009 38 24 1 2 38 12

2010 54 51 3 3 18 17

2011 73 0 2 0 37 0 

2012 88 12 4 1 22 12

2013 51 20 2 1 26 20

2014 0 0 0 0 0 0

Average 

Value 61 28 3 2 24 12

B. Spills Greater Than 50 bbl

Year Product Lost (bbl) Number of Spills Average Spill Volume 

(bbl)

SBF Chemical SBF Chemical SBF Chemical

2007 1,518 550 2 1 759 550

2008 1,849 3,229 2 16 925 202

2009 602 500 4 3 151 167

2010 131 123 2 1 66 123

2011 252 0 2 0 126 0 

2012 158 1,595 3 5 53 319

2013 0 0 0 0 0 0 

2014 323 66 3 1 108 66

Average 

Value 604 758 2 3 273 178

SBF = synthetic-based fluid.

During the period of 2007 to 2014, small SBF spills occurred at an average annual volume of 

61 bbl, while large spills occurred at an annual average volume of 601 bbl. During the same period, 

small chemical spills occurred at an average annual volume of 28 bbl, while large chemical spills 

occurred at an average annual volume of 758 bbl. Small SBF spills averaged 24 bbl per spill, while 

large SBF spills averaged 178 bbl per spill. A spike in the volume of large chemical spills in 2008 is 

attributed to Hurricane Ike, which occurred on September 13, 2008.
3-128 Gulf of Mexico Multisale EIS

3.2.7 Spill Response

3.2.7.1 BSEE Spill-Response Requirements and Initiatives

3.2.7.1.1 Spill-Response Requirements

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, BSEE was tasked with a 

number of oil-spill response duties and planning requirements. Within BSEE, the Oil Spill 

Preparedness Division addresses all aspects of offshore oil-spill planning, preparedness, and 

response. Additional information about the Oil Spill Preparedness Division can be found on BSEE’s 

website at http://www.bsee.gov/About-BSEE/Divisions/OSPD/index/. 

The BSEE implements the following regulations according to 30 CFR parts 250 and 254:

• requires immediate notification for spills >1 bbl—all spills require notification to 

USCG, and BSEE receives notification from the USCG of all spills ≥1 bbl;

• conducts investigations to determine the cause of a spill;

• assesses civil and criminal penalties, if needed;

• oversees spill source control and abatement operations by industry;

• sets requirements and reviews and approves OSRPs for offshore facilities (More 

information on oil-spill response plan regulations and processes can be found in 

Appendix A.5.);

• 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 receives and reviews the worst-case discharge information submitted for EPs, DPPs, 

and DOCDs on the OCS. BOEM also has regulatory requirements addressing site-specific OSRPs 

and spill-response information. As required by BOEM at 30 CFR §§ 550.219 and 550.250, 

operators are required to provide BOEM with an OSRP that is prepared in accordance with 30 CFR 

part 254 subpart B with their proposed exploration, development, or production 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:
Impact-Producing Factors and Scenario 3-129

• a discussion of the approved regional 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 in accordance with 30 CFR § 

254.26(a) and a comparison of the worst-case discharge in the approved 

regional OSRP with the worst-case discharge calculated for the proposed 

activities; and

• a description of the worst-case discharge response scenario 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)-(e).

All OSRPs are reviewed and approved by BSEE, whether submitted with a BOEMassociated 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. 

BOEM’s regulations require that an operator must have an approved OSRP prior to BOEM’s 

approval of an operator-submitted exploration, development, or production plan.

The operator is also required to carry out the training, equipment testing, and periodic drills 

described in the OSRP. In addition, since 1989, BSEE has conducted government-initiated 

unannounced exercises. In any given year, BSEE will hold both table-top, unannounced exercises 

and a limited number of response equipment deployment unannounced exercises. Equipment 

deployment exercises are held when BSEE elects to conduct an exercise of an operator’s 

procurement, loading, and deployment of certain pieces of oil-spill response equipment that are cited 

within an operator’s OSRP. The BSEE equipment deployment exercises are designed most often to 

take place in open water in waterways adjacent to where the equipment is stored in order to test the 

equipment that is proposed to be utilized offshore during the response, but the exercise may be 

moved to an alternate location if BSEE’s exercise parameters require it. In addition, BSEE can also 

require that the nearshore and onshore equipment be deployed if a BSEE-developed drill scenario 

requires it. Drills testing the nearshore and onshore equipment would typically take place in an 

onshore or nearshore environment within the vicinity of a staging or storage area.

Any dispersant application included as part of the drill scenario always simulates the actual 

application of dispersant during BSEE’s drills. No actual dispersants are ever utilized during the 

drills. Likewise, the oil spill itself is only simulated during any of BSEE’s unannounced drills. Typical 

BSEE unannounced deployment exercises last only a few hours and rarely take longer than a day. 

Multi-day scenarios only occur when a more complicated drill scenario is developed by BSEE to test 

an operator’s ability to adequately respond. Several NTLs and guidance documents have been 

issued by BOEM and BSEE that clarify oil-spill requirements since the occurrence of the Deepwater 
3-130 Gulf of Mexico Multisale EIS

Horizon explosion, oil spill, and response. More information on these NTLs and guidance 

documents can be found in Appendix A.5. 

3.2.7.1.2 Spill-Response Initiatives

For more than 25 years, BSEE and its predecessors have maintained a comprehensive longterm research program to improve oil-spill response knowledge and technologies. The major focus 

of the program is to improve the methods and technologies used for oil-spill detection, containment, 

treatment, recovery, and cleanup. The BSEE Oil Spill Response Research program is a cooperative 

effort bringing together funding and expertise from research partners in State and Federal 

government agencies, industry, academia, and the international community. The funded projects 

cover numerous spill-response-related issues such as chemical treating agents; in-situ burning of oil; 

research conducted at BSEE’s Oil Spill Response Test Facility (Ohmsett) located in Leonardo, New 

Jersey; behavior of oil; decisionmaking support tools; mechanical containment; and remote sensing.

The BSEE’s recently awarded research contracts that highlight the varied types of research 

projects can be found on BSEE’s website at http://www.bsee.gov/Technology-and-Research/OilSpill-Response-Research/index/. 

3.2.7.2 Offshore Response, Containment, and Cleanup Technology

In the event of a spill, particularly a loss of well control, there is no single method of 

containment and removal that would be 100 percent effective. Spill cleanup is a complex and 

evolving technology. There are many situations and environmental conditions that necessitate 

different approaches. New technologies constantly evolve, but they provide only incremental 

benefits. Each new tool then becomes part of the spill-response tool kit. Each spill-response 

technique/tool has its specific uses and benefits (Fingas, 1995). Offshore removal and spillcontainment efforts to respond to an ongoing spill offshore would likely require multiple technologies, 

including source containment, mechanical spill containment and cleanup, in-situ burning of the slick, 

and the use of 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 can be contained and removed offshore.

Because no single spill-response method is 100 percent effective, it is likely that larger spills 

under the right conditions would require the simultaneous use of all available cleanup methods (i.e., 

source containment, mechanical spill containment and cleanup, dispersant application, and in-situ

burning). Accordingly, the response to the Deepwater Horizon explosion, oil spill, and response

employed all of these options simultaneously. The cleanup technique chosen for a spill response 

would vary depending upon the unique aspects of each situation. The selected mix of 

countermeasures would depend upon the shoreline and natural resources that may be impacted; the 

size, location, and type of oil spilled; weather; and other variables. The overall objective of on-water 

recovery is to minimize the risk of impact by preventing the spread of free-floating oil. The physical 

and chemical properties of crude oil can greatly affect the effectiveness of containment and recovery 

equipment, dispersant application, and in-situ burning. It is expected that oil found in the majority of 
Impact-Producing Factors and Scenario 3-131

the proposed lease sale area could range from medium weight oil to condensate. The variety of 

standard cleanup protocols that were used for removing Deepwater Horizon oil from beaches, 

shorelines, and offshore water are identified in Table 3-22. 

Table 3-22. Primary Cleanup Options Used during the Deepwater Horizon Response.

Fresh Oil Sheens Mousse Tarballs Burn Residue

On-Water 

Response

Disperse, skim, 

burn

Light sheens very 

difficult to recover, 

heavier sheens 

picked up with 

sorbent boom or 

sorbent pads

Skim Snare boom Manual removal

On-Land 

Response

Sorbent pads, 

manual recovery, 

flushing with water, 

possible use of 

chemical shoreline 

cleaning agents

Light sheens very 

difficult to recover, 

heavier sheens 

picked up with 

sorbent boom or 

sorbent pads

Sorbent 

pads, manual 

recovery

Snare boom, 

manual 

removal, beach 

cleaning 

machinery

Manual removal

Source: USDOC, NOAA, 2010a.

Most oil-spill response strategies and equipment are based upon the simple principle that oil 

floats. However, as evident during the Deepwater Horizon explosion, oil spill, and response, this is 

not always true. Sometimes it floats and sometimes it suspends within the water column or sinks to 

the seafloor (refer to Chapter 3.2.1.4). Oil suspended in the water column and moving with the 

currents is difficult to track and recover using standard visual survey methods (Coastal Response 

Research Center, 2007).

Source Containment 

The NTL 2010-N10 states 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 BSEE does 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).

Marine Well Containment Company

The Marine Well Containment Company’s (MWCC’s) Containment System includes two 

modular capture vessels (MCVs); enhanced subsea umbilical, risers, and flowlines (SURF) 
3-132 Gulf of Mexico Multisale EIS

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 by providing 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 Gulf of Mexico, defined as water depths from 500 to 10,000 ft (1,524-3,048 m), in 

temperatures up to 350 °F (177 °C), and under pressure up to 15,000 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. It is envisioned that this system 

could be fully operational within days to weeks after a spill event occurs (Marine Spill Response 

Corporation, 2015a).

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, to operate 

and maintain the system (Marine Spill Response Corporation, 2015a). The MWCC would provide 

fully trained crews to operate the system, ensure the equipment is operational and ready for rapid 

response, and conduct research on new containment technologies (Marine Spill Response 

Corporation, 2015a).

In the summer of 2012, a full-scale deployment of MWCC’s critical well-control equipment to 

exercise the oil and gas industry’s response to a potential subsea blowout in the deep water 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 explosion, 

oil spill, and was continually working in the Gulf of Mexico. Helix Well Ops’ system, which is referred 

to as the Helix Fast Response System today, 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 
Impact-Producing Factors and Scenario 3-133

integrity to be shut-in. The Helix Fast Response System 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 Well Containment 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 deep water 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.

3.2.7.2.1 Mechanical Cleanup

Generally, mechanical containment and recovery is the primary oil-spill response method 

used (33 CFR § 153.305(a)). Mechanical recovery is the process of using booms and skimmers to 

pick up oil from the water surface. Booms are used to enclose oil and prevent it from spreading; to 

protect harbors, bays, and biologically sensitive areas; to divert oil to areas where it can be 

recovered or treated; and to concentrate oil and maintain an even thickness so that skimmers can be 

used; or other cleanup techniques, such as in-situ burning, can be applied. Sorbent booms are 

specialized containment and recovery devices made of porous sorbent material such as woven or 

fabric polypropylene, which absorbs oil while it is being contained. Sorbent booms are used when 

the oil slick is relatively thin for final polishing of an oil spill, to remove small traces of oil or sheen, or 

as a backup to other booms. Skimmers are mechanical devices designed to remove oil from the 

water surface. Skimmers are classified according to their basic operating principles: oleophilic 

surface skimmers; weir skimmers; suction skimmers or vacuum devices; elevating skimmers; and 

submersion skimmers (Fingas, 2013).

It is expected that the oil-spill response equipment needed to respond to an offshore spill in 

the proposed 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, New Iberia, 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, 2015b; 

National Response Corporation, 2015). Response times for any of this equipment would vary, 

depending on the location of the equipment, the staging area, and the spill site; and on the transport 

requirements for the type of equipment procured. It is anticipated that equipment would be procured 

from the closest available oil-spill equipment bases.

As indicated in Chapter 3.2.7.1 and Appendix A.5, BSEE oversees a research program to 

improve the capabilities for detecting and responding to an oil spill in the marine environment. One 
3-134 Gulf of Mexico Multisale EIS

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 is currently utilizing the results 

of this study during their review and approval of operator-submitted OSRPs (USDOI, BSEE, 2015b). 

The USCG has indicated that the guidance generated by this research is applicable for offshore use 

but that a separate standard would still need to be developed for nearshore response capability 

determinations.

If an oil spill occurs during a storm, spill response from shore may be delayed to after the 

storm. Spill response would not be possible while storm conditions continued, given the sea-state 

limitations for skimming vessels and containment boom deployment. However, oil released onto the 

ocean surface during a storm event would be subject to accelerated rates of weathering and 

dissolution (i.e., oil and water would be agitated, forcing oil into smaller droplets and facilitating 

dissolution of the high end aromatic compounds present).

In rough seas, a large spill of low viscosity oil, such as a light or medium crude oil, can be 

scattered over many square kilometers within just a few hours. Oil recovery systems typically have 

swath widths of only a few meters and move at slow speeds while recovering oil. Therefore, even if 

this equipment can become operational within a few hours, it would not be feasible for them to 

encounter more than a fraction of a widely spread slick (International Tanker Owners Pollution 

Federation Limited, 2010). For this reason, it is assumed that a maximum of 10-30 percent of an oil 

spill in an offshore environment can be mechanically removed from the water prior to the spill

making landfall (U.S. Congress, Office of Technology Assessment, 1990). Some newer oil 

skimming equipment procured internationally displayed faster recovery speed during the response to 

the Deepwater Horizon oil spill, and some changes were also made in the logistics of how skimmers 

and booms were positioned offshore during this response that increased the equipment’s swath 

width. However, for the Deepwater Horizon response, it was estimated that only 3 percent of the 

total oil spilled was picked up by mechanical equipment offshore (Lubchenco et al., 2010).

A common difficulty when deploying booms and skimmers to recover oil is coordinating 

vessel activities to work the thickest areas of oil (International Tanker Owners Pollution Federation 

Limited, 2010). It is a rule of thumb that 90 percent of the oil is in 10 percent of the area. The 

10 percent of the oil that makes up 90 percent of a slick is typically sheen. For this reason, 

containment and recovery operations on water require extensive logistical support to direct the 

response effort. Additionally, the limitations that poor weather and rough seas impose on spillresponse operations offshore are seldom fully appreciated. Handling wet, oily, slippery equipment 

on vessels that are pitching and rolling is difficult and can raise safety considerations. Winds, wave 

action, and currents can drastically reduce the ability of a boom to contain and a skimmer to recover 
Impact-Producing Factors and Scenario 3-135

oil. It is important to select equipment for a response that is suitable for the type of oil and the 

prevailing weather and sea conditions for a region. Efforts should generally be made to target the 

heaviest oil concentrations and areas where collection and removal of the oil would reduce the 

likelihood of oil reaching sensitive resources and shorelines. As oil weathers and increases in 

viscosity, cleanup techniques and equipment should be reevaluated and modified (International 

Tanker Owners Pollution Federation Limited, 2010).

Practical limitations of strength, water drag, and weight mean that generally only relatively 

short lengths of boom (tens to a few hundred meters) can be deployed and maintained in a working 

configuration. Towing booms at sea (e.g., in U or J configurations, which increase a skimmer’s 

swath width) is a difficult task requiring specialized vessels and trained personnel (International 

Tanker Owners Pollution Federation Limited, 2010). Additional boom limitations are discussed in 

Chapter 3.2.7.3. Because skimmers float on the water surface, they experience many of the 

operational difficulties that apply to booms, particularly those posed by wind, waves, and currents 

(International Tanker Owners Pollution Federation Limited, 2010). The effectiveness of any skimmer 

depends upon a number of factors, in addition to the ambient weather and sea conditions, including 

the type of oil, the thickness of the oil, the presence of debris in the oil or in the water, the extent of 

weathering and emulsification of the oil, and the location of the spill (Fingas, 2013). Even moderate 

wave motion can greatly reduce the effectiveness of most skimmer designs (International Tanker 

Owners Pollution Federation Limited, 2010). In high sea-state conditions, many skimmers, 

especially weir and suction skimmers, take up more water than oil (Fingas, 2013). Because of the 

various constraints placed upon skimmers in the field, their design capacities are rarely realized. 

Experience from numerous spills has consistently shown that skimmer recovery rates reported under 

test conditions cannot be sustained during a spill response (International Tanker Owners Pollution 

Federation Limited, 2010). The availability of sufficient oil-storage facilities is necessary to ensure 

continuous oil-spill recovery. This storage needs to be easy to handle and easy to empty once full 

so that it can be used repeatedly with the least interruption in recovery activity (International Tanker 

Owners Pollution Federation Limited, 2010).

There are no proven methods for the containment of submerged oil, and methods for 

recovery of submerged oils have limited effectiveness. Efforts to mechanically contain and/or 

recover suspended oil have focused on different types of nets, either the ad hoc use of fishing nets 

or specially designed trawl nets. There has been some research conducted on the design of trawl 

nets for the recovery of emulsified fuels. However, the overall effectiveness for large spills is 

expected to be very low. The suspended oil can occur as liquid droplets or semisolid masses in 

sizes ranging from millimeters to meters in diameter (Coastal Response Research Center, 2007). At 

spills where oil has been suspended in the water column, responders have devised low technology 

methods for tracking the presence and spread of oil over space and time. For suspended oil, these 

methods include stationary systems such as snare sentinels, which can consist of any combination 

of the following: a single length of white absorbent pom-poms (snare) on a rope attached to a float 

and an anchor; one or more crab traps on the bottom that are stuffed with snare; and minnow or 

other type of traps that are stuffed with snare and deployed at various water depths. The 

configuration would depend upon the water depth where the oil is located within the water column. 
3-136 Gulf of Mexico Multisale EIS

At present, it is not possible to determine the particle size, number of particles, or percent oil cover in 

the water column based upon the visual observations of oil on these systems (Coastal Response 

Research Center, 2007).

Spills involving submerged oil trigger the need for real-time data on current profiles (surface 

to bottom), wave energy, suspended sediment concentrations, detailed bathymetry, seafloor 

sediment characteristics, and sediment transport patterns and rates. These data are needed to 

validate or calibrate models (both computer and conceptual), direct sampling efforts, and predict the 

behavior and fate of the submerged oil. This information might be obtained through the use of 

acoustic Doppler current profilers, dye tracer studies, rapid seafloor mapping systems, and 

underwater camera or video systems that can record episodic events (Coastal Response Research 

Center, 2007). During the Deepwater Horizon response, fluorimeters were used successfully to 

detect the presence of submerged oil.

3.2.7.2.2 Spill Treating Agents

Treating oil with specially prepared chemicals is another option for responding to oil spills. 

An assortment of chemical spill treating agents is available to assist in cleaning up oil. However, 

approval must be obtained in accordance with the provisions of the National Oil and Hazardous 

Substances Pollution Contingency Plan (NCP) before these chemical agents can be used.

The USEPA has recently issued a proposed rule to amend the requirements in Subpart J of 

the 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 

proposed rule addresses the efficacy, toxicity, environmental monitoring of dispersants, and other 

chemical and biological agents, as well as public, State, local 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 following types of products that are authorized 

for use on oil discharges:

• dispersants; 

• surface washing agents;

• surface collecting agents;

• bioremediation agents; and

• miscellaneous oil-spill control agents.

In February 2014, the USEPA also 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, 2014b).
Impact-Producing Factors and Scenario 3-137

Dispersants

When dispersants are applied to spilled crude oil, the surface tension of the oil is reduced, 

allowing wind and wave action to break the oil into tiny droplets that are dispersed into the upper 

portion of the water column. Oil that is chemically dispersed at the surface move into the top 20 ft 

(6 m) of the water column where it mixes with surrounding waters and begins to biodegrade (U.S. 

Congress, Office of Technology Assessment, 1990). Dispersant use, in combination with natural 

processes, breaks up oil into smaller components that allows them to dissipate into the water and 

degrade more rapidly (Nalco, 2010). Dispersant use must be in accordance with a Regional 

Response Team’s (RRT) Preapproved Dispersant Use Manual and with any conditions outlined 

within a RRT’s site-specific, dispersant approval given after a spill event. Consequently, dispersant 

use must be in accordance with the restrictions for specific water depths, distances from shore, and 

monitoring requirements. At this time, neither the Region IV nor the Region VI RRT dispersant use 

manuals, which cover the GOM region, give preapproval for the application of dispersant use 

subsea. However, the USEPA is presently revisiting these RRT preapprovals in light of the 

dispersant issues, such as subsea application, that arose during the Deepwater Horizon response. 

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 Coordinator.

In addition, this letter indicated that more robust documentation may be required. This 

documentation would include daily reports that contain the products used, specific time and locations 

of application, equipment used for each application, spotter aircraft reports, photographs, vessel 

data, and analytical data.

Additionally, in light of the dispersant issues that arose during the Deepwater Horizon

response, the State of Florida’s Department of Environmental Protection submitted a letter dated 

May 5, 2011, to the USEPA Region IV RRT in which the State of Florida withdrew all State waters 

(9 nmi [10.36 mi; 16.67 km] off the coast of Florida in the Gulf of Mexico) from the Green Zone (or 

approved area) for dispersant preapproval as outlined within the Use of Dispersants in Region IV 

document (USEPA, Region IV Regional Response Team, 1996). The State indicated in the letter 

that this change was requested due to the enormous changes that have occurred in communication 

and response technologies since the preapproval was first agreed to in 1996. The State indicated 

that they felt that the Use of Dispersants in Region IV document needed to be updated to reflect 
3-138 Gulf of Mexico Multisale EIS

technological advances and lessons learned during the response to the Deepwater Horizon oil spill 

(State of Florida, Dept. of Environmental Protection, 2011).

For a deepwater (>1,000-ft [305-m] water depth) spill ≥1,000 bbl, dispersant application may 

be a preferred response in the open-water environment to prevent oil from reaching a coastal area, 

in addition to mechanical response. However, the window of opportunity for successful dispersant 

application may be somewhat narrower for some deepwater locations that are dependent upon the 

physical and chemical properties of oil, which tend to be somewhat heavier than those found closer 

to shore. A significant reduction in the window of opportunity for dispersant application may render 

this response option ineffective.

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 (i.e., 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 water depths 

below 300 m (984 ft) and below the pycnocline or in the interface between an upper mixed density 

gradients and a lower stable density gradient. The surface application guidance supplements and 

complements the existing protocols as outlined within the existing Special Monitoring of Applied 

Response Technologies 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 Special Monitoring of Applied Response Technologies 

protocols and to ensure that their planning and response activities are consistent with national 

policy.

The most popular application method for dispersants in the offshore GOM is from small and 

large fixed-wing aircraft. Based on the present location of dispersant stockpiles and dispersant 

application equipment available to the Oil Spill Removal Organizations used by offshore operators in 

the GOM, it is expected that the dispersant application aircraft called out for an oil-spill response to 

an offshore spill in the proposed lease sale area would come from Houma, Louisiana; Kiln, 

Mississippi; Mesa, Arizona; Concord, California; and/or Salisbury, Maryland. Stockpiles of 

dispersants are located at each of the designated staging airports. Response times for this 

equipment would vary, depending on the spill site and on the transport time for additional supplies of 

dispersants to arrive at a staging location. Based on historic information, this Multisale EIS assumes 

that dispersant application applied to the water surface would be effective on 20-50 percent 

(S.L. Ross Environmental Research Ltd., 2000) of the treated oil.

If an oil spill occurs during a storm, the dispersant application would occur following the 

storm. Aerial and vessel dispersant application would not be possible while storm conditions 

continued. However, oil released onto the ocean surface during a storm event would be subject to 
Impact-Producing Factors and Scenario 3-139

accelerated rates of weathering and dissolution (i.e., oil and water would be agitated, forcing oil into 

smaller droplets and facilitating dissolution of the high-end aromatic compounds present).

Other Spill Treating Agents

Surface washing agents, emulsion breakers and inhibitors, recovery enhancers, solidifiers, 

and sinking agents are other types of chemical treatment agents that are available, if approval is 

obtained, for treating oil spills. The use of these chemical products is subject to approval in the 

same manner as dispersants. The use of bioremediation agents also requires approval in the same 

manner as dispersants. The U.S. Environmental Protection Agency’s NCP Product Schedule 

Notebook 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, 2014b).

3.2.7.2.3 In-situ Burning

In-situ burning is an oil-spill cleanup technique that involves the controlled burning of the oil 

at or near a spill site. The use of this spill-response technique can provide the potential for the 

removal of large amounts of oil over an extensive area in less time than other techniques. In ideal 

circumstances, in-situ burning requires less equipment and much less labor than other cleanup 

techniques (Fingas, 2013). In-situ burning involves the same oil collection process used in 

mechanical recovery, except instead of going into a skimmer, the oil is funneled into a fire boom, 

which is a specialized boom that has been constructed to withstand the high temperatures from 

burning oil. While in-situ burning is another method for disposing of oil that has been collected in a 

boom, this method is typically more effective than skimmers when the oil is highly concentrated. Insitu burning was successfully used in 411 burns during the Deepwater Horizon oil-spill response, 

successfully eliminating between 220,000 and 300,000 bbl of oil from the water surface (Allen, 

2010), approximately 5 percent of the Macondo oil spilled (Lubchenco et al., 2010).

Because of the successful use of this technology during the Deepwater Horizon oil-spill 

response, the Gulf of Mexico’s Oil Spill Removal Organizations have procured fire boom, which they 

have strategically stockpiled throughout the GOM region. Response times for bringing a fireresistant boom onsite would vary, depending on the location of the equipment, the staging area, and 

the spill site. If an oil spill occurs during a storm, in-situ burning would occur following the storm. 

In-situ burning would not be possible while storm conditions continued.

3.2.7.2.4 Natural Dispersion

Depending upon environmental conditions and spill size, the best response to a spill may be 

to allow the natural dispersion of a slick to occur. Natural dispersion may be a preferred option for 

smaller spills of lighter nonpersistent oils and condensates that form slicks that are too thin to be 

removed by conventional methods and that are expected to dissipate rapidly, particularly if there are 

no identified potential impacts to offshore resources and a potential for shoreline impact is not 
3-140 Gulf of Mexico Multisale EIS

indicated. In addition, natural dispersion may also be a preferred option in some nearshore 

environments, such as a marsh habitat, when the potential damage caused by a cleanup effort could 

cause more damage than the spill itself. For more information on the transport and fate of oil spills, 

refer to Chapter 3.2.1.3. 

3.2.7.3 Onshore Response and Cleanup

Offshore response and cleanup is preferable to shoreline cleanup; however, if an oil slick 

reaches the coastline, it is expected that the specific shoreline cleanup countermeasures identified 

and prioritized in the appropriate Area Contingency Plans (ACPs) for various habitat types would be 

used. The sensitivity of the contaminated shoreline is the most important factor in the development 

of cleanup recommendations. Shorelines of low productivity and biomass can withstand more 

intrusive cleanup methods such as pressure washing. Shorelines of high productivity and biomass 

are very sensitive to intrusive cleanup methods and, in many cases, the cleanup is more damaging 

than allowing natural recovery.

Oil-spill response planning in the U.S. is accomplished through a mandated set of 

interrelated plans. The 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, providing detailed information on response procedures, priorities, 

and appropriate countermeasures. The USCG has worked diligently to improve coastal oil-spill 

response since the Deepwater Horizon oil spill by improving the ACPs for each coastal USCG 

sector. The GOM coastal area that falls within the USCG’s 8th District is covered by ACPs for areas 

covered by USCG Sector Corpus Christi, Sector Houston/Galveston, Sector Port Arthur, Sector 

Morgan City, Sector New Orleans, and Sector Mobile. The ACPs from the USCG’s 7th District cover 

the remaining GOM coastal area. The Gulf of Mexico OCS Region’s ACPs also include separate 

Geographic Response Plans (GRP), which are developed jointly with local, State, and other Federal 

entities to better focus spill-response tactics and priorities. These GRPs contain the resources 

initially identified for protection during a spill, response priorities, procedures, and appropriate spillresponse countermeasures. The ACPs are written and maintained by Area Committees assembled 

from Federal, State, and local government agencies that have pollution-response authority; 

nongovernmental participants may attend meetings and provide input. The coastal Area 

Committees are chaired by respective Federal On-Scene Coordinators from the appropriate USCG 

Office and are comprised of members from local or area-specific jurisdictions. Response 

procedures identified within an ACP or its GRP(s) reflect the priorities and procedures agreed to by 

members of the Area Committees.

If an oil slick reaches the coastline, the responsible party should be prepared to deploy any 

of the shoreline cleanup countermeasures that were specified for the protection of the prioritized 

sensitive areas that are identified within the appropriate GRPs that cover these areas. The single, 

most-frequently recommended, spill-response strategy for the areas identified for protection in all of 

the applicable ACPs or its GRPs is the use of a shoreline boom to deflect oil away from coastal 

resources such as seagrass beds, marinas, resting areas for migratory birds, bird and turtle nesting 
Impact-Producing Factors and Scenario 3-141

areas, etc. Since oil spilled at sea tends to move and spread rapidly into very thin layers, boom is 

deployed to corral the oil on the water to enhance recovery effectiveness of skimmers and other 

response technologies. Boom is also used to protect shoreline areas and to minimize the 

consequences of an oil spill reaching shore. There are tradeoffs in deciding where and when to 

place boom because, once deployed, boom is time consuming to tend and to relocate. For example, 

booming operations are sensitive to wind, wave, and currents and need to be tethered and secured 

to keep the boom from moving. Rough seas can tear, capsize, or shred boom. Currents over 

1.5 knots (1.7 miles per hour) or even a wake from a boat can send oil over or under a boom. 

Untended boom can become a barricade to wildlife and ship traffic. Boom anchors can damage 

some habitats. During the Deepwater Horizon response, it was discovered that hard boom often did 

more damage in the marsh it was intended to protect than anticipated after weather conditions 

ended up stranding the boom back into the marsh.

If a shoreline is oiled, the selection of the type of shoreline remediation to be used would 

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, 

decision-makers must assess the severity and nature of the injury using Shoreline Cleanup and 

Assessment Team (SCAT) survey observations. These onsite decisionmakers must also estimate 

the time it would 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) (U.S. 

National Response Team, 2010). The variety of standard cleanup protocols that were used for 

removing Macondo oil from beaches, shorelines, and offshore water are identified in Table 3-22. 

During the Deepwater Horizon shoreline response, oiling conditions generally included 

surface and buried oil layers, surface and buried oil/sand balls, stained sand, and sunken oil in the 

adjacent subtidal waters. Since waste minimization was a core principle considered when cleaning 

sand beaches, efforts were made to remove as little sediment as practical from the shore zone 

during cleaning operations. Treatment methods for sand beaches comprised manual and 

mechanical removal, an on-site treatment plant, and sediment relocation. Mechanical removal 

involved a range of commercial self-propelled or towed machines designed primarily to sieve debris 

and litter on recreational beaches. Field trials were conducted to evaluate which specific 

mechanisms were more appropriate for the different oiling conditions. The beach cleaners were 

used as scrapers on the more heavily oiled beaches in Louisiana, whereas the sieving function was 

more appropriate to recover oil particles on the beaches of Mississippi, Alabama, and Florida. Oiled 

wetlands included Spartina salt marshes and Phragmites (“roseau cane”) brackish-freshwater 

wetlands in the Mississippi Delta. Because previous spills in this region provided an understanding 

of the recovery potential for the oiled wetlands, natural recovery was the preferred strategy in most 

cases based on the generally light oiling conditions. Natural attenuation was relatively rapid if an 

area was only lightly oiled, as the Macondo well oil type had an API gravity of 35 ̊. A guiding 

principle for wetland treatment was to minimize physical intrusion and work from floating platforms, 
3-142 Gulf of Mexico Multisale EIS

skiffs, or shallow-draft barges, whenever possible. Floating mechanical flushing machines, using 

concrete pump arms, were used on a limited scale to reach into oiled fringe wetlands to wash and 

recover mobile oil. Oiled rip rap, breakwaters, and groins and jetties were treated through manual 

removal of bulk oil and were washed using a range of temperatures and pressures depending on the 

character of the oil (Owens et al., 2011).

Shoreline Cleanup Countermeasures

When spilled oil contaminates shoreline habitats, responders should survey the affected 

areas to determine appropriate response. Although general approvals or decision tools for using 

shoreline cleanup methods can be developed during pre-spill planning stages, responders’ specific 

treatment recommendations should integrate gathered, filed, and documented data on shoreline

habitats, oil type, the degree of shoreline contamination, spill-specific physical processes, and 

ecological and cultural resource issues. Cleanup endpoints should be established early so that 

appropriate cleanup methods can be selected to meet the cleanup objectives. Shoreline surveys, as 

part of the SCAT program, should be conducted systematically because they are imperative to the 

cleanup decisions. Also, repeated surveys are needed to monitor the effectiveness of the ongoing 

treatment methods so that the need for changes in methodology, additional treatment, or constraints 

can be evaluated (USDOC, NOAA, 2013a).

The following assumptions and guidance regarding the cleanup of spills that contact coastal 

resources are identified in NOAA’s Characteristic Coastal Habitats: Choosing Spill Response 

Alternatives job aid, which provides general guidance adopted in the Gulf of Mexico OCS Region’s 

ACPs (USDOC, NOAA, 2010b). The ACPs applicable to the GOM coastal region encompass a vast 

geographical area. The differences in the response priorities and procedures among the various 

ACPs or the GRPs reflect the differences in the identified resources needing spill protection.

Sand Beaches

Predicted Oil Behavior

Light oil accumulations would be deposited as oily swashes or bands along the upper 

intertidal zone of sand beaches. Heavy oil accumulations would cover the entire beach surface. Oil 

would be lifted off of the lower beach with the rising tide. The maximum penetration of oil into fineto-medium-grained sand is about 10-15 cm (4-6 in) and up to 25 cm (10 in) in coarse-grained sand. 

Burial of oiled layers by clean sand can be rapid (within 1 day), and burial to depths as much as 1 m 

(3 ft) is possible if the oil comes ashore at the beginning of a depositional period. Organisms living 

in the beach sediment may be killed by smothering or lethal oil concentrations in the interstitial 

water. Biological impacts include temporary declines in infauna, which can affect important 

shorebird foraging areas.

Response Considerations

Sand beaches are one of the easiest shoreline types to clean. Cleanup would concentrate 

on removing oil and oily debris from the upper swash zone once most of the oil has come ashore. 
Impact-Producing Factors and Scenario 3-143

Manual cleanup, rather than road graders and front end loaders, is advised to minimize the volume 

of sand removed from the shore and requiring disposal. All efforts should focus on preventing 

vehicular and foot traffic from mixing oil deeper into the sediments. Mechanical reworking of lightly 

oiled sediments from the high-tide line to the middle intertidal zone can be effective along exposed 

beaches.

Salt to Brackish Marshes

Predicted Oil Behavior

Oil adheres readily to intertidal vegetation in salt and brackish marshes. The band of coating 

would vary widely depending upon the water level at the time of oiling. Large slicks would persist 

through multiple tidal cycles and will coat the entire stem from the high-tide line to the base. Heavy 

oil coating would be restricted to the outer fringe of thick vegetation, although lighter oils can 

penetrate deeper, to the limit of tidal influence. Medium to heavy oils do not readily adhere to or 

penetrate the fine sediments but can pool on the surface or in animal burrows and root cavities. 

Light oils can penetrate the top few centimeters of sediment and, under some circumstances, oil can 

penetrate burrows and cracks up to 1 m (3 ft).

Response Considerations

Under light oiling, the best practice is to let the area recover naturally. Natural removal 

processes and rates should be evaluated before conducting cleanup. Heavily pooled oil can be 

removed by vacuum, sorbents, or low-pressure flushing. During flushing, care should be taken to 

prevent transporting oil to sensitive areas down slope or along shore. Cleanup activities should be 

carefully supervised to avoid damaging vegetation. Any cleanup activity should not mix the oil 

deeper into the sediments, trampling of the plants and disturbance of soft sediments should be 

minimized. Lastly, aggressive cleanup methods should only be considered when other resources 

(e.g., migratory birds and endangered species) are at greater risk from oiled vegetation left in place.

Sand and Gravel Beaches

Predicted Oil Behavior

During small spills, oil could be deposited along and above the high-tide swash on sand and 

gravel beaches. Large spills would likely spread across the entire intertidal area. Oil penetration 

into the beach sediments may be up to 50 cm (20 in); however, the sand fraction can be quite mobile 

and oil behavior is much like on a sand beach if the sand fraction exceeded about 40 percent. The 

burial of oil may be deep at and above the high-tide line where oil tends to persist, particularly where 

beaches are only intermittently exposed to waves. In sheltered pockets on the beach, pavements of 

asphalted sediments can form if oil accumulations are not removed because most of the oil remains 

on the surface.
3-144 Gulf of Mexico Multisale EIS

Response Considerations

First, heavy accumulations of pooled oil from the upper beach face should be removed. All 

oiled debris should be removed, but sediment removal should be limited as much as possible. Lowpressure flushing can be used to float oil away from the sediments for recovery by skimmers or 

sorbents. High-pressure spraying should be avoided because of the potential for transporting 

contaminated finer sediments (sand) to the lower intertidal or subtidal zones; mechanical reworking 

of oiled sediments from the high-tide zone to the middle intertidal zone can be effective in areas 

regularly exposed to wave activity; however, oiled sediments should not be relocated below the midtide zone. Lastly, in-place tilling may be used to reach deeply buried oil layers in the mid-tide zone 

on exposed beaches.

Exposed or Sheltered Tidal Flats

Predicted Oil Behavior

Oil does not usually adhere to the surface of sheltered or exposed tidal flats but instead 

moves across the flat and accumulates at the high-tide line. Deposition of oil on the sheltered or 

exposed flat may occur on a falling tide if concentrations are heavy. Oil would not penetrate watersaturated sediments but could penetrate burrows and desecration cracks or other crevices in muddy 

sediments in sheltered flats or coarse-grained sand in exposed flats. In areas of high suspendedsediment concentrations, the oil and sediments could mix, resulting in the deposition of 

contaminated sediments on the flats. Biological impacts could be severe.

Response Considerations

Sheltered tidal flats are high-priority areas for protection since cleanup options are limited. 

Cleanup of the sheltered tidal flat surface would be very difficult because of the soft substrate, and 

many methods may be restricted. Low-pressure flushing, vacuuming, and deployment of sorbents 

from shallow-water draft boats may be used on sheltered tidal flats. Currents and waves on 

exposed tidal flats can be effective in the natural removal of oil. Cleanup can only be done during 

low tide on exposed flats, thereby providing a narrow window of opportunity for response. The use 

of heavy machinery should be restricted on exposed tidal flats to prevent oil mixing into the 

sediments. Manual methods are preferred on exposed tidal flats.

Exposed, Solid Manmade Structures Such as Seawall/Piers

Predicted Oil Behavior

Oil is held offshore by waves reflecting off of the steep hard surfaces of exposed, solid 

manmade structures such as seawall/piers. Oil would readily adhere to the dry rough surfaces but it 

would not adhere to wet substrates. The most resistant oil would remain as a patchy band at or 

above the high-tide line.
Impact-Producing Factors and Scenario 3-145

Response Considerations

Cleanup is usually not required, and high-pressure water spraying may be conducted to 

remove risks of contamination of people or vessels or to improve aesthetics.

Mangroves

Predicted Oil Behavior

Oil can wash through mangroves if oil comes ashore at high tide. If a berm or shoreline is 

present, oil tends to concentrate and penetrate into the berm sediments or accumulated wrack/litter. 

Heavy and emulsified oil can be trapped in thickets of red mangrove prop roots or dense young 

trees. Oil readily adheres to prop roots and tree trunks. Re-oiling from resuspended or released oil 

residues may cause additional injury over time. Oiled trees start to show evidence of effects (leaf 

yellowing) weeks after oiling, and tree mortality may take months, especially for heavy oils.

Response Considerations

Oiled wrack can be removed once the threat of oiling has passed as wrack can actually 

protect the trees from direct oil contact. Sorbent boom can be placed in front of oiled forests to 

recover oil released naturally and, in most cases, no other cleanup activities are recommended. 

Where thick oil accumulations are not being naturally removed, low-pressure flushing or vacuum 

may be attempted at the outer fringe. No attempt should be made to clean interior mangroves 

except where access to the oil is possible from terrestrial areas, and it is extremely important that 

cleanup activities be conducted by boat so that disturbance of the substrate by foot traffic be 

prevented.

Seagrasses

Predicted Oil Behavior

Oil would usually pass over subtidal seagrass beds, with no direct contamination. Floating 

oil stranded on adjacent beaches can pick up sediment and then get eroded and deposited in 

adjacent seagrass beds.

Response Considerations

Care should be taken when deploying and anchoring booms to prevent physical damage to 

seagrass beds and to prevent sediment suspension and mixing with the oil and disturbance of roots 

and vegetation by foot traffic and boat activity. Seagrasses should not be cut unless species like 

sea turtles, manatees, or waterfowl are at substantial risk of contacting or ingesting oil. Also, 

dispersant use directly over subtidal seagrass beds may impact the highly sensitive communities. 

However, the use of booms or dispersants in offshore areas can reduce impacts to highly sensitive 

intertidal environments, as well as prevent shoreline stranding in mangroves that can be a chronic 

source of re-oiling of adjacent seagrass beds. Lastly, in-situ burning should only be considered 

outside the immediate vicinity of seagrass beds to protect sensitive intertidal environments because 
3-146 Gulf of Mexico Multisale EIS

burn residues can sink and the potential effects of the residue would depend on the composition and 

amount of the oil to be burned and the location where it would sink.

Bays and Estuaries

Predicted Oil Behavior

Oil can impact bottom habitats (benthic organisms) when water is shallow. Stranded oil on 

nearby shorelines can become a prolonged source for oil re-released to the water column, and tides 

and freshwater can substantially influence spilled oil movement.

Response Considerations

Reducing impacts to organisms that live on or in the sea surface is often a high priority, 

reducing the extent of impacts to sensitive nearshore subtidal or intertidal habitats should be 

considered. Spill response is not conducted from a shoreline but from water-based vessels or 

aircraft. The use of certain response options is seasonally limited to protect species with sensitive 

life histories. Lastly, adverse effects to birds would be greatest during migration and overwintering 

when birds form large flocks.

3.3 CUMULATIVE ACTIVITIES AND OCS OIL AND GAS PROGRAM SCENARIO

3.3.1 Cumulative OCS Oil and Gas Program Scenario

The Cumulative OCS Oil and Gas Program scenario includes all activities (i.e., routine 

activities projected to occur and accidental events that could occur) from past, proposed, and future 

lease sales. This includes projected activity from (1) past lease sales, including lease sales still 

scheduled for the 2012-2017 Five-Year Program but for which exploration or development has either 

not yet begun or is continuing; (2) lease sales that would be held in this Five-Year Program; and 

(3) future lease sales that would be held as a result of future Five-Year Programs (four additional 

programs are included in this cumulative analysis). Activities that take place beyond the analysis 

timeframe as a result of future lease sales are not included in this analysis. Tables 3-23 and 3-24

present projections of the major activities and impact-producing factors related to future Cumulative 

OCS Oil and Gas Program activities. Table 3-24 can be found in Chapter 3.3.1.7 below.
Impact-Producing Factors and Scenario 3-147

Table 3-23. Future Activity Projections Associated with the Cumulative OCS Oil and Gas Program 

(2017-2086), Including All Future Activities that are Projected to Occur from Past, Proposed, 

and Future Lease Sales.

Activity Planning 

Area

Offshore Subareas (m)1

Totals2

0-60 60-200 200-800 800-

1,600

1,600-

2,400 >2,400

Exploration 

and 

Delineation 

Wells

GOM 939-2,562 253-1,166 110-170 153-240 97-278 119-301 1,671-4,717

CPA/EPA 775-1,999 202-1,007 83-142 88-184 70-142 99-211 1,317-3,685

WPA 164-563 51-159 27-28 65-56 27-136 20-90 354-1,032

Development 

and 

Production 

Wells3

G

O

M

Total 4,050-9,225 1,570-4,324 912-2,034 617-1,127 446-723 633-985 8,238-18,418

Oil 438-987 164-453 446-993 280-487 230-372 310-482 1,868-3,774

Gas 2,440-5,566 894-2,457 186-415 149-288 79-126 126-194 3,874-9,046

C

P

A/

E

P

A

Total 3,170-6,634 1,139-3,558 676-1,557 490-779 405-623 595-899 6,475-14,050

Oil 354-740 122-379 326-750 240-385 207-319 289-437 1,538-3,010

Gas 1,898-3,972 645-2,015 142-327 95-152 72-110 119-179 2,971-6,755

W

P

A

Total 880-2,591 431-766 236-477 137-348 41-100 38-86 1,763-4,368

Oil 84-247 42-74 120-243 40-102 23-53 21-45 330-764

Gas 542-1,594 249-442 44-88 54-136 7-16 7-15 903-2,291

Installed 

Production 

Structures

GOM 2,168-5,121 558-1,638 36-71 26-38 16-38 23-42 2,827-6,948

CPA/EPA 1,760-3,682 432-1,347 23-54 17-26 14-21 20-30 2,266-5,160

WPA 408-1,439 126-291 13-17 9-12 2-17 3-12 561-1,788

Production 

Structures 

Removed 

Using 

Explosives

GOM 2,435-4,388 568-1,310 0 0 0 0 3,003-5,698

CPA/EPA 2,051-3,315 440-1,065 0-0 0-0 0-0 0-0 2,491-4,380

WPA 384-1,073 128-245 0-0 0-0 0-0 0-0 512-1,318

Total 

Production 

Structures 

Removed

GOM 3,381-6,148 784-1,796 39-69 36-44 20-33 21-31 4,281-8,121

CPA/EPA 2,847-4,639 608-1,459 26-54 25-31 17-22 18-24 3,541-6,229

WPA 534-1,509 176-337 13-15 11-13 3-11 3-7 740-1,892

Length of 

Installed 

Pipelines 

(km)4

GOM 2,181-15,822 1,432-

10,511 1,078-8,037 1,268-8,265 700-7,001 704-7,359 7,363-56,995

CPA/EPA 586-11,799 388-8,355 328-6,390 385-6,381 364-6,168 405-6,750 2,456-45,843

WPA 1,595-4,023 1,044-2,156 750-1,647 883-1,884 336-833 299-609 4,907-11,152

ServiceVessel Trips 

(1,000’s 

round trips)

GOM 2,443-6,998 645-2,300 284-942 213-556 134-498 187-577 3,909-11,873

CPA/EPA 1,978-5,037 496-1,892 186-722 140-389 115-306 163-440 3,079-8,788

WPA 465-1,960 150-408 98-221 72-167 19-192 23-137 830-3,085

Helicopter 

Operations 

(1,000’s 

round trips)

GOM 11,714-55,063 4,511-25,155 270-1,162 183-651 139-422 183-546 17,000-83,000

CPA/EPA 9,614-40,734 3,544-21,159 191-898 148-440 121-352 165-475 13,786-64,059

WPA 2,098-14,329 966-3,996 78-264 34-211 17-70 17-70 3,214-18,941

1

Refer to Figure 3-1. 2

Subareas totals may not add up to the planning area total because of rounding.

3

Development and Production Wells includes some exploration wells that were re-entered and completed. These wells 

were removed from the Exploration and Delineation well count.

4

Projected length of pipelines does not include length in State waters.
3-148 Gulf of Mexico Multisale EIS

It is reasonably foreseeable to assume that lease sales would continue to be proposed for 

many years to come in the Gulf of Mexico region, based on resource availability, existing 

infrastructure, and projected time lapses required for any other major energy sources to come 

online. However, the level of activities (exploration wells, production wells, and pipelines) becomes 

more speculative as time is projected into the future. The causes for this are uncertainty in oil 

prices, resource potential, cost of development, and drill rig availability, versus the amount of 

acreage leased from a lease sale. 

Therefore, these scenarios do not predict future OCS oil- and gas-related activities with 

absolute certainty, even though they were formulated using historical information and current trends 

in the oil and gas industry. Indeed, these scenarios are only approximate since future factors such 

as the contemporary economic marketplace, the availability of support facilities, and pipeline 

capacities are all unknowns. Notwithstanding these unpredictable factors, the scenarios used in this 

Multisale EIS represent the best assumptions and estimates of a set of future conditions that are 

considered reasonably foreseeable and suitable for presale impact analyses. The development 

scenarios do not represent a BOEM recommendation, preference, or endorsement of any level of 

leasing or offshore operations, or of the types, numbers, and/or locations of any onshore operations 

or facilities. Methodologies for the Cumulative OCS Oil and Gas Program scenario are similar to 

those for a regionwide or individual planning area typical lease sale scenario analysis and are 

described in detail in Chapter 3 above.

3.3.1.1 Cumulative OCS Oil and Gas Program Projected Production

As of 2014, 19.02 BBO of oil and 185.2Tcf of gas had been produced in the GOM (USDOI, 

BOEM, 2013; USDOI, BSEE, 2015e). While offshore oil production has remained fairly constant 

over the last 10 years, gas production rates offshore have declined (Figure 3-13). Projected future 

reserve/resource production estimates for the Cumulative OCS Oil and Gas Program scenario 

regionwide are 15.482-25.806 BBO and 57.875-108.513 Tcf of gas. These estimates represent all 

anticipated production from lands currently under lease plus all anticipated production from future 

lease sales over the 70-year analysis period (Table 3-1). Table 3-23 presents all anticipated activity 

associated with production from lands currently under lease in regionwide plus all anticipated activity 

associated with production from future total OCS Program (WPA, CPA, and EPA) lease sales over 

the 70-year analysis period.
Impact-Producing Factors and Scenario 3-149

Figure 3-13. OCS Oil and Gas Production Between 2003 and 2013 (USDOI, BSEE, 

2015e).

Projected future reserve/resource production estimates for the Cumulative OCS Oil and Gas 

Program scenario in the CPA and EPA are 13.707-22.152 BBO and 46.328-84.009 Tcf of gas. 

These estimates represent all anticipated production from lands currently under lease in the CPA 

and EPA plus all anticipated production from future leased lands in the CPA and EPA over the 

70-year analysis period (Table 3-1). Projected production estimates in the CPA and EPA represents 

approximately 88.5-85.8 percent of the oil and 80-77.4 percent of the gas of the cumulative OCS Oil 

and Gas Program regionwide. Table 3-23 presents all anticipated activity associated with 

production from lands currently under lease in the CPA and EPA plus all anticipated activity 

associated with production from future leased lands in the CPA and EPA over the 70-year analysis 

period.

Projected future reserve/resource production estimates for the Cumulative OCS Oil and Gas 

Program scenario in the WPA are 1.775-6.654 BBO and 11.547-24.504 Tcf of gas. These estimates 

represent all anticipated production from lands currently under lease in the WPA plus all anticipated 

production from future leased lands in the WPA over the 70-year analysis period (Table 3-1). 

Projected production estimates in the WPA represent approximately 11.5-14.2 percent of the oil and 

20-22.5 percent of the gas of the cumulative OCS Oil and Gas Program regionwide. Table 3-23

presents all anticipated activity associated with production from lands currently under lease in the 

WPA plus all anticipated activity associated with production from future leased lands in the WPA 

over the 70-year analysis period.

3.3.1.2 Cumulative Geological and Geophysical Surveys

Chapter 3.1.2.1 discusses OCS oil- and gas- related G&G survey activities. In order to 

forecast future programs as required in the cumulative case analysis, the baseline projection was 

scaled relative to the forecast of exploration wells drilled as defined by the cumulative case 

scenarios to obtain a longer term outlook. Cumulatively, G&G surveys are projected to follow the 

same trend as cumulative exploration drilling activities, which would peak in 2030-2040 and decline 
3-150 Gulf of Mexico Multisale EIS

until 2060, and remain relatively low throughout the last quarter of the 70-year analysis period. It is 

important to note that the cycling of G&G data acquisition is not driven by the 50-year life cycle of a 

single productive lease but instead would tend to respond to new production or potential new 

production driven by new technology. Consequently, some areas would be resurveyed in 2-year 

cycles, while other areas, considered nonproductive, may not be surveyed for 20 years or more. 

Conservatively, BOEM assumes that, as a result of the Cumulative OCS Oil and Gas Program, one 

HRG survey would occur for every block leased (estimated by the number of platforms predicted), 

one HRG survey would occur for every 5 km (3 mi) of pipeline laid (the average length of a pipeline 

permit), and one VSP survey would be conducted on 15 percent of all exploration and development 

wells drilled. The table below reflects a reasonable level of cumulative G&G surveying activities that 

could be expected to occur in the Gulf of Mexico (2017-2086).

3.3.1.3 Cumulative Exploration and Delineation Plans and Drilling

Chapter 3.1.2.2 describes in detail exploration and delineation activities. Since the 1950’s, 

approximately 18,954 exploratory wells have been drilled, of which 12,516 have been permanently 

abandoned (Marine Cadastre, 2015). The future projected exploration and delineation well estimate 

for the Cumulative OCS Oil and Gas Program scenario regionwide during the 70-year analysis 

period is 1,671-4,717 exploration and delineation wells drilled. Of these, 1,317-3,685 wells would be 

in the CPA/EPA and 354-1,032 wells would be in the WPA. Table 3-23 shows the estimated range 

of exploration and delineation wells by water-depth range for the Cumulative OCS Oil and Gas 

Program scenario for each planning area of the GOM. Of the wells projected under the Cumulative 

OCS Oil and Gas Program Scenario, 71-79 percent are expected to be on the continental shelf 

(0-200 m [0-656 ft] water depth) and 29-21 percent are expected in water-depth ranges >200 m 

(656 ft).

3.3.1.4 Cumulative Development and Production Drilling

Chapter 3.1.3.1 describes in detail development and production activities. Since the 1950s, 

approximately 35,029 development wells have been drilled, of which, 13,941 have been permanently 

abandoned (Marine Cadastre, 2015). The future projected development and production well 

estimate for the Cumulative OCS Oil and Gas Program Scenario regionwide is 

Survey Area

2D 

Surveys 

(mi)

2D 

Permits

3D Lease 

Blocks

3D 

Permits

Ancillary 

Permits

HRG 

Surveys

VSP 

Surveys

Regionwide

365,800-

1,036,70

0

183-506 126,800-

358,400

90-235 2,261-5,559 4,300-

18,347 1,486-3,470

CPA/EPA

362,000-

1,026,10

0

171-482 104,100-

292,100

69-186 1,813-4,128 2,757-

14,329 1,168-2,660

WPA 3,700-

10,600

12-23 22,700-

66,300

21-48 449-1,430 1,542-4,019 317-810
Impact-Producing Factors and Scenario 3-151

8,238-18,418 development and production wells drilled. Of these, 6,475-14,050 wells would be in 

the CPA/EPA and 1,763-4,368 wells would be in the WPA. Table 3-23 shows the estimated range 

of development and production wells by water-depth range for the Cumulative OCS Oil and Gas 

Program scenario for each planning area of the GOM. Of the wells projected under the Cumulative 

OCS Oil and Gas Program scenario, 68-73.5 percent are expected to be on the continental shelf 

(0-200 m [0-656 ft] water depth) and 32-26.5 percent are expected in water-depth ranges >200 m 

(656 ft).

3.3.1.5 Infrastructure Emplacement/Structure Installation and Decommissioning Activities

As of 2013, 7,020 platforms had been installed regionwide in the OCS; however, active 

platforms were estimated at only approximately 2,634 (USDOI, BSEE, 2015f; Figure 3-14). Chapter 

3.1.3.2 describes in detail infrastructure emplacement and structure installation and commissioning 

activities. The projected estimate of additional production structures expected to be installed for the 

Cumulative OCS Oil and Gas Program scenario in the WPA, CPA, and EPA during the 70-year 

analysis period is 2,827-6,948 production structures. Of these, 2,266-5,160 structures would be in 

the CPA/EPA and 561-1,788 structures would be in the WPA. Table 3-23 shows the estimated 

range of production structure installation range by water-depth range for the Cumulative OCS Oil 

and Gas Program scenario for each planning area of the GOM. Of the platforms projected under the 

Cumulative OCS Oil and Gas Program scenario, about 97 percent are expected to be on the 

continental shelf (0-200 m [0-656 ft] water depth) and 3 percent are expected in water-depth ranges 

>200 m (656 ft).

Figure 3-14. Number of Production Structures Installed and Decommissioned in Past 

Programs and the Range of Future Projections that May Occur as a Result 

of All Past, Present, and Future Actions (USDOI, BSEE 2015f).
3-152 Gulf of Mexico Multisale EIS

Bottom-Area Disturbance: Chapter 3.1.3.3.1 describes in detail infrastructure emplacement 

and structure installation and commissioning activities. Bottom area disturbance is calculated as a 

relationship between the structures projected (i.e., platforms, wells, subsea structures, and pipeline 

miles installed) and the associated disturbance of each. For the Cumulative OCS Oil and Gas 

Program scenario, between 294,821 and 605,178 ha (728,518-1,495,427 ac) of sea bottom is 

projected to be disturbed. Future activity is expected to disturb >1 percent of the seafloor 

regionwide. Of this, 241,116-460,238 ha (595,810-1,137,272 ac) of the disturbance is expected in 

the CPA/EPA and 53,705-144,939 ha (132,707-358,152 ac) of the disturbance is expected in the 

WPA.

3.3.1.6 Infrastructure Presence

Chapter 3.1.3.3 describes in detail activities associated with infrastructure presence. The 

maximum number of production structures operating simultaneously in the Cumulative OCS Oil and 

Gas Program scenario in the WPA, CPA, and EPA is 1,367 structures, including all depth ranges. 

Therefore, a maximum of 8,202 ha (20,268 ac) or approximately 6 ha (15 ac) of surface area would 

be temporarily unavailable to other activities in the OCS. To put this in perspective, <1 percent of 

the surface area of the GOM would be temporarily lost to the Cumulative OCS Oil and Gas Program. 

Additional impact-producing factors associated with offshore oil and gas infrastructure are oil spills 

and trash and debris. These are the factors most widely recognized as major threats to the 

aesthetics of coastal lands, especially recreational beaches. These factors, individually or 

collectively, may adversely affect the fishing industry, resort use, and the number and value of 

recreational beach visits.

3.3.1.7 Transport

Pipelines: Chapter 3.1.4.1 describes in detail activities associated with oil and gas 

transportation via pipelines. BOEM estimates 7,363-56,995 km (10,789-35,415 mi) of pipeline would 

be installed regionwide as a result of the activities associated with the Cumulative OCS Oil and Gas 

Program scenario (Tables 3-23 and 3-24). About 30-27 percent of the new pipeline length would be 

in water depths <60 m (197 ft) and would require burial. As of 2015, 144 pipeline landfalls currently 

exist in coastal areas of the OCS (Smith, official communication, 2015).

Barging: Chapter 3.1.4.2 describes in detail activities associated with barging. Barging is 

projected to continue to account for <1 percent of the oil transported (Table 3-24).

Tankering: The OCS oil- and gas-related tankering began in 2012. Since 2012, tankering 

has increased to account for around 2 percent of the yearly production of oil. Chapter 3.1.4.3

describes in detail activities associated with tankering. BOEM estimates 5-14 FPSO systems could 

be installed regionwide (a maximum of two per decade) as a result of the Cumulative OCS Oil and 

Gas Program scenario. Zero to five systems are projected within the WPA and 5-9 systems are 

projected within the CPA/EPA. As a result of these additional systems, up to 9 percent of the oil 

during any given year may be tankered to a processing facility (Table 3-24).
Impact-Producing Factors and Scenario 3-153

Table 3-24. Future Oil Transportation Projections Associated with the Cumulative OCS Oil and Gas 

Program (2017-2086), Including All Future Transportation that is Projected to Occur from 

Past, Proposed, and Future Lease Sales.

Activity Region

Offshore Subareas (m)1

Totals2

0-60 60-200 200-800 800-

1,600

1,600-

2,400 >2,400

Percent 

Oil Piped3

GOM 94-95% 100% 100% 100% 89.6-87.4% 87.4-85.7% 91.6-90.6%

CPA/EPA 94-95% 100% 100% 100% 97.8-96.3% 94.9-95.3% 90.8-91.0%

WPA 100% 100% 100% 100% 100-89% 100-86.4% 100-95.1%

Percent 

Oil Barged

GOM 6-5% 0% 0% 0% 0% 0% 0.2%

CPA/EPA 6-5% 0% 0% 0% 0% 0% 0.2%

WPA 0% 0% 0% 0% 0% 0% 0%

Percent 

Tankered4

GOM 0% 0% 0% 0% 10.4-12.6% 12.6-14.3% 8-9%

CPA/EPA 0% 0% 0% 0% 12.2-13.7% 5.1-4.7% 9-8.75%

WPA 0% 0% 0% 0% 0-11% 0-13.6% 0-4.85% 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.

Service Vessels: Chapter 3.1.4.4 describes in detail activities associated with service 

vessels. The Cumulative OCS Oil and Gas Program scenario estimates that 3,909,000-11,873,000 

service-vessel trips would occur regionwide over the 70-year analysis period (Table 3-23) or 

55,842-169,614 trips annually. Table 3-6 indicates 875,000 vessel trips occurred on Federal 

navigation channels, ports, and OCS oil- and gas-related waterways in 2012. Annual OCS oil- and 

gas-related vessel traffic due to cumulative OCS oil- and gas-related activity represents between 

6 and 19 percent of the total traffic in the GOM.

Helicopters: Chapter 3.1.4.5 describes in detail activities associated with helicopters. The 

Cumulative OCS Oil and Gas Program scenario estimates that 17-83 million helicopter trips would 

occur regionwide over the 70-year analysis period (Table 3-23). This equates to an average rate of 

240,000-1,190,000 operations annually.

Navigation Channels: BOEM conservatively estimates that there are approximately 

4,850 km (3,013 mi) of Federal navigation channels, bayous, and rivers potentially exposed to OCS 

traffic regionwide (Table 3-6 and Figure 3-9). No new navigation canals are expected to be created, 

however erosion of existing channels may occur. Chapter 3.1.4.6 describes in detail activities 

associated with navigation channels. Using the estimated proportion of vessel traffic associated with 

the Cumulative OCS Oil and Gas Program scenario as a measurement of erosion, BOEM 

conservatively estimates the OCS Oil and Gas Program’s contribution to bank erosion over the 

70-year cumulative scenario to be 3,135-9,524 ac (1,269-3,854 ha). This number is considered 

conservative because open waterways were included in the total length of Federal navigation 

channels, bank armoring rates may increase, vessel size was not taken into consideration, and there 

are sources of erosion to navigation canals other than vessel traffic alone.
3-154 Gulf of Mexico Multisale EIS

3.3.1.8 Discharges and Wastes 

Detailed descriptions of discharges and wastes associated with the OCS Oil and Gas 

Program activity can be found in Chapter 3.1.5. Various laws, regulations, and NTLs would likely 

minimize the discharges and wastes from OCS oil- and gas-related activities in association with the 

Cumulative OCS Oil and Gas Program scenario. Cumulative effects of discharges and wastes are 

discussed in Chapter 4.2. 

3.3.1.9 Decommissioning and Removal Operations

As of 2013, approximately 62.5 percent of structures had been decommissioned and 

removed (USDOI, BSEE, 2015f; Figure 3-14. Chapter 3.1.6 describes in detail decommissioning 

and removal operations. Table 3-23 shows the forecasted platform removals by water-depth range 

for the Cumulative OCS Oil and Gas Program scenario for each planning area of the GOM. Of the 

4,281-8121 production structures estimated to be removed from the GOM in the Cumulative Oil and 

Gas Program scenario, 3,003-5,698 production structures (installed landward of the 800-m [2,625-ft] 

isobath) would likely to be removed using explosives.

3.3.1.10 Coastal Infrastructure 

Refer to Table 3-4 for information on existing coastal infrastructure that services the OCS Oil 

and Gas Program. Chapter 3.1.7 describes coastal infrastructure in detail. The Cumulative OCS Oil 

and Gas Program scenario estimates no additional: service bases, heliports, platform fabrication 

yards, shipyards, or pipe-coating facilities and yards.

Expectations for new gas processing facilities being built (as a direct result of the Cumulative 

OCS Oil and Gas Program) are dependent on long-term market trends that are not easily predicable 

over the next 70 years. Existing facilities would likely experience equipment switch-outs or upgrades 

during this time. BOEM projects that expansions at existing LNG facilities and the construction of 

new facilities would not occur as a direct result of the cumulative OCS Oil and Gas Program. New 

refineries may be built, but there has been a trend toward constructing simple refineries instead of 

complex refineries.

3.3.1.11 Air Emissions

Chapter 3.1.8 describes in detail activities associated with the production of air emissions. 

BOEM is responsible for determining if air pollutant emissions from offshore oil and gas activities in 

the Gulf of Mexico influence the NAAQS’ compliance status of Texas, Louisiana, Mississippi, 

Alabama, and Florida. As such, BOEM would continue to inventory emissions and model emissions 

whenever the USEPA updates the NAAQS. Effects to air quality from the Cumulative OCS Oil and 

Gas Program are discussed in Chapter 4.1. 
Impact-Producing Factors and Scenario 3-155

3.3.2 Non-OCS Oil- and Gas-Related Impact-Producing Factors

The impact-producing factors considered in this chapter are defined as other past, present, 

and reasonably foreseeable future activities occurring within the same geographic range and within 

the same timeframes as the aforementioned projected routine activities and potential accidental 

events, but they are not related to the Cumulative OCS Oil and Gas Program. This chapter 

describes other impact-producing factors that could potentially affect an environmental or 

socioeconomic resource in addition to OCS oil- and gas-related activity.

While the scenario developed for the Cumulative OCS Oil and Gas Program scenario 

forecasts 70 years of activities, the scenarios developed as part of this chapter vary in the length of 

time projected depending on what would be considered reasonably foreseeable by impact-producing 

factors based on the data available and the ability to predict future actions without being speculative.

3.3.2.1 State Oil and Gas Activity

All of the five Gulf Coast States have had some historical oil and gas exploration activity and, 

with the exception of Florida and Mississippi, all currently produce oil and gas in State waters. The 

coastal infrastructure that supports the OCS Program also supports State oil and gas activities.

State oil and gas infrastructure consists of the wells that extract hydrocarbon resources, 

facilities that produce and treat the raw product, pipelines that transport the product to refineries and 

gas plants for further processing, and additional pipelines that transport finished product to points of 

storage and final consumption. The type and size of infrastructure that supports production depends 

upon the size, type, and location of the producing field, the time of development, and the life cycle 

stage of operations.

Texas

The first offshore well in Texas was drilled in 1938, but the first oil discovery was not made 

until 1941 off of Jefferson County. The Oil and Gas Division of the Railroad Commission of Texas is 

the agency charged by the Texas Legislature with the regulation of the oil and gas industry (i.e., 

exploration, production, and transportation) in the State of Texas. According to the Railroad 

Commission of Texas, since June 2015 cumulative total State offshore production of oil was 

reported at over 42 million bbl and offshore gas production totals were reported at over 4.1 billion 

Mcf (Railroad Commission of Texas, 2015). Texas was the leading crude-oil producing state in the 

Nation in 2013 and exceeded production levels even from the Federal offshore areas (USDOE, 

Energy Information Administration, 2014b).

The Lands and Minerals Division of the Texas General Land Office holds lease sales for oil 

and gas on State lands, and the Texas General Land Office manages Texas State resources for the 

benefit of public education. The Texas General Land Office generally holds lease sales every 4 

months in January, April, July, and October. The Texas General Land Office’s Mineral Leasing 

Division uses a sealed bid process for the leasing of State lands. BOEM expects that Texas would 
3-156 Gulf of Mexico Multisale EIS

conduct regular oil and gas lease sales in State waters during the next 70 years, although the lease 

sales’ regularity could differ from current practices.

Louisiana

Louisiana has been the second most important oil- and gas-producing state after Alaska. Oil 

production in Louisiana began in 1902, with the first oil production in the coastal zone in 1926. The 

State of Louisiana issued its first offshore oil and gas lease in 1936, and in 1937 the Pure Oil 

Company discovered the first Louisiana oil field 1.2 mi (1.9 km) offshore of Cameron Parish using a 

platform built on timber pilings in water 15 ft (4.6 m) deep. Southern Louisiana produces mostly oil 

and northern Louisiana produces mostly gas.

The nine contiguous parishes of the coastal zone produced more than 50 percent of the 

State’s oil during the 1950’s. Oil and gas production peaked in the 1970’s in Louisiana. Over the 

last 60 years, Louisiana averaged around 27 MMbbl of oil and 12 Tcf of gas per year (State of 

Louisiana, Dept. of Natural Resources, 2015a and 2015b).

Louisiana’s leasing procedure is carried out by the Petroleum Lands Division of the Office of 

Mineral Resources within the Louisiana Department of Natural Resources and proceeds along the 

following procedural steps (State of Louisiana, Dept. of Natural Resources, 2015c):

(1) industry nominates acreage for leasing every month (by law, nominated tracts 

cannot exceed 5,000 ac [2,023 ha], but by Mineral Board policy, the size limit of 

a nominated tract is further limited to only 2,500 ac [1,012 ha].); 

(2) the nominated tracts are then advertised in official State and parish journals; 

(3) competitive, sealed bidding then takes place on bonus, royalty, and rental to be 

received by the State (The sealed bids are opened and read into the record at a 

public meeting of the Louisiana Mineral Board at the time and place 

advertised.); and 

(4) if it determines that the bids are sufficient, the Louisiana Mineral Board awards 

the leases to the highest bidder after evaluating data provided from staff 

geologists from the Geology and Engineering Division of the Office of Mineral 

Resources. The term of the lease is limited to 3 years for inland tracts and 

5 years for offshore tracts.

BOEM expects that Louisiana would conduct regular oil and gas lease sales in State waters 

during the next 70 years.

Mississippi

At present, Mississippi only has an onshore oil and gas leasing program; however, it is 

expected that the State would start issuing leases for offshore activity in State waters in the near 
Impact-Producing Factors and Scenario 3-157

future. In 2004, the Mississippi Legislature limited offshore natural oil and gas exploration to areas 

located predominantly south of the barrier islands. After this legislation went into effect, the State 

Mineral Leasing Office was moved to the Mississippi Development Authority, which was given the 

responsibility to publish rules and regulations regarding offshore mineral leasing and seismic activity. 

The rules and regulations would allow the State of Mississippi to issue seismic permits and lease 

mineral rights for natural gas and oil exploration and production (Mississippi Energy Future, 2012). 

On December 19, 2011, the Mississippi Development Authority published draft regulations; the 

public comment period closed on January 20, 2012 (Mississippi Development Authority, 2011). 

However, recent efforts to open Mississippi State waters for G&G and leasing activities have been 

challenged in court (Davis, 2014).

Most of the State’s onshore crude oil is located in southern Mississippi. Compared with 

other states, the production is small and accounts for a 1.2-percent share of U.S. production. Over 

approximately the last 30 years, Mississippi has produced on average 24 MMbbl of oil and 116 Bcf 

of natural gas per year (USDOE, Energy Information Administration, 2015e). Mississippi falls behind 

several other states and is ranked 12th in gas production. In 2007, Mississippi was selected by the 

DOE as a new storage site for the Strategic Petroleum Reserve. The new site is a group of salt 

domes located inland in Richton, Mississippi (USDOE, Energy Information Administration, 2015e).

BOEM expects Mississippi to institute a lease sale program in the near future and to begin 

leasing in State waters during the next 70 years.

Alabama

The State Oil and Gas Board of Alabama is the regulatory agency of the State of Alabama 

with statutory charge of oil and gas development. The earliest exploration wells in Alabama’s 

offshore waters were drilled in Mobile Bay by Gulf Refining Company in late 1951 and early 1952. 

These two early wells were plugged and abandoned at depths of 10,000 and 11,000 ft (3,048 and 

3,253 m) after failing to encounter any substantial show of oil and gas. A period of more than 

27 years lapsed before another test well was drilled, but this next attempt was successful and led to 

the active drilling and development of the large gas reserve lying more than 20,000 ft (6,096 m) 

below coastal waters (State of Alabama, Oil and Gas Board, 2015).

From 1989 to 2014, a total of 8,278,884 MMcf of gas has been produced in State waters, 

averaging approximately 331,155 MMcf of gas production per year. From 1989 to 2012, a total of 

293,730,516 bbl of oil were produced, averaging approximately 12,770,892 bbl/yr (State of Alabama, 

Oil and Gas Board, 2015).

Alabama has no established schedule of lease sales. The limited number of tracts in State 

waters has resulted in the State not holding regularly scheduled lease sales. The last lease sale 

was held in 1997. 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 next 70 years.
3-158 Gulf of Mexico Multisale EIS

Florida

The Florida Department of Environmental Protection’s Mining Mitigation and Delineation 

Program is the permitting authority for the exploration and production of oil and gas in Florida. By 

1944, Florida had leased much of its State waters along the Gulf Coast for oil and gas exploration 

and development. The first Federal lease sale off Florida (Lease Sale 5) was held in 1959 and 

resulted in 23 blocks leased and three wells drilled off south Florida. The next Federal lease sale 

(Lease Sale 32) was not be held until 1973 (Reef Relief, 2015).

In the late 1970’s and early 1980’s, Florida encouraged and supported efforts to find and 

produce oil and gas off its shores. As late as 1983, Getty Oil drilled a 1,200-ft (366-m) exploration 

well in <25 ft (8 m) of water near Pensacola. This “zero-discharge,” heavily bonded and monitored 

exploration well reportedly yielded a natural gas find. This was the last oil and gas exploration well 

drilled in State waters (Reef Relief, 2015).

A total of 19 wells were drilled in Florida State waters from 1947 to 1983 (State of Florida, 

Dept. of Natural Resources, 1991). Offshore exploratory drilling in Federal waters of the EPA 

included six wells completed in 1988 and 1989; one of these was the discovery in the Destin Dome 

Area and was classified by the Federal Government as a producible field (State of Florida, Dept. of 

Natural Resources, 1991). In July 1990, all offshore drilling activity in Florida State waters was 

prohibited and the State’s policy on offshore oil and gas drilling changed. Since 1989, the Florida 

State Congress has prohibited new leasing off Florida in the EPA. In May 2002, DOI announced an 

agreement in principle to settle litigation, and the two leases remaining in the unit, held by Murphy 

Oil, would be suspended until at least 2012 and could not be developed without agreement with DOI 

and Florida. The Gulf of Mexico Energy Security Act of 2006 (GOMESA) extended the moratorium 

on new oil and gas leasing off of Florida until June 30, 2022. In January 2003, Florida received 

notice from the U.S. Department of Commerce that Chevron’s appeal of Florida’s CZMA objection to 

the DPP for the Destin Dome 56 Unit had been dismissed for good cause (i.e., Chevron withdrew its 

applications). The two leases held by Murphy Oil in the Destin Dome Area remain active. The 

GOMESA also implemented revenue sharing with petroleum-producing coastal states; however, 

Florida is not considered a producing state, thus it does not share in revenues. The GOMESA also 

required DOI to develop regulations to grant existing leases within 100 mi (161 km) of Florida in the 

EPA with credits they could use to buy leases in other areas of the Gulf of Mexico or use for 

payment of debt should they not be allowed to develop their lease in the EPA.

With current State policy and regulations prohibiting oil and gas exploration and development 

in State waters, BOEM does not expect Florida to institute a lease sale program in the near future. If 

State policy and regulations change and the moratorium is allowed to expire, the potential for a lease 

sale in State waters could be a possibility during the next 70 years.

3.3.2.1.1 State Pipeline Infrastructure

The existing pipeline network in the Gulf Coast States is the most extensive in the world and 

has unused capacity (Cranswick, 2001). The network carries oil and gas onshore and inland to 
Impact-Producing Factors and Scenario 3-159

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. However, 

as discussed in Chapter 3.1.4.1, there is spare capacity in the existing pipeline infrastructure to 

move oil and gas to market, and deepwater ports can serve onshore facilities, including intrastate as 

well as interstate pipelines.

Texas: There are 14 pipelines that make landfall on the Texas shoreline. The Railroad 

Commission of Texas reports that there are slightly over 150,000 mi (242,402 km) of petroleumproduct-carrying intrastate pipelines, but no differentiation was provided for the length of pipeline in 

the 11 coastal counties contiguous to the GOM (Railroad Commission of Texas, 2009).

Louisiana: There are currently 122 pipeline landfalls in the Louisiana Coastal Area 

(Table 3-4).

Alabama: There are currently five pipeline landfalls on the Alabama shoreline. This includes 

one natural gas pipeline that runs from Alabama to Florida.

Mississippi: There are currently three pipeline landfalls on the Mississippi shoreline.

Florida: There is currently one pipeline landfall on the shore of Florida. This is a natural gas 

pipeline that runs from Alabama to Florida.

3.3.2.1.2 Artificial Reefs

Use of artificial reefs to enhance fisheries along the U.S. coastline was documented as early 

as the mid-19th century (Stone, 1974; McGurrin et al., 1989; Christian et al., 1998). For nearly 

200 years, purpose-built structures (e.g., wooden huts, cinder block reefs, and concrete pyramids) 

and obsolete materials (e.g., decommissioned vessels and damaged concrete pipe) have been 

intentionally deposited in estuarine and marine environments to add bottom relief, attract fishes, and 

improve angler access and success. As a result of research into the potential benefits and adverse 

impacts resulting from specific artificial reef designs, materials, and siting, the National Artificial Reef 

Plan and subsequent revision in 2007 were developed to provide guidance to artificial reef 

coordinators, fisheries managers, and other parties on recommended siting, construction, 

management, and monitoring of artificial reefs. The Secretary of the Army, through the COE, is 

responsible for the artificial reef permitting process and for coordination of the appropriate State and 

Federal agencies (USDOC, NOAA, 2007). The Wallop-Breaux Amendment provided increased 

Federal funding to State agencies for sport fish restoration, contributing to the National Fisheries 

Enhancement Act’s objectives through support of habitat enhancement projects, research, and 

monitoring (Christian et al., 1998).
3-160 Gulf of Mexico Multisale EIS

Offshore oil and gas platforms have been contributing hard substrate to the GOM since the 

1930’s, and fishermen quickly found fishing success was enhanced in the vicinity of OCS oil- and 

gas-related structures (State of Louisiana, Dept. of Wildlife and Fisheries, 1987). By the late-1970’s 

some artificial reef advocates and recreational fishermen had begun viewing the decommissioning 

and removal of OCS oil- and gas-related structures as a lost opportunity. The increased interest and 

participation in fishing at offshore oil and gas platforms and national support for effective artificial 

reef development coincided with research and fisheries management efforts, which led to passage 

of the National Fishing Enhancement Act of 1984 and the development of the first National Artificial 

Reef Plan. In 1987, Louisiana published a State artificial reef plan that specifically addressed the 

need to support public interest through development of artificial reef planning areas and the addition 

of decommissioned OCS platforms as artificial reef substrate (State of Louisiana, Dept. of Wildlife 

and Fisheries, 1987). Texas’ Artificial Reef Act of 1989 explicitly identified decommissioned 

platforms as the preferred substrate for the construction of artificial reefs (State of Texas, Parks and 

Wildlife Dept., 1990). Currently, all five Gulf Coast States have active artificial reef programs, which 

develop and manage artificial reefs on the Federal OCS.

The OCSLA and implementing regulations establish decommissioning obligations for 

lessees, including the removal of platforms. The Rigs-to-Reefs Policy provides a means by which 

lessees may request a waiver to the removal requirement. For additional information, refer to 

Chapter 3.1.6.2. Since the first Rigs-to-Reefs conversion, approximately 11 percent of the platforms 

decommissioned from the Gulf of Mexico OCS have been redeployed within designated State 

artificial reefs. Scientific and public interest in the ecology of offshore structures and the potential 

benefits of contributing hard substrate to a predominantly soft bottom environment have led to 

increased emphasis on the development of artificial reefs. The current paradigm posits oil and gas 

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; and Dance et al., 2011). 

However, determination of specific and cumulative impacts resulting from construction of artificial 

reefs within permitted areas is very difficult. As recommended by the National Artificial Reef Plan 

(USDOC, NOAA, 2007), well-defined objectives, clear management strategies, and long-term 

monitoring are critical elements of an artificial reef program and are necessary if managers intend to 

use artificial reefs as a fisheries management tool.

3.3.2.2 Marine Vessel Activity

3.3.2.2.1 Marine Transportation

Under current conditions, freight and cruise ship passenger marine transportation within the 

analysis area should continue to grow at a modest rate or remain relatively unchanged based on 

historical freight 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, 2015a). Tankers carrying 

mostly petrochemicals account for about 60 percent of the vessel calls in the Gulf of Mexico. Drybulk vessels, including bulk vessels, bulk containerships, cement carriers, ore carriers, and woodchip carriers, account for another 17 percent of the vessel calls. The GOM also supports a popular 
Impact-Producing Factors and Scenario 3-161

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. is increasing as a whole, and total port 

calls within the GOM is also increasing. Gulf of Mexico port calls represent approximately 

33 percent of total U.S. port calls. Trends for GOM port calls relative to total U.S. port calls shows 

an approximate 3 percent average increase of GOM port calls between 2003 and 2012, from 

18,034 to 24,730 port calls (USDOT, MARAD, 2015a) (Table 3-25).

Table 3-25. Number of Vessel Calls at U.S. Gulf Ports Between 2002 and 20111. 

Vessel Type 2003 2004 2005 2006 2007 2008 2009 2010 2011 201211

TankerProduct2,3 5,143 5,764 6,171 6,594 6,784 6,597 6,451 7,000 8,413

15,032

Tanker-Crude2,4 4,227 4,361 4,303 4,343 4,614 4,574 4,502 5,150 5,626

Container5 1,263 1,284 1,378 1,354 1,306 1,372 1,641 1,934 2,338 2,047

Dry Bulk6 4,837 4,959 4,575 5,289 4,988 4,563 4,021 3,475 3,917 4,888

RO-RO (Roll-on 

Roll-off)7 398 370 337 423 386 374 491 549 566 547

Gas8 624 548 558 622 628 462 441 500 604 612

Combo9 375 258 201 155 135 116 102 94 66 NA

General10 1,167 1,141 1,160 1,246 1,362 1,363 1,300 1,387 1,459 1,604

All Types 18,034 18,685 18,683 20,026 20,203 19,421 18,949 20,089 22,989 24,730

1

The data in this report are only for oceangoing self-propelled vessels of 10,000 deadweight (DWT) capacity 

or greater. In 2005, these vessels accounted for 98 percent of the capacity calling at U.S. ports.

2

Petroleum tankers and chemical tankers.

3

10,000-69,999 DWT. 4

>70,000 DWT.

5

Container carriers, refrigerated container carriers.

6

Bulk vessels, bulk containerships, cement carriers, ore carriers, wood-chip carriers. 7

RO/RO vessels, RO/RO containerships, vehicle carriers.

8

Liquefied natural gas carriers, liquefied natural gas/liquefied petroleum gas carriers, liquefied petroleum 

carriers.

9

Ore/bulk/oil carriers, bulk/oil carriers.

10General cargo carriers, partial containerships, refrigerated ships, barge carriers, livestock carriers.

11In 2012, product and crude tankers were not distinguished.

Source: USDOT, MARAD, 2015a.

It is expected that the usage of GOM ports would continue to increase by approximately 

3 percent annually over the next 50 years. As such, it is anticipated that port calls by all ship types 

would be bounded annually by a lower limit of current use and an upper limit of approximately 

99,417 vessel port calls per year.
3-162 Gulf of Mexico Multisale EIS

3.3.2.2.2 Other Marine Vessel Traffic

Non-OCS oil- and gas-related vessels other than those listed in Chapter 3.3.2.2.1 utilize the 

GOM. These ships include research vessels, recreational vessels and commercial vessels. 

Commercial and recreational fishing in the Gulf of Mexico are regulated by the NMFS. For more 

information on recreational fishing vessels, refer to Chapter 4.11. For more information on 

commercial fishing vessels, refer to Chapter 4.10. Research activities, including surveys, genetic 

research, capture, relocation, or telemetric monitoring, may affect organisms or ecosystems in the 

GOM. If any of these activities could involve the take of an endangered species, the activity is 

required to obtain a permit through the NMFS. Vessels involved in the photography of marine 

mammals may also require a permit through the NMFS. 

3.3.2.2.3 Anchoring

Any of the non-OCS oil- and gas-related vessels listed in Chapter 3.3.2.2 could affect 

marine resources by anchoring. Effects would be similar to those discussed in the OCS oil- and 

gas-related anchoring Chapter 3.1.3.3.1. While commercial vessels acting under regulation may be

more alert of sensitive areas, recreational vessels may be less aware of sensitive areas. For 

example, OCS oil- and gas-related vessels are required to survey for undiscovered archaeological 

resources; however, these resources may be damaged by anchors of non-OCS oil- and gas-related 

vessels that do not perform surveys. 

3.3.2.2.4 Tankering

Non-OCS oil- and gas-related tankering includes ships carrying crude or ships carrying 

product. Overall, tankering (including U.S. ships and foreign ships) in the U.S. increased by 

28 percent between 2003 and 2011 (USDOT, MARAD, 2013). While U.S. tankering port of calls 

declined between 2003 and 2011, foreign ship tankering port of calls increased; as listed below.

Ship Origin 2003 2011

U.S. Tankers 3,759 2,956

Foreign Tankers 14,744 20,722

Source: USDOT, MARAD, 2013.

Due to the double-hulled ships’ ability to reduce or prevent oil spills, double-hulled ships 

have replaced almost all single-hulled ships. In 2003, 60-70 percent of all tankers were double 

hulled, but by 2011, 97-100 percent of all tankers were double hulled.

3.3.2.3 Non-OCS Oil- and Gas-Related Wastes and Discharges

Current and historic marine activities, unrelated to the OCS oil and gas program, are 

considered in the cumulative scenario for water quality in the GOM. These include regulated 

effluents from State oil and gas activities and the discharge of bilge, ballast water, and sanitary 

wastes from commercial shipping, similar to OCS oil- and gas-related service vessels (Chapter 

3.1.5). Other non-OCS oil- and gas-related wastes are associated with dredged material disposal, 
Impact-Producing Factors and Scenario 3-163

potentially polluting shipwrecks, military activities, disposal of military chemical weapons and 

industrial wastes, land-based discharges, and non-OCS oil- and gas-related sources of trash and 

debris.

3.3.2.3.1 Potentially Polluting Shipwrecks

There are thousands of shipwrecks in U.S. waters. Some of the vessels involved in those 

wrecks are likely to contain oil, as fuel and possibly cargo, and may eventually result in pollution to 

the marine environment. Warships and cargo vessels sunk in wartime may also contain munitions, 

including explosives and chemical warfare agents, which may pose a continued threat because of 

their chemical composition. The NOAA maintains a large database of shipwrecks, dumpsites, 

navigational obstructions, underwater archaeological sites, and other underwater cultural resources 

(USDOC, NOAA, 2013b). This internal database, Resources and Undersea Threats, includes 

approximately 20,000 shipwrecks in U.S. waters. Shipwrecks in the Resources and Undersea 

Threats database were ranked to identify the most ecologically and economically significant, 

potentially polluting wrecks in U.S. waters for inclusion in the Remediation of Underwater Legacy 

Environmental Threats Program. Under this Program, wrecks are ranked based on age, size, hull 

material, type, location, historical information on the vessel, engineering analysis, archaeological site 

formation, whether they are currently leaking, and modeling of the trajectory, fate, and 

consequences of an oil release from a shipwreck. The NOAA identified 87 priority wrecks on the 

2012 Remediation of Underwater Legacy Environmental Threats Program (those with the highest 

probability of discharge). Of these, 53 sank during an act of war and 34 sank as a result of collision, 

fire, grounding, storms, or other causes. Priority wrecks located in the Gulf of Mexico include R.W. 

Gallagher, which contains 80,855 bbl of Bunker C fuel oil, located about 40 mi (64 km) south of 

Terrebonne Parish, Louisiana, and Joseph M. Cudahy, which contains 77,444 bbl of crude and 

lubricating oil, located about 65 mi (105 km) northwest of Key West, Florida. The NOAA Wreck Oil 

Removal Program provides for the removal of oil from priority wrecks, where feasible.

Another shipwreck of note is Tank Barge DBL 152, which, on November 11, 2005, struck the 

submerged remains of a pipeline service platform in West Cameron Block 229 (about 50 mi [80 km] 

southeast of Sabine Pass, Texas). The platform had previously collapsed during Hurricane Rita. 

The barge was carrying a cargo of approximately 119,793 bbl of a blended mixture of low-API 

gravity oil (i.e. heavy oil, likely to sink). A portion of the oil was released at the point of impact, which 

sank to the seafloor. The barge was towed toward shallow water to facilitate salvage; however, it 

grounded and capsized approximately 12 mi (19 km) to the west-northwest, releasing additional oil 

to the seafloor. An estimated 45,846 bbl of oil were released during the incident, of which about 

2,355 bbl were recovered by divers. In January 2006, recovery of additional oil was deemed 

infeasible and cleanup operations were discontinued, leaving approximately 43,491 bbl of oil 

unrecovered on the seafloor (USDOC, NOAA, 2013c).

3.3.2.3.2 Discharges Associated with Military Activities

A full description of military activities is discussed in Chapter 3.3.2.6.1 below. Military 

operations within military warning areas (MWAs) and Eglin Water Test Areas (EWTAs) vary in types 
3-164 Gulf of Mexico Multisale EIS

of missions performed and their frequency of use. Such missions may include carrier maneuvers, 

missile testing, rocket firing, pilot training, air-to-air gunnery, air-to-surface gunnery, minesweeping 

operations, submarine operations, air combat maneuvers, aerobatic training, and instrument training. 

To eliminate potential impacts from multiple-use conflicts related to the warning and test areas, a 

standard Military Areas Stipulation is routinely applied to all GOM leases (example in 

Appendix D.3).

Between the years of 1995 through 1999, Eglin Air Force Base in Florida conducted nearly 

39,000 training sorties per year in the eastern Gulf. Potential impacts from these activities are 

discussed in the Eglin Gulf Test and Training Range, Final Programmatic Environmental 

Assessment (Air Force Air Armament Center, 2002). These military activities may result in marine 

impacts from chaff, fuel releases, flares, chemical materials, and debris.

Chaff, which is composed of short aluminum fibers similar in appearance to human hair, 

metalized glass fiber, or plastic, is dispensed by military aircraft as a countermeasure to distract 

radar-guided missiles from their targets. The Air Force Air Armament Center identified a remote 

potential that chaff could be mistaken as a food source and be ingested by aquatic organisms; 

however, the quantity of chaff used was not stated (Air Force Air Armament Center, 2002, 

page 4-18).

During in-flight emergencies, fuel may be released in the air or a fuel tank may be jettisoned 

and impact the surface. Drones may also be shot down and release fuel upon surface impact. The 

type of fuel used, JP-8, is very volatile and, when released at altitude, evaporates quickly. The Air 

Force Air Armament Center concluded that temporary localized effects to air and water quality may 

result from fuel releases; however, the frequency of fuel releases is extremely low (Air Force Air 

Armament Center, 2002, pages ES-1 and ES-2).

Flares may be ejected from aircraft to confuse and divert enemy heat-seeking or heatsensitive missiles, and may also be used to illuminate surface areas during nighttime operations. 

Flares are composed primarily of aluminum, magnesium, and TeflonTM. Upon burning, the 

magnesium (as magnesium oxide) in the flare may be deposited on the water surface. The Air 

Force Air Armament Center characterizes the impact to water from flares to be less than the natural 

concentrations of magnesium found in the Gulf (Air Force Air Armament Center, 2002, pages 4-20 

and 4-21).

The Air Force Air Armament Center stated that chemical materials are introduced into the 

marine environment through drones, gun ammunition, missiles, chaff, flares, smokes and 

obscurants. The Air Force Armament Center concluded that potential chemical contamination 

concentrations were extremely low and not likely to impact marine species.

Debris may be released into the GOM as a result of military activities, including ordnance 

and shrapnel deposits from bombs and missiles, drones, chaff and flare cartridges, and intact inert 

bombs. This debris generally falls into the major categories of aluminum, steel, plastic, concrete, 
Impact-Producing Factors and Scenario 3-165

and other components (i.e., copper and lead) and originates largely from inert bombs, missiles, and 

downed drones (Air Force Armament Center, 2002, page 2-21).

3.3.2.3.3 Historical Chemical Weapon Disposal Areas

After World War I, chemical weapons were routinely disposed of in the world’s oceans, 

including the GOM. In some instances, conventional explosives and radiological wastes were 

dumped along with chemical weapons. Army records document several instances of mustard and 

phosgene bombs being disposed of in the Gulf of Mexico, originating from New Orleans, Louisiana, 

and Mobile, Alabama. Chemical weapons disposed of in other locations, and potentially in the Gulf 

of Mexico, contained hydrogen cyanide, arsenic trichloride, cyanogen chloride, lewisite, tabun, sarin, 

and VX (Bearden, 2007).

Six former explosives dumping areas are noted on NOAA’s chart of the Gulf of Mexico 

(USDOC, NOAA, 2015a) and likely contain disposed chemical weapons. These include two areas 

offshore Texas (about 65 nmi [75 mi; 120 km] southeast of Aransas Pass and about 100 nmi 

[115 mi;185 km] south of Galveston); two areas offshore Louisiana (both about 35-40 nmi 

[42-46 mi;65-74 km] south of the mouth of the Mississippi River); one area offshore Alabama (about 

70 nmi [81 mi; 130 km] southeast of Mobile Bay); and one offshore Florida (about 130 nmi [150 mi; 

241 km] west of Tampa Bay).

The Marine Protection, Research, and Sanctuaries Act of 1972, also known as the Ocean 

Dumping Act, was promulgated to regulate ocean dumping and to set aside certain areas as national 

marine sanctuaries. Section 101 of the Act (33 U.S.C. § 1411) prohibits ocean dumping, except as 

authorized by permit issued by the USEPA pursuant to Section 102 (33 U.S.C. § 1412). Section 102 

specifically states that radiological, chemical, and biological warfare agents, high-level radioactive 

waste, and medical waste would not be permitted for ocean disposal after 1972.

3.3.2.3.4 Historical Industrial Waste Dumping Areas

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, 2015b).

Section 102 of the Ocean Dumping Act (33 U.S.C. § 1412) authorizes the issuance of 

permits for ocean disposal of certain waste streams and requires that the USEPA determine that 

such dumping will not unreasonably degrade or endanger human health, welfare, or amenities, or 

the marine environment, ecological systems, or economic potentialities.

In 1973, the USEPA permitted two interim industrial waste disposal sites in the Gulf of 

Mexico, the charting of which has been maintained by the NOAA. Disposal Site A, located within the 

WPA, is situated on the upper part of the Texas-Louisiana continental shelf, about 125 nmi (144 mi; 

232 km) south of Galveston, Texas. Disposal Site B is located in the CPA off the western side of the 
3-166 Gulf of Mexico Multisale EIS

Mississippi Delta about 60 nmi (75 mi; 120 km) south of the mouth of the Mississippi River. These 

sites are each approximately 300 mi2 (777 km2

) in area.

The National Academy of Sciences’ report, Assessing Potential Ocean Pollutants (National 

Academy of Sciences, 1975), provides an understanding of the disposal site conditions. At Site A 

(depth of about 610 m [2,001 ft]), uncontained wastes were discharged through a submerged pipe 

into the turbulent wake of a barge. At Site B (depth of about 655 m [2,149 ft]), 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 bbl contained 

chlorinated hydrocarbons. Chlorinated hydrocarbons were used during the Vietnam War to produce 

pesticides and defoliants (e.g., Agent Orange).

An additional industrial waste site is shown on NOAA’s chart of the Gulf of Mexico (USDOC, 

NOAA, 2015a), and it is centered about 180 nmi (207 mi; 333 km) south-southeast of Galveston, 

Texas. This site, which is labeled on NOAA’s chart as “organochlorine wastes,” is approximately 

2,300 mi2 (5,957 km2

) in area and lies in 500-1,000 m (1,640-3,281 ft) of water. This site was not 

discussed in the National Academy of Sciences’ report and may be subsequent disposal of the same 

waste stream at Site B discussed above.

3.3.2.3.5 Dredged Material Disposal

Dredged material is described in 33 CFR part 324 as any material excavated or dredged 

from navigable waters of the United States. Materials from maintenance dredging are primarily 

disposed of offshore on existing dredged-material disposal areas and in ocean dredged-material 

disposal sites (ODMDSs). Additional dredged-material disposal areas for maintenance or newproject dredging are developed as needed and must be evaluated and permitted by the U.S. Army 

Corps of Engineers (COE) and relevant State agencies prior to construction. The ODMDSs are 

regulated by the USEPA under the Clean Water Act and the Marine Protection, Research, and 

Sanctuaries Act.

If funds are available, the COE uses dredge materials beneficially for restoring and creating 

habitat, for beach nourishment projects, and for industrial and commercial development (Chapter 

3.3.2.8.3). The applicant would need funds to cover the excess cost over the least cost 

environmentally acceptable alternative (the Federal Standard). The material must also be suitable 

for the particular beneficial use. Virtually all ocean dumping that occurs today is maintenance 

dredging of sediments from the bottom of channels and bodies of water in order to maintain 

adequate channel depth for navigation and berthing. There are four authorized open-water disposal 

areas in Louisiana and Mississippi along stretches of the main Gulf Intracoastal Waterway (GIWW) 

between Louisiana and Mississippi: in Louisiana, Disposal Area 66 (1,593 ac; 645 ha); and in 

Mississippi, Disposal Area 65A (1,962 ac; 794 ha), Disposal Area 65B (815 ac; 330 ha), and 
Impact-Producing Factors and Scenario 3-167

Disposal Area 65C (176 ac; 71 ha) (U.S. Dept. of the Army, COE, 2008, Table 1). Dredged 

materials from the GIWW are disposed of at these locations. The ODMDSs utilized by the COE are 

located in the cumulative activities area and can be found on the Ocean Disposal Database website 

(U.S. Dept. of the Army, COE, 2015a).

There are two primary Federal environmental statutes governing dredge material disposal. 

The Marine Protection, Research, and Sanctuaries Act (also called the Ocean Dumping Act) govern 

transportation for the purpose of disposal into ocean waters. Section 404 of the Clean Water Act 

governs the discharge of dredged or fill material into U.S. coastal and inland waters. The USEPA 

and COE are jointly responsible for the management and monitoring of ocean disposal sites. The 

responsibilities are divided as follows: (1) the COE issues permits under the Clean Water Act and 

the Marine Protection, Research, and Sanctuaries Act; (2) the USEPA has lead for establishing 

environmental guidelines/criteria that must be met to receive a permit under either statute; 

(3) permits for ODMDS disposal are subject to USEPA review and concurrence; and (4) the USEPA 

is responsible for designating ODMDSs.

The COE’s Ocean Disposal Database reports the amount of dredged material disposed in 

ODMDSs by district (U.S. Dept. of the Army, COE, 2015a). Table 3-26 shows the quantities of 

dredged materials disposed of in ODMDSs between 2004 and 2013 by the Galveston, New Orleans, 

and Mobile Districts.

Table 3-26. Quantities of Dredged Materials Disposed of in Ocean Dredged-Material Disposal Sites 

Between 2004 and 2013.

Year

New Orleans District Galveston District Mobile District

yd3 m3 yd3 m3 yd3 m3

2004 21,156,300 16,175,160 4,078,900 3,118,544 9,902,000 7,570,626

2005 21,403,200 16,363,928 1,250,900 956,382 3,796,900 2,902,940

2006 13,493,400 10,316,449 9,182,200 7,020,299 3,219,100 2,461,180

2007 17,550,700 13,418,479 6,361,200 4,863,489 1,952,800 1,493,023

2008 16,800,900 12,845,216 5,664,800 4,331,052 3,725,093 2,848,039

2009 7,618,900 5,825,070 16,295,000 12,458,427 10,351,223 7,914,082

2010 15,386,100 11,763,523 6,226,300 4,760,350 4,361,670 3,334,738

2011 15,613,143 11,937,110 3,502,600 2,677,931 3,749,570 2,866,753

2012 14,680,727 11,224,226 10,875,772 8,315,128 1,592,204 1,217,328

2013 3,669,836 2,805,792 4,452,299 3,404,028 3,473,019 2,655,315

Average 14,737,321 11,267,495 6,788,997 5,190,563 4,612,358 3,526,402

Source: U.S. Dept. of the Army, COE, 2015a.

The New Orleans District dredges an average annual 14.7 million yd3 (11.3 million m3). 

Current figures estimate that approximately 38 percent of that average is available for the beneficial 

use of dredge materials program (U.S. Dept. of the Army, COE, 2013). The remaining 62 percent of 

the total material dredged yearly by the COE’s New Orleans District is disposed of at placement 
3-168 Gulf of Mexico Multisale EIS

areas regulated under Section 404 of the Clean Water Act, at ODMDSs, or is stored in temporary 

staging areas located inland (e.g., the Pass a Loutre Hopper Dredge Disposal Site at the head of the 

Mississippi River’s main “birdfoot” distributary channel system).

Evaluation of dredged material for ocean disposal under the Marine Protection, Research, 

and Sanctuaries Act relies largely on biological (bioassay) tests. The ocean testing manual, 

commonly referred to as the Green Book (USEPA, 1991), provides national guidance for 

determining the suitability of dredged material for ocean disposal. Benthic and water-column 

impacts of dredged material disposal are evaluated prior to disposal through analysis of 

representative samples of the material to be disposed, unless the sand source is previously 

characterized. Sample evaluation may include physical analysis (i.e., grain size, total solids, and 

specific gravity) and chemical analysis for priority pollutants (i.e., metals, semivolatile and volatile 

organic compounds, PCBs, and pesticides).

BOEM anticipates that, over the next 70 years, the amount of dredged material disposed of 

at ODMDSs would fluctuate generally within the trends established by the COE district offices. 

Between 2004 and 2013, the New Orleans District has averaged about 14.7 million yd3

(11.2 million m3

) of material dredged per year disposed of at ODMDSs, while the Mobile District is 

about one-quarter of that quantity, or 4.6 million yd3 (3.5 million m3

). Quantities disposed of at 

ODMDSs may decrease as more beneficial uses of dredged material onshore are identified and 

evaluated.

3.3.2.3.6 Land-Based Discharges 

As authorized by the Clean Water Act, the NPDES permit program controls water pollution 

by regulating point sources on land that discharge pollutants into waters of the United States. Point 

sources are discrete conveyances (outfalls) such as pipes or manmade ditches that may contain 

process water flows and/or precipitation from impervious surfaces. Industrial, municipal, and other 

facilities must obtain permits if their discharges go directly to surface waters. In most cases, the 

NPDES permit program is administered by authorized states (USEPA, 2015a).

The NPDES program includes periodic characterization of outfall flow to limit pollutants 

entering surface water. The Mississippi River basin drains 41 percent of the 48 contiguous states of 

the United States. The basin covers more than 1,245,000 mi2 (3,224,535 km2

) and includes all or 

parts of 31 states and two Canadian provinces (U.S. Dept. of the Army, COE, 2015b). Nonpointsource contributions to the Mississippi River from erosion, uncontained runoff, and groundwater 

discharge are primary sources of freshwater, sediment, suspended solids, organic matter, and 

pollutants (including nutrients, heavy metals, pesticides, oil and grease, and pathogens). As a 

result, water quality in coastal waters of the northern GOM is highly influenced by seasonal variation 

in river flow. The Mississippi River introduces approximately 3,680,938 bbl of oil and grease per 

year from land-based sources (NRC, 2003, Table I-9, page 242; Chapter 3.3.2.4) into the waters of 

the Gulf. Nutrients carried in waters of the Louisiana and Texas rivers contribute to seasonal 
Impact-Producing Factors and Scenario 3-169

formation of hypoxic zones (1Chapter 3.3.3.12) on the Louisiana and Texas shelf. Additional 

information regarding water quality in the northern GOM can be found in Chapter 4.2. 

3.3.2.3.7 Trash and Debris 

Marine debris originates from both land-based and ocean-based sources. Forty-nine percent 

of marine debris originates from land-based sources, 18 percent originates from ocean-based 

sources, and 33 percent originates from general sources (sources that are a combination of landbased and sea-based activities) (USEPA, 2009a). Some of the sources of land-based marine debris 

are beachgoers, storm-water runoff, landfills, solid waste, rivers, floating structures, and illmaintained garbage bins. Marine debris also comes from combined sewer overflows and typically 

includes medical waste, street litter, and sewage. Ocean-based sources of marine debris include 

galley waste and other trash from ships, recreational boaters, fishermen, and offshore oil and gas 

exploration and production facilities. Commercial and recreational fishers produce trash and debris 

by discarding plastics (e.g., ropes, buoys, fishing line and nets, strapping bands, and sheeting), 

wood, and metal traps. Some trash items, such as glass, pieces of steel, and drums with chemical

or chemical residues, can be a health threat to local water supplies and as a result to biological, 

physical, and socioeconomic resources, to beachfront residents, and to users of recreational 

beaches. To compound this problem, there is population influx along the coastal shorelines. These 

factors, combined with the growing demand for manufactured and packaged goods, have led to an 

increase in nonbiodegradable solid wastes in our waterways.

3.3.2.4 Non-OCS Oil- and Gas-Related Spills

The NRC (2003) computed petroleum hydrocarbon inputs into North American marine 

waters for several major categories. The results show that three activities – extraction, 

transportation, and consumption – are the main sources of anthropogenic petroleum hydrocarbon 

pollution in the sea.

Non-OCS oil- and gas-related spills include the loss of petroleum products as a result of the 

extraction-, transportation-, and refinery-related activities from State oil and gas leases offshore 

Louisiana and Texas. The major sources of petroleum hydrocarbon discharges into the marine 

waters by transportation activities, including non-OCS oil- and gas-related sources, are tank vessel 

spills, operational discharges from cargo washings, coastal facilities spills, and gross atmospheric 

deposition of VOC releases from tankers. Non-OCS oil- and gas-related offshore spills are possible 

during the extensive maritime barging and tankering operations that occur in offshore waters of the 

GOM. Spills from transportation activities include a wide variety of petroleum products (not just 

crude oil), each of which behaves differently in the environment and may contain different 

concentrations of toxic compounds.

Consumption-related sources of petroleum releases to the marine environment include landbased sources (i.e., river discharge and runoff), two-stroke vessel discharge, non-tank vessel spills, 

operational discharges, gross atmospheric deposition, and aircraft dumping. Releases that occur 

during the consumption of petroleum, whether by individual car and boat owners, non-tank vessels, 
3-170 Gulf of Mexico Multisale EIS

or run-off from increasingly paved urban areas, contribute the vast majority of petroleum introduced 

to the environment through human activity. Nearly 85 percent of the 29 million gallons of petroleum 

that enter North American ocean waters each year as a result of human activities comes from landbased runoff, polluted rivers, and aircraft. Land runoff and two-stroke engines account for nearly 

three quarters of the petroleum introduced to North American waters from activities associated with 

petroleum consumption, activities almost exclusively restricted to coastal waters. Unlike other 

sources, inputs from consumption occur almost exclusively as slow chronic releases. The estimates 

for land-based sources of petroleum are the most poorly documented and the uncertainty associated 

with the estimates range over several orders of magnitude. On occasion, aircraft carry more fuel 

than they can safely land with so fuel is jettisoned into offshore marine waters. The amount of 

1,120 bbl (160 tonnes) of jettisoned fuel per year was estimated for the GOM.

Tables 3-27 and 3-28 provide the NRC (2003) estimates of hydrocarbon inputs into marine 

waters. In general, response activities to non-OCS oil- and gas-related spills would be similar to 

those described for an OCS oil- and gas-related spill (Chapter 3.2.7).

Table 3-27. Average Annual Inputs of Petroleum Hydrocarbons to Coastal Waters of the Gulf of 

Mexico, 1990-1999.

Inputs Western Gulf of Mexico Eastern Gulf of Mexico

(tonnes) (bbl) (tonnes) (bbl)

Extraction of Petroleum

Platforms Spills 90 630 trace1 trace

Atmospheric Releases (VOCs) trace trace trace trace

Permitted Produced-Water Discharges 590 4,130 trace trace

Sum of Extraction Inputs 680 4,760 trace trace

Transportation of Petroleum

Pipeline Spills 890 6,230 trace trace

Tank Vessel Spills 770 5,390 140 980

Coastal Facilities Spills2 740 5,180 10 70

Atmospheric Releases (VOCs)3 trace trace trace trace

Sum of Transportation Inputs4 2,400 16,800 160 1,120

Consumption of Petroleum

Land-Based Sources5 11,000 77,000 1,600 11,200

Recreational Vessels 770 5,390 770 5,390

Vessel >100 GT (spills) 100 700 30 210

Vessel >100 GT (operational discharges) trace trace trace trace

Vessel <100 GT (operational discharges) trace trace trace trace

Deposition of Atmospheric Releases 

(VOCs)

90 630 60 420

Aircraft Jettison of Fuel N/A N/A N/A N/A

Sum of Consumption 12,000 84,000 2,500 17,500
Impact-Producing Factors and Scenario 3-171

1

Trace indicates <70 bbl (10 tonnes). 2

Coastal facility spills do not include spills in coastal waters related to exploration and production 

spills or spills from vessels. The category “Coastal Facilities” includes aircraft, airport, refined 

product in coastal pipeline, industrial facilities, marinas, marine terminals, military facilities, 

municipal facilities, reception facilities, refineries, shipyards, and storage tanks. 3

Volatization of light hydrocarbons during tank vessel loading, washing, and voyage.

4

Sums may not match.

5

Inputs from land-based sources during consumption of petroleum are the sum of diverse sources. 

Three categories of wastewater discharge are summed: municipal; industrial (not related to 

petroleum refining); and petroleum refinery wastewater. Urban runoff is included. It results from 

oil droplets from vehicles washing into waterways from parking lots and roads, and the improper 

disposal of oil containing consumer products.

GT = gross tons.

N/A = not available.

VOCs = volatile organic compounds.

Source: NRC, 2003.

Table 3-28. Average Annual Inputs of Petroleum Hydrocarbons to Offshore Waters of the Gulf of 

Mexico, 1990-1999.

Inputs

Western Gulf of Mexico Eastern Gulf of Mexico

(tonnes) (bbl) (tonnes) (bbl)

Natural Sources

Seeps 70,000 490,000 70,000 490,000

Extraction of Petroleum

Platform Spills 50 350 trace1 trace

Atmospheric Releases (VOCs) 60 420 trace trace

Permitted Produced-Water Discharges 1,700 11,900 trace trace

Sum of Extraction 1,800 12,600 trace trace

Transportation of Petroleum

Pipelines Spills 60 420 trace trace

Tank Vessels Spills 1,500 10,500 10 70

Atmospheric Releases (VOCs) trace trace trace trace

Sum of Transportation 1,600 11,200 10 70

Consumption of Petroleum

Land-Based Consumption2 N/A N/A N/A N/A

Recreational Vessel Consumption3 N/A N/A N/A N/A

Vessel >100 GT (spill) 120 840 70 490

Vessel >100 GT (operational discharges) 25 175 trace trace

Vessel <100 GT (operational discharges) trace trace trace trace

Deposition of Atmospheric Releases 

(VOCs) 1,200 8,400 1,600 11,200

Aircraft Jettison of Fuel 80 560 80 560

Sum of Consumption4 1,400 9,800 1,800 12,600
3-172 Gulf of Mexico Multisale EIS

1

Trace indicates <70 bbl (10 tonnes).

2

Limited to coastal zone.

3

Limited to within 3 mi (5 km) of the coast.

4

Sums may not match.

GT = gross tons.

N/A = not available.

VOCs = volatile organic compounds.

Source: NRC, 2003.

3.3.2.5 Non-OCS Oil- and Gas- Related Air Emissions

There are many air emissions sources related to non-OCS oil- and gas-related activities. Air 

emissions are caused by non-OCS onshore oil and gas activities and offshore State oil and gas 

activities, including combustion sources from power and heat generation, and the use of 

compressors, pumps, and reciprocating engines (i.e., boilers, turbines, and other engines); 

emissions resulting from flaring and venting of gas; and fugitive emissions. For instance, at the 

northern border between Texas and Louisiana (Haynesville Shale), there is a very large reserve of 

recoverable natural gas with recent extensive leasing and exploration activities. The economic 

impact is important in the region; however, it also generates significant amounts of ozone precursors 

as revealed by air quality modeling scenarios ranging from limited, moderate, and aggressive 

development reported in Kemball-Cook et al. (2010). Such precursors, nitrogen oxides and VOCs, 

are emitted during drilling, subsequent rock fracturing, venting, well completion, dehydration of 

natural gas, and fugitive emissions from compressor engines, wells, and pipeline components. The 

principal pollutants from these air emissions could also include NOx, SOx, CO, PM10, PM2.5, H2S, 

VOC, benzene, ethylbenzene, toluene, xylene, glycols, and polycyclic aromatic hydrocarbons 

(PAHs).

Non-OCS oil- and gas-related activities can also include emissions from commercial and 

home heating, naturally occurring forest fires, motor vehicles, industrial activities in territorial seas 

and coastal waters, and industrial and transportation activities onshore. These activities can range 

from large, highly regulated industrialized sources such as electric utilities that burn fuel down to 

individual human sources such as outdoor grilling, jet skis, or using gasoline-powered equipment. In 

addition, sand borrowing and transportation in State territorial waters also generate emissions that 

can affect air quality. The principal pollutants from these air emissions sources include NOx, SOx, 

CO, PM10, PM2.5, and VOC. For more information on sources of air quality issues, refer to Chapter 

4.1.2. 

3.3.2.6 Other Non-OCS Oil- and Gas-Related Activities

3.3.2.6.1 Military Warning and Water Test Areas

The Gulf of Mexico (GOMEX) Range Complex contains four separate operating areas: 

Panama City and Pensacola, Florida; New Orleans, Louisiana, and Corpus Christi, Texas. The 

operating areas within the GOMEX Range Complex are not contiguous but are scattered throughout 

the GOM. The GOMEX Range Complex includes special-use airspace with associated warning 
Impact-Producing Factors and Scenario 3-173

areas and restricted airspace, and surface and subsurface sea space of the four operating areas. 

The air space over the GOM is used by the DOD for conducting various military operations. Twelve 

MWAs and six EWTAs are located within the GOM (Figure 2-7). These MWAs and EWTAs 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.

The WPA includes all or parts of the following military warning areas: W-147, W-228, and 

W-602. 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 (Figure 2-7).

To eliminate potential impacts from multiple-use conflicts on the aforementioned area and on 

blocks that the Navy has identified as needed for testing equipment and for training mine warfare 

personnel, a standard Military Areas Stipulation is routinely applied to all GOM leases 

(Appendix D.3).

In addition, BOEM’s Gulf of Mexico OCS Region issued NTL 2014-BOEM-G04, which 

provides links to the addresses and telephone numbers of the individual command headquarters for 

the military warning and water test areas in the GOM. The NTL 2014-BOEM-G04 can be found on 

BOEM’s website at http://www.boem.gov/Notices-to-Lessees-and-Operators/. 

Within the CPA, wholly or partially, lie six designated MWAs and three EWTAs that are used 

for military operations (Figure 2-7). The MWAs within the CPA total approximately 13.3 million ac or 

about 23 percent of the total acreage of the CPA. The EWTAs within the CPA total approximately 

7 million ac or about 12 percent of the total acreage of the CPA.

The EPA has 64,563,679 total acres; approximately 43,217,494 ac are in EWTAs and 

approximately 15,670,911 ac are in MWAs (Figure 2-7). The EWTAs and MWAs account for 

91 percent of the acreage within the EPA. The EPA portion of the proposed lease sale area is not 

within any of the MWAs; however, the entire EPA portion of the proposed lease sale area 

(657,905 ac) is within EWTA boundaries. In addition to the previously noted standard Military Areas 

Stipulation, blocks leased within the EWTAs will also be subject to the Evacuation Stipulation 

(Appendix D.4) and the Coordination Stipulation (Appendix D.5).

BOEM anticipates that, over the next 50 years, the military use areas currently designated 

regionwide would remain the same and that none of them would be released for nonmilitary use. 

Over the cumulative activities scenario, BOEM expects to continue to require military coordination 

stipulations in these areas. The intensity of the military’s use of these areas, or the type of activities 

conducted in them, is anticipated to fluctuate with military mission needs.
3-174 Gulf of Mexico Multisale EIS

3.3.2.6.2 Offshore Deepwater Ports and Nearshore Liquefied Natural Gas Terminals

Deepwater ports are designed to provide access for tankers and LNG carriers to offshore 

offloading facilities for hydrocarbon products, i.e., crude oil and natural gas. Crude oil passing 

through an offshore port may be temporarily stored and then transported to shore via pipeline. The 

term “deepwater port” includes all associated components and equipment, including pipelines, 

pumping stations, service platforms, mooring buoys, and similar features or equipment to the extent 

that they are located seaward of the high water mark (USDOT, MARAD, 2015b).

The Deepwater Port Act of 1974, as amended by the Maritime Transportation Security Act of 

2002, establishes a licensing system for ownership, construction, operation and decommissioning of 

deepwater port structures located beyond the U.S. territorial sea. The Deepwater Port Act sets out 

conditions that deepwater port license applicants must meet, including the minimization of adverse 

impacts on the marine environment and submission of detailed plans for construction, operation, and 

decommissioning of deepwater ports. The Deepwater Port Act also sets out detailed procedures for 

the issuance of licenses by the Secretary of Transportation and prohibits the issuance of a license 

without the approval of the Governors of the adjacent coastal states (USDOT, MARAD, 2015b). 

Since early 2015, 20 deepwater port license applications have been filed with the Maritime 

Administration (MARAD) for approval (18 applications for licenses to import LNG and 2 applications 

filed for licenses to import oil).

Gulf of Mexico Offshore Deepwater Ports

Currently in the U.S., there is one offshore deepwater port in operation in the GOM, i.e., the 

Louisiana Offshore Oil Port (LOOP). The LOOP has received and transferred over 11 Bbbl of crude 

oil since its inception (LOOP, LLC, 2015).The offloaded crude oil is transported to shore via 48-in 

(123-cm) diameter pipeline. The LOOP receives and temporarily stores crude oil supplies from three 

sources, including the following:

• tankers carrying foreign (imported oil from Arabian Gulf, Russia, West Africa, 

North Sea, Mexico, and South America) and domestic crude oil from FPSOs; 

• domestic crude oil produced in the Gulf of Mexico (Mars and Thunder Horse 

platforms); and 

• movement of domestic crude oil via the Houston to Houma (Ho-Ho) pipeline.

Another LNG deepwater port (Port Dolphin) has been proposed in the Gulf of Mexico, and it 

has been approved by MARAD and the USCG. Port Dolphin is in development and is obtaining the 

necessary permits for construction; in addition, Höegh LNG is currently evaluating the market 

potential that may affect the status of the project (Castro, official communication, 2015). Port 

Dolphin has approval from the Federal Energy Regulatory Commission (FERC) and MARAD for 

completion of construction of the deepwater port and pipeline until December 2018.Gulf Gateway 

Energy Bridge was an LNG deepwater port in the Gulf of Mexico, and it was decommissioned in 
Impact-Producing Factors and Scenario 3-175

2013. Additional information on the licenses and applications of deepwater ports and LNG facilities 

specific to the Gulf of Mexico can be found on MARAD’s website (USDOT, MARAD, 2015).

In 2015, Delfin LNG proposed an offshore floating LNG project in the U.S. which would be 

located approximately 45 mi (72 km) offshore of Cameron, Louisiana Federal Register (2015c). The 

proposed project schedule is to receive Federal approvals and the Deepwater Port Act license in 

2016, to have offshore and onshore construction in 2017 to 2018, and to commence operations in 

2019.

Gulf Gateway Energy Bridge, LLC (Gulf Gateway) operated in the Gulf of Mexico off the 

coast of Louisiana from 2005 to 2012. The decision to decommission the facility was due to 

irreparable hurricane damage to pipelines (Hurricane Ike in 2008) interconnecting with the 

deepwater port and a changing natural gas market, which impacted the operator’s ability to receive 

consistent shipments (USDOT, MARAD, 2015b).

Nearshore Liquefied Natural Gas (LNG)

The FERC is responsible for authorizing the siting and construction of onshore and 

nearshore (State waters) LNG import or export facilities under Section 3 of the Natural Gas Act. The 

FERC, under Section 7 of the Natural Gas Act, also issues certificates of public convenience and 

necessity for LNG facilities engaged in interstate natural gas transportation by pipeline. There are 

more than 110 LNG facilities operating in the U.S. performing a variety of services. The LNG 

terminal means all natural gas facilities located onshore or nearshore (in State waters) that are used 

to receive, unload, load, store, transport, gasify, liquefy, or process natural gas that is 

• imported to the U.S. from a foreign country, 

• exported to a foreign country from the U.S., or 

• transported in interstate commerce by a waterborne vessel.

Some facilities export natural gas from the U.S., some provide natural gas supply to the 

interstate pipeline system or local distribution companies, while others are used to store natural gas 

for periods of peak demand. There are also facilities that produce LNG for vehicle fuel or for 

industrial use. Depending on location and use, an LNG facility may be regulated by several Federal 

agencies and by State utility regulatory agencies. Projects that are approved and built are subject to 

FERC’s oversight for as long as the facility is in operation. The FERC currently regulates 

24 operational LNG facilities (USDOE, FERC, 2015b). In the Gulf of Mexico State waters 

(nearshore), there are currently five LNG terminals, of which all five are currently in operation and 

planned for expansion of the facilities to export of natural gas to foreign markets:

• Freeport LNG Import/Export Terminal (Freeport, Texas);

• Golden Pass LNG Import/Export Terminal (Sabine Pass, Texas);
3-176 Gulf of Mexico Multisale EIS

• Sabine Pass LNG Import/Export Terminal (Sabine Pass, Texas);

• Cameron LNG Import/Export Terminal (Formerly Hackberry LNG) (Cameron, 

Louisiana); and

• Lake Charles LNG Import/Export Terminal (Lake Charles, Louisiana).

The Corpus Christi LNG import/export terminal (Corpus Christi, Texas) was recently 

reviewed and approved by FERC and DOE, and they subsequently began construction in May 2015 

(Cheniere Energy, 2015).

While interest in deepwater port development peaked in the 2000-2010 period, economic 

conditions for LNG have changed since 2010. BOEM notes that interest in LNG offshore terminal 

projects is expected to diminish over at least the next decade, with potential and subsequent 

stabilization in the LNG market. It is possible that LNG facilities in the Gulf of Mexico, or elsewhere, 

presently in the permitting process or in early construction phases could be withdrawn from 

consideration, cancelled, or deferred until LNG economics improve or until facilities under 

construction for importing LNG could be modified for exporting LNG. BOEM anticipates that, over 

the next 50 years, two additional LNG facilities in the CPA would be licensed and operating. It is 

unclear as to whether these LNG facilities will occur during the period of a proposed action, although 

trends evident in the submittal, approval, and withdrawal of recent applications suggest that such 

development is unlikely. Additional information on LNG terminal applications, application review 

determinations, and operational status for the Gulf of Mexico offshore LNG facilities can be found on 

MARAD’s website at http://www.marad.dot.gov/ports/.

3.3.2.6.3 Development of Gas Hydrates

Methane hydrates (or gas hydrates) are cage-like lattices of water molecules containing 

methane, the chief constituent of natural gas found under arctic permafrost, as well as beneath the 

ocean floor. These may represent one of the world's largest reservoirs of carbon-based fuel. 

However, with abundant availability of natural gas from conventional and shale resources, there is 

no economic incentive to develop gas hydrate resources, and no commercial-scale technologies to 

exploit them have been demonstrated (USDOE, Energy Information Administration, 2012).

In the Gulf of Mexico, a Joint Industry Project was formed to carry out an assessment of gas 

hydrates in deep water of the GOM and to better understand the impact of hydrates on safety and 

seafloor stability, climate change, and assessment of the feasibility of marine hydrate as a potential 

future energy source. The findings of the 13-year (2001-2014) study concluded that hydrates are a 

readily managed, shallow drilling hazard and that hazard mitigation can be accomplished using 

existing protocols; field data indicate the occurrence of high-saturation hydrate accumulations in the 

GOM; methods employed to locate and predict hydrates were effective and accurate; and 

development of prototype tools and methods to collect hydrate pressure cores were developed.
Impact-Producing Factors and Scenario 3-177

BOEM released the results of a systematic geological and statistical assessment of gas 

hydrates resources in the GOM (USDOI, MMS, 2008a). This assessment incorporates the latest 

science with regard to the geological and geochemical controls on gas hydrate occurrence. It 

indicated that a mean volume of 607 trillion m3 (21,444 Tcf) of methane was in-place in hydrate form. 

The assessment has determined that a mean of 190 trillion m3 (6,710 Tcf) of this resource occurs as 

relatively high-concentration accumulations within sand reservoirs that may someday be produced. 

The remainder occurs within clay-dominated sediments from which methane probably would never 

be economically or technically recoverable.

BOEM anticipates that, over the next 40 years, the Joint Industry Project would complete the 

third leg of its characterization project for GOM gas hydrates in the cumulative impacts area. Within 

40 years, it is likely that the first U.S. domestic production from hydrates may occur in Alaska, where 

gas obtained from onshore hydrates would 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, it is not possible to discount the possibility that first U.S. domestic production of gas 

hydrates could occur in the GOM (Moridis et al., 2008). Despite the substantially increased 

complexity and cost of offshore operations, there is a mature network of available pipeline capacity 

and easier access to markets in the GOM.

3.3.2.6.4 Renewable Energy and Alternative Use

On August 8, 2005, President George W. Bush signed the Energy Policy Act of 2005 into 

law. Section 388 (a) of the Energy Policy Act amended Section 8 of the OCSLA (43 U.S.C. § 1337) 

to authorize DOI to grant leases, easements, or rights-of-way on the OCS for the development and 

support of energy resources other than oil and gas and to allow for alternate uses of existing 

structures on OCS lands.

A final programmatic EIS for the OCS renewable energy program was published by this 

Agency in October 2007 (USDOI, MMS, 2007a) and a Record of Decision was published in the 

Federal Register on January 10, 2008 (Federal Register, 2008). The Act authorized this Agency to 

develop a comprehensive program and regulations to implement the new authority. Final rules for 

BOEM’s renewable energy program were published on April 29, 2009, as 30 CFR part 285 (Federal 

Register, 2009).

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. The 

first and most technologically mature renewable energy is wind energy, a popular source of clean 

and renewable energy that has been in use for centuries. The DOE released a strategic plan for 

creating an offshore wind industry in the U.S. (USDOE, 2011). In this plan, DOE determined that 

offshore wind energy can help the Nation reduce its greenhouse gas emissions, diversify its energy 

supply, provide cost-competitive electricity to key coastal regions, and stimulate economic 

revitalization of key sectors of the economy. However, if the Nation is to realize these benefits, key 

barriers to the development and deployment of offshore wind technology must be overcome, 
3-178 Gulf of Mexico Multisale EIS

including the relatively high cost of energy, technical challenges surrounding installation and grid 

interconnection, and the permitting processes governing deployment in both Federal and State 

waters. There are two critical objectives to realize the strategic plan’s goals: (1) reduce the cost of 

offshore wind energy; and (2) reduce the timeline for deploying offshore wind energy (USDOE, 2011, 

page 2). Since April 29, 2009, when the regulations governing renewable energy on the OCS were 

publicized, no wind park developments have been proposed in OCS waters of the GOM; however, 

there have been proposals in Texas coastal waters.

In Fiscal Year 2010, the DOE instituted the Offshore Wind Innovation and Demonstration 

initiative to consolidate and expand its efforts to promote and accelerate responsible commercial 

offshore wind development in the United States. In 2012, the DOE’s Wind Program announced 

Federal funding nationwide in three major categories: technology development; market acceleration; 

and advanced technology demonstration. The Wind Program is working with BOEM to advance a 

national strategy for offshore wind research and development (Navigant Consulting, Inc., 2013). 

According to the Navigant Consulting, Inc. report, there is a potential of 594 gigawatts of potential 

wind energy available in the GOM. Offshore wind could create approximately 20.7 direct jobs per 

annual megawatt (or 20,700 jobs per annual gigawatt) installed in U.S. waters. Baryonyx Rio 

Grande Wind Farms received $4 million to produce three demonstration turbines in State waters 

(refer to “Renewable Energy Projects in Texas State Waters” below).

The second category of potential offshore renewable energy technologies is marine 

hydrokinetic systems, which are in a more developmental stage relative to wind turbines. The 

marine hydrokinetic systems consist of devices capable of capturing energy from ocean waves and 

currents. There has been no interest expressed in wave or current technologies in the GOM 

because the conditions necessary for their deployment are not suitable to the Gulf of Mexico. The 

marine hydrokinetic current technologies are actively being considered for the east coast of Florida 

where the Gulf Stream would provide a strong and continuous source of energy to turn underwater 

turbines.

The Energy Policy Act clarifies the Secretary’s authority to allow the existing oil and gas 

structures on OCS lands to remain in place after production activities have ceased and to transfer 

liability and extend the life of these facilities for non-oil and gas purposes, such as research, 

renewable energy production, aquaculture, etc., before being removed. With many bottom-founded 

platform structures located along the nearshore border of OCS waters, the GOM would seem to 

have some potential for the reuse of these facilities.

BOEM expects that, over the next 40 years, a limited number of alternative use projects 

would be proposed in the WPA. It is also likely that these alternative use projects would 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.
Impact-Producing Factors and Scenario 3-179

Renewable Energy Projects in Texas State Waters

On October 24, 2005, the Texas General Land Office announced authorization for the first 

offshore wind energy project in the United States to be built in State waters off the Texas coast. An 

11,355-ac (4,595-ha) lease was awarded to Galveston-Offshore Wind, L.L.C., a subsidiary of 

Louisiana-based Wind Energy Systems Technologies (now Coastal Point Energy LLC), where 

50 wind turbines would be placed for the 150-megawatt development. The lease area is located 

approximately 7 mi (11 km) southeast of Galveston Island. Wind Energy Systems Technologies 

(now Coastal Point Energy LLC) was awarded the rights for additional leases south of the 

Galveston-Offshore Wind, L.L.C. project area, which would be developed after the Galveston 

project. The Texas General Land Office leased acreage to Baryonyx Corporation to build two 

offshore wind projects. While Baryonyx Corporation received money during the first phase of the 

Offshore Wind and Innovation Demonstration initiative, they did not receive funding to continue into 

the second phase (USDOE, Office of Energy Efficiency and Renewable Energy, 2015). 

Approximately 26,201 ac (10,603 ha) were leased off Nueces County, Texas, for the Mustang 

Project and about 40,000 ac (16,187 ha) were leased for the Rio Grande Project off South Padre 

Island. Both projects range from 5 to 10 mi (8 to 16 km) offshore. Below are the statuses of the 

reported projects:

Project Name

Proposed 

Capacity 

(megawatts)

Number 

of Turbines Status Notes

Target 

Completion 

Date

Galveston Offshore 

Wind (Coastal Point 

Energy)

150 55-75

Received lease from Texas General 

Land Office in 2007. Announced 

intention to install a 750-kilowatt test 

turbine.

2018

Baryonyx Rio Grande 

Wind Farms (North 

and South)

1,000 100-200

Received lease from Texas General 

Land Office in 2009. The COE’s 

environmental studies are underway. 

Received the DOE Wind Program grant 

to produce 3 demonstration turbines by 

2017.

2019

3.3.2.6.5 Aquaculture

Offshore aquaculture is the rearing of aquatic animals in controlled environments (e.g., 

cages or net pens) in Federal waters. The NOAA has published the rule to implement a Fishery 

Management Plan for regulating offshore aquaculture in the Gulf of Mexico (Federal Register, 2016). 

The rule establishes a comprehensive regulatory program for managing the development of an 

aquaculture industry in Federal waters of the Gulf of Mexico. An interagency group has been 

established and is working on the permitting process for future proposed aquaculture activities. This 

group consists of the three permitting agencies, i.e., NOAA, USEPA, and USACE, and other 

agencies with an interest or expertise on the OCS, including USCG, FWS, BOEM, and BSEE. This 

group will continue to coordinate the permitting process.
3-180 Gulf of Mexico Multisale EIS

3.3.2.6.6 OCS Sand Borrowing

If OCS sand is desired for coastal restoration or beach nourishment, BOEM uses the 

following two types of lease conveyances: a noncompetitive negotiated agreement (NNA) that can 

only be used for obtaining sand and gravel for public works projects funded in part or whole by a 

Federal, State, or local government agency; and a competitive lease sale in which any qualified 

person may submit a bid. BOEM has issued 48 noncompetitive negotiated agreements but has 

never had 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.

Since 2003, BOEM has participated in the multiagency Louisiana Sand Management 

Working Group to identify, prioritize, and define a pathway for accessing sand resources in the nearoffshore OCS of Louisiana, an area where competitive space use mainly involves OCS oil- and gasrelated infrastructure such as wells, platforms, and pipelines. Table 3-29 shows the projected 

approximate volume of OCS sand uses for coastal restoration projects over the next 5 years. 

Approximately 76 million yd3 (58 million m3

) are expected to be needed for coastal restoration 

projects, as reported by the Gulf of Mexico OCS Region’s Marine Minerals Program. To visualize 

such a dimension, this volume of sand could fill the Louisiana Superdome stadium 16.5 times.

Table 3-29. Projected OCS Sand Resource Needs for Planned Restoration Projects.

Restoration Project Maximum Sand 

(yd3)

OCS Lease Area and Block Number

(if known)

NRDA Breton Island ~6,000,000 Breton Sound 42-44; Main Pass 42-44, 53-55

NRDA Caillou Lake Headlands 

(Whiskey) 13,400,000 Ship Shoal 88

Mississippi Coastal 

Improvement Program (MsCIP) 23,000,000 Mobile 817-819, 861-864

Southwest Louisiana ~15,000,000 N/A

Raccoon Island ~1,100,000 Ship Shoal 88 and 89; South Pelto 12-14

Trinity and East Islands ~16,260,000 Ship Shoal 88 and 89; South Pelto 12-14

Timbalier Island ~10,700,000 Ship Shoal 88 and 89; South Pelto 12-14

East Timbalier Island 

Restoration ~11,230,000 South Pelto 12-14

Caminada Headland (I and II) ~11,300,000 South Pelto 12-14

Total ~108,490,000

N/A = not available.

~ = approximately.

In 2005, BOEM began to conduct offshore sand studies to investigate available sources of 

OCS sand for restoring coastal areas in Louisiana, Texas, Alabama, and Mississippi that were 

damaged by Hurricanes Katrina and Rita. Sand sources identified through BOEM’s cooperative 

effort with Louisiana would likely serve as the major source of material for the restoration of the 
Impact-Producing Factors and Scenario 3-181

barrier islands planned as part of the Louisiana Coastal Area ecosystem restoration study (U.S. 

Dept. of the Army, COE, 2004) and for projects identified in the Louisiana 2012 and 2017 Master 

Plans (State of Louisiana, Coastal Protection and Restoration Authority, 2012 and 2015), projects 

developed under the Deepwater Horizon Natural Resource Damage Assessment (NRDA); Coastal 

Wetlands Planning, Protection and Restoration Act; Coastal Impact Assessment Program; National 

Fish and Wildlife Foundation’s Gulf Environmental Benefit Fund; and the 2012 Resources and 

Ecosystems Sustainability, Tourist Opportunities and Revived Economies of the Gulf Coast States 

Act (RESTORE Act) barrier island restoration efforts.

Since the dredging of OCS sand and the associated activities of oceangoing dredge vessels 

could present some use conflicts on blocks also leased for oil and gas extraction, BOEM initiated a 

regional offshore sand management program in Louisiana in 2003, which, over the course of 

10 years and several meetings, has developed options and recommendations for an orderly process 

to manage the competing use of OCS sand resources in areas of existing OCS infrastructure. With 

input from the Sand Management Working Group, BOEM has developed guidelines for sand 

resource allocations, maintaining a master schedule of potential sand dredging projects, developing 

procedures for accessing sand under emergency conditions, and establishing environmental 

requirements for the use of offshore borrow areas.

Noncompetitive negotiated agreements have been issued in the following locations. No 

sand noncompetitive negotiated agreements have ever been issued for OCS sand in the WPA. The 

EPA has three noncompetitive negotiated agreements:

• Pinellas County, Florida; 

• Longboat Key, Town of Longboat Key, Florida; and 

• Collier County, Florida.

The following 11 noncompetitive negotiated agreements for OCS sand have been issued in 

the CPA:

• Holly Beach, Cameron Parish, Louisiana; 

• South Pelto test area, Terrebonne Parish, Louisiana; 

• Pelican Island shoreline restoration, Plaquemines Parish, Louisiana; 

• Raccoon Island marsh creation, Terrebonne Parish, Louisiana; 

• St. Bernard Shoals, St. Bernard and Plaquemines Parishes, Louisiana; 

• Ship Shoal in South Pelto Area for Caminada Headland restoration, Lafourche 

and Jefferson Parishes, Louisiana; 

• Sabine Bank, Cameron Parish, Louisiana; 
3-182 Gulf of Mexico Multisale EIS

• Caminada II, Lafourche and Jefferson Parishes, Louisiana; 

• NRDA Whiskey Island, Terrebonne Parish, Louisiana; 

• North Breton Island, Breton Island National Wildlife Refuge, Louisiana; and

• Mississippi Coastal Improvements Program, Gulf Island National Seashore, 

Mississippi.

In 2013, BOEM began working with the U.S. Dept. of the Interior, Geological Survey (USGS) 

and FWS on a North Breton Island Restoration Project work plan, which is included in the NRDA 

early restoration plan, Phase III (USDOC, NOAA, 2015c). The North Breton Island Restoration 

Project (Louisiana) would use sand from the Breton Sound Area to restore shorebird and brown 

pelican nesting habitat in the Breton National Wildlife Refuge. It is anticipated that the 

noncompetitive negotiated agreement would be signed in 2016, with dredging for the North Breton 

Island Restoration Project beginning in late 2017. BOEM issued two noncompetitive negotiated 

agreements in Louisiana in 2015: the first was for the Deepwater Horizon NRDA Whiskey Island 

Restoration Project in Terrebonne Parish using sand from Ship Shoal Block 88; and the second was 

for Phase Two of the Caminada Headland Restoration Project in Lafourche and Jefferson Parishes 

using sand from South Pelto Blocks 13 and 14. Dredging for these projects began in 2015 and is 

anticipated to be complete in 2017. Another project site, East Timbalier Island, has been severely 

degraded due to the impacts of several strong storms, subsidence, and other factors. Historically, 

the island served to define the seaward boundary of the eastern Terrebonne Basin estuary, reducing 

the transmission of GOM waves into Terrebonne Bay. The noncompetitive negotiated agreement is 

expected to be signed in 2017 using proposed borrow areas from Ship Shoal in South Pelto Blocks 

12, 13, and 14. BOEM is also working with the COE’s Mobile District and the National Park Service 

on the Mississippi Coastal Improvements Program, which would use OCS sand from the Mobile 

Area for barrier island restoration projects along East and West Ship Islands in the Gulf Islands 

National Seashore. The noncompetitive negotiated agreement Record of Decision was signed in 

2015 and will utilize OCS sand from Mobile Blocks 817-819 and 861-864. Dredging associated with 

the Mississippi Coastal Improvements Program is expected to begin in late 2016 and is expected to 

continue until 2018.

BOEM is authorized by 30 CFR § 550.101 to ensure that operations conform to sound 

conservation practice to preserve, protect, and develop mineral resources of the OCS and to 

minimize or eliminate conflicts between the exploration, development, and production of oil and 

natural gas and the recovery of other resources. BOEM’s responsibility as steward of significant 

sand resources on the OCS is outlined in NTL 2009-G04. This NTL 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. The use of OCS sediment resources is 

authorized by BOEM through its Marine Minerals Program. Additional measures have been 

implemented and continue to be developed to help safeguard the most significant OCS sediment 

resources, reduce multiple use conflicts, and minimize interference with oil and gas operations under 

existing leases or pipeline rights-of-way. Mitigating measures ensure activities (including surface or 
Impact-Producing Factors and Scenario 3-183

near-surface emplacement of platforms, wells, drilling rigs, pipelines, umbilicals, and cables) avoid or 

are removed from, to the maximum extent practicable, significant OCS sediment resources.

Over the next 50 years, increased use of OCS sand for restoration projects in states that fall 

within the CPA are likely. Currently, no WPA restoration projects have been specifically identified. 

The boundary between the OCS and Texas State waters (9 nmi [10 mi; 16 km]) allows that some 

offshore sand is within the jurisdiction of the State; however, the easternmost portion of the shelf in 

Texas State waters is relatively devoid of beach-quality sand deposits. The Texas General Land 

Office, in cooperation with BOEM and the Texas Bureau of Economic Geology, has investigated the 

potential for use of Heald and Sabine Banks and confirmed substantial reserves of restoration 

quality sand. However, the State of Texas has yet to identify specific projects. The COE has 

intermittently used OCS sand reserves, and it is expected that this trend would continue. With 

respect to Louisiana, some uncertainty exists as to the amount of offshore OCS sand that would 

eventually be sought for coastal restoration projects. The Louisiana Coastal Area Ecosystem 

Restoration Plan potentially may use up to 60 million yd3 (46 million m3

) (U.S. Dept. of the Army, 

COE, 2009a). Recently, there has been an increase in requests from Louisiana for State-funded 

OCS sand resources projects. BOEM anticipates that this growing trend of State-led projects would 

continue into the future as restoration funding is made available directly to the State through the 

Coastal Impact Assistance Program, the Gulf of Mexico RESTORE Act, Coastal Wetlands Planning, 

Protection and Restoration Act, National Fish and Wildlife Foundation: Gulf Environmental Benefit 

Fund, the Deepwater Horizon NRDA restoration, and GOMESA. These programs are outlined in 

more detail in Chapter 3.3.2.8.3. 

3.3.2.7 Noise from Non-OCS Oil- and Gas-Related Sources

Other noise sources in the GOM are from non-OCS oil- and gas-related activities: vessel 

propeller cavitation from commercial shipping vessels, research vessels, tourism vessels, and 

commercial and recreational fishing vessels; sources from other equipment used on vessels (e.g., 

pingers used in fisheries to prevent animals getting caught in nets); State drilling operations; aircraft; 

military operations; coastal infrastructure construction (e.g., pile driving); underwater explosions; and 

natural phenomena such as wind, large storms, or lightning strikes. It is not under BOEM’s authority 

to regulate any of these non-OCS oil- and gas-related noise sources, although some do occur on the 

OCS. Noise related to non-OCS oil- and gas-related G&G activities can be found in Chapter 

3.3.2.2.5 above. Refer to Chapter 3.1.9 for general information on OCS oil- and gas-related 

sources of noise in the GOM.

Non-OCS Oil- and Gas-Related Geological and Geophysical Surveys

The G&G surveys are conducted to (1) obtain data for hydrocarbon and mineral exploration 

and production in Federal or State waters; (2) aid in siting renewable energy structures and facilities, 

and pipelines; (3) locate and monitor the use of potential sand and gravel resources for 

development; (4) identify possible seafloor or shallow-depth geologic hazards; and (5) locate 

potential archaeological resources and benthic habitats that should be avoided (Chapters 4.4 and 

4.13, Deepwater Benthic Communities and Archaeological Resources, respectively).
3-184 Gulf of Mexico Multisale EIS

Detailed descriptions of G&G activities are provided in more detail in the Atlantic G&G 

Activities Programmatic EIS (USDOI, BOEM, 2014a). A Programmatic EIS is currently being 

developed for the GOM (refer to Chapter 1.7). The selection of a specific technique or suite of 

techniques is driven by data needs and the target of interest. These activities include the following:

• various types of deep-penetration seismic airgun surveys used for State oil and 

gas exploration and development;

• other types of surveys and sampling activities used only in support of State oil 

and gas exploration and development, including electromagnetic surveys, deep 

stratigraphic and shallow test drilling, and various remote-sensing methods;

• HRG surveys used in all three program areas to detect shallow geohazards and 

marine minerals, archaeological resources, and certain types of benthic 

communities; and

• geological and geotechnical bottom sampling used in all three program areas to 

assess the suitability of seafloor sediments for supporting structures (e.g., 

platforms, pipelines, cables, renewable energy facilities such as wind turbines) or 

to evaluate the quantity and quality of marine minerals and sand for beach 

nourishment or other potential marine mineral extraction projects.

Deep-penetration seismic surveys, in which survey vessels tow an airgun or an array of 

airguns that emit acoustic energy pulses through the overlying water then into the seafloor over long 

durations and over large areas, are the most extensive G&G activities that would be conducted. 

These surveys would occur almost exclusively in support of oil and gas exploration and development 

and could be conducted in State waters. The G&G activities in support of renewable energy 

development would consist mainly of HRG and geotechnical surveys in Federal and State waters 

less than 40 m (131 ft) deep (USDOI, MMS, 2007a); this area represents approximately 25.9 percent 

of the GOM. The G&G activities in support of marine mineral uses (e.g., sand and gravel mining) 

would consist mainly of HRG and geotechnical surveys in Federal and State waters greater than 

30 m (98 ft) deep; this area represents approximately 19.5 percent of the GOM. The G&G activities 

beyond the outer boundary of the planning areas have not been determined but could include 

geophysical surveys in support of the U.S. Extended Continental Shelf Project, which aims to 

establish the full extent of the continental shelf of the U.S., consistent with international law.

3.3.2.8 Coastal Environments

3.3.2.8.1 Sea-Level Rise and Subsidence

As part of the Mississippi River’s delta system, both the Delta Plain and the Chenier Plain of 

the Louisiana Coastal Area (LCA) are experiencing relatively high rates of subsidence. All 

coastlines of the world have been experiencing a gradual absolute rise of sea level that is based on 

measurements across the globe and that extends across the influence of a single sedimentary 

basin. There are two aspects of sea-level rise during the past 10,000 years (Holocene Epoch): 
Impact-Producing Factors and Scenario 3-185

Although absolute sea-level rise is a 

contributor to the total amount of sea-level 

rise along the Gulf Coast, subsidence is 

the most important contributor to the total. 

absolute sea-level rise and relative sea-level rise. Absolute sea-level rise refers to a net increase in 

the volume of water in the world’s oceans. Relative sea-level rise refers to the appearance of sealevel rise, a circumstance where subsidence of the land is taking place at the same time that an 

absolute sea-level change may be occurring. Geologists tend to consider all sea-level rises as 

relative because the influence of one or the other is difficult to separate over geologic timeframes.

An absolute sea-level rise would be caused by the following two main contributors to the 

volume of ocean water on the Earth’s surface: (1) change in the volume of ocean water based on 

temperature; and (2) change in the amount of ice locked in glaciers, mountain ice caps, and the 

polar ice sheets. For the period 1961-2003, thermal expansion of the oceans accounts for only 

23 ± 9 percent of the observed rate of sea-level rise (Bindoff et al., 2007); the remainder is water 

added to the oceans by melting glaciers, ice caps, and the polar ice sheets. The measurement of 

sea-level rise over the last century is based on tidal gauges and, more recently, satellite 

observations, which are not model dependent. Projections for future sea-level rise are dependent on 

temperature. As determined by an analysis of air bubbles trapped in Antarctic ice cores, today’s 

atmospheric concentration of CO2 is the highest it has ever been over the last 2.1 million years (Karl 

et al., 2009; Luthi et al., 2008; Hönisch et al., 2009). Although the measured data for atmospheric 

CO2 concentration or temperatures measurements since the Industrial Revolution are generally not 

in dispute, proxy data for climates of the geologic past are a source of debate, and the models 

constructed to make projections for how climate may change remain controversial. Climate models 

are very sophisticated, but they may not account for all variables that are important or may not 

assign variables the weight of their true influence.

The Intergovernmental Panel on Climate 

Change (IPCC) reported that, since 1961, global 

average sea level (mean sea level) has risen at an 

average rate of 1.8 millimeter/year (mm/yr) 

(0.07 in/yr) and, since 1993, at 3.1 mm/yr 

(0.12 in/yr) (Bindoff et al., 2007). With updated 

satellite data to 2010, Church and White (2011) show that satellite-measured sea levels continue to 

rise at a rate close to that of the upper range of the IPCC projections (IPCC, 2012). It is unclear 

whether the faster rate for 1993-2010 reflects decadal variability or an increase in the longer-term 

trend. In the structured context used by the IPCC, there is high confidence that the observed sealevel rise rate increased from the 19th to the 20th century. Over the period 1901 to 2010, global 

mean sea level rose by 0.19 m (0.62 ft) (with a range of 0.17-0.21 m [56-69 ft]). The rate of sealevel rise since the mid-19th century has been larger than the mean rate during the previous two 

millennia (IPCC, 2014). The U.S. Global Change Research Program reported that, over the last 

50 years, sea level has risen up to 8 in (203 mm) along parts of the Atlantic and Gulf Coasts, which 

included Louisiana and Texas (Karl et al., 2009), and that global sea level is currently rising at an 

increasing rate.

In comparison to other areas along the Gulf Coast, Louisiana’s Mississippi Delta and Chenier 

Plains are built of young sediments deposited over the last 7,000 years. These deltaic sediments 
3-186 Gulf of Mexico Multisale EIS

have been undergoing compaction and subsidence since they were deposited. The land is sinking 

at the same time that sea level is rising, contributing to high rates of relative sea-level rise along the 

Louisiana coast. Blum and Roberts (2009) posited four scenarios for subsidence and sea-level rise, 

and they concluded sediment starvation alone would cause approximately 2,286 mi2 (592,071 ha) of 

the modern delta plain to submerge by 2100, without any other impacting factors (including sea-level 

rise) contributing to land loss.

A general value of approximately 6 mm/yr (0.23 in/yr) of subsidence from sediment 

compaction, dewatering, and oxidation of organic matter (Meckel et al., 2006; Dokka, 2006) is a 

reasonable rate to attribute to the Louisiana coastal area, with the understanding that subsidence 

rates along the Louisiana coast are spatially variable and influenced by subsurface structure and the 

timing and manner that the delta was deposited. 

Stephens (2009 and 2010) reported that the influence of subsurface structure has not been 

taken into account in subsidence assessments in the LCA and along the Gulf Coast (Stephens, 

2009, page 747). Most workers studying the effects of subsidence along the LCA have focused on 

surficial or near-surface geologic data sources and have made no attempt to integrate basin analysis 

into planning for coastal restoration or flood control project planning.

Results from the National Assessment of Coastal Vulnerability to Sea Level Rise estimate 

the rate of sea-level rise in the GOM, in particular the areas around Eugene Island, Louisiana, to be 

the highest (9.65 mm/yr; 3.17 ft/century) in the United States (USDOC, NOAA, 2015d). This 

classification is based upon variables such as coastal geomorphology, regional coastal slope, rate of 

sea-level rise, wave and tide characteristics, and historical shoreline change rates. As much as 

88 percent of the northern GOM falls within the high vulnerability category. Areas ranked as the very 

low vulnerability category still have some sea-level rise. The lowest rate of rise is found in Panama 

City, Florida, with a rate of 1.6 mm/yr or 0.53 ft/century. Given this range, BOEM anticipates that, 

over the next 50 years, the northern GOM would likely experience a minimum relative sea-level rise 

of 80.7 mm (3.18 in) and a maximum relative sea-level rise of 482.6 mm (19.0 in). Sea-level rise 

and subsidence together have the potential to affect many important areas, including the OCS oil 

and gas industry, waterborne commerce, commercial fishery landings, and important habitat for 

biological resources (State of Louisiana, Coastal Protection and Restoration Authority, 2012a. Oil 

and gas infrastructure located within 15 in (381 mm) of the highest high tide in coastal areas along 

the Gulf of Mexico could potentially be affected by sea-level rise during this program. Programmatic 

aspects of climate change relative to the environmental baseline for the GOM are discussed in 

Chapter 4.2.1 of the Five-Year Program EIS.

Formation Extraction and Subsidence

Extracting fluids and gas from geologic formations can lead to localized subsidence at the 

surface. The Texas coast is experiencing high (5-11 mm/yr) (0.19-0.43 in) rates of relative sea-level 

rise that are the sum of subsidence and eustatic sea-level rise (Sharp and Hill, 1995). Even higher 

rates are associated with areas of groundwater pumping from confined aquifers. Berman (2005, 
Impact-Producing Factors and Scenario 3-187

Figure 3) reported that 2 m (6 ft) of subsidence had occurred in the vicinity of the Houston Ship 

Channel by the mid-1970’s as a result of groundwater withdrawal.

Morton et al. (2005) examined localized areas or “hot spots” corresponding to fields in the 

LCA where oil, gas, and brine were extracted at known rates. Morton et al. (2005, Figure 26) shows 

measured subsidence along transects across these fields that range from 18 to 4 mm/yr (0.7 to 

0.15 in), with the greatest rates tending to coincide with the surface footprints of oil or gas fields. 

Mallman and Zoback (2007) interpreted downhole pressure data in several Louisiana oil fields in 

Terrebonne Parish and found localized subsidence over the fields; however, they could not link 

these localized rates to the subsidence measured and observed on a regional scale.

Down-to-the-basin faulting, also called listric or growth faulting, is a long recognized fault 

style along deltaic coastlines, and the Mississippi Delta is no exception (Dokka et al., 2006; 

Gagliano, 2005a). There is currently disagreement in the literature regarding the primary cause of 

modern fault movement in the Mississippi Delta region, and the degree to which it is driven by fluid 

withdrawal or sediment compaction resulting from the sedimentary pile pressing down on soft, 

unconsolidated sediments that causes downward and toward the basin movement along surfaces of 

detachment in the shallow and deep subsurface. Berman (2005) discussed the conclusions of 

Morton et al. (2005) and believed that they failed to make the case that hydrocarbon extraction 

caused substantial subsidence over the broader area of coastal Louisiana, a conclusion also 

reached by Gagliano (2005b).

Oil production on the LCA peaked at 513 MMbbl in 1970 and gas production peaked at 

7.8 MMcf in 1969 (Ko and Day, 2004a). Between 2003 and 2012, oil production from Federal Gulf of 

Mexico waters has continued to decline (U.S. Dept. of Energy, Energy Information Administration, 

2014a). From the peak, the level of production activity is slowly decreasing. The magnitude of 

subsidence caused by formation extraction is a function of how pervasive the activity is across the 

LCA. The oil and gas field maps in Turner and Cahoon (1987, Figure 4) and Ko and Day (2004a, 

Figure 1) seem an adequate basis to estimate the LCA’s oil- and gas-field footprint at ~20 percent of 

the land area. The amount of subsidence from formation extraction is also occurring on a delta 

platform that is experiencing natural subsidence and sea-level rise. Fluid and gas extraction may 

lead to high local subsidence on the scale of individual oil and gas fields but not as a pervasive 

contributor to regional subsidence across the LCA.

3.3.2.8.2 Erosion

BOEM conservatively estimates that there are approximately 4,850 km (3,013 mi) of Federal 

navigation channels, bayous, and rivers potentially exposed to OCS traffic regionwide (Table 3-6) 

and that the average canal is widening at a rate of 0.99 m/year (3.25 ft/year). Regionwide, this 

results in a total annual land loss of approximately 480 ac/yr (1,186 ha/yr).

In the Louisiana Coastal Master Plan (State of Louisiana, Coastal Protection and Restoration 

Authority, 2012), it is estimated that up to 1,750 mi2 (4,500 km2

) of land would be lost in the next 
3-188 Gulf of Mexico Multisale EIS

50 years. Using BOEM’s conservative estimate of approximately 4,850 km (3,014 mi) of Federal 

navigation channels, bayous, and rivers potentially exposed to OCS traffic in the LCA (Table 3-6) 

and the average canal widening rate of -0.99 m/yr (-3.25 ft/yr) (Thatcher et al., 2011), a total land 

loss of approximately 83,053 ac (33,611 ha) in navigation canals may be estimated over the next 

70 years. Using this estimate and comparing it with the total expected land loss in coastal Louisiana 

over the next 50 years, BOEM estimates that approximately 2 percent of the total land loss in 

Louisiana would occur due to salt intrusion, hurricanes, and vessel traffic (OCS Program-related and 

non-OCS Program-related) in navigation canals. Because OCS Program-related vessel traffic 

constitutes such a small percentage (<1%) of the contributing factor to erosion in navigation canals, 

greater than 99 percent of the land loss in coastal Louisiana in the next 70 years can be attributed to 

non-OCS sources.

Net landloss due to navigation canals alone can be calculated by comparing erosion rates 

with beneficial activities such as land gained through the use of dredged sands. BOEM anticipates 

that, over the next 40 years, if current trends in the beneficial use of dredged sand and sediment are 

simply projected based on past land additions (U.S. Dept. of the Army, COE, 2009b), approximately 

50,000 ac (20,234 ha) may be created or protected in the LCA through dredged materials programs.

3.3.2.8.3 Coastal Restoration Programs

The Mississippi Delta sits atop a pile of Mesozoic and Tertiary-aged sediments up to 7.5 mi 

(12.2 km) thick at the coast and it may be as much as 60,000 ft (18,288 m) or 11.4 mi (18.3 km) thick 

offshore (Gagliano, 1999). Five major lobes are generally recognized within about the uppermost 

50 m (164 ft) of sediments (Britsch and Dunbar, 1993; Frazier, 1967, Figure 1). The oldest lobe 

contains peat deposits dated as 7,240 years old (Frazier, 1967). The youngest delta lobe of the 

Mississippi Delta is the Plaquemines-Balize lobe that has been active since the St. Bernard lobe was 

abandoned about 1,000 years ago. The lower Mississippi River has shifted its course to the GOM 

every thousand years or so, seeking the most direct path to the sea while building a new deltaic 

lobe. Older lobes were abandoned to erosion and subsidence as the sediment supply was shut off. 

Because of the dynamics of delta building and abandonment, the Louisiana coastal area (U.S. Dept. 

of the Army, COE, 2004) experiences relatively high rates of subsidence relative to more stable 

coastal areas eastward and westward. Coastal Louisiana wetlands make up the seventh largest 

delta on Earth and undergo about 90 percent of the total coastal wetland loss in the continental 

United States. In fact, from 1932 to 2010, coastal Louisiana has undergone a net change in land 

area of about 1.2 million ac (0.48 million ha). Trend analyses conducted from 1985 to 2010 shows 

that the coastal Louisiana wetland loss rate is 16.57 mi2 (42.92 km2) per year. If this loss were to 

occur at a constant rate, it would equate to Louisiana losing an area the size of one football field per 

hour (Couvillion et al., 2011).

Coastal Wetlands Planning, Protection and Restoration Act

The first systematic program authorized for coastal restoration in the LCA was the 1990 

Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA), otherwise known as the 

“Breaux Act.” Individual CWPPRA projects are designed to protect and restore between 10 and 
Impact-Producing Factors and Scenario 3-189

10,000 ac (4 and 4,047 ha), require an average of 5 years to transition from approval to construction, 

and are funded to operate for 20 years (U.S. Government Accountability Office, 2007), which is a 

typical expectation for project effectiveness (Campbell et al., 2005).

The 1990 CWPPRA introduced an ongoing program of relatively small projects to partially 

restore the coastal ecosystem. As the magnitude of Louisiana’s coastal land losses and ecosystem 

degradation became more apparent, it was identified that a more systematic approach to integrate 

smaller projects with larger projects to restore natural geomorphic structures and processes was 

needed. Projects have ranged from small demonstration projects to projects that cost over 

$50 million. The Coast 2050 report (State of Louisiana, Dept. of Natural Resources, 1998) 

combined previous restoration planning efforts with new initiatives from private citizens, local 

governments, State and Federal agency personnel, and the scientific community to converge on a 

shared vision to sustain the coastal ecosystem. The LCA Ecosystem Restoration Study (U.S. Dept. 

of the Army, COE, 2004a) built upon the Coast 2050 Report. The LCA’s restoration strategies 

generally fell into one of the following categories: (1) freshwater diversion; (2) marsh management; 

(3) hydrologic restoration; (4) sediment diversion; (5) vegetative planting; (6) beneficial use of dredge 

material; (7) barrier island restoration; (8) sediment/nutrient trapping; and (9) shoreline protection, as 

well as other types of projects (Louisiana Coastal Wetlands Conservation and Restoration Task 

Force, 2006, Table 1).

As of March 2015, 200 authorized CWPPRA projects were approved, 101 of which have 

been constructed. Another 18 projects are under construction, 31 are in the engineering and design 

phase, and 50 have been deauthorized or transferred to another program. Over 81,000 “anticipated 

total acres” (32,780 ha) have been projected from completed projects, and 53 projects that were not 

yet completed as of mid-2015 are reported to result in greater than 17,000 anticipated total acres 

(6,879 ha) (LaCoast.gov, 2015). Of the 101 completed projects listed on LaCoast.gov (2015), more 

than half were one of three categories types: shoreline protection projects (30 projects); hydrologic 

restoration projects (24 projects); and marsh creation projects (17 projects).

Following Hurricanes Katrina and Rita in 2005, an earlier emphasis on coastal or ecosystem 

restoration of the LCA was reordered to add an equal emphasis on hurricane flood protection. The 

Department of Defense Appropriations Act of 2006 required Louisiana to create a State organization 

to sponsor the hurricane protection and restoration projects that resulted. The State legislature 

established the Coastal Protection and Restoration Authority (CPRA) and charged it with 

coordinating the efforts of local, State, and Federal agencies to achieve long-term, integrated flood 

control and wetland restoration. The CPRA has since produced comprehensive master plans for a 

sustainable coast (State of Louisiana, Coastal Protection and Restoration Authority, 2007 and 2012) 

as their vision of an integrated program that identified 109 high-performing projects that could 

substantially increase flood protection for communities and create a sustainable coast (State of 

Louisiana, Coastal Protection and Restoration Authority, 2012).

Anticipating which projects are undertaken for COE’s comprehensive range of flood control, 

coastal restoration, and hurricane protection measures for the LCA would feed into the CPRA’s 
3-190 Gulf of Mexico Multisale EIS

Annual Plan for authorization and which ones would ultimately be completed is challenging. Past 

completed projects have the potential of protecting up to 100,000 ac (40,469 ha) of Louisiana’s 

wetlands (State of Louisiana, Coastal Protection and Restoration Authority, 2014); however, 

because CWPPRA projects compete for annual appropriations, there is no simple way to establish 

projections for land added or preserved over the cumulative activities scenario period (2017-2086) 

and the potential protection those projects will provide. Nor is there a way to anticipate which 

projects under the protection of the State’s CPRA are admitted to its Annual Plan and completed.

Louisiana Coastal Master Plan

Since 2007, the CPRA has built or improved 159 mi (256 km) of levees, benefited 19,405 ac 

(7,853 ha) of coastal habitat, secured $17 billion in State and Federal funding, moved over 

150 projects into design and construction, and constructed 32 mi (51 km) of barrier islands/berms 

(State of Louisiana, Coastal Protection and Restoration Authority, 2012). The projects included in 

the Louisiana Coastal Master Plan have the potential to build between 580 and 800 mi2 (1,502 and 

2,072 km2

) of land over the next 50 years, depending on future coastal conditions.

In 2012, Louisiana’s CPRA released a Final Coastal Master Plan, which expanded upon the 

2007 Master Plan. The objectives of the 2012 Master Plan focused on: flood protection, harnessing 

natural processes, supporting coastal habitats, sustaining cultural heritage, and promoting a working 

coast (State of Louisiana, Coastal Protection and Restoration Authority, 2012). The 2012 Louisiana 

Coastal Master Plan was based on a $50 billion budget and targeted use of these funds allows for 

improved protection for communities and could (with additional funding and depending how future 

coastal conditions change) turn the tide of land loss in Louisiana for the first time in a century. The 

$50 billion budget was determined by an estimate of money that Louisiana could receive in the next 

50 years for coastal protection and restoration from sources such as the Gulf of Mexico Energy 

Security Act, Energy and Water Act, Coastal Wetlands Planning and Restoration Act, Deepwater 

Horizon Natural Resources Damage Assessment, Deepwater Horizon Clean Water Act penalties, 

carbon and nutrient credits, future State funding, and Louisiana’s Coastal Protection and Restoration 

Fund.

The CPRA is actively working on the 2017 Coastal Master Plan, which would carry the 2007 

and 2012 Master Plans forward while improving methods, ensuring that projects are completed 

efficiently and effectively while maintaining the vision of the future and adapting to future conditions 

(State of Louisiana, Coastal Protection and Restoration Authority, 2015). In order to develop the list 

of candidate projects for inclusion, the CPRA solicited proposals for new projects to be evaluated. 

Two solicitation periods occurred, one closing on August 21, 2014, and the second closing on 

October 31, 2014. A variety of project ideas were submitted, including bank stabilization, diversions, 

hydrologic restoration, marsh creation, oyster barrier reef restoration, ridge restoration, shoreline 

protection, and structural protection. Project sponsors included agencies, parishes, elected officials, 

nongovernment organizations, and private landowners.
Impact-Producing Factors and Scenario 3-191

As funding becomes available, the CPRA’s Annual Plan is the vehicle for outlining how 

projects are prioritized and implemented. Each Annual Plan would provide project and funding 

details for the current year as well as 2 years into the future. The Annual Plan would provide an 

easy way for citizens and legislators to track progress of the 2012 and 2017 Coastal Master Plans.

Coastal Impact Assistance Program

The Energy Policy Act of 2005 was signed into law by President George W. Bush on 

August 8, 2005. Section 384 of Energy Policy Act amended Section 31 of the OCSLA (43 U.S.C. § 

1356(a)) to establish the Coastal Impact Assistance Program (CIAP). The authority and 

responsibility for the management of CIAP is vested in the Secretary of the Interior; the Secretary 

delegated this authority and responsibility to BOEM until September 30, 2011. Under Section 384, 

Congress directed the Secretary to disburse $250 million for each of the fiscal years 2007 through 

2010 to eligible OCS oil- and gas-producing States and coastal political subdivisions.

On October 1, 2011, the FWS took over administration of CIAP as directed by the Secretary 

because the program aligned with FWS’s conservation mission and similar grant programs run by 

the FWS. The eligibility requirements for States, coastal political subdivisions, and fundable projects 

remained largely the same after the transfer.

The CIAP provides Federal grant funds derived from Federal offshore lease revenues to oilproducing states for conservation, protection, or restoration of coastal areas. The funds can be 

directed to a number of different projects, including restoration of wetlands; mitigation of damage to 

fish, wildlife, or natural resources; planning assistance and payment of the administrative costs of 

complying with these objectives; implementation of a federally approved marine, coastal, or 

comprehensive conservation management plan; and mitigation of the impacts of OCS oil- and gasrelated activities through the funding of onshore infrastructure projects and public service needs. 

Eligible CIAP States Eligible CIAP Coastal Political Subdivisions

Alabama Baldwin and Mobile Counties

Alaska

Municipality of Anchorage and Bristol Bay, Kenai Peninsula, Kodiak Island, 

Lake and Peninsula, Matanuska-Susitna, North Slope, and Northwest Arctic 

Boroughs

California

Alameda, Contra Costa, Los Angeles, Marin, Monterey, Napa, Orange, San 

Diego, San Francisco, San Luis Obispo, San Mateo, Santa Barbara, Santa 

Clara, Santa Cruz, Solano, Sonoma, and Ventura Counties

Louisiana

Assumption, Calcasieu, Cameron, Iberia, Jefferson, Lafourche, Livingston, 

Orleans, Plaquemines, St. Bernard, St. Charles, St. James, St. John the 

Baptist, St. Martin, St. Mary, St. Tammany, Tangipahoa, Terrebonne, and 

Vermilion Parishes

Mississippi Hancock, Harrison, and Jackson Counties

Texas

Aransas, Brazoria, Calhoun, Cameron, Chambers, Galveston, Harris, 

Jackson, Jefferson, Kennedy, Kleberg, Matagorda, Nueces, Orange, Refugio, 

San Patricio, Victoria, and Willacy Counties

CIAP = Coastal Impact Assistance Program.
3-192 Gulf of Mexico Multisale EIS

Natural Resource Damage Assessment

The Oil Pollution Act of 1990, as provided in 33 U.S.C. § 2706, allowed the designation of 

the Natural Resource Damage Assessment Trustee Council (Trustee Council), which included 

certain Federal agencies, States, and Indian Tribes. Executive Order 13554, which was signed on 

October 5, 2010, recognized the role of the Trustee Council under the Oil Pollution Act and 

“designated trustees as provided in 33 U.S.C. 2706, with trusteeship over those natural resources 

injured, lost, or destroyed as a result of the Deepwater Horizon oil spill.” Specifically, Executive 

Order 13554 recognized the importance of carefully coordinating the work of the Gulf Coast 

Ecosystem Task Force with the Trustee Council, “whose members have statutory responsibility to 

assess natural resource damages from the Deepwater Horizon oil spill, to restore trust resources, 

and seek compensation for lost use of those trust resources” (The White House, 2012). The Task 

Force, on the other hand, was charged with creating a plan to improve the overall health of the Gulf 

of Mexico area and has focused on a number of stressors to the Gulf Coast ecosystem beyond 

those caused by the Deepwater Horizon explosion, oil spill, and response. While the work of the 

Task Force has been independent from the work of the Trustees, the valuable information gathered 

by the Task Force will be useful to the Trustees in their restoration planning efforts (USDOC, NOAA, 

2015e).

The NRDA activities for the BP oil spill have been divided into the categories below and 

focus on specific species, habitats, or uses (USDOC, NOAA, 2015f):

• marine mammals and sea turtles;

• fish and shellfish;

• birds;

• deepwater habitat (e.g., deepwater coral);

• nearshore habitats (including seagrasses, mud flats, and coral reefs);

• shoreline habitats (including salt marsh, beaches, and mangroves);

• land-based wildlife and habitat; and

• public uses of natural resources (including recreational fishing, boating, beach 

closures).

The Trustee Council is currently in Phase III of early restoration, and the data collection, 

analysis, and restoration are ongoing (USDOI, 2015). The final Phase III plan proposes $627 million 

for 44 new early restoration projects across the Gulf Coast States. It also includes plans to prepare 

a programmatic EIS and programmatic restoration plan for early restoration (USDOC, NOAA, 

2015g).
Impact-Producing Factors and Scenario 3-193

Resources and Ecosystems Sustainability, Tourist Opportunities, and Revived Economies of 

the Gulf Coast States Act

In July 2012, in response to the Deepwater Horizon explosion, oil spill, and response and 

other environmental challenges in the Gulf Coast region, Congress passed the Resources and 

Ecosystems Sustainability, Tourist Opportunities, and Revived Economies of the Gulf Coast States 

Act or the RESTORE Act, (Gulf Coast Ecosystem Restoration Council, 2015). In September 2012, 

an Executive Order was released affirming the Federal Government’s Gulf Coast ecosystem 

restoration efforts in light of the recent passage of the RESTORE Act, which created a Gulf Coast 

Restoration Trust Fund (Trust Fund), outlined a structure for allocating the Trust Fund, and 

established the Gulf Coast Ecosystem Restoration Council (Council) (The White House, 2012). The 

Council is comprised of governors from the five affected Gulf Coast States, the Secretaries from the 

U.S. Departments of the Interior, Commerce, Agriculture, and Homeland Security, as well as the 

Secretary of the Army and the Administrator of the U.S. Environmental Protection Agency. The Gulf 

Coast States recommended and President Obama appointed the Secretary of Commerce as the 

Council’s Chair. As an independent entity, the Council has responsibilities with respect to 60 

percent of the funds made available from a Gulf Coast Restoration Trust Fund and is charged with 

developing a comprehensive plan for ecosystem restoration on the Gulf Coast (Comprehensive 

Plan), as well as any future revisions to the Comprehensive Plan (Gulf Coast Ecosystem Restoration 

Council, 2014).

The Initial Comprehensive Plan, approved in August 2013, establishes the Council’s goals 

defined as: (1) restore and conserve habitat; (2) restore water quality; (3) replenish and protect 

living coastal and marine resources; (4) enhance community resilience; and (5) restore and revitalize 

the GOM economy (The White House, 2012). In July 2014, the Council approved a proposal 

submission and evaluation process to select projects for inclusion on the draft Funded Priorities List, 

which will be included as an addendum to the Initial Comprehensive Plan. This first Funded 

Priorities List addendum would contain projects and programs that will be funded with available 

Transocean Deepwater Inc. funds. Future amendments to this Funded Priorities List and the 

process by which projects are selected for inclusion would evolve over time as new information 

becomes available, adaptive management activities occur, and as funding uncertainties are resolved 

(Gulf Coast Ecosystem Restoration Council, 2014). As a result of the settlement of Clean Water Act 

civil claims against Transocean Deepwater Inc. and related entities, a total of approximately 

$800 million, plus interest, was deposited in the Trust Fund between 2013 and 2015. Thus, based 

upon the RESTORE Act and the payment schedule agreed to by the court for the Transocean 

settlement, by February 20, 2015, 30 percent of that total amount (i.e., $240 million plus interest) 

was deposited in the Trust Fund for allocation by the Council under the Council-Selected Restoration 

Component (Gulf Coast Ecosystem Restoration Council, 2013).

Among its other duties, the Council is tasked with establishing additional advisory 

committees as may be necessary to assist the Council, including a scientific advisory committee and 

a committee to advise the Council on public policy issues; gathering information relevant to Gulf 
3-194 Gulf of Mexico Multisale EIS

Coast restoration, including thorough research, modeling, and monitoring; and providing an annual 

report to Congress on implementation progress (The White House, 2012).

As outlined in the RESTORE Act, the Council submitted a 2014 Annual Report to Congress 

on the implementation progress (Gulf Coast Ecosystem Restoration Council, 2014). In 2015, the 

Council proposed regulation that would establish the formula allocating funds made available from 

the Gulf Coast Restoration Trust Fund among the Gulf Coast States of Alabama, Florida, Louisiana, 

Mississippi and Texas (Federal Register, 2015d). The Council also released a draft initial-funded 

priorities list (Gulf Coast Ecosystem Restoration Council, 2015).

National Fish and Wildlife Foundation: Gulf Environmental Benefit Fund

In early 2013, a U.S. District Court approved two plea agreements resolving certain criminal 

cases against BP and Transocean, cases which arose from the 2010 Deepwater Horizon explosion, 

oil spill, and response. The agreements direct a total of $2.544 billion to the National Fish and 

Wildlife Foundation to fund projects benefiting the natural resources of the Gulf Coast that were 

impacted by the spill.

Between 2013 and 2018, the National Fish and Wildlife Foundation’s newly established Gulf

Environmental Benefit Fund will receive a total of $1.272 billion for barrier island and river diversion 

projects in Louisiana; $356 million each for natural resource projects in Alabama, Florida, and 

Mississippi; and $203 million for similar projects in Texas. Funding priorities include projects that

• restore and maintain the ecological functions of landscape-scale coastal habitats, 

including barrier islands, beaches, and coastal marshes, and ensure their viability 

and resilience against existing and future threats, such as sea-level rise;

• restore and maintain the ecological integrity of priority coastal bays and 

estuaries; and

• replenish and protect living resources including oysters, red snapper and other 

reef fish, Gulf Coast bird populations, sea turtles, and marine mammals (National 

Fish and Wildlife Foundation, 2015a).

As of 2015, the Gulf Environmental Benefit Fund has supported 50 projects worth nearly 

$390 million. In making the awards, the National Fish and Wildlife Foundation has worked closely 

with key State and Federal resource agencies to select projects that remedy harm and eliminate or 

reduce the risk of future harm to Gulf Coast natural resources. For example, funding was awarded 

from the Gulf Environmental Benefit Fund for engineering and construction of both Caminada Beach 

and Dune Increment II and East Timbalier Island, both involving the use of OCS sediment resources 

(National Fish and Wildlife Foundation, 2015b).
Impact-Producing Factors and Scenario 3-195

3.3.2.8.4 Saltwater Intrusion

Saltwater intrusion is one of many factors that impact coastal environments, contributing to 

coastal land loss. Such impacts can be natural, as when storm surge brings GOM water inland, or 

anthropogenic, as when navigation or pipeline canals allow tides to introduce high salinity water to 

interior marshes. In addition, produced water from oil wells in the coastal zones can be a source of 

water of extreme high salinity, well over 100 parts per thousand. Produced water, which is 

regulated, often contains pollutants such as heavy metals and hydrocarbons, as well.

Marsh plants are exposed to salinity stress when higher salinity GOM waters reach interior 

marshes, exposing plants to salinities above their tolerance levels. This can result in decreased 

plant growth and/or mortality depending on the tolerance of the plant species and the amount, rate, 

and duration of salinity increase (Mendelssohn and McKee, 1987). Plant dieback can be followed by 

subsequent erosion of the marsh substrate and eventual land loss (Ko and Day, 2004; Boesch et al., 

1994).

The freshwater-adapted habitats (i.e., fresh or intermediate marsh and forested wetlands) 

are more sensitive to saltwater intrusion than the other more salt-tolerant habitats, such as brackish 

and saline marsh. Saltwater intrusion can result in conversion of freshwater to saline habitats or can 

simply kill fresh or intermediate marshes, thus converting them to open water (Johnston et al., 2009).

The leveeing of the Mississippi River and the construction of numerous water control 

structures are generally thought to have accelerated coastal land loss by isolating coastal wetlands 

from the freshwater, sediment, and nutrients of the Mississippi River, which previously served to 

nourish and sustain these wetlands. Among other impacts, this isolation effect results in the loss or 

reduction in freshwater flow, and thus a greater marine influence on the coastal wetlands, which in 

turn results in saltwater intrusion (Johnston, et al., 2009).

Saltwater intrusion into coastal environments can also impact estuarine species distribution, 

shifting patterns of habitat usage. Marine species penetrate farther inland when salinities are within 

their tolerance, and less salt-tolerant species are restricted to the fresher areas. This can also lead 

to a shift in the pattern of availability of preferred fish species to fishermen.

3.3.2.8.5 Maintenance Dredging and Federal Channels

Along the Texas Coast there are eight federally maintained navigation channels in addition to 

the GIWW. 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-gained material. 

Ocean disposal locations along the Texas coast are situated so that materials are placed on the 

down drift side of the channel (U.S. Dept. of the Army, COE, 1992,).

There are 10 Federal navigation channels in the LCA, ranging in depth from 4 to 14 m (12 to 

45 ft) and in width from 38 to 300 m (125 to 1,000 ft), that were constructed as public works projects 
3-196 Gulf of Mexico Multisale EIS

beginning in the 1800’s (Good et al., 1995, Table 1). The combined length of the Federal channels 

in Good et al. was reported as 2,575 mi (1,600 km), with three canals considered deep-draft and 

seven considered shallow (Good et al., 1995, page 9). The Federal navigation channels in 

Louisiana identified by Good et al. (1995, Table 1) are as follows: (1) GIWW East of Mississippi 

River; (2) Mississippi River Gulf Outlet; (3) GIWW between the Atchafalaya and Mississippi Rivers; 

(4) GIWW West of Atchafalaya River; (5) Barataria Bay Waterway; (6) Bayou Lafourche; (7) Houma 

Navigation Canal; (8) Mermentau Navigation Channel; (9) Freshwater Bayou; and (10) Calcasieu 

River Ship Channel. The Mississippi River Gulf Outlet has been decommissioned and sealed with a 

rock barrier as of July 2009 (Shaffer et al., 2009, page 218).

The GIWW is a Federal, shallow-draft navigation channel constructed to provide a domestic 

connection between GOM ports after the discovery of oil in East Texas in the early 1900’s, as well 

as to provide a pathway to support the growing need for interstate transport of steel and other 

manufacturing materials in the early 20th century. It extends approximately 1,400 mi (2,253 km) 

along the Gulf Coast from St. Marks in northwestern Florida to Brownsville, Texas, with the 

Louisiana part reported to be 994 mi (1,600 km) in length (Good et al., 1995). With the exception of 

the east-west GIWW in Louisiana, Federal channels are approximately north-south in orientation, 

making them vulnerable to saltwater intrusion during storms (refer to Chapter 3.3.2.8.4 above).

Cumulative impacts include the displacement of wetlands by original channel excavation and 

disposal of the dredged material. Turner and Cahoon (1987, Table 4-5) estimated that immediate 

impacts from the construction of navigation channels were between 58,000 and 96,000 ac 

(23,472 and 38,850 ha). Indirect cumulative land losses resulted from hydrologic modifications, 

saltwater intrusion, or bank erosion from vessel wakes (Wang, 1988). Once cut, navigation canals 

tend to widen as banks erode and subside, depending on the amount of traffic using the channel. 

Good et al. (1995, Table 1) estimated indirect impacts on wetland loss from bank erosion at 

35,000 ac (14,164 ha).

The COE reported that the New Orleans District has the largest channel maintenance 

dredging program in the U.S., with an annual average of 70 million yd3 (53.5 million m3

) of material 

dredged (U.S. Dept. of the Army, COE, 2009a). Maintenance dredging activity from 2004 through 

2013 for Federal channels by COE’s Galveston District, New Orleans District, and Mobile District are 

reported in COE’s Ocean Disposal Database (U.S. Dept. of the Army, COE, 2015a) (Table 3-26). 

The average amount of material disposed of in the 10-year period is highest for the New Orleans 

District (14,737,321 yd3 [11,267,495 m3

]), followed by the Galveston District (6,788,997 yd3

[5,190,563 m3

]) and the Mobile District (4,612,358 yd3 [3,526,402 m3]). Federal channels and canals 

are maintained throughout the onshore cumulative impact area by the COE, State, county, 

commercial, and private interests. Proposals for new and maintenance dredging projects are 

reviewed by Federal, State, and local agencies as well as by private and commercial interests to 

identify and mitigate adverse impacts upon social, economic, and environmental resources.

Maintenance dredging is performed on an as-needed basis. Typically, the COE schedules 

surveys every 2 years on each navigation channel under its responsibility to determine the need for 
Impact-Producing Factors and Scenario 3-197

maintenance dredging. Dredging cycles may be from 1 to as many as 11 years from channel to 

channel and from channel segment to channel segment. The COE is charged with maintaining all 

larger navigation channels in the cumulative activities area. The COE dredges millions of cubic 

meters of material per year in the cumulative activities area, most of which is under the responsibility 

of the New Orleans District. Some shallower port-access channels may be deepened over the next 

10 years to accommodate deeper draft vessels. Vessels that support deepwater OCS oil- and gasrelated activities may include those with drafts to about 7 m (23 ft).

Construction and maintenance dredging of rivers and navigation channels can furnish 

sediment for a beneficial purpose, a practice the COE calls beneficial use of dredge materials 

program. Drilling, production activity, and maintenance at most coastal well sites in Louisiana 

require service access canals that undergo some degree of aperiodic maintenance dredging to 

maintain channel depth, although oil and gas production on State lands peaked in 1969-1970 (Ko 

and Day, 2004a, page 398). In recent years, dredged materials have been sidecast to form new 

wetlands using the beneficial use of dredge materials program. Potential areas suited for beneficial 

use of dredged material are considered most feasible within a 10-mi (16-km) boundary around 

authorized navigation channels in the New Orleans District, but the potential for future long-distance 

pipelines for disposal of dredged material could increase the potential area available for the 

beneficial use of dredge materials program considerably (U.S. Dept. of the Army, COE, 2009a, 

page 27).

As discussed in Chapter 3.3.2.3.5, the New Orleans District dredges an average annual 

14.7 million yd3 (11.3 million m3

) of material. Current figures estimate that approximately 38 percent 

of that average is available for the beneficial use of the dredge materials program (U.S. Dept. of the 

Army, COE, 2013). The COE reported that, over the last 20 years, approximately 12,545 ha 

(31,000 ac) of wetlands have been created with dredged materials, most of which are located on the 

LCA delta plain (U.S. Dept. of the Army, COE, 2013).

3.3.2.9 Natural Events and Processes

3.3.2.9.1 Physical Oceanography

Physical oceanographic processes in the GOM include the Loop Current, Loop Current

eddies, and whirlpool-like features that appear underneath the Loop Current and Loop Current

eddies that interact with the bottom. Infrequently observed processes include a limited number of

high-speed current events, at times approaching 100 cm/s (39 in/s). These events were observed at

depths exceeding 1,500 m (4,921 ft) in the northern GOM (Hamilton and Lugo-Fernandez, 2001;

Hamilton et al., 2003) and as very high-speed currents in the upper portions of the water column

observed in deep water by several oil and gas operators.

Caribbean Sea waters colliding with the Yucatan Peninsula turn northward and enter the

Yucatan Channel as a strong flow called the Yucatan Current. This current exhibits two basic

arrangements inside the Gulf of Mexico. First, the Yucatan Current enters the GOM and turns

immediately eastward, exiting the GOM towards the Atlantic Ocean via the Florida Straits to become
3-198 Gulf of Mexico Multisale EIS

the Gulf Stream. The second arrangement consists of a northward penetration of the Yucatan

Current into the Gulf of Mexico reaching to 26o-28o N. latitudes, then curls clockwise turning south,

and exiting via the Florida Straits into the Atlantic Ocean to become, again, the Gulf Stream. This

circulation inside the GOM is called the Loop Current. The Loop Current transports warm and salty

water year round into the GOM at a rate of 25-30 million cubic meters per second, and it is the main

energy source for oceanographic processes inside the Gulf of Mexico. At its climatic northern

position, the Loop Current becomes unstable, breaks, and sheds a large (200- to 400-km diameter

[124- to 248-mi diameter]) clockwise whirlpool that travels southwestwards at speeds of 4-8 km/day

(2-5 mi/day). The southwest trip of Loop Current eddies continues until colliding with the Texas and

Mexico continental slope in the western GOM, where they disintegrate. This sequence connects the

eastern with the western Gulf, which otherwise appear disconnected.

Mean seasonal circulation patterns of inner-shelf and outer-shelf currents on the LouisianaTexas continental shelf, the northeastern GOM shelf, and the West Florida shelf are primarily wind

driven and are also influenced by riverine outflow. Cold water from deeper off-shelf regions moves

onto and off the continental shelf by cross-shelf flow associated with upwelling and downwelling

processes in some locations (Collard and Lugo-Fernandez, 1999). There are also a number of

secondary whirlpools with smaller diameters (50-100 km; 31-62 mi) that affect the exchange

between the shelf and deepwater, and these smaller whirlpools interact with the larger Loop Current

eddies (Donohue et al., 2008). Additionally, wind events such as tropical cyclones (especially

hurricanes), extratropical cyclones, and cold-air outbreaks can result in extreme waves and cause

currents with speeds of 100-150 cm/s (39-59 in/s) over continental shelves.

Deepwater currents of the GOM can be approximated as a two-layer system with an upper

layer about 800- to 1,000-m (2,625- to 3,281-ft) deep that is dominated by the Loop Current and

associated clockwise whirlpools and a lower layer below ~1,000 m (3,281 ft) that has near uniform

currents (Cox et al., 2010; Welsh et al., 2009; Inoue et al., 2008). The coupling between these two

layers is generally absent, but it appears that motions at the layer interface are needed to transmit

the energy from the Loop Current and eddies downward (Cox et al., 2010; Welsh et al., 2009; Inoue

et al., 2008, Donohue et al., 2008). Mean deep flow around the edges of the GOM circulates in a 

counterclockwise direction, as observed at ~2,000 m (6,562 ft) (Sturges et al., 2004) and at ~900 m 

(2,953 ft) (Weatherly, 2004), with current speeds generally decreasing with depth.

3.3.2.9.2 Natural Seeps

“Natural seeps” is used here to mean the naturally occurring seepage of crude oil and tar into 

the GOM. These seeps are geographically common and have likely been active throughout history. 

Natural seeps account for approximately 47 percent of the crude oil entering the marine environment 

(Kvenvolden and Cooper, 2003). Mitchell et al. (1999) estimated a range of 280,000-700,000 bbl 

per year (40,000-100,000 tonnes per year), with an average of 490,000 bbl (70,000 tonnes) for the 

northern GOM, excluding the Bay of Campeche. Using this estimate and assuming seep scales are 

proportional to surface area, the NRC (2003) estimated annual seepage for the entire GOM at 

~980,000 bbl (140,000 tonnes) per year, or about 3 times the estimated amount of oil spilled by the 
Impact-Producing Factors and Scenario 3-199

1989 Exxon Valdez event (~270,000 bbl) (Steyn, 2010) or a quarter of the amount released into the 

environment by the Deepwater Horizon explosion and oil spill (4.1 MMbbl of oil) (Lubchenco et al., 

2010). As seepage is a natural occurrence, the rate of ~980,000 bbl (140,000 tonnes) per year is 

expected to remain unchanged throughout the cumulative analysis period. Refer to Chapter 4.4 for 

more information on natural seeps.

3.3.2.9.3 Hurricanes

Climatic cycles in tropical latitudes typically last 20-30 years or even longer (USDOC, NOAA, 

2005). As a result, the North Atlantic experiences alternating periods of above-normal or belownormal hurricane seasons. There is a two- to three-fold increase in hurricane activity during eras of 

above-normal activity. The hurricane activity from 1995 to 2007 is representative of an era of abovenormal hurricane activity (Elsner et al., 2008, page 1,210).

Twenty-one hurricanes made landfall in the WPA, CPA and EPA during the 1995-2015 

hurricane seasons, disrupting OCS oil- and gas-related activity in the GOM (Table 3-30). Half of 

these hurricanes reached a maximum strength of Category 1 or 2 while in the CPA or WPA, while 

the other half were powerful hurricanes reaching maximum strengths of Category 4 or 5. The 

current era of heightened Atlantic hurricane activity began in 1995; therefore, the Gulf of Mexico 

could expect below average hurricanes in the GOM in the near term due to a strong El Nino. 

Increased hurricanes may occur if El Nino wanes during the first half of the 50-year analysis period 

and levels return to below-normal activity during the remaining half to three-quarters of the 50-year 

analysis period.

Table 3-30. Hurricane Landfalls in the Northern Gulf of Mexico from 1995 through 2015.

Event Year Affected State Storm Name Intensity at Landfall

1 1995 AL, FL Opal Hurricane Category 3

2 1995 FL Erin Hurricane Category 2

3 1997 LA, AL Danny Hurricane Category 1

4 1998 FL Earl Hurricane Category 1

5 1998 MS, AL Georges Hurricane Category 2

6 1999 TX Bret Hurricane Category 3

7 2002 LA Lili Hurricane Category 1

8 2003 TX Claudette Hurricane Category 1

9 2004 FL Charley Hurricane Category 4

10 2004 FL Frances Hurricane Category 2

11 2004 MS, AL Ivan Hurricane Category 3

12 2005 LA, MS Cindy Hurricane Category 1

13 2005 FL, AL Dennis Hurricane Category 3

14 2005 LA, MS Katrina Hurricane Category 5

15 2005 TX, LA Rita Hurricane Category 3

16 2005 FL Wilma Hurricane Category 3

17 2007 TX, LA Humberto Hurricane Category 1
3-200 Gulf of Mexico Multisale EIS

Event Year Affected State Storm Name Intensity at Landfall

18 2008 LA Gustav Hurricane Category 2

19 2008 TX, LA Ike Hurricane Category 4

20 2008 TX Dolly Hurricane Category 1

21 2012 LA Isaac Hurricane Category 1

Note: There were no hurricane landfalls in the northern Gulf of Mexico in 2009-2011 and 

2013-2015.

Source: USDOC, NOAA, 2016a.

Hurricanes Ivan, Katrina, Rita, Gustav, and Ike entered the GOM and destroyed 

181 structures and 1,673 wells on the OCS (Kaiser, 2015a). In general, they caused extensive 

damage to OCS platforms, topside facilities, and pipeline systems (Table 3-31). During Hurricanes 

Ivan, Katrina, and Rita, 9 jack-up rigs and 19 moored rigs were either toppled or torn from their 

mooring systems. Sixty platforms were destroyed as a result of Hurricanes Gustav and Ike in 2008, 

31 platforms had extensive damage, and 93 platforms had moderate damage (USDOI, MMS, 

2008b). The number of destroyed platforms by Hurricanes Gustav and Ike exceeds the number 

destroyed by Hurricane Katrina. Hurricane Isaac made landfall near the mouth of the Mississippi 

River on August 28, 2012, as a Category 1 hurricane, which only caused very minor damage to the 

offshore oil or gas infrastructure in the GOM. However, after Hurricane Isaac, tarballs and tar mat 

fragments were found along Alabama’s shoreline (Auburn University, 2012). It was also observed 

that Hurricane Isaac resulted in the suspension of small amounts of tarballs and some oil from 

sediments (Mulagabal et al., 2013). Refer to Chapter 3.2.4 for additional details for pipeline failures 

caused by hurricanes.

Table 3-31. Oil Spilled from Pipelines on the Federal OCS, 2002-2009.

Regulator Area Total Oil Spilled 

(bbl)

Oil Spilled due to 

Hurricanes 

(bbl)

Proportion of Total Oil Spilled

due to Hurricanes 

(%)

BOEM Federal OCS 5,522 5,179 94

DOT Federal OCS 5,667 3,272 58

DOT State Waters 9,903 9,622 97

Source: USDOI, BOEMRE, 2011c.

3.3.2.9.4 Climate Change

Issues related to climate change, including global warming, sea-level rise, and programmatic 

aspects of climate change relative to the environmental baseline for the GOM are discussed in 

Chapter 4.2.1 of the Five-Year Program EIS.

3.3.2.10 Mississippi River Hydromodification

The Mississippi River has been anchored in place by engineered structures built in the 

20th century and has been hydrologically isolated from the delta it built. The natural processes that 
Impact-Producing Factors and Scenario 3-201

allowed the river to flood and distribute alluvial sediments across the delta platform and channels to 

meander have been shut down. Hydromodifying interventions include construction of (1) levees 

along the river and distributary channel systems, (2) upstream dams and flood control structures that 

impound sediment and meter the river flow rate, and (3) channelized channels with earthen or 

armored banks. Once the natural processes that act to add sediment to the delta platform to keep it 

emergent are shut down, subsidence begins to outpace deposition of sediment.

Of total upstream-to-downstream flow, the Old River Control Structure (built 1963) diverts 

70 percent of flow down the levee-confined channels of the Mississippi River and 30 percent down 

the unconfined Atchafalaya River, which has been actively aggrading its delta plain since 1973 

(LaCoast.gov, 2011). Blum and Roberts reported that the time-averaged sediment load carried by 

the Mississippi and Atchafalaya Rivers before installation of the Old River Control Structure was 

~400-500 million tons per year and that the average suspended load available to either river after 

construction of the Old River Control Structure was ~205 million tons per year (Blum and Roberts, 

2009, Figure 2). Modern sediment loads are, therefore, less than half that is required to build and 

maintain the modern delta plain, a figure largely in agreement with previous work reporting 

decreases in suspended sediment load of nearly 60 percent since the 1950’s (Turner and Cahoon, 

1987; Tuttle and Combe, 1981).

Blum and Roberts (2009, Figure 3b) posited three scenarios for subsidence and sea-level 

rise, and concluded that sediment starvation alone would cause ~2,286 mi2 (592,071 ha) of the 

modern delta plain to submerge by 2050 without any other impacting factors contributing to land 

loss. The use of sediment budget modeling, a relatively new tool for land loss assessment, appears 

to indicate that hydrographic modification of the Mississippi River has been the most profound mancaused influence on land loss in the LCA. Sediment starvation of the deltaic system is allowing 

rising sea level and subsidence to outpace the constructive processes building and maintaining the 

delta.

BOEM anticipates that, over the next 50 years, there might be minor sediment additions 

resulting from new and continuing freshwater diversion projects managed by the COE. Refer to 

Chapter 3.3.2.8.3 for more information on coastal restoration.

3.3.2.11 Mississippi River Eutrophication

The Mississippi River Basin drains 41 percent of the contiguous United States. The basin 

covers more than 1,245,000 mi2 (3,224,535 km2

) and includes all or parts of 31 states and 

2 Canadian provinces (U.S. Dept. of the Army, COE, 2015b). Dissolved pollutants, including 

nutrients, enter surface water within the Mississippi River Basin via uncontained runoff and 

groundwater discharge (nonpoint sources).

The sources of nutrients in surface waters can be broadly divided as natural and 

anthropogenic. Natural sources are generally ubiquitous; however, their contribution is usually low 

because, over the course of time, natural systems have established balances between the 
3-202 Gulf of Mexico Multisale EIS

production and consumption of nutrients. Anthropogenic sources arise from many activities. In the 

agricultural setting of the Mississippi River drainage basin, farmers increase the productivity and 

yield of their crops by use of chemical fertilizers. If more fertilizers are applied than are used by the 

crops, they can move into ground and surface waters and become a major source of nutrients in 

rivers. Additionally, fertilizer that is bound to soil or “loose” fertilizer may be subject to erosion by 

wind or water and affect surface waters. Information regarding nutrient management can be found 

on the U.S. Department of Agriculture’s Natural Resources Conservation Service website (USDA, 

NRCS, 2015). Other major sources of nutrients in surface waters are domestic and animal wastes. 

Although municipal wastewater is treated, only a fraction of the nutrients is removed. In addition to 

the nutrients derived from human sewage, municipal wastewater also contains nutrients from such 

things as lawn fertilizers, household cleaners, and detergents. Other anthropogenic sources of 

nutrients are industrial, either from the manufacture of fertilizers or as by-products of other 

manufacturing processes (Antweiler et al., 1995).

The most significant inorganic forms of two elements, nitrogen and phosphorus, include four 

nutrient compounds: nitrate (NO3

-

); nitrite (NO2

-

); ammonium (NH4

+

); and orthophosphate (PO4

-3). 

Of these four major nutrient compounds, only nitrate is found in concentrations approaching the 

USEPA’s maximum contaminant level of 10 mg/L. Orthophosphate usually is present in low 

concentrations, and concentrations of ammonium and nitrite usually are insignificant (USDOI, GS, 

1995).

Nutrient enrichment results in eutrophication, causing growth of algae (algal bloom) and 

other aquatic plants. A second effect of eutrophication is the increased uptake of dissolved oxygen 

by bacteria in response to higher concentrations of organic matter. If oxygen is taken up by 

decaying organic matter faster than it is imported from the atmosphere or produced by 

photosynthesis, it becomes depleted, and the aquatic species that require it are adversely affected. 

Furthermore, oxygen depletion causes basic changes in the chemical environment (i.e., a reduced 

environment) that allow materials (including many metals) that were formerly associated with the 

solid phase sediments (e.g., sorbed) to become soluble and, therefore, more mobile in the aqueous 

phase (USDOI, GS, 1995).

On October 21, 2014, the U.S. Department of the Interior and the U.S. Department of 

Agriculture announced a new partnership to strengthen the effectiveness of State and Federal 

nutrient-reduction strategies (USDOI, GS, 2014). As a result of this and other efforts, states are 

beginning to impose Best Management Practices on growers within the Mississippi River Basin to 

develop nutrient management plans, including fertilizer applicator certification programs, and 

monitoring to minimize excess nutrients from washing into waterways.

3.3.2.12 Hypoxia

The Gulf of Mexico hypoxic zone is a band of oxygen-stratified water that stretches along the 

Texas-Louisiana shelf each summer where the dissolved oxygen concentrations are less than 

2 mg/L (USEPA, 2015b). Other small hypoxic areas infrequently form at the discharge of smaller 
Impact-Producing Factors and Scenario 3-203

rivers along the Gulf Coast; however, in the Gulf of Mexico, the hypoxic zone resulting from the 

Mississippi and Atchafalaya Rivers is by far the predominant feature. The hypoxic zone is the result 

of excess nutrients, primarily nitrogen, carried downstream by rivers to discharge to coastal waters. 

Density stratification results where the less dense, nutrient-rich freshwater spreads on top of the 

denser seawater and prevents oxygen from replenishing the bottom waters. The excess nutrients 

cause phytoplankton blooms that eventually die and sink to the bottom, where bacterial 

decomposition consumes dissolved oxygen. The oxygen-depleted bottom waters occur seasonally 

and are affected by the timing of the Mississippi and Atchafalaya Rivers’ discharges carrying 

nutrients and freshwater to shelf surface waters. Hypoxic zones are sometimes called “dead zones” 

because of the absence of commercial quantities of shrimp and fish in the bottom layer.

The hypoxic zone on the Louisiana-Texas shelf is the largest such zone in the United States 

and the entire western Atlantic Ocean (Turner et al., 2005). The Louisiana Universities Marine 

Consortium 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 the Louisiana Universities Marine Consortium in 

July of each year. Recent estimates of the area of low oxygen by NOAA (USDOC, NOAA, 2015) as 

of August 3, 2015, measured 6,474 mi2 (16,700 km2

) (Figure 3-15), an increase from the size 

measured in 2014 (5,052 mi2

) and larger than the estimated size (5,838 mi2) forecast by the 

Louisiana Universities Marine Consortium (2015) in June 2015 and three times larger than the 

Action Plan Goal of 5,000 km2 or 1,991 mi2 (Louisiana Universities Marine Consortium, 2014). The 

hypoxic zone extends up to 60-70 km (37-43 mi) from the shoreline, well into OCS waters. 

Figure 3-15. 2015 Gulf of Mexico Hypoxic Zone (USDOC, NOAA, 2015h).

Rabelais (2005) and Bierman et al. (2008) evaluated the potential contributions of carbon 

and nitrogen in discharged produced waters on the hypoxic zone. Both studies found that the 

effects due to produced water were minimal compared with those of the Mississippi River. As such, 
3-204 Gulf of Mexico Multisale EIS

the Louisiana-Texas hypoxic zone is considered to be unrelated to OCS oil- and gas-related 

activities but is discussed here as a potential cumulative effect.

3.3.2.13 Sedimentation

The lower Mississippi River, from Cairo, Illinois, to the Gulf of Mexico, transported an 

average of 150 million tons (with a range of 70-230 million tons) of sediment annually between 1963 

and 2005. Historically, the quantity of sediment derived from catchment erosion has been affected 

by changes in land use and river management, increasing in the 19th and early 20th centuries before 

decreasing due to soil conservation and improved land management. Seasonal analysis shows that, 

in the spring, the median load is approximately four times the median total load in the fall. The 

median sediment size is mostly silt, but it coarsens during the winter and spring when 10 percent of 

the sediment load is coarser than fine sand (U.S. Dept. of the Army, European Research Office, 

2008).

Suspended sediment and bed load enter the GOM from the outlets of the Mississippi and 

Atchafalaya Rivers. Suspended sediment is circulated along the Louisiana-Texas continental shelf 

where it settles out and may later become resuspended during storms. Bed-load sediment 

discharge builds the Mississippi and Atchafalaya River deltas and may be redistributed on the 

continental shelf by currents and wave action. Sediment on the continental shelf may ultimately be 

intercepted by the Mississippi Canyon where it is transported downslope to the Mississippi Fan in 

deep water.

Since the marine environment is a dynamic system, sediment quality and water quality can 

affect each other. For example, a contaminant may react with the mineral particles in the sediment 

and be removed from the water column (e.g., adsorption). Thus, under appropriate conditions, 

sediments can serve as sinks for contaminants such as metals, nutrients, or organic compounds. 

However, if sediments are resuspended (e.g., due to dredging or a storm event), the resuspension 

can lead to a temporary redox flux, including a localized and temporal release of any formally sorbed 

metals as well as nutrient recycling. Resuspension events are less likely in deepwater environments 

(Caetano et al., 2003; Fanning et al., 1982).

Several studies have addressed offshore water and sediment quality in deep waters. Water 

at depths >1,400 m (4,593 ft) is relatively homogeneous with respect to temperature, salinity, and 

oxygen (Nowlin,1972; Pequegnat, 1983; Gallaway et al., 1988; Jochens et al., 2005). Limited 

analyses of trace metals and hydrocarbons for the water column and sediments exist (Trefry, 1981; 

Gallaway et al., 1988). Continental Shelf Associates, Inc. completed an Agency-funded field study 

of four drilling sites located in water depths of 1,033-1,125 m (3,389-3,691 ft) (CSA, 2006). The 

sampling design called for before and after exploratory or development drilling and captured the 

drilling-related changes that occur in sediments and sediment pore water. Chemical impacts of 

drilling were detected at all four sites. Impacts noted within the near-field zone included elevated 

barium, synthetic-based fluids, total organic carbon concentrations, and low sediment oxygen levels. 

One of the study locations was Viosca Knoll Block 916, which was considered to be relatively 
Impact-Producing Factors and Scenario 3-205

pristine prior to drilling. No drilling had ever been performed at Viosca Knoll Block 916, and the 

closest drilling activity had occurred 1.4 mi (2.3 km) north-northwest 2 years prior to the study. The 

site was located at a water depth of 1,125 m (3,691 ft) and 70 mi (120 km) from the mouth of the 

Mississippi River. At this relatively pristine location, mean concentrations of sediment barium 

increased by approximately 30-fold at near-field stations following exploratory drilling (from 0.108% 

to 3.32%). As well, mean concentrations of sediment mercury and total PAHs increased in the nearfield. At this site, sediment cadmium concentrations did not change substantially following 

exploratory drilling.

Several studies have assessed the occurrence and distribution of hydrocarbons in sediments 

since the Deepwater Horizon explosion, oil spill, and spill response in 2010 from Mississippi Canyon 

Block 252. Montagna et al. (2013) reported results of monitoring cruises conducted in the fall of 

2010 to measure potential impacts on two soft bottom benthic invertebrate groups, i.e., macrofauna 

and meiofauna. The most severe relative reduction of faunal abundance and diversity extended to 

3 km (2 mi) from the wellhead in all directions, covering an area of 24 km2 (9 mi2

). Moderate impacts 

were observed up to 17 km (11 mi) toward the southwest and 8.5 km (5.3 mi) toward the northeast 

of the wellhead, covering an area of 148 km2 (57 mi2

). Benthic effects were correlated to 

hydrocarbon concentrations and distance from the wellhead but not distance to natural hydrocarbon 

seeps.

A study by Valentine et al. (2014) used the concentration of the marker compound hopane in 

more than 3,000 sediment samples from 534 locations to evaluate the extent of oil on the seafloor. 

The pattern of contamination was described as similar to a “bathtub ring” formed from an oil-rich 

layer of water impinging laterally on the continental slope at a depth of about 900-1,300 m 

(2,953-4,265 ft). A secondary “fallout plume” from the oil-rich layer was reported to impact a zone of 

sediments at a depth of about 1,300-1,700 m (4,265-5,577 ft). The combined areas of impact were 

estimated to span 3,200 km2 (1,236 mi2

). Based on the horizontal and vertical distribution of hopane 

in the sediments, the authors concluded that the contamination was consistent with the recent 

Deepwater Horizon explosion and oil spill as the source and not natural ongoing seeps. 

Calculations presented in the study indicate that oil in the “bathtub ring” represents 4-31 percent of 

the approximately 2 MMbbl of oil estimated to be sequestered in the oil-rich layer of water at depths 

of 1,000-1,300 m (3,287-4,265 ft).

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 PAH concentrations peaked in samples near Pensacola, Florida, and 

Galveston, Texas.

CHAPTER 4 

DESCRIPTION OF THE AFFECTED ENVIRONMENT AND IMPACT 

ANALYSIS

Description of the Affected Environment and Impact Analysis 4-3 

What’s in This Chapter

• Chapter 4 describes the affected environment and potential environmental consequences 

of a single proposed lease sale.

• Resources analyzed are as follows:

– Air Quality

– Water Quality

– Coastal Habitats (Estuarine Systems, 

and Coastal Barrier Beaches and 

Associated Dunes)

– Deepwater Benthic Communities

– Sargassum and Associated 

Communities

– Live Bottom Habitats (Topographic 

Features, and Pinnacles and 

Low-Relief Features)

– Fishes and Invertebrate Resources

– Birds

– Protective Species (Marine Mammals, 

Sea Turtles, Beach Mice, Protected 

Birds, and Protected Corals)

– Commercial Fisheries

– Recreational Fishing

– Recreational Resources

– Archaeological Resources

– Socioeconomic Issues (Land Use and 

Coastal Infrastructure, Economic 

Factors, and Social Factors, Including 

Environmental Justice)

• Impact-producing factors and impact-level definitions are identified for each resource.

• The analyses of environmental consequences consider the potential impacts from routine 

activities, accidental events, and cumulative impacts; and incomplete or unavailable 

information.

• Other analyses in this chapter include the following:

– Unavoidable Adverse Impacts of a Proposed Action

– Irreversible and Irretrievable Commitment of Resources

– Relationship Between the Short-term Use of Man’s Environment and the Maintenance 

and Enhancement of Long-term Productivity

4 DESCRIPTION OF THE AFFECTED ENVIRONMENT AND IMPACT 

ANALYSIS

As discussed in Chapter 1.3, BOEM makes individual decisions on whether and how to 

proceed with each lease sale pursuant to the OCSLA’s staged leasing process. Additional NEPA 

reviews (e.g., a Determination of NEPA Adequacy, an EA or, if determined necessary, a 

Supplemental EIS) will be conducted prior to subsequent lease sale decisions. Therefore, 

Chapter 4 describes the environment that would potentially be affected by a single lease sale or the 

alternatives. The environmental resources include air and water quality; coastal environments; 

deepwater habitats; Sargassum and associated communities; live bottom habitats; fishes and 

invertebrate resources; birds; protected species (including marine mammals, sea turtles, beach 

mice, birds, fishes, and corals); commercial and recreational fishing; recreational resources; 

archaeological resources; coastal infrastructure and land use ; economics; and social factors 

(including environmental justice). Also, this chapter describes the potential impacts of routine 

activities, reasonably foreseeable accidental events, and cumulative impacts caused by a proposed 

lease sale and the alternatives on these resources.

Analysts concentrated on providing a focused analysis, using illustrations to communicate 

key concepts, and including more detailed, technical information in supporting appendices. 

Furthermore, supporting technical information in previous NEPA reviews have been developed as 

white papers and are summarized and incorporated by reference as appropriate. These white 
4-4 Gulf of Mexico Multisale EIS

papers include the OCS Regulatory Framework (Cameron and Matthews, 2016), Catastrophic Spill 

Event Analysis (USDOI, BOEM, 2016c) and Essential Fish Habitat Assessment (USDOI, BOEM, 

2016d).

This Multisale EIS also tiers from and uses information contained in the Outer Continental 

Shelf Oil and Gas Leasing Program: 2017-2022, Programmatic Environmental Impact Statement

(Five-Year Program EIS; USDOI, BOEM, 2016b). Programmatic aspects of climate change relative 

to the environmental baseline for the Gulf of Mexico OCS Program are discussed within each 

resource and in the Five-Year Programmatic EIS.

This Multisale EIS was prepared with consideration of potential changes to or new 

information about the baseline conditions of the physical, biological, and socioeconomic resources. 

Past events such as Hurricanes Katrina and Rita and the Deepwater Horizon explosion, oil spill, and 

response have 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 currently be 

known and some could take years to fully develop (refer to the “Incomplete or Unavailable 

Information” section below). The analyses of impacts from the Deepwater Horizon explosion, oil 

spill, and response on the physical, biological, and socioeconomic resources are based on credible 

scientific information that was publicly available at the time this document 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 subject-matter 

experts’ technical knowledge and experience. However, BOEM and the Deepwater Horizon Natural 

Resource Damage Assessment (NRDA) Trustee Council continue to study, measure, and interpret 

impacts arising out of that spill. Thus, there are instances in which BOEM is faced with incomplete 

or unavailable information (see below) that may be relevant to evaluating reasonably foreseeable 

significant adverse impacts on the human environment.

Organization

This chapter is organized by groups of resources. The chapter is divided into the physical 

factors (air and water quality), biological factors (habitat resources followed by the fauna that are 

found in or utilize these habitats), and finally land use and the social environment.

• Air Quality (Chapter 4.1) 

• Water Quality (Chapter 4.2) 

• Habitat Resources

− Coastal Habitats (Chapter 4.3) 

− Deepwater Benthic Communities (Chapter 4.4) 
Description of the Affected Environment and Impact Analysis 4-5 

− Sargassum and Associated Communities (Chapter 4.5) 

− Live Bottom Habitats (Chapter 4.6) 

• Faunal Resources

− Fish and Invertebrate Resources (Chapter 4.7) 

− Birds (Chapter 4.8) 

− Protected Species (Chapter 4.9) 

• Social Environment

− Commercial Fisheries (Chapter 4.10) 

− Recreational Fishing (Chapter 4.11) 

− Recreational Resources (Chapter 4.12) 

− Archaeological Resources (Chapter 4.13) 

− Human Resources and Land Use (Chapter 4.14) 

The habitat resource chapters focus on the impact-producing factors that would affect their 

environment while the other chapters concentrate on the biological effects of impact-producing 

factors on fauna and human resources. To decrease repetition, the habitat information is generally 

not restated in the fauna chapters and vice versa. Each resource chapter includes a description of 

the affected environment and an analysis of the potential environmental consequences of the 

alternatives. 

Environmental Consequences

The environmental consequences in each resource section include an analysis of applicable 

impact-producing factors from routine activities, accidental events, and cumulative impacts, and also 

discuss incomplete or unavailable information that would occur under any of the action alternatives 

(A, B, C, and D). The potential impacts as a result of these impact-producing factors are then based 

on the level of activity and the geographic area for each alternative. The impact level conclusions 

reached in each resource area consider the applicable impact-producing factors, the level of activity, 

and geographic area of each alternative.

Under all four action alternatives, postlease activities would be reviewed on a case-by-case 

basis and the applicable commonly applied mitigating measures (refer to Appendix B) would be 

identified during site-specific reviews of plans and permits. This avoids excessive replication of 

discussion of similar if not identical impacts throughout the entire document, allowing the reader to 

focus on the differences between the alternatives.
4-6 Gulf of Mexico Multisale EIS

Routine Activities

The types of routine activities that could occur from all operations as a result of a single 

lease sale are described in Chapter 3.1. The major types of routine activities include geological and 

geophysical surveys; exploration, development, and production drilling; infrastructure emplacement 

and presence; transportation, including pipelines, vessels, and helicopters; discharges and wastes; 

decommissioning and removal; coastal infrastructure; air emissions; noise; and safety issues. The 

time period for postlease activities related to a single lease sale is 50 years.

Accidental Events

A summary of the information on accidental events that are reasonably foreseeable from all 

operations conducted under the OCS Program, as well as information on the number and sizes of 

spills from non-OCS sources is provided in Chapter 3.2. The types of accidental events that could 

reasonably be expected as a result of postlease activities include oil spills, losses of well control, 

accidental air emissions, pipeline failures, vessel and helicopter collisions, chemical and drilling-fluid 

spills, and spill response as a result of a proposed lease sale.

Cumulative Impacts

The cumulative analysis considers impacts to physical, biological, and socioeconomic 

resources that may result from the incremental impact of a proposed lease sale when added to all 

past, present, and reasonably foreseeable future human activities. However, most resources 

consider the past and present cumulative impacts as part of the baseline environmental conditions, 

and they are covered where relevant in the affected resource description. It is reasonably 

foreseeable to assume that lease sales would continue to occur, as they have historically, for many 

years to come in the Gulf of Mexico region, based on resource availability, existing infrastructure, 

and projected time lapses required for any other major energy sources to come online. However, 

the level of activities (exploration wells, production wells, and pipelines) becomes more speculative 

as time is projected further into the future. The causes for this are uncertainty in long-term oil price 

forecasts, resource potential, cost of development, and drill rig availability versus the amount of 

acreage leased from a lease sale. Furthermore, OCSLA provides for phased decisionmaking, each 

of which is a decision subject to NEPA. The OCSLA stages include the Five-Year Program stage to 

identify a schedule of leases over the period; the lease sale stage; the exploration stage; the 

development and production stage; and ultimately decisions on how a lessee may proceed with 

decommissioning. These reviews require consideration of cumulative impacts that would factor in 

changing environmental baselines, oil and gas price forecasts, and technology advancements, 

among others. Additionally, even though continued consumer demand is likely, new advances in 

technology (both on upstream development and production ends and downstream user ends) can 

potentially change the level of projected activities and how they are conducted. These could further 

minimize environmental risks. Technology advancements and organizational effectiveness could 

also further reduce projected air emissions, wastewater quantities, and other impact producing 

factors such as helicopter and vessel trips and accidental events.
Description of the Affected Environment and Impact Analysis 4-7 

Therefore, cumulative impact assessment for this Multisale EIS considers existing 

environmental baseline conditions, past OCS and non-OCS activities in the GOM, projected future 

activities as a result of past lease sales, 50 years of incremental projected activities as a result of the 

proposed lease sales during this Five-Year Program, and reasonably assumes projected activities 

for future lease sales based on current trends. Non-OCS oil- and gas-related activities include, but 

are not limited to, import tankering; marine transportation; State oil and gas activity; recreational, 

commercial, and military vessel traffic; offshore liquefied natural gas activity; recreational and 

commercial fishing; onshore development; and natural processes. The time period for reasonably 

foreseeable future actions are dependent upon the nature of each resource and are therefore 

defined in each resource chapter. The types of cumulative activities that could occur are described 

in Chapter 3.3. 

Incomplete or Unavailable Information

Throughout this chapter, where information was incomplete or unavailable, BOEM complied 

with its obligations under NEPA to determine if the information was relevant to reasonably 

foreseeable significant adverse impacts; if so, whether it was essential to a reasoned choice among 

alternatives; and, if it was essential, whether it can be obtained and whether the cost of obtaining the 

information is exorbitant, as well as whether scientifically credible information using generally 

accepted scientific methodologies can be applied in its place (40 CFR § 1502.22).

The most notable incomplete or unavailable information relates to some aspects of the 

effects from the Deepwater Horizon explosion, oil spill, and response. Credible scientific data 

regarding the potential short-term and long-term impacts from the Deepwater Horizon explosion, oil 

spill, and response on some GOM resources are becoming available but remain incomplete at this 

time, and it could be many years before this information becomes available. The Deepwater Horizon 

NRDA Trustee Council has released the Deepwater Horizon Oil Spill Draft Programmatic Damage 

Assessment and Restoration Plan and Draft Programmatic Environmental Impact Statement. 

However, the information collected during the NRDA process that the draft assessment, plan, and 

EIS used as a basis for their determinations are not yet publicly available (e.g., NRDA technical 

working group reports). The final plan may address much of what has been currently unavailable 

with regard to impacts to the environment from the Deepwater Horizon explosion, oil spill, and 

response. There remains information being developed through the NRDA process, but it is not yet 

available as a final report. Nonetheless, BOEM’s subject-matter experts acquired and used newly 

available, scientifically credible information; determined that other additional information was not 

available absent exorbitant expenditures or could not be obtained regardless of cost in a timely 

manner; and where gaps remained, exercised their best professional judgment to extrapolate 

baseline conditions and impact analyses using accepted methodologies based on credible 

information. 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 it can make an informed decision at this time without this incomplete or unavailable 

information. BOEM’s subject-matter experts have applied other scientifically credible information 

using accepted theoretical approaches and research methods, such as information on related or 
4-8 Gulf of Mexico Multisale EIS

surrogate species. 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.

Furthermore, BOEM has considered the reasonably foreseeable impacts of a low-probability 

catastrophic oil spill in a white paper. These types of events, such as the one that resulted from the 

Deepwater Horizon explosion, are not reasonably expected to occur and therefore are not part of a 

proposed action. BOEM has prepared the Catastrophic Spill Event Analysis white paper, which 

provides a summary of existing credible scientific evidence related to this issue and BOEM’s 

evaluation of the potential impacts to the physical, biological, and socioeconomic resources and 

conditions based upon theoretical approaches or research methods generally accepted in the 

scientific community (USDOI, BOEM, 2016c). The white paper was included in previous lease sale 

EISs as an appendix. To avoid repetition and redundancies, the white paper is incorporated by 

reference and is publicly available on BOEM’s website at http://www.boem.gov/nepaprocess/. 

BOEM updated the analysis in the white paper and will update it again should new information 

become available relevant to the reasonably foreseeable impacts of a catastrophic spill event.

Impact Levels

It must be emphasized that, in arriving at the overall conclusions for certain environmental 

resources (e.g., birds, fisheries, and wetlands) for each alternative, the conclusions are based on 

potential impacts to the resources or species population as a whole, not to individuals, small groups 

of animals, or small areas of habitat. Each resource topic discussion includes a threshold effects 

determination and includes a resource-specific definition of impact level. Additionally, potential 

beneficial effects of a proposed action have also been considered and identified in individual 

resource chapters. For example, implementation of a proposed lease sale is anticipated to have 

beneficial impacts in the Area of Interest for economics due to the direct and indirect spending 

associated with the oil and gas industry. For this Multisale EIS, effects thresholds are defined using 

four categories of significance.

• Negligible – Impacts may or may not cause observable changes to natural 

conditions; regardless, they do not reduce the integrity of a resource.

• Minor – Impacts cause observable and short-term changes to natural conditions 

but they do not reduce the integrity of a resource.

• Moderate – Impacts cause observable and short-term changes to natural 

conditions and/or they reduce the integrity of a resource.

• Major – Impacts cause observable and long-term changes to natural conditions 

and they reduce the integrity of a resource.

The conclusions developed by BOEM’s subject-matter experts regarding the potential effects 

of a proposed lease sale for most resources are necessarily qualitative in nature; however, they are 

based on the expert opinion and judgment of the highly trained subject-matter experts. Staff 
Description of the Affected Environment and Impact Analysis 4-9 

approach this effort utilizing credible scientific information and apply it to the subject resources using 

accepted methodologies. It is important to note that, barring another catastrophic oil spill, which is a 

low-probability accidental event not expected to occur and therefore not part of a proposed action, 

the adverse impacts associated with a proposed lease sale are expected to be small, and beneficial 

impacts are projected as well for certain activities and species. This is because of BOEM’s potential 

use of lease sale stipulations and mitigations, site-specific mitigations that may become conditions of 

plan or permit approval at the postlease stage, and mitigations required by other State and Federal 

agencies that help to reduce or minimize many of the impacts. Over the years, a suite of lease 

stipulations and mitigating measures has been developed to eliminate or ameliorate potential 

environmental effects, where implemented. BOEM’s primary mitigative method is the avoidance of 

impacts, which are primarily implemented during approval of postlease activities. In many instances, 

these were developed in coordination with other natural resource agencies such as the NMFS and 

FWS. Informal and formal consultation with other Federal agencies and affected States, and 

commenting opportunities for the public are implemented to assist in the development of the 

information and analyses in this Multisale EIS. Specifically, information requests soliciting input on 

the proposed lease sales were issued during scoping for this Multisale EIS (refer to Chapter 5).

Lease sale stipulations considered for a proposed lease sale may include the Topographic 

Features Stipulation; Live Bottom (Pinnacle Trend) Stipulation; Military Areas Stipulation; Evacuation 

Stipulation; Coordination Stipulation; Blocks South of Baldwin County, Alabama, Stipulation; 

Protected Species Stipulation; United Nations Convention on the Law of the Sea Royalty Payment 

Stipulation; Below Seabed Operations 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 (Transboundary Stipulation). Site-specific postlease 

mitigations may include buffer zones and avoidance criteria to protect sensitive resources such as 

areas of deepwater benthic communities, topographic features, and historic shipwrecks. Mitigations 

may also be required by other agencies (i.e., the U.S. Army Corps of Engineers and State CZM 

agencies) to avoid or reduce impacts from OCS oil- and gas-related activities, e.g., boring under 

beach shorelines and the rerouting of pipelines to reduce or eliminate impacts from OCS pipelines 

that make landfall. These mitigations and their potential effect on reducing or eliminating impacts 

from a proposed lease sale are analyzed in this chapter.

Analytical Approach

The analyses of potential impacts to the wide variety of physical, environmental, and 

socioeconomic resources in the vast area of the GOM and adjacent coastal areas is very complex. 

Analysis of the various alternatives considers impact-producing factors (described in detail in 

Chapter 3) within a distinct framework that includes frequency, duration, and geographic extent. 

Frequency (whether rare, intermittent, or continuous) refers to how often the factor occurs over the 

entire analysis period of 50 years for routine activities and accidental events. Duration refers to how 

long the factor lasts from less than a year to many years. Geographic extent covers what areas are 

affected, and depending on the factor, how large of an area is affected.
4-10 Gulf of Mexico Multisale EIS

Specialized education, experience, and technical knowledge are required of the subjectmatter experts, as well as familiarity with the numerous impact-producing factors associated with 

OCS oil- and gas-related activities and other activities that can cause cumulative impacts in the area 

to conduct this analysis. 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), ESA, Marine Mammal Protection Act, Magnuson-Stevens Fishery Conservation and 

Management Act, and others are also required to conduct this analysis. In order to accomplish this 

task, BOEM has assembled an interdisciplinary team with many years of collective experience. The 

vast majority of this team has advanced degrees with a high level of knowledge related to the 

particular resources discussed in this chapter. This team prepares the input to BOEM’s lease sale 

EISs and a variety of subsequent postlease NEPA reviews, and is also involved with ESA, EFH 

Assessment, and CZMA consultations. In addition, this same staff is also directly involved with the 

development of studies conducted by BOEM’s Environmental Studies Program. The results of these 

studies feed directly into the Bureau of Ocean Energy Management’s NEPA analyses.

For this Multisale EIS, a set of assumptions and a scenario were developed along with 

descriptions of impact-producing factors that could occur from routine OCS oil- and gas-related 

activities, including accidental events. These provide a framework for the analyses of potential 

impacts of the OCS oil- and gas-related activity in the GOM. This information is discussed in detail 

in Chapter 3. High-level summaries of the geographic area and level of forecasted activities for 

each alternative are provided below. Using this information, the interdisciplinary team applies 

knowledge and experience to conduct analyses of the potential effects of a proposed lease sale on 

assigned resources.

Alternative A could potentially result in 1.2-3.8 percent of the forecasted cumulative OCS oil 

and gas activity in the Gulf of Mexico and would occur in the WPA, CPA, and EPA portions of the 

proposed lease sale area. Most of the activity (up to 83%) of a proposed lease sale under 

Alternative A is expected to occur in the CPA and EPA portions of the proposed lease sale area, 

while up to 19 percent of the activity could occur in the WPA portion of the proposed lease sale area. 

Approximately 72.5 million acres (78.6%) of the regionwide lease sale area would be available for 

lease under this alternative.

Alternative B could potentially result in 2.0-3.6 percent of the forecasted cumulative OCS oil 

and gas activity in the Gulf of Mexico, or a slightly smaller amount of activity than proposed for 

Alternative A, and would be located geographically in the CPA and EPA portions of the proposed 

lease sale area. Approximately 48.9 million acres (53%) of the regionwide lease sale area would be 

available for lease. While all of the leases issued under this alternative would occur in the CPA and 

EPA portions of the proposed lease sale area, activities such as vessel support and pipeline or 

coastal infrastructure could occur in the WPA portion of the proposed lease sale area.

Alternative C could potentially result in 0.35-0.6 percent of the forecasted cumulative OCS oil 

and gas activity in the Gulf of Mexico, which is much smaller than either Alternative A or B. 

Approximately 23.6 million acres (25.6%) of the regionwide lease sale area would be available for 
Description of the Affected Environment and Impact Analysis 4-11

lease. While all of the leases issued under this alternative would occur in the WPA portion of the 

proposed lease sale area, activities such as vessel support and pipeline or coastal infrastructure 

could occur in the CPA/EPA portion of the proposed lease sale area.

Under Alternative D, the number of available unleased blocks subject to the Topographic 

Features, Live Bottom (Pinnacle Trend), and Blocks South of Baldwin County, Alabama, Stipulations 

is small compared with the number of unleased blocks being offered under Alternatives A, B, or C. 

Therefore, the activity level that can be expected for Alternative D is similar to Alternative A, B, or C, 

as applicable.

Under Alternative E, there would be no routine activities or accidental events as part of a 

proposed lease sale. Therefore, there would be no associated impacts resulting from a proposed 

lease sale. Cancellation of a proposed lease sale, however, would not stop all OCS oil- and gasrelated activities. Activities related to previously issued leases and permits (as well as those that 

may be issued in the future under separate decision) related to the OCS oil and gas program would 

continue and could have impacts similar to those described in each resource section. However, no 

new activities related to a proposed lease sale would proceed and, therefore, those additional 

impacts would be avoided.

In summary, this chapter has thoroughly examined the existing credible scientific evidence 

that is relevant to evaluating the reasonably foreseeable significant impacts of a proposed lease sale 

on the human environment. All reasonably foreseeable impacts, including beneficial ones, were 

considered. Impacts that could have catastrophic consequences, even if their probability of 

occurrence is low, not reasonably expected, and not part of a proposed action are considered in the 

Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2016c). Throughout this chapter, 

where information was incomplete or unavailable, BOEM complied with its obligations under NEPA 

to determine if the information was relevant to reasonably foreseeable significant adverse impacts; if 

so, whether it was essential to a reasoned choice among alternatives; and, if it was essential, 

whether it can be obtained and whether the cost of obtaining the information is exorbitant, as well as 

whether credible scientific information applied using generally accepted scientific methodologies can 

be used in its place (40 CFR § 1502.22). BOEM has made conscientious efforts to comply with the 

spirit and intent of NEPA and to be comprehensive in its analyses of potential environmental 

impacts. 

4.1 AIR QUALITY

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

with a GOM proposed lease sale and its incremental contribution to the cumulative impacts are 

presented in this chapter. BOEM specifically addresses the air quality impacts of OCS oil and gas 

exploration, development, and production, as well as the non-OCS oil- and gas-related activities 

sources. These OCS oil- and gas-related emissions sources are related to drilling and associated 

vessel support, production and the connected action of vessel support, flaring and venting, 

decommissioning, fugitive emissions, and oil spills, while the non-OCS oil- and gas-related 
4-12 Gulf of Mexico Multisale EIS

emissions include State oil and gas programs, onshore industrial and transportation sources, and 

natural events. Since the primary National Ambient Air Quality Standards (NAAQS) are designed to 

protect human health, BOEM focuses on the impact of these activities on the States, where there 

are permanent human populations. The full analyses, including the air quality impacts to the 

State/seaward boundary, will be included in future EIS documents since studies examining the 

impact to the State/seaward boundary are currently in progress.

The approach to discuss the greatest potential impact-producing factors from OCS oil and 

gas exploration, development, and production (Table 4-1) in this Multisale EIS is based on the 

results found in the Year 2011 Gulfwide Emission Inventory Study (GWEI) (Wilson et al., 2014) and 

on the changes in regulations as a result of the 2010 Deepwater Horizon explosion, oil spill, and 

response. The Year 2011 GWEI study combines the activity data with the most recent emission 

factors published by the USEPA and estimation methods to develop the criteria pollutants and 

greenhouse gas emission inventories. The pollutants covered in the inventory are the criteria 

pollutants, i.e., carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM2.5 and PM10), 

sulfur dioxide (SO2), and volatile organic compounds (VOC); as well as the major greenhouse gases, 

i.e., carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The GWEI study groups the 

emissions into two very broad source categories: OCS oil/gas production sources, which includes 

both non-platform (drilling) and platform (production) sources; and non-OCS oil/gas production 

sources, which includes the sources completely unrelated to offshore oil and gas such as 

commercial vessel traffic. The GWEI study shows that during the exploration stage, most OCS 

emissions are from non-platform sources and include fuel combustion from the equipment used on a 

drilling rig or from fuel usage by a support vessel; during the development stage, most OCS 

emissions are also from non-platform emissions and include fuel usage by support or survey vessels 

to lay pipelines, install facilities, or map geologic formations and seismic properties; and during the 

production stage, most emissions are from platform emission sources.

Table 4-1. Air Quality Impact-Producing Factors.

Air Quality Magnitude of Potential Impact

Impact-Producing Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Drilling Minor Minor Minor Minor None

Production Minor Minor Minor Minor None

Vessel Support during 

Drilling and Production Minor Minor Minor Minor None 

Routine Flaring and 

Venting Minor Minor Minor Minor None

Greenhouse Gases Minor Minor Minor Minor None

Decommissioning Minor Minor Minor Minor None

Fugitive Emissions Minor Minor Minor Minor None
Description of the Affected Environment and Impact Analysis 4-13

Air Quality Magnitude of Potential Impact

Impact-Producing Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Accidental Impacts

Emergency Flaring and 

Venting Minor Minor Minor Minor None

Oil Spills Minor Minor Minor Minor None

Cumulative Impacts

OCS Oil and Gas Minor Minor Minor Minor Neglible

Non-OCS Oil and Gas Minor Minor Minor Minor Neglible 

In order to assess the impact-producing factors from OCS oil- and gas-related activities from 

routine activities and accidental events, BOEM used data from the Year 2011 GWEI study, which is 

the most recent detailed emissions inventory.

Impact-Level Definitions

The following impact categories and definitions are used:

• Negligible – No measurable impact(s).

• Minor – Most impacts on the affected resource could be avoided with proper 

mitigation; if impacts occur, the affected resource would recover completely 

without mitigation once the impacting stressor is eliminated.

• Moderate – Impacts on the affected resource are unavoidable. The viability of 

the affected resource is not threatened although some impacts may be 

irreversible, or the affected resource would recover completely if proper 

mitigation is applied or proper remedial action is taken once the impacting 

stressor is eliminated.

• Major – Impacts on the affected resource are unavoidable. The viability of the 

affected resource may be threatened although some impacts may be irreversible, 

and the affected resource would not fully recover even if proper mitigation is 

applied or remedial action is implemented once the impacting stressor is 

eliminated.

On August 26, 2014, BOEM contracted with Eastern Research Group, Incorporated and its 

team members (i.e., ENVIRON International Corporation and Alpine Geophysics, LLC) to complete 

an air quality modeling study in the GOM region. The “Air Quality Modeling in the Gulf of Mexico 

Region” study is anticipated to be available July 2016. Under this contract, photochemical and 

dispersion air quality modeling would be conducted in the GOM region to assess the impacts of OCS 

oil- and gas-related development to nearby States as required under the OCSLA. For air quality 

analysis purposes, the GOM region’s OCS area of possible influence includes the States of Texas, 

Louisiana, Mississippi, Alabama, and Florida (Figure 4-1). In addition, the GOM region’s OCS area 
4-14 Gulf of Mexico Multisale EIS

includes the following Class I areas: the Breton National Wilderness Area in Louisiana; and the 

Bradwell Bay Wilderness Area, Chassahowitza National Wilderness Area, Everglades National Park, 

and St. Marks Wilderness Area in Florida. However, due to GOMESA, only the Breton National 

Wilderness Area is near the proposed lease sale area. The impact analysis determined by this 

modeling study will address current and proposed NAAQS.

Figure 4-1. Air Quality Areas of Influence (Texas, Louisiana, Mississippi, Alabama, and Florida) in 

the Gulf of Mexico OCS Region with the Class I Areas, Air Quality Jurisdiction Line, and 

OCS Lease Blocks. (USEPA Region 6 includes Gulf Coast States Texas and Louisiana; 

USEPA Region 4 includes Gulf Coast States Mississippi, Alabama, and Florida.)

4.1.1 Description of the Affected Environment

For this Multisale EIS analysis, the affected environment includes the WPA, CPA, and EPA. 

The area also includes the federally mandated national parks and wilderness areas where visibility is 

protected more stringently than under the NAAQS. Air quality impact analyses were conducted to 

assess the impacts of offshore oil- and gas-related activity to onshore areas of the Gulf Coast 

States. However, the potential impacts to be modeled at the State/seaward boundary of Gulf Coast 

States (3-9 nmi [3.45-10.36 mi; 5.56-16.67 km] from shore, depending on the State) will also be 

included in the full analyses and will be included in future EIS documents.

The Clean Air Act of 1970 established the NAAQS; the NAAQS include primary standards to 

protect public health and secondary standards to protect public welfare, including visibility and 

vegetation. The current NAAQS, shown in Table 4-2, address seven pollutants: carbon monoxide 

(CO); nitrogen dioxide (NO2); particle pollution as (PM2.5 and PM10); sulfur dioxide (SO2); lead (Pb); 

and ozone (O3). Since particle pollution is represented as particulate matter in the table, BOEM 
Description of the Affected Environment and Impact Analysis 4-15

uses particulate matter to refer to particle pollution. Particulate matter is presented as two 

categories according to size. Fine particulate matter is less than 2.5 μm in size (PM2.5), and coarse 

particulate matter is in the size range of 2.5-10 μm (PM10). Under the Clean Air Act, the USEPA is 

periodically required to review and, as appropriate, modify the criteria based on the latest scientific 

knowledge. Several revisions to the NAAQS have occurred in the past few years as more is 

understood about the effects of the pollutants.

The Clean Air Act Amendments of 1977 specifies requirements to preserve air quality in 

national parks, national wilderness areas, national monuments, and national seashores. The 

amendments establish Class I, II, and III areas, where ambient concentrations of particulate matter, 

nitrogen dioxide, and sulfur dioxide are to be restricted. The restrictions are most severe in Class I 

areas and are progressively more lenient in Class II. All federally managed lands that are not 

Class I areas are Class II areas. Since Class I areas are most restrictive, Class I areas located in 

the GOM will be discussed in this Multisale EIS. The five Class I areas situated on the coast of the 

GOM are shown in Figure 4-1. Each of these Class I areas fall under the jurisdiction of a Federal 

Land Manager: the FWS has jurisdiction in the Breton National Wilderness Area, Chassahowitza 

National Wilderness Area, and St. Marks Wilderness Area; the NPS has jurisdiction in the 

Everglades National Park; and the U.S. Forest Service has jurisdiction in the Bradwell Bay 

Wilderness Area. These Federal Land Managers have responsibility for protecting wildlife, 

vegetation, visibility, and other sensitive resources that are called air-quality-related values in these 

areas. The Clean Air Act Amendments of 1990 gave air quality responsibility for the OCS waters in 

the Gulf of Mexico east of 87.5o W. longitude to the USEPA (which includes part of the CPA and all 

of the EPA), but BOEM retained air quality jurisdiction for OCS operations west of 87.5o W. longitude

(most of the CPA and all of the WPA) in the Gulf of Mexico. This separation of authority is depicted 

in Figure 4-1. The Clean Air Act Amendments of 1990 also established classification designations 

based on regional monitored levels of ambient air quality. These designations impose mandated 

timetables and other requirements necessary for attaining and maintaining healthful air quality in the 

U.S. based on the seriousness of the regional air quality problem. These designations are 

nonattainment, attainment, and unclassifiable. Nonattainment is any area that does not meet 

national primary or secondary ambient air quality standard for the pollutant. When measured 

concentrations of these regulated pollutants exceed the standards established by the NAAQS, the 

number of exceedances and the concentrations determine the nonattainment classification of an 

area. The Clean Air Act Amendments list five classifications of nonattainment status—marginal, 

moderate, serious, severe, and extreme. Attainment is any area that meets the national primary or 

secondary ambient air quality standard for the pollutant. Unclassifiable is any area that cannot be 

classified on the basis of available information as meeting or not meeting the national primary or 

secondary ambient air quality standard for the pollutant.
4-16 Gulf of Mexico Multisale EIS

Table 4-2. National Ambient Air Quality Standards.

Pollutant

(Final Rule Citation)

Primary/

Secondary

Averaging

Time Level Form

Carbon Monoxide (CO)

(Federal Register, 2011a) Primary

8-hour 9 ppm Not to be exceeded more than 

1-hour 35 ppm once per year

Lead (Pb)

(Federal Register, 2008b)

Primary and 

Secondary

Rolling 

3-month 

average

0.15 μg/m3(1) Not to be exceeded

Nitrogen Dioxide (NO2) 

(Federal Register, 2010a)

(Federal Register, 1996) 

Primary 1-hour 100 ppb 98th percentile, averaged over 

3 years

Primary and 

Secondary Annual 53 ppb(2) Annual mean

Ozone (O3) 

(Federal Register, 2015)

Primary and 

Secondary 8-hour 0.070 ppm(3)

Annual 4th-highest daily 

maximum 8-hour concentration, 

averaged over 3 years

Particle Pollution

(Federal Register, 

2013)

(Federal Register, 

2006b)

PM2.5

Primary Annual 12 μg/m3 Annual mean, averaged over 

3 years

Secondary Annual 15 μg/m3 Annual mean, averaged over 

3 years

Primary and 

Secondary 24-hour 35 μg/m3 98th percentile, averaged over 3 years

PM10

Primary and 

Secondary 24-hour 150 μg/m3

Not to be exceeded more than 

once per year on average over 

3 years

Sulfur Dioxide (SO2) 

(Federal Register, 2010b)

(Federal Register, 1973a)

Primary 1-hour 75 ppb(4)

99th percentile of 1-hour daily 

maximum concentrations, 

averaged over 3 years

Secondary 3-hour

3-hour

0.5 ppm

0.5 ppm

Not to be exceeded more than 

once per year

(1) The Final Rule was signed on October 15, 2008. The 1978 lead standard (1.5 μg/m3 as a quarterly 

average) remains in effect until 1 year after an area is designated for the 2008 standard. Areas 

designated nonattainment under the 1978 standard remain in effect until implementation plans are 

approved to attain or maintain the 2008 standard.

(2) The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for 

the purpose of clearer comparison to the 1-hour standard.

(3) The final rule was signed on October 1, 2015, and became effective on December 28, 2015. The 

previous (2008) O3 standards additionally remain in effect in some areas. Revocation of the previous 

(2008) O3 standards and transitioning to the current (2015) standards will be addressed in the 

implementation rule for the current standards.

(4) The Final Rule was signed on June 2, 2010. The 1971 annual and 24-hour SO2 standards were 

revoked in that same rulemaking. However, these standards remain in effect until 1 year after an 

area is designated for the 2010 standard, except in areas designated nonattainment for the 1971 

standards, where the 1971 standards remain in effect until implementation plans to attain or maintain 

the 2010 standard are approved.

Notes: PM – particulate matter; ppb – parts per billion; ppm – parts per million.

Source: USEPA, 2015d.
Description of the Affected Environment and Impact Analysis 4-17

Clean Air Act Amendments’ Classification Designation in the Gulf of Mexico Region

The Federal OCS waters are unclassifiable. The OCS areas are not classified because 

there is no regulatory provision for any classification in the Clean Air Act for waters outside of the 

boundaries of State waters. Only areas within State boundaries are to be classified as either 

attainment or nonattainment. In this Multisale EIS analysis, attainment and nonattainment status for 

the criteria pollutants (i.e., CO, NO2, PM2.5, PM10, SO2, O3, and Pb) include the coastal 

counties/parishes of Alabama, Florida, Louisiana, Mississippi, and Texas. The ozone nonattainment 

status discussed in this chapter represents the 2008 O3 standard since the USEPA has not 

designated nonattainment status for the 2015 O3 standard.

Attainment status for counties/parishes in the States of the GOM region is as follows: 

Alabama is attainment for all criteria pollutants except Pb; Florida is in attainment for all criteria 

pollutants except Pb and SO2; Louisiana is in attainment for all criteria pollutants except O3 and SO2; 

Mississippi is attainment for all criteria pollutants; and Texas is in attainment for all criteria pollutants 

except O3 and Pb.

Nonattainment status for counties/parishes in the States of the GOM region includes 

Alabama, Florida, Louisiana and Texas. In Alabama, the 2008 Pb standard has been exceeded, but 

a nonattainment status subclassification (i.e., marginal, moderate, serious, severe, and extreme) has 

yet to be assigned to this area in Pike County (USEPA, 2015a). In Florida, the 2008 Pb standard 

and the 2010 SO2 standard have been exceeded in Hillsboro County, but a nonattainment status 

subclassification has yet to be assigned to this area (USEPA, 2015b). Figure 4-2 shows the 

nonattainment status for the 2008 O3 standard in both Louisiana and Texas. Louisiana is in 

nonattainment for criteria pollutants O3 and SO2. In Louisiana, the 2008 8-hour O3 standard is 

classified as marginal in the following parishes: Ascension, East Baton Rouge, Iberville, Livingston, 

and West Baton Rouge; but the 2010 SO2 standard exceedance has yet to be subclassified in 

St. Bernard Parish (USEPA, 2015c). In Texas, the 2008 8-hour O3 standard is classified as marginal 

in the following coastal counties: Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, 

Montgomery, and Waller; but the 2008 Pb standard has yet to be subclassified in Collin County 

(USEPA, 2015d).
4-18 Gulf of Mexico Multisale EIS

Figure 4-2. Ozone Nonattainment Status in the Gulf of Mexico Region in Louisiana and Texas. 

(Note: This figure does not indicate the platform count, location, or emissions at the time 

of publication of this Multisale EIS.)

Emission Inventories

The Year 2011 GWEI study was completed with a goal to develop criteria pollutant and 

greenhouse gas emission inventories for all oil and gas production-related sources on the Gulf of 

Mexico OCS, including platform and non-platform sources as well as non-OCS oil- and gas-related 

emissions. This inventory includes all major oil and gas production platforms and non-platform 

sources under BOEM’s air quality jurisdiction on the Gulf of Mexico OCS. Platform sources include 

the following: amine units; boilers/heaters/burners; diesel engines; drilling equipment; combustion 

flares; fugitive sources; glycol dehydrators; losses from flashing; minor sources; mud degassing; 

natural gas engines; natural gas, diesel, and dual-fueled turbines; pneumatic pumps; pressure/level 

controllers; storage tanks; and cold vents. Non-platform sources, sources related to OCS oil and 

gas that do not occur from a stationary platform location, include the following: drilling rigs; 

pipelaying operations; support helicopters; support vessels; and survey vessels. Non-platform nonoil/gas production sources are unrelated to the OCS oil and gas industry and include the following: 

biogenic and geogenic sources; commercial fishing vessels; commercial marine vessels; LOOP; 

military vessels (Coast Guard/Navy); vessel lightering; and recreational vessels. Pollutants covered 

in the inventory are the criteria pollutants (i.e., CO, NOx, PM2.5, PM10, SO2, and VOC), as well as the 

major greenhouse gases (i.e., CO2, CH4, and N2O). The particulate matter emission estimates of 

PM2.5 and PM10 are similar; PM10 values being slightly higher. Therefore, PM10 values have been 
Description of the Affected Environment and Impact Analysis 4-19

used in figures in this chapter to represent particulate matter. Nitrogen dioxide, a NAAQS criteria 

pollutant, is one of a group of highly reactive gases known as NOx. In this inventory, nitrogen oxides 

(NOx) are stated as an equivalent mass of NO2; consequently, NOx is used instead of NO2. The 

VOCs are not a NAAQS criteria pollutant but are precursors to ozone formation. Lead (Pb), a 

NAAQS criteria pollutant, is not covered in this inventory due to the lack of credible emission factors 

available at the time this inventory was developed. However, Pb will be analyzed in the air quality 

modeling study.

Ozone (O3) is a NAAQS criteria pollutant but is not covered in this inventory. This inventory 

provides emission estimates for directly emitted pollutants. Ozone is not directly emitted into the air 

from OCS oil- and gas-related activities. Therefore, NOx and VOCs, which are precursors to ozone, 

are analyzed. Since ozone is formed by photochemical reactions of NOx and VOCs in the 

atmosphere, photochemical modeling would need to be conducted to determine ozone impacts. The 

air quality modeling study includes both photochemical and dispersion modeling, and it uses the 

2011 emission inventory to assess ozone impacts.

As previously stated, these emissions inventories are used in air quality modeling to 

determine the potential impacts of offshore sources to onshore areas. However, potential impacts 

modeled at the State/seaward boundary will be included in future EIS documents.

The figures below illustrate the NOx and VOC emissions from platform and non-platform 

sources. The emissions are shown across the CPA and WPA, where BOEM has air quality 

jurisdiction. Figure 4-3 shows the NOx emissions from platform sources. Figure 4-4 shows the NOx

emissions from non-platform sources. Figure 4-5 shows VOC emissions from platform sources, and 

Figure 4-6 shows VOC emissions from non-platform sources.

The Year 2011 GWEI total platform and non-platform criteria pollutants emissions and the 

total platform and non-platform greenhouse gas emissions results are depicted in Figures 4-7 

and 4-8, respectively. In both figures, the total emissions sources include three main categories: 

total non-OCS oil/gas production source emissions; total OCS oil/gas non-platform emissions; and 

total OCS oil/gas platform emissions. The results indicate that the total OCS oil and gas nonplatform sources emit the majority of criteria pollutants and greenhouse gases. However, the total 

non-OCS oil/gas production sources emit the majority of SO2, which is primarily released from 

commercial marine vessels; and the majority of CH4 and N2O, which are primarily released from 

biological sources. The total OCS oil/gas platform sources emit the majority of VOCs, which are 

primarily released by natural gas venting; the majority of CO, which is primarily released from natural 

gas engines; and the majority of CO2, which is primarily released from natural gas, diesel, and dualfuel turbines.
4-20 Gulf of Mexico Multisale EIS

Figure 4-3. 2011 Platform NOx Emissions (Wilson et al., 2014). (Note: This 

figure does not indicate the platform source count, location, or 

emissions at the time of publication of this Multisale EIS.)

Figure 4-4. 2011 Non-Platform NOx Emissions (Wilson et al., 2014). (Note: 

This figure does not indicate the non-platform source count, 

location, or emissions at the time of publication of this Multisale 

EIS.)
Description of the Affected Environment and Impact Analysis 4-21

Figure 4-5. 2011 Platform VOC Emissions (Wilson et al., 2014). (Note: This 

figure does not indicate the platform source count, location, or 

emissions at the time of publication of this Multisale EIS.)

Figure 4-6. 2011 Non-Platform VOC Emissions (Wilson et al., 2014). (Note: 

This figure does not indicate the non-platform source count, 

location, or emissions at the time of publication of this Multisale 

EIS.)
4-22 Gulf of Mexico Multisale EIS

Figure 4-7. Year 2011 Gulfwide Emission Inventory Results for Total Platform and 

Non-Platform Criteria Pollutant Emissions (TPY).

Figure 4-8. Year 2011 Gulfwide Emission Inventory Results for Total Platform and 

Non-Platform Greenhouse Gas Emissions (TPY). 

4.1.2 Environmental Consequences

The impact-producing factors and their potential impacts identified for routine activities, 

accidental events, cumulative impacts, and incomplete or available information would apply, in 

general, to Alternatives A-D. This analysis is then applied to each alternative based on the varying 

degrees of forecasted levels of activities by geographical area and water depth.
Description of the Affected Environment and Impact Analysis 4-23

Routine Activities

The following routine activities associated with a proposed lease sale would potentially affect 

air quality: drilling and production with associated vessel support; flaring and venting; fugitive 

emissions; greenhouse gases; and decommissioning (refer to Chapter 3.1.8 for a description of 

these routine activities). These routine activities result in pollutant emissions. Emissions of air 

pollutants from these activities would occur during exploration, development, production, and 

decommissioning activities. These activities may potentially affect the air quality at Bradwell Bay 

Wilderness Area, Breton National Wilderness Area, Chassahowitza National Wilderness Area, 

Everglades National Park, and St. Marks Wilderness Area during a 50-year analysis period.

Emissions during exploration are higher than emissions during development due to power 

requirements for drilling a deeper wellbore hole. During drilling, diesel engines are used to power 

the drilling (top drive) assembly, draw works, electrical generators, mud pumps, vessel propulsion 

(drillships and support vessels) and dynamic positioning (DP) systems of the drilling rig (if DP 

semisubmersible or DP drillship is used). Combustion of fuel to run the engines generates NAAQS 

criteria pollutants, VOCs, and greenhouse gases. More information about the pollutants that are 

generated by specific equipment and activities is available in the Year 2011 Gulfwide Emission 

Inventory Study (Wilson et al., 2014). As illustrated in Figure 3-2), during a 50-year analysis period, 

exploratory drilling mainly occurs during the first decade and development drilling extends 

throughout the first and second decade.

During production, pollutants emitted during routine activities may be combustion products of 

burning fuel to power pumps, compressors, or generators, or they may consist of fugitive VOCs, 

which escape from the uncombusted hydrocarbons. The platform emission sources include boilers, 

turbines, pneumatic pumps, diesel engines, combustion flares, fugitives, glycol dehydrators, natural 

gas engines, pressure/level controllers, storage tanks, cold vents, and others. As illustrated in 

Figure 3-2, during a 50-year analysis, most production occurs during the second and third decade.

During a 50-year analysis period, most decommissioning occurs during years 20-40. 

Decommissioning emissions are due mainly to engines on vessels used in the decommissioning 

process for propulsion, electrical power, and ancillary mechanical equipment and activities. These 

emissions include the following pollutants: CO, NO2, PM, SO2, CO2, CH4, N2O, and VOCs. 

During a 50-year analysis, greenhouse gas emissions would occur during the exploration, 

development, and production stages. The major greenhouse gases emitted from these activities 

include CO2, CH4, and N2O. Greenhouse gases are not NAAQS criteria pollutants and there is 

currently no ambient concentration standard for greenhouse gases. However, owners or operators 

of petroleum and natural gas facilities that emit 25,000 metric tons of carbon dioxide equivalent 

(CO2e) or more from process operations and stationary fuel combustion must report greenhouse gas 

emissions to the USEPA as required under the Greenhouse Gas Program. This reporting 

requirement includes platforms that fall under both BOEM’s air quality jurisdiction as well as 

USEPA’s air quality jurisdiction. The reporting requirement does not include emissions from offshore 
4-24 Gulf of Mexico Multisale EIS

drilling and exploration that is not conducted on production platforms. Since the GWEI studies 

include greenhouse gas emissions, calculated via the Gulfwide Offshore Activities Database System 

(GOADS), OCS operators can use the data to report their greenhouse gas emissions to the USEPA.

Routine flaring and venting emissions operations occur intermittently for short periods of time 

over the life of the lease. Flaring is the controlled burning of natural gas and is a common practice in 

oil and gas exploration, production, and processing operations. Flaring systems are also used to 

vent natural gas during well testing or during repair/installation of production equipment. The BSEE 

operating regulations at 30 CFR § 250.1160 provide for some limited volume, short-duration flaring, 

or venting of some natural gas volumes upon approval by BSEE. These operations may occur for 

short periods of time (typically 2-14 days) as part of unloading/testing operations that are necessary 

to remove potentially damaging completion fluids from the wellbore, to provide sufficient reservoir 

data for the operator to evaluate a reservoir and development options, and in emergency situations. 

The potential impacts from these emergency operations are described in the “Accidental Events” 

section below and in Chapter 3.2.3. 

Most of the hydrogen sulfide released to the air comes from natural sources such as 

swamps, bogs, and volcanoes. Hydrogen sulfide can also be released from industrial sources such 

as petroleum refineries, natural gas plants, kraft paper mills, manure treatment facilities, waste water 

treatment facilities, and tanneries. The concentration of hydrogen sulfide (H2S) occurring naturally in 

crude oil varies from formation to formation and even varies to some degree within the same 

reservoir. The natural gas in deepwater reservoirs has been mainly sweet (i.e., low in sulfur 

content), but the oil averages between 1 and 4 percent sulfur content by weight. By far, most of the 

documented production of sour gas (i.e., high sulfur content) lies within 150 km (93 mi) of the Breton 

National Wilderness Area Class I area. The BSEE regulations at 30 CFR § 250.490(f) describe 

safety precautions for employees operating in an H2S area. Hydrogen sulfide is a naturally occurring 

compound that is formed from the breakdown of organic matter in low oxygen environments. The 

effects of H2S depend on the magnitude, duration, and frequency of exposure, as well as

susceptibility of the individual organism or environment. The human nose is very sensitive and can 

detect extremely low levels of H2S. A rotten egg odor characterizes H2S at very low concentrations. 

However, prolonged exposure to low levels of H2S can cause skin irritation and olfactory paralysis. 

Therefore, relying on odor or sense of smell would not be a reliable warning signal to detect H2S 

presence. Short-term exposure to high concentrations of H2S can cause death. Portable monitors 

worn by workers, as well as visual and audible alarms and H2S sensors on platforms to activate 

when the presence of H2S is detected, can help to prevent loss of life. According to the NPS, Gulf 

Islands National Seashore visitors have complained about H2S odors. BOEM expects that 

concentrations at the park, resulting from OCS sources of H2S, to be at very low nuisance levels. 

The source of odors in the park may include releases from the local marsh muds or nearby State oil 

and gas activity. Therefore, several contributing factors could be responsible for the odors at Gulf 

Islands National Seashore.
Description of the Affected Environment and Impact Analysis 4-25

During the flaring of gas containing H2S, the gas entering the flare would largely combust to 

SO2. The contribution of flaring sour gas to SO2 is regulated in 30 CFR part 250 subpart K. The 

SO2 levels from routine flaring are evaluated as a part of the postlease plans review process.

Venting is the intentional release of unburned gases into the atmosphere in the course of oil 

and gas production operations. The primary sources of VOCs result from venting and evaporative 

losses that occur during the processing and transporting of natural gas and petroleum products. A 

more concentrated source of VOCs is the vents on glycol dehydrator units.

Fugitive emissions are gases that are not emitted through a stack or vent but instead leak or 

intermittently escape from pressurized equipment and sealed surfaces in various components of the 

facility. Fugitive emission sources include valves, flanges, connectors, pump seals, compressor 

seals, and pneumatic controllers. During a 50-year analysis period, fugitive emissions can occur 

during all phases of OCS oil- and gas-related activity. Fugitive emissions are mainly comprised of 

VOCs and methane (CH4).

Analysis of Routine Activities

The impacts on air quality from routine activities over the OCS and adjacent onshore areas 

would be minor. The impacts would vary in intensity based on the type and location of the activity. 

As a result of a proposed lease sale, more NAAQS criteria pollutants would be emitted to the 

affected environment, as described in Chapter 4.1.1. The OCS emissions in tons per year for the 

criteria pollutants and for the greenhouse gases from platform sources would resemble past 

emissions inventories and are indicated in Figures 4-9 and 4-10. The annual OCS emissions are 

based on the Year 2011 Gulfwide Emission Inventory Study (Wilson et al., 2014). Of the criteria 

pollutants, the major pollutant emitted is NOx, while PM10 is the least emitted pollutant. Of the 

greenhouse gases, the major pollutant emitted is CO2, while N2O is the least emitted pollutant. 

Combustion-intensive operations such as platform operations, well drilling, and service-vessel 

activities contribute mostly NOx and CO2; platform operations are also the major contributors of VOC 

emissions. As a result of a lease sale, multiple platforms would be installed on the leases, and 

platform construction emissions contribute appreciable amounts of all pollutants over the resulting 

lease sale’s 50-year analysis period. Emissions from a singular platform construction are temporary 

in nature and generally occur for a period of 3-4 months. Typical construction emissions result from 

the derrick barge placing the jacket and various modular components and from various service 

vessels supporting this operation. Drilling operations contribute considerable amounts of all 

pollutants. These emissions are temporary in nature and typically occur over a 90-day per well 

drilling period. Support vessels for OCS oil- and gas-related activities, as described in Chapter 

3.1.4.4, include emissions from NOx, CO, and CO2. These emissions are directly proportional to the 

number and type of OCS operations requiring support activities. Most emissions from these support 

activities occur during transit between the port and the offshore facilities; a smaller percentage of the 

emissions occur during idling at the platform. Platform and well emissions were calculated using the 

integration of projected well and platform activities over time.
4-26 Gulf of Mexico Multisale EIS

Figure 4-9. 2011 Criteria Pollutant Emissions (TPY) from Platform Sources.

Figure 4-10. 2011 Greenhouse Gases (TPY) from Platform Sources.

The total pollutant emissions per year from activities on a lease are not uniform. After a 

lease is obtained, various activities to utilize the lease ramp up. Non-platform emissions (drilling and 

associated vessel support) occur during the first decade and then taper down. After economically 

recoverable resources have been located, industry efforts turn to platform installation followed by 

production (platform emissions) and associated vessel support (non-platform emissions), with 

periodic maintenance episodes and additional side-track wells during roughly the second and third 

decade. After reaching a maximum, emissions would decrease during the third through fifth decade 

as wells are depleted and abandoned, platforms are removed, and service-vessel trips and other 

related activities are no longer needed.

Previous Modeling of Routine Activities

For past lease sale EIS analyses, BOEM used data from the Year 2008 Gulfwide Emission 

Inventory Study (Wilson et al., 2010) and the scenario from Chapter 3 of the 2012-2017 WPA/CPA 

Multisale EIS (USDOI, BOEM, 2012) to predict a range of impacts. The 2012-2017 WPA/CPA 
Description of the Affected Environment and Impact Analysis 4-27

Multisale EIS relied on modeling from the 2007-2012 WPA/CPA Multisale EIS (USDOI, BOEM, 

2007) because the scenarios projecting activity levels generating air emissions were similar.

Previous ozone modeling studies focused on the coastal areas of Louisiana extending 

eastward to Florida (Haney et al., 2008) and ozone levels in southeast Texas (Yarwood et al., 2004). 

These studies showed that the impacts of OCS emissions on onshore O3 levels were very small, 

with the maximum contribution of 1 ppb or less at Louisiana coastal locations when the standard was 

exceeded and with a maximum contribution of 0.2 ppb or less to Texas coastal areas exceeding the 

ozone NAAQS standard. Previous SO2 and NO2 annual modeling with the CALPUFF model 

revealed that none of the allowable SO2 or NO2 increments had been fully consumed, as shown in 

the table below (Wheeler et al., 2008).

Comparison of the Allowable SO2 or NO2 Increment 

in the Breton National Wilderness Area with the NAAQS

Increment Class I Area

(μg/m3)

Allowable Increment

(μg/m3)

3-hour SO2 1.7 25

24-hour SO2 1.18 5 

Maximum Annual SO2 1.07 2 

Maximum Annual NO2 0.1 2.5

The 1-hour NOx modeling performed by operators as part of the postlease approval process 

indicates concentrations less than the maximum increase allowed. Regulations, activity data 

reporting via the GOADS reporting requirement, and mitigation such as monitoring the performance 

of the sulfur recovery unit or the catalytic converter would ensure these levels stay within the 

NAAQS. 

Based on past studies (Wheeler et al., 2008), emissions of pollutants into the atmosphere 

from the activities associated with the OCS Program are not projected to have substantial effects on 

onshore air quality. Additionally, reductions in emissions have been achieved through the use of low 

sulfur fuels, catalytic reduction, and other efforts.

BOEM used data gathered during the Year 2008 and Year 2011 OCS emission inventories, 

along with a scenario or estimates of future production, to evaluate the potential effects of emissions. 

The scenario provided (1) the set of assumptions for and estimates of future activities, (2) the 

rationale for the scenario assumptions and estimates, and (3) the type, frequency, and quantity of 

emissions from offshore sources associated with a proposed lease sale. BOEM estimates the 

projected emissions that result from the activities on the lease from estimated emissions of 

equipment, such as diesel engines and generators, and the level of offshore activity projected in 

Chapter 3.1.8. Potential impacts resulting from all of the above routine activities based on Year 

2008 and Year 2011 OCS emission inventories, postlease 1-hour NOx modeling, and past studies 

are projected to be minor. Emissions of pollutants from activities associated with a regionwide 

proposed lease sale are not projected to have major effects on onshore air quality due to dilution 
4-28 Gulf of Mexico Multisale EIS

and diffusion of the pollutants over time and distance. The emission sources would not produce 

enough emissions to overcome the effects of wind and transport in a single area to cause 

deterioration of onshore air quality. The overall analysis of air quality demonstrates a minor impact 

on coastal areas. To develop a more robust analysis of emissions from OCS oil- and gas-related 

activities, as w ell as non-OCS oil- and gas-related activities, BOEM secured $2.5 million to fund a 

special study to obtain dispersion and photochemical modeling results (USDOI, BOEM, 2015). 

Since previous model runs, there have been new meteorological data and new NAAQS standards. 

The new study will compare previously used models as well as the new data and standards.

Accidental Events

BOEM determined the greatest impact factors from a reasonably foreseeable accidental 

event to be emergency flaring or venting, and oil spills. Accidental air emissions are described in

Chapter 3.2.3. 

The accidental release of hydrocarbons related to a proposed lease sale would result in the 

emission of air pollutants. The OCS accidents would include the release of oil, condensate, or 

natural gas or chemicals used offshore or pollutants from the burning of these products. The air 

pollutants include criteria NAAQS pollutants, volatile and semi-volatile organic compounds, hydrogen 

sulfide, and methane. These pollutants are discussed in Chapter 4.1.2 above. These accidental 

events may potentially affect the air quality at Bradwell Bay Wilderness Area, Breton National 

Wilderness Area, Chassahowitza National Wilderness Area, Everglades National Park, and 

St. Marks Wilderness Area during a 50-year analysis period.

Emergency Flaring

Emergency flaring may be conducted to manage excess natural gas during an accidental 

event such as damage to a pipeline that transports the gas to shore or a process upset. In the 

absence of safety flares, plants would be at a higher risk for fires and explosions. The flare is 

operated temporarily until the emergency situation is resolved. Flaring would result in the release of 

NOx emissions from the flare; SO2 emissions would be dependent on the sulfur content of the crude 

oil; and particulate matter from the flare would affect visibility.

The presence of H2S (Chapter 3.1.10.1) within formation fluids occurs sporadically 

throughout the Gulf of Mexico OCS and may be released during an accident. The BSEE regulations 

at 30 CFR part 250 subpart E and NTL 2009-G31 require health and safety precautions such as a 

Contingency Plan for special training, practice drills, strategically placed H2S sensors, alarms and 

flashing lights to indicate a release, and accessible protective-breathing equipment. Regulations 

also require equipment to have metallurgical properties to protect from cracking and corrosion and a 

flare system with a backup ignition source. While regulations are in place to reduce the risk of 

impacts from H2S and while no H2S-related deaths have occurred on the OCS, accidents involving 

high concentrations of H2S could result in deaths as well as environmental damage. 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 
Description of the Affected Environment and Impact Analysis 4-29

to 9 percent. Ignition of the blowout gas and subsequent fire would result in emissions of NOx, SOx, 

CO, VOCs, PM10, and PM2.5. The fire could also produce polycyclic aromatic hydrocarbons (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 Class I areas (i.e., 

National Wilderness Areas and National Parks) and other areas where visibility is of significant 

value.

Venting

Emergency venting may be necessary where flaring of the gas is not possible or in situations 

precluding the use of a flare gas system, such as insufficient hydrocarbon content in the gas stream 

to support combustion or a lack of sufficient gas pressure to allow it to enter the flare system. 

Venting produces mainly CH4 emissions.

Oil Spills

In the Gulf of Mexico, evaporation from an oil spill would result in concentrations of VOCs in 

the atmosphere, including chemicals that are classified as being hazardous. Benzene, toluene, 

ethylbenzene and xylene (BTEX) are a category of VOCs that occur naturally in crude oil, as well as 

during the process of making of gasoline and other fuels from crude oil. 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 decrease with distance as the layer of oil gets thinner. The lighter compounds 

of VOCs, such as BTEX, 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. In hazardous 

conditions, the Occupational Safety and Health Administration and USCG regulations require 

workers to use breathing protection. The hazard to workers can also be reduced by limiting 

exposure through limited work shifts, rotating workers in close vicinity of the spill site, and pointing 

vessels into the wind. While the spills analyzed as part of this Multisale EIS are significantly smaller 

than the catastrophic Deepwater Horizon explosion and oil spill, air samples collected during that 

event by individual offshore workers of British Petroleum (BP), the Occupational Safety and Health 

Administration (OSHA), and the USCG showed levels of BTEX that were mostly under detection 

levels. All samples had concentrations below the OSHA permissible exposure limits and the more 

stringent American Conference of Governmental Industrial Hygienists threshold limit values (U.S. 

Dept. of Labor, OSHA, 2010).

The VOC emissions that result from the evaporation of oil contribute to the formation of 

particulate matter (PM2.5) in the atmosphere (Brock et al., 2012). In addition, VOCs could cause an 

increase in ozone levels, especially if the release were to occur on a hot, sunny day with sufficient 
4-30 Gulf of Mexico Multisale EIS

concentrations of NOx present in the lower atmosphere. Effects to ozone concentrations would 

depend on distance of the proposed lease sale area from shore and the accidental spill size. If there 

were any effects to onshore ozone concentrations, they would likely be temporary in nature and last, 

at most, the length of time of the spill’s duration.

Removal and containment efforts to respond to an ongoing offshore spill would likely require 

multiple technologies, including source containment, mechanical cleanup, in-situ burning of the slick, 

and chemical dispersants (Chapter 3.2.7). In-situ burning would result in ambient concentrations of 

CO, CO2, NOx, PM10, PM2.5, and SO2 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.

Analysis of Accidental Events

Emergency flaring is distinguished from routine flaring by the magnitude, frequency, and 

duration of flaring events. Emergency flaring events are the result of operating conditions that are 

outside normal process and equipment operations. Emergency flaring is generally characterized by 

infrequent occurrence, high-emission rates, and short durations. Potential impacts to air quality are 

not expected to be significant, except in the rare case of a catastrophic event, which is not part of a 

proposed lease sale and not likely expected to occur. Therefore, the potential impacts of a 

reasonably foreseeable accidental gas release analyzed in this Multisale EIS would be localized and 

short term, and would have no impact to coastal areas, including the Bradwell Bay Wilderness Area, 

Breton National Wilderness Area, Chassahowitza National Wilderness Area, Everglades National 

Park, and St. Marks Wilderness Area. The accidental event impacts on air quality over the OCS and 

adjacent onshore areas on accidental gas releases is minor. 

Accidental oil spills, though not considered a routine oil and gas activity, have the potential to 

occur during each phase of oil and gas operations. In April 2010, the Deepwater Horizon explosion 

and oil spill was a catastrophic event that occurred on the Gulf of Mexico OCS. The impacts on air 

quality from Deepwater Horizon explosion and oil spill have been well documented. BOEM does not 

expect accidental events to resemble the Deepwater Horizon explosion and oil spill. BOEM is not 

analyzing the rare, catastrophic Deepwater Horizon explosion and oil spill as an accidental event in 

this chapter but rather is using the information to describe the potential impacts common to spills 

and accidental events regardless of size. To date, air monitoring conducted following the Macondo

loss of well control and spill has not found any pollutants at levels expected to cause long-term harm 

(USEPA, 2010). The loss of well control and blowouts are rare events and of a short duration. 

Potential impacts to air quality are not expected to be significant, except in the rare case of a 

catastrophic event, which is not reasonably expected and not part of a proposed action. Therefore, 

potential impacts as a result of the much smaller reasonably foreseeable accidental spills analyzed 

in this Multisale EIS would be localized and short term, and would have no impact to coastal areas, 

including the Bradwell Bay Wilderness Area, Breton National Wilderness Area, Chassahowitza 

National Wilderness Area, Everglades National Park, and St. Marks Wilderness Area. The 
Description of the Affected Environment and Impact Analysis 4-31

accidental event impact on air quality over the OCS and adjacent onshore areas on oil spills is 

minor. 

Cumulative Impacts

An analysis of the cumulative impacts in the GOM region is described in this section. This 

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 during the 50-year analysis period. This 

cumulative analysis also considers these activities’ effects on the Bradwell Bay Wilderness Area, 

Breton National Wilderness Area, Chassahowitza National Wilderness Area, Everglades National 

Park, and St. Marks Wilderness Area during a 50-year analysis period. These Class I areas are 

protected against excessive increases in air quality-related values—resources sensitive to air 

quality. These air quality-related values include visibility impairment, acid (sulfur and nitrogen) 

deposition, and nitrogen eutrophication. Therefore, one of the tasks of the “Air Quality Modeling in 

the Gulf of Mexico Region” study is to develop a comprehensive emissions inventory of all sources 

in the GOM region and to conduct air quality modeling for cumulative/visibility assessment.

The activities in the cumulative scenario that could potentially impact onshore air quality 

include a regionwide proposed lease sale and the ongoing and future OCS Program, accidental 

releases from oil spills, accidental releases from hydrogen sulfide, and a catastrophic oil spill, as well 

as non-OCS oil- and gas-related activities, State oil and gas programs, and natural events (e.g., 

hurricanes).

OCS Oil- and Gas-Related Impacts

Emissions contributing to air quality degradation come from many sources. Air pollutants on 

the NAAQS list are commonly referred to as criteria pollutants because they are ubiquitous. 

Although these pollutants occur naturally, elevated levels are usually the result of anthropogenic 

activities. The OCS oil- and gas-related activities that could impact air quality include the following: 

platform construction and emplacement; platform operations; drilling activities; flaring; service-vessel 

trips; fugitive emissions; the release of oil, condensate, natural gas, and chemicals used offshore, or 

pollutants from the burning of these products; and a low-probability catastrophic spill, which is not 

part of the proposed action and not likely expected to occur. Emissions of pollutants into the 

atmosphere from the activities associated with the OCS Program are not projected to have 

substantial effects on onshore air quality based on results of past GWEI studies, past ozone studies, 

and modeling results of the 2012-2017 WPA/CPA Multisale EIS.

In the past, BOEM has prepared Gulfwide emissions inventories in 2000, 2005, 2008, and 

2011. In all of the inventories conducted, the largest sources of NOx and VOCs are the OCS nonplatform sources and OCS platform source categories, respectively. Support vessels generate 

about 67 percent of OCS non-platform sources of NOx emissions, whereas within the OCS platform 

source category, cold vents and fugitive emissions comprise more than 83 percent of the total 

VOCs. Previous ozone modeling studies (Yarwood, 2004; Haney, 2008) suggest that the dominant 

cause of onshore ozone exceedances are onshore emission sources but that offshore oil and gas 
4-32 Gulf of Mexico Multisale EIS

activity do cause offshore ozone peaks to occur. Additionally, the Cumulative Increment Analysis for 

the Breton National Wilderness Area study indicated that the cumulative impacts to the Breton 

Wilderness Class I Area are well within the Prevention to Significant Deterioration Class I allowable 

increment (Wheeler et al., 2008).

In the 2012-2017 WPA/CPA Multisale EIS, BOEM used data gathered during the recent 

OCS emission inventories (Year 2008 GWEI), along with a scenario or estimates of future 

production, to evaluate the potential effects of emissions. The affected environment included the 

CPA and WPA; however, BOEM also examined impacts in the EPA. In the CPA, the impacts of the 

OCS oil-and gas related emissions on the onshore air quality were annual NO2 (0.4 μ/m3

) and 

24-hour PM2.5 (0.3 μ/m3

) in the Class I area, which exceed the USEPA’s Significant Impact Levels 

for annual NO2 (0.1 μ/m3

) and 24-hour PM2.5 (0.07 μ/m3) in the Class I area. 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 Class II allowable increments. In the WPA, the 

impacts of the OCS emissions on the onshore air quality were below the USEPA’s Significant Impact 

Levels. Additionally, BOEM examined impacts to air quality in the EPA using the same approach for 

the CPA and WPA. In the EPA, the impacts of the OCS emissions on the onshore air quality were 

below the USEPA’s Significant Impact Levels. The background concentration and impact 

concentration for the CPA, WPA, and EPA were below the NAAQS. The only potential exception is 

for ozone, where there may be some minimal contribution to the ozone at the shoreline.

For this Multisale EIS analysis, BOEM used data gathered during the recent OCS emission 

inventory (Year 2011 GWEI), along with a scenario or estimates of future production, to evaluate the 

potential effects of emissions. The affected environment includes the WPA, CPA, and EPA, which 

comprise the Gulf of Mexico OCS region. The area also includes the federally mandated national 

parks and wilderness areas where visibility is protected more stringently than under the NAAQS. As 

a result of a proposed lease sale, more NAAQS criteria pollutants would be emitted to the affected 

environment. The scenario for this Multisale EIS analysis includes the WPA, CPA, and EPA; the 

Year 2011 GWEI study data were used in this analysis. In the 2012-2017 WPA/CPA Multisale EIS, 

the scenario included the WPA and CPA, but the EPA was analyzed as a supplement to that 

Multisale EIS; the Year 2008 GWEI study data were used in this analysis. Since the Year 2008 and 

Year 2011 GWEI study results are similar and the scenario analyzed includes the WPA, CPA, and 

EPA, BOEM concludes that the impacts of cumulative activities on air quality over the OCS and 

adjacent onshore areas would be moderate; however, the incremental impacts as a result of a 

proposed lease sale would be minor. 

Non-OCS Oil- and Gas-Related Impacts

Onshore emission sources from non-OCS oil- and gas-related activities include power 

generation, industrial processing, manufacturing, refineries, commercial and home heating, and 

motor vehicles (Chapter 3.3.2.6). The total impact from the combined onshore and offshore 

emissions would have an effect on the ozone nonattainment areas in southeast Texas and the 

parishes near Baton Rouge, Louisiana.
Description of the Affected Environment and Impact Analysis 4-33

State oil and gas programs (Chapter 3.3.2.1) onshore, in territorial seas, and in coastal 

waters also generate emissions that affect onshore air quality. These emissions are regulated by 

State agencies and/or the USEPA. Reductions in emissions have been achieved through the use of 

low sulfur fuels, catalytic reduction, and other efforts and, as a result, constitute minor impacts to 

onshore air quality.

Other major factors influencing offshore environments, such as sand borrowing (Chapter 

3.3.2.7.6), commercial transportation (Chapter 3.3.2.3), military vessels, and recreational vessels 

also generate emissions that can affect air quality. These emissions are regulated by State 

agencies and/or the USEPA. Reductions have been achieved through the use of low sulfur fuels 

and catalytic reduction and, as a result, constitute slight impacts to onshore air quality.

Hurricanes (Chapter 3.3.2.10.2) mainly cause damage to offshore infrastructures and 

pipelines, which may result in an oil spill. A hurricane would cause minor effects on the onshore air 

quality since air emissions in the event of a hurricane are temporary sources. For the cumulative 

scenario, the emissions from oil spill and the associated response activities and infrastructure repair 

activities are expected to be the same as a proposed lease sale and to have lesser effects on the 

onshore air quality.

Additionally, recent information shows that intercontinental dust transport may have impacts 

on the GOM’s air quality. For example, dust from Central America and North Africa has been found 

in the Texas atmosphere. 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 (State of Texas, Commission on Environmental Quality, 2014). The transAtlantic transport of North African dust by summertime trade winds occasionally increases ambient 

particulate matter (PM) concentrations in Texas above air quality standards (Bozlaker et al., 2013). 

These results indicate that an increase in visibility impairment in Texas is likely due to transport of 

dust rather than OCS oil- and gas-related emission sources.

The incremental contribution of a proposed lease sale to the cumulative impacts would most 

likely have a slight effect on coastal nonattainment areas. Portions of the Gulf Coast onshore areas 

have ozone levels that exceed the Federal air quality standard, but the incremental contribution from 

a proposed lease sale would be very small. The cumulative contribution to visibility impairment from 

a proposed lease sale is also expected to be very small. The cumulative impacts on air quality over 

the OCS and adjacent onshore areas would be moderate, but the incremental impacts as a result of 

a proposed lease sale would be minor. 
4-34 Gulf of Mexico Multisale EIS

Incomplete or Unavailable Information

This section discusses the incomplete or unavailable information needed to assess the 

impacts from OCS oil and gas-related activities. The air modeling study results that are necessary 

to determine if lease sale emissions adversely impact the State/seaward boundary or the shoreline 

are unavailable. A contract exists to obtain this information and the results should be available in 

future EIS documents.

In order to accurately assess the impacts of a proposed lease sale, BOEM uses data 

gathered from recent Gulf of Mexico OCS emission inventories, along with scenarios or estimates of 

future production. The scenarios provide (1) the assumptions for and estimates of future activities, 

(2) the rationale for the scenario assumptions and estimates, and (3) the type, frequency, and 

quantity of emissions from offshore sources associated with a proposed lease sale.

BOEM determines the projected total emissions that would result from the activities on a 

lease based on estimated emissions from various OCS non-platform and OCS platform equipment 

types, such as diesel engines and generators, and the level of offshore activity projected in Chapter 

3.1. These same emissions estimates are used as inputs for modeling scenarios to predict future 

impacts. The study results are not available in time for this Draft Multisale EIS, but BOEM expects 

that they would be included in future EIS documents. To address data gaps and current impacts, 

BOEM used emissions inventory data, available studies, postlease plan information, and current 

proposed lease sale scenario data, as well as previous proposed action scenario data, to reach our 

impact conclusions.

Air Quality Models

In 2014, BOEM awarded a contract to complete an air quality modeling study in the GOM 

region. The “Air Quality in the Gulf of Mexico Region” study (GM-14-01) will use photochemical and 

dispersion air quality modeling in the GOM region to assess the impacts of OCS oil and gas 

development to nearby States, as required under the OCSLA. The pollutants covered in this study 

are the criteria pollutants (i.e., CO, NOx, PM2, PM10, SO2, Pb, and O3), volatile organic compounds 

(VOCs), hydrogen sulfide (H2S), and ammonia (NH3).

Inputs to the model include the locations of the emission sources and the receptors, the 

aforementioned emissions, source parameters such as source height and source stack gas 

temperature, and a 5-year history of meteorological conditions. The latter two parameters influence 

the dispersion of the pollutant as it is transported from the source to the receptor. The model output 

is the concentration of the pollutant at the onshore receptor location at specified time intervals. The 

proposed lease sales would have reasonably foreseeable adverse effects to air quality, but at the 

time of this Draft Multisale EIS, results from the “Air Quality Modeling in the Gulf of Mexico Region” 

study are not available to evaluate the impacts of a proposed lease sale. However, this impact 

analysis will be updated in future EIS documents to include the results of this model.
Description of the Affected Environment and Impact Analysis 4-35

The results of photochemical and dispersion modeling would be used to predict the impact of 

emissions from both current and proposed OCS oil- and gas-related activities. The accuracy of the 

modeling predictions depends on several factors, including the representative meteorological 

dataset and rate of emissions. Thus, the air quality impact analyses are only as accurate as the 

meteorological dataset applied to disperse and transport the pollutants, and only as comprehensive 

as the emissions inventory on which the analyses are based. While the USEPA, State agencies, 

and Regional Planning Organizations have conducted air quality modeling studies that include the 

GOM region, efforts are needed to bring together data from these resources that would contribute to 

BOEM’s comprehensive understanding of how GOM region OCS oil and gas production activities 

affect the air quality of any state, particularly with regard to annual and short-term NAAQS. The 

results of photochemical and dispersion modeling would be used to estimate pre- and postlease 

impacts of offshore oil and gas.

Air quality modeling requires several input datasets, i.e., meteorology, emissions inventories, 

and ambient pollutant concentrations. Meteorological information is needed for air quality modeling 

because parameters such as wind speed, wind direction, air temperature, and humidity are required 

by models to determine the rate that pollutants disperse and react in the atmosphere. Sources of 

meteorological information include datasets of measurements gathered at various locations within 

the GOM region domain. However, the spatial coverage of measurements is insufficient to describe 

the three-dimensional structure of the atmosphere away from measurement locations. Using 

measurement data as inputs, gridded meteorological models are able to estimate meteorological 

conditions in regions far from measurement sites. The results of these models are often used to 

establish conditions near remote pollutant sources or remote locations downwind of pollutant 

sources. 

In past EIS assessments, BOEM used the Offshore and Coastal Dispersion model version 5 

(OCD 5 model) to assess offshore impacts. One of the limitations of the OCD model is that it is 

unable to directly model contributions to ambient ozone (O3), as ozone is formed in the ambient 

atmosphere through chemical reactions from precursor pollutants and energy from sunlight. To 

address this limitation, BOEM examined available studies on OCS oil- and gas-related activities’ 

contribution to onshore ozone levels. The findings of these prior studies suggest that the dominant 

cause of onshore ozone exceedances are onshore emissions in urban and industrial areas but that 

offshore oil- and gas-related activity do cause offshore ozone peaks to occur. However, these 

studies need to be updated and made more comprehensive to determine the potential impacts of oiland gas-related activities from a proposed lease sale.

Assumptions

The air quality in the GOM can be affected by the pollution emitted from OCS oil- and gasrelated sources as well as non-OCS oil- and gas-related sources. These pollution sources can also 

emit a wide variety of pollutants. To improve air quality and reduce air pollution, the Clean Air Act 

Amendments set regulatory limits on pollutants that help to ensure basic health and environmental 

protection from air pollution. To assess the amount of pollution being emitted, pollutants have to be 
4-36 Gulf of Mexico Multisale EIS

measured. To determine impacts from these pollutants, emission-related conditions (e.g., rate of 

emission, height, and distance of sources from coastline) and environmental conditions (e.g., wind 

speed and direction, humidity, temperature, and height of the atmospheric surface layer where 

pollutants are transported) are calculated.

Emissions from activities related to prior lease sales are represented by the GOAD 2011 

database. Emissions from BOEM’s proposed lease sales are estimated from the exploration and 

development scenario and have been included in the emission inventory that will be used in the 

model to determine routine impacts. The “Air Quality in the Gulf of Mexico Region” modeling study 

includes development of meteorological datasets appropriate for air quality modeling of the study 

area (which includes a proposed lease sale), comprehensive emissions inventory of all sources in 

the GOM region, and air quality modeling for the cumulative impacts and visibility assessment. 

Given that BOEM does not have the results from the ongoing air quality modeling study yet, for this 

Draft Multisale EIS, BOEM has had to rely on emissions inventory data, available studies on OCS 

oil- and gas-related activities, and postlease exploration and development plan information, as well 

as previous proposed action scenario data and impacts analysis to fill data gaps. Since BOEM has 

not had the resources to conduct such a robust analysis in previous Multisale EISs, BOEM used 

past studies, emission inventories, and postlease plan information to assess impacts. This approach 

was adequate because it assessed a combination of pollutants from OCS oil- and gas-related 

activities, non-OCS oil- and gas-related activities, and non-oil and gas activities.

4.1.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative) 

As mentioned in Chapter 3, for a proposed lease sale under Alternative A, BOEM projects 

that no more activity would occur than has resulted in the past from the highest CPA lease sale 

combined with the highest WPA lease sale. Each stage of operation within each phase of a 

proposed lease sale results in a minor air quality impact when considering the countervailing effects 

of actual operations together with dilution and diffusion of the pollutants over time and distance. The 

emission sources would not produce emissions sufficient to overwhelm the effects of wind and 

transport in a single area, causing deterioration of air quality over the regionwide OCS. The 

incremental contribution of a single regionwide proposed lease sale would likely have a minor

impact on coastal areas. Portions of the Gulf Coast onshore areas have ozone levels that exceed 

the Federal air quality standard, but the incremental contribution from a regionwide proposed lease 

sale would be very small.

4.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Since this Alternative excludes the available unleased blocks in the WPA, it would result in 

activity concentrated in the CPA/EPA. As mentioned in Chapter 3, for a proposed lease sale under 

Alternative A, BOEM projects that no more activity would occur than has resulted in the past from 

the highest CPA lease sale combined with the highest WPA lease sale. Therefore, the impacts to 

Alternative B would be very similarly to Alternative A. The incremental contribution of a single 

CPA/EPA proposed lease sale would likely have a minor impact on coastal nonattainment areas. 
Description of the Affected Environment and Impact Analysis 4-37

Water quality is a term used to 

describe the condition or 

environmental health of a 

waterbody or resource, 

reflecting its particular 

biological, chemical, and 

physical characteristics and 

the ability of the waterbody to 

maintain the ecosystems it 

supports and influences. It is 

an important measure for both 

ecological and human health.

Portions of the Gulf Coast onshore areas have ozone levels that exceed the Federal air quality 

standard, but the incremental contribution from a proposed lease sale would be very small.

4.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Since this Alternative excludes the available unleased blocks in the CPA/EPA, it would result 

in activity concentrated in the WPA. As mentioned in Chapter 3, a maximum of 13 percent of the oil 

production and associated activity and 19 percent of the gas production and associated activity 

would occur in the WPA. While the WPA is a smaller area with less projected activity than is 

proposed for the CPA/EPA under Alterative B, the smaller area could decrease impacts to 

communities from production platforms and also increase total emissions due to travel distances for 

marine vessels; the potential impacts would remain minor. The incremental contribution of a single 

WPA proposed lease sale would likely have a minor impact on coastal areas. Portions of the Gulf 

Coast onshore areas have ozone levels that exceed the Federal air quality standard, but the 

incremental contribution from a proposed lease sale would be very small. 

4.1.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D would have the same analysis and potential impacts as Alternative A, B, or C 

because there are so few unleased blocks subject to the Topographic Features, Live Bottom 

(Pinnacle Trend), and Blocks South of Baldwin County, Alabama, Stipulations. The difference 

between Alternatives A, B, and C with and without any combination of these stipulations is 

negligible for air quality. The impacts under Alternative D would not be much different and likely not 

even measurable when compared with the other alternatives.

4.1.2.5 Alternative E—No Action

BOEM has concluded in Chapter 2.3 that the selection of Alternative E would result in no 

additional discernible impacts to the resources analyzed. Cumulative impacts of current and past 

activities, however, would continue to occur under this alternative.

4.2 WATER QUALITY

Coastal water impacts associated with routine activities 

include increases in turbidity resulting from pipeline installation 

and navigational canal maintenance, discharges of bilge and 

ballast water from support vessels, and runoff from shore-based 

facilities. Offshore water impacts associated with routine 

activities result from discharge of drilling muds and cuttings, 

produced water, and residual chemicals used during workovers. 

The discharge of drilling muds and cuttings causes temporary

increased turbidity and changes in sediment composition. The 
4-38 Gulf of Mexico Multisale EIS

discharge of produced water results in increased concentrations of some metals, hydrocarbons, and 

dissolved solids. Structure installation and removal and pipeline placement disturb the sediments 

and cause increased turbidity. In addition, offshore water impacts result from supply and servicevessel bilge and ballast water discharges.

The activity associated with a proposed lease sale could contribute a small percentage of the 

existing and future OCS oil- and gas-related activities. The specific discharges, drill muds, cuttings 

and produced water, and accidents resulting in spills would occur in proportion to production and, 

therefore, would add a small increase to the anticipated impacts. Furthermore, the vessel traffic and 

related discharges associated with a proposed lease sale are a fraction of the ongoing commercial 

shipping and military activity in the Gulf of Mexico. The impact of discharges, sediment 

disturbances, and accidental releases are a small percentage of the overall activity and the overall 

impacts to coastal and offshore waters.

The USEPA (Regions 4 and 6) regulates all waste streams generated from offshore oil- and 

gas-related activities. Section 403 of the Clean Water Act requires that National Pollutant Discharge 

Elimination System (NPDES) permits be issued for discharges to the territorial seas (baseline to 3 mi 

[5 km]), the contiguous zone, and the ocean in compliance with USEPA’s regulations for preventing 

unreasonable degradation of the receiving waters.

The authority for the NPDES program is given at 40 CFR part 125 subpart M, “Ocean 

Discharge Criteria.” The purpose of the NPDES program is to prevent the unreasonable 

degradation of the marine environment as described in 40 CFR § 125.122. In accordance with 

definitions stated at 40 CFR § 125.121, “unreasonable degradation of the marine environment” 

means (1) significant adverse changes in ecosystem diversity, productivity, and stability of the 

biological community within the area of discharge and surrounding biological communities; (2) threat 

to human health through direct exposure to pollutants or through consumption of exposed aquatic 

organisms; or (3) loss of aesthetic, recreational, scientific, or economic values, which is 

unreasonable in relation to the benefit derived from the discharge.

Regulated wastes include drilling fluids, drill cuttings, deck drainage, produced water, 

produced sand, well treatment fluids, well completion fluids, well workover fluids, sanitary wastes, 

domestic wastes, and miscellaneous wastes. The bulk of waste materials produced by offshore oiland gas-related activities are produced water (formation water) and drilling muds and cuttings 

(USEPA, 2009b). There are two general NPDES permits that cover the Gulf of Mexico. Permit 

GMG290000, issued by USEPA Region 6, covers the WPA and CPA, and Permit GEG460000, 

issued by USEPA Region 4, covers the EPA. The USEPA Regions’ jurisdictional areas are shown in 

Figure 3-9 (USEPA, 2009b).

To meet the goal of preventing unreasonable degradation of the marine environment, 

Section B of the NPDES permits specifies effluent limitations and monitoring requirements for 

offshore oil and gas facilities. Discharged regulated wastes may not contain free oil or cause an oil 

sheen on the water surface, and the oil/grease concentration may not exceed 42 milligrams per liter 
Description of the Affected Environment and Impact Analysis 4-39

(mg/L) daily maximum or 29 mg/L monthly average. Discharge of drilling fluids containing oil 

additive or formation oil is prohibited, except that which adheres to cuttings and certain small volume 

discharges. Barite used in drilling fluids may not contain mercury or cadmium at levels exceeding 

certain concentrations (1.0 mg/kg mercury and 3.0 mg/kg cadmium). Some discharged regulated 

wastes (e.g., produced waters and miscellaneous wastewaters) must also be characterized using a 

whole effluent toxicity test, where a population of mysid shrimp or inland silverside minnows are 

exposed to a certain concentration of the waste stream, and mortality of the population must not 

exceed 50 percent. The NPDES permits allow a mixing zone for some regulated discharges as 

defined at 40 CFR § 125.121 to meet compliance using an approved plume model. The NPDES 

permits require no discharge within 1,000 m (3,281 ft) of an area of biological concern. Region 4 

also requires no discharge within 1,000 m (3,281 ft) of any federally designated dredged material 

ocean disposal site.

Impacts on water quality from operational discharges related to a proposed lease sale are 

expected to be minimal because of the following: (1) USEPA regulations to prevent unreasonable 

degradation of the marine environment; (2) prohibitions on discharge of some waste types; 

(3) prohibitions on discharge near sensitive biological communities; (4) monitoring requirements and 

toxicity testing; (5) mixing zone and dilution factors; (6) operational discharges are temporary in 

nature; and (7) any effects from elevated turbidity would be short term, localized, and reversible. As 

such, assuming compliance with applicable regulations, the impacts from the discharge of regulated 

wastes from routine operations would require no additional mitigation.

These OCS oil- and gas-related sources are related to the activities listed in Table 4-3

below. This table also illustrates the impact level conclusions for each impact-producing factor 

reached in this chapter’s impact analysis.

Table 4-3. Water Quality Impact-Producing Factors.

Water Quality Magnitude of Potential Impact

ImpactProducing 

Factors

Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Geological 

Sampling Negligible Negligible Negligible Negligible None

Bottom Area 

Disturbance Negligible Negligible Negligible Negligible None

Operational 

Discharges and 

Wastes

Negligible Negligible Negligible Negligible

None

Pipeline 

Installation Negligible Negligible Negligible Negligible None

Decommissionin

g and Removal 

Operations

Negligible Negligible Negligible Negligible

None
4-40 Gulf of Mexico Multisale EIS

Water Quality Magnitude of Potential Impact

ImpactProducing 

Factors

Alternative A Alternative B Alternative C Alternative D Alternative E

Accidental Impacts

Drilling Fluid 

Spills Minor Minor Minor Minor None

Chemical and 

Waste Spills Minor Minor Minor Minor None

Oil Spills

 Without 

 Mitigation Moderate Moderate Moderate Moderate None

 With Mitigation Minor Minor Minor Minor None

Cumulative Impacts

OCS Oil and Gas Negligible Negligible Negligible Negligible Negligible

Non-OCS Oil and 

Gas Negligible Negligible Negligible Negligible Negligible

Impact-Level Definitions

For the purpose of the following discussion, the significance of impact-producing factors on 

water quality is discussed below. The criteria for significance reflect consideration of the context and 

intensity of impact (40 CFR § 1508.27), based on four parameters: detectability (i.e., measurable or 

detectable impact); duration (i.e., short term, long term); spatial extent (i.e., localized, extensive); 

and severity (i.e., severe, less than severe). For water quality, the significance criteria have been 

broadly defined as follows:

• Negligible – Impacts are defined as short-term (less than 1 year), localized 

contaminants and turbidity that present little to no detectable impact.

• Minor – Impacts are defined as detectable, short-term, localized, or extensive 

but less than severe; however, detectable contaminant concentrations may 

exceed regulatory levels. Minor impacts may have little to no effect on marine 

life.

• Moderate – Impacts are defined as detectable, short term, extensive, and 

severe; or impacts are detectable, short term or long term, localized and severe; 

or impacts are detectable, long term, extensive, or localized but less than severe. 

Moderate impacts may result in acute or chronic effects to marine life.

• Major – Impacts are defined as detectable, short term or long term, extensive, 

and severe; however, major impacts may result in acute or chronic effects to 

marine life and may potentially cause human health effects.
Description of the Affected Environment and Impact Analysis 4-41

4.2.1 Description of the Affected Environment

For the purposes of this analysis, the GOM is divided into coastal and offshore waters. 

Coastal waters are defined to include all bays and estuaries from the Rio Grande River to the Florida 

Bay. Offshore waters are defined to include those waters extending from outside the barrier islands 

to the Exclusive Economic Zone, located within State waters and the Federal OCS. The inland 

extent is defined by the Coastal Zone Management Act. Offshore waters are divided into three 

regions: the continental shelf west of the Mississippi River; the continental shelf east of the 

Mississippi River; and deep water (>1,000 ft; 305 m).

The U.S. portion of the GOM follows the coastline of five states, from the southern tip of 

Texas moving eastward through Louisiana, Mississippi, Alabama, and ending in the Florida Keys. 

Including the shorelines of all barrier islands, wetlands, inland bays, and inland bodies of water, the 

combined coastlines of these states total over 75,639 km (47,000 mi) (USDOC, NOAA, 2008a). The 

GOM coastal areas comprise over 750 bays, estuaries, and sub-estuary systems that are associated 

with larger estuaries (USEPA, 2012b). More than 60 percent of U.S. drainage, including outlets from 

33 major river systems and 207 estuaries, flows into the GOM (USEPA, 2014c) and has a large 

influence on water quality. The largest contributing inputs from the U.S coast are from the 

Mississippi and Atchafalaya Rivers in Louisiana. Additional freshwater inputs into the GOM originate 

in Mexico, the Yucatán Peninsula, and Cuba.

The physical oceanography of the deep Gulf can be approximated as a two-layer system 

with an upper layer about 800- to 1,000-m (2,625- to 3,281-ft) deep that is dominated by the Loop 

Current and associated clockwise (anticyclonic) eddies (Welsh et al., 2009; Inoue et al., 2008); and 

the lower layer below ~1,000 m (3,281 ft) that has near uniform currents (Welsh et al., 2009; Inoue 

et al., 2008). Deep waters east of the Mississippi River are affected by the Loop Current and 

associated warm-core anticyclonic eddies, which consist of clear, low-nutrient water (Muller-Karger 

et al., 2001). Cold-core cyclonic eddies also form at the edge of the Loop Current and are 

associated with upwelling and nutrient-rich, high-productivity waters. More details on the physical 

oceanography of the Gulf of Mexico are available in Chapter 3.3.2.9.1. 

The primary factors influencing coastal and offshore environments are temperature, salinity, 

dissolved oxygen, chlorophyll content, nutrients, potential of hydrogen (pH), oxidation reduction 

potential (Eh), pathogens, transparency (i.e., water clarity, turbidity, or suspended matter), and 

contaminant concentrations (e.g., heavy metals, hydrocarbons, and other organic compounds).

Surface water temperatures in the Gulf of Mexico vary seasonally from about 29 oC (84 oF) in 

the summer to about 19 oC (65 oF) in the winter (Gore, 1992). In the summer, warm water may be 

found from the surface down to a thermocline at depths to about 160 ft (50 m). Minimum water 

temperatures below the 5,000-ft (1,524-m) water depth approach 4o C (39 oF) (Forrest et al., 2007).

The salinity at the sea surface in the offshore Gulf of Mexico is generally 36 parts per 

thousand (ppt) (Gore, 1992). Lower salinities are characteristic nearshore where fresh water from 
4-42 Gulf of Mexico Multisale EIS

the rivers mixes with shallow Gulf waters. For example, salinity in open water near the coast may 

vary between 29 and 32 ppt during fall and winter, but it may decline to 20 ppt during spring and 

summer due to increased runoff (USDOI, MMS, 2000b).

There is a surface turbidity layer associated with the freshwater plumes from the Mississippi 

and Atchafalaya Rivers due to suspended sediment in river discharge, especially during seasonal 

periods of heavy precipitation. High turbidity may extend up to 50 mi (80 km) offshore the 

Mississippi River and lesser distances to the east and west along the coast. Outside of these areas, 

water clarity in the Gulf of Mexico improves, with low levels of suspended sediment.

During summer months, shelf stratification results in a large hypoxic zone on the LouisianaTexas shelf in bottom waters (Turner et al., 2005). Hypoxia, the condition of having low dissolved 

oxygen concentration in the water (below 2 mg/L), is caused by excessive nutrients and other 

oxygen-demanding contaminants (refer to Chapter 3.3.2.12). Hypoxia often forms when the water 

column becomes vertically stratified and mixing between oxygenated surface waters and bottom 

waters cannot occur. Hypoxia is a widespread phenomenon on the continental shelf of the northern 

GOM and is the largest hypoxic zone in the western Atlantic Ocean (Rabalais and Turner, 2001). 

The hypoxic zone in the GOM occurs seasonally and is influenced by the timing of the Mississippi 

and Atchafalaya River discharge. Formation of the zone is attributed to nutrient influxes and shelf 

stratification, and the zone persists until wind-driven circulation mixes the water column. Recent 

estimates of the area of low oxygen by NOAA (USDOC, NOAA, 2015h) as of August 3, 2015, 

measured 6,474 mi2 (16,760 km2

) (Figure 3-15), an increase from the size measured in 2014 

(5,052 mi2

; 13,085 km2) and larger than the estimated size (5,838 mi2; 15,120 km2) forecast by 

LUMCON (2015) in June 2015. The size of the hypoxic zone has been shown to be directly 

correlated with the flux of nitrogen from the Mississippi River (Turner et al., 2012).

Anthropogenic factors that affect coastal water quality include urban runoff and eroded soil 

carrying oil and trace metals, agricultural runoff carrying fertilizer (e.g., nutrients including nitrogen 

and phosphorus), pesticides, fungicides, and herbicides; upstream withdrawals of water for 

agricultural, industrial, and domestic purposes; contamination by industrial and sewage discharges, 

dumping, atmospheric fallout, and spills of oil, chemicals, and hazardous materials (refer to Chapter 

3.3.2.3). Mixing or circulation of coastal water can either improve water quality through flushing or 

be the source of factors contributing to its decline.

Oil/grease and other contaminants associated with the suspended load may ultimately reside 

in the sediments rather than in the water column. For example, a contaminant may react with the 

mineral particles in the sediment and be removed from the water column (e.g., sorption). Thus, 

under appropriate conditions, sediments can serve as sinks for contaminants such as metals, 

nutrients, or organic compounds. However, if sediments are (re)suspended (e.g., due to dredging, a 

storm event, or in conjunction with seasonal mixing and circulation patterns), the resuspension can 

lead to a temporary redox flux, including a localized and temporal release of any formerly sorbed 

metals or nutrients (Caetano et al., 2003; Fanning et al., 1982).
Description of the Affected Environment and Impact Analysis 4-43

Offshore waters, especially deeper waters, are more directly affected by natural seeps (refer 

to Chapter 3.3.2.9.2). Hydrocarbons enter the Gulf of Mexico through natural seeps at a rate of 

approximately 980,392 bbl per year (a range of approximately 560,224-1,400,560 bbl per year) 

(NRC, 2003). Pelagic tar is a common form of hydrocarbon contamination present in the offshore 

environment of the GOM (U.S. Dept. of Homeland Security, CG, 2015b). Higher tar concentrations 

were closely correlated with proximity to the Loop Current. Van Vleet et al. (1983) estimated that 

that approximately 7,000 tons (7,112,323 kg) of pelagic tar are discharged annually from the GOM 

into the North Atlantic Ocean and that roughly half of the oil may be brought into the Gulf from the 

Caribbean Sea via the Loop Current, while the remainder appears to originate in the GOM.

The USEPA’s National Coastal Condition Report IV categorizes coastal waters of the United 

States based on an evaluation of five indices including water and sediment quality. The water 

quality index for the GOM’s coastal waters was rated fair, and the sediment quality index was rated 

poor (USEPA, 2012b). Sediment quality poses an impact risk to coastal water quality as 

contaminants in sediments may be resuspended into the water by anthropogenic activities, storms, 

or other natural events. Sediments in the GOM coastal region have been found to contain 

pesticides, metals, polychlorinated biphenyls (PCBs), and occasionally polycyclic aromatic 

hydrocarbons (PAHs) (USEPA, 2012b). These contaminants are not likely OCS industry-related but 

are more likely from onshore industries and upland practices.

4.2.2 Environmental Consequences

Routine Activities

Impact-producing factors from routine activities identified in Chapter 3.1 include geological 

sampling, bottom area disturbance, operational discharges and wastes, pipeline installation, and 

decommissioning and removal operations. Geological sampling is performed for geological and 

geotechnical evaluation, using grab samples, box cores, and gravity, rotary, and piston core 

methods. Each of these sample techniques disturbs a small area of the seafloor (typically less than 

1 ac [0.4 ha]), creating turbidity. Bottom area disturbances create turbidity and occur during 

emplacement and removal of jack-up drill rigs, anchored semisubmersible drill rigs and drillships, 

platforms, pipelines, and subsea production systems. The emplacement or removal of these 

structures disturbs areas of the seafloor beneath or adjacent to the structure. Anchored catenary 

systems may disturb an area of seafloor up to about 5-7 ac (2-3 ha). Trenching for emplacement of 

pipelines disturbs an area of seafloor up to 2.5 ac (1.0 ha) per kilometer of pipeline (Cranswick, 

2001). These bottom-disturbing activities impact water quality when sediments are resuspended, 

creating turbidity and resulting in a temporary redox flux, including a localized and temporal release 

of components such as metals or nutrients that were associated with the sediment, as described in 

Chapter 4.2.1. Because these areas of disturbance are localized and short term, impacts from

turbidity due to bottom-disturbing activities are considered negligible. 

Operational wastes and discharges are discussed in detail in Chapter 3.1.5.1. These 

wastes include drilling fluids (also known as muds) and cuttings, which are discussed in detail in 

Chapter 3.1.5.1.1. Water-based muds and cuttings are discharged at the seafloor during drilling of 
4-44 Gulf of Mexico Multisale EIS

the shallow portion of the well, prior to installation of surface riser. The resulting splay (pattern of 

mud distribution) on the seafloor may be up to 2,000 ft (610 m) in radius (British Petroleum, 2015), 

indicating that turbidity resulting from riserless drilling settles out relatively quickly. After the riser is 

installed, drilling muds and cuttings are generally discharged from the drilling unit at or near the 

water surface. The heavier mud and cuttings fall close to the drilling unit; however, the resulting 

turbidity plume may extend more than a mile from the drilling unit, depending on currents. Similar to 

bottom-disturbing activities, turbidity generated from drilling muds and cuttings is temporary and 

would settle out quickly. Unlike bottom-disturbing activities, turbidity from drilling muds and cuttings 

is less likely to result in a redox flux.

The discharge of water-based drilling muds and cuttings is allowed under the USEPA Region 

4 and Region 6 NPDES general permits (except in biologically sensitive areas). Under the guidance 

of the NPDES permit, drilling muds can be discharged into the ocean only if they meet USEPA 

requirements, which include testing for toxicity prior to discharge. If they fail the toxicity tests, the 

materials cannot be discharged to the ocean. Therefore, the impact from drilling muds and cuttings 

is considered negligible. 

Other than turbidity, the potential toxic effects of drilling muds are discussed in Chapter 

3.1.5.1.1. Drilling muds may contain synthetic-based fluid (SBF), which is nonpetroleum 

manufactured hydrocarbons incorporated into the barite mud matrix. The SBF is well-characterized, 

has low toxicity and bioaccumulation potentials, and is biodegradable. Also, SBF is not soluble in 

water and is therefore not expected to adversely affect water quality. A previous study of an SBF 

spill (USDOI, MMS, 2004a) concluded that the released SBF dispersed into the water, settled to the 

seafloor, and biodegraded. The SBF would cause a temporary decrease in dissolved oxygen at the 

sediment/water interface. The discharge of SBF-wetted cuttings is allowed under the USEPA 

Region 4 and Region 6 NPDES general permits. Discharge of muds containing SBF is prohibited. 

However, synthetic-based mud (SBM)-wetted cuttings may be discharged after the majority of the 

SBM has been removed (up to 9.4% of SBM may be retained on cuttings for ocean discharge). 

Under the guidance of the NPDES permit, drilling muds can be discharged into the ocean only if they 

meet USEPA requirements, which include testing for toxicity prior to discharge. If they fail the 

toxicity test, the materials cannot be discharged into the ocean. The discharge of drilling muds that 

meet the required regulatory criteria but include very low quantities of SBMs appear to have minimal 

and brief impacts to the ocean environment. As such, the impact from discharging SBF-wetted drill 

cuttings is considered negligible. 

Produced water is discussed in Chapters 3.1.5.1.2. This waste stream may include well 

treatment chemicals, dissolved solids from the geological formation, inorganic and organic 

chemicals, and radionuclides. The discharge of produced water is allowed under the USEPA 

Region 4 and Region 6 NPDES general permits with requirements for the treatment method and 

prior analytical and toxicity testing. When discharge into the ocean is permitted, the discharge 

cannot exceed set discharge rates. As with drilling muds, following treatment, produced water must 

be tested for toxicity according to USEPA requirements. If it fails the toxicity test, it cannot be 

discharged into the ocean. Therefore, the potential impact from discharge of produced water is 
Description of the Affected Environment and Impact Analysis 4-45

considered negligible. Furthermore, the produced-water discharge loadings estimated for the entire 

hypoxic zone are several orders of magnitude smaller than those entering the Gulf of Mexico from 

rivers. The total nitrogen loading is about 0.16 percent and the total phosphorus loading is about 

0.013 percent of the nutrient loading coming from the Mississippi and Atchafalaya Rivers (Argonne 

National Laboratory et al., 2005). As such, the incremental effect of produced water contributing to 

the effects of the hypoxic zone is considered negligible. 

Other operational waste streams identified in Chapter 3.1.5 include well treatment, 

workover, and completion fluids; bilge, ballast, and fire water; cooling water; deck drainage; and 

treated domestic and sanitary wastes. These waste streams are also discharged in accordance with 

the USEPA Region 4 and Region 6 NPDES general permits with requirements for the treatment 

method and prior analytical testing. Wastes that do not meet regulatory requirements for offshore 

discharge into the ocean must be properly disposed of or recycled onshore according to State and 

Federal regulations. Assuming compliance with these requirements and since the discharge of 

these waste streams is regulated under the general NPDES permit, the impact of the discharge on 

water quality is considered negligible. 

Discharges from supply/service vessels that support oil and gas operations are discussed in 

Chapter 3.1.5.2. These discharges typically include ballast water, trash and debris, and sanitary 

and domestic wastes, and they are regulated under the NPDES Vessel General Permit (VGP), Small 

Vessel General Permit (sVGP), and MARPOL 73/78. All discharges of ballast water must comply 

with applicable U.S. Coast Guard regulations (33 CFR part 151). The NPDES permit defines 

mandatory ballast water practices required of all vessels. All discharges of oil, including oily 

mixtures, must not contain oil in quantities that may violate applicable water quality standards

pursuant to 40 CFR part 110. Assuming compliance with these regulations, the impact of these 

discharges is considered negligible. 

Discharges related to the onshore disposal of OCS oil- and gas-related wastes (Chapter 

3.1.5.3) are limited to potential point-source runoff from the disposal facilities, which is regulated by 

the facility NPDES permit. Facility NPDES permits set discharge limits for each characterized waste 

stream to protect water quality standards of the receiving waters and require routine discharge 

monitoring to ensure compliance. As such, the impact of regulated point-source runoff on water 

quality is considered negligible. 

Potential impacts to water quality related to decommissioning and removal operations are 

discussed in Chapter 3.1.6. Decommissioning activities may use both explosive and nonexplosive 

technologies to remove structures to a depth of at least 15 ft (5 m) below the mudline. Prior to 

decommissioning, all tanks formerly containing oil or hazardous materials are removed, such that 

the decommissioning may only result in turbidity from the associated bottom-disturbing activity and 

temporary redox flux that could cause a release of formerly-sorbed components. As stated in 

Chapter 3.1.6, it is anticipated that the majority of decommissioning activities would take place 

landward of the 800-m (2,625-ft) isobath, where naturally occurring turbidity and impacted sediments 
4-46 Gulf of Mexico Multisale EIS

are more likely to exist. Because these areas of decommissioning are localized and short term, 

impacts from turbidity due to the associated bottom-disturbing activities are considered negligible. 

In summary, as OCS oil- and gas-related routine events are highly regulated, such that 

effects on water quality are short term, localized, and reversible, and therefore, they would be 

expected to have a negligible impact.

Accidental Events

Impact-producing factors related to OCS oil- and gas-related accidental events are 

discussed in Chapter 3.2. These events primarily involve drilling fluid spills, chemical and waste 

spills, and oil spills.

Water-based fluid (WBF) and SBF spills may result in elevated turbidity, which would be 

short term, localized, and reversible. The WBF is normally discharged to the seafloor during 

riserless drilling, which is allowable due to its low toxicity. For the same reasons, a spill of WBF 

would have negligible impacts. The SBF has low toxicity, and the discharge of SBF is allowed to 

the extent that it adheres onto drill cuttings. A spill of SBF may cause a temporary increase in 

biological oxygen demand and locally result in lowered dissolved oxygen in the water column. Also, 

a spill of SBF may release an oil sheen if formation oil is present in the fluid. Therefore, impacts 

from a release of SBF are considered to be minor. Spills of SBF typically do not require mitigation 

because SBF sinks in water and naturally biodegrades, seafloor cleanup is technically difficult, and 

SBF has low toxicity.

Accidental chemical spills could result in temporary localized impacts on water quality, 

primarily due to changing pH. Chemicals spills are generally small volume compared with spills of 

oil and drilling fluids. As stated in Chapter 3.2.6, during the period of 2007 to 2014, small chemical 

spills occurred at an average annual volume of 28 bbl, while large chemical spills occurred at an 

average annual volume of 758 bbl. These chemical spills normally dissolve in water and dissipate 

quickly through dilution with no observable effects. Also, many of these chemicals are approved to 

be commingled in produced water for discharge to the ocean, which is a permitted activity. 

Therefore, impacts from chemical spills are considered to be minor and do not typically require 

mitigation because of technical feasibility and low toxicity after dilution.

Oil spills have the greatest potential of all OCS oil- and gas-related activities to affect water 

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

offshore waters because the oil dissipates quickly through dispersion and weathering while still at 

sea. Reasonably foreseeable larger spills (≥1,000 bbl), however, could impact water quality in 

coastal and offshore waters. Oil spills, regardless of size, may allow hydrocarbons to partition into 

the water column in a dissolved, emulsion, and/or particulate phase. Therefore, impacts from 

reasonably foreseeable oil spills are considered moderate. Mitigation efforts for oil spills may 

include booming, burning, and the use of dispersants (Chapter 3.2.7.2). These methods may cause 

secondary impacts to water quality, such as the introduction of additional hydrocarbon into the 
Description of the Affected Environment and Impact Analysis 4-47

dissolved phase through the use of dispersants and the sinking of hydrocarbon residuals from 

burning. As such, impacts to water quality after mitigation efforts are considered to be minor. 

Cumulative Impacts

OCS Oil- and Gas-Related Impacts

Routine OCS oil- and gas-related impacts are considered to be a small contribution to 

cumulative impacts because they are considered to be negligible (refer to Chapter 3.3.1). 

Accidental OCS Program spills of drilling fluids, chemicals, and oil are considered to have moderate

impacts prior to mitigation (with minor impacts where certain mitigations are implemented). 

However, other contaminant sources unrelated to the OCS Oil and Gas Program contribute 

significant impacts to water quality in the GOM, as discussed below.

Non-OCS Oil- and Gas-Related Impacts

Impact-producing factors related to non-OCS oil- and gas-related anthropogenic events and 

natural processes discussed below are described in Chapter 3.3.2. These cumulative effects are 

important for comparison with OCS oil- and gas-related effects relative to their potential impacts on 

water quality.

Non-OCS oil-and gas-related anthropogenic impacts that are regulated include non-OCS oiland gas-related activities in State waters, marine vessel activity, LNG ports and terminals, landbased point-source discharges, aquaculture, OCS sand borrowing, maintenance dredging and 

dredged material disposal. Discharges as a result of these activities require NDPES permits. 

Discharges in compliance with regulations, including the NPDES permit and other provisions of the 

Clean Water Act, are considered negligible because the regulations are risk-based to assure little to 

no effect on marine life, and monitoring is required to demonstrate compliance. Therefore, the 

impacts on water quality from these activities are considered negligible. 

Unregulated anthropogenic activities often have associated impacts on water quality of 

greater magnitude than regulated activities. Non-OCS oil- and gas-related oil spills present the 

same impacts as described above. Land-based nonpoint-source discharges from uncontained 

runoff and groundwater discharge are a source of suspended solids, organic matter, nutrients, and 

other pollutants in river outflow. Nutrients in river outflow cause eutrophication and hypoxia, which 

can cause unreasonable degradation of the marine environment. Therefore, impacts to water quality 

from hypoxia are considered major. Pollutants in nonpoint-source discharges are incorporated into 

bottom sediments within the coastal zone and have the potential to cause impacts to water quality. 

Therefore, impacts to sediments from nonpoint-source discharges are considered moderate. 

Because marine trash and debris in the water column has the potential to cause health effects in 

marine life due to entanglement or ingestion, the impacts to water quality are considered moderate. 

Discharges associated with military activities (Chapter 3.3.2.3.2) were evaluated for their 

potential impacts to water quality. The floating portion of debris that may be released into the GOM 
4-48 Gulf of Mexico Multisale EIS

as a result of military activities presents the same risks to water quality as marine trash and debris, 

and the associated impacts are considered moderate. The sinking portion of military debris is 

largely inert, and the associated impacts to water and sediment quality are considered minor. 

In-flight jettisoning of fuel is short term and likely volatilizes into the atmosphere quickly after release. 

Therefore, the associated impact of released fuel to water quality is considered minor. 

Potentially polluting shipwrecks (e.g., bulk cargo and fuel leakage from the wreck), chemical 

weapon disposal areas, and industrial waste disposal areas, which may cause potential impacts to 

water quality, are discussed in Chapter 3.3.2.4. The potential impacts to water quality from 

shipwrecks are dependent on the type of fuel and cargo present on the wreck and the flow rate of 

contaminants into the water column. Light oils released from wrecks are localized and generally 

degrade in the short term, and may present only minor impacts to water quality. Chemical weapons 

were known to contain extremely toxic substances that, if leaked into the water column, could impact 

water quality over the long term. Some of the known disposal areas are in shallow waters, and there 

have been occurrences where trawlers have inadvertently raised 55-gallon drums suspected of 

containing chemical weapons. Since potential exposures of humans to these substances may occur 

via the water column, the impacts to water quality are considered moderate. Wastes disposed of in 

historical industrial waste dumpsites areas were known to contain toxic substances that, if leaked, 

could impact water quality over the long term. As such, the impacts to water quality are considered 

moderate. 

Natural events also contribute to cumulative impacts on water quality resulting from oil seeps 

and turbidity caused by suspended sediment load from rivers and erosion from currents, storms, and 

downslope sediment transport. Hurricanes may increase the potential for spills and cause shortterm turbidity. Oil seeps (Chapter 3.3.2.9.2) present the same potential impacts as an accidental oil 

spill, except that the seeps may persist over the long term. As such, the impacts to water quality are 

considered moderate. Natural turbidity persists in coastal waters due to river outflow and may be 

intermittent in response to currents, storms, and downslope sediment transport. The effects from the 

elevated turbidity on water quality would be short term, localized, and reversible, and are considered 

minor. 

The impacts of routine operational discharges from the OCS oil and gas program on water 

quality are short term and localized, and are considered negligible. The potential impacts from 

reasonably foreseeable oil spills as a result of the proposed action on water quality after mitigation 

are also short term and are considered minor. The impacts from a proposed lease are a small 

addition to the cumulative impacts on water quality when compared with inputs from hypoxia, 

potentially leaking shipwrecks, chemical weapon and industrial waste dumpsites, natural oil seeps, 

and natural turbidity. The incremental contribution of the routine activities and accidental discharges 

associated with a proposed lease sale to the cumulative impacts on water quality would be 

negligible. 
Description of the Affected Environment and Impact Analysis 4-49

Incomplete or Unavailable Information

In preparation for this Multisale EIS, BOEM has reviewed the latest information available 

relative to potential impacts on water quality, which is presented in Chapter 3.1. BOEM has 

identified incomplete or unavailable information that may be relevant to reasonably foreseeable 

impacts on 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 foreseen that all related information 

would be publicly available to include in this NEPA analysis regardless of the costs or resources 

needed. BOEM has used the best available scientific information to date and believes that any 

additional information would not likely change the ranking of impacts and is not essential to a 

reasoned choice among alternatives.

4.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Under Alternative A, BOEM estimates that a total of 53-984 exploration and delineation wells 

and 61-767 development and production wells would be drilled and that 221-1,332 mi 

(355-2,144 km) of pipeline would be installed over a 50-year period. The projected number of wells 

and miles of pipeline are used as an indicator of total activity, which correlates to the volume of 

routine operational waste discharged, amount of bottom disturbance and drill cuttings causing 

turbidity, and the potential for drilling fluid and chemical and oil spills. Some localized and short-term 

moderate impacts could occur for site-specific actions; however, these activities would be reviewed 

on a case-by-case basis and applicable commonly applied mitigating measures (refer to 

Appendix B) would be identified during postlease reviews of plans and permits. Based on the 

previously discussed impact-producing factors for routine activities and accidental events, their 

estimated level of activity, commonly applied mitigating measures, and occurring across the entire 

proposed lease sale area, Alternative A is expected to have minor impacts overall.

4.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B. BOEM estimates that a total of 33-893 exploration and delineation wells 

and 46-671 development and production wells would be drilled and that 158-1,-020 mi 

(254-1,641 km) of pipeline would be installed over a 50-year period. The projected number of wells 

and miles of pipeline are used as an indicator of total activity, which correlates to the volume of 

routine operational waste discharged, amount of bottom disturbance and drill cuttings causing 

turbidity, and the potential for drilling fluid and chemical and oil spills. Based on the previously 

discussed impact-producing factors for routine activities and accidental events, their estimated level 

of activity, commonly applied mitigating measures, and occurring mostly in the CPA/EPA portion of 

the proposed lease sale area, Alternative B is expected to result in minor impacts to water quality. 

As under Alternative A, some localized and short-term moderate impacts could occur for site-specific 

actions; however, these activities would be reviewed on a case-by-case basis and applicable 

commonly applied mitigating measures (refer to Appendix B) would be identified during postlease 

reviews of plans and permits. The environmental consequences of a proposed lease sale under 
4-50 Gulf of Mexico Multisale EIS

Alternative B and the inherent resulting activities to water quality would be slightly smaller than under 

Alternative A and would be more restricted to the CPA/EPA portion of the proposed lease sale area.

4.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Under Alternative C, BOEM estimates that a total of 17-91 exploration and delineation wells 

and 22-96 development and production wells would be drilled and that 65-314 mi (105-505 km) of 

pipeline would be installed over a 50-year period. The projected number of wells and miles of

pipeline are used as an indicator of total activity, which correlates to the volume of routine 

operational waste discharged, amount of bottom disturbance and drill cuttings causing turbidity, and 

the potential for drilling fluid and chemical and oil spills. While all of the leases issued under this 

alternative would occur in the WPA portion of the proposed lease sale area, activities such as vessel 

support and pipeline or coastal infrastructure could occur in the CPA portion of the proposed lease 

sale area. As under Alternatives A and B, postlease activities would be reviewed on a case-by-case 

basis and applicable commonly applied mitigating measures (refer to Appendix B) would be 

identified during site–specific or postlease reviews of plans and permits. Based on the estimated 

level of activity and much smaller geographic area, Alternative C is expected to result in minor

impacts, though fewer impacts than Alternative A or B.

4.2.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

The number of available unleased blocks subject to the Topographic Features, Live Bottom 

(Pinnacle Trend), and Blocks South of Baldwin County, Alabama, Stipulations is small compared 

with the number of unleased blocks being offered under Alternatives A, B, or C. Therefore, the 

activity level (and water quality impacts) that can be expected for Alternative D is similar to 

Alternative A, B, or C, as applicable, which would be minor under all action alternatives.

4.2.2.5 Alternative E—No Action

Under Alternative E, there would be no new activities related to a proposed action (no wells 

drilled and no pipelines installed). Therefore, there would be no associated impacts to water quality 

resulting from a proposed lease sale and, therefore, those additional impacts would be avoided. 

However, cumulative impacts related to past, present, and reasonably foreseeable future activities 

would continue.

4.3 COASTAL HABITATS

4.3.1 Estuarine Systems (Wetlands and Seagrass/Submerged Vegetation)

The estuarine system is the transition zone between freshwater and marine environments. It 

can consist of many habitats, including wetlands and submerged vegetation. While some seagrass 

species can be found farther offshore, the majority is within the coastal area of the GOM and will be 
Description of the Affected Environment and Impact Analysis 4-51

covered in this chapter. The approach of the analysis is to focus on the potential impact-producing 

factors from routine OCS oil- and gas-related activities (i.e., exploration, development, and 

production), as well as accidental events and cumulative impacts (Table 4-4).

Table 4-4. Estuarine Systems Impact-Producing Factors.

Impact-Producing 

Factors

Magnitude of Potential Impact

Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Pipeline 

Construction and 

Maintenance

Negligible Negligible Negligible Negligible None

Navigation Channel 

Maintenance 

Dredging

Negligible Negligible Negligible Negligible None

Vessel Operation 

(support use of 

navigation 

channels)

Negligible Negligible Negligible Negligible None

Disposal of OCS 

Oil- and GasRelated Wastes

Negligible Negligible Negligible Negligible None

Construction and 

Use of Coastal 

Support 

Infrastructure

Negligible Negligible Negligible Negligible None

Accidental Impacts

Oil Spills Minor Minor Minor Minor None

Cumulative Impacts

OCS Oil and Gas Moderate Moderate Moderate Moderate Moderate

Non-OCS Oil and 

Gas Major Major Major Major Major

In this chapter, BOEM reviewed and analyzed routine OCS oil- and gas-related activities and 

reasonably foreseeable accidental events. Routine activities associated with a proposed lease sale 

that takes place on the OCS, where wells are drilled and platforms and pipelines are installed, would 

not impact the wetlands or submerged vegetation that is located miles away. Other routine activities 

that support offshore oil and gas exploration, such as increased vessel traffic (Chapter 3.1.4.4), 

maintenance dredging of navigation canals (Chapter 3.1.4.6), pipeline installation (Chapter 3.1.3.3), 

disposal of OCS oil- and gas-related wastes (Chapter 3.1.5), and construction and maintenance of 

support infrastructure in the coastal areas (Chapter 3.1.7), could potentially impact wetlands. Of 

these impact-producing factors, vessel traffic was not analyzed with respect to seagrass and 

submerged vegetation because OCS vessels (due to their size and use of commercial ports) are 

generally not in areas shallow enough to have large submerged vegetation beds. An analysis of the 

potential impacts from accidental events, primarily oil spills, associated with a proposed lease sale is 

presented in this chapter, as is the incremental contribution of a proposed action to the cumulative 

impacts to wetlands and submerged vegetation. Cumulative impacts were analyzed for OCS oil- 
4-52 Gulf of Mexico Multisale EIS

and gas-related activities and for other sources that could affect wetlands and submerged vegetation 

communities (i.e., human impacts, storms, and vessel traffic). Additional factors that could affect 

estuarine systems include subsidence and sea-level rise.

Impact-Level Definitions

For this analysis, the following definitions were used to categorize impacts to wetlands and 

submerged vegetation:

• Negligible – Little to no measurable impacts in the surrounding habitat (i.e., 

wetland segment and seagrass bed).

• Minor – Noticeable but short-term and localized impacts. 

• Moderate – Damage to coastal habitats that is detectable, spatially extensive, 

but temporary and not severe.

• Major – Detectable changes in species composition and abundance and/or 

altered ecological function well beyond that of normal variability. Changes would 

likely be both long-lasting and spatially extensive for such an effect.

4.3.1.1 Description of the Affected Environment

Wetlands

A recent evaluation of wetland trends in the U.S. covering the period from 2004 to 2009 

indicated that in 2009 there were 15.4 million ac (6.2 million ha) of coastal wetlands (including 

saltwater and freshwater wetlands) in the GOM region, a downward trend of 257,150 ac 

(104,065 ha) (Dahl and Stedman, 2013). In 2009, there were approximately 3.35 million ac 

(1.35 million ha) of intertidal wetlands in the GOM coastal region, which was a decline of 

approximately 2.8 percent since 2004 and represents 99 percent of all intertidal wetland losses 

across the three coastal regions of the conterminous U.S. These losses have been attributed to the 

effects of severe coastal storms, land subsidence, sea-level rise, and the construction of levees 

along the Mississippi River. In coastal Louisiana and Texas, oil, gas, and groundwater extractions 

have contributed to subsidence and relative sea-level rise (Dahl, 2011). A small percentage is 

attributed to discrete anthropogenic actions (Dahl and Stedman, 2013).

An estimated 3.9 million ac (1.6 ha) of wetlands existed on the Texas coast in 1992. 

Approximately 210,600 ac (85,227 ha) had been lost since 1955. Approximately 1.7 million ac 

(687,966 ha) or 52 percent of the freshwater wetlands were classified as farmed wetlands. The 

greatest losses were of freshwater emergent and forested wetlands (Moulton et al., 1997). The 

major cause was faulting and land subsidence due to the withdrawal of underground water and oil 

and gas (onshore), which has resulted in the submergence of marshes (Moulton et al., 1997).

Coastal Louisiana, which contains about 37 percent of the estuarine herbaceous marshes in 

the conterminous U.S. and which supports the largest commercial fishery in the lower 48 States 
Description of the Affected Environment and Impact Analysis 4-53

(Chapter 4.10), currently accounts for about 90 percent of the total coastal wetland loss in the 

continental U.S. (Couvillion et al., 2011). Coastal Louisiana has undergone a net change in land

area of about -1,883 mi2

 (-4,877 km2) from 1932 to 2010. Ninety-five percent of this loss is due to 

continual loss of land through subsidence, saltwater intrusion, and other factors. The wetland loss 

rate for Louisiana has slowed from 42 mi2

/yr (27,000 ac/yr) during the late 1960’s to a rate of 

16.57 mi2 (43 km2

) per year from 1985 to 2010 (Couvillion et al., 2011).

In 1999, Mississippi had approximately 64,000 ac (25,900 ha) of vegetated coastal wetlands 

(Mississippi Department of Marine Resources, 1999). Estuarine wetlands are common in 

Mississippi and include marshes, mud flats, and forested wetlands. The estuarine marshes around 

Mississippi Sound and associated bays occur in discontinuous bands. The most extensive coastal 

wetland areas in Mississippi occur in the eastern Pearl River delta near the Louisiana/Mississippi 

border and in the Pascagoula River delta area near the Mississippi/Alabama border. Mississippi’s 

wetlands seem to be more stable than those in Louisiana and Alabama (Mississippi Department of 

Marine Resources, 1999; Wallace, 1996; Couvillion et al., 2011). Urban and suburban growth are 

suggested as the greatest contributors to direct coastal wetland loss in Mississippi and Alabama.

Alabama has approximately 118,000 ac (47,753 ha) of coastal wetlands. Between 1955 and 

1979, 69 percent of the freshwater marsh and 29 percent of the estuarine marsh were lost (Wallace, 

1996). Most coastal wetlands in Alabama occur on the Mobile River Delta or along the northern 

Mississippi Sound. Both Mississippi and Alabama have estuarine intertidal emergent habitats that 

include salt marsh, as well as intertidal forested/shrub that can include mangroves and other salttolerant shrubs. Urban and suburban growths are suggested as the greatest contributors to direct 

coastal wetland loss in Mississippi and Alabama.

Florida wetlands, at one time estimated to encompass over 20 million ac (8.1 million ha), 

have been converted through draining, dredging, filling, and flooding, until by 1996, approximately 

11.4 million ac (4.6 million ha) remained (Dahl, 2005). Wetland loss rates in Florida, as high as 

72,000 ac (29,137 ha) per year from the mid-1950’s to the mid-1970’s, declined by nearly 80 percent 

to 5,000 ac (2,023 ha) per year between 1985 and 1996. This decline was due largely to increased 

regulation and elimination of incentives for wetland drainage. Public education, protection programs, 

and policies that promoted wetland restoration and creation also contributed (Dahl, 2005).

Florida’s salt marshes are most abundant on its central and northern coastlines (Mitsch and 

Gosselink, 2000). They are dominant along the Big Bend area of the Gulf Coast in low-energy 

shorelines, sands, lagoons, and bays. Florida’s coastal zone contained approximately 21 percent of 

the estuarine and marine wetlands of the conterminous U.S. and 92 percent of estuarine shrub 

wetlands in 1996.

Coastal wetlands and barrier islands are complex systems that provide many important 

functions. One of these functions is as a front line of defense against storm surge. High organic 

productivity and efficient nutrient recycling are characteristic of coastal wetlands. These wetland 

corridors provide habitat for a great number and wide diversity of resident plants, invertebrates, 
4-54 Gulf of Mexico Multisale EIS

fishes, reptiles, birds, and mammals. Marsh environments are particularly important nursery 

grounds for many economically important fish and shellfish juveniles. The marsh edge, where 

marsh and open water come together, is particularly important for its higher productivity and greater 

concentrations of organisms. Emergent plants produce the bulk of the energy that supports saltmarsh dependent animals.

The intensity and frequency of hurricanes in the GOM in recent years has greatly impacted 

the system of protective barrier islands, beaches, and dunes and associated wetlands along the Gulf 

Coast. Gulf shorelines have lost existing beach dunes and have experienced a decrease in beach 

ridge elevations, and barrier islands and wetlands have lost acreage to wave erosion due to 

hurricanes. As a result of decreased dune and barrier island elevations, as well as associated 

marshes and backshore and foreshore wetlands, the inland coasts and wetlands are more 

vulnerable to future hurricanes and wind-driven tidal or storm events.

The Deepwater Horizon oil spill was the largest spill ever recorded in the GOM and resulted 

in the oiling of an extensive portion of the northern Gulf Coast shoreline from the Texas/Louisiana 

State line to northwest Florida (Florida Panhandle) (OSAT-2, 2011). Oil from the Deepwater Horizon

explosion and oil spill was documented to have stranded on approximately 495 mi (796 km) of 

marsh shoreline. In most areas, the oil stranded along the marsh edge, usually spreading into the 

marsh no more than about 33-49 ft (10-15 m) perpendicular to the shoreline. Cleanup activities 

were conducted on 8.9 percent of the affected marsh (Michel et al., 2013). Various cleanup 

techniques were employed, but as of 2012, recovery was not complete and negative effects were

ongoing (Zengel et al., 2015).

Submerged Aquatic Vegetation

Submerged aquatic vegetation can be defined as the collection of benthic plants that settle 

and grow in the marine and estuarine waters but that do not emerge from it. Distribution and 

composition of the species present depend on an interrelationship among a number of 

environmental factors, including water temperature, depth, turbidity, salinity, turbulence, and 

substrate suitability (Kemp, 1989; Onuf, 1996; Short et al., 2001). In high salinity waters, submerged 

aquatic vegetation are marine seagrasses that generally occur in relatively shallow and clear 

protected waters with substrates firm enough to enable colonization (Short et al., 2001). For 

estuarine waters with low salinity, submerged aquatic vegetation may include several species of 

vegetation typically considered to be freshwater species but are tolerant of low levels of salinity 

(Castellanos and Rozas, 2001). In the higher salinity waters of the GOM, there are five true 

seagrass species and one similar species, although not technically a true seagrass (Zieman, 1982; 

Short et al., 2001; Berns, 2003; Handley et al., 2007; Cho and May, 2008). Where salinity is lower, 

there are four genera that routinely comprise the community (Castellanos and Rozas, 2001; Cho and 

May, 2008). Submerged vegetative habitats are important in carbon sequestration, nutrient cycling, 

and sediment stabilization (Heck et al., 2003; Duarte et al., 2005; Orth et al., 2006; Frankovich et al., 

2011). Submerged vegetation functions as an important habitat for many species by providing 

protection from predation. It also provides food resources for associated infaunal species, nekton, 
Description of the Affected Environment and Impact Analysis 4-55

and other megaherbivores and over wintering waterfowl (Rozas and Odum, 1988; Rooker et al., 

1998; Castellanos and Rozas, 2001; Heck et al., 2003; Orth et al., 2006; Maiaro, 2007). One of the 

more important functions of submerged aquatic vegetation systems is the transfer of primary 

production from epiphytic algae into the ecosystem via grazing of those epiphytes by secondary 

consumers; however, without grazers, excessive epiphyte growth can become a hindrance to growth 

(Howard and Short, 1986; Bologna and Heck, 1999; Heck et al., 2006).

According to the most recent and comprehensive data available, approximately 1.25 million 

ac (500,000 ha) of seagrass beds are estimated to exist in exposed, shallow coastal/nearshore 

waters and embayments of the GOM; over 80 percent of these beds are in Florida Bay and Florida 

coastal waters (calculated from Handley et al., 2007). In the northern GOM from south Texas to 

Mobile Bay, seagrasses occur in relatively small beds behind barrier islands in bays, lagoons, and 

coastal waters (Figure 4-11), while freshwater submerged aquatic vegetation occurs in the upper 

regions of estuaries and rivers (Onuf, 1996; Castellanos and Rozas, 2001; Handley et al., 2007). 

Increased nutrients and sediments from natural (e.g., tropical cyclones) or anthropogenic events 

(e.g. nutrient loading, sedimentation, and declining water quality) are common and are a significant 

cause of seagrass declines worldwide (Orth et al., 2006; Carlson and Madley, 2007; Waycott et al., 

2009). The USGS’s Seagrass Status and Trends in the Northern Gulf of Mexico: 1940-2002

demonstrated a decrease of seagrass coverage across the northern Gulf of Mexico from the bays of 

Texas to the Gulf shores of Florida; this loss was from approximately 1.02 million ha (2.52 million ac) 

estimated in 1992 to approximately 500,000 ha (1.25 million ac) calculated in the 2002 report 

(Handley et al., 2007). While declines have been documented for different species in different 

areas, it is difficult to estimate rates of decrease because of the fluctuation of biomass among the 

different species seasonally and yearly.

Figure 4-11. Seagrass Locations of the Northern Gulf of Mexico.
4-56 Gulf of Mexico Multisale EIS

These coastal habitats also play an important role to ESA-listed species; BOEM consults on 

these species with the FWS and NMFS. These species include nearshore fishes, sea turtles, beach 

mice, and birds; to read about the protected species that use these habitats, refer to Chapters 4.7

(Fish and Invertebrate Resources), 4.9.2 (Sea Turtles), 4.9.3 (Beach Mice), and 4.9.4 (Protected 

Birds).

4.3.1.2 Environmental Consequences

Routine Activities

Impact-producing factors and scenarios for routine operations can be found in Chapter 3.1. 

In this chapter, consideration is given to impacts to coastal wetlands and marshes from routine 

activities associated with a proposed lease sale. The primary impact-producing factors associated 

with a proposed lease sale that could affect wetlands and marshes include pipeline emplacement, 

construction, and maintenance; navigation channel use (vessel traffic) and maintenance dredging; 

disposal of OCS oil- and gas-related wastes; and use and construction of support infrastructure in 

these coastal areas.

Pipeline Emplacement

Many existing OCS pipelines make landfall on barrier island and wetland shorelines 

(Chapter 3.1.3.3). Approximately 4,971 mi (8,000 km) of OCS oil- and gas-related pipelines cross 

marsh and upland habitat in Louisiana (USDOI, MMS, 2007). Wetlands protect pipelines from 

waves and help to keep the lines buried and in place. At least two studies have shown a connection 

between land loss and existing pipelines. One study indicated that existing pipelines have caused 

direct land loss averaging 6 ac (2.43 ha) per linear km of pipeline for the 1955-1978 time period 

(Bauman and Turner, 1990). Bauman and Turner (1990) also indicated that the widening of OCS 

pipeline canals does not appear to be an important factor for total net wetland loss in the coastal 

zone because few pipeline canals are open to navigation. In contrast, Johnston et al. (2009) found 

that land loss was consistently higher in the vicinity of pipelines compared with more general, 

regional trends of land loss, suggesting that they contributed to the loss.

Modern pipeline construction typically employs horizontal, directional (trenchless) drilling 

techniques and open-water routes to the extent possible to avoid damages to estuarine systems 

(i.e., emergent wetlands and submerged vegetation beds) and beaches. Similar features are now 

commonly required to minimize any impacts from pipeline landfalls. Currently, no new construction 

of flotation canals (the most harmful construction technique) is being allowed in vegetated areas 

(Johnston et al., 2009). There is only 0-1 pipeline landfalls projected to result from a proposed 

action. About 12-20 ac (5-8 ha) of land loss for the projected 1.2 mi (2 km) of pipeline (based on 

historic loss rates) are expected from a proposed action. This represents approximately 

0.19 percent of the total land loss estimated to occur along the Louisiana coast in 1 year (Couvillion 

et al., 2011). This estimate does not take into account mitigating measures from the present 

regulatory programs of Federal or State agencies, modern installation techniques, and the Federal 

“no net loss” policy. These programs and techniques include compensatory mitigations and less 
Description of the Affected Environment and Impact Analysis 4-57

destructive construction methods among others. Because of the regulations and new construction 

methods, and the limited projection for, at most, one new pipeline landfall, pipeline emplacement 

would be expected to result in zero to negligible impacts to estuarine habitats.

Five pipeline installation techniques are used throughout the coastal zone of the Gulf of 

Mexico: upland trenching; jetting; building flotation canals; push-pull ditching; and directional drilling. 

Of these, flotation canals have the most harmful effects. Push-pull ditching can also be used to 

effectively minimize wetland impacts when postconstruction mitigation methods such as backfilling 

are used (Johnston et al., 2009). Trenchless, or directional drilling, is the newest and favored 

technique in sensitive habitats. This technique is considered to be extremely protective of sensitive 

habitats. At present, directional drilling is required almost without exception for crossing barrier 

island and shore faces. Impacts are limited to the access and staging sites for the equipment. By 

using directional drilling, pipeline installation can occur without having to cut through shore facings, 

minimizing any erosion and surface habitat disturbance.

Because of the modern installation techniques and mitigations, the small number of 

projected pipeline landfalls, and the present regulatory programs of the COE and the Gulf Coast 

States, impacts to wetlands and other estuarine areas from pipeline emplacement associated with a 

proposed lease sale are expected to be negligible. 

Dredging

Maintenance dredging of navigation channels and canals is expected to occur with minimal 

impacts to wetlands. It is assumed that the need for maintenance dredging is proportional to the 

percentage of the vessel traffic; therefore, a proposed lease sale is expected to only contribute 

minimally to the need for this dredging, accounting for less than 2 percent, of all traffic using 

navigation channels in the GOM (Chapter 3.1.4.6; Tables 3-2 and 3-6). Thus, vessel traffic related 

to a proposed action is only a small portion of the traffic that would require maintenance dredging of 

channels. However, occasionally a channel would be dredged ahead of its normal maintenance 

schedule in order to accommodate the transport of large OCS platforms. Beneficial use of dredged 

material can be used to enhance and create coastal wetlands after material has been tested for the 

presence of contaminants. The COE’s New Orleans District annually removes approximately 

46-53 million m3 (60-70 million yd3

) of dredged material from 10 Federal navigation channels 

throughout coastal Louisiana, and approximately 26 percent of this material is used for coastal 

wetland restoration projects (Creef, official communication, 2011). As a result of the tremendous 

wetlands land loss in the Louisiana coastal region, the beneficial use of dredged material is expected 

to increase. Executive Order 11990 (1977) requires that, where appropriate, material from 

maintenance dredging be considered for use as a sediment supplement in deteriorating wetland 

areas to enhance and increase wetland acreage. Given the COE‘s policy of beneficial use of 

dredged material, increased emphasis has been placed on the use of dredged material for marsh 

creation.
4-58 Gulf of Mexico Multisale EIS

Despite the beneficial uses described above, dredging and dredged-material disposal can 

also be detrimental to coastal environments and associated fish and wildlife that use the affected 

areas for nursery grounds and protection. These impacts may include increased erosion rates, 

removal of sediments, increased turbidity, and changes in salinity (Onuf, 1996; Kenworthy and 

Fonseca, 1996; Erftemeijer and Lewis, 2006). Many of these impacts are reduced through the use 

of modern disposal practices.

Because of the mitigations and regulations connected with coastal dredging operations, the 

impacts outlined above are expected to only occur in localized areas over a short amount of time; 

therefore, the overall level of impact to coastal communities is minor. Therefore, due to the small 

contribution of a proposed action to the need for dredging, impacts to coastal habitats from a 

proposed action are expected to be negligible. 

Navigation Channels and Vessel Traffic

Most navigation channels projected to be used to support a proposed action are currently 

used by vessels that support the OCS Program (Chapter 3.1.4.6; Table 3-6). Approximately 

1,988 mi (3,200 km) of OCS oil- and gas-related navigation canals, bayous, and rivers are found in 

the coastal regions around the GOM. This is exclusive of channels through large bays, sounds, and 

lagoons. No new navigation channels are expected as a result of a proposed action, although 

channels within ports may be created or enlarged. Ports that have navigation channels deep 

enough to accommodate deeper-draft vessels may expand their infrastructure to accommodate 

deeper-draft vessels. An example of a significant expansion of a service base is Port Fourchon in 

coastal Louisiana. Port Fourchon has deepened the existing channel and has dredged additional 

new channels to facilitate the expansion. Port Fourchon currently services approximately 90 percent 

of all deepwater rigs and platforms in the GOM (Loren C. Scott and Associates, 2008), and 

approximately half of all offshore service vessel trips from 2012 through 2017 are expected to 

emanate from there (Kaiser, 2015b).

Vessel traffic that may support a proposed action is discussed in Chapter 3.1.4.4. Waves 

generated by boats, ships, barges, and other vessels erode unprotected shorelines and accelerate 

erosion in areas already affected by natural erosion processes. Much of the service-vessel traffic 

that is a necessary component of OCS oil- and gas-related activities uses the channels and canals 

along the Louisiana coast. The most heavily used OCS navigation channel is the channel from Port 

Fourchon to the GOM, which is heavily armored and is less erodible. Recent studies have found 

that armored canals have reduced loss rates compared with unarmored canals (Johnston et al., 

2009; Thatcher et al., 2011) and that widening rates have slowed based on maintenance techniques. 

A recent BOEM and USGS-funded study (Thatcher et al., 2011) examined the susceptibility to 

erosion of navigation channels based on cover and substrate. They found that canal erosion rates 

have slowed in recent years. Indirect impacts from wake erosion and saltwater intrusion are 

expected to result in minor impacts, which are indistinguishable from direct impacts from inshore 

activities.
Description of the Affected Environment and Impact Analysis 4-59

A proposed action is estimated to contribute <2 percent of the total OCS traffic from 2017 

through 2066 (Tables 3-2 and 3-6). Further details concerning vessel traffic can be found in 

Chapter 3.1.4.4. Navigation channels projected to be used in support of a proposed action are 

discussed in Chapter 3.1.4.6. According to BOEM’s calculations, all estimated navigational use 

(both OCS and other) is expected to contribute approximately 336 ha/yr (831 ac/yr) of land loss per 

year. However, given the relatively small percentage of vessel traffic from OCS oil- and gas-related 

activities, in combination with ongoing armoring and regular maintenance along the waterways, only 

negligible impacts related to the vessel traffic would result from a proposed action.

Disposal of OCS-Related Wastes, Trash, and Debris

Produced sands, oil-based or synthetic-based drilling muds and cuttings, along with fluids 

from well treatment, workover, and completion activities, would be transported to shore for disposal 

(Chapter 3.1.5). Sufficient disposal capacity is expected to be available in support of a proposed 

action (Chapter 3.1.7.2.7). Produced-water discharges from OCS wells would be too distant from 

coastal habitats to have anything more than negligible impacts. Because of wetland-protection 

regulations, no new waste disposal sites are expected to be developed in wetlands. Some seepage 

or discharges from existing waste sites into adjacent wetland areas may occur and toxic wastes 

could kill wetland plants, but such seepage is not expected to be widespread.

Trash and debris can be an issue for estuarine communities in that the fauna in these areas 

could ingest or become entangled in the trash and debris. BOEM and BSEE have addressed the 

marine debris issue by imposing marine debris awareness and prevention measures on the oil and 

gas industry through NTL 2015-BSEE-G03, which provides guidance to the industry operators 

regarding dumping trash and debris into the marine environment and informs operators of 

regulations set by other regulatory agencies (i.e., the USEPA and USCG). Because of the 

mitigations and awareness, OCS oil- and gas-related trash and debris from a proposed action would 

result in negligible impacts to estuarine habitat.

Onshore Facilities

Various kinds of onshore facilities service OCS development. All projected new facilities that 

are attributed to the OCS Program and a proposed action are described in Chapter 3.1.7. State and 

Federal permitting agencies discourage the placement of new facilities and the expansion of existing 

facilities in wetlands. However, any large construction project in the coastal zone is likely to impact 

some wetland acreage. Any impacts upon wetlands are mitigated in accordance with the Clean 

Water Act requirements and the COE’s 404 permit and State permitting programs. The high cost of 

wetland mitigation discourages industry from causing damage to wetlands when building onshore 

facilities. Since no new facilities are estimated with a proposed action and any possible impacts 

would be mitigated, the impact level from the associated factors discussed above would be 

negligible. 
4-60 Gulf of Mexico Multisale EIS

Accidental Events

A detailed description of the impact-producing factors and scenario for accidental events 

from a proposed action are given in Chapter 3.2. There is also a risk analysis of accidental events 

in Chapters 3.2.1. The main impact-producing factors that would affect wetlands are oil spills. 

Chemical spills could also potentially affect wetlands, but they are rare (Table 3-21).

Both coastal and offshore oil spills can be caused by large tropical storm events, faulty 

equipment, or human error. The degree of coastal impact is a function of the source oil type, 

volume, and condition of the oil as it reaches shore, along with the season of the spill and the 

composition of the wetland plant community affected. Barrier island loss due to hurricanes and 

anthropogenic factors has reduced protection of wetlands from offshore oil spills, and thus, there is a 

greater potential for the oiling of coastal wetlands during an accidental event. Refer to the 

Catastrophic Spill Event Analysis white paper for an analysis of impacts from a low-probability 

catastrophic spill event (USDOI, BOEM, 2016c).

Primary Impacts of Oil Spills

The widespread distribution of OCS oil- and gas-related activity reduces the probability of 

toxic oil reaching coastal wetlands. The OCS production facilities are located at least 3 nmi (3.5 mi; 

5.6 km) from coastal wetlands, and much of the OCS oil- and gas-related activity is much farther. 

Recent trends towards drilling in deeper water have increased the proportion of OCS oil- and gasrelated activity in distant locations, many of which are well over 100 nmi (115 mi; 185 km) offshore. 

This allows for the toxicity of spilled oil from offshore to be greatly reduced or eliminated by 

weathering and biodegradation (OSAT-2, 2011).

Coastal Spills

The greatest threat to estuarine habitat with regards to an oil spill is from a coastal spill 

resulting from a vessel accident or pipeline rupture. These spills are a concern since they would be 

much closer to the estuarine resources. Resulting contact would likely be greater, and toxicity would 

tend to be greater due to reduced weathering of the oil. While a resulting slick may cause impacts to 

estuarine habitat, the cleanup effort (i.e., equipment, chemicals, and personnel) can generate 

additional impacts to the area. Associated foot and vehicular traffic may work oil farther into the 

sediment than would otherwise occur. Further, physical prevention methods such as booms, barrier 

berms, and diversions can alter hydrology, specifically changing salinity and water clarity. These 

changes could cause mortality or reduced productivity in certain species of submerged vegetation

because they are only tolerant to certain salinities and light levels (Zieman et al., 1984; Kenworthy 

and Fonesca, 1996; Frazer et al., 2006). Close monitoring and restrictions on the use of bottomdisturbing equipment would be needed to avoid or minimize those impacts.

Numerous investigators have studied the immediate impacts of oil spills on GOM coastal 

habitats and elsewhere. Often, seemingly contradictory conclusions are generated from these 

impact assessments. These contradictions can be explained by differences in parameters, including 
Description of the Affected Environment and Impact Analysis 4-61

oil concentrations and chemical composition, season or weather, vegetation type and density, 

whether the area is in a low- or high-energy environment, preexisting stress level on the vegetation, 

soil types, anoxic condition of the soil, and water levels. Data indicate that vegetation that is lightly 

oiled would experience plant die-back, followed by recovery without replanting; therefore, most 

impacts from light oiling to vegetation are considered to be short term and reversible (Lytle, 1975; 

DeLaune et al., 1979; Webb et al., 1985). However, Alexander and Webb (1987) noted erosion of 

the shoreline in areas affected with high oil content and Fischel et al. (1989) found that, while some 

oiled marsh areas showed recovery of vegetation a year after a spill, other areas had converted to 

mud flats or open water.

Oil has been found or estimated to persist for at least 17-20 years in low-energy 

environments like salt marshes (Teal et al., 1992; Baker et al., 1993; Burns et al., 1993; Irvine, 

2000). If thick oil is deposited on marsh in low-energy environments, effects on marsh vegetation 

can be severe and recovery can take decades (Baca et al., 1987; Baker et al., 1993). The sediment 

type, the anoxic condition of the soils, and whether the area is in a low- or high-energy environment 

all play a part in the persistence of oil in marsh sediment (Teal and Howarth, 1984), so different 

shorelines exhibit varying levels of oil persistence (Hayes et al., 1980; Irvine, 2000). Oil is more 

persistent in anoxic sediments and, as a result of this longer residence time, has the potential to do 

damage to both marsh vegetation and associated benthic species. Batubara et al. (2014) found that 

PAH degradation is higher in intertidal than in subtidal wetland soils. For submerged vegetation the 

same is true, and oil can cause decreased water clarity from coating and shading could cause 

reduced chlorophyll production and could lead to a decrease in vegetation (Erftemeijer and Lewis, 

2006).

Cleanup activities in marshes that can last years to decades following a spill may accelerate 

erosion rates and retard recovery rates. While oil can completely foul wetland plants, it is the 

amount and type of oil, as well as the particular plant that determines recovery. Pezeshki et al. 

(2000) found that Louisiana crude oil was less damaging and fatal to Spartina alterniflora marsh 

grass than the heavier crudes. Heavy oiling can stop photosynthetic activity, but the S. alterniflora

produced additional leaves and was able to recover without shoreline cleanup. Except in areas of 

heavy oiling, it is better to let wetland areas recover naturally (Zengel et al., 2014).

Numerous studies have demonstrated that different species of plants respond differently to 

oiling. Lin and Mendelssohn (1996) found that Louisiana crude oil applied to three species of marsh 

plants resulted in no regrowth after 1 year in applications for Spartina alterniflora and S. patens, but 

resulted in increased regrowth with increased oil application for Sagittaria lancifolia. Kokaly et al. 

(2011) found that, where the predominant marsh grass is tall (Phragmites australis) and less 

susceptible to being completely oiled, damage is minimized. Judy et al. (2014) also found high 

tolerance of P. australis to weathered and emulsified oil. Coastal marshes impacted by crude oil 

were observed to show evidence of recovery within 1 year after oil was stranded and covered 

vegetation, with shoot production observed in heavily oiled areas, although depending on vegetation 

type, the amount of recovery varied (Delaune and Wright, 2011). When a spill contacts wetlands, an 

impact from the resulting depletion of marsh vegetation is increased and accelerated erosion, and 
4-62 Gulf of Mexico Multisale EIS

resulting land loss (Alexander and Webb, 1987). Another study documented increased erosion at 

highly oiled sites 26 months after a spill (McClenachan et al., 2013).

Some OCS oil- and gas-related pipelines traverse wetland areas, and pipeline accidents 

could result in high concentrations of oil directly contacting localized areas of wetland habitats 

(Fischel et al., 1989). In a study of a coastal pipeline break by Mendelssohn et al. (1993), a 300-bbl 

spill of Louisiana crude oil impacted 49 ac (20 ha) of wetlands, resulting in considerable short-term 

effects on the brackish marsh community. While considerable die out of the marsh was noted, 

recovery of the marsh was complete within 5 years despite the residual hydrocarbons that were 

found in the marsh sediment. The study also noted that the health of the recolonizing vegetation 

was not significantly different from the health of vegetation found in the areas that were not oiled. 

Patterns of land loss were spatially variable, but the rate of loss in the oiled areas was similar to that 

of the unaffected areas (Mendelssohn et al., 1993).

BOEM’s analysis shows that 96 percent of reasonably foreseeable spills from OCS oil-and 

gas-related activity are <1 bbl, with an average size of <0.05 bbl (Anderson et al., 2012). Because 

of the small contribution to all such spills from the proposed action, the small size of most spills, and 

with current safety measures and cleanup guidance in place, the impacts from the impact-producing 

factors of a coastal spill are expected to be minor for estuarine communities.

Offshore Spills

The probabilities of an offshore spill ≥1,000 bbl occurring and contacting environmental 

features are described in Chapter 3.2.5.8. In addition, the results of a risk analysis estimating the 

likelihood of a spill <1,000 bbl occurring and contacting environmental resources (including 

wetlands) can be found in Chapter 3.2.1.6.4. Most spills from the OCS are likely to be distant 

enough that, should a slick from such a spill make landfall, the volume of oil remaining in the slick is 

expected to be small. This is because the distance of the spill to the coast allows oil to evaporate, 

break down, and disperse. Also, due to the tidal flushing on the coast, a slick would be broken down 

further. However, should spills from the OCS occur proximate to State waters, they could reach 

shore before much weathering, evaporation, or dispersal had occurred. The probabilities of oil spills 

≥1,000 bbl occurring and contacting coastal shorelines varies by location, with the highest probability 

as a result of a proposed action estimated at 8 percent for one location; for most locations, it was 

<0.5-1 percent (Figure E-20).

Because of the small contribution to all such spills from the proposed action, the distance 

from coastal communities, improved technologies, and the dynamic nature of the coastal 

environment, offshore spills are expected to have a minor impact on the estuarine community.

Spills that occur in or near Chandeleur Sound or Mississippi Sound could affect estuarine 

habitat in the Gulf Islands National Seashore (135,458 ac; 545,818 ha), including its Wilderness 

Area (4,080 ac; 1,651 ha), and the Breton National Wildlife Refuge (18,273 ac; 7,395 ha) with its 

Wilderness Area (5,000 ac; 2,023 ha). Although the wetland acreage on these islands is small, the 
Description of the Affected Environment and Impact Analysis 4-63

wetlands and associated communities make up an important element in the habitat of the islands. 

The inlets that connect Mississippi Sound with the marsh-fringed estuaries and lagoons within the 

islands are narrow; therefore, a small percentage of the oil that contacts the Sound side of the 

islands would be carried by the tides into interior lagoons.

Secondary Impacts of Oil Spills

The short-term effects of oil on wetland plants range from reduction in transpiration and 

carbon fixation to plant mortality. Depending on the type and quantity of oil in the sediment, 

mineralization of nutrients can be blocked so that there is less nutrient uptake from the soils. The 

potential impact of the oiling on the wetland habitats is dependent on several factors, including 

season. In general, most wetland plants are more susceptible to impacts from oiling during the 

growing season. Heavy oil causes mortality by coating gas exchange surfaces on the plants and by 

sealing sediment, which limits nutrient exchange to below-ground tissue. Light weight oils have 

been found to be more toxic to various marsh plants and associated organisms because the oil 

alters membrane permeability and disrupts metabolism (Pezeshki et al., 2000). Due to the 

difference in oil tolerances of various wetland plants, changes in species composition may be 

evident as a secondary impact of the spill (Pezeshki et al., 2000). Studies indicated that some 

dominant freshwater marsh species (Sagittaria lancifolia) are tolerant to oil fouling and may recover 

without being cleaned (Lin and Mendelssohn, 1996). Secondary impacts can also include impacts 

caused by cleanup activities, as discussed below. Because these secondary impacts would not 

noticeably affect GOM coastal plant communities as a whole, impacts are expected to be minor. 

Cleanup Activities

Current methods to clean up oil spills include mechanical removal, in-situ burning, and 

bioremediation (refer to Chapter 3.2.7 for more information). Generally speaking, unless the oiling 

is extremely heavy, the best approach has been to avoid measures that would further drive oil into 

the sediment (e.g., vessel and foot traffic) or damage vegetation. Often that means it is best to do 

nothing and let nature take its course. Oil spill cleanup in coastal marshes remains a problematic 

issue because wetlands and submerged vegetation can be extremely sensitive to the disturbances 

associated with cleanup activities. Once a marsh is impacted by an oil spill, a decision must be 

made concerning the best method of clean up and restoration. Often the best course of action is to 

let the impacted area(s) recover naturally in order to avoid secondary impacts associated with the 

cleanup process, such as trampling vegetation, accelerating erosion, and burying oil (Long and 

Vandermeulen, 1983: Getter et al., 1984; Mendelssohn et al., 1993). In areas of thick oil deposits, 

however, a cleanup effort would result in greater recovery (Baker et al., 1993). Because oil spills 

that require cleanup can have noticeable but localized impacts, cleanup activities are expected to 

have a minor effect on the estuarine community.

Cumulative Impacts

Estuarine habitats are vulnerable to many impact-producing factors from OCS oil- and gasrelated and non-OCS oil- and gas-related impacts. Specific OCS oil- and gas-related, impact-
4-64 Gulf of Mexico Multisale EIS

producing factors considered in this cumulative analysis include the following: (1) oil spills; (2) OCS 

oil- and gas-related vessel traffic and navigation canals; (3) construction of OCS oil- and gas-related 

infrastructure and support structure (including pipelines); and (4) waste disposal. Non-OCS oil and 

gas-related, impact-producing factors would potentially impact wetland resources, including the 

following: (1) State oil and gas activities; (2) non-OCS oil- and gas-related vessel traffic and 

navigation canals; (3) coastal infrastructure and development; (4) natural processes (including 

hurricanes and subsidence); and (5) sea-level rise (natural causes of subsidence are combined with 

subsidence caused by extraction and other man made alterations). While each of these factors can 

cause negative impacts to wetlands, a proposed action would not greatly increase the overall 

impacts. 

OCS Oil- and Gas-Related Impacts

Oil Spills

The potential for coastal oil spills poses a threat for coastal habitats due to the proximity of 

the spills to these vegetated areas. Aging infrastructure including refineries, onshore production 

facilities, platforms, and pipelines would continue to be an increasing source of potential spills, but 

future spills from these types of facilities would be less likely because these older facilities are 

gradually either structurally updated or replaced by the owner/operator. 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 (not including catastrophic spills), as long as the level of energy-related 

commercial and recreational activities remains the same.

The Deepwater Horizon oil spill was the largest spill recorded in the GOM and resulted in the 

oiling of an extensive portion of the northern Gulf Coast shoreline from the Texas/Louisiana border 

to northwest Florida (Florida Panhandle) (OSAT-2, 2011). This event must be considered in the 

cumulative baseline due to the volume of oil released and the geographic area affected. In Michel 

et al. (2013), oil from the Deepwater Horizon explosion and oil spill was documented by shoreline 

assessment teams to have stranded on approximately 495 mi (796 km) of marsh shoreline. In most 

areas, the oil stranded along the marsh edge usually spreads into the marsh no more than about 

33-49 ft (10-15 m) perpendicular to the shoreline. Cleanup activities were conducted on 8.9 percent 

of the affected marsh. The most heavily oiled marshes in Barataria Bay, Louisiana, were cleaned 

using intensive manual and mechanical raking and cutting methods (Michel et al., 2013). This oil 

and the associated cleanup activities have impacted wetlands in Louisiana, Mississippi, Alabama, 

and the panhandle of Florida. While there were localized severe impacts to wetlands, many of the 

areas affected have recovered or show a moderate level of impact. The oil was released and 

treated in deep water nearly 48 mi (77 km) from shore. This contributed to the weathering and 

detoxification of the oil that reached the shoreline. It is too early to determine the cumulative longterm effect of this spill and its contribution to the ongoing marsh loss or the acceleration of that loss. 

New regulations focusing on improved safety, more regulatory checks, and inspections should 

decrease the already small likelihood of the occurrence of such spills, which are not part of a 

proposed action and not reasonably expected to occur. Potential impacts as a result of a low-
Description of the Affected Environment and Impact Analysis 4-65

probability catastrophic event are discussed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2016c).

Oil from offshore spills is less likely to reach the estuarine habitat in the same condition it 

was released due to weathering, potential dispersant treatment, and blockage by barrier islands and 

shorelines. However, erosion of these barriers by hurricanes and tropical storms has decreased the 

level of protection afforded the mainland, so flood tides could bring oil through tidal inlets (USDOC, 

NMFS, 2007a). For many spills, light oiling of vegetated wetlands may occur. Adverse impacts from 

light oiling that may occur to wetland plants are expected to be short lived, with possible plant dieback, followed by recovery without replanting (Lytle, 1975; DeLaune et al., 1979; Webb et al., 1985). 

However, spill data from the OCS show that, over decades of activity, tens of thousands of barrels of 

oil have been spilled (Chapter 3.2.1.1.3). Cumulative OCS oil- and-gas-related spills resulting from 

all past and present leasing activities are expected to have a moderate impact on the estuarine 

community. The incremental contribution to cumulative OCS oil- and gas-related spills as a result of 

a proposed action, however, are expected to be minor; due the small size of most spills, the 

distance from estuarine communities, improved technologies, and the dynamic nature of the coastal 

environment. 

Vessel Traffic

Navigation channels in the coastal areas of the GOM support both OCS oil- and gas-related 

and non-OCS oil- and gas-related vessel traffic. Waves generated by boats, ships, barges, and 

other vessels erode unprotected shorelines and accelerate erosion in areas already affected by the 

natural erosion process. BOEM conservatively estimates that there are approximately 3,013 mi 

(4,850 km) of Federal navigation channels, bayous, and rivers potentially exposed to OCS oil- and 

gas-related traffic (Table 3-6) in the GOM. Conservative show that land loss in Federal navigation 

channels from various activities could total approximately 58,137 ac (23,527 ha) and from 

cumulative OCS oil- and gas-related activities land loss could total approximately 4,480-13,606 ac 

(1,813-5,506 ha). This number is considered conservative because open waterways were included 

in the total length of Federal navigation channels, vessel size was not taken into consideration, and 

there are sources of erosion to navigation canals other than vessel traffic alone. In addition, 

approximately half of all offshore service vessel trips from 2017 through 2022 are expected to 

originate from Port Fourchon, Louisiana (Kaiser, 2015b), and the channel from the Gulf to Port 

Fourchon is mostly armored, reducing channel widening. If this reliance on Port Fourchon 

continues, the land loss related to OCS channel use would be less than that estimated above.

Coastal wetland loss is greatest in Louisiana. In the Louisiana Coastal Master Plan (State of 

Louisiana, Coastal Protection and Restoration Authority, 2012), it is estimated that up to 1,750 mi2

(4,500 km2

) of land would be lost in the next 50 years. Using BOEM’s conservative estimates of 

waterways exposed to OCS traffic in the Louisiana Coastal Area (LCA) and the average canal 

widening rate, and comparing those data to estimated land loss in Louisiana over the next 50 years, 

BOEM estimates that approximately 3.7 percent of the total land loss in Louisiana would occur due 

to saltwater intrusion, hurricanes, and vessel traffic (OCS oil- and gas-related and non-OCS oil- and 
4-66 Gulf of Mexico Multisale EIS

gas-related) in navigation canals. Because OCS oil- and gas-related vessel traffic constitutes only 

9-27 percent of the total vessel traffic in the GOM, BOEM conservatively estimates that OCS oil- and 

gas-related vessel traffic would contribute approximately 1 percent or less of the land loss in coastal 

Louisiana in the next 70 years.

The OCS oil- and gas-related vessel traffic associated with the increased number of offshore 

platforms is expected to contribute minimally to the need for maintenance dredging activity of 

navigation canals. The primary support, transfer, and production facilities used for OCS oil- and 

gas-related activities are located along armored canals and waterways, thus minimizing marsh loss. 

If new onshore transfer or production facilities would be constructed, access channels may have to 

be dredged. In the foreseeable future, there would be a continuing need for dredged material for 

coastal restoration, wetland creation, and to some extent, offshore sediments (e.g., sand, etc.) 

needed for beach restoration and hurricane protection. Alternative dredged-material disposal 

methods can be beneficially used for wetland creation or restoration as required by the COE’s 

permitting program.

Because of the small incremental increase in cumulative impacts to coastal wetlands 

associated with OCS oil- and gas-related vessel traffic and the offsetting benefits of wetland creation 

using dredged material from navigation channels, impacts are expected to be minor. 

Coastal Infrastructure and Pipelines

Projected new facilities that are attributed to the OCS Program and a proposed lease sale

would not be primarily in wetland areas, and no additional service bases, heliports, platform 

fabrication yards, shipyards, pipe-coating facilities, or refineries are expected (Chapter 3.3.1.10). 

State and Federal permitting agencies discourage the placement of new facilities or expansion of 

existing facilities in wetlands. However, any sizable coastal facility may have construction impacts in 

wetlands. Any localized impacts upon wetlands from existing facilities are expected to be mitigated 

because of the Clean Water Act permitting requirements. 

Activities that would further contribute to wetland loss include additional construction of 

access channels to shoreline staging areas and expansion of onshore and offshore facilities 

(receiving and transferring facilities or fabrication of production platforms). BOEM projects 0-1 new 

gas processing facilities and 0-1 new pipeline landfalls for a proposed action. A more detailed 

description of coastal infrastructure is provided in Chapter 4.14.1. If a new facility is constructed 

and a pipeline makes landfall, any impacts upon wetlands would be mitigated in accordance with the 

Clean Water Act requirements and the COE’s 404 permit and State permitting programs. These 

mitigations and regulatory requirements, such as avoidance and compensatory wetland mitigation, 

would result in negligible impacts to coastal habitats.

Several methods exist to further reduce the number of new pipeline landfalls and their 

cumulative impact, e.g., the addition of corrosion preventatives to the pipeline itself (reducing the 

probability of accidental leakage from aging pipelines), in combination with “tie ins” to existing 
Description of the Affected Environment and Impact Analysis 4-67

Federal or State pipelines with shore connections. While impacts are greatly reduced by mitigation 

techniques, existing pipelines were placed using older techniques and have caused, and would 

continue to cause, impacts to adjacent wetlands. Remaining impacts may include expansion of tidal 

influence, saltwater intrusion, hydrodynamic alterations, erosion, sediment transport, and habitat 

conversion (Cox et al., 1997; Morton, 2003; Ko and Day, 2004b). Pipeline maintenance activities 

that disturb wetlands are very infrequent and are mitigated through regulatory programs, including 

review by the State of Louisiana through its coastal use permit requirements and through the Clean 

Water Act Section 404 and Rivers and Harbors Act Section 10 permits.

The continued widening of OCS pipeline canals from erosion does not appear to be an 

important factor contributing to OCS oil- and gas-related direct land loss. This is because few 

pipelines are open to navigation and the impact width of these pipelines does not appear to be 

significantly different from that for pipelines closed to navigation. Based on the projected coastal 

Louisiana wetlands over 50 years (Couvillion et al., 2013), land loss resulting from new OCS pipeline 

construction represents <1 percent of the total expected loss. This estimate does not take into 

account the present regulatory programs and modern installation techniques that would be expected 

to further mitigate this potential impact. Throughout the 50-year life of a proposed lease sale, a 

majority of the already old pipeline distribution and production systems would continue to age. This 

could result in an increasingly large inventory of pipelines and support structures that would need to 

be replaced or repaired. The replacement and repair of the pipeline system may temporarily impact 

wetlands in the pipeline corridors, as crews could trample wetland plants or access would have to be 

dredged; however, if proper mitigation is implemented and maintained, impacts should be minimal 

and temporary. In the absence of the replacement of these aging pipelines, the potential risk for 

spills and leaks would increase in coastal and offshore waters. Because of the mitigations and 

regulations connected with coastal operations, the impacts outlined above are expected to only 

occur in localized areas over a short amount of time and, therefore, the overall level of impact to 

estuarine communities is minor. 

Waste Disposal

Discharge of OCS oil- and gas-related produced water is generally into offshore Gulf waters 

in accordance with NPDES permits or injected back down into wells; therefore, produced waters 

from the OCS are not expected to affect coastal wetlands (Chapter 3.3.1.8). Produced sands, oilbased or synthetic-based drilling muds and cuttings, along with fluids from well treatment, workover, 

and completion activities from OCS wells, would be transported to shore for disposal in existing 

disposal facilities approved by the USEPA for handling these materials. Because of wetlandprotection regulations, no new waste disposal site would be developed in wetlands. Some seepage 

from waste sites into adjacent wetland areas may occur and result in damage to wetland vegetation 

ranging from sublethal effects to mortality, depending on the toxicity of the waste.

Trash and debris can potentially impact coastal estuarine communities in that the fauna in 

these areas could ingest or become entangled in the trash and debris. BOEM and BSEE have 

addressed the marine debris issue by imposing marine debris awareness and prevention measures 
4-68 Gulf of Mexico Multisale EIS

on the oil and gas industry through NTL 2015-BSEE-G03, which provides a guidance to industry 

operators regarding dumping trash and debris into the marine environment and informs operators of 

regulations set by other regulatory agencies (i.e., the USEPA, USCG, and others; refer to Chapter 

4.12). Because of the distance of the sources of trash on the OCS from wetlands, mitigations, and 

awareness, OCS oil- and gas-related trash and debris would result in negligible impacts to 

estuarine habitat.

Non-OCS Oil- and Gas-Related Impacts

State Oil and Gas

Impacts are expected to occur as a result of oil spills, dredging for new pipeline canals, 

maintenance, and usage of existing rig access canals and drill slips, and for the preparation of new 

well sites related to State oil and gas activities (Chapter 3.3.2.1). Such activity has taken a 

tremendous toll on coastal wetlands, particularly in Louisiana (Turner et al., 1994). Many pipelines 

carry product from both OCS oil- and gas-related and non-OCS oil- and gas-related sources. The 

impacts from these activities are generally the same as those described in the “Routine Activities,” 

“Accidental Events,” and “OCS Oil- and Gas-Related Impacts” sections above, although these 

impacts may be more pronounced due to the proximity of oil and gas activities on State lands to 

wetlands. Another impact from State oil and gas activity is local subsidence. This subsidence may 

be due to the extraction of large volumes of oil and gas, sulfur, and salt from subsurface reservoirs 

(Morton, 2003; Morton et al., 2002 and 2005), but subsidence associated with this factor seems to 

have slowed greatly over the last three decades as the reservoirs are depleted. Subsidence leads to 

the drowning of marsh plants and conversion to open water. Because of the continued effects of the 

extensive dredging of canals through coastal wetlands, impacts from State oil and gas activities are 

expected to be major. 

Vessel Traffic and Navigation Canals

Non-OCS oil- and gas-related vessel traffic in the GOM includes commercial shipping, 

support for State oil and gas activities, commercial and recreational fishing vessels, pleasure 

boating, and other types of traffic (Chapter 3.3.2.2). Waves generated by boats, ships, barges, and 

other vessels erode unprotected shorelines and accelerate erosion in areas already affected by the 

natural erosion process. In many cases, this erosion results in wetland loss. Submerged vegetation 

communities can be damaged by boat anchors, keels, and propellers, and by activities such as 

trampling, trawling, and State oil- and gas-related or scientific seismic surveys (Sargent et al., 1995; 

Dunton et al., 1998). Navigation channels require routine maintenance dredging. Minor adverse 

impacts on wetlands from maintenance dredging are expected because the large majority of the 

material would be either used to enhance or create marsh, or disposed upon existing disposal areas.

Net land loss due to navigation canals alone can be calculated by comparing erosion rates 

with beneficial activities such as land gained through the use of dredged sands; refer to the 

estimates in “OCS Oil- and Gas-Related Impacts” section above.
Description of the Affected Environment and Impact Analysis 4-69

Wetland losses may be generated by the secondary impacts of saltwater intrusion, flank 

subsidence, freshwater-reservoir reduction, and deeper tidal penetration. Navigation channels 

contribute to the negative impacts from saltwater intrusion (Gosselink et al., 1979; Wang, 1987). 

Wang (1987) developed a model demonstrating that, under certain environmental conditions, 

saltwater penetrates farther inland in deep navigation channels than in shallower channels, 

suggesting that navigation channels act as “salt pumps.” This change in salinity results in a 

substantial habitat transition from freshwater to brackish water, then to saltwater, and ultimately to 

open-water systems. An example is the construction of the Mississippi River Gulf Outlet, which 

transformed many of the cypress swamps east of the Mississippi River below New Orleans into open 

water or areas largely composed of marsh vegetation (Spartina spp.) among dead cypress tree 

trunks. This channel was closed in 2009, and further saltwater intrusion through it has been 

curtailed.

Onshore activity that would contribute to wetland loss includes additional construction of 

access channels (for instance at fabrication yards) and onshore construction of new well sites and 

the expansion or construction of onshore production facilities or receiving and transferring facilities. 

Most of these facilities would be located in Louisiana. Management activities, including erosion 

protection and restoration along the edges of these canals, can significantly reduce canal-widening 

impacts on wetland loss (Johnston et al., 2009; Thatcher et al., 2011). Because of the large 

contribution to total vessel traffic from non-OCS oil- and gas-related sources, the secondary impacts 

of navigation canals, such as saltwater intrusion, and the continuing impacts of existing access 

channels, the impacts from non-OCS oil- and gas-related vessel traffic and related activities are 

expected to be moderate. 

Coastal Infrastructure and Development

The development of estuarine habitat for agricultural, residential, industrial, commercial, and 

silvicultural (forest expansion) uses (Chapter 4.14.1) would continue but with more regulatory and 

planning constraints required under the Clean Water Act and other regulations. Impacts from these 

developments, such as alteration to habitat or hydrology, are expected to continue as development 

in coastal regions around the GOM continues.

Urban and rural development was an important factor in wetland loss in coastal watersheds 

from 1998 through 2004 (Stedman and Dahl, 2008; Dahl and Stedman, 2013). Agricultural, 

residential, industrial, and commercial developments, including recreational and tourist 

developments, have been particularly destructive to coastal wetlands in the GOM by altering habitat 

and hydrology, which can contribute to the loss of wetland ecosystems through mechanisms such as 

the addition of pollutants, creating or widening channels, or physical removal of habitat. Indirect 

effects of such development can include expansion of supporting infrastructure, including roads, 

bridges, and utilities, with related impacts similar to those mentioned above.

Infrastructure that serves the transportation of foreign oil, such as oil ports, can have wetland 

impacts to the extent that it is constructed on or adjacent to wetlands. The current regulatory 
4-70 Gulf of Mexico Multisale EIS

programs, modern construction techniques, and mitigations have reduced recent impacts to 

wetlands from pipeline installation. The continued presence of existing pipelines can contribute to 

wetland loss (Johnston et al., 2009). Oil spills caused by leaking or broken pipelines can also impact 

wetlands.

Existing regulations and development permitting procedures indicate that developmentrelated wetland loss may be slowed. Between 2004 and 2009, there were very few (<1%) estuarine 

emergent losses attributed to discrete anthropogenic actions that fill or otherwise convert salt marsh 

areas to uplands. This suggests that marine and estuarine vegetated wetlands (tidal salt marsh and 

shrubs) have been afforded protection by various State and Federal coastal regulatory measures 

(Dahl, 2011). Impacts are to some extent offset by coastal restoration programs. Examples of these 

programs are the Coastal Impact Assistance Program (CIAP), the Coastal Wetlands Planning, 

Protection, and Restoration Act (CWPPRA), and the Resources and Ecosystems Sustainability, 

Tourist Opportunities and Revived Economies of the Gulf Coast States Act (RESTORE Act) (refer to 

Chapter 3.3.2.8.4). Although development-related wetland loss may be slowed, cumulative impacts 

of past development and related infrastructure are expected to be moderate. 

Sea-Level Rise

There is increasing new evidence of the importance of the effect of sea-level rise (and marsh 

subsidence) as it relates to the loss of marsh or changes in marshes, marsh types, and plant 

diversity (Chapter 3.3.2.8.1; Spalding and Hester, 2007). Spalding and Hester (2007) show that the 

very structure of coastal vegetative communities would likely be altered by sea-level rise because 

community shifts would be governed by the responses of individual species to new environmental 

conditions. This could change the vegetative make up of different estuarine habitats and, in turn, 

could change faunal species presence.

Gulf Coast wetlands tend to occur at low elevations, often between 1 and 2 ft (0.3 and 0.6 m) 

above sea level. For example, if current projections are realized and sea level increases by 3.5 ft 

(1.1 m) in Galveston, Texas, by the year 2100 (USEPA, 2013b), most of Texas’ coastal wetlands 

would be under water well before 2100. A more conservative estimate of sea-level rise, known as 

the AR4 scenario, calls for an increase (globally) of 16 in (41 cm) by 2100 (NRC, 2010). Even this 

rate of increase would be likely to drown large areas of Gulf Coast wetlands, especially when local, 

relative sea-level rise is considered. Since 1870, global sea level has risen by about 8 in (20 cm) 

(USEPA, 2013b). Even at current measured rates of relative sea-level rise, vast areas of Gulf 

coastal wetlands can be expected to convert to open water as low-lying coastal marshes are 

inundated (refer to Chapter 3.3.2.8.1). Impacts to coastal habitats are expected to be major due to 

the large scale of wetland loss from sea-level rise.

Natural Processes

Along with increased human activities, hurricanes and tropical storms in the GOM have 

greatly impacted coastal habitats (Chapter 3.3.2.9). Intense storms can erode all of the vegetation 

and soil from some areas of marsh, leaving behind a body of water. An extreme example occurred 
Description of the Affected Environment and Impact Analysis 4-71

when hurricanes in 2005 resulted in land loss in Louisiana equivalent to approximately 42 percent of 

the projected total land loss over the next 50 years (Barras et al., 2003; Barras, 2006). These 

storms can also remove or bury submerged beds and the barriers that protect these beds from storm 

surges. This could weaken the existing populations of local submerged vegetation. Seagrass beds 

have been repeatedly damaged from hurricane overwash of barrier islands onto the beds. The 

presence of strong tropical storms is a routine background condition in the GOM that contributes to 

cumulative impacts to wetlands. Natural subsidence has caused wetland loss through compaction 

of Holocene strata (the rocks and deposits from 10,000 years ago to present). Stephens (2010) has 

identified faulting mechanisms in coastal Louisiana that actually may be causing what appears as 

subsidence. Refer to Chapter 3.3.2.8 for more information.

Whether it is from anthropogenic activities or a natural cycle, increased surface water temperature, 

sea levels, and storm events have impacts on seagrass beds by adding stress (e.g., burial, salinity 

changes, turbidity changes etc.) to this sensitive and already stressed ecosystem (Orth et al., 2006). 

Impacts to estuarine habitats are expected to be major because of the large scale of wetland loss 

from hurricanes and subsidence added to the ongoing stress these communities endure.

Mississippi River Hydromodification

With the construction of levees, dams, and other flood control structures along the 

Mississippi River, some of the natural processes that built the coastal Louisiana delta have been 

prevented, which has had serious impacts (Chapter 3.3.2.10). Beneficially, the hydromodification 

has allowed human settlement and development in coastal areas of Louisiana while also providing a 

stable navigation channel. However, by channelizing the river, it is prevented from flooding and 

distributing sediments that can build wetlands and counteract the effects of sea-level rise (Yuill et al., 

2009). When the Mississippi River floods, it brings nutrient-rich water and alluvial sediments to the 

wetlands. The water would provide nutrients for wetland vegetation, thereby encouraging plant 

growth. This growth can stabilize wetland sediments, which makes them less susceptible to erosion. 

The water also prevents the sediments from drying out and compacting due to loss of pore water 

and oxidation of organic material (Yuill et al., 2009). Sediment deposition in wetlands is vital for the 

area to stave off sea-level rise. Without new sediments coming into the marsh, a major contributor 

to vertical building processes is removed, and the wetlands become more at risk to being inundated 

by rising sea levels (Yuill et al., 2009). The hydromodification of the Mississippi River has 

exacerbated these issues by preventing the flooding of coastal wetlands in Louisiana, and as a 

result, those areas are experiencing some of the highest land-loss rates in the world; therefore, the 

impact has been major. While the cumulative impacts to coastal habitats from the factors described 

above range from negligible to major, the incremental impact to those habitats from a proposed 

lease sale would be negligible. The relatively small contribution of a proposed lease sale to OCS 

oil- and gas-related activity would have impacts that are much less than those attributed to several 

sources, as noted above.
4-72 Gulf of Mexico Multisale EIS

Incomplete or Unavailable Information

BOEM has identified incomplete or unavailable information regarding estuarine habitat. 

There is incomplete information about routine impacts, as the scenario forecast is only an estimate, 

and many global factors can affect OCS oil- and gas-related activity. There also remains 

unavailable information about the future rates of oil spills, as well as spill locations and volumes of 

oil.

There are unknowns regarding the future restoration efforts that are being planned, such as 

what projects would ultimately be constructed and how successful they may be. In addition, the 

future rates of relative sea-level rise are not known with certainty, and thus, resulting impacts to 

wetlands are unknown. Future rates of coastal development are unknown, as is the extent of 

impacts to estuarine systems thereof.

BOEM acknowledges that there remains incomplete or unavailable information that may be 

relevant to reasonably foreseeable significant impacts on estuarine systems. This incomplete or 

unavailable information includes potential data on the Deepwater Horizon, explosion, oil spill, and 

response that may be forthcoming. As there is substantial information available since the 

Deepwater Horizon explosion, oil spill, and response, which is included in this Multisale EIS, BOEM 

believes that the incomplete or unavailable information regarding the effects of the Deepwater 

Horizon explosion, oil spill, and response on estuarine systems would likely not be essential to a 

reasoned choice among alternatives. Regardless of the costs involved, it is not within BOEM’s 

ability to obtain this information from the NRDA process within the timeline contemplated in the 

NEPA analysis for this Multisale EIS. BOEM’s subject-matter experts have used what scientifically 

credible information is available in their analyses, and applied it using accepted scientific 

methodology. Compared with the historic and ongoing threats to wetlands, such as sea-level rise, 

natural factors such as hurricanes, and channelization, the remaining effects of the Deepwater 

Horizon explosion, oil spill, and response on wetlands are expected to be small.

BOEM has determined that the information is not essential to a reasoned choice among 

alternatives. Many studies have been produced that demonstrate the effects of exposure of wetland 

plants to crude oil, covering a wide range of exposure intensity, longevity, and oil characteristics. 

Much has been learned about the different survival and recovery rates of various plant species. In 

addition, studies have been produced regarding the long-term impacts of canal dredging and 

pipeline installation on wetlands. A proposed lease sale would result in a relatively minor addition to 

existing routine activities and accidental events, and therefore, the incremental contribution to 

wetland impacts from a proposed lease sale would be minor given what is currently known.

The potential for impacts from changes to the affected environment (post-Deepwater 

Horizon) and cumulative impacts remains whether or not the No Action or an action alternative is 

chosen, and therefore, the incremental contribution from a proposed action would be minor relative 

to cumulative impacts. BOEM used reasonably accepted scientific methodologies to extrapolate 

from existing information in completing this analysis and formulating the conclusions presented here.
Description of the Affected Environment and Impact Analysis 4-73

4.3.1.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

BOEM reviewed and analyzed the impacts to coastal habitats from routine OCS oil- and gasactivities, reasonably foreseeable accidental events, and the incremental contribution of a proposed 

action to the cumulative impacts to wetlands. It is expected that impacts from pipeline emplacement 

would be negligible with only 0-1 pipeline landfalls projected, and any impacts would be reduced or 

eliminated through mitigation (e.g., avoidance of impacts by use of modern techniques such as 

directional drilling). Although maintenance dredging of navigation channels and canals is expected 

to occur, a proposed action is expected to contribute only minimally to the need for this dredging. 

Secondary impacts to estuarine systems from a proposed action would result from OCS oil- and 

gas-related vessel traffic contributing to the erosion and widening of navigation channels and canals. 

Overall, the impacts to these habitats from routine activities associated with a proposed action are 

expected to be negligible due to the small length of projected onshore pipelines, the minimal 

contribution to the need for maintenance dredging, and the mitigating measures that would be used 

to further reduce these impacts.

The greater threat from an oil spill to coastal habitat is from a coastal spill as a result of a 

nearshore vessel accident or pipeline rupture. While a resulting slick may cause impacts to wetland 

habitat and surrounding seagrass communities, the equipment, vessel traffic, and personnel used to 

clean it up can also generate impacts to the area. Close monitoring and restrictions on the use of 

bottom-disturbing equipment would be needed to avoid or minimize those impacts. In addition, an 

assessment of the area covered, oil type, and plant composition of the wetland oiled should be made 

prior to choosing remediation treatment. Offshore oil spills resulting from a proposed action would 

have a low probability of contacting and damaging large areas of the coast, except in the case of a 

catastrophic event, which is not reasonably foreseeable and not expected to occur as a result of a 

proposed lease sale (Catastrophic Spill Event Analysis white paper, USDOI, BOEM, 2016c). This is 

because of the distance of the projected OCS oil- and gas-related activity to the coast, the likely 

weathered and therefore less toxic condition of oil (through evaporation, dilution, and 

biodegradation) should it reach the coast, and because wetlands are somewhat protected by barrier 

islands, peninsulas, sand spits, and currents. Overall, impacts to estuarine habitats from oil spills 

associated with activities related to a proposed action would be expected to be minor because of the 

distance of most of the resulting activities from the coast, expected weathering of spilled oil, 

projected low probability of large spills near the coast, resiliency of wetland vegetation, and 

availability cleanup techniques.

Cumulative impacts to wetlands are caused by a variety of factors, including the OCS oiland gas-related and non-OCS oil- and gas-related activities discussed above. Development 

pressures in the coastal regions of the GOM have been largely the result of tourism and residential 

beach side development, and this trend is expected to continue. The cumulative effects of human 

and natural activities in the coastal area have severely degraded the deltaic processes and have 

shifted the coastal area from a condition of net land building to one of net land loss. Deltaic 

Louisiana is expected to continue to experience the greatest loss of wetland habitat in the GOM. 

Wetland loss is also expected to continue in coastal Texas, Mississippi, Alabama, and Florida, but at 
4-74 Gulf of Mexico Multisale EIS

slower rates. A proposed action represents a small (>4.5%) portion of the cumulative OCS Program 

that would occur over the 50-year analysis period. Impacts associated with a proposed action are a 

minimal part of the overall OCS oil- and gas-related impacts. The incremental contribution of a 

proposed action to the cumulative impacts on coastal wetlands is expected to be minor. 

4.3.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of this alternative would be similar to those of Alternative A, except that there 

would be negligible impacts to coastal wetlands and submerged vegetation in Texas because no 

new OCS oil- and gas-related activity is forecasted in the WPA along the Texas coast with this 

alternative. Under Alternative B, the resulting OCS oil- and gas-related activity would be located off 

the coasts of Louisiana, Mississippi, and western Florida. The greater distance between these 

activities and the coastal habitats of Texas would reduce the impacts along the Texas coast, 

whether from routine activities or accidental events. Less use of service bases in Texas is likely, 

and the distance between oil spills associated with this alternative and the Texas coast is expected 

to be greater.

4.3.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

The impacts of this alternative would be less than those of Alternative A, as only a fraction of 

the resulting activity forecast for Alternative A is projected under Alternative C. For this alternative, 

there would be negligible impacts to coastal wetlands and submerged vegetation in Louisiana; 

negligible impacts to Mississippi, Alabama, and the panhandle of western Florida; and 

incrementally more impacts to the wetlands and submerged vegetation of Texas, compared with 

Alternative A. However, Alternative C would have less potential for impact than Alternative A or B as 

the level of projected OCS oil- and gas-related activities and impact-producing factors are much less 

in the WPA. For example, a range of 22-96 production wells are projected to be drilled and 

developed under Alternative C, whereas 46-671 production wells are projected to occur under 

Alternative B. The significance of impact-producing factors on estuarine habitats would be less for 

Alternative C as for Alternative A, as discussed in Chapter 2.2.2. 

4.3.1.2.4 Alternative D—Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, Live Bottom 

(Pinnacle Trend), and/or Blocks South of Baldwin County, Alabama Stipulations

The impacts of this alternative would be nearly identical to those of Alternative A because the 

available unleased blocks with topographic features do not contain wetlands or submerged 

vegetation and are too distant (over 25 km; 16 mi) from the coast to have indirect impacts either. In 

addition, there are only 367 blocks subject to the Topographic Features Stipulation, 74 blocks 

subject to the Live Bottom (Pinnacle Trend) Stipulation, and 32 blocks subject to the Blocks South of 

Baldwin County, Alabama Stipulation. This relatively small percentage of the total number of 
Description of the Affected Environment and Impact Analysis 4-75

The coastal barrier beaches 

and associated dunes are 

those beaches and dunes that 

line the coast of the northern 

Gulf of Mexico, including both 

barrier islands and beaches 

on the mainland.

unleased blocks would not be expected to generate a great contribution to OCS oil- and gas-related 

activity if leased.

4.3.1.2.5 Alternative E—No Action

If a proposed action does not occur, there would be no additional impacts to estuarine 

habitats; however, cumulative impacts would be the same as Alternative A. There could be some 

incremental increase in impacts caused by a compensatory increase in imported oil and gas to offset 

reduced OCS production, but it would likely be negligible. 

4.3.2 Coastal Barrier Beaches and Associated Dunes

In this chapter, BOEM reviewed and analyzed OCS 

oil- and gas-related routine activities and reasonably 

foreseeable accidental events. The approach of the analysis 

is to focus on the potential impact-producing factors from 

OCS oil- and gas-related routine activities (i.e., exploration, 

development, and production), as well as accidental events 

and cumulative impacts (Table 4-5). Routine activities 

associated with a proposed action that takes place on the 

OCS, where wells are drilled and platforms and pipelines are installed, would not impact the coastal 

barrier beaches, which are located from 3 to greater than 200 nmi (3.5 to 230.2 mi; 5.6 to 370.4 km) 

away. Other routine activities that support offshore oil and gas exploration, such as increased 

vessel traffic, maintenance dredging of navigation canals, pipeline installation, trash and debris, and 

construction of support infrastructure in the coastal areas, could potentially impact beaches and 

dunes. An analysis of the potential impacts from accidental events, primarily oil spills, associated 

with a proposed action is presented in this chapter, as is the incremental contribution of a proposed 

action to the cumulative impacts to beaches and dunes. Cumulative Impacts were analyzed for 

OCS oil- and gas-related activities and for other sources that could affect coastal barrier beaches 

and dunes (i.e., human impacts, storms, vessel traffic, subsidence, and sea-level rise).

Table 4-5. Coastal Barrier Beaches and Associated Dunes Impact-Producing Factors.

Coastal Barrier 

Beaches and 

Associated Dunes

Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Pipeline Construction 

and Maintenance Negligible Negligible Negligible Negligible None

Navigation Channel 

Maintenance 

Dredging

Negligible Negligible Negligible Negligible None

Vessel Operation 

(Support Use of 

Navigation Channels)

Negligible Negligible Negligible Negligible None
4-76 Gulf of Mexico Multisale EIS

Coastal Barrier 

Beaches and 

Associated Dunes

Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Disposal of OCSRelated Wastes Negligible Negligible Negligible Negligible None

Construction and Use 

of Coastal Support 

Infrastructure

Negligible Negligible Negligible Negligible None

Accidental Impacts

Oil Spills Minor Minor Minor Minor None

Cumulative Impacts

OCS Oil and Gas Moderate Moderate Moderate Moderate Moderate

Non-OCS Oil and 

Gas Major Major Major Major Major

Impact Significance Criteria

For this analysis, the following definitions were used to categorize impacts to coastal 

beaches and dunes:

• Negligible – Little to no measurable impacts in species composition and 

abundance and/or altering of beach profile or ecological function.

• Minor – Measureable but short-term and localized impacts to species 

composition and abundance and/or altering of beach profile or ecological 

function.

• Moderate – Damage to coastal habitats (impacts to species composition and 

abundance and/or altering of beach profile or ecological function) that is 

detectable, spatially extensive, but temporary and not severe. Can also be used 

to describe localized land loss.

• Major – Severe, bringing about detectable changes in species composition and 

abundance and/or altering of beach profile or ecological function well beyond that 

of normal variability. Changes would likely need to be both long-lasting and 

spatially extensive to have such an effect.

4.3.2.1 Description of the Affected Environment

Barrier beaches and associated dune habitats from Texas to the Florida panhandle may be 

impacted by activities resulting from a proposed action. These areas are comprised of the following 

geologic subareas:

• the barrier island complex of southern Texas;

• the Chenier Plain of eastern Texas and western Louisiana;
Description of the Affected Environment and Impact Analysis 4-77

• the Mississippi River Delta complex of southeastern Louisiana;

• the barrier-island and Pleistocene Plain complex of Mississippi and Alabama; 

and

• the Florida panhandle.

Barrier islands make up more than two-thirds of the northern GOM shore (Morton et al., 

2004a). These shorelines are usually sandy beaches that can be divided into several interrelated 

environments. Generally, beaches consist of a shoreface, foreshore, and backshore. The 

shoreface slopes downward and seaward from the low-tidal water line, under the water. The 

nonvegetated foreshore slopes up from the water to the beach berm-crest. The backshore is found 

between the beach berm-crest and the dunes, and may be sparsely vegetated. The dune zone of a 

barrier landform can consist of a single low dune ridge, several parallel dune ridges, or a number of 

curving dune lines that may be stabilized by vegetation. These elongated, narrow landforms are 

composed of wind-blown sand and other unconsolidated, predominantly coarse sediments.

Tropical storms and hurricanes are normal occurrences in the GOM and along the coast. 

The GOM has been hit extremely hard by very powerful hurricanes. These storms caused damage 

to barrier islands and beaches in all five of the Gulf Coast States. Beaches can recover naturally 

from the damage done by storms, but it may take many years (Houser et al., 2015). During storms, 

large waves can overwash lower coastal barriers, creating overwash fans or terraces behind and 

between the dunes. With time, opportunistic plants would reestablish on these flat, sand terraces, 

followed by the usual vegetative succession for this area. Along more stable barriers, where 

overwash is rare, the vegetative succession in areas behind the dunes is generally complete. 

Vegetation in these areas consists of scrubby woody vegetation, marshes, and forested wetlands. 

Saline and freshwater ponds may be found among the dunes and on the landward flats. These flats 

may grade into wetlands and intertidal mud flats that fringe the shore of lagoons, islands, and 

embayments. In areas where no bay or lagoon separates barrier landforms from the mainland, the 

barrier vegetation grades into scrub or forest habitat of the mainland.

Once formed, barrier islands are not static landforms; they are dynamic, with winds and 

waves constantly reworking and moving the barrier island sand, wherefore barrier landform 

configurations continually change, accreting and eroding, in response to these environmental 

conditions. Landform changes can be seasonal and cyclical, such as seen with the onshore 

movement of sand during the summer and offshore movement during the winter. Noncyclical 

changes in landforms can be progressive, causing barrier island movement. Barrier islands are also 

periodically reworked due to hurricanes and tropical storms.

Transgressive and regressive landforms are common across the GOM. A transgressive 

sequence moves the shore landward. Transgressive coastal landforms around the GOM have low 

profiles and are characterized by narrow widths; low, sparsely vegetated, and discontinuous dunes; 

and numerous, closely spaced, active washover channels. A regressive sequence moves the shore 
4-78 Gulf of Mexico Multisale EIS

seaward. Regressive barriers have high and broad dune profiles. These thick accumulations of 

sand may form parallel ridges.

Barrier islands, particularly vegetated ones with freshwater and or saltwater pools, may serve 

as habitat for a wide variety of animal life, especially birds (Chapter 4.8), including threatened and 

endangered species. The islands and spits protect the bays, lagoons, estuaries, salt marshes, 

seagrass beds, and other wetland environments, some of which may contain threatened or 

endangered species (Chapter 4.9). Barrier islands in the northern GOM extending from Atchafalaya 

Bay, Louisiana, to Mobile Bay, Alabama, are disintegrating rapidly as a result of combined physical 

processes involving sediment availability, sediment transport, and sea-level rise.

Oil from the Deepwater Horizon explosion and oil spill was documented by shoreline 

assessment teams to have stranded on approximately 560 mi (900 km) of CPA and EPA beach 

shoreline. Cleanup activities were conducted on 410 mi (660 km) of the affected beach. Two years 

after the spill, some oil remained on 427 mi (687 km) but at much lesser amounts (Michel et al., 

2013; OSAT-2, 2011). As beaches experienced erosion and deposition, oil would become buried, 

exposed, and remobilized multiple times, resulting in chronic re-oiling. Tropical Storm Lee (2011) 

and Hurricane Isaac (2012) caused extensive beach erosion and remobilization of oil residues. Oil 

residue mats were observed between the toe of the beach and the first offshore sand bar, providing 

another source of chronic sources of surface residue balls and surface residue patties (Michel et al., 

2013). Over time, more of the remaining oil has continued to be removed, while toxicity has 

decreased as the oil is further weathered. The buried supratidal samples underwent less 

biodegradation due to lack of oxygen, but they were estimated in 2011 to decrease to 20 percent of 

current levels within the next 5 years (OSAT-2, 2011).

As a result of the Deepwater Horizon explosion and oil spill, protective berms were 

constructed in Louisiana seaward of barrier islands to protect the inland marshes, wetlands, and 

seagrasses from incoming oil associated with this large spill. The berms were ineffective in stopping 

the oil, and none of the estimates of how much oil was collected on the berms was much more than 

1,000 bbl (National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, 2011). 

It took approximately 5 months to build roughly 12.5 mi (20.1 km) of berms at a cost of 

approximately $220 million. Long-term effects can include changes in hydrology and sediment 

transport along the coastal barrier islands, the loss of sand resources, and adverse impacts to 

benthic and pelagic organisms (Martinez et al., 2012). As a result, such berms are not likely to be 

approved as a response measure in the future.

Texas Barrier Island Complex

The barrier islands in Texas extend from the Mexican border to Galveston Bay. The GOM 

coastline of Texas is about 367 mi (590 km) long. The average rate of erosion of the Texas 

shoreline, from 1950 through 2012, was 2.3 ft (0.7 m) per year. While some of the coast has been 

gaining land, rates vary by location, with numerous locations experiencing rates of more than 11.5 ft 

(3.5 m) per year (State of Texas, General Land Office, 2015).
Description of the Affected Environment and Impact Analysis 4-79

The barrier islands are mostly accreted sediments that were reworked from river deposits, 

previously accreted Gulf shores, bay and lagoon sediments, and exposed seafloors (White et al.,

1986). The Texas coast has both low- and high-profile barriers. South Padre Island is an example 

of a low-profile barrier, with its narrow shape and discontinuous frontal dunes that are inundated by 

storm surges. Matagorda Island is an example of a high-profile barrier, which is typically wide with 

continuous, well-vegetated dune ridges (Morton et al., 2004a).

Padre Island National Seashore encompasses 70 mi (112 km) of coastline, making it the 

longest stretch of undeveloped barrier island in the world. It borders the Laguna Madre, a 

hypersaline lagoon, and it provides habitat for numerous plants and animals. It also serves as an 

important nesting ground for the endangered Kemp’s ridley sea turtles (Chapter 4.9.2).

Chenier Plain

The Chenier Plain of eastern Texas and western Louisiana began developing about 

2,800 years ago. During that period, Mississippi River Delta sediments were intermittently eroded, 

reworked, and carried into the Chenier Plain area by storms and coastal currents. This deposition 

gathered huge volumes of mud and sand, forming a shoreface that slopes very gently, almost 

imperceptibly, downward for a very long distance offshore. This shallow mud bottom is viscous and 

elastic, which generates hydrodynamic friction (Bea et al., 1983). Hence, wave energies along the 

barrier shorelines of the Chenier Plain are greatly reduced, causing minimal longshore sediment 

transport along the Chenier Plain (USDOI, GS, 1988). More recently, this shoreline has been 

eroding as sea level rises, converting most of this coast to transgressive shorelines.

The barrier beaches of the Chenier Plain are generally narrow, low, and sediment starved 

due to the nature of coastal currents and the shoreface. In some places, beach erosion has 

exposed relic marsh platforms that were buried by past overwash events, resulting in beaches 

composed of shelly sand, or discontinuous mud deposits among muddy sands.

Mississippi River Delta Complex

The Mississippi River Delta region comprises much of coastal Louisiana and adjacent 

Mississippi. It stretches from the Atchafalaya Bay to the Chandeleur Islands of Louisiana. Most 

barrier shorelines of the Mississippi River Delta are transgressive and trace the seaward remains of 

a series of five abandoned deltas. As a lobe of the Delta is abandoned by a shift in drainage, that 

portion begins to subside slowly into the sea and is further reduced by erosion. Some of the 

sediment may be reworked by wind and waves into barrier islands. The Chandeleur Islands and 

Grand Isle are examples of this. Gradually, woodland vegetation became established on the dune 

sands (e.g., oaks and oleander). Salty meadows, marshes, and lagoons occupy the lower terrain. 

The shorefaces of the Mississippi River Delta complex slope gently seaward, which reduces wave 

energies at the shorelines. Mud flats are exposed during very low tidal events. This slope is not as 

shallow as that found off the Chenier Plain.
4-80 Gulf of Mexico Multisale EIS

The barrier islands associated with the Mississippi River Delta are at the greatest risk for 

degradation from hurricanes and sand budget deficits; these include the Chandeleur-Breton Island, 

Timbalier Island, and Isle Dernieres chains in Louisiana. These chains of individual transgressive 

barrier island segments have progressively diminished in size while migrating landward (McBride 

et al., 1992). Most of southeastern Louisiana’s barrier beaches are composed of medium to coarse 

sand. Most dune zones of the Mississippi River Delta contain low, single-line dune ridges that may 

be sparsely to heavily vegetated.

Mississippi and Alabama Coasts

The Dog Keys define the Mississippi Sound of Mississippi and Alabama. The MississippiAlabama barrier islands have experienced increased rates of land loss since the mid-1800’s 

because of storms and sand budget deficits. The centers of most of the islands are migrating 

westward (Richmond, 1962; Otvos, 1979). These islands generally have high beach ridges and 

prominent sand dunes. They are well vegetated among and behind the dunes and around ponds.

Mississippi has about 33.9 mi (54.6 km) of barrier beaches (USDOI, FWS, 1999). The 

western district of the Gulf Islands National Seashore is located in Mississippi. Some of the habitats 

representative of coastal barrier and seagrass ecosystems are found on or behind Horn and Petit 

Bois Islands, which were designated as Wilderness Areas by Congress in 1978 through the 

establishment of the Gulf Islands Wilderness Area.

Dauphin Island, Alabama, represents about another 7 mi (11 km) of barrier beaches. The 

beaches are separated by wide passes with deep channels. Shoals (a place where a sea, river, or 

other body of water is shallow) are typically adjacent to these barriers. Unlike the other barrier 

islands, Dauphin Island is essentially a low-profile, transgressive barrier island, except for its eastern 

end. The western end is characterized by small dunes and many washover fans, exposed marsh 

deposits, and tree stumps exposed in the surf zone. The Gulf Shores region of Alabama extends 

from Mobile Point eastward to the Florida boundary, a distance of about 31 mi (50 km) (Smith, 

1984).

Florida Panhandle

The Florida panhandle has extensive beaches with multiple habitats, including sandy 

mainland beaches, broad peninsulas, and narrow barrier islands. Two long, narrow barrier islands 

(Santa Rosa Island and Perdido Key) form the Gulf shore west of Destin and are part of the Gulf 

Islands National Seashore (Figure 4-24 in Chapter 4.12.1). Both can be reached by road and 

experience tourism in the form of camping, picnicking, swimming, bird watching, and fishing.

Coastal land loss from shoreline change in the Florida panhandle is associated with erosion 

of sandy beaches and barrier islands, especially around inlets, while bays and lagoons tend to 

experience lower loss rates because the waterbodies are generally small or protected by erosion 

control structures (Morton et al., 2004a). The average long-term erosion rate, from the 1800’s 

through 2001, was estimated as -2.6 ft/yr (-0.8 m/yr), which is lower than the other Gulf Coast 
Description of the Affected Environment and Impact Analysis 4-81

States. This can be attributed to relatively low wave energy and frequent beach nourishment 

(Morton et al., 2004a).

These barrier beaches and dune habitats also play an important role to ESA-listed species; 

BOEM consults on these species with the FWS. These species include sea turtles, beach mice, and 

birds; to read about the protected species that use these habitats, refer to Chapters 4.9.2, 4.9.3, 

and 4.9.4, respectively.

4.3.2.2 Environmental Consequences

Routine Activities

This chapter considers impacts from routine activities associated with a proposed action to 

the physical shape and structure of barrier beaches and associated dunes. The primary impactproducing factors from routine activities associated with a proposed action that could affect these 

environments include pipeline emplacements, vessel traffic (navigation channel use) and dredging, 

trash and debris, and infrastructure construction.

Pipeline Emplacements

Many existing OCS Program-related pipelines made landfall on barrier islands and 

shorelines (Chapter 3.1.3.3). Pipeline landfall sites on barrier islands could potentially cause 

accelerated beach erosion and island breaching. This occurs when pipeline canals are dug through 

beaches, and then widen over time. A proposed action is not expected to include new pipelines that 

make landfall on barrier islands or mainland beaches (0-1 new pipeline landfalls are projected). 

Modern pipeline construction typically employs horizontal, directional (trenchless) drilling techniques 

and open-water routes to the extent possible to avoid damages to estuarine systems and beaches. 

Similar features are now commonly required to minimize any impacts from pipeline landfalls. 

Studies have shown that little to no impact to barrier beaches results from techniques like directional 

pipeline emplacement (LeBlanc, 1985; Wicker et al., 1989). Federal and State regulatory programs 

and permitting processes encourage the use of directional boring technology to reduce and perhaps 

eliminate impacts to barrier beaches or dunes. Because of the regulations and new construction 

methods, and the limited projection for, at most, one new pipeline landfall, the effects on barrier 

beaches and dunes from pipeline laying activities associated with a proposed lease sale are 

expected to be negligible.

Vessel Traffic and Dredging

Vessel traffic that may support a proposed action and navigation channels projected to be 

used in support of a proposed action are discussed in Chapter 3.1.7.6 and are shown in Table 3-6. 

As a result of a proposed action, it is not expected that the number of OCS oil- and gas-related 

navigation channels would change. Waves generated by boats, ships, barges, and other vessels 

erode unprotected shorelines and accelerate erosion in coastal barrier beaches already affected by 

natural erosion processes. Only a limited reach of the navigation channels cross the shoreline 

adjacent to beaches or dunes, and these reaches are generally armored with rock. The existing 
4-82 Gulf of Mexico Multisale EIS

armored navigation channels minimize or eliminate the potential for shoreline erosion from vessel 

traffic.

A proposed action is estimated to account for <2 percent of the service-vessel traffic in 

navigation canals associated with the OCS Program from 2017 through 2066 (Chapter 3.1.7.6; 

Tables 3-2 and 3-6). Erosion of coastal barrier beaches and associated dunes from vessel traffic 

resulting from a proposed action are expected to be negligible because of the small percentage of 

total vessel traffic related to the OCS Program and the armoring of the channels most highly used for 

OCS oil- and gas-related activities.

Periodic maintenance dredging is expected in existing navigation channels through barrier 

passes and associated bar channels. Maintenance dredging of barrier inlets and bar channels 

removes sediment from the system, contributing to beach erosion. Materials from maintenance 

dredging of bar and pass channels are typically discharged to nearby ocean dumping sites in the 

GOM (Chapter 3.3.2.4.6) or they are used for marsh creation or beach nourishment projects as part 

of mitigation (Morton, 2008). Jetties or bar channels serve as sediment sinks by intercepting 

sediment in longshore littoral drift (the movement of sediment along the shoreline by currents). 

Negative effects of sediment sinks created by jetties can be mitigated by filling the downdrift side of 

the jetty with appropriate sediment. These dredging activities are permitted, regulated, and 

coordinated by the COE with the appropriate State and Federal resource agencies. Effects from 

maintenance dredging related to a proposed action on coastal barrier beaches and associated 

dunes are expected to be minor due to the small contribution from a proposed action to total 

channel use and the offsetting effects of beach nourishment.

Trash and Debris

Trash and debris (Chapters 3.1.3.5 and 3.3.2.4.8) can be an issue for coastal habitats, 

including beaches and dunes and the fauna that reside in these habitats. Fauna that utilize barrier 

beaches and dunes could ingest or become entangled in trash and debris. This can have lethal 

impacts like suffocation or sublethal impacts like loss of a limb. The BSEE provides information on 

marine debris and awareness and requires training of all OCS personnel through NTL 2015-

BSEE-G03, which also informs operators of regulations set forth by other regulatory agencies (i.e., 

the USEPA, USCG, and others; refer to Chapter 4.12). Due to the annual awareness training 

required by marine debris mitigations, the handling of waste and trash by industry has improved 

greatly and the effects on coastal habitats are minimized. Because lease stipulations and 

regulations, as clarified by NTLs, are in place to reduce impacts from marine trash and debris, 

impacts related to marine trash and debris would result in negligible impacts to coastal barrier 

beaches and associated dunes.

Coastal Infrastructure Construction 

Projected new facilities that are attributed to the OCS Program and a proposed action would 

rarely, if ever, be located on coastal barrier beaches (Chapter 3.1.7). There are 0-1 gas processing 

plants projected to be constructed as a result of a proposed action. Existing inland facilities may, 
Description of the Affected Environment and Impact Analysis 4-83

through natural erosion and shoreline recession, be located in the barrier beach and dune zone and 

contribute to erosion there. A proposed action may extend the life and presence of facilities in 

eroding areas, which could accelerate localized erosion; however, the impacts on coastal barrier 

beaches and associated dunes in the vicinity of the construction of a gas processing plant from a 

proposed action are expected to be negligible or none, as the location of such a facility is not likely 

to be adjacent to beaches.

Accidental Events

The types and sources of spills that may be reasonably foreseeable from a proposed lease 

sale and their characteristics are described in Chapter 3.2. There is also a risk analysis of 

accidental events in Chapter 3.2.1. A low-probability catastrophic spill is discussed in the 

Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2016c).

The only accidental event associated with a proposed action likely to impact beaches would 

be a spill and the associated cleanup activities. Impacts to biological, recreational, and 

archaeological resources associated with beach and dune environments are described in the impact 

analysis chapters for those specific resources (Chapters 4.9, Protected Species; 4.12, Recreational 

Resources; and 4.13, Archaeological Resources).

Effects of Oil on Beaches

The effects from coastal oil spills depend on the geographic location, volume, and rate of the 

spill, type of oil, oil-slick characteristics, oceanic conditions, season at the time of the spill, and 

response and cleanup efforts (Chapter 3.2.7). The resiliency of coastal beaches and the impact of 

oil on these beaches are, in part, based on the toxicity of the oil’s components once it reaches the 

beaches. Microbial biodegradation can reduce the toxicity of crude oil by decreasing PAH 

concentrations. However, submerged oil mats found in GOM waters adjacent to beaches can resist 

weathering and may serve as long-term sources of remnant oil and PAHs to beach ecosystems 

(Hayworth et al., 2011; Elango et al., 2014). In addition, buried supratidal samples undergo less 

biodegradation due to a lack of oxygen (OSAT-2, 2011).

If unweathered oil reached the beaches, the associated interstitial microfauna would be 

affected in several ways, including community shifts, toxic effects, and the physical disturbance of 

response efforts. A shift in the microbial community would tend to increase dominance by 

hydrocarbon degraders (Kostka et al., 2011). This shift can occur within days of contamination with 

crude oil, stimulating the breakdown of the contaminants present in the oil (Horel et al., 2012). Toxic 

constituents of the oil can have both lethal and sublethal impacts to resident plants and fauna. 

Equipment and personnel used in cleanup efforts can generate the greatest direct impacts to an 

area, such as the removal of sand from the beaches, disturbance of beach and foredune sands 

through foot traffic, mechanized cleanup equipment (e.g., sifters), dispersal of oil deeper into sands 

and sediments, and foot traffic in marshes impacting the distribution of oils and marsh vegetation.
4-84 Gulf of Mexico Multisale EIS

Coastal Spills

Coastal spills from damage to pipelines, vessel collisions, and malfunctions of onshore 

production or storage facilities have the greatest potential for affecting the coastal barrier beaches 

due to their proximity to the resources. Because very little OCS oil- and gas-related activity takes 

place on beaches, inland spills that occur in the vicinity of GOM tidal inlets present a greater 

potential risk to barrier beaches and dunes because the inlets can provide a path for oil to reach the 

beaches.

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 energy-related, other 

commercial, and recreational activities remains the same. BOEM’s analysis shows that 96 percent 

of spills from OCS oil-and gas-related activity are <1 bbl, with an average size of <0.05 bbl 

(Anderson et al., 2012). Table 3-13 shows that there was only one spill ≥1,000 bbl in the coastal 

waters from Texas through Alabama during the period 2002-2014. Because of the small contribution 

to all such spills from the proposed action, the small size of most spills, the percentage of spilled oil 

volume that would likely reach coastal barrier beaches, and the breakdown of contaminants by 

microbial communities, impacts of coastal spills to barrier beaches and dunes are expected to be 

minor. 

Offshore Spills

There are various factors and conditions that affect the toxicity and severity of the impacts of 

oil spills on the barrier island systems, dunes, and the associated vegetation. For an offshore spill 

<1,000 bbl to make landfall, the spill would have to occur proximate to State waters (defined as 

3-12 mi [5 19 km] from shore). If a spill were to occur proximate to State waters, only a spill >50 bbl 

would be expected to have a chance of persisting long enough to reach land. Spills ≥50 and 

<1,000 bbl are very infrequent (Chapter 3.2.1.6.4). If an oil spill contacted the shoreline, the 

intertidal area and the beach face would likely be contacted. For the oil to contact the dunes, 

extreme high tides would be needed to carry oil from a spill across and onto the dunes.

Two important variables during an oil spill for impacts on beaches and dunes involve location 

(distance of spill from landfall) and weather. For example, if there is sufficient distance and 

favorable weather conditions between the spill and landfall, the oil can be dispersed, thinned, and 

emulsified. This would allow for conditions supportive of biodegradation, volatilization, and 

photooxidation to break down the oil. Most spills from the OCS are likely to be distant enough that, 

should a slick from such a spill make landfall, the volume of oil remaining in the slick is expected to 

be small. Due to the distance of the spill from shore, the weather, the time oil remains offshore, and 

dispersant use (Chapter 3.2.7.2.2), OCS crude oil would be less toxic when it reaches the coastal 

environments. For example, after the Deepwater Horizon explosion and oil spill, the majority of oil 

deposits on GOM beaches were highly weathered and samples showed 86-98 percent depletion of 

total polycyclic aromatic hydrocarbons (PAHs) (OSAT-2, 2011). However, should spills from the 

OCS occur proximate to State waters, they could reach shore before much weathering, evaporation, 

or dispersal had occurred.
Description of the Affected Environment and Impact Analysis 4-85

The probabilities of an offshore spill ≥1,000 bbl occurring and contacting environmental 

features are described in Chapter 3.2.1.5.8. The probabilities of oil spills ≥1,000 bbl occurring and 

contacting State waters can be found in Figure E-20. The highest probability as a result of a 

proposed action is estimated at 26 percent for the State waters of both Texas and West Louisiana. 

Should spills from the OCS occur proximate to State waters, they could reach shore before much 

weathering, evaporation, or dispersal had occurred. However, because the majority of spills 

estimated to occur are relatively small (>99% estimated to be <50 bbl), the distance from coastal 

communities, improved technologies, and the dynamic nature of the coastal environment, offshore 

spills are expected to have a minor impact on the estuarine community.

Cumulative Impacts

This cumulative analysis considers the effects of impact-producing factors related to a 

proposed action, prior and future OCS lease sales in the Gulf of Mexico, State oil and gas activities, 

other governmental and private projects and activities, and pertinent natural processes that may 

affect barrier beaches and dunes.

OCS Oil- and Gas-Related Impacts

Pipeline Emplacements, Vessel Traffic (Navigation Channel Use), Dredging, Trash and 

Debris, and Infrastructure Construction

Continued navigation channel use and dredging support of a proposed action could impact 

coastal habitats. Maintenance dredging of barrier inlets and bar channels is expected to continue, 

which removes sediment from the system, contributing to beach erosion. Mitigation of impacts 

involves strategically placing dredged sediment where adjacent barrier-island shores would receive it 

for island nourishment and rebuilding (Morton, 2008). Beneficial uses of dredged material include 

beach nourishment for the more sandy materials, and much of the impacts from dredging are 

expected to be mitigated through the beneficial use program implemented by the COE. Further 

discussion of the beneficial use of dredged material can be found in Chapter 3.3.2.9.5. Impacts to 

beaches from maintenance dredging would occur regardless if a proposed action is implemented or 

not. Less than 27 percent of traffic using navigation channels in the GOM is expected to be related 

to the cumulative OCS Program (Tables 3-23 and 3-6). A proposed action is estimated to account 

for less than 2 percent of the service-vessel traffic in the OCS. Impacts to beaches from 

maintenance dredging related to OCS oil and gas are expected to be minor. Impacts to beaches 

from OCS oil- and gas-related marine debris would be minor to negligible. 

The effects to coastal barrier beaches and associated dunes from pipeline emplacements 

and the construction or continued use of infrastructure in support of a proposed action are expected 

to be restricted to temporary and localized disturbances. Existing pipelines were placed using older 

techniques and have caused and would continue to cause barrier beaches to narrow and breach. 

Pipeline landfalls projected in support of the cumulative OCS scenario are expected to cause 

negligible impacts to barrier beaches because of the use of modern, nonintrusive installation 

methods.
4-86 Gulf of Mexico Multisale EIS

Oil Spills

Due to the proximity of coastal spills to barrier islands and beaches, such spills pose a threat 

to coastal barrier beaches and dunes. As noted in Table 3-13, a few coastal spills ≥1,000 bbl have 

been recorded in the coastal waters from Texas through Alabama during the period 2002-2014. 

Spills that occur in or near the Chandeleur or Mississippi Sounds could affect the coastal barrier 

beaches and dunes in the Gulf Islands National Seashore and the Breton National Wildlife Refuge.

Oil from most offshore spills, except perhaps from OCS oil- and gas-related activities close to 

the boundary with State waters, is expected to be weathered and normally treated offshore. 

Therefore, most of the toxic components would have dissipated by the time it contacts coastal 

beaches. The cleanup impacts of these spills could result in a short-term (up to 2 years) adjustment 

in beach profiles and configurations as a result of sand removal and disturbance during the cleanup 

operations. Cleanup efforts would be monitored in an effort to ensure the least amount of 

disturbance to the areas. However, spill data from the OCS shows that, over decades of activity, 

tens of thousands of barrels of oil have been spilled (Chapter 3.2.1.1.3). Impacts from OCS oil- and 

gas-related oil spills are expected to be moderate due to distance, weathering, and the estimated 

small number of large OCS spills that would make landfall.

Oil from the Deepwater Horizon explosion and oil spill was documented by shoreline 

assessment teams to have stranded on approximately 560 mi (900 km) of CPA and EPA beach 

shoreline. Cleanup activities were conducted on 410 mi (660 km) of the affected beach. Two years 

after the spill, some oil remained on 427 mi (687 km) of the beach but at much lesser amounts 

(Michel et al., 2013; OSAT-2, 2011). As beaches experience erosion and deposition, oil would 

become buried, exposed, and remobilized multiple times, resulting in chronic re-oiling. Tropical 

Storm Lee (2011) and Hurricane Isaac (2012) caused extensive beach erosion and remobilization of 

oil residues. Oil residue mats were observed between the toe of the beach and the first offshore 

sand bar, providing another source of chronic sources of surface residue balls and surface residue 

patties (Michel et al., 2013). Over time, more of the remaining oil has continued to be removed, 

while toxicity has decreased as the oil is further weathered. The buried supratidal samples 

underwent less biodegradation due to lack of oxygen, but they were estimated to decrease to 

20 percent of current levels within 5 years (OSAT-2, 2011). Accidental spills as a result of a lowprobability catastrophic event are discussed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2016c).

Non-OCS Oil- and Gas-Related Impacts

Vessel Traffic (Navigation Channel Use)

Construction of the existing navigation channels has replaced beaches with the waterways in 

some cases, while other channels were constructed using existing passes (Chapter 3.3.2.8.5). 

Construction of the channels involves removal of sand that is no longer available for longshore drift 

to adjacent beaches. Maintenance dredging of barrier inlets and bar channels would continue to 

remove sediment from the system, contributing to beach erosion. Sand is removed during dredging, 
Description of the Affected Environment and Impact Analysis 4-87

and only a fraction of this sand is used for beach nourishment. Disposal of dredged material outside 

of the littoral zone represents a net loss of sand to the system, and thus, maintenance dredging has 

contributed to net deficits (Byrnes et al., 2012). These impacts would occur from necessary channel 

maintenance to accommodate all vessel traffic, resulting in moderate impacts to beaches. More 

than 98 percent of total vessel traffic is not associated with a proposed action, and therefore, the 

incremental impacts associated with a proposed action are expected to be negligible. 

Oil Spills

Non-OCS oil- and gas-related oil spills can occur as a result of import tankers, barge, or 

shuttle tanker accidents during transit or offloading, State-related oil production activities, and 

various kinds of petroleum product transfer accidents. State-related oil production activities are 

concentrated in coastal areas, where spills could potentially cause greater impacts to beaches. The 

impacts of non-OCS oil- and gas-related spills are expected to be moderate. 

The GOM has more natural oil seeps (providing ~980,000 bbl/year; refer to Chapter 

3.3.2.15.2) than any other marine environment in North America; therefore, it has a resident 

population of microbiota, including oil-biodegrading bacteria, that degrades additional oil that enters 

the environment (Atlas and Hazen, 2011). This resident microbial population increases the 

resiliency of beaches to oil spill impacts.

River Hydromodification and Beach Protection

Over the course of geological history, the barrier islands have migrated toward the present 

coast. The Gulf-facing coasts of the barrier islands have been eroded by the steady relative rise in 

sea level. Human disturbance has hastened the erosion of barrier beaches and dunes. Channel 

deepening and widening along the Mississippi River and other major coastal rivers, in combination 

with channel training and bank stabilization work, has resulted in the reduced delivery of sediment to 

the eroding deltas along the mouths of the rivers and to the offshore barrier islands. This, coupled 

with beach building and stabilization projects utilizing mined sands, jetties, groins, and other means 

of sediment capture, is depriving natural restoration of the barrier beaches through sediment 

nourishment and sediment transport.

Subsidence, erosion, and dredging of inland coastal areas with the concurrent expansion of 

tidal influences continually increase tidal prisms around the GOM. These changes may result in the 

opening and deepening of many new tidal channels that connect to the GOM and inland 

waterbodies. Due to the increased flow, these incremental changes would cause adverse impacts to 

barrier beaches and dunes. Efforts to stabilize the GOM shoreline have adversely impacted barrier 

landscapes. Large numbers and varieties of stabilization techniques for navigation channels have 

been applied along the Gulf Coast. These efforts have contributed to coastal erosion by depriving 

downdrift beaches of sediments, which accelerates erosion there, and by increasing or redirecting 

the erosional energy of waves (Morton, 1982). Over the last 20 years, dune and beach stabilization 

have been better accomplished by using more natural applications such as sand dunes, beach 

nourishment, and vegetative plantings. Impacts of river channelization and beach protection are 
4-88 Gulf of Mexico Multisale EIS

expected to be moderate because of the disruption of sediment nourishment and sediment 

transport.

Other Anthropogenic and Natural Processes

Barrier beaches along the Gulf Coastal have experienced erosion and landward retreat 

(marine transgression) because of natural processes enhanced by human activities (Chapter 

3.3.2.). Adverse effects on barrier beaches and dunes have resulted from changes to the natural 

dynamics of water and sediment flow along the coast. This can happen in an attempt to control 

catastrophic floods and change the natural environment to better accommodate navigation on 

waterways used to support OCS oil- and gas-related and non-OCS oil- and gas-related vessel traffic. 

Rising sea levels are expected to continue to inundate or fragment low-lying coastal areas, including 

sandy beaches and barrier islands (Dahl, 2011). Sea-level rise and coastal subsidence and tropical 

storms exacerbate and accelerate the erosion of coastal barrier beaches along the Gulf Coast. The 

Gulf Coast and the associated barrier islands and dunes have been impacted by high-intensity 

hurricanes and tropical storms over the past millenia, resulting in natural changes in barrier island 

topography and decreases in beach elevation (USDOI, GS, 2008; Barras, 2007a). Due to the more 

gentle slopes, removal of beach ridges, and cuts into the mainland barrier beaches, the remnant 

transition zone between the water and the current beach ridge may be more vulnerable to spills. 

Historically, recovery of beaches to their pre-storm state ranges from years to decades (Houser 

et al., 2015).

If the topography is modified, it may result in hydrological changes that enable further

sediment transport from the islands. This provides pathways for further erosion and saltwater 

intrusion into the less salt-tolerant interior vegetated habitats of the islands. The loss of elevation, 

combined with the shoreline retreat and removal of vegetation further aggravated by the hurricanes, 

allows for the expansion of the overwash zone. This lessens the pre-storm protection of the coast 

provided by these barrier islands. The reduction in island elevation results in less frontline protection 

to valuable marshes and puts urban and industrial areas protected by these marshes at a higher risk 

(USDOC, NMFS, 2007b).

Hurricanes and tropical storms would remain a part of the Gulf Coast weather pattern and 

would continue to affect the elevations of barrier islands, mainland beaches, and dunes. Depending 

on storm frequency and intensity, it may be possible for coastal restoration and protection projects to 

mitigate some of the physical damage to these areas.

Gulf Coast barrier beaches tend to occur at low elevations, between sea level and several 

feet above sea level. Beach erosion due to sea-level rise has increased along certain shorelines 

(Dahl, 2011). If current projections are realized and the sea level increases by 3.5 ft (1.1 m) in 

Galveston, Texas, by 2100 (USEPA, 2013), much of Texas’ coastal beaches would be under water 

well before 2100. A more conservative estimate of sea-level rise, known as the AR4 scenario, calls 

for an increase (globally) of 16 in (41 cm) by 2100 (NRC, 2010). Even this rate of increase would be 

likely to impact Gulf Coast beaches, especially when local, relative sea-level rise is considered. 
Description of the Affected Environment and Impact Analysis 4-89

Since 1870, global sea level has risen by about 8 in (20 cm) (USEPA, 2013d). Even at current 

measured rates of relative sea-level rise, large areas of GOM coastal beaches can be expected to 

be inundated (refer to Chapter 3.3.2.12.1). Impacts to coastal habitats are expected to be major

due to the large scale of inundation from sea-level rise and the erosion due to hurricanes and human 

activities.

Recreational Use, Tourism, and Development

Recreational use of beaches is discussed in Chapter 4.12 (Recreational Resources). 

Recreational use of barrier beaches and dunes can have impacts on the stability of the landform. 

Vehicle and pedestrian traffic on sand dunes can stress and reduce the density of vegetation that 

binds the sediment and stabilizes the dune. Destabilized dunes are more easily eroded by winds, 

waves, and traffic. Recreational vehicles and even hikers have caused impacts where road access 

is available and the beach is wide enough to support vehicle use. Most barrier beaches in Texas are 

accessible to people for encouraged recreational use because of public road access. It also 

provides for public acquisition of private beachfront property. Most barrier beaches in Louisiana are 

relatively inaccessible for regular recreational use because they are in coastal areas with limited 

road access. Mississippi has coastal beaches behind the barrier islands that are accessible for 

recreational use, and the barrier islands experience extensive recreational use by boaters. Most 

barrier beaches in Alabama and the panhandle of Florida are accessible to foot traffic through road 

access, and their use is encouraged. There would continue to be seaside real-estate development 

where road access is available. The protection of dunes, beaches, and coastal environments are 

regulated through the Coastal Management Programs of the states, as well as the COE’s permitting 

program. This helps to assure that projects are constructed consistent with the Federal CZMA 

guidelines in order to preserve the integrity of the coastal ecosystem. In the years 2004 through 

2009, there were modest gains in marine and estuarine nonvegetated wetlands, a category that 

includes beaches (Dahl, 2011; Dahl and Stedman, 2013). A proposed action would not provide any 

additional access that would result in increased negative cumulative impact to the barrier beaches 

and dunes.

Development along the Gulf Coast has impacted coastal barrier beaches. Census data 

show that coastal areas are experiencing much higher growth than noncoastal areas. However, 

census data may underestimate this trend due to undercounting of seasonal residents. 

Infrastructure needed to support seasonal influxes of people can impact coastal barrier beaches 

(Dahl and Stedman, 2013). Hotels, restaurants, stores, and bars have been built on or adjacent to 

many coastal beaches, resulting in loss of habitat as well as the introduction of wastewater into 

coastal waters. High-use “amenity” beaches can benefit from frequent beach nourishment projects 

that supply large quantities of sand. Impacts are to some extent offset by coastal restoration 

programs. Examples of these programs are the Coastal Impact Assistance Program (CIAP), the 

Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA), and the RESTORE Act 

(refer to Chapter 3.3.2.12.4). Due to the protection from development of beaches included in the 

Gulf Islands National Seashore, restrictions on development by the various regulatory programs and 
4-90 Gulf of Mexico Multisale EIS

continuing cumulative impacts of past development on coastal barrier beaches, impacts are 

expected to be moderate. 

Coastal barrier beaches have experienced severe adverse cumulative impacts from human 

activities and natural processes. Human activities that have caused the greatest adverse impacts 

are navigation channel stabilization and maintenance, beach stabilization structures, oil spills, 

recreation and development, river channelization and damming, and pipeline canals. Most barrier 

beaches in Texas, Alabama, and Florida are accessible to people for recreational use, and their use 

is encouraged and intense. Excessive recreational use can result in damage to dunes, resulting 

from the loss of dune stabilizing plants. Existing pipelines were placed using older techniques and 

have caused and may continue to cause barrier beaches to narrow and breach. Natural and 

anthropogenic events have combined to cause erosion of barrier and shoreline landforms along the 

Gulf Coast. Cumulative impacts to barrier beaches and dunes from these sources are considered to 

be major. 

While the cumulative impacts to coastal barrier beaches from the factors described above 

range from negligible to major, the incremental impact to beaches from a proposed lease sale would 

be negligible. The relatively small contribution of a proposed lease sale to OCS oil- and gas-related 

activity would have impacts that are much less than those attributed to several sources, as noted 

above.

Incomplete or Unavailable Information

BOEM acknowledges that there remains incomplete or unavailable information regarding 

coastal barrier beaches and associated dunes in the GOM. There is incomplete information about 

routine impacts, as the scenario forecast is only an estimate, and many global factors can affect 

OCS oil- and gas-related activity. There also remains unavailable information about future rates of 

oil spills, as well as the locations and volumes of oil. Future rates of coastal development are 

unknown, as is the extent of such impacts to coastal barrier beaches. There are also unknowns 

regarding the future restoration efforts being planned, such as what specific projects would ultimately 

be constructed and how successful they may be. In addition, the future rates of relative sea-level 

rise are not known with certainty (Hausfather, 2013), and thus, the resulting impacts to coastal 

barrier beaches and associated dunes are unknown.

A large body of information regarding impacts of the Deepwater Horizon explosion, oil spill, 

and response upon coastal barrier beaches and associated dunes has been developed and 

continues to be developed through the NRDA process, but information remains incomplete. As 

there is substantial information available since the Deepwater Horizon explosion, oil spill, and 

response, which has been analyzed for this Multisale EIS, BOEM believes that the incomplete or 

unavailable information regarding the effects of the Deepwater Horizon explosion, oil spill, and 

response on coastal barrier beaches and dunes would likely not be essential to a reasoned choice 

among alternatives. The incomplete information would not be available within the timeframe 
Description of the Affected Environment and Impact Analysis 4-91

contemplated by the NEPA analysis of this Multisale EIS. However, much is known about the extent 

of the oiling of beaches and the continuing degradation of the remaining oil.

BOEM has determined that the information is not essential to a reasoned choice among 

alternatives. BOEM’s subject-matter experts have used what scientifically credible information is 

available in their analyses, applied using accepted scientific methodology. Many studies have been 

produced that demonstrate the effects of exposure of beaches to crude oil, covering a wide range of 

exposure intensity, longevity, and oil characteristics. Much has been learned about the effect of oilspill cleanup on beaches and the degradation rates of oil over time. In addition, studies have been

produced regarding the long-term impacts of navigation canal dredging on beaches and barrier 

islands. A proposed lease sale would result in a relatively minor addition to existing routine activities 

and accidental events, and therefore, the incremental increase in impacts to coastal barrier beaches 

and dunes from a proposed lease sale would be minor given what is currently known.

The potential for impacts from changes to the affected environment (post-Deepwater 

Horizon) and cumulative impacts remains whether or not the No Action or an action alternative is 

chosen. Compared with the historic and ongoing threats to coastal barrier beaches and dunes, such 

as sea-level rise, development threats, and sediment deficits, the remaining effects of the Deepwater 

Horizon explosion, oil spill, and response on coastal barrier beaches and dunes is expected to be 

small.

4.3.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Impacts from most routine activities related to a proposed action would be expected to be 

negligible since most routine activities are located far from coastal beaches. Impacts to coastal 

barrier beaches and associated dunes from pipeline emplacements, navigation channel use and 

maintenance dredging, and construction or continued use of infrastructure in support of a proposed 

action are expected to be restricted to temporary and localized disturbances and to cause negligible

impacts to barrier beaches because of the small number of expected pipeline landfalls and the small 

contribution from a proposed action to channel use and maintenance. Any new OCS oil- and gasrelated infrastructure would not be expected to be constructed on barrier beaches. Indirect impacts 

from routine activities, such as disruption of sediment transport by maintenance dredging of 

channels or erosion resulting from pipeline emplacements, are negligible. 

Minor and localized impacts to the physical shape and structure of barrier beaches and 

associated dunes may be expected to occur as a result of accidental events, such as oil spills, 

associated with a proposed action. Such impacts could be a result of cleanup efforts in addition to 

the spill itself. Should a spill contact a barrier beach, sand removal during cleanup activities would 

likely be minimized because current spill-response activities discourage physical cleanup methods 

that impact beach profiles. The Net Environmental Benefits Analysis done as part of the OSAT-2 

report (2011) noted that the environmental impacts of residual oil remaining after cleanup are 

relatively small when compared with the impacts of continued cleanup efforts on both beach habitats 

and associated resources.
4-92 Gulf of Mexico Multisale EIS

The impacts of oil spills and related cleanup efforts from both OCS oil- and gas-related and 

non-OCS oil- and gas-related sources to the Gulf Coast depend on the size, frequency, distribution, 

locations, and collective spatial and temporal features of the spills. Impacts would include stranding 

of surface residue balls and patties, and submerged tar mats may persist in adjacent waters, 

representing a chronic source of contamination, particularly after storms. Changes to beach 

topography could result from cleanup efforts. Overall impacts from oil spills are expected to be 

minor, with the exception of a catastrophic event, which is not considered reasonably foreseeable 

and is not part of a proposed action or likely expected to occur. Impacts as a result of a lowprobability catastrophic event are discussed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2016c).

Compared with other impact-producing factors on coastal barrier beaches and dunes, the 

incremental contribution of a proposed action to the cumulative impacts to these resources is 

expected to be minor. 

4.3.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of this alternative would be similar to those of Alternative A, except that there 

would be negligible impacts to coastal barrier beaches and dunes in Texas because no OCS oiland gas-related activity is forecast in the WPA along the Texas coast with this alternative. Under 

Alternative B, the resulting OCS oil- and gas-related activity would be located off the coasts of 

Louisiana, Mississippi, and western Florida. The greater distance between these activities and the 

coastal habitats of Texas would reduce impacts along the Texas coast whether from routine 

activities or accidental events. Less use of service bases in Texas is likely, and the distance 

between oil spills associated with this alternative and the Texas coast is expected to be greater.

4.3.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

The impacts of this alternative would be less than those under Alternative A, as only a 

fraction of the resulting activity forecasted for Alternative A is projected for Alternative C. For this 

alternative, there would be negligible incremental impacts to coastal barrier beaches and dunes in 

Louisiana; and zero to negligible impacts to Mississippi, Alabama, and the panhandle of western 

Florida; and incrementally more impacts to the beaches and dunes of Texas. However, Alternative 

C would have less potential for impact than Alternative A or B as the level of projected OCS oil- and 

gas-related activities and impact-producing factors are much less in the WPA. For example, a range 

of 11-67 production wells are projected to be drilled and developed under Alternative C, whereas 

58-464 production wells are projected to occur under Alternative B. The significance of impactproducing factors on coastal barrier beaches and dunes would be somewhat less for Alternative C 

than for Alternative A, as discussed in Chapter 2.2.2. 
Description of the Affected Environment and Impact Analysis 4-93

4.3.2.2.4 Alternative D—Alternative D—Alternative A, B, or C, with the Option to Exclude 

Available Unleased Blocks Subject to the Topographic Features, Live Bottom 

(Pinnacle Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

The impacts of this alternative would be nearly identical to those of the alternative it is 

combined with because the available unleased blocks with topographic features do not contain 

coastal barrier beaches and dunes and are too distant (over 25 km; 16 mi) from the coast to have 

indirect impacts. In addition, there are only 367 blocks subject to the Topographic Features 

Stipulation, 74 blocks subject to the Live Bottom (Pinnacle Trend) Stipulation, and 32 blocks subject 

to the Blocks South of Baldwin County, Alabama, Stipulation. This relatively small percentage of the 

total number of available unleased blocks would not be expected to generate a great contribution to 

OCS oil- and gas-related activity, if leased.

4.3.2.2.5 Alternative E—No Action

If a proposed lease sale does not occur, there would be no additional impacts to barrier 

beaches and associated dunes; however, cumulative impacts would be the same as for 

Alternative A. There could be some incremental increase in impacts caused by a compensatory 

increase in imported oil and gas to offset reduced OCS production, but it would likely be negligible. 

4.4 DEEPWATER BENTHIC COMMUNITIES

BOEM defines “deepwater benthic communities” as including both chemosynthetic 

communities (chemosynthetic organisms plus seep-associated fauna) and deepwater coral 

communities (deepwater coral plus coral-associated fauna). This chapter presents an analysis of 

the potential impacts on deepwater benthic communities as a result of routine activities and 

accidental events associated with a GOM proposed action and a proposed action’s incremental 

contribution to cumulative impacts. The analysis is not exhaustive of all possible impacts of routine 

activities and accidental events; rather, it focuses on those most relevant for decisionmakers. 

Potential impacts from a catastrophic oil spill, including long-term impacts and recovery, are detailed 

in the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2016c).

Because of the similarity and overlap of the effects of many activities that occur in the OCS, 

the primary, reasonably foreseeable routine and accidental impact-producing factors for deepwater 

benthic habitats can be grouped into three main categories:

(1) bottom-disturbing activities (Chapter 3.1.3.3.1; routine and accidental);

(2) drilling-related sediment and waste discharges (Chapter 3.1.5.1; routine and 

accidental); and 

(3) oil spills (Chapter 3.2.1; accidental).
4-94 Gulf of Mexico Multisale EIS

Cumulative Impacts were also considered, in two steps: impacts resulting from OCS oil- and 

gas-related activities (same as routine activities and accidental events); and impacts resulting from 

non-OCS oil- and gas-related sources, namely fishing and climate change.

Some impact-producing factors relevant to deepwater benthic communities are already 

analyzed in greater detail in other sections and need only be briefly summarized here. Chapter 4.7

(Fishes and Invertebrate Resources) details the potential impacts to marine invertebrates from 

anthropogenic sound and concludes the impact would be negligible. Note that despite the growing 

body of information available for fishes, there is comparatively little information available on sound 

detection and sound-mediated behaviors for marine invertebrates. Chapter 4.7 (Fish and 

Invertebrate Resources) also details the impacts of routine activities and the cumulative impacts 

from the presence and subsequent removal of OCS oil- and gas-related infrastructure. These 

impacts include the post-installation physical presence of OCS oil- and gas-related infrastructure, 

effects of decommissioning activities such as explosive and nonexplosive removals, and conversion 

of platforms to artificial reefs. While the total contribution of OCS infrastructure is still only a small 

percentage of natural hard bottoms (Gallaway et al., 2009), and is projected to further decrease 

throughout the period covered by this analysis (Chapter 3.3.1.5), the presence, removal, and/or 

conversion of artificial hard substrates colonized by sessile invertebrates are likely to result in 

localized community changes, such as changes in species diversity in the area (Schroeder and 

Love, 2004). While individual presence, removal, or conversion actions at specific locations do not 

cause more than negligible impacts when considered against the broader scope of this analysis, 

when the sum of such actions are considered cumulatively for all planning areas and over 50 years, 

such impacts could be greater for individual species . This is because select sessile benthic species 

commonly associated with OCS oil and gas structures could be noticeably influenced over time by 

the overall presence (or removal) of OCS oil- and gas-related infrastructure. For example, a 

particular deepwater coral species’ Gulfwide spatial distribution may shift over time because of the 

presence or removal of structures in otherwise soft bottom-dominated areas. Such a change (were 

it to occur) could be considered a moderate level impact for that species If it represented a 

detectable change in the species’ spatial distribution, such a range shift might have potential longterm effects related to dispersal and genetic connectivity to other populations of that species. Such 

potential impacts are not necessarily either positive or negative; that would be dependent on the 

species and a number of complex ecological factors. Some evidence of these types of changes (in 

particular, range expansion) has been documented for some shallow-water hermatypic species 

(Sammarco et al., 2012), but similar research specific to deepwater coral is lacking, as noted in the 

“Incomplete or Unavailable Information” section below. More peer-reviewed literature about this 

topic is available for fish resources, as detailed in Chapter 4.7. 

Several additional impact-producing factors described in Chapter 3.1 were evaluated for 

potential impacts on deepwater benthic communities. These impact-producing factors were not 

carried forward for full analysis because any potential effects were judged to be either not 

reasonably foreseeable or having such a miniscule impact that they would not rise to the level of 

negligible impact. These impact-producing factors include surface oil-spill response efforts (refer to 

Chapter 4.6.1, Topographic Features), impacts from geological and geophysical activities other than 
Description of the Affected Environment and Impact Analysis 4-95

bottom disturbance (bottom disturbance is covered below), and potential impacts from a sinking 

vessel. A sinking vessel settling on a deepwater benthic community is not a reasonably foreseeable 

impact-producing factor. Even if such an incident did occur, it would not have a population-level 

impact despite likely crushing or smothering deepwater benthic organisms in the local area of direct 

contact.

Some potential impact-producing factors are already regulated by other Federal agencies 

and/or international treaties. For example, the discharge of marine debris is subject to a number of 

laws and treaties (refer to Chapter 3.1.5.3.4). These include the Marine Debris Research, 

Prevention, and Reduction Act; the Marine Plastic Pollution Research and Control Act; and the 

MARPOL-Annex V Treaty. Regulation and enforcement of these laws is conducted by a number of 

agencies such as the U.S. Environmental Protection Agency, NOAA, and the U.S. Coast Guard. To 

further reduce potential impacts, the BSEE provides information on marine debris and requires 

training of all OCS personnel through the “Marine Trash and Debris Awareness and Elimination” 

NTL (NTL 2015-BSEE-G03). This NTL instructs OCS operators to post informational placards that 

outline the legal consequences and potential ecological harm of discharging marine debris. This 

NTL also states that OCS workers should complete annual marine debris prevention training; 

operators are also instructed to develop a certification process for the completion of this training by 

their workers. Typically, compliance with this NTL has been mandatory as a result of the Protected 

Species Stipulation that has been applied at the lease sale stage. These various laws, regulations, 

and NTL would likely minimize any potential damage to live bottom resources from the discharge of 

marine debris related to OCS oil- and gas-related operations. Nonetheless, some accidental release 

of marine debris is still likely to occur as a result of OCS oil- and gas-related operations and could 

theoretically have limited effects on deepwater benthic organisms (e.g., physical damage caused by 

strong currents pushing debris into fragile organisms or ingestion of plastics by invertebrates). 

However, the amount of debris in question would not suffice to cause even negligible impacts when 

considered at the scale of the overall population of deepwater benthic communities in the GOM. 

One possible exception would be frequent accidental losses of very large items such as pipeline 

segments with the potential to crush or smother organisms. That impact-producing factor is briefly 

discussed under “Accidental Events: Bottom-Disturbing Activities” below, even though any such 

losses are expected to be very rare. In all cases, the likelihood of spatial overlap with debris from 

OCS oil- and gas-related vessels or infrastructure is inherently small due to the relatively rare and 

patchy distribution of live bottom communities in the GOM, particularly in areas of the western and 

northern GOM, which have the greatest amount of OCS oil- and gas-related operations.

Another potential impact-producing factor that is largely governed by (and potential impacts 

reduced by) external regulations is the potential presence of toxins in drilling muds and cuttings 

and/or produced waters (Chapter 3.2.6). Because of the regulations issued by the USEPA and/or 

international treaties designed to keep toxins below harmful levels, hazardous levels of toxins are 

generally not expected to reach deepwater benthic communities. Nonetheless, potential impacts 

from toxins are briefly discussed under “Routine Activities” below.
4-96 Gulf of Mexico Multisale EIS

The impact significance criteria and resulting conclusions presented in Table 4-6 focus on 

the overall functioning, resilience, and ecosystem level importance of deepwater benthic 

communities throughout U.S. waters of the GOM. Postlease, site-specific analyses would focus 

more on potential localized impacts of individual development activities (e.g., proposed drilling of a 

well) to individuals, discrete communities, and small patches of benthic habitat. Those analyses 

would also detail site-specific protective mitigations required prior to approval of such activities.

Table 4-6. Deepwater Benthic Communities Impact-Producing Factors.

Deepwater Benthic 

Communities Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Bottom-Disturbing Activities and Drilling-related Sediment and Waste Discharges

Without Mitigation

Minor to Minor to Minor to Minor to

None

Major Moderate Moderate Major

With Mitigation Negligible Negligible Negligible Negligible None

Accidental Impacts

Bottom-Disturbing Activities and Drilling-Related Sediment and Operational Waste Discharges

Without Mitigation

Minor to Minor to Minor to Minor to

None

Major Moderate Moderate Major

With Mitigation Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Oil Spills

Without Mitigation

Minor to Minor to Minor to Minor to

None

Major Moderate Moderate Major

With Mitigation Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Cumulative Impacts

OCS Oil and Gas

With Mitigation Negligible to Negligible to Negligible to Negligible to Negligible to

Minor Minor Minor Minor Minor

Non-OCS Oil and Gas

Fishing and Climate 

Change (dependent 

on unpredictable 

future conditions)

Negligible to Negligible to Negligible to Negligible to Negligible to

Major Major Major Major Major

N/A = not applicable.

Impact-Level Definitions

For this analysis, the following definitions were used to categorize impacts to pinnacles and 

low-relief features:
Description of the Affected Environment and Impact Analysis 4-97

• Negligible – Impacts to deepwater benthic communities are largely 

undetectable. There is some potential for even undetectable impacts to cause 

slight changes to a local community’s species abundance and composition, 

community structure, and/or ecological functioning, but any such changes would 

be spatially localized, short term in duration, and would not alter the overall 

status of GOM deepwater benthic communities.

• Minor – Impacts to deepwater benthic communities are detectable but cannot be 

clearly distinguished from natural variation. Such impacts could result in 

changes to a local community’s species abundance and composition, community 

structure, and/or ecological functioning, but would be spatially localized, short 

term in duration, and would not alter the overall status of GOM deepwater 

benthic communities.

• Moderate – Impacts to deepwater benthic communities detectably cause 

substantial, population-level changes in species composition, community 

structure, and/or ecological functioning. These impacts would be expected to be 

spatially extensive but are expected to only temporarily alter the overall status of 

GOM deepwater benthic communities; long-term recovery to pre-impact levels is 

likely.

• Major – Impacts to deepwater benthic communities detectably cause substantial, 

population-level changes in species composition, community structure, and/or 

ecological functioning. These impacts would be expected to be spatially 

extensive and noticeably alter the overall status of GOM deepwater benthic 

communities such that long-term recovery to pre-impact levels is unlikely.

Historical Protections of Deepwater Benthic Communities

Protective measures have been developed over time based on the nature and sensitivity of 

various benthic habitats and their associated communities, as understood from decades of BOEMfunded and other environmental studies. NTL 2009-G40, “Deepwater Benthic Communities,” 

provides operators with relevant information and consolidates guidance for the avoidance and 

protection of the various types of potentially suitable habitat for chemosynthetic organisms and 

deepwater coral. As detailed in NTL 2009-G40, all plans submitted for permitted deepwater (300 m 

[984 ft] or greater) activities are reviewed for the presence of deepwater benthic communities that 

may be impacted by the proposed activity. Lessees must provide site-specific survey and narrative 

information regarding sensitive benthic features with each exploration plan (EP), development 

operations coordination document (DOCD), and development and production plan (DPP). These 

plans are reviewed by subject-matter experts on a case-by-case basis to determine whether a 

proposed operation could impact a benthic community. If an impact from drilling or other seafloor 

disturbance (e.g., anchors, anchor chains, rig emplacement, pipeline emplacement) is judged likely 

based on site-specific information derived from the geohazard survey data, BOEM’s databases and 

studies, other published research, or another creditable source, the operator would be required to 

relocate the proposed operation (i.e., distancing) or undertake other appropriate mitigations to 
4-98 Gulf of Mexico Multisale EIS

prevent such an impact. As detailed above, BOEM’s subject-matter experts make use of the best 

available datasets to identify probable habitat that could support deepwater chemosynthetic and 

coral communities, including BOEM’s publicly available database of water-bottom anomalies 

(USDOI, BOEM, 2015c). This analysis assumes continuation of the protective measures outlined in 

NTL 2009-G40.

4.4.1 Description of the Affected Environment

Chemosynthetic communities are formed around natural hydrocarbon seepages where 

bacteria consume methanes and sulfides and chemosynthetically derive amino acids and sugars for 

respiration, and then excrete carbon dioxide that may result in calcium carbonate precipitation. 

Eventually, sufficient precipitates can form hard carbonate substrates on which higher order 

organisms such as structure-forming deepwater sponges and corals can settle. Relatively large 

numbers of invertebrate and fish species may be attracted to structurally complex microhabitats, 

which can provide shelter, feeding areas, and nursery grounds (Fraser and Sedberry, 2008). Over 

330 chemosynthetic communities have been confirmed in the GOM to date; more communities likely 

exist but much of the seafloor has not yet been visually surveyed. Much is still unknown about these 

communities, despite increasing research in recent decades.

Deepwater coral communities are known to occur throughout the GOM (Figure 4-12) and 

new communities are routinely discovered with almost every new deepwater research cruise 

(USDOC, NOAA, 2014). As with shallow-water live bottom communities (Chapter 4.6), almost all 

GOM deepwater corals require exposed hard substrate for attachment and growth. They often 

co-occur on authigenic substrates (substrates that have been generated where they are found)

created by chemosynthetic processes; however, they also routinely colonize other natural or artificial 

hard substrates not associated with hydrocarbon seepage. In addition to hard and soft deepwater 

corals, these communities include other associated sessile and motile fauna such as sponges, 

anemones, echinoderms, crustaceans, and fishes.
Description of the Affected Environment and Impact Analysis 4-99

Figure 4-12. Deepwater Coral Records from NOAA’s National Deep-Sea Coral and Sponge 

Database (USDOC, NOAA, 2014).

Gulf of Mexico Continental Slope and Deepwater Biological Resources

The northern GOM’s continental slope region has been described as the most complex in the 

world (Carney, 1997 and 1999; Rowe and Kennicutt, 2009). It is a transitional environment 

influenced by processes of both the shelf (<650 ft; 200 m) and the abyssal GOM (>3,199 ft; 975 m). 

This transitional character applies to both the pelagic and the benthic realms. Regional topography 

of the slope consists of basins, knolls, ridges, and mounds derived from the dynamic adjustments of 

salt to the introduction of large volumes of sediment over long time scales.

Deepwater environments of the GOM have only been well studied in recent decades; 

historically there have been relatively few studies due to the logistical difficulties involved in 

deepwater research. The first substantial collections of deep GOM benthos were made during the 

cruises of the USCG and Geodetic Steamer, Blake, between 1877 and 1880. Rowe and Menzel

(1971) reported the first quantitative data published about GOM infauna for this region. Texas A&M 

University researchers performed the first major study of the deep northern GOM between 1964 and 

1973 (Pequegnat, 1983). A more recent study was completed by LGL Ecological Research 

Associates and Texas A&M University in 1988 (Gallaway et al., 1988). The major Northern Gulf of 

Mexico Continental Slope Habitats and Benthic Ecology Study (Rowe and Kennicutt, 2009) lasted 

6 years. The recent studies provide extensive background information on deepwater GOM habitats 

and biological communities relevant to this analysis and can be referenced for more detail.

The proposed lease sale area encompasses a vast range of habitats and water depths. The 

shallowest portions start nearshore at the boundary of State waters, and the deepest portions extend 

to approximately 11,483 ft (3,500 m) south of the Sigsbee Escarpment (which is centrally located in 

the Gulf of Mexico), nearly into the deepest part of the GOM (14,383 ft; 4,384 m). De Soto and 

Mississippi Canyons are perhaps the two most notable geologic seafloor features in the northern 

GOM, exerting control over water currents, upwelling features, and biological productivity. The 
4-100 Gulf of Mexico Multisale EIS

sediment-laden freshwater plume from the Mississippi River and the Gulf Loop Current are the major 

controlling oceanographic factors in the GOM.

“Deepwater” is a term of convenience used in this analysis to refer to water depths greater 

than 300 m (984 ft). The majority of deepwater seafloor in the GOM is typically covered by clay and 

silt (Jenkins, 2011). In, on, and directly above these sediments live a wide variety of “benthos,” or 

benthic organisms, from microbiota up through megafauna. Their ecological adaptations are 

extremely varied and can include absorption of dissolved organic material, symbiosis, collection of 

food through filtering, mucous webs, seizing, or other mechanisms, including chemosynthesis.

Deepwater fauna can be grouped into major assemblages defined by depth: (1) upper 

slope; (2) mid-slope; (3) lower slope; and (4) abyssal plain (Rowe and Kennicutt, 2009). The 450-m 

(1,476-ft) depth contour delimits the approximate beginning of the aphotic zone where visible light no 

longer penetrates and where photosynthesis cannot occur, with resultant changes to processes of 

food consumption, biological decomposition, and nutrient regeneration. The continental shelf-slope 

transition zone begins at approximately 150 m (492 ft) and the abyssal zone begins at approximately 

≥1,000 m (3,281 ft). The different zones can be subdivided into the following divisions and 

characteristic faunal assemblages:

• Shelf-Slope Transition Zone (150-450 m; 492-1,476 ft)—A very productive part of 

the benthic environment. Demersal fish are dominant, many reaching their 

maximum populations in this zone. Asteroids, gastropods, and polychaetes are 

common.

• Archibenthal Zone – Horizon A (475-740 m; 1,558-2,428 ft)—Although less 

abundant, demersal fish are a major constituent of the fauna, as are gastropods 

and polychaetes. Sea cucumbers are more numerous.

• Archibenthal Zone – Horizon B (775-950 m; 2,543-3,117 ft)—This zone 

represents a major change in the number of species of demersal fish, asteroids, 

and echinoids, which reach maximum populations here. Gastropods and 

polychaetes are still numerous.

• Upper Abyssal Zone (1,000-2,000 m; 3,281-6,562 ft)—Number of fish species 

decline while the number of certain invertebrate species appear to increase. Sea 

cucumbers and galatheid crabs are common

• Mesoabyssal Zone (2,300-3,000 m; 7,546-9,843 ft)—Fish species are few, and 

echinoderms continue to dominate the megafauna.

• Lower Abyssal Zone (3,200-3,800 m; 10,499 to 12,468 ft)—A large asteroid is 

the most common megafaunal species.

• The lowermost layer is the benthic zone, defined as the seafloor itself and the 

waters immediately above it. This zone is a repository of sediments where 

nutrient storage and regeneration take place in association with the solid and 
Description of the Affected Environment and Impact Analysis 4-101

semisolid substrate (Pequegnat, 1983). Characteristic fauna may be different 

depending on the actual depth of the seafloor.

The vast majority of the GOM seabed is comprised of soft sediments (Rezak et al., 1983; 

Jenkins, 2011). Sediments in the EPA consist primarily of sand, while a more heterogeneous mix of 

sand, silt and clay sediments are found in the CPA and WPA (Brooks and Darnell, 1991). Grain size 

is the most important substrate characteristic affecting the distribution of benthic fauna (Vittor, 2000). 

Major groups of animals that live in sediments include (1) megafauna (visible to the naked eye), 

(2) macrofauna (>0.01 in; 0.3 mm), (3) meiofauna (0.002-0.01 in; 0.063-0.3 mm), and (4) bacteria 

and other microbiota. All of these groups are represented throughout the entire GOM − from the 

continental shelf to the deepest abyssal depths. This analysis focuses on the better known 

megafauna and their habitats.

4.4.1.1 Chemosynthetic Communities

Chemosynthetic communities begin with chemosynthetic bacterial mats that consume 

methane and sulfides; their respiration results in the precipitation of calcium carbonate, forming a 

new, hard substrate. Certain deepwater coral and sponge species can then attach to exposed hard 

substrates, thereby adding to the structural complexity of the microhabitat. The new benthic habitats 

provided by chemosynthetic fauna themselves (i.e., tubeworm bushes), the precipitated hard 

substrates, and the framework-forming corals can all be used by a variety of benthic invertebrates, 

including echinoderms (e.g., brittle stars and basket stars), sea anemones, crustaceans, and other 

benthic megafauna such as fishes, forming a broader chemosynthetic community.

The GOM has some of the most active natural oil and gas seeps in the world (refer to 

Chapter 3.3.2.9.2; NRC, 2003), and these seeps can support development of complex deepwater 

faunal communities (MacDonald, 1993; Cordes et al., 2010). The food chain for this ecosystem 

relies on bacterial primary producers that consume methanes and sulfides rather than performing 

photosynthesis. Chemosynthetic bacteria, which live on mats, in sediment, and in symbiosis with 

chemosynthetic invertebrates, use a carbon source independent of photosynthesis to make sugars 

and amino acids. Chemosynthetic invertebrates including tube worms and bivalves occur at or near 

hydrocarbon seeps and are dependent upon these symbiotic chemosynthetic bacteria as their 

primary food source (MacDonald, 1992). The bacteria live within specialized cells in the invertebrate 

organisms and are supplied with oxygen and chemosynthetic compounds by the host via specialized 

blood chemistry (Fisher, 1990). The host, in turn, lives off the organic products subsequently 

released by the chemosynthetic bacteria and may even feed on the bacteria themselves.

Distribution and Detection

Chemosynthetic communities typically occur in the GOM at water depths greater than 300 m

(984 ft). Temperatures at these depths range from about 55°F to 39°F (13°C to 4°C). Water 

currents at the seafloor are typically about 2-4 inches/second (5-10 centimeters/second). The 

chemosynthetic communities occur as widely scattered, patchy habitat, developing where 

hydrocarbons seep up with a moderate flow.
4-102 Gulf of Mexico Multisale EIS

Seeps occur where hydrocarbons vertically migrate up through faults, fractures along the 

flanks of salt, or other conduits to the seafloor. The exact number of natural oil prone seeps in the 

GOM is not known, although volume estimates have been made using surface oil slicks and the 

numbers are considerable (MacDonald et al., 1993; NRC, 2003). Even less is known about the 

number and flux of gas prone seeps in the GOM since no observable sea-surface slicks are present. 

What is known is that the overwhelming majority of seeps are gas prone, not oil prone. Hydrocarbon 

source rocks occur over broad areas several kilometers beneath the seafloor of the GOM, but 

chemosynthetic communities occur in isolated areas at the seafloor. Seepage from deep 

hydrocarbon sources through subsurface conduits tends to be focused through the sediments, 

carbonate outcrops, and hydrate deposits at the seafloor. Therefore, GOM hydrocarbon seep 

communities tend to be larger (a few hundred meters wide) than chemosynthetic communities found 

around the hydrothermal vents of the Eastern Pacific (MacDonald, 1992).

As of 2015, at least 330 chemosynthetic communities have been confirmed (by government, 

academia, and industry) to exist in the Gulf of Mexico (Figure 4-13). Chemosynthetic communities 

dependent on hydrocarbon seepage have been documented in water depths as shallow as 951 ft 

(290 m) (Roberts et al., 1990) and at least as deep as 9,000 ft (2,743 m) (Roberts, 2010). But these 

known depth limits may only be reflective of the current limits of exploration due to the logistic 

difficulties of deepwater research; relatively few available submersibles are capable of exploring 

deeper than 3,281 ft (1,000 m). Given the rapid rate of discovery and improved understanding in 

recent years, the evidence suggests chemosynthetic communities could be more prevalent than 

once thought.

Figure 4-13. Estimated Distribution of Known Deepwater Benthic Communities in the Gulf of 

Mexico as of 2015.
Description of the Affected Environment and Impact Analysis 4-103

Hydrocarbon seeps and chemosynthetic communities living on them modify the near-surface 

geological characteristics in ways that can be remotely detected, such as through 2D and 3D 

seismic anomaly detection (USDOI, BOEM, 2015c). These known sediment modifications include 

the following: (1) precipitation of authigenic carbonate in the form of interstitial cements, 

micronodules, nodules, or rock masses; (2) formation of gas hydrates; (3) modification of sediment 

composition through concentration of hard chemosynthetic organism remains (such as shell 

fragments and layers); (4) formation of interstitial gas bubbles or hydrocarbons; and (5) formation of 

depressions or pockmarks by gas expulsion. These features give rise to various detectable acoustic 

effects (details in Behrens, 1988; Roberts and Neurauter, 1990). Potential locations for most types 

of communities can be estimated by careful interpretation of these various geophysical modifications 

(Sager, 1997) and can help direct and focus follow-up visual surveys needed to definitively confirm 

the presence or absence of chemosynthetic communities.

BOEM’s subject-matter experts make use of the best available datasets to identify probable 

habitat that could support deepwater benthic communities. A primary such dataset is BOEM’s 

publicly available database of water-bottom anomalies (USDOI, BOEM, 2015c). Using decades of 

3D seismic amplitude data, BOEM geoscientists have identified and mapped over 31,000 waterbottom (seafloor) acoustic amplitude anomalies covering a majority of the deep waters in the 

northern Gulf of Mexico (Figure 4-14). One of the purposes of this effort is to better understand the 

distribution of natural hydrocarbon seeps and related chemosynthetic communities and deepwater 

coral communities. The areas of anomalously high or low seafloor reflectivity have been classified 

into general categories of seafloor features, including those that are thought to support 

chemosynthetic and deepwater coral communities (USDOI, BOEM, 2015c). As of 2015, BOEM is 

aware of a total of 332 seep anomalies that have been visually confirmed through photography, 

video, and manned submersible dives to contain associated chemosynthetic and/or coral 

communities (Figure 4-14, shown in orange); however, that relatively low number is largely due to a 

lack of visual survey effort required for definitive visual confirmation. Several of the other anomaly 

categories may also contain potential habitat capable of supporting deepwater chemosynthetic and 

coral communities. Additional information is being collected and analyzed by BOEM’s geoscientists 

and provided to BOEM’s subject-matter experts on an ongoing basis.
4-104 Gulf of Mexico Multisale EIS

Figure 4-14. BOEM’s Water Bottom Seismic Anomaly Database Showing Grouped Anomaly 

Categories Thought Likely to Support Deepwater Benthic Communities (shown in 

orange) and Those That Generally Do Not (shown in purple)

Biology

MacDonald et al. (1990) described four general community types: (1) tube worms; 

(2) mussels; (3) clams at the seafloor surface; and (4) burrowing clams. These faunal groups tend 

to display distinctive characteristics in terms of how they aggregate, the size of aggregations, the 

geological and chemical properties of the habitats in which they occur, and (to some degree) the 

heterotrophic fauna associated with them. Individual tube worms can reach lengths of over 10 ft 

(3 m) and live hundreds of years (Fisher et al., 1997). Average growth rates determined from 

marked tube worms have been variable, but they average approximately 7.1 millimeters/year 

(0.28 inches/year) for some species. Tube worm spawning and recruitment is episodic. Mytilid 

mussels have been found to reach reproductive age relatively quickly, with growth rates slowing in 

adulthood (Fisher, 1995). These factors lead to long-lived individuals and communities. Powell 

(1995) estimated that some clam and mussel communities at chemosynthetic sites have been 

present in the same location for between 500 and 4,000 years, with most communities showing no 

evidence of changes in the dominant faunal organisms over time. Local extinctions and 

recolonizations are likely gradual and rare.

Other common heterotrophic organisms often found at chemosynthetic community sites 

include a variety of mollusks, crustaceans, and echinoderms (Carney, 1993). Extensive mats of 

free-living bacteria are also evident at hydrocarbon seep sites. These bacteria may compete with 

the major fauna for sulfide and methane energy sources and may also contribute substantially to 
Description of the Affected Environment and Impact Analysis 4-105

overall production (MacDonald, 1998). Some of the species found at GOM seep communities are 

new to science and remain undescribed.

Persistence

According to Sassen (1998), the role of naturally occurring methane hydrates to influence the 

morphology and characteristics of chemosynthetic communities has been greatly underestimated. 

Gas hydrates are a unique and poorly understood class of chemical substances. The dynamics of 

hydrate alteration could play a major role in the release of hydrocarbon gases to fuel biogeochemical 

processes and could influence community stability (MacDonald, 1998). Changes in bottom-water 

temperature of several degrees (39-41 °F [4-5 °C] at 1,640-ft [500-m] depth) may result in 

dissociation of hydrates and an accompanying increase in gas fluxes (MacDonald et al., 1994). 

Although not as destructive as the volcanism at vent sites of the mid-ocean ridges, the dynamics of 

shallow hydrate formation and movement could clearly affect sessile animals around the seepage 

barrier because of the potential for an entire layer of shallow hydrate to break free of the bottom, 

which would result in considerable impacts to local communities of chemosynthetic fauna. At deeper 

depths (>3,281 ft; >1,000 m), the bottom-water temperature is colder and undergoes less fluctuation.

Precipitation of authigenic carbonates and other geologic events would alter surface 

seepage patterns and available substrates over periods of only a few years. However, through 

taphonomic (death assemblages of shells) studies and interpretation of seep assemblage 

composition from cores, Powell (1995) reported that, overall, seep communities were persistent over 

periods of 500-4,000 years. Powell found few cases in which the community type changed (from 

mussel to clam communities, for example) over time. When recovery occurred after a past 

destructive event, the same chemosynthetic species reoccupied a site. MacDonald et al. (1995) 

observed no changes in chemosynthetic fauna distribution or composition at seven separate study 

sites. In the case of one well-known chemosynthetic community (Bush Hill), no mass die-offs or 

large-scale shifts in faunal composition were observed over 12 years of research.

4.4.1.2 Deepwater Coral Communities

Deepwater corals are sessile invertebrates in the phylum Cnidaria. They live at great depths 

(as deep as 10,000 ft [3,048 m] in some cases) where there is little to no light. As with the better 

known shallow-water corals, deepwater corals are colonial animals. Individual polyps extend 

tentacles into passing currents to feed on nutrients, which can be relatively scarce at depth. Energy 

supply is further limited by the lack of light-dependent mutualistic zooxanthellae algae that benefit 

many shallow-water coral species. As a result, deepwater coral colonies grow very slowly; colonies 

may live to be hundreds or even thousands of years old (USDOC, NOAA, 2014).

Deepwater corals are found in all the world’s oceans and actually have a higher overall 

diversity of species than shallow-water coral (Cairns, 2007). Yet it is only in recent decades that 

they have become a focus of scientific research (Freiwald et al., 2004) and management concern 

(USDOC, NOAA, 2014; CSA, 2002), as anthropogenic threats such as bottom disturbance (e.g., 

from fishing gear) have become more clear. Their very slow growth rates and fragile skeletal 
4-106 Gulf of Mexico Multisale EIS

structures make them especially vulnerable to physical disturbance. Once damaged, deepwater 

corals and the associated communities they support may take centuries to fully recover (USDOC, 

NOAA, 2014).

In the GOM, almost all deepwater corals are found attached to exposed surfaces of hard 

substrates. These substrates include chemosynthetically produced carbonate substrates (Chapter 

4.4.1.1), but they can also include exposed sedimentary bedrock and even artificial structures such 

as shipwrecks and oil platforms.

Some species of deepwater corals and sponges are known to create large, threedimensional structures, which are sometimes referred to as deepwater reefs. Some of these have 

grown many feet tall over time. Structure-forming corals include branching scleractinian species, 

Antipatharians (black corals) and gorgonians (sea whips/sea fans). Lophelia pertusa, the most wellknown scleractinian deepwater coral, can form vast reef-like thickets that can stretch to over 3,280 ft 

(1,000 m) in surface extent. In a historic 1955 trawl collection from a depth of 1,381-1,680 ft 

(421-512 m), Moore and Bullis (1960) retrieved more than 300 pounds (136 kilograms) of Lophelia

pertusa from the Viosca Knoll area in the CPA.

Similar to shallow-water live bottom microhabitats (Chapter 4.6), deepwater coral 

microhabitats enhance the structural complexity of the local environment, providing shelter, feeding 

sites, and nursery grounds that are attractive to a large variety of other invertebrates and fishes, 

including a few commercially harvested species (Schroeder et al., 2005; Fisher et al., 2007; Fraser 

and Sedberry, 2008; Sulak et al., 2008; Cordes et al., 2008; USDOC, NOAA, 2014; Hourigan, 2014). 

Common crustaceans include golden crab (Chaceon fenneri) and squat lobster (Eumunida picta). 

Common echinoderms include brittle stars (order Ophiurida) and baskets stars (order Euryalida). 

Deepwater reef-associated fish are known to include barrelfish (Hyperoglyphe perciformis), 

wreckfish (Polyprion americanus), and snowy grouper (Epinephelus niveatus) at shallower locations 

and blackbelly rosefish (Helicolenus dactylopterus), roughys (Hoplotsethus spp.), and thornyheads 

(Sebastolobus spp.) at deeper sites (Hourigan, 2014; refer to Chapter 4.7).

Distribution

Distribution of individual deepwater coral and associated species assemblages is influenced 

by depth, available substrate, and other environmental conditions such as bottom currents. At least 

six different types of octocoral assemblages occur in the deep northwestern Gulf and the West 

Florida Slope at depths of 820-8,200 ft (250-2,500 m). The black coral, Leiopathes spp., appears 

broadly distributed across both regions. Although Lophelia pertusa is best represented in water 

depths of the upper slope, it has occasionally been reported as deep as 9,842 ft (3,000 m) in some 

parts of the world.

The NOAA’s Deep Sea Coral Research and Technology Program and NOAA’s National 

Centers for Coastal Ocean Science have been continuously compiling a detailed national database 

of known observations of deepwater corals and sponges (USDOC, NOAA, 2014 and 2015) 
Description of the Affected Environment and Impact Analysis 4-107

(Figures 4-12 and 4-13), but these confirmed visual observations likely represent only a fraction of 

the populations. Deepwater research cruises, for example those undertaken by the NOAA deep-sea 

research vessel Okeanos Explorer, routinely discover additional deepwater coral locations. 

However, even with ongoing additions of observation records, the majority of deepwater coral 

communities would not be directly observed and documented in the near future due to the inherent 

logistical difficulties of deepwater research and data collection.

Figure 4-15. Example of a Predictive Habitat Suitability Model for Selected Deepwater, 

Framework-Forming Scleractinian Corals (excerpted with permission from 

USDOC, NOAA, 2014).

Therefore, extrapolative analyses such as one undertaken by NOAA (Figure 4-15) have also 

included efforts to predictively model suitable habitat for deepwater coral and sponges, based on 
4-108 Gulf of Mexico Multisale EIS

existing observation records combined with the best available physical datasets. These models can 

serve as an important tool to help identify where deepwater coral communities are likely to be found 

and to help focus future data collection and research efforts. For example, based in part on previous 

databases and models, the Gulf of Mexico Fishery Management Council (GMFMC) is currently 

evaluating advisory panel recommendations to designate up to 47 new, small areas as deepwater 

coral Habitat Areas of Particular Concern (CSA, 2002). Future research, including a planned 

BOEM-funded study (Interagency Agreement #M15PG00020), may improve on previous deepwater 

coral modeling and expand to include chemosynthetic communities.

4.4.2 Environmental Consequences

Routine Activities

A number of routine OCS oil- and gas-related impact-producing factors may cause adverse 

impacts to deepwater benthic communities. As noted above, some factors with only minimal 

impacts are presented in greater detail in other chapters, and full analyses are not repeated here. 

The potential routine impact-producing factors on deepwater benthic habitats analyzed here are 

grouped into two main categories having similar impacts: (1) bottom-disturbing activities; and 

(2) drilling-related sediment and waste discharges. These impact-producing factors have the 

potential to damage deepwater benthic habitats and disrupt associated communities if not 

sufficiently distanced via mitigations.

Bottom-disturbing activities can be described as any activities that result in the physical 

disturbance of the seafloor during the exploration, production, or decommissioning phase of OCS 

operations (refer to Chapters 3.1.2, 3.1.3.3, and 3.1.6). Anchoring, drilling, trenching, pipe-laying, 

and structure emplacement and removal are examples of OCS oil- and gas-related activities that 

disturb the seafloor (refer to Chapters 3.1.3.3 and 3.1.6). The spatial extent of the seafloor 

disturbance and the magnitude of the effect on deepwater benthic organisms would depend on the 

specific activity, local environmental conditions (e.g., currents, water depth, etc.), and speciesspecific behaviors and habitat preferences.

Drilling of new wells is one of the activities with the greatest impact potential due to the 

associated sedimentation/turbidity caused by the drilling process and from the release of drilling 

cuttings and discharges (Chapter 3.1.5.1). Drilling an exploratory well produces approximately 

2,000 metric tons of combined drilling fluid and cuttings, though the total mass may vary widely for 

different wells (Neff, 2005). Cuttings discharged at the surface tend to disperse in the water column 

and be distributed at low concentrations (CSA, 2004). In deep water, the majority of cuttings 

discharged at the sea surface are likely to be deposited within 820 ft (250 m) of the well (CSA, 

2006). Cuttings shunted to the seafloor form piles concentrated within a smaller area than do 

sediments discharged at the sea surface (Neff, 2005).

Turbidity from suspended sediments, along with sediment displacement resulting from 

routine, bottom-disturbing oil- and gas-related activities, generally has localized effects. Impacts to 

deepwater benthic communities could include any or all of the following: reduced settlement and 
Description of the Affected Environment and Impact Analysis 4-109

growth opportunities due to loss of available hard substrate; inhibited feeding leading to reduced 

reproductive fitness; and mortality of individuals (e.g., coral polyps and 1 or 2 tubeworms) and 

groups (e.g., entire coral colonies and tubeworm “bushes”). Reductions in overall biological cover 

could have secondary ecological effects on organisms that were using the complex structural 

microhabitats, for example the loss of a shark spawning ground (some sharks deposit eggs in 

deepwater coral [Etnoyer and Warrenchuk, 2007]) that reduces future shark populations. Some 

mobile invertebrates (e.g., brittle stars) are expected to be able to move to avoid the heaviest 

sediment displacement and highest suspended sediment loads within 33 ft (10 m) of a disturbance, 

while sessile invertebrates (e.g., corals) cannot. Sessile and mobile invertebrate species adapted to 

living in turbid environments, such as many gorgonians, may be less affected by increased turbidity. 

Such organisms may also be adapted to remove some covering sediment via tentacle motion and 

mucus secretion (Shinn et al., 1980; Hudson and Robbin, 1980). Other species that typically inhabit 

less turbid waters would suffer relatively greater impacts (Rogers, 1990; Gittings et al., 1992a). 

Solitary octocorals and gorgonians may be tolerant of a certain amount of sedimentation, partly 

because they grow tall and are flexible, reducing sediment accumulation and allowing for easier 

removal (Marszalek, 1981; Torres et al., 2001; Gittings et al., 1992a), but are not completely resilient 

to impacts (Doughty et al., 2014).

Apart from the direct impacts of turbidity and sedimentation, the chemical content of drilling 

muds and cuttings (and, to a lesser extent, produced waters) are another potential impact-producing 

factor since these may contain hydrocarbons, trace metals including heavy metals, elemental sulfur, 

and radionuclides (Kendall and Rainey, 1991; Trefry et al., 1995). Substances containing heavy 

metals and other potentially toxic compounds would have the potential to be moderately toxic to 

deepwater benthic organisms, but only if they were to come into contact in undiluted strengths (CSA, 

2004b). Although the literature has not reported impacts to chemosynthetic organisms, gorgonians, 

or soft corals as a result of exposure to contaminants in cuttings, infauna have shown effects at 

distances <330 ft (<100 m) from the discharge. These include reduced reproductive fitness, altered 

populations, and acute toxicity (Montagna and Harper, 1996; Carr et al., 1996; Kennicutt et al., 1996; 

Hart et al., 1989; Chapman et al., 1991; CSA, 2004b). Because of BOEM’s distancing requirements 

for new wells, contact with concentrated (and potentially harmful) levels of any such toxins is not 

expected. As they travel from a source, produced waters (refer to Chapter 3.1.5.1.2 for more detail) 

are rapidly diluted with distance, and impacts are generally only observed within very close proximity 

of the discharge point (Gittings et al., 1992a; Neff, 2005). In addition to the protection offered by 

BOEM’s distancing requirements, releases of toxic discharges are regulated by the USEPA through 

the issuance of NPDES permits. Adherence to these regulations would help ensure that water 

quality is maintained at nontoxic levels.

In addition to drilling activities, the process of installing and removing OCS oil- and gasrelated infrastructure (i.e., pipelines, platforms, and subsea systems including cables) also has the 

potential to displace large volumes of sediment (Chapter 3.1.3.3). The resulting localized increases 

in turbidity and sedimentation would have the same indirect impacts as those caused by drillingrelated sediment movement.
4-110 Gulf of Mexico Multisale EIS

The OCS oil- and gas-related infrastructure/equipment also has the potential to damage or 

kill deepwater benthic organisms should the equipment itself make direct contact. Any object placed 

on or through (e.g., a piston-driven core sampler) a deepwater benthic organism or supporting 

substrate can cause partial or complete breakage, crushing, or smothering. In addition to mortality, 

there could be any or all of the potential sublethal impacts already described above in relation to 

turbidity and sediment displacement. The severity of community impacts from direct physical 

contact would vary in direct proportion to the surface area and mass of the specific equipment. For 

example, the placement of a large bottom-founded platform on a deepwater benthic community 

would have a much greater impact than placement of a small umbilical cable.

Similarly, anchor damage is one of the greatest threats to benthic biota in the GOM (Rezak 

and Bright, 1979; Rezak et al., 1985; Gittings et al., 1992a; Hudson et al., 1982). Anchors may 

break, fragment, or overturn tubeworms, bivalves, corals, sponges, or any other sessile benthic 

organisms, and the anchor chain or cable may drag across and shear organisms off the substrate 

(Dinsdale and Harriott, 2004). This would result in consequences ranging from increased stress to 

mortality (Dinsdale and Harriott, 2004). The impact of dragging an anchor across a deepwater 

benthic community would depend on the distance and duration of bottom contact, but it could be 

considerable due to the forces involved; dragged anchors often leave seafloor scars noticeable on 

sidescan sonar imagery years later. Damage to a coral community may take decades to recover 

(Fucik et al., 1984; Rogers and Garrison, 2001).

As further detailed in other chapters, explosive severance methods used during 

decommissioning activities could result in damage or mortality to any organisms within the vicinity of 

the blast or associated sediment plume, although long-term turbidity is not expected from platform 

removal operations. The shockwave from a nearby blast could also damage or destroy the 

underlying hard substrates required to support some deepwater benthic communities. The BSEE 

Interim Policy Document 2013-07, “Rigs-to-Reefs Policy,” specifies that the use of explosive 

severance methods would not be approved if analysis determines they would cause harm to natural 

deepwater benthic communities.

Compared with shallow-water live bottom communities, some deepwater benthic organisms 

may be slower to recover from any of the impacts described above due to the generally much slower 

growth and recruitment rates that are typical of these longer-lived species and communities (Powell, 

1995). For example, Doughty et al. (2014) demonstrated that Paramuricea spp., some of the most 

common deepwater corals in the GOM, may have very low recruitment rates and therefore slow 

recovery.

Potential impacts resulting from all of the above routine activities are mitigated through the 

protective measures (primarily distancing) described above and in NTL 2009-G40. The postlease, 

site-specific survey information and mitigation options described in NTL 2009-G40 would allow 

BOEM to identify and sufficiently distance deepwater benthic features from any proposed OCS oiland gas-related routine activity during postlease reviews. If all of these requirements are applied as 
Description of the Affected Environment and Impact Analysis 4-111

expected, at the scope of this analysis, the impacts of routine activities would be expected to be 

negligible. 

Without adherence to those requirements or absent expected USEPA restrictions on 

discharges, impacts to deepwater benthic communities from the above routine activities could rise to 

minor, moderate, or even major, depending on the number and locations of specific activities. The 

highest impact levels are possible in the improbable (but theoretically possible) case that a large 

number of routine activity disturbances were to physically impact a large number of deepwater 

benthic communities. Even without mitigations, the likelihood is very low that a large number of 

OCS oil- and gas-related activities would occur in close proximity because the hard substrate 

habitats supporting deepwater benthic communities are patchily distributed throughout the GOM and 

are relatively rare compared with soft bottom substrates. But this possibility cannot be definitively 

ruled out without knowing both the precise spatial distribution of both future OCS oil- and gas-related 

activities and deepwater benthic communities.

Accidental Events

The primary accidental impact-producing factors affecting deepwater benthic communities 

analyzed here are grouped into two categories: (1) bottom-disturbing activities; and (2) oil spills 

(surface and subsurface) and associated clean up responses. These factors have the potential to 

damage deepwater benthic habitats and disrupt associated benthic communities if not sufficiently 

distanced or otherwise mitigated.

Bottom-Disturbing Activities

Impacts resulting from bottom-disturbing activities were already detailed in “Routine 

Activities” section above and are largely the same for accidental events. There are only slight 

differences that need to be considered here and are related to mechanisms and potential severity. 

The primary, accidental bottom-disturbing activity is the inadvertent deposition or placement of 

equipment on deepwater habitats. Accidental loss of equipment could occur during transfer 

operations between vessels and platforms, during vessel transit, during an “on deck” accident, as a 

consequence of a severe storm, or if a structure, drill, or anchor is unintentionally placed in the 

wrong location during operations. During routine operations, the distancing mitigations offer some 

protections against these types of impact, but those protections may not apply to all accidents, other 

than to reduce the likelihood of routine activities occurring in those areas in the first place. Any 

object placed on or through a deepwater benthic habitat could cause partial or complete breakage, 

crushing, or smothering of both substrate and organisms, and/or increased sedimentation as 

equipment disturbs the seafloor. In addition to mortality, deepwater benthic communities could 

experience any or all of the potential sublethal impacts already described in the “Routine Activities” 

section above. The severity of impacts from direct physical contact would vary in direct proportion to 

the surface area and mass of the specific equipment. Given the relative rarity of deepwater benthic 

habitats and communities in the GOM, accidental impacts from bottom-disturbing equipment are 

expected to be infrequent and highly localized, with the likelihood of accidental contact further 

reduced by the expected distancing mitigations. However, because of the unplanned and potentially 
4-112 Gulf of Mexico Multisale EIS

uncontrolled nature of accidental bottom-disturbing events, there exists greater uncertainty about 

their potential impact severity than exists for planned routine activities. Therefore, at the scale of this 

analysis, impacts to deepwater benthic communities could range from negligible to minor, 

depending on their overall frequency and severity and whether or not community-level accidental 

impacts can be clearly distinguished from natural variation.

Without the protective mitigations provided by postlease reviews and distancing, the potential 

impacts of accidental bottom disturbances could rise to moderate or even major levels, in the 

improbable (but theoretically possible) case that a large number of accidental disturbances were to 

physically impact a large number of deepwater benthic communities. Even without mitigations, the 

likelihood is very low that a large number of OCS oil- and gas-related activities would occur in close 

proximity to the relatively rare hard substrate habitats supporting deepwater benthic communities, 

but this possibility cannot be definitively ruled out without knowing both the precise spatial 

distribution of both future OCS oil- and gas-related activities and deepwater benthic communities.

Oil Spills and Associated Impacts

Oil spills, historic trends, the characteristics of oil, and factors affecting the fate of oil 

released into the marine environment are discussed in detail in Chapter 3.2.1 (Oil Spills), and the 

potential impacts to water quality are analyzed in Chapter 4.2 (Water Quality). For additional 

information on impacts resulting specifically from a catastrophic spill, refer to the Catastrophic Spill 

Event Analysis white paper (USDOI, BOEM, 2016c).

Impacts related to an accidental release of oil or other contaminants could adversely affect 

deepwater benthic communities. Potential impacts related to an accidental spill would depend on 

the combination of these various components: surface oil; subsurface oil; chemical dispersants and 

dispersed oil; sedimented oil (oil adsorbed to sediment particles); sedimentation caused by a loss of 

well control; and certain spill-response activities. Adherence to well-distancing requirements should 

serve to reduce such impacts.

Biological impacts resulting from exposure to accidentally released oil droplets and/or 

chemical dispersants are anticipated to be mostly sublethal and recoverable. Sublethal impacts that 

may occur to exposed deepwater benthic organisms may include reduced feeding, reduced 

reproduction and growth, physical tissue damage, and altered behavior. For example, short-term, 

sublethal responses of a shallow-water coral species included mesenterial filament extrusion, 

extreme tissue contraction, tentacle retraction, and localized tissue rupture reported after 24 hours of 

exposure to dispersed oil at a concentration of 20 ppm (Knap et al., 1983; Wyers et al., 1986). 

Laboratory tests by DeLeo et al. (2015) on the relative effects of oil, chemical dispersants, and 

chemically dispersed oil mixtures on three species of northern GOM deepwater corals found much 

greater health declines in response to chemical dispersants and to oil-dispersant mixtures than to 

oil-only treatments, which did not result in mortality. It is important to note that, generally, laboratory 

experimental concentrations are designed to discover toxicity thresholds (as in DeLeo et al., 2015) 

that exceed probable exposure concentrations in the field.
Description of the Affected Environment and Impact Analysis 4-113

Chemosynthetic organisms are naturally adapted to handle the limited amounts of 

hydrocarbons typical of slow-flowing seeps. While they have not been as well studied as deepwater 

corals, there have not been documented impacts from the Deepwater Horizon oil spill to 

chemosynthetic communities (USDOI, BOEM, 2012b; Shedd, official communication, 2015). It is 

possible that some deepwater coral species also have limited capabilities to endure oil exposure. 

Al-Dahash and Mahmoud (2013) suggest that a possible mechanism for this is coral harboring of 

symbiotic oil-degrading bacteria. Results from DeLeo et al. (2015) suggested that Callogorgia delta, 

a soft coral often associated with natural hydrocarbon seeps, may have some natural adaptation to 

short-term oil exposure. Oil spills originating at the surface have fairly limited potential to directly 

impact deepwater benthic communities. Oil becomes diluted as it physically mixes with the 

surrounding water and moves into the water column, and the physical mixing zone of surface oil is 

generally limited to approximately 33 ft (20 m) (Lange, 1985; McAuliffe et al., 1975 and 1981a; 

Tkalich and Chan, 2002; Thompson et al., 1999; Schroeder, 2000). In one extraordinary 

circumstance, a tropical storm forced a large volume of dispersant/oil mixture as deep as 246 ft 

(75 m), causing exposure to mesophotic corals in the Pinnacle Trend area (Silva et al., 2015), but 

that depth is still far shallower than that of the deepwater benthic communities analyzed in this 

chapter.

The USCG may allow the application of chemical dispersants in certain spill situations. 

Chemical dispersion of oil can help to break up concentrations of oil, accelerate natural weathering 

processes, and promote bacterial biodegradation (Chapter 3.2.7). Use of dispersants may, 

however, have unintended effects. For example, it may allow surface oil to penetrate to greater 

depths than expected from normal physical mixing, and dispersed oil more often remains below the 

water’s surface (McAuliffe et al., 1981b; Lewis and Aurand, 1997), possibly leading to negative 

impacts such as those observed by Silva et al. (2015). DeLeo et al. (2015) demonstrated that 

concentrated amounts of dispersant and oil/dispersant mixtures caused more severe health declines 

to deepwater coral than oil-only mixtures.

In a subsurface spill or loss of well control situation, it is expected that the majority of 

released oil would rise quickly to the surface due to the characteristics of northern GOM oil reserves. 

However, if an oil spill occurs at great depths and is subjected to higher water pressures, some oil 

droplets may emulsify and become entrained deep in the water column (Boehm and Fiest, 1982), 

creating a subsurface plume (Adcroft et al., 2010). During the Deepwater Horizon oil spill, 

dispersants were applied subsea at the source of the blowout. Stratified density layers of water 

allowed the oil/dispersant plume to remain at depth instead of dispersing up into the water column 

(Joint Analysis Group, 2010), and these concentrated plumes likely contributed to the serious (but 

localized) damage to deepwater coral communities. If a concentrated plume comes into continuous 

contact with a deepwater benthic community, the general impacts could include mortality, tissue 

loss, opportunistic hydroid overgrowth, failed reproductive success, reduced biodiversity, reduced 

coverage of fauna and flora on hard substrates, and changes in community structure (White et al., 

2012; Hsing et al., 2013; Fisher et al., 2014a; Silva et al., 2015). Exact impacts would depend on 

the location, age of the spill, and the hydrographic characteristics of the area. Adherence to the 

mitigating well-distancing requirements should reduce such impacts.
4-114 Gulf of Mexico Multisale EIS

For any accidental spill (refer to the Catastrophic Spill Events Analysis white paper for larger 

events that are not reasonably foreseeable [USDOI, BOEM, 2016c]), it is expected that a certain 

quantity of oil may eventually settle on the seafloor through a binding process with suspended 

sediment particles (adsorption) or after being consumed and excreted by phytoplankton (Passow 

et al., 2012, Valentine et al., 2014). The product of these processes is sometimes referred to as 

“marine snow.” It is expected that the greatest amount of adsorbed oil particles would occur close to 

the spill, with the concentrations reducing over distance. Adherence to the original well distancing 

requirements should therefore reduce such impacts.

If a spill does occur close to a deepwater benthic habitat, some of the organisms may 

become smothered by marine snow particles and/or other sediments, and experience long-term 

exposure to hydrocarbons and/or oil-dispersant mixtures that could persist within the sediments 

(Hsing et al., 2013; Fisher et al., 2014a; Valentine et al., 2014). White et al. (2014) found the anionic 

surfactant DOSS (dioctyl sodium sulfosuccinate) persisting for at least 6 months within a deepwater 

coral community, although that study did not measure toxicity. Krasnec et al. (2015) did measure 

toxicity of sediments collected within 2 km (1.2 mi) of the Macondo wellhead, but they did not 

measure the effects on deepwater megafauna. The study found varying levels of mortality and 

growth inhibition for a small shrimp-like crustacean species, with the relative degree of toxicity 

decreasing over time (lower toxicity found in 2014 samples than in 2011 samples). Beyond the 

localized area of impact in such cases, particles would become increasingly biodegraded and 

dispersed. Localized impacts to deepwater benthic organisms from marine snow would be expected 

to be mostly sublethal and could include reduced recruitment success, reduced growth, and reduced 

biological cover as a result of impaired recruitment (Rogers, 1990; Kushmaro et al., 1997).

Sediments suspended or displaced as a result of a loss of well control could also impact 

deepwater benthic organisms. These impacts would be largely identical to those caused by 

sedimentation stirred up by bottom-disturbing equipment, with the possible addition of toxic 

hydrocarbons or drilling muds in the sediments (refer to “Routine Activities” above). Because OCSpermitted wells would have been distanced from deepwater benthic habitats before installation, it is 

expected that the heaviest sediment concentrations would fall out of suspension and disperse before 

reaching sensitive benthic communities, preventing most impacts. Some live bottom organisms, 

such as flexible sea fans, are naturally adapted to turbid conditions and may not be as negatively 

affected. Outside of a catastrophic blowout situation, a very substantial amount of sediment burial of 

organisms during an accidental spill event is not reasonably foreseeable (refer to the Catastrophic 

Spill Events Analysis white paper, USDOI, BOEM, 2016c).

Finally, spill cleanup/response activities could themselves have negative impacts (Chapter 

3.2.7). During a response operation, the risk of accidental impacts of bottom-disturbing equipment is 

increased. There could be unplanned emergency anchoring or accidental losses of equipment from 

responding vessels. Response-related equipment such as seafloor-anchored booms may be used 

and could inadvertently contact deepwater habitats and organisms. In addition, drilling muds may be 

pumped into a well to stop a loss of well control. It is possible that during this process some of this 

mud may be forced out of the well and deposited on the seafloor near the well site. If this occurs, 
Description of the Affected Environment and Impact Analysis 4-115

the impacts would be severe for any organisms buried; however, the impact beyond the immediate 

area would be limited and adherence to the original distancing requirements should prevent or 

reduce most impacts.

Accidental spills have historically been small and are low-probability events (Chapters 

3.2.1.4, 3.2.1.5, and 3.2.1.6; Table 3-12). The total amount of deepwater benthic communities is 

small and the habitats are widely distributed, so a localized impact from one noncatastrophic 

accidental event would only impact a small portion of the overall resource.

All of these activities could lead to lethal or sublethal impacts on individual deepwater benthic 

communities, with the range of impacts dependent on the quantity of spilled oil and proximity to 

habitats. While a spill resulting from a catastrophic-level blowout in deep water (such as the 

Deepwater Horizon oil spill) has the potential to seriously impact individual deepwater benthic 

communities over a long time period, such a spill is not reasonably foreseeable as a result of a 

proposed lease sale. Impacts from individual routine activities and reasonably foreseeable 

accidental events are usually temporary, highly localized, and expected to impact only small 

numbers of organisms and substrates at a time. Natural adaptations to small quantities of oil 

(Al-Dahash and Mahmoud, 2013; DeLeo et al., 2015) and/or recovery over time (Hsing et al., 2013) 

is possible for certain deepwater benthic species. Moreover, use of the expected site-specific plan 

reviews/mitigations would distance activities from deepwater benthic communities, greatly 

diminishing the likelihood and severity of potential effects. Therefore, at the scale of this analysis 

and with application of the expected mitigation practices, impacts on deepwater benthic communities 

from accidental spills are expected to range from negligible to minor. This range of potential 

impact levels reflects the relative uncertainty associated with unplanned and potentially uncontrolled 

accidental events. The exact impact would depend on overall frequency and severity of accidental 

spills and whether or not community-level accidental impacts can be clearly distinguished from 

natural variation.

Without the protective mitigations provided by postlease reviews and distancing, the potential 

impacts of accidental spills could rise to moderate or even major levels, in the improbable (but 

theoretically possible) case that a large number of accidental spills were to occur at wells in close 

proximity to a large number of deepwater benthic communities. Even without mitigations, the 

likelihood is very low that a large number of accidental spills would occur in close proximity to the 

relatively rare hard substrate habitats supporting deepwater benthic communities, but this possibility 

cannot be definitively ruled out without knowing both the precise distribution of such spills and 

deepwater benthic communities.

Cumulative Impacts

Cumulative impacts on deepwater benthic communities are of concern because of their very 

slow growth rates, which may increase their vulnerability to disturbance over time (Prouty et al., 

2014). This analysis considers the cumulative impacts on deepwater benthic communities resulting 

from (1) the incremental impacts from future routine and accidental oil- and gas-related operations 
4-116 Gulf of Mexico Multisale EIS

from a proposed lease sale, as well as those resulting from past and future OCS leasing; and 

(2) potential impacts stemming from non-OCS oil- and gas-related factors.

OCS Oil- and Gas-Related Impacts

The Cumulative OCS Oil and Gas Program impacts to deepwater benthic communities 

include the long-term, incremental contribution of the routine and accidental bottom-disturbing 

activities outlined above: (1) bottom-disturbance; (2) sediment and waste discharges; and 

(3) noncatastrophic oil spills (Chapter 3.3.1). As already detailed, these impact-producing factors 

have the potential to damage individual deepwater habitats and disrupt associated benthic 

communities if insufficiently distanced or otherwise mitigated.

Bottom-disturbing activities could result in the physical destruction of benthic habitat and 

organisms or the disturbance of sediments within the environment, resulting in partial or complete 

burial and/or increased turbidity (Chapter 3.3.1.5). Routine and accidental waste discharges could 

be toxic if contacted in undiluted form near the source, but that is generally unlikely.

Oil spills and chemical dispersants are known to have negative, acute effects on deepwater 

benthic organisms such as corals (e.g., DeLeo et al., 2015). The cumulative, long-term effects of 

persistent, low-level exposure to oil are not yet fully understood, although such research is ongoing 

following the Deepwater Horizon oil spill (e.g., White et al., 2014; Baguley et al., 2015). All of these 

activities could lead to lethal or sublethal impacts on individual deepwater benthic communities. 

Although a spill resulting from a catastrophic-level blowout in deep water, such as Deepwater 

Horizon blowout (refer to the Catastrophic Spill Events Analysis white paper, USDOI, BOEM, 

2016c), has the potential to seriously impact individual deepwater benthic communities over a long 

time period (Hsing et al., 2013), the spatial extent of impacts from even such a large spill remains 

relatively limited (Montagna et al., 2013; Fisher et al., 2014b) and the probability of additional 

catastrophic-level spills of that size is low.

Impacts from these individual routine activities and accidental events are usually temporary, 

highly localized, and expected to impact only small numbers of organisms and substrates at a time. 

Recovery over time from such impacts is possible for certain species (e.g., Hsing et al., 2013). 

Moreover, use of the expected site-specific plan reviews/mitigations would distance activities from 

deepwater benthic communities, greatly diminishing potential effects. Therefore, the incremental 

cumulative contribution of OCS oil- and gas-related activities is expected to have only negligible to 

minor impacts.

Non-OCS Oil- and Gas-Related Impacts

The cumulative, long-term impacts on deepwater benthic communities of reasonably 

foreseeable, non-OCS oil- and gas-related anthropogenic activities and shifting baseline 

environmental conditions could be substantial, although they are difficult to quantify, particularly 

when projecting future conditions over the next 50 years. A brief summary analysis is provided here. 

It should be noted that BOEM’s site-specific mitigations are designed to protect deepwater benthic 
Description of the Affected Environment and Impact Analysis 4-117

resources from OCS oil- and gas-related activities within BOEM’s jurisdiction and to mitigate against 

any proposed action’s incremental cumulative impact contribution to the overall OCS and non-OCS 

cumulative impacts.

The primary anthropogenic activities are related to commercial fishing (Chapter 4.10). 

Bottom-tending fishing gear of any type (e.g., trawls, traps, bottom-set longlines, and gillnets) can 

affect deepwater benthic communities by dislodging or crushing organisms attached to the bottom, 

with trawls representing the most serious threat (Hourigan, 2014). Currently, the overall amount of 

fishing effort in very deep waters is spatially and temporally limited and primarily consists of a 

relatively small royal red shrimp fishery and only sporadic reports of golden crab traps (CSA, 2002). 

Therefore, at the present time, commercial fishing impacts on GOM deepwater benthic communities 

are negligible. Should the overall amount of effort or types of gear used change dramatically over 

time, fishing impacts could become considerably greater, perhaps as great as major, although that 

theoretical impact level is highly speculative and dependent on unknown and perhaps improbable 

future changes in fishery practices.

Climate change-related effects have the potential to alter baseline environmental conditions 

in the GOM, including in deep waters. A review of climate change is presented in Chapter 4.2.1 of 

the Five-Year Program EIS (USDOI, BOEM, 2016b). Of primary concern for deepwater benthic 

communities is a projected decline of ocean pH of 0.3-0.5 units over the next century, a shift which 

would significantly alter calcium carbonate saturation states in the ocean (Doney et al., 2009). 

Decreased calcification rates have been observed in numerous shallow-water zooxanthellate corals 

(refer to Hofmann et al., 2010). Similar effects could be expected for deepwater corals such as 

Lophelia pertusa (Lunden et al., 2013; Lunden et al., 2014, Hennige et al., 2015) and for various 

other calcifying organisms in deep water (Thresher et al., 2015) and could make it more difficult for 

deepwater calcifying organisms to form or maintain calcium carbonate-based skeletons or shells. At 

the depths of these communities, little to no effect is expected from potential increases in storm 

frequency and intensity that could be attributed to climate change. However, any such increases 

might exacerbate some other types of bottom-disturbing accidental impacts, such as equipment lost 

overboard or toppling of a platform. The cumulative impact level of future climate change-related 

factors is difficult to accurately estimate with the current level of scientific understanding. Important 

baseline data, such as basic measurements of aragonite saturation horizons, are still in the early 

years of collection and analysis, and the many unknown factors involved make it difficult to 

accurately assign an authoritative impact level for this impact-producing factor at the long-term 

scope of this analysis. At present, the overall impact of climate change-related effects is likely 

negligible. However, over the next 50 years, this impact level could rise to as great as major,

should the most extreme impacts projected as a result of climate change-associated factors come to 

pass. 

Incomplete or Unavailable Information

For decades, BOEM has funded research related to deepwater benthic environments in 

order to further the scientific understanding necessary for informed decisionmaking. However, due 
4-118 Gulf of Mexico Multisale EIS

in part to the inherent difficulty of data collection in deepwater environments, there is (and likely 

always would be) incomplete or unavailable information about deepwater benthic communities. 

BOEM has specifically identified incomplete information for OCS oil- and gas-related impacts related 

to the following: locations of deepwater benthic communities in the GOM; toxicity of oil and 

dispersants to deepwater benthic organisms; long-term effects of the totality of the presence of OCS 

oil- and gas-related infrastructure; long-term effects associated with various climate change-related 

factors; cascading ecological effects and interactions between deepwater benthic communities and 

deepwater fish communities; and long-term impacts from the Deepwater Horizon explosion, oil spill, 

and response (refer to the Catastrophic Spill Events Analysis white paper, USDOI, BOEM, 2016c).

As described above, BOEM’s databases of confirmed deepwater benthic communities and 

3D seismic water-bottom anomalies are used when reviewing deepwater exploration and 

development plans. As part of postlease, site-specific development plans, operators must provide a 

variety of high-resolution survey data such as seismic amplitude, multibeam sonar, and sidescansonar data and interpretations of those data, including assessments about potential habitat for 

sensitive benthic communities. If data are sparse or additional detail is needed, site-specific video or 

photographic surveys can be requested and used to develop appropriate mitigations. While 

extremely helpful, BOEM’s databases and survey data are not comprehensive of all deepwater 

benthic communities. For example, available information may not always be of sufficient resolution 

to identify small areas of scattered hard substrate, such as dead clam shells, that may support small 

patches of deepwater benthic habitat, as discussed by Quattrini et al. (2013).

To help fill data gaps about locations of deepwater benthic communities, BOEM may also be 

able to make use of additional datasets created by other Federal agencies. For example, NOAA’s 

Deep Sea Coral Research and Technology Program and NOAA’s National Centers for Coastal 

Ocean Science have been compiling a database of known observations of deepwater corals and 

sponges (USDOC, NOAA, 2015i). This database of confirmed deepwater coral observations could 

be used as an ancillary information source during site-specific plan reviews. However, even with the 

continued additions of observation records over time, it is unlikely that the majority of deepwater 

coral communities would be directly observed and documented because of the inherent logistical 

difficulties involved in deepwater research and data collection. Past research by NOAA (Kinlan 

et al., 2013) has also included efforts to predictively model suitable habitat for deepwater coral and 

sponges, based on the best available physical/environmental datasets. Future research may 

improve on these efforts and expand to include chemosynthetic communities. New datasets and 

models such as these, once they are complete, scientifically vetted, and publicly available, could 

provide helpful ancillary information to further assist BOEM’s site-specific evaluations.

BOEM will continue to analyze and support the continued collection of the best available 

scientific information related to deepwater benthic communities. However, the best available 

information does not provide all of the data necessary for a complete understanding of these 

communities; knowledge gaps exist. For example, there is incomplete information with respect to 

potential long-term effects resulting from exposure to spilled oil, including potential impacts of a 

catastrophic spill such as the Deepwater Horizon oil spill (refer to the Catastrophic Spill Events 
Description of the Affected Environment and Impact Analysis 4-119

Analysis white paper, USDOI, BOEM, 2016c). Detailed information on these impact-producing 

factors may be relevant to the evaluation of impacts on deepwater benthic communities. However, 

in completing this analysis and in making conclusions, BOEM used the best available science to 

determine the range of reasonably foreseeable impacts, applying accepted scientific methodologies 

to both integrate existing information and extrapolate potential outcomes. Therefore, BOEM has 

determined that the incomplete information is not essential to a reasoned choice among alternatives.

4.4.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

The activities proposed under Alternative A could directly impact deepwater benthic 

communities within the GOM. The primary, reasonably foreseeable impact-producing factors for 

deepwater benthic habitats can be grouped into three main categories: (1) bottom-disturbing 

activities; (2) sediment and waste discharges; and (3) oil spills.

BOEM’s site-specific reviews of permit applications would, through distancing and other 

appropriate mitigations, greatly reduce potential impacts to deepwater benthic communities as a 

result of routine activities and accidental events. At the broad scope of this analysis, and assuming 

adherence to all expected postlease, protective restrictions and mitigations, the routine activities are 

expected to have largely short-term, localized and temporary effects on deepwater benthic 

communities that may not be easily detectable or clearly distinguishable from natural variation. 

Therefore, the impacts of routine activities would be expected to be negligible. Accidental events 

(below the threshold of a catastrophic spill, detailed in the Catastrophic Spill Event Analysis white 

paper [USDOI, BOEM, 2016c]) do have the potential to cause detectable, severe damage to 

individual deepwater benthic communities. However, the number of such events is expected to be 

very small and is not expected to have population-level localized impacts and, therefore, might not 

be clearly distinguishable from natural variation. Therefore, the impacts of accidental events would 

be expected to be negligible to minor. Taken together, at the regional, population-level scope of 

this analysis, overall impacts to deepwater benthic communities from reasonably foreseeable routine 

activities and accidental events are expected to be negligible to minor. 

Proposed and existing OCS oil- and gas-related activities would also contribute incrementally 

to the overall OCS and non-OCS cumulative effects experienced by deepwater benthic communities. 

The OCS oil- and gas-related cumulative impacts are estimated to have negligible to minor

impacts. Non-OCS oil- and gas-related activities such as commercial fishing (currently negligible) 

and shifting baseline environmental conditions related to climate change (currently negligible but 

likely to increase to major over time given current trends) could cause more noticeable impacts on 

deepwater benthic communities over the next 50 years.

4.4.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM would hold a lease sale excluding the available unleased blocks 

in the WPA and would offer all available unleased blocks in the CPA and a portion of the EPA. 

Alternative B would not fundamentally alter the conclusions reached for Alternative A, but it would 
4-120 Gulf of Mexico Multisale EIS

reduce the potential impacts of a proposed lease sale in the available unleased blocks in the WPA. 

The impacts from proposed activities to deepwater benthic communities would remain the same in 

leased portions of the CPA/EPA. Impacts resulting from accidental events should remain relatively 

localized, with the number of features affected being directly proportional to the size of the accident. 

An accident along the CPA/WPA border has the possibility to impact features in either planning area. 

Although the area proposed for leasing in the WPA is relatively smaller than the proposed area of 

the CPA/EPA and would experience less projected OCS oil- and gas-related activity (refer to 

Chapter 3), deepwater benthic communities are found throughout all deep waters of the GOM (refer 

to Figures 4-12 through 4-15 above) and, therefore, the impacts associated with Alternative B 

could still potentially cause some population-level effects.

At the regional, population-level scope of this analysis, the overall impact to deepwater 

benthic communities as a result of the activities proposed under in Alternative B are expected to be 

the same as Alternative A, i.e., negligible to minor, assuming the continuation of expected 

mitigation practices. BOEM’s mitigation practices would reduce potential routine activities, 

accidental events, and OCS oil- and gas-related cumulative impacts of a proposed lease sale under 

Alternative B to the range of negligible to minor. Absent these mitigations, the impacts resulting 

from the routine activities and accidental events of a proposed lease sale could be greater; the 

overall population-level impact could range from negligible to moderate (in a theoretical, if 

improbable, worst-case scenario). This impact level is less than the potential major level impact that 

would be possible (absent mitigations) under Alternatives A and D. This difference is due to the 

greatly reduced area available for new leasing under Alternatives B and C, which would somewhat 

limit the number of potentially affected deepwater benthic communities and increase the likelihood of 

long-term recovery to pre-impact levels. However, it is believed that existing mitigation practices 

would continue to be applied to the proposed activities under Alternatives A-D, reducing the 

expected level of OCS oil- and gas-related impacts.

The incremental cumulative impacts of proposed and existing OCS oil- and gas-related 

activities under Alternative B are considered to add only a negligible to minor contribution to the 

overall cumulative impact, which includes the relatively greater influence of non-OCS oil-and gasrelated cumulative impacts occurring throughout the GOM over the 50-year analysis period.

4.4.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Under Alternative C, BOEM would hold a lease sale excluding the available unleased blocks 

in the CPA/EPA and would offer all available unleased blocks in the WPA. Alternative C would not 

fundamentally alter the conclusions reached for Alternative A, but it would reduce the potential 

impacts of a proposed lease sale in the available unleased block in the CPA/EPA. The impacts from 

the proposed activities to deepwater benthic communities would remain the same in leased portions 

of the WPA. Impacts resulting from accidental events should remain relatively localized, with the 

number of features affected being directly proportional to the size of the accident. An accident along 

the WPA/CPA border has the possibility to impact features in either planning area. Although the 
Description of the Affected Environment and Impact Analysis 4-121

area proposed for leasing in the WPA is relatively smaller than the proposed area of the CPA/EPA 

and would experience less projected OCS oil- and gas-related activity (refer to Chapter 3), 

deepwater benthic communities are found throughout all deep waters of the GOM (refer to Figures 

4-12 through 4-15 above) and, therefore, the impacts associated with Alternative C could still 

potentially cause some population-level effects.

At the regional, population-level scope of this analysis, the overall impact to deepwater 

benthic communities as a result of the activities proposed under Alternative C are expected to be the 

same as Alternative A, i.e., negligible to minor, assuming the continuation of expected mitigation 

practices. BOEM’s mitigation practices would reduce potential impacts as a result of routine 

activities, accidental events, and OCS oil- and gas-related cumulative impacts of a proposed lease 

sale under Alternative C to the range of negligible to minor. Absent these mitigations, the impacts 

as a result of the routine activities and accidental events of a proposed lease sale could be greater; 

the overall population level impact could range from negligible to moderate (in a theoretical, if 

improbable, worst-case scenario). This impact level is less than the potential major level impact that 

would be possible (absent mitigations) under Alternatives A and D. This difference is due to the 

greatly reduced area available for new leasing under Alternatives B and C, which would somewhat 

limit the number of potentially affected deepwater benthic communities and increase the likelihood of 

long-term recovery to pre-impact levels. However, it is believed that existing mitigation practices 

would continue to be applied to the proposed activities under Alternatives A-D, reducing the 

expected level of OCS oil- and gas-related impacts.

The incremental cumulative impacts of proposed and existing OCS oil- and gas-related 

activities under Alternative C are considered to add only a negligible to minor contribution to the 

overall cumulative impact, which includes the relatively greater influence of non-OCS oil-and gasrelated cumulative impacts occurring throughout the GOM over the 50-year analysis period.

4.4.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

The exclusion of any or all of the available unleased blocks subject to the either the 

Topographic Features, Live Bottom (Pinnacle Trend), and/or Blocks South of Baldwin County, 

Alabama, Stipulations (Alternative D) would not alter the above conclusions reached for Alternatives 

A, B, or C. Under Alternative D, BOEM could hold a lease sale excluding the leasing of all blocks 

subject to the Topographic Features and Live Bottom (Pinnacle Trend) Stipulations. This would do 

relatively little to reduce the impacts as a result of the routine activities, accidental events, or 

cumulative impacts to deepwater benthic communities. Deepwater benthic communities are 

generally found in depths greater than 300 m (984 ft), and the vast majority of lease blocks covered 

by the Topographic Features and Live Bottom (Pinnacle Trend) Stipulations are in shallower waters. 

The exclusion of blocks subject to the Blocks South of Baldwin County, Alabama, Stipulation is not 

expected to change the impacts to deepwater benthic communities because of the small number of 

blocks and their distance from these communities. Non-OCS oil- and gas-related activities are also 
4-122 Gulf of Mexico Multisale EIS

The Sargassum cycle is truly 

expansive, encompassing 

most of the western Atlantic

Ocean and the Gulf of Mexico 

with the growth, death, and 

decay of these plant and 

epiphytic communities, which 

may play a substantial role in 

the global carbon cycle.

not expected to decrease under this alternative. At the regional, population-level scope of this 

analysis, the overall impact to deepwater benthic communities as a result of the (mitigated) activities 

proposed under Alternative D are expected to be the same as Alternatives A-C, i.e., negligible to 

minor. 

4.4.2.5 Alternative E—No Action

Under Alternative E, a proposed lease sale would be cancelled. The potential for impacts 

would be none because new impacts to deepwater benthic communities related to a cancelled lease 

sale would be avoided entirely. Continuing impacts to the communities would be limited to existing 

routine activities, accidental events, and cumulative impacts associated with previous OCS lease 

sales and development. BOEM’s current mitigation practices already regulate these activities and 

should continue to limit associated new impacts to the negligible to minor range.

Development of oil and gas would, in all likelihood, be proposed again in a future lease sale; 

in that case, the overall level of OCS oil- and gas-related activity would only be delayed, not 

reduced, at least in the short term.

Ongoing non-OCS oil- and gas-related activities are negligible at present time, but they could 

potentially become greater, even rising to major, should there be future changes in fishing practices 

or worst-case changes in climate change-related environmental conditions.

4.5 SARGASSUM AND ASSOCIATED COMMUNITIES

In the Gulf of Mexico, Sargassum and the organisms that 

reside within or around the matrix of plants are some of the most 

widely distributed and easily recognizable species in the GOM. 

Sargassum occurs across the GOM and is part of a cycle that 

spans most of the Northern Hemisphere of the Atlantic Ocean 

including the Caribbean Sea. As such, Sargassum might be 

potentially vulnerable to the development of OCS resources and it 

is necessary to examine the potential impact-producing factors

and determine the susceptibility to these impacts as they relate to 

a proposed action. The approach of the analysis is to focus on 

the potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., 

exploration, development, and production), accidental events, and cumulative activities (Table 4-7). 

The description of the environment provides a baseline that encompasses all previous and current 

OCS oil- and gas-related and non-OCS oil- and gas-related activities to date.
Description of the Affected Environment and Impact Analysis 4-123

Table 4-7. Sargassum and Associated Communities Impact-Producing Factors.

Sargassum and 

Associated Communities Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Vessel Operations Negligible Negligible Negligible Negligible None

Drilling Operations Negligible Negligible Negligible Negligible None

Accidental Impacts

Drilling Operations Negligible Negligible Negligible Negligible None

Vessel Operations Negligible Negligible Negligible Negligible None

Oil Spill and Cleanup Negligible Negligible Negligible Negligible None

Cumulative Impacts

OCS Oil and Gas Negligible Negligible Negligible Negligible Negligible

Non-OCS Oil and Gas Negligible Negligible Negligible Negligible Negligible

Within this chapter, characteristics unique to Sargassum are discussed along with life 

history. In addition, the roles of Sargassum functioning as a habitat, the species that depend on 

Sargassum, and factors that influence Sargassum are also discussed. During this analysis, many 

potential impact-producing factors were identified; however, only several posed a potential enough 

threat to carry forward to a full analysis. The following impact-producing factors were examined for 

their potential impact to Sargassum: 

• vessel operations (Chapter 3.1.4.4);

• presence of toxins in water column (Chapters 3.1.5.1 and 3.1.5.2);

• sediment deposition on seafloor (Chapters 3.1.3.3.1 and 3.1.3.3.2);

• sediment deposition into water column (Chapter 3.1.3.3.2);

• alteration of water-flow patterns;

• impingement (Chapter 3.1.5.1.6);

• vessels sinking (Chapter 3.2.5);

• marine debris (Chapter 3.1.5.3);

• oil spills (Chapter 3.2.1);

• oil-spill cleanup (Chapter 3.2.7); and

• chemical and drilling-fluid spills (Chapter 3.2.6).

An in-depth analysis of these potential factors determined that, although many may occur 

within the GOM, few occur at an extent that could cause impacts to the population of Sargassum as 

a whole. This includes sediment deposition on the seafloor or in the water column, vessels sinking, 
4-124 Gulf of Mexico Multisale EIS

impingement, marine debris, and alteration of water flow patterns. Additionally, impacts associated 

with the presence of toxins and sediments in the water column from discharges during routine 

operations are managed through the NPDES permitting process or by the MARPOL Annex V Treaty. 

Regulation and enforcement of these laws is conducted by a number of agencies, such as the U.S. 

Environmental Protection Agency, NOAA, and the U.S. Coast Guard. These regulations ensure that 

water quality is maintained at a level that is nontoxic to the organisms in the water where it is being 

discharged and are not addressed in this chapter for Sargassum, but rather are discussed in 

Chapter 4.2 (Water Quality). Additionally, cooling water discharges from vessels are also not 

addressed because, compared with the surface area of the environment, the area that could be 

impacted by vessel discharges is miniscule. Finally, the spatial extent and the transient nature of the 

Sargassum cycle is such that it would take a low-probability catastrophic event larger than the 

Deepwater Horizon oil spill to affect enough Sargassum to result in population-level impacts across 

the GOM for more than a season, which is not reasonably foreseeable as a result of a proposed 

lease sale. Other events like deposition of sediments onto the seafloor do not occur within the same 

section of the water column where Sargassum occurs. As such, only the following impact-producing 

factors were identified as having the potential to impact Sargassum and were carried forward to a full 

analysis:

• vessel operations (Chapter 3.1.4.4; routine only; minus discharges);

• chemical and drilling-fluid spills (Chapter 3.2.6; accidental only);

• oil spills (Chapter 3.2.1; accidental only); and

• oil-spill cleanup (Chapter 3.2.7; accidental only).

To facilitate a discussion on the spatial extent of the Sargassum cycle and to put the impactproducing factors in context, Figure 4-16 depicts how these plants move around the Northern 

Hemisphere. The Sargassum loop system initiates in the Sargasso Sea. Atmospheric conditions 

create wind patterns that push Sargassum south, into the Caribbean Sea where it is pushed west by 

the oceanic and atmospheric currents carrying it into the Gulf of Mexico. There it washes ashore on 

the Gulf Coast or gets swept out the Florida Strait via the Gulf Stream (Gower et al., 2013; Frazier 

et al., 2015). Figure 4-16 represents the spatial extent of many of the species that use Sargassum, 

demonstrating that there is a high degree of connection among the Gulf of Mexico OCS planning 

areas and other oceanic basins and mesoscale oceanic features (e.g., Gulf Stream).
Description of the Affected Environment and Impact Analysis 4-125

Figure 4-16. Sargassum Loop System (adapted from Gower et al., 2013, and Frazier et al., 2015).

Impact-Level Definitions

For this analysis, the following criteria were used to categorize the effects of impactproducing factors:

• Negligible – Impacts to Sargassum and associated communities are 

undetectable or limited in scale to the immediate area of the impact-producing 

factor. This may include mortality of the plants or animals associated with 

Sargassum. Such impacts may result in changes to a local community’s species 

abundance and composition, community structure, and/or ecological functioning, 

but any such changes would be spatially localized, short term in duration, and 

would not alter the overall status of Sargassum or associated communities in the 

GOM.

• Minor – Impacts to Sargassum and associated communities are detectable and 

result in changes beyond the immediate area of the impact-producing factor. 

Such impacts could result in noticeable changes to a local community’s species 

abundance and composition, community structure, and/or ecological functioning, 
4-126 Gulf of Mexico Multisale EIS

but would be spatially localized, short term in duration, and would not alter the 

overall status of Sargassum or associated communities in the GOM.

• Moderate – Impacts to Sargassum and associated communities cause 

substantial, population-level changes in species composition, community 

structure, and/or ecological functioning beyond the immediate area of the impactproducing factor. These impacts would be expected to be spatially extensive and 

may impact communities that rely on Sargassum for transportation of larvae, 

settlement, or food beyond the area of the impact-producing factor. However, 

impacts are expected to be temporary to Sargassum and associated 

communities, and there would be no disruption of the global Sargassum cycle. 

• Major – Impacts to Sargassum and associated communities result in the loss of 

Sargassum over large sections of the GOM. This would result in substantial, 

population-level changes in species composition, community structure, and/or 

ecological functioning for Sargassum and communities that rely on Sargassum

for transportation of larvae, settlement, or food beyond the area of the impactproducing factor. These impacts would be expected to be spatially extensive and 

possibly disrupt the global Sargassum cycle.

4.5.1 Description of the Affected Environment

Plant Characteristics

The pelagic complex in the GOM is comprised of S. natans and S. fluitans (Lee and Moser, 

1998; Stoner, 1983; Littler and Littler, 2000). Both species of macrophytes are hyponeustonic and 

are fully adapted to a pelagic existence (Lee and Moser, 1998). Sargassum is characterized by a 

brushy, highly branched thallus with numerous leaf-like blades and berrylike pneumatocysts 

(Coston-Clements et al., 1991; Lee and Moser, 1998; Littler and Littler, 2000). These air bladders 

contain mostly oxygen and can facilitate buoyancy (Hurka, 1971). Net production in Sargassum also 

exceeds respiration by 1.3 times (Blake and Johnson, 1976), and the population can double in size 

every 3 months (Lapointe, 1986), suggesting that Sargassum may be important in the global carbon 

cycle. Sargassum plants may be up to a few meters in length and may be found floating alone or in 

larger rafts or mats depending on the environmental and physiochemical factors. Reproduction 

typically occurs through fragmentation, and the size, shape, and distribution of Sargassum mats can 

change rapidly depending on currents, wind, and other factors.

Life History

The life history of Sargassum in the GOM is part of a larger cycle that includes the midAtlantic Ocean and the Caribbean Sea (Frazier et al., 2015). This cycle begins in the Sargasso Sea 

where Sargassum remains year round. However, winds and currents move some of this Sargassum

south into the Caribbean Sea and eventually into the GOM via the Yucatan Channel. Once in the 

GOM, it moves into the western area where it uses nutrient inputs from coastal rivers, including the 

Mississippi River, for growth. As Sargassum abundance increases, plants would continue to travel 
Description of the Affected Environment and Impact Analysis 4-127

east during the summer months; however, a large quantity of plants would travel in to the nearshore 

where they would be deposited on coastal beaches. Sargassum deposition on Gulf Coast beaches 

is important because Sargassum facilitates dune stabilization and provides a pathway for nutrient 

and energy transfer from the marine environment to the terrestrial environment (Webster and Linton, 

2013). Eventually the plants moving east would be incorporated into the Gulf Stream where they 

return to the Sargasso Sea (Figure 4-16). Throughout this cycle, plants would continue to grow, die, 

and reproduce. When a plant dies, it can sink to the seafloor, transporting nutrients and resources 

to the seafloor (Coston-Clements et al., 1991; Parr, 1939; Wei et al., 2012). Although the cycle 

continues year round, the rapid growth of Sargassum populations in the western GOM typically 

occurs during the spring/summer of the year (Gower et al., 2006; Gower and King, 2008; Gower and 

King, 2011). Estimates suggest that between 0.6 and 6 million metric tons of Sargassum are 

present annually in the GOM, with an additional 100 million metric tons exported to the Atlantic basin 

(Gower and King, 2008; Gower and King, 2011, Gower et al., 2013). The spatial expanse of this life 

history facilitates the rapid recovery from episodic environmental perturbations because of the 

remote probability that any single event could impact the entire spatial distribution.

Habitat Function

While in the oligotrophic waters of the GOM, Sargassum provides islands of high energy and 

carbon content in an otherwise nutrient and carbon poor environment (Stoner, 1983). Sargassum

mats, comprised of a single or multiple plants in a matrix, support a diverse assemblage of marine 

organisms, including micro- and macro-epiphytes (Carpenter and Cox, 1974; Coston-Clements 

et al., 1991), fungi (Winge, 1923), more than 100 species of invertebrates (Coston-Clements et al., 

1991; Huffard et al., 2014), over 100 species of fish (Dooley, 1972; Stoner, 1983; Huffard et al., 

2014), four species of sea turtles (Carr, 1987a; Manzella et al., 2001), and various marine birds (Lee 

and Moser, 1998). Sargassum serves as nurseries, sanctuaries, and forage grounds for both 

commercially and recreationally exploited species (Adams, 1960; Bortone et al., 1977; Dooley, 1972; 

Wells and Rooker, 2004). Sargassum has also been identified as a critical habitat for the 

loggerhead sea turtle (Caretta caretta) (Federal Register, 2014a). Community composition of 

Sargassum mats vary spatiotemporally depending on the environmental and physiochemical factors 

of the waters where the Sargassum mats reside, resulting in a high degree of biologic diversity in 

species abundance, composition, and life history (Wells and Rooker, 2004).

Sargassum-Dependent Communities

Invertebrates

Epiphytic cyanobacteria contribute to overall production and nutrient recycling within the 

Sargassum complex (Wells and Rooker, 2004). Sargassum is colonized by bacteria, hydroids, and 

bryozoans, providing the base of a food web (Dooley, 1972). Both sessile and motile invertebrates 

are found within the Sargassum community. Epifaunal organisms include colonial hydroids, 

encrusting bryozoans, the polychaete Spirorbis, barnacles, sea spiders, and the tunicate Diplosoma 

(Dooley, 1972; Coston-Clements et al., 1991; Huffard et al., 2014). Older plants can become heavily 

encrusted with these organisms, causing them to sink to the seafloor. Some of the motile fauna 
4-128 Gulf of Mexico Multisale EIS

found within the Sargassum matrix include polychaetes, flatworms, nudibranchs, decapod 

crustaceans, and various molluscs (Parr, 1939; Coston-Clements et al., 1991). Sargassum matrices 

provide a habitat that affords a degree of protection, entrains food, and is an effective method for 

traversing long distances for Sargassum-dependent and Sargassum and associated organisms.

Sea Turtles

Four of the five species of sea turtles found in the GOM (all are listed under the ESA) are 

associated with floating Sargassum (Carr and Meylan, 1980; Carr, 1987a; Coston-Clements et al., 

1991; Schwartz, 1988; Witherington et al., 2012). The hatchlings of loggerhead, green (Chelonia 

mydas), Kemp’s ridley (Lepidochelys kempii), and hawksbill (Eretmochelys imbricata) sea turtles are 

thought to find the Sargassum rafts when actively seeking frontal zones, then utilizing the habitat as 

foraging grounds and protection during their pelagic “lost years” (juvenile years in which turtle 

sightings are scarce) (Carr, 1987a; Coston-Clements et al., 1991; Witherington et al., 2012; Putman 

and Mansfield, 2015). In 2014, the FWS designated critical habitat for the Northwest Atlantic Ocean 

Distinct Population Segment for loggerhead sea turtles in waters including associated Sargassum

habitat and beach habitat of the GOM and along the U.S. Atlantic Coast (Federal Register, 2014a). 

For additional information on sea turtles, refer to Chapter 4.9.2 (Protected Species).

Birds

The presence of Sargassum can also influence local abundance and occurrence of certain 

species of marine birds by concentrating food, as many birds actively feed on or around the mats 

(Lee and Moser, 1998; Moser and Lee, 2012). Birds with over 25 percent of their prey living in 

Sargassum are classified as Sargassum specialists. Specialist species included several species of 

shearwaters, terns, phalaropes, petrels, and gulls (Moser and Lee, 2012). For the birds that rely on 

Sargassum for food, the importance of the Sargassum and associated communities to seabird 

abundance and seasonal distribution is expected to be high (Moser and Lee, 2012). For additional 

information on the importance of Sargassum to birds, refer to Chapter 4.8. 

Fish

The assemblages of fishes using Sargassum as a habitat are highly variable in time and 

space (Huffard et al., 2014). Jacks, pompanos, mackerels, scads, triggerfishes, filefishes, 

seahorses, pipefishes, and frogfishes represent up to 97 percent of the fishes in Sargassum mats 

(Dooley, 1972; Bortone et al., 1977). Some species that are endemic to Sargassum utilize the 

habitat for early life stages as well as adult stages, while other species may rely on the habitat only 

as a source of food, protection, and a method of passive transportation during early life stages 

(Bortone et al., 1977; Wells and Rooker, 2004). The abundance of juvenile fish associated with 

these mats suggests that they serve as an important nursery habitat for numerous species (Dooley, 

1972). By serving as a nursery habitat for pelagic, benthic, and even estuarine species, Sargassum

may have influence on the recruitment success of the fishes using it as habitat. For additional 

information on fish, refer to Chapter 4.7. 
Description of the Affected Environment and Impact Analysis 4-129

4.5.2 Environmental Consequences

Because of the spatial extent of the Sargassum cycle, the community dynamics of 

Sargassum and Sargassum-dependent species are influenced by a myriad of complicated factors. 

Many of these factors are poorly understood due to the size and scope of the Sargassum cycle. For 

example, without any substantial changes in environmental conditions, the biomass of Sargassum 

was 200-fold greater in 2011 than the previous 8-year average (Gower and King, 2011). 

Additionally, comparisons across a 40-year period documented that there were no changes in the 

biodiversity of species, but there was a change in community composition for the Sargassumdependent species found in the Atlantic Ocean (and presumably a pre-cursor to GOM populations). 

However, no specific anthropogenic or environmental factor could be identified as the source of 

change (Huffard et al., 2014). One factor that may influence Sargassum communities is that the 

oceanographic processes that concentrate Sargassum into mats and rafts may also concentrate 

surface pollutants and marine debris (Burns and Teal, 1973; Laffoley et al., 2011; Powers et al., 

2013). This was evident during the Deepwater Horizon explosion, oil spill, and response as many 

Sargassum mats were found immersed in oil with little or no visible living-associated organisms 

(Powers et al., 2013). Additionally, Sargassum may be influenced by many nonpoint sources of 

pollution as pollutants are concentrated, possibly magnifying the environmental impacts of those 

substances (Laffoley et al., 2011).

These communities play an important role to ESA-listed species by providing food, habitat, 

and a method of transportation. BOEM consults on these species with the FWS and NMFS. These 

species include sea turtles and birds; to read about the protected species that use these habitats, 

refer to Chapters 4.9.2 and 4.9.4, respectively.

Routine Activities

Impact-producing factors associated with routine activities for a proposed action that could 

affect Sargassum are limited to impacts from vessel operations and impingement on oil and gas 

structures. However, the impediment of the movement of Sargassum mats is expected to affect 

such a small quantity of algae that impacts would be negligible with no consequences to the overall

Sargassum community.

Vessel Operations

It is expected that a fleet of vessels would be used to support oil and gas exploration, 

production, and possibly other OCS oil- and gas-related operations across the GOM (Chapter 

3.1.4.4). Because of the pelagic life history of Sargassum, vessels supporting oil and gas operations 

would routinely come in contact with Sargassum and associated communities. When impacts occur, 

it would be the result of Sargassum coming in contact with the vessel hull or in contact with the 

propulsion system. The consequence could be the break-up of Sargassum plants into smaller 

pieces, death of Sargassum plants, or dislodging and/or death of epiphytic organisms or organisms 

living in close proximity to Sargassum. However, impacts to Sargassum would only occur if the 

vessel is traveling at a high rate of speed and comes in contact with the plants. If individual plants 
4-130 Gulf of Mexico Multisale EIS

are broken into moderately sized pieces during low-speed travel, it is expected that the plants would 

continue to grow as multiple separate entities through vegetative propagation. For Sargassumdependent organisms that are physically attached to the plant matrix (e.g. epiphytes), dislodgement 

would result in death as they sink to the seafloor or are preyed upon. For animals that live in close 

proximity to Sargassum, it is expected that dislodgement would be temporary as they would find 

their way back to the plant, or other plants, after the vessel had passed. Again, this would only 

occur if contact occurs with the vessel traveling at a rate of speed great enough to actually dislodge 

organisms. This critical speed would be dependent on sea-state, types of organisms present, vessel 

size, and depth of Sargassum in the water column.

Regardless of the possibility of impacts to individual Sargassum plants and associated 

communities, vessel operations are expected to have negligible impacts on the population of 

Sargassum or to the animals that colonize the plants. The primary reason is that the Sargassum 

cycle (refer to “Life History” in Chapter 4.5.1 above) rapidly replaces (days to weeks) any plants that 

are damaged or destroyed by OCS oil- and gas-related vessels in a given area. Vessels would also 

have to be travelling at a high rate of speed and contact Sargassum. Vessels and Sargassum each 

move haphazardly, minimizing the possibility of contact to any particular piece of Sargassum. If 

contact does occur, there are few locations on the vessel (e.g. rudders, intakes) where Sargassum

could actually become impinged. Additionally, the oceanographic processes that cause Sargassum

to form large rafts would also cause large pieces of marine debris (e.g. trees, lumber, and trash) to 

collect with the Sargassum. As such, many vessels would avoid large rafts or slow down as they 

pass through, minimizing potential impacts to Sargassum. Finally, many of the vessels working in 

the OCS oil- and gas-related fields rely on displacement hulls rather than planning hulls. Because of 

this, most vessels would push plants away from the vessel rather than colliding with the plants. 

Damage would be limited to those that pass through the propulsion system of the vessel. Even on 

the largest vessels, the diameter of the propellers is relatively small, resulting in short-term, localized 

damage that should have negligible impacts to the population of Sargassum or the organisms that 

coexist within the plant matrix.

Accidental Events

Impact-producing factors associated with accidental events for a proposed action include 

(1) impacts associated with drilling operations, (2) impacts due to vessel operations, and (3) impacts 

resulting from an oil spill and associated cleanup operations. These impact-producing factors would 

have varied effects depending on the intensity of the spill, the presence of Sargassum, and the 

abundance of Sargassum in the vicinity of the spill.

Drilling Operations

Accidental events associated with drilling operations are limited to the accidental discharge 

of drilling muds and chemicals into the water column (Chapter 3.2.6). This type of event may occur 

if the equipment separating SBFs from the cuttings malfunctions. Although the toxicity of SBFs is 

regulated by the USEPA and are not typically toxic (USEPA, 2004, 2007, and 2009), an unexpected 

release into a Sargassum raft could potentially result in damage to the plants or the organisms that 
Description of the Affected Environment and Impact Analysis 4-131

inhabit Sargassum. Because of the cost of SBFs, the systems responsible for separating SBFs from 

the drill cuttings for reuse are monitored closely; as such, any accidental discharge of SBFs would 

be limited in size and scope. Once in the water column, SBFs would clump and sink quickly and 

impact only the plants and animals that come in contact with the SBFs. Because Sargassum is 

constantly moving horizontally within the environment, the abundance of plants that could be 

impacted by any given accident would be minimal. Due to the cyclical life history of Sargassum, 

dead plants would sink to the seafloor and would rapidly be replaced by new plants moving into the 

area. Although impacts could occur at isolated locations and at a small scale, they would be limited 

in size, scope, and duration, with negligible population-level impacts expected.

Vessel Operations

Although regulated by MARPOL and other regulations, the only reasonably foreseeable 

accidental event associated with vessel operations that may impact Sargassum is the release of 

floating debris into the surface waters of the GOM (Chapters 3.1.5.2 and 3.1.5.3.4). The accidental 

release of marine debris could occur when cargo is not properly restrained on deck while underway 

or during transfer operations between vessels and platforms. Losses of large quantities of debris 

are rare; however, losses of smaller pieces of debris might happen (e.g., trash, safety vests, 

hardhats, etc.). Floating debris is subject to the same oceanographic process that influences and 

moves Sargassum, resulting in marine debris and Sargassum rafting together. Marine debris may 

have little impact on the plants, but the organisms living in close proximity might be impacted. This 

includes the ingestion of plastics by sea turtles, ingestion of microplastics by fishes and 

invertebrates, or the release of toxins from within an object (e.g., a bucket of paint) or as an object 

undergoes degradation, which are discussed in Chapters 4.7 (Fish and Invertebrate Resources) 

and Chapter 4.9.2 (Sea Turtles) (Engler, 2012; Schuyler et al., 2012; Wright et al., 2013). Given the 

lack of stationary gyres in the GOM, OCS oil- and gas-related floating debris would not be expected 

to remain long enough to undergo substantial degradation before washing ashore along a beach or 

sinking to the seafloor. There is a remote possibility that some debris might be advected within the 

Gulf Stream and carried to the gyre in the mid-Atlantic. This debris could remain long enough to 

undergo degradation or be ingested; however, this would be a small enough amount of debris from 

OCS oil- and gas- related activities to have a negligible impact. BOEM and BSEE have addressed 

the marine debris issue by historically imposing marine debris awareness and prevention on the oil 

and gas industry through NTL 2015-BSEE-G03 as a part of the Protected Species Stipulation. 

Overall, vessel operations are expected to have a negligible impact on Sargassum and their 

associated communities because of the minimal volume expected and reduced residency times.

Oil Spills and Associated Cleanup Operations

Oil spills are the major accidental events of concern to the Sargassum community (refer to 

Chapter 3.2.1 for information on oil spills). The risk of various sizes of oil spills occurring as a result 

of a proposed lease sale is presented in Table 3-17. 

All known reserves in the GOM have specific gravity characteristics that indicate the oil 

would float to the sea surface (Chapter 3.2.1.2). Oil on the sea surface has the potential to 
4-132 Gulf of Mexico Multisale EIS

negatively impact Sargassum communities. Some components of oil on the sea surface would be 

removed through evaporation, dissipation, biodegradation, and oil-spill cleanup operations; however, 

depending on the size of the spill, some of them could persist, contacting shore (Chapters 3.2.1.3 

and 3.2.7). Oil at the sea surface can be mixed into the upper water column by wind and wave 

action to a depth of approximately 33 ft (10 m) (Lange, 1985; McAuliffe et al., 1975 and 1981b; Knap 

et al., 1985). With vigorous wave action, the oil can form an emulsion with water that is viscous and 

persistent. Oil treated with dispersant on the sea surface would mix with the water where its contact 

with Sargassum may be temporarily increased in the upper few meters of the water column 

(McAuliffe et al., 1981a). As time passes, the oil would begin to adhere to particles in the water 

column, form clumps, and sink toward the seafloor (International Tanker Owners Pollution 

Federation Limited, 2002; Kingston et al., 1995; Powers et al., 2013).

The impacts of oil contact with Sargassum communities would vary depending on the 

severity of exposure. Sargassum that contacts concentrated oil that coats the algae and attached 

organisms would likely die and sink to the seafloor (Powers et al., 2013). Motile organisms that are 

dependent on the algae for habitat (e.g., shrimp, crabs, nudibranchs, snails, Sargassum fish, etc.) 

may also be directly contacted by the oil, resulting in death, or may be displaced into open water. 

Sargassum exposed to oil in lower concentrations may suffer sublethal impacts and concentrate 

hydrocarbons, toxins, and chemicals (Burns and Teal, 1973). Exposure to these low-level toxins 

could result in the loss of associated organisms that use the algae as a substrate and other 

organisms that use the matrix as habitat due to the presence of bacterial-mediated hypoxic 

conditions in the immediate vicinity of the plant as the oil is consumed (Powers et al., 2013). 

However, hypoxia would be naturally mitigated due to wave action. Pelagic organisms feeding on or 

around the community may suffer sublethal effects that could reduce health and reproduction-like 

reduced growth or fecundity. For information on fauna that are part of the Sargassum community, 

refer to Chapters 4.7 (Fish and Invertebrate Resources), 4.8 (Birds), 4.9.2 (Sea Turtles), and 4.9.4

(Protected Birds).

Spill-response activities may contribute to negative impacts on Sargassum (refer to Chapter 

3.2.7 for information on oil-spill response activities). The number of vessels concentrated in a given 

area to clean up a spill can increase physical damage to the Sargassum community, especially in 

the immediate vicinity of the spill. Response activities, such as skimming oil from the sea surface or 

burning oil at the surface, can damage and remove Sargassum that may not have contacted oil. 

However, for oil-coated Sargassum, these impacts may be inconsequential, as a large part of the 

Sargassum affected would not be expected to survive (Powers et al., 2013). Another major 

response activity that may occur is the spraying of dispersant. Direct effects of dispersant on many 

of the more mobile constituents of the Sargassum community are limited, but dispersants are toxic to 

Sargassum plants and many invertebrates (Powers et al., 2013; Almeda et al., 2014). The use of 

dispersants is a trade-off to achieve the least overall environmental damage. For example, 

dispersants may increase short-term contact of oil with Sargassum and may have some inherent 

toxic properties, but their use can prevent the formation of persistent emulsions and promote 

diffusion of oil, resulting in biodegradation, clumping, and sinking.
Description of the Affected Environment and Impact Analysis 4-133

A spill may impact the survivability and productivity of Sargassum in an area (Powers et al., 

2013). However, an accidental spill would only be expected to have an impact in the immediate 

area and would be short in duration. Given the life history of Sargassum, it is expected that, for an 

accidental spill, fresh plants would replace the old plant within days to weeks. The new plants would 

also provide habitat for any organisms with the desire to leave impacted plants, which could happen 

in the natural life cycle of Sargassum. The Sargassum community is widely distributed over a very 

large area, including two oceans, and appears to have an annual cycle of growth that lends itself to 

resilient recovery in a short time. Due to the spatial extent of the Sargassum cycle, impacts due to 

an accidental oil spill are expected to be negligible to the Sargassum population; however, in the 

immediate area of a spill, the short-term impacts could range from moderate to major depending 

directly on the size of the spill and amount of Sargassum in the area.

Cumulative Impacts

Several impact-producing factors can affect Sargassum, including vessel-related operations, 

oil and gas drilling discharges, operational discharges, accidental spills, non-OCS oil- and gasrelated vessel activity, and coastal water quality.

OCS Oil- and Gas-Related Impacts

Vessels transiting the GOM pass through Sargassum mats, producing slight impacts to the 

Sargassum community by their passage, some propeller impacts, and possible impingement 

impacts (refer to Chapter 3.3.1.7 for information on cumulative service-vessel numbers). None of 

these would have more than minor localized impacts to the mats, but they could lead to the loss of 

plants or stress for organisms. The OCS oil- and gas-related structures can impede the movement 

of Sargassum mats and may entrap small quantities of the algae. This is expected to have a 

negligible impact with no consequences to the overall Sargassum community.

The OCS oil- and gas-related drilling results in discharges of drill cuttings with small 

quantities of associated drilling muds and well treatment chemicals. Most cuttings from well drilling 

are discharged from the drill platform at the sea surface where they disperse (CSA, 2006; Kennicutt 

et al., 1996; NRC, 1983). Floating mats of Sargassum that pass by a drilling operation would 

experience short-term exposure to drill cuttings with associated muds and well treatment chemicals. 

Discharges are regulated and tested by the USEPA to ensure that discharges released into the 

environment are nontoxic or not concentrated enough to become toxic (USEPA, 2004, 2007, and 

2009b). Drilling operations create an area of high turbidity in the vicinity of drilling operations where 

cuttings are discharged. Impacts from sedimentation to the community 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).

The OCS oil- and gas-related platforms and drill ships produce similar effects with 

operational discharges. Larger vessels and offshore platforms discharge effluents from sanitary 
4-134 Gulf of Mexico Multisale EIS

facilities (gray water) and circulate seawater to cool ships’ engines, electric generators, and other 

machines. The cooling water discharge may be up to 20 o

F (11 oC) warmer than the surrounding 

seawater (USDHS, CG and USDOT, MARAD, 2003; Patrick et al., 1993). This temperature 

difference can accumulate in the vicinity of the discharge. For OCS oil- and gas-related stationary 

platforms and drill ships, localized warming of the water could occur (Emery et al., 1997; USDHS, 

CG, and USDOT, MARAD, 2003). However, the warm water is rapidly diluted, mixing to background 

temperature levels within 328 ft (100 m) of the source (USDHS, CG and USDOT, MARAD, 2003). 

Additionally, produced waters from stationary locations are rapidly diluted, and impacts are only 

observed within 328 ft (100 m) of the discharge point (Neff and Sauer, 1991; Trefry et al., 1995; 

Gittings et al., 1992b). Those effects are localized, with only brief contact to passing Sargassum

before dilution to background levels; however, this could result in discomfort, displacement, or death 

to some of the more sensitive organisms. These effects would comprise a negligible portion of the 

overall cumulative impact to Sargassum communities.

Accidental spills of oil and other chemicals could affect Sargassum and its community 

wherever they contact the algae. Small spills would have a limited local effect on a small portion of 

the Sargassum community. Short-term exposure of passing Sargassum to high concentrations of oil 

and chemicals could result in death and sinking of the algae and organisms contacted. The size of 

the overall impact on Sargassum would depend on the size of the spill and the success of spillresponse efforts; therefore, impacts from an accidental release of oil could range from negligible to 

moderate. Impacts would not affect the population, but substantial impacts could be expected to the 

organisms exposed, although limited in spatial extent and duration. This includes death if oil 

concentrations in the water column are great enough to result in ingestion of oil or coating of the 

organisms residing in the vicinity of Sargassum mats (Fucik et al., 1995; Brewton et al., 2013).

Non-OCS Oil- and Gas-Related Impacts

Marine vessels of all types produce at least some minor effects to the environment (refer to 

Chapter 3.3.2.2). Increased abundance of non-OCS oil- and gas-related vessels operating in the 

same environment as Sargassum presents an increase in the expected vessel-related damage to 

Sargassum and associated communities. Given that most vessels are limited to the waters 

nearshore (e.g., recreational fishermen), the impacts on Sargassum is expected to be minor. 

Sargassum found in near-coastal waters is expected to eventually senesce (the process of aging in 

plants) and sink to the seafloor or be deposited on coastal beaches. As such, additional damage to 

any Sargassum that may occur would not impact the population. Offshore traffic would be limited 

and occur in a haphazard manner beyond shipping lanes. As such, the movement of Sargassum

combined with the movement of vessels ensures that no impacts occur routinely to any given 

Sargassum, resulting in negligible cumulative impacts by non-OCS oil- and gas-related vessel 

traffic.

Declining coastal water conditions, due to eutrophication, are a non-OCS oil- and gas-related 

impact that could result in landscape level impacts to Sargassum (Chapter 3.3.2.11). Increased 

nutrient loading can lead to increased turbidity from plankton growth and a reduction in oxygen 
Description of the Affected Environment and Impact Analysis 4-135

during periods of hypoxia (e.g., in the summer; refer to Chapter 3.3.2.12). Turbidity could result in a 

decrease in Sargassum production and result in stress to the organisms inhabiting these habitats, 

while increased nutrients could result in an increased growth of Sargassum. A reduction in 

production could result in a decrease in the ability of Sargassum to sequester nutrients and carbon 

dioxide and to produce oxygen, while an increase in production could provide more habitat. The 

exact impact of declining water quality is unknown because Sargassum can pass in and out of these 

waters depending on the prevailing conditions, and much of the more hypoxic and highly turbid 

waters occur nearshore where Sargassum would not normally survive because it would be 

deposited on a coastal beach or senesce (the process of aging in plants) and sink to the seafloor.

Combined, the cumulative impacts of OCS oil- and gas-related operations would be 

negligible to the population, but there may be localized impacts to a small portion of the total 

Sargassum population. Because the Sargassum cycle occurs across a large portion of the Western 

Hemisphere (Frazier et al., 2015) and because OCS oil- and gas-related operations rarely occur in 

dense aggregations, especially with respect to drilling operations, the cumulative impacts of a 

proposed action on the population of Sargassum would be negligible. The impacts of OCS oil- and 

gas-related operations, combined with non-OCS oil- and gas-related factors would not result in an 

increase in the overall impact of oil and gas operations resulting from a proposed action. Non-OCS 

oil- and gas-related vessel traffic is not expected to have a substantial impact on Sargassum and 

associated communities; however, declining coastal water quality as a result of eutrophication could, 

as described in Chapter 4.2 (Water Quality). Regardless, the incremental impact of OCS oil- and 

gas-related operations on the population of Sargassum would be negligible and not result in 

cumulative impacts to the population. Impacts from changing water quality would be much more 

influential on Sargassum than OCS development and would still occur without the presence of OCS 

oil- and gas-related operations.

Incomplete or Unavailable Information

Although much is known about Sargassum and its life history, incomplete or unavailable 

information still remains. This incomplete or unavailable information includes information on the 

effects of in situ oil exposure and the factors impacting the movement patterns of Sargassum. 

BOEM used existing information and reasonably accepted scientific methodologies to extrapolate in 

completing the analysis above. BOEM has determined that there are few foreseeable significant 

adverse impacts to the Sargassum population associated with OCS oil- and gas-related routine 

activities or accidental events, using publications such as Frazier et al. (2015), 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. Frazier et al. (2015) built upon these studies and 

developed a more finite life cycle for Sargassum that links the Sargasso Sea Sargassum populations 

with the GOM populations. With respect to the effects of oiling, 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. 
4-136 Gulf of Mexico Multisale EIS

Additionally, Lindo-Atichati et al. (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 any given 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 

impacts to Sargassum due to contact with oil and dispersants under the proper conditions, but the 

spatial or temporal extent of those impacts remain unknown. It is expected that, for routine activities 

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 ephemeral and wide-ranging nature across the northern GOM 

and the reproductive capabilities of Sargassum provide a life history that is resilient towards 

localized or short-term deleterious impacts, such as those expected to be associated with OCS oiland gas-related routine activities and noncatastrophic oil or SBF spills. Therefore, BOEM has 

determined that the incomplete information on Sargassum is not essential to a reasoned choice 

among alternatives and that the information used in lieu of the unavailable information is acceptable 

for this analysis.

4.5.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Sargassum, as pelagic algae, is a widely distributed resource that is ubiquitous throughout 

the northern GOM and northwest Atlantic. Sargassum has a yearly cycle that promotes quick 

recovery from impacts. Therefore, most routine and accidental impact-producing factors would be 

expected to result in negligible impacts because they only impact a small percentage of the 

population and be limited in size and scope as new plants rapidly replace the impacted plants. In 

addition, the cumulative impact on Sargassum and associated communities for Alternative A would 

be negligible, as all expected impacts are from non-OCS oil- and gas-related activities and are 

mutually exclusive from any impacts resulting from a proposed action and previous OCS oil- and 

gas-related actions. Because the impacts of routine activities, accidental event, and cumulative 

impacts are negligible, the overall impacts to Sargassum and associated communities are expected 

to be negligible. 

4.5.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area 

Under this Alternative, impacts to Sargassum and associated communities would be 

eliminated in the WPA area. This would exclude those impacts from vessels docking in the WPA 

and operating in the CPA or EPA and the cumulative impacts associated with previous OCS oil- and 

gas-related development and non-OCS oil- and gas-related activities. Any spill-related impacts 

would be limited to the areas along the WPA/CPA boundary and would not impact Sargassum

communities beyond the area of the spill. While the CPA/EPA has this greatest potential for OCS oil

and gas-related activity, Sargassum is common throughout the area and it routinely moves across 

the Gulf. As such, any localized impacts would be short-term as plants are replaced, resulting in no 
Description of the Affected Environment and Impact Analysis 4-137

population-level impacts, and therefore, impact conclusions do not differ from Alternative A, which 

are negligible.

4.5.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Under this Alternative, impacts to Sargassum and associated communities would be 

eliminated in the CPA/EPA area. This would exclude those impacts from vessels docking in the 

CPA and operating in the WPA and the cumulative impacts associated with previous OCS oil- and 

gas-related development and non-OCS oil- and gas-related activities. Any spill-related impacts 

would be limited to the areas along the WPA/CPA boundary and would not impact Sargassum

communities beyond the scope of the spill. While the WPA is a smaller area with less projected 

activity than is proposed for the CPA/EPA (refer to Chapter 3), Sargassum is common throughout 

the area and it routinely moves across the Gulf. As such, any localized impacts would be short-term 

as plants are replaced, resulting in no population-level impacts, and therefore, impact conclusions do 

not differ from Alternative A, which are negligible.

4.5.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Under this Alternative, impacts to Sargassum would be similar to those described in 

Alternative A, which are negligible. Sargassum moves in the Gulf of Mexico over great spatial 

scales and it would be expected to move in and out of the unleased blocks depending on prevailing 

meteorological processes. In addition, many of these blocks already have OCS oil- and gas-related 

development, and Sargassum would continue to be impacted by the impacts of routine activities and 

accidental events from pre-existing OCS oil- and gas-related development.

4.5.2.5 Alternative E—No Action

Under Alternative E, a proposed lease sale would be cancelled and the potential for impacts 

from routine activities and accidental events would be none. Under this Alternative, impacts to 

Sargassum would be limited to cumulative impacts associated with previous OCS oil- and gasrelated development and non-OCS oil- and gas-related activities. Sargassum moves in the Gulf of 

Mexico over great spatial scales and it would be expected to move in and out of the previously 

leased blocks depending on prevailing meteorological processes. In addition, many of these blocks 

already have OCS oil- and gas-related development, and Sargassum would continue to be impacted 

by the impacts of routine activities and accidental events from pre-existing OCS oil- and gas-related 

development.

4.6 LIVE BOTTOM HABITATS

This chapter describes shallow-water hard/live bottom habitats in Gulf of Mexico OCS 

planning areas. Hard bottoms are naturally occurring, rocky, consolidated substrates that are 

geological (e.g., exposed sedimentary bedrock) or biogenic (e.g., carbonate relic coral reef) in origin. 
4-138 Gulf of Mexico Multisale EIS

These habitats occur throughout the GOM but are relatively rare compared with the soft bottoms that 

are ubiquitous throughout most of the GOM. Hard bottoms, particularly those having measurable 

vertical relief, can serve as important habitat for a wide variety of marine organisms. Encrusting 

algae and sessile invertebrates such as corals, sponges, sea fans, sea whips, hydroids, anemones, 

ascidians, and bryozoans may attach to and cover hard substrates, thereby creating “live bottoms,” a 

term first coined by Cummins et al. (1962). The attached flora and fauna of live bottoms, such as 

large sponges and structure-forming corals, further enhance the structural complexity of the benthic 

environment. Complex structure offers shelter that can be attractive to smaller invertebrates and 

fishes (Fraser and Sedberry, 2008), which, in turn, can provide food for a variety of larger fishes, 

including some commercially important fisheries (Szedlmayer and Lee, 2004; Gallaway et al., 2009). 

Refer to Chapter 4.7 (Fishes and Invertebrate Resources) and the Essential Fish Habitat 

Assessment white paper (USDOI, BOEM, 2016d) for more detail. Seagrasses can also be 

considered a type of live bottom, but they have very different physical characteristics and species 

assemblages than the above and are thus analyzed separately in Chapter 4.3.1. 

Defined topographic features (Chapter 4.6.1) are a subset of GOM live bottom habitats that 

are large enough to have an especially important ecological role, with specific protections defined in 

the Topographic Features Stipulation. The Live Bottom (Pinnacle Trend) Stipulation (Appendix D) 

has historically been applied to specific lease blocks in the CPA and EPA (Figure 4-17) with the 

highest known concentrations of other live bottom features. These features are much smaller in size 

than the topographic features. Live bottom habitats found outside these stipulation lease blocks are 

not specifically included in the stipulation but are still given site-specific protections by BOEM during 

site-specific plan reviews. In Figure 4-17, the smaller black polygons represent the 38 named 

topographic features; selected fishery management areas on the West Florida Shelf, with known 

high concentrations of live bottoms, are shown in gray. The GOM live bottoms are not limited to the 

features/areas shown in Figure 4-17. 

Figure 4-17. Lease Blocks Subject to the Topographic Features and Live Bottom 

(Pinnacle Trend) Stipulations.
Description of the Affected Environment and Impact Analysis 4-139

4.6.1 Topographic Features

In the Gulf of Mexico, geologic features are known to function as hard substrate habitats that 

enable settlement of sensitive benthic organisms, concentrate fishes, and contribute substantially to 

the ecology of the GOM. Known as topographic features, many of these features have been 

identified by stakeholders as locations of value that may require a greater degree of protection from 

OCS development. As such, beginning in 1973, BOEM’s predecessor agency established and 

implemented a Topographic Features Stipulation that OCS operators must respect when working 

around these features. This stipulation has been applied historically in the GOM and establishes a 

No Activity Zone for each feature where no bottom-disturbing activities are allowed and, in most 

cases, establishes additional areas around the No Activity Zones where shunting of drill cuttings and 

drilling fluids is required. This stipulation protects resources by distancing any OCS oil- and gasrelated activity away from topographic features to minimize the impacts of routine activities or 

accidental events. In addition, BOEM enforces a 500-ft (152-m) buffer around each of the No 

Activity Zones where activity is generally not permitted. This policy was developed in consultation 

with NOAA to further protect areas of topographic features not protected by the No Activity Zone. 

Beyond the No Activity Zone, restrictions are placed on how drilling operations discharge cuttings at 

distances of up to 4 mi (6 km) away. These requirements are designed to allow oil to rise to the 

surface prior to contacting a topographic feature or for waterborne substances resulting from OCS 

oil- and gas-related operations to dilute and disperse. It is expected that this stipulation would

continue to be a requirement for OCS operators throughout the entire time period covered by this 

analysis (2017-2022).

To facilitate the understanding of the ecology of topographic features, Figure 4-18 is 

included to present a generalized ecological description of the habitats present at different depths. 

Each of the labels represents different ecological zones common to topographic features; however, 

rarely do all the zones occur on a single feature. For example, the East Flower Garden Bank is 

comprised of all but one ecotone, the Millepora-Sponge Zone. This zone occupies depths 

comparable to the Diploria-Montastraea-Porites Zone on the claystone-siltstone substrate of the 

Texas-Louisiana midshelf banks. Crusts of hydrozoan corals (Millepora alcicornis), sponges, and 

other epifauna typically occupy the tops of outcrops in this zone, but Scleractinian corals and 

coralline algae are rare (Rezak et al., 1990). In addition, for this analysis, the description of the 

resource includes the baseline environment, including the cumulative impacts from all previous OCS 

oil- and gas-related operations on the resource.
4-140 Gulf of Mexico Multisale EIS

Figure 4-18. Ecological Representation of Common Features on Topographic Features in the Gulf 

of Mexico.

Because of the similarity and overlap of the effects of many activities that occur in the OCS, 

all possible impact-producing factors considered can be divided into three broad categories: drilling 

and exploration operations; vessel operations; and oil spill and associated cleanup activities. The 

impact-producing factors evaluated for this resource are listed below.

• Drilling, Exploration, and Decommissioning

− Bottom-disturbing activities (Chapter 3.1.3.3.1) 

− Chemical and drilling-fluid spills (Chapter 3.1.5) 

− Deposition of sediments onto the seafloor (Chapter 3.1.3.3.2) 

• Vessel Operation

− Bottom-disturbing activities (Chapter 3.1.3.3.1) 

− Loss of debris
Description of the Affected Environment and Impact Analysis 4-141

• Oil Spill and Associated Cleanup

− Large and small spills resulting from surface or subsea sources

− Cleanup operations not related to vessel operation

− Sediment burial

An in-depth analysis of these potential factors determined that, although many may occur 

within the GOM, few are at an extent that could cause impacts to the topographic features as a 

whole (Table 4-8) because these habitats are spread across the GOM. 

Table 4-8. Topographic Features Impact-Producing Factors.

Topographic 

Features Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Drilling, Exploration, and Decommissioning 

Bottom-Disturbing Activities

Without Mitigation Moderate Moderate Moderate Negligible None

With Mitigation Negligible Negligible Negligible Negligible N/A

Vessel Operations 

Bottom-Disturbing Activities

Without Mitigation Moderate Moderate Moderate Negligible None

With Mitigation Negligible Negligible Negligible Negligible N/A

Accidental Impacts

Drilling, Exploration, and Decommissioning

Bottom-Disturbing Activities

Without Mitigation Moderate Moderate Moderate Negligible None

With Mitigation Negligible Negligible Negligible Negligible N/A

Chemical and Drilling-Fluid Spills

Without Mitigation Moderate Moderate Moderate Negligible None

With Mitigation Negligible Negligible Negligible Negligible N/A

Vessel Operations 

Bottom-Disturbing Activities

Without Mitigation Moderate Moderate Moderate Negligible None

With Mitigation Negligible Negligible Negligible Negligible N/A

Oil Spills and Associated Cleanup Activities

Large and Small Spills Resulting from Surface or Subsea Sources

Without Mitigation Moderate Moderate Moderate Negligible None

With Mitigation Negligible Negligible Negligible Negligible N/A
4-142 Gulf of Mexico Multisale EIS

Topographic 

Features Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Cleanup Operations Not Related to Vessel Operation

Without Mitigation Moderate Moderate Moderate Negligible None

With Mitigation Negligible Negligible Negligible Negligible N/A

Cumulative Impacts

OCS Oil and Gas

Without Mitigation Moderate Moderate Moderate Moderate Moderate

With Mitigation Negligible to Negligible to Negligible to Negligible to N/A

Minor Minor Minor Minor

Non-OCS Oil and Gas

Without Mitigation Negligible to Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate Moderate

With Mitigation Negligible to Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate Moderate

N/A = not applicable.

The impact-producing factors related to the release of toxins and sediments were not carried 

forward because impacts associated with the presence of toxins and sediments in the water column 

from discharges during routine operations are managed through the NPDES permitting process or 

MARPOL Annex V Treaty. Regulation and enforcement of these laws is conducted by a number of 

agencies, such as the U.S. Environmental Protection Agency, NOAA, and the U.S. Coast Guard. 

These regulations ensure that water quality is maintained at a level that is nontoxic to the organisms 

in the water where it is being discharged and are not addressed in this evaluation. Similarly, the 

release of any debris is also regulated by the USCG and MARPOL and is strictly prohibited; this is 

reinforced by NTL 2015-BSEE-G03, which imposes marine debris awareness and prevention 

measures on the oil and gas industry. Historically, NTL 2015-BSEE-G03 has been made a binding 

part of leases through the Protected Species Stipulation. As such, accumulations of debris at a level 

great enough to impact a topographic feature is unlikely. Additionally, impact-producing factors not 

carried forward include impacts resulting from a vessel sinking and coming to rest on a topographic 

feature. An OCS vessel sinking is a rare event and it is not reasonably expected that a vessel 

sinking on the OCS would come to rest on a topographic feature. Also, sediment burial and surface 

response operations that would occur during an oil spill are impact-producing factors not carried 

forward. Surface cleaning operations may occur in the surface water above a topographic feature; 

however, none of the technologies employed to remove oil at the surface operate at a depth deep 

enough to impact a topographic feature. An accidental burial of organisms by sediment during a spill 

was also not carried forward because it is not reasonably foreseeable that this type of event would 

occur in a noncatastrophic setting. A review of BSEE’s records show that an accidental burial event 

has not occurred since at least 2006, which was when reporting requirements changed to require 

reporting of this type of event (USDOI, BSEE, 2015e). As such, the following impact-producing 

factors were carried forward to a full analysis for routine activities and accidental events:
Description of the Affected Environment and Impact Analysis 4-143

• Routine activities

− Drilling, exploration, and decommissioning

 Bottom-disturbing activities 

− Vessel operation

 Bottom-disturbing activities

• Accidental events

− Drilling, exploration, and decommissioning

 Bottom-disturbing activities 

 Chemical and drilling-fluid spills 

− Vessel operation

 Bottom-disturbing activities 

− Oil spill and associated cleanup

 Large and small spills resulting from surface or subsea sources 

 Cleanup operations not related to vessel operations

Impact-Level Definitions 

For this analysis, the following definitions were used to categorize impacts to topographic 

features:

• Negligible – Impacts to topographic feature communities are largely 

undetectable. There is some potential for even undetectable impacts to cause 

slight changes to a local community’s species abundance and composition, 

community structure, and/or ecological functioning, but any such changes would 

be spatially localized, short term in duration, and would not impact other 

topographic features.

• Minor – Impacts to topographic feature communities are detectable but cannot 

be distinguished from natural variation. Such impacts could result in noticeable 

changes to a local community’s species abundance and composition, community 

structure, and/or ecological functioning, but would be spatially localized, short 

term in duration, and recovery would be expected.

• Moderate – Impacts to topographic feature communities that result in 

substantial, population-level changes in species composition, community 

structure, and/or ecological functioning. These impacts would be expected to be 

spatially extensive, spanning across several topographic features, but impacts 

are expected to result in temporary changes and recovery would be likely.
4-144 Gulf of Mexico Multisale EIS

• Major – Impacts to topographic feature communities that result in substantial, 

population-level changes in species composition, community structure, and/or 

ecological functioning. These impacts would be expected to be spatially 

extensive and noticeably alter the overall status of many topographic features in 

the GOM. Long-term recovery to pre-impact community structure, species 

abundance, or ecological function is unlikely.

4.6.1.1 Description of the Affected Environment

BOEM defines topographic features as a subset of hard bottom habitats found in the GOM 

that are large enough to have a particularly important role in the GOM ecosystem. Although large in 

size, these features are relatively rare compared with the expansive soft bottoms in the central and 

western GOM (Parker et al., 1983). Topographic features can be created by rock uplifted by salt 

diapirs, by relic carbonate reefs, or by the exposure of fossilized barrier islands (Rezak and Bright, 

1981a and 1981b; Berryhill et al., 1987). Regardless of origin, these subsea banks provide areas of 

hard substrate that support benthic and fish communities with relatively high biomass, high diversity, 

and high abundance of plants and animals. Within the context of the larger Gulf ecosystem, these 

features also provide shelter, food, and nursery grounds that support large numbers of commercially 

and recreationally important fishes (Johnston et al., 2015; Nash et al., 2013). Finally, many of these 

habitats remain relatively pristine and have a high aesthetic and scientific value because they 

represent ecologic extremes for many species (Rezak and Bright, 1981a; Nash et al., 2013; 

Johnston et al., 2015).

Within the GOM, BOEM has identified 38 topographic features where some degree of 

protection from oil and gas development is historically warranted based on the geography and 

ecology (Rezak and Bright, 1981a; Rezak et al., 1983). If adopted, 22 protected banks are in the 

WPA, 16 are in the CPA, and 0 are in the EPA (Figure 4-17). For previous lease sales, all banks 

had at least a No Activity Zone where bottom-disturbing activities during oil and gas development 

are prohibited. Most banks have had restrictions beyond the No Activity Zone regulating drilling 

discharges. The No Activity Zones have been defined by BOEM’s policy and are based on a 

specific depth contour. They are designed to protect the most sensitive area of the features. In 

addition, based on EFH programmatic consultation with NMFS, NTL 2009-G39 recommends that 

drilling should not occur within 152 m (500 ft) of a No Activity Zone of a topographic feature. Any 

bottom-disturbing activities within the buffer would require project-specific EFH consultation with 

NMFS.

Topographic features in the GOM span a range of environmental conditions, resulting in a 

wide range of community types. This includes a range from the highly productive hermatypic (i.e., 

reef building) corals found at the Flower Garden Banks to habitats like Dunn Bar that have less 

productive and less diverse benthic habitats but are known to concentrate fishes (Rezak and Bright, 

1981b; Nash et al., 2013).
Description of the Affected Environment and Impact Analysis 4-145

Bank Classification

Shelf-Edge Banks

The shelf-edge banks generally exhibit the greatest range of habitat types of all the 

topographic features because they have the greatest relief (Rezak et al., 1983). The habitats of 

topographic features can be classified into seven categories, and all habitat types can be found on 

the shelf-edge banks, although not all on the same bank (Rezak et al., 1983) (Figure 4-18). These 

habitats range from the reef-building corals, the most complex and diverse of the habitat types, to 

the highly turbid nepheloid layer habitats that have substantially less diversity and production due to 

the presence of high levels of suspended sediments. In general, banks that have the greatest 

vertical relief also have the greatest number of habitat categories present. Light penetration, depth, 

and sediment loading are the most influential environmental parameters to communities colonizing 

topographic features (Rezak et al., 1983). There is a direct relationship between light levels at depth 

and the biodiversity of these habitats.

Among the shelf-edge banks, the Flower Garden Banks and McGrail Bank have been 

identified as exceptionally important components of the GOM ecosystem because these banks 

represent the northern-most colonies of hermatypic corals and may provide larvae/recruits for other 

reefs at great distances away (Goodbody-Gringley et al., 2012). Shelf-edge banks also host 

seasonal feeding and mating, and serve as nursery grounds for many species like manta and devil 

rays, whale sharks, and hammerhead sharks (Burks et al., 2006; Johnston et al., 2015; USDOC, 

NOAA, 2010c; Johnston et al.; 2013). Additionally, many of these banks are important for 

commercial or recreational fisheries because they provide habitat for recruitment and concentrate 

harvestable quantities of fish (Rezak et al., 1983). There is also a diverse group of tropical reef fish 

species found on these banks. There are over 175 tropical reef species that reside within the highdiversity zone at the Flower Garden Banks (Dennis and Bright, 1988; Pattengill, 1998).

Midshelf Banks

The midshelf banks typically have less vertical relief than the shelf-edge banks and are 

present in waters that have less light penetration due to primary production or sediment loading. As 

such, the presence of reefs built by hermatypic corals is rare and limited to Stetson Bank (part of the 

Flower Garden Bank National Marine Sanctuary). Most benthic species on these banks are 

ahermatypic (i.e., non-reef building) corals, algaes, and sponges. The nepheloid layer often enfolds 

many of these banks because most have a lower profile than the shelf edge banks. This can 

influence light penetration and ultimately reduce biodiversity to the most robust species. Midshelf 

banks are known to concentrate many pelagic species of fishes and are visited regularly by 

commercial and recreational fishermen (Simmons et al., 2014).

South Texas Banks

The South Texas Banks are geographically and geologically distinct from the shelf-edge and 

midshelf banks (Rezak and Bright, 1981b; Berryhill et al., 1987). Several of the South Texas Banks 

are also low-relief banks comprised of a series of patch-reef habitats. Many of these banks were 
4-146 Gulf of Mexico Multisale EIS

created from the exposure of fossilized shorelines along the prehistoric coastline or from drowned 

reefs created during a period when sea levels were considerably lower. These banks exhibit a 

reduced biota and have relatively low relief compared with the other banks, few hard-substrate 

outcrops, and a thicker sediment resulting from the presence of a nepheloid layer covering many of 

the banks (Rezak et al., 1983). The dominant benthic species on the South Texas Banks include 

sponges, hydroids, octocorals, and ahermatypic corals, although large areas of these reefs remain 

barren (Rezak and Bright, 1983; Dokken et al., 1993). These banks are known to provide habitat for 

many species of commercially and recreationally important species of fishes. These habitats are 

also important because they are closer to shore than many of the other banks and comprise the 

backbone of the recreational fisheries in that area (Simmons et al., 2014).

Environmental Sensitivity of Banks

The importance of these topographic features to GOM ecology and stakeholders has long 

been understood by BOEM. It is also known that the same geologic processes that create these 

topographic features also create reservoirs where hydrocarbons can become trapped and 

subsequently harvested. As such, in the 1970’s, BOEM’s predecessor developed the Topographic 

Features Stipulation to ensure that the most sensitive sections of these features were not negatively 

impacted by OCS oil- and gas-related activities. The primary concern was sediment deposition and 

subsequent smothering of organisms during drilling operations. As such, BOEM funded a series of 

exploratory cruises to better understand the ecology of these banks. The result was an 

environmental priority index to rate the sensitivity of topographic features (Rezak and Bright 1981a). 

From this index, BOEM developed the No Activity Zones and additional discharge restrictions. The 

Topographic Features Stipulation imposes these No Activity Zones and requirements have 

historically been applied in the GOM since 1973. In order of decreasing sensitivity, the following 

classification was used: 

(1) Shelf-edge, carbonate banks bearing clear-water coral reefs and Algal-Sponge 

Zones, transitional assemblages approximating the Antipatharian Zone and 

Nepheloid Zone (surrounding depths of 276-656 ft [84-200 m], crests 49-246 ft

[15-75 m]).

(2) Midshelf, Tertiary-outcrop banks bearing clear-water, Millepora-Sponge Zone 

and turbid-water-tolerant Nepheloid Zone (surrounding depths of 164-203 ft 

[50-62 m], crests 59-131 ft [18-40 m]).

(3) Midshelf and South Texas carbonate banks bearing poorly developed elements 

of the Algal-Sponge Zone, transitional Antipatharian Zone assemblages, and 

Nepheloid Zone (surrounding depths of 328-361 ft [100-110 m], crests 

220-240 ft [67-73 m]).

(4) Midshelf and South Texas banks bearing turbidity-tolerant assemblages 

approximating the Antipatharian Zone and Nepheloid Zone (surrounding depths 

of 197-262 ft [60-80 m], crests 184-230 ft [56-70 m]).
Description of the Affected Environment and Impact Analysis 4-147

The most sensitive features to turbidity were given the greatest protection. For example, the 

Flower Garden Banks were given the most liberal No Activity Zone and a 4-mi (6-km) buffer where 

discharge restrictions are in place. Banks like McGrail Bank were given No Activity Zones that 

outlined the most sensitive habitats and a 1-mi (1.6-km) zone and a 3-mi (4.8-km) zone with varying 

degrees of discharge regulations. Banks like Sackett Bank have only a No Activity Zone and a 

3,280-ft (1,000-m) zone where discharge restrictions are in place. Finally, low-relief banks with a 

high degree of tolerance for turbidity like Big Adam Bank only have a No Activity Zone.

There is evidence of a large-scale die-off of seaweeds and rhodoliths on several topographic 

features (Sackett and Ewing Banks) that occurred in 2010, possibly related to changes in 

environmental conditions and, as of 2013, there was only a limited recovery (Felder et al., 2014; 

Fredericq et al., 2014). The result is a reduction in diversity and abundance of benthic species at 

Ewing Bank, a reduction in abundance of benthic species at Sackett Bank, and an increase in 

injuries and population declines of decapods at both banks. Although there was little in situ

recovery, it was found that the rhodoliths on these banks may be functioning as a “seed bank” for 

these habitats (Felder et al., 2014; Fredericq et al., 2014). This suggests that there is an unknown 

environmental variable in-place that may be preventing in situ conditions required for recovery.

The ultimate cause of these changes remains unknown; however, this area was subjected to 

ecosystem level insults from 2009 through 2012, in addition to the Deepwater Horizon explosion and 

oil spill. With respect to oil exposure, Sackett and Ewing Banks had some degree of exposure in the 

surface waters. There is no direct evidence that implicates oil-related impacts as the trigger for 

these changes (Felder et al., 2014; Fredericq et al., 2014). However, to place these banks in a 

wider environmental context, they 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 with normal outfall patterns (Pollak, 2013). From late 2009 to late 2010 and 2011, the 

Mississippi River maintained an exceptionally high flow rate with an abnormal seasonal pattern, and 

this was followed by record low outfall levels in 2012. These areas were also subjected to differing 

levels of hypoxia, with major hypoxic events occurring in the vicinity of Ewing Bank in the summers 

of 2009, 2010, and 2011 (USDOC, NOAA, 2010d and 2015j). Although there were many hypoxic 

events prior to 2009, these occurred during periods of river outfall patterns exhibiting a more 

“normal” seasonal pattern, possibly impacting these banks. Finally, the banks of the northern GOM 

also experienced exponential population growth of the invasive lionfish (Pterois volitans) during this 

same time period (USDOI, GS, 2015; Johnston et al., 2013). This fish is known to drive down 

diversity and abundance of benthic organisms, especially crabs, demersal fishes, and shrimps 

(Green et al., 2012). The lionfish expansion could result in a top-down control of grazers, ultimately 

preventing recolonization by seaweeds due to increased grazing on seaweed recruits by herbivores 

released from decapod predation due to lionfish. It is a reasonable conclusion that the possible 

ecosystem-level changes on these two banks are the result of the cumulative impacts of many 

factors (e.g., Karnauskas et al., 2015) rather than a single cause-effect relationship (i.e., the 

Deepwater Horizon oil spill), especially with respect to recovery.
4-148 Gulf of Mexico Multisale EIS

Habitat Areas of Particular Concern and Endangered Species Act Listings

The NMFS has designated habitat areas of particular concern (HAPCs) within identified 

EFHs. The HAPCs provide important habitat for federally managed fish species and are areas for 

conservation priorities. Designation is based on habitat ecological importance, sensitivity to fishing, 

sensitivity to nonfishing, developmental stress, and rarity (GMFMC, 2005 and 2010). The only bank 

designated as coral HAPC is McGrail Bank (GMFMC, 2005 and 2010; Simmons et al., 2014). Hardbottom HAPCs include Sonnier Bank, Geyer Bank, Bouma Bank, Rezak Bank, Sidner Bank, 

Alderice Bank, Jakkula Bank, and parts of McGrail Bank (GMFMC, 2005 and 2010; Simmons et al., 

2014). The HAPC designation has no regulatory consequences for BOEM-permitted activities; 

however, BOEM does consult with the NMFS on issues related to HAPCs when appropriate. Finally, 

in 2014, 20 additional corals were listed as threatened under the ESA, and several of these species 

are found in the northern GOM (Federal Register, 2014b). For more information on these corals, 

refer to Chapter 4.9.6. 

4.6.1.2 Environmental Consequences

Routine Events

The only potential routine impact-producing factors that could affect topographic features in 

the GOM are caused by bottom-disturbing activities that may occur during drilling and exploration 

operations and vessel operations.

Drilling, Exploration, and Decommissioning Operations

Bottom-disturbing activities can be described as any activity that results in the disturbance of 

the seabed during the exploration, production, or decommissioning phase of OCS operations. This 

includes (but is not limited to) drilling activities (Chapters 3.1.2 and 3.1.3.1), structure installation 

and removal (Chapters 3.1.3.3 and 3.1.6), and pipelaying activities. Regardless of the activity, the 

severity of the impact to topographic features is the same, although the extent of the impact may 

vary. For example, the placement of a bottom-founded platform would result in a larger impact area 

compared with a pipeline passing across a feature; however, both would result in the loss of 

organisms.

The bottom-disturbing activity with the largest areal impact would be the discharge of 

cuttings into the water column. Operations in close vicinity to topographic features could deposit 

large amounts of sediment onto the features (maximum amounts estimated to be approximately 

2,000 metric tons) (Neff, 2005). This could have severe impacts, including increased stress as the 

organisms cope with the increased sediment load, a decline in production due to decreased light, or 

mortality caused by smothering (Wilber et al., 2005). Sedimentation of uncolonized substrates could 

also render these areas uninhabitable for future recruits settling on the topographic feature; 

however, with the proposed mitigation defining the No Activity Zones, potential impacts are reduced 

to negligible. Additionally, once the casings are emplaced and cuttings are no longer being 

discharged, the impact of routine bottom-disturbing activities becomes negligible. 
Description of the Affected Environment and Impact Analysis 4-149

The placement of any structures or equipment on the seafloor would also result in substantial 

impacts to the benthic communities on the topographic features. Any object placed on the seafloor 

could result in the crushing deaths of any organisms contacted during emplacement activities. 

Mortality due to smothering could also occur if sediments are moved from the seafloor to a new 

location (e.g., trenching a pipeline or emplacement of initial casings). Sedimentation of uncolonized 

substrates could also render these areas uninhabitable for future recruits to settle on the topographic 

feature.

Explosive severance for the removal of structures is another bottom-disturbing activity 

associated with OCS oil- and gas-related operations that can impact the community of the 

topographic features. This would result in damage or death to any organisms within the vicinity of 

the blast or associated sediment plume, although long-term turbidity is not expected from platform 

removal operations. The shockwave from the blast could also damage or destroy the underlying 

hard substrates required by many benthic organisms.

Without adherence to the distancing and shunting requirements of the Topographic Features 

Stipulation, impacts to topographic features would be severe and long lasting. However, if the 

requirements of the Topographic Features Stipulation are applied, operations would remain a safe 

distance away from critical areas of topographic features and no impacts would be expected. 

Additionally, restrictions on discharges would be in place and few organisms would experience 

substantial levels of sedimentation. It is expected that this stipulation would continue to be a 

requirement for OCS operators throughout the entire time period covered by this analysis (2017-

2022). With adherence to the requirements of the Topographic Features Stipulation, impacts would 

be negligible. 

Vessel Operations

The only aspect of routine vessel operations that would result in bottom-disturbing activities 

that could impact topographic features would be the use of anchors by vessels. Anchor damage is 

one of the greatest threats to the biota of the offshore banks in the GOM (Rezak and Bright, 1979; 

Rezak et al., 1985; Gittings et al., 1992a; Hudson et al., 1982). Anchors may break, fragment, or 

overturn corals, sponges, and other benthic organisms, and the anchor chain or cable may drag 

across and shear organisms off the substrate (Dinsdale and Harriott, 2004). This would result in 

consequences ranging from increased stress to mortality (Dinsdale and Harriott, 2004). Damage to 

a coral community may take 10 or more years to recover (Fucik et al., 1984; Rogers and Garrison, 

2001).

Without adherence to the distancing requirements of the Topographic Features Stipulation, 

any impacts to topographic features would be severe and long lasting. However, if the requirements 

of the Topographic Features Stipulation are applied, anchor placement from OCS oil- and gasrelated vessels would not be allowed on or near the most sensitive areas of the features and impacts 

would be negligible. 
4-150 Gulf of Mexico Multisale EIS

Accidental Events

The potential impact-producing factors resulting from accidental events on topographic 

features in the GOM include bottom-disturbing activities, release of toxins and sediment into the 

water column, and an oil spill and associated cleanup activities. Each of these impact-producing 

factors can occur during hydrocarbon extraction activities or during vessel operations.

Drilling, Exploration, and Decommissioning Operations

Bottom-Disturbing Activities

The only reasonably foreseeable accidental bottom-disturbing activity is the deposition or 

placement of equipment on a topographic feature. Accidental loss of equipment could occur during 

transfer operations between vessels and platforms, while in transit on vessels, from “on deck” 

accidents on platforms, or as a consequence of a storm event. They could also occur if a platform 

(or other structure) is placed in the wrong location during installation. Regardless of the cause, the 

consequence would be the same. Any organisms that are underneath the equipment would suffer a 

mortality event. The degree of impact would be directly related to the size of the equipment. Large 

pieces of equipment could also influence water-flow patterns on or around topographic features, 

potentially influencing the movement of larvae and food. However, any equipment that is deposited 

on the seafloor would become a new substrate that could be colonized by benthic organisms, 

potentially providing larvae to new areas and enhancing the biodiversity of an area while the 

structure remains in place. Any recovery operations would have to abide by the stipulation’s 

restrictions, and bottom-disturbing activities would be prohibited.

Without adherence to the distancing requirements of the Topographic Features Stipulation, 

impacts to topographic features would be severe and long lasting. However, if the requirements of 

the Topographic Features Stipulation are applied, impacts would be restricted to losses of 

equipment from vessels that happen to be over a topographic feature when the loss occurs, from 

equipment that drifts before sinking, or from storm-related movement. Most equipment would be 

expected to be in use outside of the No Activity Zone, except for transit. Although damage from 

equipment hitting a topographic feature would have a deleterious effect at the impact site, the low 

probability of an accidental event, combined with the reduced probability of equipment falling from a 

vessel with the correct trajectory to contact a topographic feature, and the relatively small area that 

these features occupy, the possibility of this type of impact occurring is minuscule. Because of the 

unlikelihood of such events, the understanding that impacts would be limited in size and scope, and 

assumed in compliance with the stipulation, the overall impact of accidental bottom-disturbing 

activities is expected to be negligible. 

Chemical and Drilling-Fluid Spills

Any release of toxins into the water column would result from a spill from a platform or 

vessel. Spills could include releases of substances such as diesel fuel, marine paint, drilling fluids, 

and untreated sewage, or could occur through the incorrect separation of cuttings and drilling muds 

(Chapter 3.2.6). Most spills on the OCS would have little impact on the organisms of a topographic 
Description of the Affected Environment and Impact Analysis 4-151

feature because spills of this type are expected to be relatively small, and the substance would 

either remain in the surface waters or would be rapidly diluted and dispersed. For substances like 

drilling muds, an accidental release could have substantial impacts to a topographic feature as those 

materials rapidly settle to the seafloor, smothering any organisms that cannot cope with large 

quantities of sediments. However, the impact would be proportional to the size of the spill. The 

composition of muds is strictly regulated, and discharges of cuttings/muds are tested to ensure that 

toxicity levels are below the limits allowed by NPDES permits (USEPA, 2004, 2007, and 2009b). It 

is expected that any spill would be stopped quickly or would be relatively small given the limitations 

on how transfer occurs between vessels and platforms. Quantities are limited by the lifting ability of 

the cranes or reliance on hoses to transfer fluids from vessels to platforms. Exposures to drilling 

mud concentrations can result in a wide range of impacts to corals, ranging from mortality to multiple 

sublethal responses to no response at all (Thompson, 1979).

Without adherence to the distancing requirements of the Topographic Features Stipulation, 

any impacts to topographic features would be moderate and long lasting. However, if the 

requirements of the Topographic Features Stipulation are applied, any impacts would be restricted 

because of the increased distance the feature would be from an OCS oil- and gas-related operation. 

This would allow more time and distance for dilution and dispersion of substances or allow more 

distance for substances to settle on the seafloor. Given that the probability of an accident is 

inherently low and adherence to the Topographic Features Stipulation, combined with the reduced 

probability of this type of spill occurring at a structure near a topographic feature, the impact of 

accidental releases of toxins into the water column is negligible. 

Vessel Operations

The aspect of vessel operations that would result in bottom-disturbing activities that could 

impact topographic features would be the use of anchors during an accident or an emergency (e.g., 

loss of propulsions). Anchoring impacts during an accidental event would be similar to those 

outlined above in the “Routine Activities” section for vessel operations.

Regardless of the Topographic Features Stipulation, anchor placement during an emergency 

would occur to preserve the safety of the vessel and crew. Impacts to benthic organisms on 

topographic features would be severe at the location where the anchor lands; however, they would 

be limited to that location and not likely to threaten communities across the entire topographic 

feature. In addition, an accident requiring anchoring would be an isolated event, and responding 

vessels would not be expected to anchor. Overall, the impacts of an anchoring event that occurs 

during an emergency would have a negligible impact on an entire topographic feature, even if it did 

have severe impacts at the anchoring location.

Oil Spill and Cleanup Activities

Impacts that may occur to benthic communities on topographic features as a result of a spill 

would depend on the type of spill, distance from the spill, relief of the biological feature, and 

surrounding physical characteristics of the environment (e.g., turbidity). Oil transport and fate is 
4-152 Gulf of Mexico Multisale EIS

discussed in Chapter 3.2.1.3, and oil spills <1,000 bbl and oil spills ≥1,000 bbl are discussed in 

Chapters 3.2.1.4 and 3.2.1.5, respectively. In large enough quantities, this could result in lethal or 

sublethal impacts to organisms, reducing fitness, growth, or reproduction. Therefore, the depth of 

topographic features below the sea surface should minimize contact with surface oil where it is 

advected away or cleaned up by response crews.

If an oil spill occurs at depth in deep water and the oil is ejected under pressure, some oil 

would rise to the surface, but some oil droplets may become entrained deep in the water column 

(Boehm and Fiest, 1982), creating a subsurface plume (Adcroft et al., 2010). If this plume was to 

come in contact with the benthic organisms on a topographic feature, the impacts could range from 

negligible to severe, including mortality; loss of habitat, biodiversity, and live coverage; change in 

community structure; and failed reproductive success (Reimer, 1975; Guzmán and Holst, 1993; 

Negri and Heyward, 2000; Silva et al., 2015). Impacts would depend on the location and weathering 

of the oil and the hydrographic characteristics of the area (Bright and Rezak, 1978; Rezak et al., 

1983; McGrail, 1982; Le Henáff et al., 2012). Because all of the topographic features are located on 

the shelf and because upwelling events are limited to hurricanes, eddy formations, or when certain 

meteorological conditions exist (Walker, 2001; Collard and Lugo-Fernandez, 1999; Zavala-Hidalgo 

et al., 2006), contact of a small subsurface plume with a topographic feature would only occur under 

the most ideal and unlikely conditions (Silva et al., 2015). There is a possibility that, if a subsurface 

plume becomes entrained into the nepheloid layer, organisms in this layer could be greatly 

impacted. In shallow waters, this layer is typically restricted to the bottom 66 ft (20 m) of the water 

column (Bright et al., 1976; Bright and Rezak, 1978).

If dispersants are used on a larger spill (refer to Chapter 3.2.7.2.3), they would enable oil to 

mix into the water column and possibly impact organisms on the topographic features. However, 

dispersant use is not anticipated except on the largest spills. For a surface spill, dispersed oil is not 

expected to reach the topographic feature (Guo et al., 2014; Lange, 1985; Tkalich and Chan, 2002); 

however, for a subsurface plume where dispersants were applied, any dispersed oil in the water 

column that comes in contact with corals may evoke short-term negative responses by the 

organisms, such as reduced feeding and photosynthesis or altered behavior (Wyers et al., 1986; 

Cook and Knap, 1983; Dodge et al., 1984; Ross and Hallock, 2014). For larvae, the response may 

be more profound (Goodbody-Gringley et al., 2013). As such, the use of dispersants during coral 

spawning season should only be used under the most dire circumstances (Negri and Heyward, 

2000; Goodbody-Gringley et al., 2013). However, outside of the spawning season, dispersanttreated areas may recover more rapidly than areas where oil is allowed to decay naturally (Lessard 

and Demarco, 2000).

For any accident, it is also expected that a certain quantity of oil may settle on the seafloor 

due to a binding process with suspended sediment particles or after being consumed and excreted 

by phytoplankton (International Tanker Owners Pollution Federation Limited, 2002; Passow et al., 

2012). It is anticipated that the greatest amount of oil adsorbed to sediment particles would occur 

close to the spill, with reduced concentrations farther from the source. If the spill occurs close to a 

topographic feature, the underlying benthic communities may become smothered by the particles 
Description of the Affected Environment and Impact Analysis 4-153

and exposed to hydrocarbons. Beyond that area, impacts are expected to be negligible to minor

as particles are biodegraded and become more widely dispersed. Sublethal impacts to benthic 

organisms from such exposure may include reduced recruitment success, reduced growth, and 

reduced coral cover as a result of impaired recruitment (Rogers, 1990; Kushmaro et al., 1997).

During a response operation, drilling muds may be pumped into a well to stop a loss of well 

control. It is possible that during this process this mud may be forced out of the well and deposited 

on the seafloor near the well site. If this occurs, the impacts would be severe for the organisms 

buried; however, the impact beyond the immediate area would be limited.

Without adherence to the distancing requirements of the Topographic Features Stipulation, 

impacts to topographic features could be severe and long lasting due to oiling, cleanup activities, 

toxins from dispersants, or bottom-disturbing activities. However, if the requirements of the 

Topographic Features Stipulation are applied, impacts would be negligible to minor, short in 

duration, and limited to the topographic feature where the accident occurs.

Cumulative Impacts

The cumulative impact of OCS oil- and gas-related routine activities and accidental events 

considered include bottom-disturbing activities (e.g., anchoring, structure emplacement and removal, 

muds and cuttings discharges) and accidental events (e.g., bottom disturbance, the discharge of oil, 

or spill cleanup). Any bottom-disturbing activities would be considered to be a catastrophic threat to 

the biota of topographic features. However the proposed Topographic Features Stipulation has 

been in effect for decades and is expected to remain in effect; it is therefore assumed to be in effect 

for this analysis. Adherence to these restrictions would prevent adverse impacts on benthic 

communities of topographic features (refer to Chapter 2.2.4.1).

Potential non-OCS oil- and gas-related cumulative impact factors include anchoring, fishing, 

recreational diving, the presence of invasive species, and natural events (e.g., hurricanes). 

However, because of the spatial extent of the topographic features and the management activities of 

other agencies, the only reasonably foreseeable effect on topographic features could be the effect of 

anchoring on the features.

OCS Oil- and Gas-Related Impacts

Bottom-disturbing activities could result in the physical destruction of benthic habitat and 

organisms or the disturbance of the sediments within the environment, resulting in burial or 

increased stress. Given adherence to the siting restrictions of the Topographic Features Stipulation, 

the cumulative impacts of OCS Oil and Gas Program operations have been negligible to date. An 

example of this is the continued high degree of coral coverage and biodiversity documented by the 

long-term monitoring program at the Flower Garden Banks National Marine Sanctuary (Johnston 

et al., 2015). The area in the vicinity of the Sanctuary has seen a substantial amount of oil and gas 

production for decades, and coverage by benthic organisms has remained stable.
4-154 Gulf of Mexico Multisale EIS

Impacts on the topographic features could occur as a result of OCS oil spills. To date, 

previous noncatastrophic spills have not had any identifiable impact (cumulative or otherwise) on 

any topographic features. Because of the Topographic Features Stipulation, siting restrictions 

facilitate spills reaching the surface before contacting the features. For oil on the surface, the depths 

of the crests of the topographic features are deep enough (>49 ft; >15 m) that surface oil should not 

reach topographic features in sufficient concentrations to cause impacts. Deep mixing of oil is 

possible during extreme weather events and could result in negative impacts on deep habitats (Silva 

et al., 2015). Excluding these events, dispersed surface oil that may reach the benthic communities 

of topographic features in the GOM would be expected to be at a low enough concentration to not 

have any discernable long-term impacts (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Dodge 

et al., 1984; Wyers et al., 1986). In total, it is expected that, given adherence to the proposed 

stipulations, the cumulative impact would remain negligible. 

Non-OCS Oil- and Gas-Related Impacts

The potential impacts to topographic features from non-OCS oil- and gas-related sources 

include anchoring, fishing, hurricanes, damage by recreational scuba diving, and the presence of 

invasive species. Most of these features are deep enough that scuba diving activities are limited. In 

most areas where diving is possible, that activity is managed by other Federal agencies that protect 

habitats from modification or destruction.

Hurricanes are considered a rare event at any given location (refer to Chapter 3.3.2.9.3); 

however, they are a natural event within the environment, and these habitats have adapted to deal 

with these storms over millennia. As such, hurricanes may alter the environment and kill organisms; 

however, they are not considered “impacts” because they remain a normal part of the life cycle of a 

topographic feature.

Because many of the topographic features are found near established shipping fairways and 

are well-known fishing areas, vessel anchoring at a topographic feature could and has damaged the 

biota (refer to Chapter 3.1.3.3.1). The degree of damage is dependent on the size of the anchor 

and chain (Lissner et al., 1991). Anchor damages incurred by benthic organisms may take more 

than 10 years to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and 

Garrison, 2001). The combined impact of anchoring activities on topographic features is unknown, 

but anchoring is only prohibited at four of the recognized topographic features. Three of these 

features are included in the Flower Garden Banks National Marine Sanctuary and the other (McGrail 

Bank) is designated a coral HAPC. Within the Flower Garden Banks National Marine Sanctuary, all 

anchoring is prohibited; in the coral HAPC, anchoring is only restricted to fishing vessels.

Fishing pressure could alter fish community structure and potentially have a top-down trophic 

impact on fish populations, ultimately impacting the benthic community. This could occur though 

unsustainable harvest practices; however, most managed fish populations in the GOM are stable or 

recovering. Harvest activities are managed and monitored by other government agencies, and 

populations are not expected to be depleted to a point where benthic populations are impacted. The 
Description of the Affected Environment and Impact Analysis 4-155

recent invasion by lionfish may alter fish and invertebrate populations on topographic features 

(Johnston et al., 2015). The predatory nature of this fish, combined with the lack of natural 

predators, suggests that a population explosion of lionfish could result in a top-down impact of 

benthic organisms. The result would be a decrease in biodiversity and abundance of many of the 

smaller organisms that use the benthic habitats found on topographic features. Given the spread of 

reported lionfish sightings across the GOM, it is possible that they are present on all of the 

topographic features. The impacts are still unknown as populations are still increasing exponentially 

(Switzer et al., 2015).

Given that all OCS oil- and gas-related anchoring activities have been and remain prohibited 

or regulated on and around topographic features, and that citing restrictions minimize the potential 

for an accidental oil spill to contact topographic features, the probability of an OCS oil- and gasrelated activity increasing the impact of any non-OCS oil- and gas-related activities is low. In 

addition, the same restrictions on proposed activities reduce the probability of any OCS oil- and gasrelated activity associated with a proposed action, increasing the effects of previous OCS oil- and 

gas-related activities. In contrast, non-OCS oil- and gas-related impacts could potentially damage 

and disrupt topographic features because many of the effects are highly variable and unpredictable. 

Overall, impacts of non-OCS oil- and gas-related activities are expected to range between 

negligible to moderate depending on the amount of activity in the vicinity of the features, impacts of 

fishing regulations, and the continued presence of pollution in the GOM. As such, the incremental 

contribution of a proposed lease sale is negligible, as the overall cumulative impacts of a proposed 

lease sale, combined with non-OCS oil- and gas-related activities, is expected to be negligible. 

Incomplete or Unavailable Information

After evaluating the information above, BOEM has determined that a substantial amount of 

information remains unknown about these features; however, the information that is known is 

adequate to come to a reasonable determination with respect to the impact-producing factors 

associated with a proposed action. Research in deep marine systems is complex and requires 

substantial resources; as such, research on these features has been limited. 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 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 1981a; Tkalich and Chan, 2002; Rezak et al., 1983; Wyers et al., 1986). Mixing to depth 

might occur, but it would be limited to when tropical storms pass in close proximity to the spill (Silva 

et al., 2015). 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., 2015, and references therein). At 

the Flower Garden Banks, corals have flourished while OCS oil- and gas-related development has 

occurred and, in some cases, activities have taken place just outside the No Activity Zone. Since 
4-156 Gulf of Mexico Multisale EIS

corals are generally considered to be more fragile than most other organisms found on topographic 

features, it is reasonable to conclude that topographic features with more resilient organisms than 

the Flower Garden Banks have not been negatively affected 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, much 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 GOM. 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. 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 the 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.

4.6.1.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Adherence to the proposed Topographic Features Stipulation would prevent most of the 

potential impacts on topographic feature communities from loss of well control, surface and 

subsurface oil spills, and routine activities by increasing the distance of such events from the 

topographic features. During an accidental event, it would be expected that the majority of oil would 

rise to the surface and that the most heavily oiled sediments would likely be deposited before 

reaching the topographic features. Any contact with spilled oil would likely cause sublethal effects to 

benthic organisms because the distance of activity would prevent contact with concentrated oil. In 

the unlikely event that oil from a subsurface spill would reach the biota of a topographic feature, the 

effects would be primarily sublethal and impacts would be at the community level. Most turbidity, 

sedimentation, and oil adsorbed to sediment particles would also be at low concentrations by the 

time the topographic features were reached, also likely resulting in primarily sublethal impacts. 

Impacts from an oil spill on topographic features are also lessened by the depth of the features and 

the currents that surround the features. This alternative would also do little to reduce the cumulative 

impacts to topographic features as many blocks near the features are already leased and non-OCS 

oil- and gas-related activities are not expected to decrease. Overall, any impacts to topographic 

features from routine activities and accidental events or the cumulative impact of a proposed action 

in the GOM is expected to be negligible or moderate and isolated. The size and scope of the 

impacts would be directly proportional to the size of an accident and the efforts to remedy the 

effects. However, because topographic features are spread across the GOM, localized impacts at 

one topographic feature does not preclude that impacts would occur at other topographic features.
Description of the Affected Environment and Impact Analysis 4-157

4.6.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, the impacts of routine activities to topographic features would remain 

the same in the CPA as under the Alternative A, while most features in the WPA would not be 

directly impacted. Overall, there are 16 topographic features in the CPA and 0 in the EPA. Any 

impacts resulting from accidental events in the CPA and/or EPA would remain localized, and the 

number of features affected would be directly proportional to the size of the accident. An accident 

along the CPA/WPA border has the possibility to impact features in either planning area. This 

alternative would do little to reduce the cumulative impacts to topographic features as many blocks 

near the features are already leased and non-OCS oil- and gas-related activities are not expected to 

decrease. Overall, any impacts to topographic features from routine activities and accidental events 

or the cumulative impact of a proposed lease sale in the GOM is dependent on the extent of the 

activity but is expected to be negligible or moderate without adherence to the Topographic 

Features Stipulation, but the impacts should remain negligible with adherence to the stipulation. 

While the CPA/EPA has the greatest potential for OCS oil- and gas-related activity, topographic 

features are dispersed across the shelf area. As such, any localized impacts would not result in 

impacts across the entire shelf area, resulting in no population-level impacts.

4.6.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Under Alternative C, the impacts of routine activities to topographic features would remain 

the same in the WPA while features in the CPA would not be directly impacted. Any impacts 

resulting from accidental events in the WPA would remain localized, and the number of features 

affected would be directly proportional to the size of the accident. An accident along the CPA/WPA 

border has the possibility to impact features in either planning area. This alternative would do little to 

reduce the cumulative impacts to topographic features as many blocks near the features are already 

leased and non-OCS oil- and gas-related activities are not expected to decrease. Overall, any 

impacts to topographic features from routine activities and accidental events or the cumulative 

impact of a proposed action in the GOM would be directly related to the extent of the activity, but is 

expected to be negligible or moderate without adherence to the Topographic Features Stipulation, 

but the impacts should remain negligible with adherence to the stipulation. While the WPA has less 

potential for OCS oil- and gas-related activity than the CPA, topographic features are dispersed 

across the shelf area. As such, any localized impacts would not result in impacts across the entire 

shelf area, resulting in no population-level impacts.

4.6.1.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, topographic features could be further protected by distancing OCS oiland gas-related activities farther from these habitats, reducing the probability of impacts. An 

accidental spill may still reach a feature, but it is expected that the increased distance would provide 
4-158 Gulf of Mexico Multisale EIS

more dispersal time as the spill travels the additional distance across unleased blocks. This 

alternative would do little to reduce the cumulative impacts to topographic features as many blocks 

near the features are already leased and non-OCS oil- and gas-related activities are not expected to 

decrease. Overall, any impacts to topographic features from routine activities and accidental events 

or the cumulative impact of a proposed action in the GOM is expected to be negligible. Blocks 

subject to the Topographic Features Stipulation include any available unleased block in which a No 

Activity Zone or Shunting Zone may be applied. A total of 207 blocks within the CPA and 160 blocks 

in the WPA are affected by the Topographic Features Stipulation. For additional information related 

to the specific blocks that would be excluded, refer to Chapter 2. The exclusion of any of the other 

blocks subject to either the Live Bottom (Pinnacle Trend) and/or Blocks South of Baldwin County, 

Alabama, Stipulations is not expected to change the impacts to topographic features because of the 

small number of blocks and their distance from identified topographic features.

4.6.1.2.5 Alternative E—No Action

Under Alternative E, there would be no impacts to topographic features; however, the 

impacts would be limited to cumulative impacts associated with previous OCS oil- and gas-related 

development and non-OCS oil- and gas-related activities.

4.6.2 Pinnacles and Low-Relief Features

Impact Analysis Process and Scope

This analysis considers the impacts of routine activities, accidental events, and a proposed 

action’s incremental contribution to cumulative impacts on GOM live bottom habitats a 50-year 

period. This analysis is not exhaustive of all possible impacts of routine activities and accidental 

events; rather, it focuses on those related to a proposed action. Because a catastrophic oil spill is 

not reasonably foreseeable, those potential impacts (including long-term recovery) are addressed in 

the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2016c). The impact significance 

criteria and resulting conclusions presented here (Table 4-9) focus on the overall functioning, 

resilience, and ecosystem level importance of live bottom pinnacles and other live bottom low-relief 

features throughout U.S. waters of the GOM. Postlease, site-specific analyses would focus more on 

the potential localized impacts of individual development activities (e.g., proposed drilling of a 

specific well) to individuals, discrete communities, and small patches of live bottom habitat. Those 

analyses would also detail site-specific protective mitigations required prior to approval of such 

activities.
Description of the Affected Environment and Impact Analysis 4-159

Table 4-9. Pinnacles and Low-Relief Features Impact-Producing Factors.

Pinnacles and

Low-Relief Features Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Bottom-Disturbing Activities and Drilling-related Sediment and Waste Discharges

Without Mitigation

Minor to Minor to Negligible to Negligible to None

Major Moderate Minor Minor

With Mitigation Negligible Negligible Negligible Negligible None

Accidental Impacts

Bottom-Disturbing Activities and Drilling-Related Sediment and Operational Waste Discharges

Without Mitigation

Minor to Minor to Negligible to Negligible to None

Major Moderate Moderate Moderate

With Mitigation Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Oil Spills

Without Mitigation

Minor to Minor to Negligible to Negligible to None

Major Moderate Moderate Moderate

With Mitigation Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Cumulative Impacts

OCS Oil and Gas

With Mitigation Negligible Negligible Negligible Negligible Negligible

Non-OCS Oil and Gas

All Combined 

Non-OCS ImpactProducing Factors

Minor to Minor to Minor to Minor to Minor to

Major Major Major Major Major

Impact-Level Definitions

For this analysis, the definitions below were used to categorize impacts to pinnacles and 

low-relief features.

• Negligible – Impacts to live bottom communities are largely undetectable. There 

is some potential for even undetectable impacts to cause slight changes to a 

local community’s species abundance and composition, community structure, 

and/or ecological functioning, but any such changes would be spatially localized, 

short term in duration, and would not alter the overall status of GOM live bottom 

communities.

• Minor – Impacts to live bottom communities are detectable but cannot be clearly 

distinguished from natural variation. Such impacts could result in noticeable 

changes to a local community’s species abundance and composition, community 
4-160 Gulf of Mexico Multisale EIS

structure, and/or ecological functioning, but any such changes would be spatially 

localized, short term in duration, and would not alter the overall status of GOM 

live bottom communities.

• Moderate – Impacts to live bottom communities detectably cause substantial, 

population-level changes in species composition, community structure, and/or 

ecological functioning. These impacts would be expected to be spatially 

extensive, but they are expected to only temporarily alter the overall status of 

GOM live bottom communities such that long-term recovery to pre-impact levels 

is likely.

• Major – Impacts to live bottom communities detectably cause substantial, 

population-level changes in species composition, community structure, and/or 

ecological functioning. These impacts would be expected to be spatially 

extensive and to noticeably alter the overall status of GOM live bottom 

communities such that long-term recovery to pre-impact levels is unlikely.

The primary relevant, reasonably foreseeable impacts of routine activities and accidental 

events to live bottom habitats described in this chapter can be grouped into the following three 

general categories:

(1) bottom-disturbing activities (routine and accidental);

(2) drilling-related sediment and waste discharges (routine and accidental); and

(3) oil spills (accidental).

These impacts are analyzed in detail under the “Routine Activities” and “Accidental Events” 

sections below. Cumulative Impacts were also considered in two steps: cumulative impacts 

resulting from OCS oil- and gas-related activities and impacts resulting from non-OCS oil- and gasrelated activities.

Some impact-producing factors relevant to live bottom communities are analyzed in detail in 

other chapters and need only be briefly summarized here. Chapter 4.7 (Fishes and Invertebrate 

Resources) details impacts from anthropogenic noise. Note that despite the growing body of 

information available for fishes, there is comparatively little information available on sound detection 

and sound-mediated behaviors for marine invertebrates. That said, the overall impacts on live 

bottom communities from anthropogenic noise are expected to be negligible. Chapter 4.7 also 

details the impacts of routine activities and the cumulative impacts from OCS oil- and gas-related 

infrastructure presence, subsequent removal, and/or conversion to artificial reefs. While the total 

contribution of OCS infrastructure is still only a small percentage of natural hard bottoms (Gallaway 

et al., 2009) and is projected to further decrease throughout the period covered by this analysis 

(Chapter 3.3.1.5), the presence, removal, and/or conversion of artificial hard substrates colonized by 

sessile invertebrates are likely to result in localized community changes, such as changes in species 

diversity in an area (Schroeder and Love, 2004). While individual presence, removal, or conversion 
Description of the Affected Environment and Impact Analysis 4-161

actions at specific locations do not cause more than negligible impacts when considered against the 

broader scope of this analysis, when the sum of such actions are considered cumulatively for all 

planning areas and over 50 years, such impacts could be greater for individual species. This is 

because select species commonly associated with OCS oil and gas platforms could be noticeably 

influenced over time by the overall presence (or removal) of OCS infrastructure. For example, a 

particular hermatypic coral species’ Gulfwide spatial distribution may shift over time because of the 

presence or removal of structures in otherwise soft bottom-dominated areas. Such a change (were 

it to occur) could be considered a moderate level impact (for that species) if it represented a 

detectable change in the species’ spatial distribution; such a range shift might have potential longterm effects related to dispersal and genetic connectivity to other populations of that species. Such 

potential impacts are not necessarily either positive or negative; that would be dependent on the 

species and a number of complex ecological factors. Some evidence of these types of changes (in 

particular, range expansion) has been documented for some shallow-water hermatypic species 

(Sammarco et al., 2012). More peer-reviewed literature about this topic is available for fish 

resources, as detailed in Chapter 4.7 (Fishes and Invertebrate Resources).

Several additional impact-producing factors described in Chapters 3.1 and 3.2 were 

evaluated for potential impacts on live bottom communities. These impact-producing factors were 

not carried forward for full analysis because any potential effects were judged to be either not 

reasonably foreseeable or having such a miniscule impact that they would not rise to the level of 

negligible impact. These impact-producing factors include surface oil-spill response efforts (refer to 

Chapter 4.6.1, Topographic Features), impacts from G&G activities other than bottom disturbance 

(bottom disturbance is covered below), and potential impacts from a sinking vessel. A sinking vessel 

settling on a live bottom community is not a reasonably foreseeable impact-producing factor. Even if 

such an incident did occur, it would not have a population-level impact despite likely crushing or 

smothering live bottom organisms in the area of direct contact.

Some potential impact-producing factors are already regulated by other Federal agencies 

and/or international treaties. For example, the discharge of marine debris is subject to a number of 

laws and treaties. These include the Marine Debris Research, Prevention, and Reduction Act; the 

Marine Plastic Pollution Research and Control Act; and the MARPOL-Annex V Treaty. Regulation 

and enforcement of these laws is conducted by a number of agencies such as the U.S. 

Environmental Protection Agency, NOAA, and the U.S. Coast Guard. To further reduce potential 

impacts, the BSEE provides information on marine debris and requires training of all OCS personnel 

through the “Marine Trash and Debris Awareness and Elimination” NTL (NTL 2015-BSEE-G03). 

Historically, this NTL has been made a binding part of leases through application of the Protected 

Species Stipulation. This NTL instructs OCS operators to post informational placards that outline the 

legal consequences and potential ecological harm of discharging marine debris. This NTL also 

states that OCS workers should complete annual marine debris prevention training; operators are 

also instructed to develop a certification process for the completion of this training by their workers. 

These various laws, regulations, and NTL would likely minimize any potential damage to live bottom 

resources from the discharge of marine debris related to OCS oil- and gas-related operations. 

Nonetheless, some accidental release of marine debris is still likely to occur as a result of OCS oil- 
4-162 Gulf of Mexico Multisale EIS

and gas-related operations and could theoretically have limited effects on live bottom organisms 

(e.g., physical damage caused by strong currents pushing debris into fragile organisms or ingestion 

of plastics by invertebrates). However, the amount of debris in question would not suffice to cause 

even negligible impacts when considered at the scale of the overall population of live bottom 

communities in the GOM. One possible exception would be frequent accidental losses of very large 

items such as pipeline segments with the potential to crush or smother live bottoms. That impactproducing factor is briefly discussed under “Bottom-Disturbing Activities” in the “Accidental Events” 

section below, even though any such losses are expected to be very rare. In all cases, the likelihood 

of spatial overlap with debris from OCS vessels or infrastructure is inherently small due to the 

relatively rare and patchy distribution of live bottom communities in the GOM, particularly in areas of 

the western and northern GOM, which have the greatest amount of OCS oil- and gas-related

operations.

Another potential impact-producing factor that is largely governed by (and potential impacts 

reduced by) external regulations is the potential presence of toxins in drilling muds and cuttings 

and/or produced waters. Because of the regulations issued by the USEPA and/or international 

treaties designed to keep toxins below harmful levels, hazardous levels of toxins are generally not 

expected to reach live bottom communities. Nonetheless, potential impacts from toxins are briefly 

discussed in the “Routine Activities” section below.

Historical Protections of Live Bottom Features

Protective measures have been developed over time based on the nature and sensitivity of 

various live bottom habitats and their associated communities, as understood from decades of 

BOEM-funded and other environmental studies. These protections were developed into stipulations 

historically applied to OCS leases in areas with known concentrations of live bottom features. The 

Pinnacle Trend is a specific series of high- and low-relief hard bottom features occurring just east of 

the Mississippi River. BOEM has consistently applied the Live Bottom Stipulation to 74 OCS lease 

blocks covering this area. The CPA blocks directly adjacent to low-relief blocks are included in a 

proposed action and some of the alternatives; therefore, potential impacts of routine activities and 

accidental events originating in those adjoining blocks are analyzed here. A full list of the proposed 

stipulation blocks can be found in Appendix D. 

Live bottom habitats are found outside the blocks where the Topographic Features and Live 

Bottom Stipulations have been historically applied. Such habitats are not specifically included in 

those stipulations but are still routinely given protections during NEPA reviews of site-specific 

development plans, as described in NTL 2009-G39, “Biologically-Sensitive Underwater Features and 

Areas.” That NTL provides information and consolidates guidance to help operators understand 

BOEM’s requirements related to sensitive benthic habitats.

Lessees must provide site-specific seafloor survey data and interpretive information 

(including about hard bottom features) with each EP, DOCD, and DPP. Site-specific NEPA reviews 

are conducted on these plans by BOEM’s subject-matter experts on a case-by-case basis to 
Description of the Affected Environment and Impact Analysis 4-163

determine whether a proposed operation could impact a live bottom feature. If an impact is judged 

likely based on site-specific information derived from BOEM’s studies/databases, other published 

research, geohazard survey data, or another creditable source, the operator may be required to 

distance/relocate the proposed operation or undertake other mitigations to prevent an impact. This 

analysis assumes continuation of the protective measures outlined in NTL 2009-G39, as they are 

routinely applied (where appropriate) during all site-specific plan reviews. The Live Bottom 

Stipulation is applied to individual lease sales at the discretion of the Secretary and has been 

consistently applied to the same lease blocks for decades. The types of potential impacts to live 

bottom communities described in this chapter would become more likely and more severe without 

the continued application of these stipulations.

4.6.2.1 Description of the Affected Environment

The terms live bottom and hard bottom are often used interchangeably, but they are actually 

distinct since it is possible to have hard bottom that is not live bottom. Hard substrates can form 

crusts, pavements, pinnacles, ledges, outcrops, and other reefal features (Jenkins, 2011). These 

harder substrates may or may not be covered by a thin veneer of muddy or sandy sediments that 

can be deposited and removed over time by currents and storms. Hard substrates with the lowest 

vertical relief are the most likely to be routinely buried and exposed. Encrusting algae and sessile 

invertebrates regularly attach to and cover exposed hard substrates, creating live bottoms. For the 

purposes of the Live Bottom Stipulation, “live bottom areas” have been defined as communities or 

areas that contain biological assemblages consisting of sessile invertebrates such as sea fans, sea 

whips, hydroids, anemones, ascidians, sponges, bryozoans, or corals living upon and attached to 

naturally occurring hard or rocky formations with rough, broken, or smooth topography; or areas 

whose lithotope (substrate type) favors the accumulation of turtles, fishes, and other fauna.

Distribution of Hard/Live Bottoms in the Gulf of Mexico

The distribution of hard bottoms in the GOM is not fully known, due in part to the patchy and 

ephemeral (temporary) nature of hard bottoms that do not have sufficient vertical relief to avoid 

intermittent sediment burial (Parker et al., 1983; Jenkins, 2011; Simmons et al., 2014; Jaap, 2015). 

Although accurate quantification is challenging and can quickly become outdated, Parker et al. 

(1983) illustrates a reasonable overall proportion and distribution of hard bottoms in U.S. portions of 

the GOM. The study extrapolated from 732 visual sampling stations to roughly approximate the 

amount of hard bottom habitat in a band of relatively shallow waters (18-91 m; 59-299 ft), estimating 

that about 94 percent (44,946 km2

; 17,354 mi2) of the total lies between Key West and Pensacola, 

Florida, on the broad West Florida Shelf, and only about 6 percent (2,780 km2

; 1,073 mi2) lies 

between Pensacola, Florida, and the Rio Grande River, where the continental shelf break is closer to 

shore. More recently, Jenkins (2011) interpolated a Gulfwide estimate of dominant surficial seafloor 

sediments.

Beyond direct sampling and visual observations, an evolving variety of geophysical 

techniques such as sidescan- and multibeam echo sounder-sonar (Hine et al., 2008; Mueller et al., 

2014) and 3D seismic (USDOI, BOEM, 2015c; Chapter 4.4, Deepwater Benthic Communities) can 
4-164 Gulf of Mexico Multisale EIS

also be used to estimate and map the distribution of hard bottom habitats. In the eastern GOM, far 

from the proposed EPA lease sale area and in parts of the EPA currently under a lease moratorium, 

there are several areas (including the Florida Middle Grounds, Madison-Swanson Marine Reserve, 

Steamboat Lumps, the Dry Tortugas Ecological Reserves, and Pulley Ridge, as shown in Figure 

4-17) containing high concentrations of low-relief live bottom habitat. These and other areas have 

been designated by the NMFS and GMFMC as marine reserves and/or EFH Habitat Areas of 

Particular Concern in recognition of the high ecological and socioeconomic (i.e., fisheries) value of 

live bottom habitat (Simmons et al., 2014; Figure 4-17). Designation is intended to encourage 

additional research and (in some but not all cases) implement fisheries management measures such 

as restrictions on gear types (Simmons et al., 2014). However, HAPC designation does not have 

direct bearing on nonfishing activities such as those regulated by BOEM. BOEM does consult with 

the NMFS on EFH and HAPCs, including the above-named areas (Essential Fish Habitat 

Assessment white paper, USDOI, DOEM, 2016d).

Live Bottom Ecology

Live bottom communities are controlled by interconnected abiotic and biotic factors (Brooks, 

1991; Weaver et al., 2002; Jaap, 2015). Physical conditions (e.g., light, sedimentation/turbidity, 

substrate type, temperature, salinity, prevailing currents, and the frequency and intensity of severe 

weather events) affect biological variables such as larval transport, settlement, and growth. For 

example, Lugo-Fernández et al. (2001) reported blockage of coral larval dispersal from the Flower 

Garden Bank area to the eastern GOM by the Mississippi River plume. In addition, biological 

controls, such as predation and trophic interactions, can affect epibenthic community development 

and disturbance response. The relative importance of each controlling factor varies for different 

types of epibenthos (Jaap, 2015).

A persistent nepheloid layer (a layer of sediment-laden water above the seafloor) can be a 

controlling factor for live bottom species sensitive to turbidity (Rezak et al., 1990) and thus is also 

relevant to impact-producing factors of some OCS oil- and gas-related activities. This layer reduces 

the light reaching hard bottoms, resulting in decreased species richness and abundance below 

262 ft (80 m) (Dennis and Bright, 1988; Rezak et al., 1990). Some studies suggest that the 

Mississippi River plume influences the distribution and abundance of sessile invertebrates within 

43 mi (70 km) of the river delta and may affect turbidity and sedimentation throughout the Pinnacle 

Trend (Gittings et al., 1992a; CSA and GERG, 2001). Nepheloid layers are less frequent in the 

eastern GOM, but they can occur when the Mississippi River plume and upwelling affect the area 

(CSA and GERG, 2001).

Large, shallow-water coral reefs created via biogenic deposition of calcium carbonate over 

time by hermatypic coral species (refer to Schumacher and Zibrowius [1985] for more information 

about theoretical and practical definitions of “hermatypic”) are present only at the southern end of the 

EPA and on a few topographic features in the WPA and CPA (refer to Chapter 4.6.1, Topographic 

Features, for the impact analysis). While the general public often thinks of such biogenic coral reefs 

as the only natural habitat for corals, Jaap (2015) illustrates that, for most of their geological history, 
Description of the Affected Environment and Impact Analysis 4-165

corals have existed in less elaborate epibenthic communities that are not built upon large biogenic 

reefs (Veron, 1995 and 2000). These types of corals and epibenthic communities are the focus of 

this chapter on pinnacles and low-relief features.

The Pinnacle Trend Area

Physical Characteristics

The Pinnacle Trend is an approximately 64 x 16 mi (103 x 26 km) area in water depths of 

about 200-650 ft (60-200 m). It is in the northeastern portion of the CPA at the outer edge of the 

Mississippi-Alabama shelf, between the Mississippi River and De Soto Canyon (Figures 4-17 and 

4-19A).

Live bottoms within the Pinnacle Trend consist of both high-relief outcroppings at the edge of 

the Mississippi-Alabama Shelf and low-relief hard bottoms on the inner and middle shelf. BOEM has 

sponsored numerous studies providing information about these features (Brooks, 1991; CSA, 1992; 

Thompson et al., 1999; CSA and GERG, 2001). A 2002 bathymetric survey by the USGS (Gardner 

et al., 2002) provided high-quality seafloor imagery that has become the baseline for this area 

(Figure 4-19B).

The eastern part of the Pinnacle Trend is covered with a thin, well-sorted layer of fine- to 

medium-grained quartzose sand originating from eastern continental rivers. The western portion is 

covered with fine silts, sands, and clays deposited by the Mississippi River (CSA, 1992). The linear 

orientation and distribution of some features correspond with depth contours and may represent 

historic shorelines and drowned calcareous biogenic reefs that developed prior to the most recent 

sea-level rise (Ludwick and Walton, 1957; Sager et al., 1992; Thompson et al., 1999).

The high-relief features are complex in shape and structure (e.g., Figure 4-19C) and provide 

varied zones of microhabitat for attached organisms. High-relief features consist of pinnacles, flattop reefs, reef-like mounds, patch reefs, and ridges and scarps. Tall spire-like mounds are the 

historical “pinnacles” for which the region is named. The pinnacles rise up to 66 ft (20 m) in height 

and can be over 1,640 ft (500 m) in diameter (Thompson et al., 1999; Brooks, 1991). Other features 

in this area are smaller and have less vertical relief, but they are more numerous. Low-relief 

features include fields of small seafloor mounds that rise only a meter or two above the seafloor but 

still provide hard surfaces for attached epifauna. Fields of shallow depressions about 3-20 ft (1-6 m) 

across also add habitat complexity to the overall character of the Pinnacle Trend area.
4-166 Gulf of Mexico Multisale EIS

Figure 4-19. General Location of the Pinnacle Trend (A), Multibeam Bathymetry and 

Named Reef Areas (B), and an Exaggerated Vertical Relief Profile of Rough 

Tongue Reef (C). (Figure parts were excerpted and rearranged from Gardner 

et al., 2002.)
Description of the Affected Environment and Impact Analysis 4-167

Ecology of Live Bottom Communities in the Pinnacle Trend

The substantial amount of hard substrate in the Pinnacle Trend supports colonization by 

large numbers of suspension-feeding invertebrates, including octocorals, black corals, and sponges, 

and over 70 species of fish (Weaver et al., 2002). The Pinnacle Trend features are composed of 

carbonate reef material (Ludwick and Walton, 1957) and vary in shape, size, vertical relief, and 

overall complexity. These physical characteristics affect the composition (e.g., biodiversity, density, 

etc.) of the community associated with the substrate. Generally, the more complex the topographic 

shape of the substrate, the greater the variety of habitats for organisms and thus greater abundance 

and diversity of organisms.

Assemblages of coralline algae, sponges, octocorals, crinoids, and bryozoans are present at 

the tops of the shallowest features in water depths of less than 230 ft (70 m) (CSA, 1992). On the 

deeper features, as well as along the sides of the shallower pinnacles, ahermatypic corals may be 

locally abundant, along with octocorals, crinoids, and basket stars. The diversity and abundance of 

the associated species appear to be related to the size and complexity of the features, with the 

lower-relief outcrops typically having lower faunal densities and higher relief features having more 

diverse faunal communities (Gittings et al., 1992a; Thompson et al., 1999).

Low-Relief Live Bottoms

Outside of the Pinnacle Trend, low-relief live bottom features can and do occur in isolated 

locations in shallow waters (<984 ft; 300 m) throughout the GOM, wherever there is suitable hard 

substrate and other physical conditions (depth, turbidity, etc.) allow for epibenthic community 

development (Rezak et al., 1990). However, they are primarily known to be present in some 

locations on the Mississippi-Alabama Shelf and many more locations on the West Florida Shelf 

(Figure 4-17), far east of the proposed EPA lease sale area. None of the blocks with known 

concentrations of live bottom low-relief habitat are expected to be offered for lease; however, several 

live bottom low-relief areas are adjacent to blocks that would be offered for lease under a proposed 

action and could potentially be affected by impacts of routine activities and accidental events. 

Therefore, an analysis of the potential impacts is included in this Multisale EIS.

Ecology of Inner- and Middle-Shelf Live Bottoms of the Mississippi-Alabama Shelf

These nearshore, hard bottom areas are located in 60-130 ft (18-40 m) of water. A finegrained quartz sand sheet covers most of the Mississippi-Alabama Shelf; however, numerous hard 

bottoms that are formed of sedimentary rock occur off the Mississippi River Delta and seaward of the 

Chandeleur Islands (Schroeder, 2000). These features include isolated low-relief, reef-like 

structures; rubble fields; low-relief flat rocks; limestone ledges; rocky outcrops off Mobile Bay; and 

clustered reefs (Schroeder et al., 1988; Schroeder, 2000). Hard bottom features on the MississippiAlabama-Florida Shelf typically provide reef habitat for tropical organisms, including sessile epifauna 

(i.e., soft corals, ahermatypic hard corals, sponges, bryozoans, and crinoids) and fish. 
4-168 Gulf of Mexico Multisale EIS

Various live bottom areas of the Mississippi-Alabama Shelf have been described in literature 

(Shipp and Hopkins, 1978, Schroeder et al., 1988; Schroeder et al., 1989, Brooks, 1991). These 

areas support a number of foundational species (including hard and soft corals, coralline algaes, and 

sponges) that are associated with larger, diverse communities of mobile invertebrates and fishes.

Ecology of Inner- and Middle-Shelf Live Bottoms of the West Florida Shelf

The majority of low-relief live bottom habitats in the GOM are found on the West Florida 

Shelf. The shelf is a relatively flat table of carbonate limestone that is largely covered with carbonate 

sand sheets. BOEM has designated blocks on the West Florida Shelf out to the 100-m (328-ft) 

isobath as Live Bottom (Low-Relief) Stipulation blocks (Figure 4-17) because live bottom 

communities are widely scattered across the West Florida Shelf on limestone ledges and outcrops 

(Jaap, 2015). In many places, the sand frequently shifts due to seasonal storms, occasionally 

uncovering patches of hard bottom. The nepheloid layer found throughout much of the northern 

CPA is not present to the same degree on the West Florida Shelf.

In addition to the smaller, widely distributed low-relief hard bottoms, there are also areas with 

permanently exposed, higher relief hard bottoms. In the southeastern portion of the GOM, shallowwater hermatypic corals are common throughout the Florida Keys reef tract, the Dry Tortugas, and 

Pulley Ridge (Jaap, 2015). To the north along the West Florida Shelf are several other important 

areas recognized by the NMFS/GMFMC (Simmons et al., 2014). Some of these areas are thought 

to be relic reef formations that were “drowned” with historic sea-level rises.

Various sessile fauna and flora develop on exposed surfaces of low-relief hard substrates 

(Jaap, 2015). Some fauna, such as gorgonian soft corals, are flexible and tall enough to survive 

partial sediment burial. Many of the formations have deep reef communities with soft corals, black 

corals, sponges, sea whips/sea fans, anemones, and associated mobile echinoderms and 

crustaceans. Habitats that are sufficiently close to the water surface can support some hermatypic 

corals. Scleractinian and milleporian corals are common on rocky outcrops throughout the eastern 

GOM (Jaap, 2015).

Consultations

In 2014, 20 new coral species were listed as “threatened” under the ESA; all but 7 of these 

are found only in Indo-Pacific waters (Federal Register, 2014b). Three of the new species and two 

others that were previously listed (elkhorn and staghorn) are found in shallow waters of the GOM. 

Some are found on a few topographic features in the WPA/CPA and others in the Dry Tortugas and 

Florida reef tract. These coral species are further described in Chapter 4.9.5. The OCS lease 

blocks in the EPA near these areas are not being offered in a proposed lease sale due to the current 

leasing moratorium and are therefore too distant to be reasonably affected by routine activities or 

accidental events occurring in leased areas. Currently, only staghorn and elkhorn coral have had 

critical habitat areas defined off the Florida Keys and Florida reef tract. For ESA-listed coral found in 

the WPA and CPA where accidental impacts might be possible, these coral species would be 

expected to experience the same impacts as other live bottom organisms. However, due to their 
Description of the Affected Environment and Impact Analysis 4-169

relatively low population sizes, any impacts from accidental events on ESA-listed corals would have 

a magnified effect on each of those species. BOEM consults on listed corals as part of the Section 7 

consultation with the NMFS. Adherence to recommendations resulting from this consultation and 

application of the Live Bottom Stipulation should decrease any impacts to these species.

4.6.2.2 Environmental Consequences 

Routine Activities

A number of routine OCS oil- and gas-related impact-producing factors may cause adverse 

impacts on live bottom communities. As noted above, some factors with minimal impacts are 

presented in greater detail in other chapters and are not repeated here. The potential routine 

impact-producing factors on live bottom habitats analyzed here are grouped into two main categories 

having similar impacts: (1) bottom-disturbing activities (e.g., anchoring, infrastructure emplacement 

and removal, and core sampling); and (2) drilling-related sediment and waste discharges (e.g., 

drilling muds and cuttings, and produced waters). These impact-producing factors have the potential 

to damage live bottom habitats and disrupt associated communities if not sufficiently distanced via 

mitigations.

Bottom-disturbing activities can be described as any activities that result in the physical 

disturbance of the seafloor during the exploration, production, or decommissioning phase of OCS oiland gas-related operations. Anchoring, operational wastes produced during drilling, trenching, pipelaying, and structure emplacement and removal are examples of OCS oil- and gas-related activities 

that disturb the seafloor (refer to Chapter 3.1). The spatial extent of the seafloor disturbance and 

the magnitude of the effect on benthic organisms would depend on the specific activity, local 

environmental conditions (e.g., currents, water depth, etc.), and species-specific behaviors and 

habitat preferences.

Drilling of new wells is one of the activities with the greatest impact potential, due to the 

associated sedimentation/turbidity caused by the drilling process and from the release of drilling 

cuttings and discharges. As noted in Chapter 3, drilling an exploratory well produces approximately 

2,000 metric tons of combined drilling fluid and cuttings, though the total mass may vary widely for 

different wells (Neff, 2005). Cuttings discharged at the surface tend to disperse in the water column 

and are distributed at low concentrations (CSA, 2004). In deep water, the majority of cuttings 

discharged at the sea surface are likely to be deposited within 820 ft (250 m) of the well (CSA, 

2006). Cuttings shunted to the seafloor forms piles concentrated within a smaller area than when 

sediments are discharged at the sea surface (Neff, 2005).

Turbidity from suspended sediments, along with sediment displacement resulting from 

routine, bottom-disturbing OCS oil- and gas-related activities generally have localized effects. In 

general, impacts to live bottoms could include any or all of the following: reduced settlement and 

growth due to loss of available hard substrate; inhibited feeding leading to reduced reproductive 

fitness; and mortality of individuals (e.g., coral polyps) and groups (e.g., a coral colony). Reductions 

in overall biological cover could have secondary ecological effects on organisms that were using the 
4-170 Gulf of Mexico Multisale EIS

complex structural microhabitats. Some mobile invertebrates (e.g., star fish) are expected to be able 

to move to avoid the heaviest sedimentation and highest suspended sediment loads within 33 ft 

(10 m) of a disturbance, while sessile invertebrates (e.g., corals) cannot. Both sessile and mobile 

invertebrate species adapted to living in turbid environments, such as those commonly found in the 

persistent nepheloid layer or otherwise adapted to occasional sediment inundation, may be less 

affected by increased turbidity. Such organisms may be adapted to remove some covering 

sediment via tentacle motion and mucus secretion (Shinn et al., 1980; Hudson and Robbin, 1980). 

Other species that typically inhabit less turbid waters would suffer greater impacts (Rogers, 1990; 

Gittings et al., 1992a). For example, zooxanthellate coral species are dependent on a continuous, 

unobscured light source to support the symbiotic photosynthetic algae (zooxanthellae) and may 

suffer coral bleaching if the water column becomes overly turbid. Solitary octocorals and gorgonians 

are generally more tolerant of sedimentation, partly because they grow tall and are flexible, reducing 

sediment accumulation and allowing for easier removal (Marszalek, 1981; Torres et al., 2001; 

Gittings et al., 1992a). Apart from turbidity and sedimentation, the chemical content of drilling muds 

and cuttings, and to a lesser extent produced waters, is another potential impact-producing factor 

since these may contain hydrocarbons, trace metals including heavy metals, elemental sulfur, and 

radionuclides (Kendall and Rainey, 1991; Trefry et al., 1995). Substances containing heavy metals 

and other potentially toxic compounds would have the potential to be moderately toxic to live bottom 

organisms, but only if they were to come into contact in undiluted strengths (CSA, 2004). Although 

the literature has not reported impacts corals as a result of exposure to contaminants in cuttings, 

infauna have shown effects at distances <330 ft (<100 m) from the discharge. These include 

reduced reproductive fitness, altered populations, and acute toxicity (Montagna and Harper, 1996; 

Carr et al., 1996; Kennicutt et al., 1996; Hart et al., 1989; Chapman et al., 1991; CSA, 2004). 

Because of BOEM’s distancing requirements for new wells, contact with concentrated (and 

potentially harmful) levels of any such toxins is not expected. Produced waters (refer to Chapter 

3.1.5.1.2 for more detail) are rapidly diluted with distance, and impacts are generally only observed 

within very close proximity of the discharge point (Gittings et al., 1992a; Neff, 2005). In addition to 

the protection offered by BOEM’s distancing requirements, releases of toxic discharges are 

regulated by the USEPA through the issuance of NPDES permits. Adherence to these regulations 

would help ensure that water quality is maintained at nontoxic levels.

In addition to drilling activities, the process of installing and removing OCS oil- and gasrelated infrastructure (i.e., pipelines, platforms, and subsea systems including cables) also has the 

potential to displace large volumes of sediment. The resulting localized increases in turbidity and 

sedimentation would have the same indirect impacts as those caused by drilling-related sediment 

discharges.

The OCS oil- and gas-related infrastructure/equipment also has the potential to damage or 

kill benthic organisms should the equipment itself make direct contact. Any object placed on or 

through a live bottom feature can cause partial or complete breakage, crushing, or smothering. In 

addition to mortality, there could be any or all of the potential sublethal impacts already described 

above in relation to sedimentation. The severity of impacts from direct physical contact would vary 

in direct proportion to the surface area and mass of the specific equipment. For example, the 
Description of the Affected Environment and Impact Analysis 4-171

placement of a large bottom-founded platform on a live bottom would have a much greater impact 

than the placement of a small umbilical cable.

Similarly, anchor damage is one of the greatest threats to the biota of the offshore banks in 

the GOM (Rezak and Bright, 1979; Rezak et al., 1985; Gittings et al., 1992a; Hudson et al., 1982). 

Anchors may break, fragment, or overturn corals, sponges, and other benthic organisms, and the 

anchor chain or cable may drag across and shear organisms off the substrate (Dinsdale and 

Harriott, 2004). This would result in negative consequences ranging from increased stress to 

mortality (Dinsdale and Harriott, 2004). The impact of dragging an anchor across a live bottom 

would depend on the distance and duration of bottom contact, but it could be considerable due to the 

forces involved. Dragged anchors often leave seafloor scars noticeable on sidescan-sonar imagery 

years later. Damage to a coral community may take 10 or more years to recover (Fucik et al., 1984; 

Rogers and Garrison, 2001).

As further detailed in other chapters, explosive severance methods used during 

decommissioning activities could result in damage or death to any organisms within the vicinity of 

the blast or associated sediment plume, although long-term turbidity is not expected from platform 

removal operations. The shockwave from the blast could also damage or destroy the underlying 

hard substrates required to support live bottoms. The BSEE Interim Policy Document 2013-07, 

“Rigs-to-Reefs Policy,” specifies that the use of explosive severance methods will not be approved if 

analysis determines they would cause harm to established artificial reef sites and/or natural live 

bottoms.

Potential impacts resulting from all of the above routine activities are mitigated through the 

Live Bottom Stipulation and the protective measures summarized above and detailed in NTL 2009-

G39. The site-specific survey information and distancing requirements described in NTL 2009-G39 

would allow BOEM to identify and protect live bottom features from harm by proposed OCS oil- and 

gas-related activities during postlease reviews. If those protective measures are applied to identified 

live bottom habitats as expected, at the scope of this analysis, impacts of routine activities would be 

expected to be negligible. 

Without adherence to the requirements of the stipulation and external regulatory restrictions 

on discharges, impacts to live bottom communities from the above routine activities could rise to 

minor, moderate, or even major, depending on the number and locations of specific activities. The 

highest impact levels are possible in the improbable (but theoretically possible) case that a large 

number of routine activity disturbances were to physically impact a large number of live bottom 

habitats. Even without mitigations, the likelihood is very low that a large number of OCS oil- and 

gas-related activities would occur in close proximity because the hard substrate habitats supporting 

live bottom communities are patchily distributed throughout the GOM and are relatively rare 

compared with soft bottom substrates. But this possibility cannot be definitively ruled out without 

knowing the precise spatial distribution of both future OCS oil- and gas-related activities and live 

bottom communities.
4-172 Gulf of Mexico Multisale EIS

Accidental Events

The primary accidental impact-producing factors on live bottoms analyzed here are grouped 

into two categories: (1) bottom-disturbing activities (e.g., anchoring and infrastructure emplacement 

and removal); and (2) oil spills (surface and subsurface) and associated cleanup responses. These 

impact-producing factors have the potential to damage live bottom habitats and disrupt associated 

communities if not sufficiently distanced or otherwise mitigated.

Bottom-Disturbing Activities

Impacts resulting from bottom-disturbing activities were detailed under “Routine Activities” 

and are largely the same for accidental events. There are only slight differences that need to be 

considered here; these differences are related to mechanisms and potential severity. The primary, 

accidental bottom-disturbing activity is the inadvertent deposition or placement of equipment on live 

bottoms. Accidental loss of equipment could occur during transfer operations between vessels and 

platforms, during vessel transit, during an “on deck” accident, as a consequence of a severe storm, 

or if a structure, drill, or anchor is unintentionally placed in the wrong location during operations. 

During routine operations, distancing mitigations offer some protections against these types of 

impact, but those protections do not apply to accidents, other than to reduce the likelihood of routine 

activities occurring in live bottom areas in the first place. Any object placed on or through a live 

bottom feature can cause partial or complete breakage, crushing, or smothering of both substrate 

and organisms, and/or could cause increased sedimentation as equipment disturbs the seafloor. In 

addition to mortality, live bottom communities could experience any or all of the potential sublethal 

impacts already described in the “Routine Activities” section above. The severity of impacts from 

direct physical contact would vary in direct proportion to the surface area and mass of the specific 

equipment. Given the relative rarity of live bottom habitats and communities in the GOM, impacts 

from accidental bottom-disturbing equipment are expected to be infrequent and highly localized, with 

the likelihood of accidental contact further reduced by the expected distancing mitigations. However, 

because of the unplanned and potentially uncontrolled nature of accidental bottom-disturbing events, 

there exists greater uncertainty about their potential impact severity than exists for planned routine 

activities. Therefore, at the scale of this analysis, impacts to deepwater benthic communities could 

range from negligible to minor, depending on their overall frequency and severity and whether or 

not community-level impacts as a result of accidental events can be clearly distinguished from 

natural variation.

Without the protective measures provided by the Live Bottom Stipulation and by postlease 

reviews and distancing, the potential impacts of accidental bottom disturbances could rise to 

moderate or even major levels, in the improbable (but theoretically possible) case that a large 

number of accidental disturbances were to physically impact a large number of deepwater benthic 

communities. Even without mitigations, the likelihood is very low that a large number of OCS oiland gas-related activities would occur in close proximity to the relatively rare hard substrate habitats 

supporting live bottom communities, but this possibility cannot be definitively ruled out without 

knowing the precise spatial distribution of both future OCS oil- and gas-related activities and live 

bottom communities.
Description of the Affected Environment and Impact Analysis 4-173

Oil Spills and Associated Impacts

Oil spills, historic trends, the characteristics of oil, and factors affecting the fate of oil 

released into the marine environment are discussed in detail in Chapter 3.2.1, and the potential 

effects on water quality are analyzed in Chapter 4.2 (Water Quality). For information on impacts 

specifically resulting from a catastrophic oil spill (beyond the scope of this analysis), refer to the 

Catastrophic Spill Events Analysis white paper (USDOI, BOEM, 2016c).

Impacts related to an accidental release of oil or other contaminants could adversely affect 

live bottom communities. Potential impacts related to an accidental spill would depend on the 

combination of these various components: surface oil; subsurface oil; chemical dispersants and 

dispersed oil; sedimented oil (oil adsorbed to sediment particles, also known as “marine snow”); 

sedimentation caused by a loss of well control; and certain spill-response activities. Adherence to 

well-distancing requirements should serve to reduce such impacts.

Biological impacts resulting from exposure to accidentally released oil droplets and/or 

chemical dispersants are anticipated to be mostly sublethal. Sublethal impacts that may occur to 

exposed corals and similar benthic invertebrates may include reduced feeding, reduced 

photosynthesis, reduced reproduction and growth, physical tissue damage, and altered behavior. 

For example, short-term (24 hours) sublethal responses of one coral species included mesenterial 

filament extrusion, extreme tissue contraction, tentacle retraction, and localized tissue rupture after 

exposure to dispersed oil at a concentration of 20 ppm (Knap et al., 1983; Wyers et al., 1986). It is 

important to note that, generally, laboratory experimental concentrations are designed to discover 

toxicity thresholds (e.g., DeLeo et al., 2015) that exceed probable exposure concentrations in the 

field.

Oil spills originating at the surface, such as from a vessel or platform, have some potential to 

impact live bottom features. The depth of OCS live bottom features helps to buffer and protect such 

features from most surface spills because their crests are generally deeper than the physical mixing 

ability of surface oil (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002; 

Thompson et al., 1999; Schroeder, 2000). Oil becomes diluted as it physically mixes with the 

surrounding water column. The shallowest known concentrations of live bottom features occur in the 

Live Bottom (Low Relief) Stipulation blocks, which are not expected to be offered for lease. In the 

Pinnacle Trend area, the largest features rise to within 130 ft (40 m) of the sea surface, but other live 

bottom features (except for named topographic features) have less relief or are found in deeper 

waters. In very unusual conditions, surface oil could contact Pinnacle Trend features. Silva et al. 

(2015) documented acute lethal and sublethal impacts to gorgonians on Pinnacle Trend features 

caused by large amounts of Deepwater Horizon-sourced surface oil. A large volume of 

oil/dispersant mixture was submerged by unusually strong wave action associated with a tropical 

storm that passed directly over the oil. As a result, sizable amounts of the relatively undiluted 

oil/dispersant reached live bottom features. This contact, though demonstrably possible, required an 

unusual combination of atypical conditions, making it generally unlikely outside of a catastrophic spill 

situation, which is not part of a proposed action and not likely expected to occur.
4-174 Gulf of Mexico Multisale EIS

In a subsurface spill or loss of well control situation, it is expected that the majority of 

released oil would rise quickly to the surface due the characteristics of northern GOM oil reserves, 

meaning most impacts would be similar to a surface-originating spill. However, if an oil spill/loss of 

well control occurs at great depths and released oil is subjected to higher water pressures, some oil 

droplets may emulsify and become entrained deep in the water column (Boehm and Fiest, 1982), 

creating a subsurface plume (Adcroft et al., 2010). Such plumes were documented following the 

Deepwater Horizon oil spill. If a concentrated plume came into contact with live bottom organisms, 

impacts could include mortality, failed reproductive success, reduced biodiversity, reduced coverage 

of fauna and flora on hard substrates, and changes in community structure (Reimer, 1975; Guzmán 

and Holst, 1993; Negri and Heyward, 2000; Silva et al., 2015). Exact impacts would depend on the 

location, age of the spill, and the hydrographic characteristics of the area (Bright and Rezak, 1978; 

Rezak et al., 1983; McGrail, 1982; Le Henáff et al., 2012). However, because shallow-water live 

bottom features are located on the shelf and upwelling events are limited to hurricanes, eddy 

formations, or when certain metrological conditions exist (Walker, 2001; Collard and LugoFernandez, 1999; Zavala-Hidalgo et al., 2006), contact of a subsurface plume with a live bottom 

feature would only occur under the most ideal conditions (e.g., Silva et al., 2015).

The USCG may allow the use of chemical dispersants in certain spill situations. Chemical 

dispersion of oil can help to break up concentrations of oil and accelerate natural weathering 

processes and bacterial biodegradation. Use of dispersants may, however, allow surface oil to 

penetrate to greater depths than normally expected from typical physical mixing, and dispersed oil 

might tend to remain further below the water’s surface than undispersed oil (McAuliffe et al., 1981b; 

Lewis and Aurand, 1997). Reports about dispersant usage on surface plumes indicate that a 

majority of the dispersed oil remains in the top 33 ft (10 m) of the water column, which is generally 

shallower than the crests of OCS live bottom features; therefore, contact is generally not expected 

apart from unusually ideal conditions such as those seen in Silva et al. (2015). If contact is made, 

impacts may differ somewhat between oil, oil/dispersant mixtures, and dispersant alone. DeLeo 

et al. (2015) demonstrated that concentrated amounts of dispersant and oil/dispersant mixtures 

caused more severe health declines to live bottom organisms than oil-only mixtures. One field study 

(Yender and Michel, 2010) indicated less severe impacts, possibly due to that study’s (more 

realistic) application of dispersants in an open field system, although during the Deepwater Horizon

oil spill, dispersants were applied subsea at the source of the blowout. Stratified density layers of 

water allowed the oil/dispersant plume to remain at depth instead of dispersing up into the water 

column (Joint Analysis Group, 2010), and these concentrated plumes are thought to have caused 

serious but fairly localized damage to deepwater corals on the continental slope (White et al., 2012; 

Hsing et al., 2013; Fisher et al., 2014a). It is unlikely that concentrated oil/dispersant mixtures would 

be found near shallow-water live bottom features; therefore, lethal exposures to large numbers of 

shallow-water live bottom organisms are not anticipated.

For any accidental spill, it is expected that a certain quantity of oil may eventually settle on 

the seafloor through a binding process with suspended sediment particles (adsorption) or after being 

consumed and excreted by phytoplankton (Passow et al., 2012). The product of these processes is 

sometimes referred to as “marine snow.” It is expected that the greatest amount of adsorbed oil 
Description of the Affected Environment and Impact Analysis 4-175

particles would occur close to the spill, with the concentration reducing over distance. If the spill 

occurs close to a live bottom feature, some underlying live bottom organisms may become 

smothered by the particles and experience long-term exposure to hydrocarbons. This was seen for 

some deepwater corals following the Deepwater Horizon oil spill and response (White et al., 2012; 

Hsing et al., 2013; Fisher et al., 2014a). Beyond the localized area of impact in that case, particles 

would become increasingly biodegraded and dispersed. Localized impacts to live bottom organisms 

would be expected to be largely sublethal and could include reduced recruitment success, reduced 

growth, and reduced biological cover as a result of impaired recruitment (Rogers, 1990; Kushmaro 

et al., 1997).

Sediments suspended or displaced as a result of a loss of well control could also impact live 

bottom organisms. These impacts would be largely identical to those caused by sedimentation 

stirred up by bottom-disturbing equipment, with the possible addition of toxic hydrocarbons or drilling 

muds in the sediments (refer to “Routine Activities”). Because OCS-permitted wells would have 

been distanced from live bottom features before installation, it is expected that the heaviest sediment 

concentrations would fall out of suspension and disperse before reaching sensitive live bottom 

features, preventing most impacts. Some live bottom organisms, such as flexible sea fans, are 

naturally adapted to turbid conditions and may not be as negatively affected. Outside of a 

catastrophic spill situation, a very substantial amount of sediment burial of organisms during an 

accidental spill event is not reasonably foreseeable (refer to the Catastrophic Spill Events Analysis

white paper, USDOI, BOEM, 2016c).

Finally, spill cleanup/response activities could themselves have negative. During a response 

operation, the risk of accidental impacts of bottom-disturbing equipment is increased. There could 

be unplanned or emergency anchoring on live bottom features or accidental losses of heavy 

equipment from responding vessels. Response-related equipment such as seafloor-anchored 

booms may be used and could inadvertently contact live bottom organisms. In addition, drilling 

muds may be pumped into a well to prevent a loss of well control. It is possible that during this 

process, some of this mud may be forced out of the well and deposited on the seafloor near the well 

site. If this occurs, the impacts would be severe for any organisms buried; however, the impact 

beyond the immediate area would be limited and adherence to the original distancing requirements 

would prevent or reduce most impacts.

Accidental spills have historically been small and are low-probability events (Table 3-12). 

While the total amount of hard/live bottoms in the GOM is small compared with soft bottoms, the 

habitats are widely distributed and a localized impact from one noncatastrophic accidental event 

would only impact a small portion of the overall resource (McEachran, 2009).

All of the above impact-producing factors could lead to lethal or sublethal impacts on 

individual live bottom communities, with the range of impacts dependent on the quantity of spilled oil 

and proximity to habitats. While a spill resulting from a catastrophic-level blowout in deep water 

(such as the Deepwater Horizon oil spill) has the potential to seriously impact individual live bottom 

communities over a long time period, such a spill is not reasonably foreseeable as a result of a 
4-176 Gulf of Mexico Multisale EIS

proposed action. Impacts from individual routine activities and reasonably foreseeable accidental 

events are usually temporary, highly localized, and expected to impact only small numbers of 

organisms and substrates at a time. Some live bottom species possess natural adaptations to highturbidity environments that could help remove spill-related sediments. Moreover, use of the 

expected site-specific plan reviews/mitigations would distance activities from identified live bottom 

communities, greatly diminishing the likelihood and severity of potential effects. Therefore, at the 

scale of this analysis, and with application of the expected mitigation practices, impacts on live

bottom communities from accidental spills and associated impact-producing factors are expected to 

range from negligible to minor. This range of potential impact levels reflects the relative 

uncertainty associated with unplanned and potentially uncontrolled accidental spills. The exact 

impact would depend on the overall frequency and severity of accidental spills, their proximity to live 

bottoms, and whether or not community-level impacts as a result of accidental events can be clearly 

distinguished from natural variation.

Without the protective measures provided by the Live Bottom Stipulation and associated 

postlease reviews and distancing, the potential impacts of accidental spills could rise to moderate or 

even major levels, in the improbable (but theoretically possible) case that a large number of 

accidental spills were to occur at wells in close proximity to a large number of live bottom 

communities. Even without mitigations, the likelihood is very low that a large number of accidental 

spills would occur in close proximity to the relatively rare hard substrate habitats supporting live 

bottom communities, but this possibility cannot be definitively ruled out without knowing both the 

precise distribution of such spills and live bottom communities. 

Cumulative Impacts

The following analysis considers whether the incremental impacts of routine activities and 

accidental events associated with the proposed OCS Oil and Gas Program-related operations, when 

added to or acting synergistically with existing non-OCS oil- and gas- related impact sources from 

the cumulative impacts scenario, may result in a significant collective impact.

OCS Oil- and Gas-Related Impacts

The OCS oil- and gas Program-related impacts include the long-term, incremental 

contribution of the routine and accidental bottom-disturbing activities outlined above: (1) bottomdisturbing activities (e.g., drilling, anchoring, infrastructure installation/removal, and associated 

sedimentation); (2) sediment and waste discharges (e.g., drilling muds and cuttings, and produced 

waters); and (3) oil spills (surface and subsurface and associated cleanup responses). As already 

detailed, these impact-producing factors have the potential to damage individual live bottom habitats 

and disrupt associated benthic communities, if insufficiently distanced or otherwise mitigated. 

Bottom-disturbing activities could result in the physical destruction of benthic habitat and organisms 

or the disturbance of sediments within the environment, resulting in burial and/or increased turbidity. 

Routine and accidental waste discharges could be toxic if contacted in undiluted form near the 

source. Oil spills and dispersants are known to have negative, acute effects on benthic organisms, 

and the cumulative, long term effects of persistent, low-level exposure to oil are not yet fully 
Description of the Affected Environment and Impact Analysis 4-177

understood. All of these activities could lead to lethal or sublethal impacts on individual live bottom 

communities. However, impacts from individual events are usually temporary, highly localized, and 

expected to impact only small numbers of organisms and substrates at a time, particularly since live 

bottom habitats are relatively rare and distributed in only small patches of the OCS areas that are 

anticipated to be leased. Also, adherence to the expected Live Bottom Stipulation and site-specific 

plan reviews/mitigations would distance many of these activities, greatly diminishing potential 

effects. Therefore, the incremental cumulative contribution of these proposed OCS oil- and gasrelated activities is expected to have only negligible impacts.

Non-OCS Oil- and Gas-Related Impacts

The cumulative, long-term impact of reasonably foreseeable, non-OCS oil- and gas-related 

anthropogenic activities and influential environmental conditions on live bottoms could be 

considerable, although they are difficult to precisely quantify when projecting future conditions over 

the next 50 years. The primary anthropogenic activities with impact producing factors are vessel 

anchoring and fishing. The primary environmental factors are invasive species, hypoxia, severe 

weather, and climate change. There is extensive scientific literature available about all of these 

subjects; only a brief summary analysis is provided here. It should be noted that BOEM’s 

stipulations and site-specific plan reviews/mitigations are designed to protect live bottom resources 

from OCS oil- and gas-related activities within BOEM’s jurisdiction and to mitigate against a 

proposed action’s incremental cumulative impact contribution to the overall OCS and non-OCS 

cumulative impacts

Certain fishing gear and overfishing can have long-term effects on benthic species and 

habitats. These effects can be caused both by the gear and through indirect trophic effects. 

Bottom-tending gear such as bottom trawls and bottom-contacting long lines could destroy or disturb 

hard/live bottoms such that species diversity and abundance are negatively affected (Wells et al., 

2008; NRC, 2014; Pusceddu et al., 2014; Secor et al., 2014). This impact may dislodge, entangle, 

or otherwise damage organisms inhabiting live bottoms. Large emergent sponges and corals may 

be particularly vulnerable to trawling activity, as these organisms grow above the substrate and can 

be caught and removed by trawling activity (Freese et al., 1999, Hourigan 2014). Because many 

hook-and-line fishermen target live bottom-associated reef fish, they may use bottom-contacting 

gear that can damage the tissues of benthic organisms, particularly when the line is snagged and 

abandoned. In addition, fishing pressure could selectively alter fish community structure and, over 

the long term, have a top-down trophic impact on fish populations that interact with live bottoms.

The impacts of vessel anchoring on live bottoms are similar to the other bottom-disturbing 

impacts described above. Of note in this section is that smaller vessels such as recreational fishing 

and diving boats are also included. Such vessels are more numerous than large vessels, though 

their individual anchors are much smaller and most recreational activities occur close to shore. The 

degree of potential damage is dependent on the size of the anchor and chain (Lissner et al., 1991). 

Anchor damages to benthic organisms such as corals may take more than 10 years to recover 

(Fucik et al., 1984; Rogers and Garrison, 2001).
4-178 Gulf of Mexico Multisale EIS

The lionfish (Pterois volitans/miles) is an invasive species of concern that has been reported 

throughout the GOM (USDOI, GS, 2010 and 2015; Johnston et al., 2013; Aguilar-Perera and 

Tuz-Sulub, 2010). This fish is thought to drive down diversity and abundance of benthic organisms, 

especially crabs, demersal fishes, and shrimps (Green et al., 2012). The cumulative impact of 

invasive species on GOM live bottom features is unknown at this time, but it is projected that 

negative impacts are likely to worsen over time as lionfish populations are increasing exponentially 

in both abundance and distribution (Switzer et al., 2015).

Depleted dissolved oxygen occurs seasonally in shelf waters of the northern GOM, including 

in areas with live bottoms. Dissolved oxygen depletion is caused primarily by the decomposition of 

algae whose production is stimulated by excess nutrients delivered by the Mississippi River and 

other coastal rivers, the source of which can be traced back to onshore human activities such as 

fertilizer use. Hypoxic (dissolved oxygen ≤2.0 mg/L) conditions can have lethal and sublethal effects 

on aquatic organisms (refer to Chapter 3.3.2.12 for more information on hypoxia). Although hypoxic 

conditions are mainly a characteristic of Louisiana-Texas shelf waters, negative effects could reach 

some live bottom (low-relief) communities in the northeast portion of the CPA. Dramatic changes in 

natural levels of dissolved oxygen over time could alter the composition and distribution of live 

bottom communities.

Severe weather events of sufficient magnitude (e.g., hurricanes) may also cause impacts. 

The force of currents and wave action can directly disturb sediments (Brooks, 1991; CSA, 1992), 

increasing turbidity and associated impacts. Severe weather can also have secondary impacts, 

such as causing movement of abandoned fishing gear and causing accidental losses of equipment 

overboard or even the toppling of entire platforms. In general, live bottom communities have 

adapted over millennia to deal with natural levels of severe weather, but changing climatic conditions 

that alter the frequency and/or severity of severe weather events could impact live bottom resources 

in unforeseen ways to which live bottoms may not be able to adapt.

Climate change-related effects have the potential to alter baseline environmental conditions 

throughout the GOM. An additional review of climate change is presented in the Five-Year Program 

EIS (USDOI, BOEM, 2016b). Of particular note for live bottom communities are the potential 

negative consequences that may be caused by the dual mechanisms of increasing ocean 

temperatures and ocean acidification and associated reductions in the bioavailability of calcium 

carbonate. Sustained, unusually high water temperatures are documented to cause coral bleaching, 

in which symbiotic zooxanthellae are expelled from coral polyps. Ocean acidification can inhibit 

normal rates of calcification by exoskeleton-building corals and other calcifying marine organisms, 

and decreased calcification rates have been observed in numerous shallow-water, zooxanthellate 

corals (refer to Hofmann et al., 2010). Both mechanisms can inhibit growth and reproductive fitness.

The cumulative impact level of each of these individual factors is difficult to accurately 

estimate since the spatial and temporal characteristics of some factors are rapidly changing and 

necessary baseline information is still being collected. However, at present, the overall impact of 

these non-OCS oil- and gas-related factors is estimated to be minor to moderate, with individual 
Description of the Affected Environment and Impact Analysis 4-179

species affected to different degrees by each factor. Over the next 50 years, the impact level from 

these non-OCS oil- and gas-related factors could potentially rise to as great as major for some 

species, should current trends of these factors continue or worsen.

Weighed against these potential non-OCS oil- and gas-related impacts, the cumulative 

impact of a proposed lease sale is expected to contribute only a negligible amount to the more 

serious expected impacts of non-OCS oil- and gas-related activities.

Incomplete or Unavailable Information

BOEM recognizes that there is incomplete or unavailable information related to GOM live 

bottom habitats in general and specifically in relation to routine activities, accidental events, and 

cumulative impacts for OCS oil- and gas-related activities and cumulative non-OCS oil- and gasrelated activities. However, the information that is known is adequate to come to a determination

with respect to reasonably foreseeable impact-producing factors associated with a proposed action.

Research in offshore marine systems is logistically complex and requires substantial 

resources to conduct. The total amount of research on live bottom habitats has therefore been 

limited, although BOEM and its predecessor agencies have funded numerous studies over the past 

40 years. An example of incomplete knowledge about this resource would be that the exact 

distribution of GOM live bottom habitats at any given time is not perfectly understood. This is due in 

part to limits on data collection but also due to the frequent burial and exposure of low-relief hard 

bottoms. To help address this knowledge gap, BOEM requires operators to provide detailed, 

updated, site-specific survey information about potential live bottom habitats; this information is 

reviewed by subject-matter experts prior to approval of individual proposed activities, and 

appropriate protective mitigations are applied where appropriate.

Although BOEM has acquired and applies a good deal of knowledge about possible impacts 

to live bottom habitats, a perfect understanding of all conceivable impacts is unattainable. For 

example, only recently did a study (Silva et al., 2015) provide compelling evidence that mixing of a 

surface oil/dispersant mixture to the depths of the Pinnacle Trend live bottom features can occur 

given an unusual combination of conditions and could then have a localized impact. Given the 

geographic and temporal scope of a proposed action, it is believed that even impacts resulting from 

that particular scenario would still only have a slight impact on the overall status of GOM live bottom 

habitats, and the amount of oil/dispersant mixture in that catastrophic situation greatly exceeded the 

amounts considered in the “Accidental Events” analysis. However, the example demonstrates the 

point that the body of literature supporting impact analysis is still growing and requires continual 

review by BOEM.

Known information about potential impacts of a theoretical catastrophic spill is detailed in the 

Catastrophic Spill Events Analysis white paper (USDOI, BOEM, 2016c). However, a great deal of 

information related to impacts specific to the Deepwater Horizon explosion, oil, spill, and response is 

still incomplete or unavailable. BOEM has determined that such additional information could not be 
4-180 Gulf of Mexico Multisale EIS

timely acquired and incorporated into the current analysis. However, based on the currently 

available evidence, outstanding reports are not expected to reveal additional significant effects that 

would alter the overall conclusions about reasonably foreseeable impact-producing factors 

associated with a proposed action.

BOEM will continue to analyze and support collection and analysis of the best available 

scientific information related to live bottom habitats. BOEM used reasonably accepted scientific 

methodologies to extrapolate from existing information in completing this analysis and formulating 

the conclusions presented here. BOEM has determined that the incomplete information is not 

essential to a reasoned choice among alternatives.

4.6.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

The activities proposed under Alternative A could directly impact live bottom pinnacle and 

low-relief features within the GOM. The primary, reasonably foreseeable, impact-producing factors 

for deepwater benthic habitats can be grouped into three main categories: (1) bottom-disturbing 

activities; (2) sediment and waste discharges; and (3) oil spills. The proposed Live Bottom 

Stipulation, along with site-specific reviews of permit applications and associated distancing 

requirements, would mitigate potential impacts to live bottom communities as a result of both routine 

activities and accidental disturbances. Assuming adherence to all expected lease stipulations and 

other postlease protective restrictions and mitigations, the routine activities are expected to have 

mostly short-term, localized, and temporary effects on live bottom communities that may not be 

clearly detectable. Therefore, at the regional, population-level scope of this analysis, the impacts of 

routine activities would be expected to be negligible. 

Accidental events (below the threshold of a catastrophic spill, which is detailed in the 

Catastrophic Spill Event Analysis white paper [USDOI, BOEM, 2016c]) have the potential to cause 

detectable, severe damage to specific live bottom communities. However, the number of such 

events is expected to be very small and localized, and impacts might not be clearly distinguishable 

from natural variation. Therefore, at the regional, population-level scope of this analysis, impacts 

from reasonably foreseeable accidental events are expected to be negligible to minor. 

Proposed and existing OCS oil- and gas-related activities would also contribute incrementally 

to the overall OCS oil- and gas-related and non-OCS oil- and gas-related cumulative effects 

experienced by live bottom habitats. A variety of non-OCS oil- and gas-related activities, including 

fishing and anchoring, along with shifting natural conditions such as invasive species and climate 

change-related factors, may have a considerable impact on live bottom communities over the next 

50 years. Weighed against these potential non-OCS oil- and gas-related impacts, the cumulative 

impact of a proposed action under Alternative A is expected to contribute only a negligible amount to 

the more serious expected impacts of non-OCS oil- and gas-related activities.
Description of the Affected Environment and Impact Analysis 4-181

4.6.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM would hold a lease sale excluding the available unleased WPA 

blocks and would offer all available unleased blocks in the CPA and a portion of the EPA. 

Alternative B would not fundamentally alter the conclusions reached under Alternative A, but it would 

reduce the potential impacts of a proposed sale in the available unleased WPA blocks. The impacts 

from proposed activities to live bottom communities would remain the same in leased portions of the 

CPA/EPA. Impacts resulting from accidental events should remain relatively localized, with the 

number of features affected being directly proportional to the size of the accident. An accident along

the CPA/WPA border has the possibility to impact features in either planning area. Live bottom 

communities are found throughout the GOM, and therefore, the impacts associated with Alternative 

B could still potentially cause some population-level effects.

At the regional, population-level scope of this analysis, the overall impact to live bottom 

communities as a result of the activities proposed under Alternative B are expected to be the same 

as Alternative A, i.e., negligible to minor, assuming the application of the Live Bottom (Pinnacle 

Trend) Stipulation and continuation of expected mitigation practices. BOEM’s mitigation practices 

would reduce the potential impacts as a result of routine activities and accidental events, and OCS 

oil- and gas-related cumulative impacts of a proposed sale under Alternative B to the range of 

negligible to minor. Absent these mitigations, the impacts resulting from routine activities and 

accidental events of a proposed sale under Alternative B could be greater; the overall populationlevel impact could range from minor to moderate (in a theoretical, if improbable, worst-case 

scenario). This impact level is less than the potential major level impact that would be possible 

(absent mitigations) under Alternative A. This difference is due to the reduced area available for 

new leasing under Alternative B, which would somewhat limit the number of potentially affected live 

bottom communities (including concentrations of known live bottom communities in the South Texas 

Banks) and increase the likelihood of long-term recovery to pre-impact levels. However, it is 

believed that existing mitigation practices would continue to be applied to the proposed activities 

under all action alternatives, reducing the expected level of OCS oil- and gas-related impacts.

The incremental cumulative impacts of proposed and existing OCS oil- and gas-related 

activities under Alternative B are considered to add only a negligible contribution to the overall 

cumulative impact, which includes the relatively greater influence of non-OCS oil-and gas-related 

cumulative impacts occurring throughout the GOM over the 50-year analysis period.

4.6.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Under Alternative C, BOEM would hold a lease sale excluding the CPA/EPA available 

unleased blocks and would offer all available unleased blocks in the WPA. Alternative C would not 

fundamentally alter the conclusions reached under Alternative A, but it would reduce the potential 

impacts of a proposed lease sale of the available unleased CPA/EPA blocks, including known 

concentrations of live bottoms in the Pinnacle Trend blocks and other portions of the northeastern 
4-182 Gulf of Mexico Multisale EIS

CPA (Figure 4-17). The impacts from proposed activities to live bottom communities would remain 

the same in leased portions of the WPA. Impacts resulting from accidental events should remain 

relatively localized, with the number of features affected being directly proportional to the size of the 

accident. An accident along the CPA/WPA border has the possibility to impact features in either 

planning area. Live bottom communities are found throughout the GOM, not just in the CPA/EPA,

and therefore, the impacts associated with Alternative C could still potentially cause some 

population-level effects.

At the regional, population-level scope of this analysis, the overall impact to live bottom 

communities as a result of the activities proposed under Alternative C are expected to be the same 

as Alternative A, i.e., negligible to minor, assuming the application of the Live Bottom (Pinnacle 

Trend) Stipulation and continuation of expected mitigation practices. BOEM’s mitigation practices 

would reduce the potential impacts as a result of routine activities and accidental events, and OCS 

oil- and gas-related cumulative impacts of a proposed lease sale under Alternative C to the range of 

negligible to minor. Absent these mitigations, the impacts resulting from routine activities and 

accidental events of a proposed lease sale under Alternative C could be greater; the overall 

population-level impact could range from negligible to moderate (in a theoretical, if improbable, 

worst-case scenario). This impact level is less than the potential major level impact that would be 

possible (absent mitigations) under Alternative A. This difference is due to the reduced area 

available for new leasing under Alternative C, which would somewhat limit the number of potentially 

affected live bottom communities (including large concentrations of known live bottom communities 

in the live bottom Pinnacle Trend blocks and other portions of the northeastern CPA, i.e., higher 

concentrations than are known to occur in the WPA and thus a different impact range than under 

Alternative B) and increase the likelihood of long term recovery to pre-impact levels. However, it is 

believed that existing mitigation practices would continue to be applied to the proposed activities 

under all action alternatives, reducing the expected level of OCS oil- and gas-related impacts.

The incremental cumulative impacts of proposed and existing OCS oil- and gas-related 

activities under Alternative C are considered to add only a negligible contribution to the overall 

cumulative impact, which includes the relatively greater influence of non-OCS oil-and gas-related 

cumulative impacts occurring throughout the GOM over the 50-year analysis period.

4.6.2.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, BOEM could hold a lease sale excluding leasing on any and/or all 

blocks subject to the Topographic Features, Live Bottom (Pinnacle Trend), and Blocks South of 

Baldwin County, Alabama, Stipulations. Known live bottom features in the Pinnacle Trend area 

would be further protected by the increased distancing of OCS oil- and gas-related activities. An 

accidental spill may still reach some Pinnacle Trend features, but if so, it is expected that such a spill 

would be more dispersed and diluted from having to travel the additional distance across the 

unleased blocks.
Description of the Affected Environment and Impact Analysis 4-183

The impacts from the proposed activities to live bottom communities would remain the same 

in all other leased portions of the OCS. Impacts resulting from accidental events should remain 

relatively localized, with the number of features affected being directly proportional to the size of the 

accident. An accident along the border of available unleased blocks subject to the Topographic 

Features and Live Bottom (Pinnacle Trend) Stipulations still has the possibility to impact features 

within those unleased blocks. Live bottom communities are found throughout the GOM, not just in 

the blocks subject to the Topographic Features and Live Bottom (Pinnacle Trend) Stipulations, and 

therefore, the impacts associated with Alternative D could still potentially cause some populationlevel effects. The exclusion of blocks subject to the Blocks South of Baldwin County, Alabama 

Stipulations is not expected to change the impacts to pinnacles and/or low-relief features because of 

the small number of blocks and their distance from identified features.

At the regional, population-level scope of this analysis, the overall impact to live bottom 

communities as a result of the activities proposed under Alternative D are expected to be the same 

as Alternative A, i.e., negligible to minor, assuming the application of the Live Bottom (Pinnacle 

Trend) Stipulation and continuation of expected mitigation practices. BOEM’s mitigation practices 

would reduce the potential impacts as a result of routine activities and accidental events, and OCS 

oil- and gas-related cumulative impacts of a proposed lease sale under Alternative D to the range of 

negligible to minor. Absent these mitigations, the impacts resulting from routine activities and 

accidental events of proposed lease sale under Alternative D could be greater; the overall 

population-level impact could range from negligible to moderate (in a theoretical, if improbable, 

worst-case scenario). This impact level is less than the potential major level impact that would be 

possible (absent mitigations) under Alternative A. This difference is due to the reduced area 

available for new leasing under Alternative D, which would somewhat limit the number of potentially 

affected live bottom communities (including large concentrations of known live bottom communities 

in the topographic features blocks and live bottom blocks, i.e., higher concentrations than are known 

to occur in the WPA and thus a different impact range than under Alternative B) and increase the 

likelihood of long-term recovery to pre-impact levels. However, it is believed that existing mitigation 

practices would continue to be applied to the proposed activities under all action alternatives, 

reducing the expected level of OCS oil- and gas-related impacts.

The incremental cumulative impacts of proposed and existing OCS oil- and gas-related 

activities under Alternative D are considered to add only a negligible contribution to the overall 

cumulative impact, which includes the relatively greater influence of non-OCS oil-and gas-related 

cumulative impacts occurring throughout the GOM over the 50-year analysis period.

4.6.2.2.5 Alternative E—No Action

Under Alternative E, a proposed lease sale would be cancelled. Therefore, the potential for 

impacts would be none because new impacts to live bottom communities related to the cancelled 

lease sale would be avoided entirely. Continuing impacts to the communities would be limited to 

existing impacts resulting from routine activities and accidental events, and cumulative impacts 

associated with previous OCS lease sales and development. BOEM’s current Live Bottom 
4-184 Gulf of Mexico Multisale EIS

Stipulation and mitigation practices already regulate these activities and should continue to limit 

associated new impacts to the negligible to minor range.

Development of oil and gas would, in all likelihood, be proposed again in a future lease sale; 

in that case, the overall level of OCS oil- and gas-related activity would only be delayed, not 

reduced, at least in the short term.

Ongoing non-OCS oil- and gas-related activities are difficult to accurately estimate since the 

spatial and temporal characteristics of some factors are rapidly changing, and necessary baseline 

information is still being collected; however, at present, these non-OCS oil- and gas-related activities 

are having minor to moderate cumulative impacts on live bottom communities. These could 

potentially become greater for some species, even rising to major over the next 50 years, should 

current trends of these factors continue or worsen.

4.7 FISHES AND INVERTEBRATE RESOURCES

Fish and invertebrate resources of the GOM comprise a large and diverse group of species 

(Felder et al., 2009). The distribution of fishes and invertebrates vary widely and species may be 

associated with different habitats at various life stages. This analysis highlights behaviors and 

habitat preferences, but it does not attempt to provide a comprehensive list of all potentially 

impacted fauna. For purposes of this analysis, habitat preferences can be divided into three broad 

categories: estuarine; coastal; and oceanic. Exposure to specific impact-producing factors 

generated by OCS oil- and gas-related routine activities and accidental events can vary among 

these categories. Coastal and oceanic resources are further broken into benthic and pelagic zones 

to address differences in potential exposure to impact-producing factors within a given habitat 

category. Ichthyoplankton bridges all three categories. Egg and larval stages of most fishes and 

invertebrates can be found in the upper layer of the water column, exposing these species’ early life 

stages to similar impact-producing factors. For these reasons, the description of the affected 

environment for fish and invertebrate resources is broken into estuarine, coastal, and oceanic 

habitats, and the surface waters occupied by ichthyoplankton are described separately. A brief 

discussion of the federally managed species is provided at the end of the “Description of the 

Affected Environment” below (Chapter 4.7.1).

A full analysis of the “Environmental Consequences” is presented in Chapter 4.7.2.1. 

Analyses of the specific alternatives do not restate the full analysis of the impact-producing factors 

potentially affecting fishes and invertebrate resources; the analyses identify the potential impacts as 

a result of routine activities, accidental events, and cumulative impacts. This avoids excessive 

replication of the discussion of similar if not identical impacts for each alternative.

Preliminary analysis of routine OCS oil- and gas-related activities and reasonably 

foreseeable accidental events identified nine impact-producing factors with the potential to affect 

marine fishes and invertebrates and/or their habitat. Many OCS oil- and gas-related activities affect 

the environment similarly. For example, vessel traffic, exploratory drilling, geophysical activities, and 
Description of the Affected Environment and Impact Analysis 4-185

offshore construction all produce sound. The impact-producing factor, “anthropogenic sound,” was 

analyzed taking all sound-producing OCS activities into consideration. The following are impactproducing factors that were considered and analyzed in this resource analysis:

• anthropogenic sound (Chapter 3.3.2.7);

• bottom-disturbing activity (Chapter 3.1.3.3.1);

• habitat modification; and

• oil spills (Chapter 3.2.1).

Two impact-producing factors that were considered for fishes and invertebrate resources but 

determined to be insignificant under all reasonably foreseeable circumstances due to the limited 

exposure and/or response expected for fish and invertebrate resources are not included in this 

chapter. These impact-producing factors are entrainment (Chapter 3.1.5.1.6) and offshore lighting 

(Chapter 3.1.3.4.4). Analyses of two additional impact-producing factors that could potentially 

impact resources ecologically important to fishes and invertebrates were found to sufficiently 

address the potential for adverse impacts to the respective habitats and are not duplicated in this 

chapter. These impact-producing factors are onshore construction and manufacturing (Chapters 

3.7 and 4.3, Coastal Habitats) and regulated discharges (Chapters 3.1.5 and 4.2, Water Quality).

Analysis of potential impacts considered the estimated scale of source activities and used 

the best available science to evaluate how specific impact-producing factors could affect resources 

within the expected environment. Cumulative impacts (Chapter 4.7.3) were analyzed for OCS oiland gas-related activities and for other sources that could affect fishes and invertebrates (e.g., 

coastal development, commercial shipping, fisheries, and environmental). Because of the diversity 

of fishes and invertebrates, detailed criteria for potential impact levels are not reasonable.

Impact-Level Definitions

For this analysis, the potential impact-level criteria can be described in terms of populationlevel effects.

• Negligible – localized and temporary impacts that are expected to be 

indistinguishable from natural variations in population distribution and 

abundance.

• Minor – localized and temporary impacts that are expected to be 

indistinguishable from natural variations in population distribution and 

abundance. Community-level variations may be locally detectable, such as 

species mix and relative abundance following the removal of OCS oil- and gasrelated infrastructure.

• Moderate – Impacts would be expected to exceed natural variations in 

population abundance or distribution, but not result in a long-term decline.
4-186 Gulf of Mexico Multisale EIS

• Major – Impacts would be expected to exceed natural variations and inherently 

result in a long-term decline in populations.

Though two protected fish species (Gulf sturgeon [Acipenser oxyrhynchus desotoi] and 

smalltooth sawfish [Pristis pectinata]) are found near the area of interest, they inhabit and have 

critical habitat in onshore waters. These species are not considered to be impacted by a proposed 

action because they are found away from activities that could cause an impact. The impactproducing factors analyzed and the impact-level conclusions reached from the analysis in this 

chapter are presented in Table 4-10. 

Table 4-10. Fish and Invertebrate Resources Impact-Producing Factors.

Fish and 

Invertebrate 

Resources

Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Anthropogenic 

Sound Minor Minor Minor Minor None

Bottom-Disturbing 

Activity Negligible Negligible Negligible Negligible None

Habitat 

Modification

Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Accidental Impacts

Oil Spills Negligible Negligible Negligible Negligible None

Cumulative Impacts

OCS Oil and Gas

Anthropogenic 

Sound Minor Minor Minor Minor Minor

Bottom-Disturbing 

Activity Negligible Negligible Negligible Negligible Negligible

Habitat 

Modification

Negligible to Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate Moderate

Non-OCS Oil and Gas

Anthropogenic 

Sound Moderate Moderate Moderate Moderate Moderate

Fisheries Negligible to Negligible to Negligible to Negligible to Negligible to

Moderate Moderate Moderate Moderate Moderate

Habitat 

Modification Minor Minor Minor Minor Minor

4.7.1 Description of the Affected Environment

The ecological factors influencing the distribution of fish and invertebrate species include 

salinity, temperature, depth, primary productivity, and bottom type. These factors vary widely across 
Description of the Affected Environment and Impact Analysis 4-187

the Gulf of Mexico and between inshore and offshore waters. Fish and invertebrate resources are 

associated with the various environments and are not randomly distributed. High densities of fish 

and invertebrate resources can be associated with particular habitat types; for detailed habitat 

information, distribution, potential impacts, and mitigations, refer to Chapters 4.3 (Coastal Habitats), 

4.5 (Deepwater Benthic Communities), 4.5 (Sargassum and Associated Communities), and 4.6 (Live 

Bottom Habitats), and to the Essential Fish Habitat Assessment white paper (USDOI, BOEM, 

2016d). Because wide variations in habitat usage can occur throughout a species’ life history, 

potential impacts have been analyzed in three broad habitat categories (i.e., estuarine, coastal, and 

oceanic) and one life history category (i.e., ichthyoplankton). These categories are not divided by 

fixed boundaries but by generalized conditions and characteristics typical of the habitat where a fish 

or invertebrate may spend the bulk of its life.

Estuarine

Estuaries are typically semi-enclosed areas where marine saltwater is diluted by freshwater 

and where salinity may vary widely from day to day. The freshwater input (e.g., bayou, stream, or 

river) delivers sediment and nutrients that result in turbid, productive environments. Estuaries 

include many important habitat types (e.g., wetlands, seagrasses, and mudflats) and are frequently 

areas with high biomass. However, these environments can also have high energetic costs for 

resident organisms due to the fluctuating conditions. Many of the fishes and invertebrates found in 

mid- or near-shelf waters are dependent on or opportunistically make use of estuaries at some point 

in their life cycle. For example, estuaries provide nursery habitat for Gulf menhaden (Brevoortia 

patronus), spotted sea trout (Cynoscion nebulosus), blue crab (Callinectes sapidus), brown shrimp 

(Farfantepenaeus aztecus), and gag (Mycteroperca microlepis). The eastern oyster (Crassostrea 

viginica) is an example of a species that both benefits from the environmental conditions in estuarine 

habitat and serves as an important substrate. Bull sharks (Carcharhinus leucas) opportunistically 

make use of estuarine habitat and are common in estuaries and coastal waters. Estuaries may be 

subject to extreme tidal exchange, strong currents, water-column stratification, and/or rapid 

fluctuations in dissolved oxygen.

Coastal

Coastal waters are defined here as those waters extending from the shoreline seaward over 

the continental shelf. These waters are enriched by organic material exported from the estuaries 

and rivers of the GOM and support the greatest biomass of the three categories. Many species in 

the coastal waters of the GOM exploit the entire water column; the following subcategories are used 

to distinguish between zones in which species are predominantly found.

Coastal Pelagics

Pelagic fishes are primarily found in waters associated with neither the shore nor the 

seafloor. Commercial fishery landings are one of the best sources of information for coastal pelagic 

fishes because these species are an important component of regional fisheries. Coastal pelagic 
4-188 Gulf of Mexico Multisale EIS

species traverse shelf waters of the region throughout the year. Major coastal pelagic families 

occurring in the region include

• Carcarhinidae (requiem sharks), 

• Elopidae (ladyfish), 

• Engraulidae (anchovies), 

• Clupeidae (herrings), 

• Scombridae (mackerels and tunas), 

• Carangidae (jacks and scads), 

• Mugilidae (mullets), 

• Pomatomidae (bluefish), and 

• Rachycentridae (cobia).

The distribution of most species depends upon water-column characteristics that vary 

spatiotemporally. Coastal pelagic species with an affinity for vertical structure are often observed 

around topographic features and offshore platforms, where they are best classified as transients 

rather than resident fishes. Spawning typically occurs over the mid- or inner-continental shelf, eggs 

and larvae are pelagic, and juveniles are common in estuaries and coastal waters. Coastal pelagic 

fishes can be divided into two general groups: large predatory species (e.g., Spanish mackerel, 

cobia, and coastal sharks); and smaller, omnivorous and herbivorous species, such as Gulf 

menhaden (Brevoortia patronus) and striped mullet (Mugil cephalus). Members of both groups may 

form large schools. The predatory species typically undergo migrations, grow rapidly, mature early, 

and exhibit the ability to produce a large number of eggs, while the latter group includes many 

estuarine-dependent species that are frequently preyed upon by members of the first group. These 

fishes are ecologically important to energy transfer in the nearshore environment and, in many 

cases, are subject to significant fishing pressure. Large schools of squid (e.g., Doryteuthis pealeii 

and Lolliguncula brevis) can also be found over the continental shelf, and many less well-known 

cephalopods inhabit the GOM, ranging from nearshore waters to oceanic waters (Voss and 

Brakoneicki, 1985; Felder et al., 2009).

Coastal Demersal

Most of the benthic habitat in the northern GOM can be described as low-relief soft bottom 

habitat (i.e., mud, clay, and sand). Demersal fish and benthic invertebrates live and forage at the 

seafloor. White shrimp (Litopenaeus setiferus), hardhead catfish (Arius felis), Atlantic croaker 

(Micropogonias undulatus), and cownose rays (Rhinoptera bonasus) are common to inshore soft 

bottom habitat. Over the inner- and mid-shelf, and in association with deeper topographic features, 

red snapper (Lutjanus campechanus) provide an example of an opportunistic fish. This species 

feeds on the bottom and throughout the water column. Older and larger fish inhabit open bottom 
Description of the Affected Environment and Impact Analysis 4-189

and habitat with vertical structure, whereas young adults tend to recruit to habitat with vertical 

structure (Gallaway et al., 2009). Scattered low-relief hard bottom features and several significant 

higher relief features are located on the shelf. Thirteen banks have been identified by the Gulf of 

Mexico Fisheries Management Council (GMFMC) as being important features in the northwestern 

GOM, and these banks are designated as habitat areas of particular concern (HAPCs). Where hard 

bottom occurs, demersal species and opportunistic reef fish species more commonly associated with 

the mid- or inner-shelf may also be found. Species particularly adapted for deeper hard bottom 

areas include snowy grouper (Epinephelus niveatus), yellowedge grouper (Epinephelus 

flavolimbatus), and gag (Mycteroperca microlepis). Outer shelf demersal assemblages 

(approximately 656- to 984-ft [200- to 300-m] water depth) might include three-eye flounder 

(Ancylopsetta dilecta), deepbody boarfish (Antigonia capros), and armored searobins (Peristedion 

miniatum).

Oceanic

For purposes of this impact analysis, oceanic waters are generally defined as those waters 

seaward of the continental shelf, although oceanographic features and storms can cause these 

waters to intrude over the mid- or inner-shelf. Information on the distribution and abundance of 

oceanic species comes from commercial longline catches, recreational fishing surveys, and 

relatively few independent research efforts. Pelagic fishes occur throughout the water column in the 

open ocean. Within this vast habitat, water-column structure (i.e., temperature, salinity, and 

turbidity) is the primary means of partitioning for analyses. In general, pelagic fishes recognize 

different watermasses based upon physical and biological characteristics. The following 

subcategories are used to distinguish among assemblages based on predominant depth inhabited: 

epipelagic – extends from the surface to a depth of 656 ft (200 m); mesopelagic – extends from 656 

to 3,281 ft (200 to 1,000 m); and bathypelagic – includes depths greater than 3,281 ft (1,000 m). 

The demersal category is also included and encompasses those species associated with the deep 

seafloor.

Epipelagic

Oceanic epipelagic species occur throughout the GOM, especially at or beyond the shelf 

edge. Epipelagics are reportedly associated with mesoscale hydrographic features such as fronts, 

eddies, and discontinuities. Many of the oceanic fishes also associate with drifting Sargassum, 

which provides forage areas and/or nursery refugia (Chapter 4.5, Sargassum and Associated 

Communities). Common fishes in this zone include halfbeaks and flying fishes (Exocoetidae), and 

early life stage driftfishes (Ariommatidae). Several well-known large predators are also epipelagic 

species, including bluefin tuna (Thunnus thynnus), swordfish (Xiphias gladius), dolphinfish 

(Coryphaena hippurus), wahoo (Acanthocybium solanderi), and shortfin mako (Isurus oxyrinchus). 

The lower section of this epipelagic zone has a distinct fauna, consisting of the poorly known 

oarfishes and its relatives, in addition to fishes with great depth ranges such as tunas (Scombridae) 

and swordfishes (Xiphiidae) (McEachran and Fechhelm, 1998). Adult driftfishes are generally found 

at depths bridging the lower epipelagic and upper mesopelagic zones.
4-190 Gulf of Mexico Multisale EIS

Mesopelagics

The mesopelagic realm is below the photic zone and below the permanent thermocline. 

Mesopelagic fish assemblages in the GOM are numerically dominated by myctophids 

(lanternfishes), with gonostomatids (bristlemouths) and sternoptychids (hachetfishes) common but 

less abundant in collections. These fishes make extensive vertical migrations during the night from 

mesopelagic depths (200-1,000 m; 656-3,281 ft) to feed in higher, food rich layers of the water 

column (McEachran and Fechhelm, 1998). Mesopelagic fishes are ecologically important because 

they transfer substantial amounts of energy between mesopelagic and epipelagic zones over each 

diel cycle.

Bathypelagics

The deeper dwelling bathypelagic fishes inhabit the water column at depths >1,000 m 

(3,281 ft) and seldom migrate into shallower waters. This zone receives no sunlight and 

temperatures range from 4 °C to 10 °C (39 °F to 50 °F). Numerous species of gonostomatids 

(bristlemouths or lightfishes) and scaleless black dragonfishes (Melanostomiidae) are found in the 

bathypelagic of the GOM. Like mesopelagic fishes, most species are capable of producing and 

emitting light (bioluminescence) to aid in communication in an environment devoid of sunlight 

(Snyder, 2000).

Demersal

Three major deep-sea studies have collected demersal fish throughout the depth range of 

the GOM’s continental slope between the 1960’s and as recently as 2003. The families Macrouridae 

(grenadiers or rattails), Ophidiidae (cuskeels), and Alepocephalidae (slickheads) dominated the 

samples (Rowe and Kennicutt, 2009). Analysis of the data suggested an upper slope assemblage 

between 1,033 and 2,575 ft (315 and 785 m), a mid-slope assemblage between 2,251 and 4,491 ft 

(686 and 1,369 m), and a deep assemblage between 5,030 and 10,089 ft (1,533 and 3,075 m) 

(Rowe and Kennicutt, 2009). Shelf edge and upper slope species include tilefish (Lopholatilus 

chamaeleonticeps) and snowy grouper (Epinephelus niveatus).

Ichthyoplankton

Most fishes inhabiting the GOM, whether benthic or pelagic as adults, have pelagic larval 

stages. For the duration of this stage, these eggs and larvae become part of the planktonic 

community. Variability in survival and transport of pelagic larval stages is thought to be an important 

determinant of future year-class strength in adult populations of fishes and invertebrates 

(Underwood and Fairweather, 1989; Doherty and Fowler, 1994). In general, the distribution of fish 

larvae depends on the spawning behavior of adults, hydrographic structure and transport at a variety 

of scales, duration of the pelagic period, behavior of larvae, larval mortality, and growth (Leis, 1991). 

Larval fishes are highly dependent on zooplankton until they can feed on larger prey.

Two important hydrographic features in the GOM are the Mississippi River discharge plume 

and the Loop Current. Combined with wind regimes in the region, these features strongly influence 
Description of the Affected Environment and Impact Analysis 4-191

the transport and distribution of pelagic eggs and larvae. Water from the Mississippi River exits from 

several passes, delivering approximately one-third its volume to the Mississippi-Alabama shelf and 

two-thirds to the Texas-Louisiana shelf. The convergence and mixing of this many plumes is 

associated with continually reforming turbidity fronts and an accumulation of larvae at the plume 

boundary (Wiseman and Sturges, 1999). Planktonic eggs and larvae also become concentrated at 

the frontal boundaries of the Loop Current, shed rings, and gyres. Entrained Sargassum provides 

nursery habitat and refuge for many of these early life stage fish, and upwelling at the edges of the 

Loop Current and rings delivers nutrient-enriched waters to the surface, increasing primary 

production. Frontal waters of both the river plume and eddy boundaries provide feeding and growth 

opportunities for larvae.

Managed Species

For purposes of this analysis, managed species are those identified in a fishery management 

plan by a regional fishery management council or as a federally managed species. These species 

are subject to monitoring and management regulations. Fish species currently managed in the GOM 

are listed in Table D-1 of the Essential Fish Habitat Assessment white paper (USDOI, BOEM, 

2016d). Detailed descriptions of species abundance, life histories, and habitat associations for all 

life history stages are presented in the “Generic Amendment for Essential Fish Habitat” by the 

GMFMC (1998) and updated in the “Essential Fish Habitat Generic Amendment 3” (GMFMC, 2005). 

Information on federally managed species and EFH is provided in the Consolidated Atlantic Highly 

Migratory Species Fishery Management Plan and amendments. These fishes and invertebrates are 

included in the preceding categories and are considered in the respective analyses for impacts 

below. Increased susceptibility to potential impacts as a result of fishing pressures will be discussed 

in the “Cumulative Impacts” section below.

4.7.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts described in Chapter 3 and their 

potential effects on fish and invertebrate resources that would potentially result from a proposed 

action or the alternatives. This analysis applies to all considered alternatives. While the WPA is a 

smaller area with less projected activity than is proposed for the CPA/EPA (refer to Chapter 3), the 

distribution of fishes and invertebrate species is nonrandom and generally even throughout their 

range of habitat within the planning areas. As such, the potential for impacts to populations is 

independent of the planning area(s) analyzed. Differences in the specific populations potentially 

exposed to impact-producing factors and the potential impacts may be more easily estimated as 

specific sites and activities become known. Therefore, because of the diversity and distribution of 

species in the Area of Interest, the level of impacts would be the same for Alternatives A, B, C, 

and D. However, Alternative E would have no impacts as a proposed action would not be 

implemented; therefore, the only impacts would be those associated with the continuing effects from 

past lease sales and non-OCS oil- and gas-related activities. Following this environmental 

consequences chapter, there will be a summary of the potential impacts as they relate to the action 

alternatives.
4-192 Gulf of Mexico Multisale EIS

Routine Activities

Routine OCS oil- and gas-related activities that take place on the OCS as a result of a 

proposed action and that produce sound, disturb the seafloor, or otherwise modify the habitat, could 

impact fish and invertebrate resources. A full list of impact-producing factors and scenarios for 

routine activities can be found in Chapter 3.1. 

Anthropogenic Sound

Natural background noise in a marine environment is the result of physical processes (i.e., 

wind, wave action, tidal movement, and geological activity) and bioacoustic signals (Wysocki and 

Ladich, 2005; Hildebrand, 2009; Radford et al., 2010; Ladich, 2013). Acoustic signaling in the 

marine environment is extremely efficient, so marine species have evolved several mechanisms for 

producing and receiving sound. Important sound-mediated behaviors can include spawning 

aggregations, larval settlement, territorial disputes, and predator-prey detection (Radford et al., 2010 

and 2014; Slabbekoorn et al., 2010). Despite the growing body of information on fishes, there is 

comparatively little information available on sound detection and sound-mediated behaviors for 

marine invertebrates (Mooney et al., 2012; Normandeau Associates, 2012; de Soto et al., 2013; 

Popper et al., 2014; Samson et al., 2014). The diversity of marine fishes and invertebrates suggests 

the small number of studied species may not be representative of the full range of auditory sensory 

mechanisms and hearing capabilities. Therefore, caution was used in extrapolating potential 

impacts to fishes and invertebrate resources from documented behavioral responses and 

physiological impacts resulting from exposure to anthropogenic sound sources. For purposes of this 

analysis, it was deemed reasonable to use observed results as an indication of the types of impacts 

that may occur as a result of expected discreet and cumulative exposures to anthropogenic sound 

produced by routine OCS oil- and gas-related activities.

All routine OCS oil- and gas-related activities have some element of sound generation. 

Common sound sources include propeller cavitation, rotating machinery, and reciprocating 

machinery, which are associated with routine OCS oil- and gas-related activities such as vessel 

traffic, drilling, construction, and oil and gas production, processing, and transport. Sound 

introduced into the marine environment as a result of human activities has the potential to affect 

marine organisms by stimulating behavioral response, masking biologically important signals, 

causing temporary or permanent hearing loss (Popper et al., 2005; Popper et al., 2014), or causing 

physiological injury (e.g., barotrauma) resulting in mortality (Popper and Hastings, 2009). The 

potential for anthropogenic sound to affect any individual organism is dependent on the proximity to 

the source, signal characteristics, received peak pressures relative to the static pressure, cumulative 

sound exposure, species, motivation, and the receiver’s prior experience. In addition, environmental 

conditions (e.g., temperature, water depth, and substrate) affect sound speed, propagation paths, 

and attenuation, resulting in temporal and spatial variations in the received signal for organisms 

throughout the ensonified area (Hildebrand, 2009).

Sound detection capabilities among fishes vary. All fishes are able to detect low-frequency 

particle motion at short ranges by means of the otolith and lateral line organs (Popper et al., 2003). 
Description of the Affected Environment and Impact Analysis 4-193

Detection of the particle velocity and the ability to determine the position of the source is only 

possible over distances of 1-2 body lengths, but it is important for orientation in flowing water and 

maneuvering in close proximity to other organisms (Popper et al., 2014). Species with a swim 

bladder or accessory structure close to or in contact with the inner ear have increased hearing 

sensitivity and a wider range of detectable frequencies than do fishes with a swim bladder only or 

fishes with no gas-filled structure (Popper et al., 2003). For most fish species, it is reasonable to 

assume hearing sensitivity to frequencies below 500 Hertz (Hz) (Popper et al., 2003 and 2014; 

Popper and Hastings, 2009; Slabbekoorn et al., 2010; Radford et al., 2014). Ambient noise may be 

divided into three general frequency bands (i.e., low, medium, and high), each dominated by 

different sound sources (Hildebrand, 2009). The band of greatest interest to this analysis, lowfrequency sound (30-500 Hz), has come to be dominated by anthropogenic sources and includes 

the frequencies most likely to be detected by most fish species. For example, the noise generated 

by large vessel traffic typically results from propeller cavitation and falls within 40-150 Hz 

(Hildebrand, 2009; McKenna et al., 2012). This range is similar to that of fish vocalizations and 

hearing, and could result in a masking effect.

Masking occurs when background noise increases the threshold for a sound to be detected; 

masking can be partial or complete. If detection thresholds are raised for biologically relevant 

signals, there is a potential for increased predation, reduced foraging success, reduced reproductive 

success, or other effects. However, fish hearing and sound production may be adapted to a noisy 

environment (Wysocki and Ladich, 2005). There is evidence that fishes are able to efficiently 

discriminate between signals, extracting important sounds from background noise (Popper et al., 

2003; Wysocki and Ladich, 2005). Sophisticated sound processing capabilities and filtering by the 

sound sensing organs essentially narrows the band of masking frequencies, potentially decreasing 

masking effects. In addition, the low-frequency sounds of interest propagate over very long 

distances in deep water, but these frequencies are quickly lost in water depths between 1⁄2 and 1⁄4 the 

wavelength (Ladich, 2013). This would suggest that the potential for a masking effect from lowfrequency noise on behaviors occurring in shallow coastal waters may be reduced by the receiver’s 

distance from sound sources, such as busy ports or construction activities.

Pulsed sounds generated by OCS oil- and gas-related activities (e.g., impact-driven piles 

and airguns) can potentially cause behavioral response, reduce hearing sensitivity, or result in 

physiological injury to fishes and invertebrate resources. Impact pile-driving during OCS 

construction and on-lease seismic activity are both temporally and spatially limited activities. The 

effects of these sound-producing activities would extend only to communities of fishes and 

invertebrates within a relatively small area. Benthic fishes and invertebrates could receive sound 

waves propagated through the water and sound waves propagated through the substrate. However, 

Wardle et al. (2001) found that, although fishes and invertebrates associated with a reef exhibited a 

brief startle response when exposed to pulsed low-frequency signals, disruption of diurnal patterns 

was not observed. Fishes disturbed by the noise were observed to resume their previous activity 

within 1-2 seconds and only exhibited flight response if the airguns were visible when discharged 

(Wardle et al., 2001). Other studies of fishes exposed to pulsed anthropogenic sound signals in 

natural environments have produced a wide range of results suggesting that species, experience, 
4-194 Gulf of Mexico Multisale EIS

and motivation are very important factors, and indicating that habituation may occur (Engås et al., 

1996; Løkkeborg et al., 2012; Popper et al., 2014). Organisms in close proximity to a pulsed sound 

source are at increased risk of barotrauma. A signal with a very rapid rise and peak pressures that 

vary substantially from the static pressure at the receiver’s location can cause physiological injury or 

mortality (Popper et al., 2014). However, the range at which physiological injury may occur is short 

(<10 m; <33 ft) and, given fish avoidance behavior, the potential for widespread impacts to 

populations as a result of physiological injury is negligible. 

Despite the importance of many sound-mediated behaviors and the potential biological costs 

associated with behavioral response to anthropogenic sounds, many environmental and biological 

factors limit potential exposure and the effects that OCS oil- and gas-related sounds have on fishes 

and invertebrate resources. The overall impact to fishes and invertebrate resources due to 

anthropogenic sound introduced into the marine environment by OCS oil- and gas-related routine 

activities is expected to be minor. 

Bottom-Disturbing Activities

For the purpose of this analysis, bottom-disturbing activities are distinguished from habitat 

modification by the relatively short period of time over which disturbances occur. Anchoring, drilling, 

trenching, pipe-laying, and structure emplacement are examples of OCS oil- and gas-related 

activities that disturb the seafloor. The specific activity, ocean currents, and water depth can affect 

the extent of the water column and seafloor disturbance, and the magnitude of the effect. For 

example, drilling an exploratory well produces approximately 2,000 metric tons (2,205 tons) of 

combined drilling fluid and cuttings, though the total mass may vary widely for different wells (Neff, 

2005). Cuttings discharged at the surface tend to disperse in the water column and are distributed 

at low concentrations (CSA, 2004b). In deep water, cuttings discharged at the sea surface may 

spread 3,280 ft (1,000 m) from the source, with the majority of the sediment deposited within 820 ft 

(250 m) of the well (CSA, 2006). Drilling mud plumes may be visible 0.6 mi (1 km) from the 

discharge point, but the plumes rapidly become diluted (Shinn et al., 1980; Hudson et al., 1982; Neff, 

2005). Cuttings shunted to the seafloor form piles concentrated within a smaller area than that 

affected by sediments discharged at the sea surface (Neff, 2005). Emplacement of infrastructure 

(i.e., pipelines, platforms, and subsea systems) can also displace large volumes of sediment, 

resulting in increased turbidity and sedimentation (Chapter 3.1.3.3).

Turbidity and sedimentation resulting from routine OCS oil- and gas-related activities are 

short term and have localized effects (Chapter 3.1.3.3.2). The potential impacts to fishes and 

invertebrates (e.g., reduced feeding efficiency, decreased predator avoidance, and behavioral 

responses) may be related to species-specific behaviors and habitat preference (Minello et al., 1987; 

Benfield and Minello, 1996; Chesney et al., 2000; de Robertis et al., 2003; Jönsson et al., 2013; Lunt 

and Smee, 2014). Mobile fishes and invertebrates are expected to avoid the heaviest sedimentation 

and highest suspended sediment loads within 33 ft (10 m) of a disturbance. Icthyoplankton cannot 

avoid sediment plumes at or near the surface and may be exposed for longer durations than adults. 

However, evidence suggesting increased turbidity, which may reduce hatching success or delay 
Description of the Affected Environment and Impact Analysis 4-195

larval development, is limited, and other studies have shown larval foraging success and growth may 

benefit from nutrient-rich plumes (Wenger et al., 2014; Gray et al., 2012). Coastal fishes and 

invertebrate species adapted to turbid environments, such as shallow bays, estuaries, and coastal 

habitat influenced by the Mississippi River plume, may be less affected by increased turbidity than 

species typically inhabiting less turbid environments.

Due to a combination of the spatiotemporally limited nature of suspended sediment plumes 

resulting from bottom-disturbing activities, avoidance behaviors, and a range of tolerances for 

various environmental conditions, the overall impact to fishes and invertebrate resources as a result 

of bottom disturbances associated with OCS oil- and gas-related routine activities is expected to be 

negligible. 

Habitat Modification

For purposes of this analysis, the installation of platforms, pipelines, and subsea systems, or 

the construction of other facilities within a marine environment constitutes habitat modification. 

Although these structures are temporary (refer to Chapter 3.1.6, Decommissioning and Removal 

Operations; Chapter 3.1.6.2, Rigs-to-Reefs Policy; and Chapter 3.3.2.1.2, Artificial Reefs, for more 

information), the operational life is long term and may impact the distribution of species in an area 

(Carr and Hixon, 1997; Gallaway et al., 2009; Shipp and Bortone, 2009). It is generally assumed 

that artificial structures serve 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 

resulting assemblages frequently include commercially and recreationally valuable coastal and 

oceanic fishes. The well-known association with OCS oil- and gas-related structures attracts 

fishermen targeting these species and may subject some fishes to locally increased fishing pressure 

(Dance et al., 2011; Addis et al., 2013). However, infrastructure or pipeline removal also impacts 

fishes and invertebrates associated with the substrate. Removal of the structure is necessary to 

restore the seafloor to the original soft bottom habitat, but it would likely result in an altered 

community as the restored site is recolonized. The removal of hard substrate may result in 

community-level changes, such as an overall reduction in species diversity of epifaunal organisms, 

fishes, and invertebrates (Schroeder and Love, 2004).

Fish mortality can occur as a result of decommissioning operations using explosive 

severance methods; however, a study of the associated mortality for three commercially important 

fishes indicated that the level of explosive severance activity in the GOM did not significantly alter 

stock assessments (Gitschlag et al., 2001). To account for inherent variations in species 

composition and abundance among platforms (e.g., Stanley and Wilson, 1997; Gitschlag et al., 

2001; 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 represented fish populations would 

respond similarly. Impacts to sessile benthic organisms (e.g., barnacles and bivalves) and many 

mobile invertebrates (e.g., shrimp and crabs) that do not possess swim bladders are expected to be 

minimal (Keevin and Hempen, 1997; Schroeder and Love, 2004). Larvae and small juvenile fishes 
4-196 Gulf of Mexico Multisale EIS

have been found to be more susceptible to injury from shock waves than large juveniles or adults 

(Govoni et al., 2008). At the projected rate of removal, these activities are not expected to have a 

substantial negative impact on stocks of managed fishes or other fishes and invertebrates 

associated with OCS oil- and gas-related infrastructure.

Some structures may be converted to artificial reefs. If portions of a platform were permitted 

to be reefed in place, the hard substrate and encrusting communities would remain part of the 

benthic habitat. The diversity of the community would change due to the reduced presence in the 

water column, but some associated fish species would be expected to continue use of the structure. 

Structures removed and redeployed as artificial reef substrate at another location may support 

substantially different communities, depending on the environmental characteristics of the reef site 

and other factors. The plugging of wells and other decommissioning activities that disturb the 

seafloor would impact benthic communities as discussed above.

Some ichthyoplankton studies have been conducted, focusing specifically on the influence of 

offshore platforms. The first of these projects investigated the potential role of platforms as nursery 

habitat for larvae or refugia for postlarval and juvenile fish (Hernandez et al., 2001). A follow-up 

study by Shaw et al. (2002) used data collected at several platforms both east and west of the 

Mississippi River Delta to examine the significance of platforms to larval and juvenile fishes. Both 

Hernandez et al. (2001) and Shaw et al. (2002) found highest taxonomic richness and diversity at 

mid-shelf platforms. Results indicated the distribution of larval and juvenile life stages is influenced 

by across-shelf gradients of increasing depth, similar to the distribution of adult fishes. Differences 

observed in the abundance of certain taxa in larval and juvenile fish assemblages across longitudinal 

gradients may reflect differences in the hydrographic conditions and/or habitat availability (Shaw et 

al., 2002). These results indicate the predominant factors influencing the distribution of larvae and 

juvenile life stages are environmental conditions and the distribution of adult conspecifics. 

Therefore, emplacement and/or removal of OCS oil- and gas-related infrastructure as the result of a 

proposed action is expected to have a negligible impact on the distribution or abundance of 

ichthyoplankton.

Although fish and invertebrate resources may be affected by habitat modifications due to 

routine OCS oil- and gas-related activities, there is no evidence suggesting that population-level 

impacts would occur as a result of a proposed activity. Due to the localized nature of the effects and 

limited number of structure installations and removals anticipated, impacts to fishes and invertebrate 

resources as a result of routine OCS oil- and gas-related activities are expected to range from 

negligible for most species to minor for species most commonly associated with OCS oil- and gasrelated platforms (e.g., sharpnose puffer [Canthigaster rostrate], gray triggerfish [Balistes capriscus], 

great barracuda [Sphyraena barracuda], and red snapper [Lutjanus campechanus]).

Accidental Events

Accidental events resulting in a release of oil or other contaminants (“spills”) could adversely 

affect fish and invertebrate resources. Although an unlikely occurrence, a subsea loss of well control 
Description of the Affected Environment and Impact Analysis 4-197

would also suspend large amounts of sediment. For the reasons stated above (“Bottom-Disturbing 

Activities”), the potential effects of suspended sediments would be negligible. This section will 

address the potential effects to fishes and invertebrate resources resulting from direct and indirect 

exposure to spilled oil. Oil spills, historic trends, the characteristics of oil, and factors affecting the 

fate of oil released into the marine environment are discussed in Chapter 3.2.1, and the potential 

effects on water quality are analyzed in Chapter 4.2 (Water Quality).

The effects of spills in open waters of the OCS proximate to mobile adult fishes would likely 

be sublethal; potential effects would be reduced because adult fish have the ability to avoid adverse 

conditions, metabolize hydrocarbons, and excrete metabolites and parent compounds. However, 

dispersal and emulsification of spilled oil can increase bioavailability to fishes and invertebrates 

throughout the water column. Some filter feeders, such as Gulf menhaden, may have an increased 

risk of exposure due to the likelihood of ingesting high levels of dispersed oil. Increased 

contaminant exposure could result in a higher incidence of chronic sublethal impacts (Millemann 

et al., 2015). Similarly, adsorption of oil to suspended particulate matter and subsequent 

sedimentation increases the potential for chronic exposure of demersal fishes and benthic 

invertebrates to oil (Murawski et al., 2014; Baguley et al., 2015; Snyder et al., 2015). Long-term 

impacts to fish and invertebrate populations in the GOM have not been identified, but studies 

suggest short-term impacts, including increased metabolic costs, immunosuppression, and 

histological lesions (Carls et al., 1998; Brewton et al., 2013). As a result of these effects, fitness and 

productivity of affected individuals may be decreased.

Oil floating on the surface could directly contact ichthyoplankton found at or near the surface, 

coating eggs and larvae. Most ichthyoplankton would be unable to avoid spills and the affected 

individuals may be at risk of death, delayed development, abnormalities, endocrine disruption, or 

other effects, resulting in decreased fitness and reduced survival rates (Incardona et al., 2014; 

Mager et al., 2014; Brown-Peterson et al., 2015; Snyder et al., 2015). In general, early life stages 

are more sensitive to acute oil exposure than adults, but some research indicates that embryos, 

depending on the developmental stage, may be less sensitive to acute exposure than larval stages 

(Fucik et al., 1995). Spills reaching estuarine habitat or overlapping spatiotemporally with a 

spawning event have the greatest potential for affecting the early life stages of fishes and 

invertebrates.

Effects from an accidental event would be expected to be localized; accidental spills have 

historically been small and are low-probability events (Tables 3-12 and 3-17). Most fishes and 

invertebrates in the GOM are broadly distributed throughout one or more regions of the GOM and, 

typically, only a small portion of a population would be impacted (McEachran, 2009). Studies 

indicate that the impacts of previous accidental spills have not resulted in population-level effects 

(Fodrie and Heck, 2011; Moody et al., 2013; Rooker et al., 2013; Murawski et al., 2014; Fry and 

Anderson, 2014). However, long-term impacts could be masked by many factors (e.g., natural 

population variability, natural and anthropogenic disturbances, and compensatory processes) and 

may not be observed for several years (Fodrie et al., 2014). Therefore, the overall impact to fishes 
4-198 Gulf of Mexico Multisale EIS

and invertebrate resources due to reasonably foreseeable accidental spills resulting from routine 

OCS oil- and gas-related activities is expected to be negligible. 

Cumulative Impacts

The OCS oil- and gas-related activities resulting from a lease sale are assumed to occur 

over a period of 50 years. However, available information is insufficient to conduct an analysis of 

impact-producing factors potentially affecting fish and invertebrate resources over the same period. 

The unknown influence of changing environmental, biological, and anthropogenic factors over such 

an extended period could exceed that of analyzed impact-producing factors. Therefore, this section 

assumes an analysis of reasonably foreseeable cumulative impacts to encompass a period of 

approximately 20 years. This cumulative analysis considers the effects on fishes and invertebrate 

resources of the Gulf of Mexico as a result of the OCS Program, State oil and gas activity, 

recreational and commercial fishing (Chapters 4.11 and 4.10, respectively), and habitat availability. 

Potential degradation of specific habitats is analyzed in Chapters 4.3 (Coastal Habitats), 

4.4 (Deepwater Benthic Communities), 4.5 (Sargassum and Associated Communities), and 4.6 (Live 

Bottom Habitats). The direct and/or indirect impacts from cumulative OCS oil- and gas-related and 

non-OCS oil- and gas-related activities on essential fish habitat are considered and summarized in 

the Essential Fish Habitat Assessment white paper (USDOI, BOEM, 2016d).

OCS Oil- and Gas-Related Impacts

As discussed in the analysis of routine activities, OCS oil- and gas-related activities produce 

some level of anthropogenic sound, though signal characteristics vary widely. Geological and 

geophysical surveys, construction of new facilities, and decommissioning are episodic acoustic 

events and do not contribute to long-term changes in the soundscape. The OCS oil- and gas-related 

support vessel traffic, drilling, production facilities, and other sources of continuous sounds 

contribute to a chronic increase in background noise, with varying areas of effect that may be 

influenced by the sound level, frequencies, and environmental factors (Hildebrand, 2009; 

Slabbekoorn et al., 2010; McKenna et al., 2012). These sources have a low potential for causing 

physiological injury or injuring hearing in fishes and invertebrates (Popper et al., 2014). However, 

continuous sounds have an increased potential for masking biologically relevant sounds than do 

pulsed signals. The potential effects of masking on fishes and invertebrates are unknown, but 

evidence indicates that the increase to background noise as a result of the OCS Program would be 

relatively minor. Therefore, it is expected that the cumulative impact to fishes and invertebrate 

resources in the GOM would be minor and would not extend beyond localized disturbances or 

behavioral modification. The incremental impact of a single lease sale would be negligible. 

Sediment suspended by bottom-disturbing activities settles rapidly to the seafloor. Impacts 

from individual events are temporary, highly localized, and expected to impact small numbers of 

organisms. In nearshore and estuarine waters, the effects of temporarily increased turbidity would 

be indistinguishable from background conditions. Bottom-disturbing activities in outer-shelf and 

oceanic waters may temporarily affect fishes and invertebrates in the water column or bury sessile 

benthic organisms near the disturbance. The cumulative contribution to adverse impacts on these 
Description of the Affected Environment and Impact Analysis 4-199

resources would be negligible due to the transient nature of the disturbance and the limited area 

affected. The incremental impact of a single lease sale would be negligible. 

Cumulative habitat modification as a result of OCS oil- and gas-related activities is spatially 

extensive and long term in nature. It has been hypothesized that the network of OCS oil- and gasrelated infrastructure has resulted in changes in the distribution of some species (Shipp and Bortone, 

2009; Gallaway et al., 2009). However, the total contribution of OCS oil- and gas-related 

infrastructure to hard substrate in the Gulf is small and is projected to decrease throughout the 

period covered by this analysis (Gallaway et al., 2009). Exceptions to the removal requirement may 

be permitted under specific circumstances; for more information, refer to Chapter 3.1.6.2 (Rigs-toReefs Policy) and Chapter 3.3.2.1.2 (Artificial Reefs). The cumulative impact of OCS oil- and gasrelated habitat modification on fishes and invertebrate resources may be extensive for some 

species; therefore, cumulative impacts may range from negligible for most species to moderate for 

those species associated with OCS oil- and gas-related platforms (i.e., distribution and abundance 

may vary from historical values). The incremental impact of a single lease sale would be minor. 

Non-OCS Oil- and Gas-Related Activities

Commercial shipping is the greatest anthropogenic source of low-frequency sound in the 

marine environment and, combined with many other sources (e.g., State oil- and gas-related 

activities, coastal construction, and recreational boating), contributes to increased background noise 

levels; Hildebrand, 2009; McKenna et al., 2012; Hawkins et al., 2014). As a result of increasing 

background noise, fishes and invertebrates may modify behaviors and biologically relevant sounds 

could be masked, but the effects are unknown. Marine organisms evolved in a noisy environment 

and available information suggests that at least some fishes and invertebrates may have the 

capacity to adapt to increasing noise levels (Wardle et al., 2001; Wysocki and Ladich, 2005; Purser 

and Radford, 2011; Radford et al., 2014). However, even organisms adapted to increasing 

background noise could incur consequences from remaining in an environment continuously 

exposed to sound energy from anthropogenic sources. Potential effects would vary among species 

and across a range of environmental factors but may include reduced hatching rates, delayed 

development, or decreased reproductive potential (Slabbekoorn et al., 2010; Hawkins et al., 2014). 

The overall contribution of non-OCS oil- and gas-related anthropogenic sound sources to increasing 

background noise levels in the marine environment is expected to moderately impact fishes and 

invertebrate resources because increased background noise levels affect broad areas and can be 

reasonably assumed to have limited population-level impacts, but they would not be expected to 

result in a long-term decline in population.

The NMFS is responsible for implementing fisheries regulations and managing commercial 

and recreational fisheries, with advice from the regional fisheries management councils. 

Commercial and recreational fishing have been a factor in the decline of several fish populations in 

the GOM (Shipp, 1999; USDOC, NMFS, 2015a; NRC, 2014). Although several stocks are rebuilding 

or have been rebuilt, certain fishing practices and overfishing can have long-term effects on target 

species and the ecosystem. For example, the structure of a rebuilt stock may differ from historic 
4-200 Gulf of Mexico Multisale EIS

demographics, resulting in a less resilient population, or habitat could be altered such that species 

diversity and abundance are affected (Wells et al., 2008; NRC, 2014; Pusceddu et al., 2014; Secor 

et al., 2015). The cumulative impact of long-term, large-scale fisheries activity on fishes and 

invertebrate resources in the GOM is not known, but NMFS has determined that assessed fish 

stocks are predominantly healthy (USDOC, NMFS, 2015a). Thus, it is expected that impacts to 

fishes and invertebrate resources as a result of commercial and recreational fisheries would range 

from negligible for most nontargeted species to moderate for species that are overfished or 

experiencing overfishing (e.g., hogfish spp., gray triggerfish, and greater amber jack [Seriola 

dumerili]).

The conversion or modification of wetlands as a result of agricultural, residential, and 

commercial development in the GOM has been substantial (USEPA, 2012b; Greene et al., 2014). 

The trend for coastal development is projected to continue into the future, although at a slower rate 

because of regulatory pressures (refer to Chapter 4.3, Coastal Habitats, for detailed information on 

these habitats, potential impacts, and mitigations). The conversion of habitat from one form to 

another (e.g., wetlands to open water) would typically result in community-level changes in 

biodiversity and abundance compared with communities in unmodified habitat (Lowe and Peterson, 

2014; USDOC, NMFS, 2010a). Although changes to habitat may benefit some species while 

adversely impacting others, it is generally accepted that the quality (i.e., the ecological services 

provided) of modified habitat is not equivalent to natural habitat (Peterson and Lowe, 2009; 

Scyphers et al., 2015). Therefore, the continued loss or modification of wetlands could ultimately 

result in decreased recruitment for some estuarine-dependent species, adversely impacting stocks 

within the region (Levin and Stunz, 2005; Jordan et al., 2012). The current lack of a meaningful 

baseline makes it extremely difficult to estimate cumulative impacts to fishes and invertebrate 

resources at a regional scale. However, coastal zone management efforts increasingly incorporate 

the responses of fishes and invertebrates into analyses of development activities (Peterson and 

Lowe, 2009; Greene et al., 2014). The Federal, State, and local agencies jointly responsible for 

managing estuarine habitats, permitting development, and mitigating impacts ensure that 

sustainable development practices are implemented. Therefore, the cumulative adverse impact of 

coastal development on fishes and invertebrate resources is expected to be minor. 

Additional pressures potentially contributing to cumulative effects on fishes and invertebrate 

resources in the GOM include increasing invasive species populations and climate change. These 

factors are currently negligible but could have increasingly substantial impacts in the future. Invasive 

species, such as the lionfish, have the potential to out-compete and displace some indigenous 

species of ecological, commercial, and/or recreational importance (Morris and Akin, 2009; Dahl and 

Patterson, 2014; Raymond et al., 2014). Although severe weather events are part of the natural 

environment and are not considered in an analysis of impact-producing factors, changing conditions 

that alter the frequency and/or severity of weather events or that accelerate sea-level rise could 

impact fishes and invertebrate resources in an unforeseen manner. A review of climate change is 

presented in Chapter 4.2.1 of the Five-Year Program EIS (USDOI, BOEM, 2016b).
Description of the Affected Environment and Impact Analysis 4-201

The cumulative effect of combined past, present, and reasonably foreseeable future OCS oiland gas-related activities and non-OCS oil- and gas-related activities on fishes and invertebrate 

resources of the Gulf of Mexico is expected to vary spatiotemporally. The incremental contribution 

of OCS oil- and gas-related activities to the combined cumulative impacts is generally minor in 

comparison with all other human activities affecting the resources. Impacts to fish and invertebrate 

populations are expected to be in proportion to the fraction of a population exposed to an impactproducing factor. Therefore, OCS oil- and gas-related habitat modification is likely to have a greater 

impact than other oil- and gas-related impact-producing factors of a more limited scale and duration. 

However, impacts are not universally adverse and some habitat modification may benefit particular 

species or communities. Commercial and recreational fishing are expected to have the greatest 

direct impact on fishes and invertebrate resources. Although the NMFS manages fisheries, 

populations are affected by many biological and environmental factors. Fluctuations in populations 

of fisheries-affected species are expected. Increased background noise levels due to anthropogenic 

sources, such as commercial shipping, are also likely to affect deep waters of the GOM (Hildebrand, 

2009). Although the effects are currently unknown, no impacts to fish and invertebrate populations 

in the GOM have been quantified. International efforts to develop and implement ship-quieting 

technologies may mitigate future increases in shipping capacity. As a result of these impactproducing factors, the overall cumulative impact on fishes and invertebrate resources may range 

from negligible to moderate for different species throughout the period analyzed.

Incomplete or Unavailable Information

BOEM identified incomplete or unavailable information related to impacts to fishes and 

invertebrate resources resulting from OCS oil- and gas-related activities and non-OCS oil- and gasrelated activities in the GOM. Anthropogenic sound and habitat modification directly or indirectly 

affect large areas of the GOM and potentially impact thousands of species. However, the response 

of individuals, groups of conspecifics (members of the same species), and communities are highly 

variable and inconsistent. In addition, BOEM recognizes that there is incomplete information with 

respect to potential long-term effects resulting from exposure to spilled oil. Although additional 

information on these impact-producing factors may be relevant to the evaluation of impacts to fishes 

and invertebrate resources, BOEM has determined that the incomplete information is not essential to 

a reasoned choice among alternatives. Analyses of routine activities, accidental events, and 

cumulative impacts drew upon the most current and best available research to assess the potential 

effects on many species and habitats. The findings collectively indicate that impacts are likely, but 

limited, and are not expected to induce a population-level response. BOEM recognizes the potential 

that populations with spatially limited distributions or increased sensitivity to an impact-producing 

factor may be more severely impacted than current research suggests. However, sufficient data to 

conduct a thorough assessment of all potentially affected species are not available or obtainable 

within the timeline contemplated in the NEPA analysis of this Multisale EIS. BOEM used the best 

available science to determine the range of reasonably foreseeable impacts and applied accepted 

scientific methodologies to integrate existing information and extrapolate potential outcomes in 

completing this analysis and formulating the conclusions presented here.
4-202 Gulf of Mexico Multisale EIS

4.7.2.1 Alternatives A, B, C, and D

With respect to fishes and invertebrate resources, the effects associated with selection of 

any of the proposed action alternatives would be equivalent because of the diversity and distribution 

of fish and invertebrate species throughout the potential area of interest. The preceding analyses 

assumed a nonrandom distribution of species and considered impacts to fishes and invertebrate 

resources occurring in a wide range of habitats across all planning areas. While the WPA is a 

smaller area with less projected activity than is proposed for the CPA/EPA (refer to Chapter 3), the 

distribution of fishes and invertebrate species is nonrandom and generally even throughout their 

range of habitat within the planning areas. As such, the potential for impacts to populations is 

independent of the planning area(s) analyzed. Differences in the specific populations potentially 

exposed to impact-producing factors and the potential impacts may be more easily estimated as 

specific sites and activities become known. Therefore, at a planning area scale, it is expected that a 

similar mix of species would be exposed to the analyzed impact-producing factors, regardless of the 

specific action alternative selected. The activities proposed under Alternatives A, B, C, and D would 

directly impact fishes and invertebrate resources within the GOM and would contribute incrementally 

to the cumulative effects on these resources. Routine activities, excluding infrastructure 

emplacement, would be expected to have short-term and/or localized effects. The installation of 

OCS oil- and gas-related infrastructure constitutes a long-term modification of the local habitat. 

Individually, these modifications have small-scale (e.g., community-level) effects on the distribution 

and abundance of species; cumulatively, OCS oil- and gas-related infrastructure is hypothesized to 

have moderately impacted the distribution of some fishes and invertebrates, exceeding natural 

variations. Although this effect is not necessarily adverse and infrastructure is expected to be 

decommissioned and sites restored to natural habitat, the cumulative impact over the life of the OCS 

Program is spatiotemporally extensive with species-specific effects. Accidental spills are considered 

low-probability events, but they have the potential to produce localized impacts on fishes and 

invertebrate resources if coinciding with a spawning event. Mobile adults are expected to avoid 

adverse conditions, limiting exposure to spilled oil. The cumulative, long-term effects of exposure to 

oil are unknown, but available information suggests that the effects have been minor. The 

cumulative effects of habitat loss and increasing background noise levels are unknown, but the OCS 

oil- and gas-related contribution is small, relative to non-OCS oil- and gas-related impact-producing 

factors. Therefore, the analysis of routine OCS oil- and gas-related activities, accidental events, and 

the cumulative impacts of OCS oil- and gas-related and non-OCS oil- and gas-related activities 

indicates the expected overall impact to fishes and invertebrate resources, depending upon the 

affected species, would range from negligible to moderate for the period analyzed. For example, 

muds and cuttings discharged at the surface for a well drilled at a water depth of 5,000 ft (1,524 m) 

would have a negligible impact on coastal species, such as menhaden, whereas a small spill in 

coastal waters and subsequent response activities could disrupt a spawning event or temporarily 

displace coastal fishes from the affected area (minor). Moderate impacts would only be expected if 

impact-producing factors affected habitat or populations to an extent that would be expected to 

exceed natural variations in population abundance or distribution but not result in a long-term 

decline.
Description of the Affected Environment and Impact Analysis 4-203

4.7.2.2 Alternative E—No Action

Under Alternative E impacts on fishes and invertebrate resources within the Gulf of Mexico 

would be none. However, cumulative impacts would be unchanged from the conclusions reached 

for the other alternatives.

4.8 BIRDS

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

with a GOM proposed action and a proposed action’s incremental contribution to the cumulative 

impacts to coastal and migratory birds are presented in this chapter. The approach of the analysis is 

to focus on the potential impact-producing factors from OCS oil- and gas-related routine activities 

(i.e., exploration, development, and production), as well as accidental events and cumulative 

impacts, and to define the impact levels for each impact-producing factor (Table 4-11). The impactproducing factors considered and analyzed include discharges and wastes, noise, platform 

severance with explosives, geophysical surveys with airguns, platform presence and lighting, 

emergency air emissions, platform or pipeline oil spills, spill response, oil- and gas-related activities 

in State waters, the hypoxic “dead zone” of the Mississippi River, net coastal wetland gain or loss, a 

large tanker spill, military activities, recreation, boat traffic, impacts on bird habitat, collisions with 

manmade structures, predation by domestic cats, commercial fishing, climate change, and wetland 

subsidence.

Impact-producing factors considered but not analyzed include obstruction lighting, which is 

under the jurisdiction of the USCG. Other impact-producing factors that were not analyzed because 

they do not apply to birds include geological ancillary activities, all onshore infrastructure 

emplacement and presence, offshore platform emplacement, other commissioning activities, and 

onshore waste disposal.

Seven species found in the area of interest are listed under the ESA, and BOEM has initiated 

formal consultation with the FWS for those species. Those species have life histories that are 

similar to those of the birds covered in this chapter, but the cumulative impact could be greater. 

BOEM recognizes this, consults on these species, and requires mitigations that would decrease the 

potential for greater impacts due to small population size. For more information on the listed bird 

species, refer to Chapter 4.9.4 (Protected Birds).
4-204 Gulf of Mexico Multisale EIS

Table 4-11. Birds Impact-Producing Factors.

Birds Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Discharges and 

Wastes Negligible Negligible Negligible Negligible None

OCS Oil- and GasRelated Noise and 

Disturbance

Negligible Negligible Negligible Negligible None

Platform Severance 

and Rigs-to-Reefs Minor Minor Minor Minor None

Geophysical Surveys 

with Airguns Minor Minor Minor Minor None

Platform Presence 

and Lighting Minor Minor Minor Minor None

Accidental Impacts

Oil Spills Moderate Moderate Moderate Moderate None

Oil-Spill Response Minor Minor Minor Minor None

Emergency Air 

Emissions Minor Minor Minor Minor None

Cumulative Impacts

OCS Oil- and GasRelated Moderate Moderate Moderate Moderate Moderate

Non-OCS Oil- and 

Gas-Related Major Major Major Major Major

Impact-Level Definitions

In ecology, the size of a population is often defined by the number of individuals with similar 

genes (i.e., species, subspecies, and races). However, a population can also be somewhat more 

arbitrarily defined as individuals in a geographic area. That area is sometimes of arbitrary location or 

size. Birds species described in this chapter are considered to have large populations because they 

are not endangered or threatened and because each species, taken as a whole, is widely distributed 

and abundant. The impact-level definitions for birds are as follows:

• Negligible – Overall, there would be little to no impacts that are measured or 

measurable for a population. No mortality of a flock or large population would 

occur, and no overall disturbance-causing changes in behavioral patterns would 

be expected.

• Minor – One of the two following conditions are met: (1) flocks or large 

populations of birds would experience stimuli or impact-producing factors and 

would be disturbed or otherwise affected overall, resulting in acute behavioral 

changes; however, these impacts would be short-term and reversible; and 

(2) one or more incidents where one or more individuals experience injury or 
Description of the Affected Environment and Impact Analysis 4-205

mortality may occur, but with no measured or measurable impact on a large 

population.

• Moderate – A large population of birds would experience stimuli or impactproducing factors and overall would be chronically disturbed or affected, which 

could result in chronic behavioral changes. Impacts would affect substantial 

numbers of individuals but would not affect estimates of continued population 

viability, including predicted annual rates of recruitment or survival. Sublethal 

impacts would be irreversible at this impact level.

• Major – A large population of birds would experience stimuli or impact-producing 

factors that would result in a reduction in the estimates of continued viability of 

the population. Major impacts could include sufficiently high numbers such that 

the estimated continued viability of a large population is diminished, including 

predicted massive reductions in the annual rates of recruitment or survival. 

Major impacts could also include permanent disruption of behavioral patterns that 

would affect at least one whole species.

4.8.1 Description of the Affected Environment

This description of birds focuses on the factors that control the relative vulnerability of 

different bird groups to impacts. Passerines, or songbirds, represent many of the breeding and 

wintering birds within the Gulf Coast States. They are only found offshore when migrating across 

the Gulf of Mexico, and they cannot stop and rest or feed on the water. Some species of birds

(some seabirds) live primarily offshore except when breeding and, therefore, are rarely observed in 

the nearshore environment. The remaining species are found within coastal and inshore habitats 

and may be more susceptible to potential deleterious effects resulting from OCS oil- and gas-related 

activities because many of these species largely overlap spatially and temporally with OCS oil- and 

gas-related activities because of their abundance or density, and because of the potential of oil 

impacting their habitat or food resources. A detailed analysis of the impacts to birds is presented in 

the chapters below.

Feeding Habits

A bird’s feeding method is one of the important determinants of a bird’s habitat choice. Bird 

species feed either in the water (aquatic feeders) or terrestrially. Aquatic bird species that feed by 

wading include some shorebirds and other waders such as herons. Some species wade in relatively 

shallow water to feed and others feed on beaches and have relatively short legs; other species feed 

in relatively deeper water as well as relatively shallow water and have relatively longer legs. 

Shorebirds are adapted to take advantage of tidally-influenced habitat. Their diurnal movements 

and habitat use appears to be closely linked to tidal advances and recessions, i.e., lunar, solar, or 

wind-driven tides. Shorebirds and other wading species feed on invertebrates and fish. Aquatic bird 

species, including some ducks, may feed by dabbling at the water surface. Many aquatic bird 

species, including some ducks and many seabirds, feed by diving into the water from the air or water 
4-206 Gulf of Mexico Multisale EIS

surface for either plant or animal food. Some seabirds aggregate at patches of floating macroalgae 

Sargassum to feed or rest, at least in tropical waters (Haney, 1986).

Oil from reasonably foreseeable spills is not expected to be very commonly encountered by 

birds. Still, birds are a relatively vulnerable resource because feeding habits may result in 

encounters between birds and OCS oil- and gas-related activity. For example, waders feed in 

shallow water, which is important because oil from previous spills that happened to reach the 

sediment may accumulate in the sediment, where birds may encounter it. Diving birds can 

encounter an oil slick either if they begin their dive in the air and pass across the water surface or if 

they begin their dive floating on the water surface. Birds may feed and roost in the water or at or 

near the water’s edge, where they may be impacted by oil spill. Marsh birds feed in or at the water’s 

edge of marshes, where oil may accumulate in the sediment. Also, platforms may represent 

profitable foraging areas for seabirds, raptors, and potentially passerines (Wiese et al., 2001; 

Russell, 2005).

Habitat

The open Gulf (including blue water [off the continental shelf], shelf, and inshore open water) 

is used by terrestrial birds (including passerines), shorebirds, long-legged wading birds, and raptors 

for trans-Gulf migration (Russell, 2005). This habitat is used by seabirds for feeding and roosting, 

and some seabirds never come ashore in the Gulf of Mexico. Wetlands (consisting of trees, shrubs, 

marshes, and/or unvegetated flats) (refer to Chapter 4.3, Coastal Habitats) are used by waterfowl, 

shorebirds, long-legged wading birds, secretive marsh birds (e.g., rails), raptors, and terrestrial birds 

(including passerines) for feeding, roosting, and/or nesting (Portnoy, 1978 and 1981; Hunter et al., 

2006; Brown et al., 2001; and North American Waterfowl Management Plan, 2004). Beaches and 

dunes are used by seabirds and shorebirds for feeding, roosting, and/or nesting (Portnoy, 1978 and 

1981; Hunter et al., 2006). Coastal forests are used by trans-Gulf migrant terrestrial birds for 

feeding, roosting, and/or nesting. Several species breed along the coastline of the Gulf of Mexico 

(where spilled oil may travel and persist) and, therefore, may be especially vulnerable to the impacts 

of an oil spill. Previous surveys indicate that Louisiana, Texas, and Florida are among the primary 

states in the southern and southeastern U.S. for both nesting colonies and the total number of 

breeding coastal and marine birds (Portnoy, 1978 and 1981; Hunter et al., 2006). All avian species 

show varying levels of fidelity to both breeding and wintering areas.

Population Ecology

The level of any impact to different species of birds depends on its population ecology, 

including the age or life stages and sex that are impacted. For example, relevant population ecology 

information for seabirds includes delayed maturity, low reproductive potential, periodic nonbreeding, 

low first-year survival, and small clutch size. These factors can make them the most vulnerable to 

impacts. Relevant population ecology is not always available to explain oiling mortality from an oil 

spill because the sex and life stage of recovered oiled birds is not always known or recorded. For 

example, for the Deepwater Horizon explosion, oil spill, and response, only the species information 

was available, not the age, life stage, or sex of oiled birds. The location, magnitude, and other 
Description of the Affected Environment and Impact Analysis 4-207

conditions of an impact-producing factor that may seem to have relatively low contact with and 

relatively reduced mortality for one species may in fact cause other bird species increased mortality 

and long-term impacts. Populations appear to be most sensitive to changes (even small decreases) 

in adult survival, particularly female survival because adult female survival appears to be the driver 

for these populations (Russell, 1999).

Migration

Some birds that utilize the GOM are year-round resident species. These species may be 

exposed to impacts during any time of the year. However, most of the bird species that utilize the 

GOM are migratory. They may breed, overwinter, or stop over in the GOM while migrating on the 

northern Gulf Coast. For example, some birds may breed on the coast and depart during the winter 

months. However, some birds breed in the northern United States or the Caribbean and overwinter 

offshore the GOM and never come ashore. All avian species show varying levels of fidelity to both 

breeding and wintering areas. Birds may be present only during one or two of the following seasons: 

breeding and/or overwintering and/or migrating. Therefore, seasonal timing of an impact helps 

determine which species would be affected.

Each spring, vast numbers of birds migrate northward across the GOM enroute to breeding 

habitats in the United States and Canada from their wintering quarters in the neotropics. They 

depart in large numbers from the Yucatan Peninsula and the Isthmus of Tehuantepec (Russell, 

2005). The path they take depends on supporting tail wind direction, which depends, in turn, on the 

presence of an East Continental High Pressure synaptic weather pattern over the continental United 

States or a Bermuda High Pressure synaptic weather pattern over the Atlantic Ocean around 

Bermuda (Russell, 2005). The East Continental Highs move east and become Bermuda Highs. 

During an East Continental High, the birds may migrate especially from the east-southeast to the 

northwest Gulf of Mexico (Figure 4-20). During a Bermuda High, the birds may migrate especially 

from the south-southeast to the northcentral Gulf of Mexico (Figure 4-21). They are mostly seed 

eaters and insectivores and, therefore, may stop over and feed on available insects but mostly not 

on aquatic organisms. Following a short breeding season in the north, most of these birds return 

southward across the GOM; their numbers are then augmented by offspring produced over the 

summer (Russell, 2005). An example of a fall migration route that could initiate in the north central 

Gulf of Mexico and terminate on the eastern Bay of Campeche, the Yucatan Peninsula, western 

Cuba, and northern Honduras is shown in Figure 4-20. Migrating songbirds may stop over on 

offshore platforms. Platform density with respect to migratory routes is shown in Figure 4-22, and 

its high spatial variability at a large scale suggests that the probability of a bird encountering one or 

more platforms is also highly variable of routes at a large scale. Migratory birds may also stop over 

on boats, other vessels, and coastal terrestrial habitat when crossing the GOM in the spring or fall. 

Three of the four migratory flyways in the United States depend on the GOM as part of their route. 

Executive Order 13186 protects migratory birds and emphasizes species of conservation concern. It 

requires analyses of birds in NEPA documents and a Memorandum of Understanding between the 

action agency (BOEM and BSEE) and the FWS. Also, all migratory birds are protected under the 
4-208 Gulf of Mexico Multisale EIS

Migratory Bird Treaty Act. The Act provides limits on when migratory birds can be taken, killed, 

possessed, transported, or imported.

For some bird species, both spring and fall migrations take place in a series of stops among 

various staging areas. At these staging areas, birds spend time primarily feeding to recover 

reserves necessary for the sustained flight to the next staging area (Norris, 2005; Krapu et al., 2006; 

Skagen, 2006). Many coastal habitats along the GOM are critical for such purposes.

Figure 4-20. Migration Routes for Trans-Gulf Migratory Birds in the Presence of an Eastern 

Continental High. (The Eastern Continental High is indicated by the letter "H," and the 

corresponding clockwise somewhat concentric synaptic wind patterns are indicated by 

lines and arrows.)
Description of the Affected Environment and Impact Analysis 4-209

Figure 4-21. Migration Routes for Trans-Gulf Migratory Birds in the Presence 

of a Bermuda High. (The Bermuda High is indicated by the letter 

"H," and clockwise somewhat concentric synaptic wind patterns 

are indicated by lines and arrows.)

Figure 4-22. Platform Density and Spring Migration Routes for Trans-Gulf 

Migratory Birds.
4-210 Gulf of Mexico Multisale EIS

Baseline Populations

Baseline populations of birds have been affected by recent events, including hurricanes and 

the Deepwater Horizon explosion, oil spill, and response. However, no species or subspecies of 

birds that has been listed as federally endangered or threatened, of conservation concern to the U.S. 

Fish and Wildlife Service, State listed, or of State conservation concern has been reported in sharp 

decline or otherwise harmed by either recent hurricanes or the Deepwater Horizon explosion, oil 

spill, and response. Most populations are not listed of conservation concern and, therefore, the 

populations are probably, but not absolutely, low or in sharp decline. No hurricanes have made 

baseline changes since the 2012-2017 WPA/CPA Multisale EIS, which was published in 2012 

(USDOI, BOEM, 2012b). There is new information on baseline changes resulting from the 

Deepwater Horizon explosion, oil spill, and response.

Hurricane-related flooding can drown nests, and associated winds can kill birds due to 

impact with objects like trees. In addition, hurricane impacts to coastal ecosystems can have 

deleterious effects to foraging and nesting birds that utilize those habitats. However, no surveys of 

mortality from such impacts related to Hurricane Katrina and other storms were located.

Mortality from the Deepwater Horizon explosion, oil spill, and response was sufficient to 

cause a small negative shift in baseline abundances for seabirds. Total seabird mortality seaward of 

25 mi (40 km) 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 were 

60,000-15,000,000 for four procellariiform (shearwaters and related) species, 9,000 for one 

pelecaniform (pelican and related) species, and 96,000-500,000 for three charadriiform (gulls and 

related) species (Haney et al., 2014a). Total bird mortality landward of 25 mi (40 km) from shore 

was estimated as 600,000 birds using one model and 800,000 birds using another (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 GOM (Haney et al., 2014b). This new information estimates a 

small negative shift in baseline numbers. No recovery data have become available since the 

analyses by Haney et al. (2014a and 2014b). Incremental impacts caused by the negative shift in 

baseline numbers were not sufficient to change the conclusions for the impact analysis of a 

proposed action. The shift was extrapolated from the increased mortality due to the Deepwater 

Horizon explosion, oil spill, and response. However, these changes to the baseline did not identify 

any species whose population was likely to be impacted by a proposed action or alternatives. 

Mortality can indicate substantial impacts from an oil spill even when sharp declines or other impacts 

on population size have not been measured. No reports of the impact of hurricane levels or the 

impact of the Deepwater Horizon explosion, oil spill, and response on the rates of population decline 

or any other impacts on population size were located.

4.8.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from the 

routine activities, accidental events, and cumulative impacts described in Chapter 3 and their 
Description of the Affected Environment and Impact Analysis 4-211

potential effects on birds that would potentially be impacted by a proposed action or the alternatives. 

This analysis would apply to all alternatives considered; however, the level of impacts would be 

different for each alternative, as discussed below in Chapters 4.8.2.1-5. 

Routine Activities

Impacts from routine activities to coastal, marine, and migratory birds include impacts from 

routine discharges and wastes, noise, platform severance with explosives (barotrauma), geophysical 

surveys with airguns, platform presence and lighting, construction of OCS-related onshore facilities, 

and pipeline landfalls.

Discharges and wastes (Chapter 3.1.5) include produced waters, drilling muds and cuttings, 

and routine air emissions. Routine discharges and wastes affecting air and water quality (Chapter 

4.1, Air Quality, and Chapter 4.2, Water Quality) are under the jurisdiction of the USEPA or BOEM, 

and regulation assures that impacts are negligible. For air quality, mandated timetables and other 

requirements necessary for attaining and maintaining healthful air quality in the U.S. are imposed 

based on the seriousness of the regional air quality problem detected by monitoring. BOEM is 

characterizing OCS oil- and gas-related operational discharges and wastes as having a negligible

impact on birds because of regulations on air emissions and also because effluents into water are 

regulated under the NPDES with discharge limits that are risk-based and supported by toxicity 

testing.

The OCS oil- and gas-related helicopters and vessels have the potential to cause noise and 

disturbance. However, flight altitude restrictions over sensitive habitat, including that of birds, may 

make serious disturbance unlikely. Birds are also known to habituate to noises, including airport 

noise. The OCS oil- and gas-related vessel traffic would follow regular routes so seabirds would find 

the noise to be familiar. Therefore, the impact of OCS oil- and gas-related noise from helicopters 

and vessels to birds would be expected to be negligible. 

Platform severance and Rigs-to-Reefs are discussed in Structure-Removal Operations on 

the Gulf of Mexico Outer Continental Shelf: Programmatic Environmental Assessment (USDOI, 

MMS, 2005). Refer to Chapter 3.1.6 for more information on platform removal. Platform severance 

with explosives may potentially kill one or more birds from barotrauma if a bird (or several birds 

because birds may occur in a flock) is present at the location of the severance. For the impact of 

underwater sound, a threshold of 202 dB sound exposure level (SEL) for injury and 208 dB SEL for 

barotrauma was recommended for the Brahyramphus marmoratus, a diving seabird (USDOI, FWS, 

2011). Platform relocation in the Rigs-to-Reefs program would potentially provide foraging habitat 

for birds, which would be a positive impact. The overall impact of severance and rigs-to-reefs would 

be minor. 

Geological and geophysical (G&G) surveys are discussed in the Atlantic OCS Proposed 

Geological and Geophysical Activities: Mid-Atlantic and South Atlantic Planning Areas; Final 

Programmatic Environmental Impact Statement (USDOI, BOEM, 2014a). Refer to Chapter 3.1.2.1
4-212 Gulf of Mexico Multisale EIS

for more information on G&G information in the GOM. Geological and geophysical surveys with 

airguns may kill one bird (or a small number of individuals occurring in a flock) from barotrauma in 

one or more incident. This impact would be minor. 

Potential impacts of platform lighting can be dependent on spectra, intensity, and weather 

conditions (refer to Chapter 3.1.3.4.3 for more information on platform lighting). Obstruction lighting 

is considered under cumulative impacts because it is under the jurisdiction of the USCG and not 

likely subject to change. Birds may have the following behaviors in any combination, any order, any 

frequency, and any duration at platforms: resting; feeding; collision with platforms; and nocturnal 

circulation (Russell, 2005). Seabirds are attracted to structures and may benefit from underwater 

reef organisms associated with the structure. Nocturnal circulation happens to some birds stopping 

at platforms. At night, birds circulate around the lit platforms, sometimes for extended periods. 

Nocturnal circulation may be brief with little impact or may be long term and burn up energy reserves 

(Russell, 2005). Song birds become restless to migrate at dusk and lose migratory restlessness 

when they stop to feed. Therefore, if they stop and feed, they may not continue on until dusk 

happens again. If they just stop and do not feed, they may continue on soon after stopping. The 

number of times a bird stops at platforms is unknown. Birds would likely stop over on platforms with 

lights with spectral red or with high intensity during overcast, rainy, or foggy conditions at night 

(Marquenie et al., 2013). Also, they might stop over if they encounter head winds that slow their 

trans-Gulf migration past dawn. The cause-and-effect processes of possible impacts from lights to 

migratory birds and migration are being investigated; however, no determinations have been made. 

This is because the bird optical magnetic compass, which may be key to birds’ response to lights, 

has been very difficult to study; its properties are mostly conjecture at this time (Wiltschko and 

Wiltschko, 2014; Ramirez et al., 2014) and have been investigated by wildlife biologists teamed with 

quantum chemists. 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 (i.e., 

made more fit). The potential range of a bird adapted to fatten up enough to cross extensive barriers 

like the open ocean or GOM is 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 non-stop range of a bar-tailed godwit leaving Alaska (based on a model of fuel 

load) was to the South Pole (Pennycuick and Battley, 2003). Small populations of birds may be 

affected, which may affect species richness (community structure). That may, in turn, affect bird 

watching and bird hunting as economically valuable activities. Injury or mortality at the small 

population level for a long term (10+ years) with almost full recovery means that impacts to transGulf migrants would be minor. Minor impacts would result partly because estimated annual 

mortality from collisions due to structure presence has been estimated at 200,000-321,000 birds of 

the up to 316 million birds that migrate (Russell, 2005). Impacts on trans-Gulf migrants from 

platform presence and lighting need further study of both positive and negative effects to be 

precisely assessed. The OCS oil- and gas-related construction of onshore facilities would require 

obtaining permits for any projects that could harm wetlands or any other habitats protected by 

conservation laws and regulations. For example, construction in a wetland area would require a 

COE permit under Section 404 of the Clean Water Act; this would include mitigations and monitoring 

of the activities. Further reinforcement of wetland protection is expected because of the long-
Description of the Affected Environment and Impact Analysis 4-213

standing goal of no net wetland loss. As a result, negligible impacts from OCS oil- and gas-related 

construction of onshore facilities and the resulting habitat loss to birds are expected.

Impacts from a pipeline landfall could disturb shoreline or wetland habitat that is utilized by 

birds. The resulting habitat loss to birds from installation method of directional drilling is expected to 

result in a negligible impact.

Accidental Events

Impacts for accidental events to birds are caused by oil spills, spill cleanup, and emergency 

air emissions. Impacts of hydrocarbons from oil spills depend on the hydrocarbons’ ultimate 

destination, i.e., in the air (from evaporation), in the water, or in the sediment. Birds may be affected 

by hydrocarbons through means of inhalation. They may also be affected by hydrocarbons through 

means of ingestion when eating oiled benthic, planktonic, or pelagic prey; preening oiled plumage; or 

drinking hydrocarbons in water. Prey may be killed by oiling. Oiled plumage causes loss of 

insulation and buoyancy. While some birds can be rehabilitated after contamination by oil or 

dispersants, others may sustain injuries or die. Oil and dispersants can affect birds at the small 

population level. Birds that feed aquatically are vulnerable to oil, and migrants or residents that 

occur in the GOM when oil from a spill is present are also vulnerable. These circumstances are 

discussed in detail in Chapter 4.8.1. Impacts on long-lived seabirds can last longer because 

generation time is longer and can have delayed impacts (e.g., a delay on first-breeders would have a 

delayed reduction in recruitment), which would go unnoticed until years after exposure; therefore, 

detection would not occur without long-term studies. In addition, oiling may sometimes be more 

severe in shallow water, wetlands, and shorelines where avian diversity and abundance, as well as 

hydrocarbon accumulation and persistence, may be high. Refer to Chapter 4.3 (Coastal Habitats) 

for a discussion of the fate of oil in wetlands. Sometimes, because of lack of adequate personnel 

training or the sheer scale of activity, shoreline cleanup (Chapter 3.2.7) may disturb nesting birds 

and have a minor impact. Disturbance to GOM nonnesting shorebirds from the Deepwater Horizon 

oil-spill cleanup may have affected bird conditions later on the northern breeding grounds (Henkel 

et al., 2014). An oil-spill sublethally affecting birds that migrate may have carry-over impacts to one 

or migratory destinations, including the ecosystems at those destinations.

Long-term impacts are possible to seabirds (with long generation time) that delay first 

breeding (and hence impacts on first breeders would have a delayed reduction in recruitment) 

(Dunnet et al., 1982). Long-term impacts also occur when local population extirpation occurs, 

resulting in loss of species richness (community structure) until a colony or other small population 

can recover from extirpation. Refer to Chapter 4.12 (Recreational Resources) for a discussion of 

the socioeconomics of wildlife tourism. Finally, long-term impacts occur when oil persists 

(sometimes for years) in sediment and may contact seafloor organisms or be resuspended and 

contact organisms in the water column. Resuspended oil may then be transported to other areas 

and settle out where it could be encountered by birds. The impact level from oil spills would depend 

on the combined result of the effects on habitat (sediment oiling in shallow water) and abundance 

(effect on small populations) of affected birds, as well as long-term persistence of oil in some 
4-214 Gulf of Mexico Multisale EIS

habitats. A minor offshore spill (<1,000 bbl) could disappear even before a crew could arrive and 

clean it up; therefore, impacts would be negligible. A minor inshore spill (e.g., <1,000 bbl spilled 

during vessel refueling) could be completely cleaned up right away; therefore, impacts would be 

negligible. Impacts of a large spill (≥1,000 bbl) associated with a proposed action under Alternative 

A, B, C, or D would be expected to be moderate because a large population of birds would be 

chronically disturbed or affected, because of the size and persistence of the oil spill.

Combined probabilities of occurrence and contact of an oil spill with shoreline bird species 

and nearshore bird species can be found in Figures E-2 through E-7 and Figure E-20, 

respectively. Seabirds may take longer to recover from the impacts of an oil spill than other bird 

groups because of their unique population ecology (demography), regardless of the intensity of the 

initial impacts on a population.

Emergency air emissions may cause various toxic effects to a bird or flock of birds exposed 

to the discharge. An example would be a hydrogen sulfide leak from a pipe. A single incident of 

toxic effects could affect nothing more than a flock; therefore, impacts from emergency air emissions 

would be minor. 

Cumulative Impacts

OCS Oil- and Gas-Related Impacts

Routine OCS oil- and gas-related impacts that could add to the cumulative impacts to coastal 

and marine birds are effects to air and water quality, noise, platform severance with explosives 

(barotrauma), geophysical surveys with airguns (barotrauma), platform presence and lighting, and 

construction. They are discussed in detail in the “Routine Activities” section above. Accidental 

events are oil spills, cleanup, and emergency air emissions, which are discussed in the “Accidental 

Events” section above. Cumulative OCS oil- and gas-related impacts are presented briefly here.

Impacts from routine air and water discharges are discussed in Chapters 4.1 (Air Quality) 

and 4.2 (Water Quality). As a result of these discharges, impacts on birds would be expected to be 

negligible. Drilling discharges, produced waters, and the discarding of marine trash and debris 

would have negligible impacts on birds. Impacts of aircraft and vessel noise would be expected to 

be negligible. Impacts of severance with explosives during platform decommissioning and of 

geophysical surveys with airguns would have minor impacts. Structure presence would possibly 

result in collision of birds with a structure, nocturnal circulation, or an opportunity to rest and/or feed. 

It may have a net beneficial or a net negative impact on birds (Ramirez et al., 2014; Marquenie et al., 

2013). Structure presence is discussed in the “Incomplete or Unavailable Information” section 

below. Impacts of coastal OCS oil- and gas-related facility construction would be expected to be 

negligible. A large oil spill (≥1,000 bbl) could moderately impact coastal and marine birds, and oilspill response and emergency air emissions could have minor impacts on them; refer to the 

“Accidental Events” section above for more details. Modeling shows that, without a thorough 

understanding of a species’ habitat use and preferences, a species’ ability to locate and colonize 

alternative habitat, and the population structure, it is difficult to make inferences regarding the ability 
Description of the Affected Environment and Impact Analysis 4-215

of individual birds or groups to successfully emigrate and colonize novel, undisturbed habitat 

(assuming it is available) (Fahrig, 1997, 1998, and 2001). BOEM used scientific reasoning about 

habitat in lieu of empirical studies to help understand the impacts of oil spills on colonial nesting 

birds. Habitat may be occupied at or below carrying capacity, or it may not be occupied at all, so it 

may have various amounts of room for immigrant birds (and various sources of mortality or 

depression of realized reproductive rate) when immigrants are escaping disturbance or an oil spill. 

For habitat that is occupied, any single patch or group of patches of habitat may change periodically 

in the resource or resources (which could include the amount of the habitat itself) that are limiting to 

its occupants. The impact of an area of major degradation of habitat quality (with no change in total 

habitat area) can be more or less important than the impact of complete loss of a large area of 

habitat. For purposes of this discussion, habitat availability is defined as presence of unoccupied 

habitat. The following statement applies only if birds are able to move into habitat that is occupied 

below carrying capacity. Habitat does not become limiting until it is filled up (completely occupied), 

so habitat availability is not itself limiting. Filled habitat (habitat limitation) can be ideal for birds if 

that is the pervasive condition of a bird population. Filled habitat only becomes a problem when no 

extra space is available for immigrants trying to escape a major event such as an oil spill or when 

the amount of filled habitat is so small that a bird is listed as threatened, endangered, or of 

conservation concern. Unoccupied habitat for colonial nesting birds is likely pervasive because 

periodic surveys of bird colonies in the northern Gulf of Mexico show regular formation of completely 

new bird colonies. Therefore, impacts of an oil spill on colonial nesting birds are expected to be 

negligible. Impacts from pipeline landfalls are expected to be negligible. 

Non-OCS Oil- and Gas-Related Impacts

All OCS oil- and gas-related impact-producing factors and their impact levels also hold for 

State oil- and gas-related activities. The moderate impacts from State oil and gas activities include 

a large oil spill (≥1,000 bbl). Impact levels for collision of trans-Gulf migrants with platforms, and 

possibly nocturnal circulation of trans-Gulf migrants, need further study. Impacts are expected to be 

minor. A large tanker spill (≥1,000 bbl) would have the same impact (moderate) as a similar sized 

OCS oil- and gas-related spill or State oil- and gas-related spill discussed above. Impacts to birds 

would be expected to be moderate. 

A source of cumulative impacts is obstruction lighting on platforms in State waters or on the 

OCS; obstruction lighting is under the jurisdiction of the USCG and is not likely to be changed by 

mitigations to protect birds. The impact level of obstruction lighting would need further study.

In addition to the OCS oil- and gas-related discharges discussed above, other regulated 

discharges include the discharge of bilge or ballast water from ships, runoff to waters, and industrial 

discharges into the coastal atmosphere, all of which are regulated by the USEPA. Also, agricultural 

nutrient (fertilizer) and pesticide runoff occurs. For more information and impact levels for runoff, 

other discharges into waters, and discharges into the atmosphere, refer to Chapter 4.1 (Air Quality) 

and Chapter 4.2 (Water Quality). Pollutants are expected to be diluted to a level below that which is 

harmful to birds or otherwise safely disposed of, and effects are not expected at a population level.
4-216 Gulf of Mexico Multisale EIS

Discard of trash and debris from non-OCS oil- and gas-related sources (e.g., from State oiland gas-related activities, recreational fishing boats, and land-based sources; refer to Chapter 

3.3.2.3.7) is prohibited; however, despite regulation, unknown quantities of plastics and other 

materials are discarded and lost in the marine environment and remain a threat to individual birds. 

Many species readily consume plastic debris, either intentionally or incidental to consuming prey, 

and can become trapped or entangled in discarded fishing line or nets. Although the short-term 

prognosis suggests that plastic impacts are increasing significantly, analyses also suggest that 

reductions in exposure would result in reduced ingestion (Wilcox et al., 2015). Seabirds are 

sometimes caught in commercial fishermen’s gear. Seabird bycatch numbers in the GOM (Hale et 

al., 2009) indicated that the pelagic and bottom longline fisheries had negligible impacts on 

seabirds. Discarded bycatch of fishes and invertebrates would benefit seabirds. Impacts to birds 

from trash and debris as a whole are expected to be moderate in the short term but negligible with 

forecasted reductions in exposure (Wilcox et al., 2015).

The Mississippi River watershed contributes nutrients causing a seasonal population 

explosion of phytoplankton, which decomposes to create a hypoxic or anoxic “dead zone” over the 

continental shelf (Chapter 3.3.2.12). Aquatic food for coastal waterbirds could be decimated in 

places in the hypoxic zone. However, the zone has been occurring since prehistoric times, and only 

its magnitude has recently changed (by application of agricultural fertilizer). No massive 

phytoplankton blooms have been reported to produce massive mortality to seabirds and other 

waterbirds in the zone. It is possible that birds are able to move from impacted areas with no food to 

patches of sufficient food; doing so would make the effects short term. All birds likely need to search 

for food sometimes. Impacts on a whole population are expected to be minor. 

Historical wetland loss due to Mississippi River hydromodification (Chapter 3.3.2.10) would 

be at least somewhat ameliorated by wetland creation form Atchafalaya River sediments and coastal 

restoration and hurricane protection programs. Also Louisiana’s Master Plan, which was partly 

designed for maximizing coastal wetlands, would likely increase habitat for four selected waterbird 

species and for neotropical birds over the next 50 years (refer to Chapter 4.3, Coastal Habitats). 

These predictions are based on Habitat Suitability Index models and were controlled for other, nonhabitat environmental variables (Nyman et al., 2013). Therefore, wetland loss would probably not be 

an issue that would exacerbate other impacts of a proposed action and other cumulative impacts for 

coastal and marine birds. For these reasons, impacts on whole populations are expected to be 

negligible. 

Military activities, including training overflights and sonic booms, would occur in special areas 

offshore in seabird habitat. Military operations in the Gulf of Mexico are undertaken primarily by the 

U.S. Air Force and the U.S. Navy within federally designated areas for the purposes of training 

personnel, as well as research, design, testing, and evaluation activities. There are 18 U.S. military 

bases along the northern Gulf of Mexico. The greatest impacts would come from sonic booms, 

which would likely cause an acute behavioral change such as flushing of a flock resting on the water 

or cessation of feeding by a flock. No individual or group of individuals would be injured or killed. 

Impacts would be expected to be negligible. 
Description of the Affected Environment and Impact Analysis 4-217

Nonconsumptive recreation includes bird-watching activities, all-terrain vehicle use, walking 

and jogging with pets, other beach use, and recreational boating. For economic impacts, refer to 

Chapter 4.12 (Recreational Resources). In most cases, recreational boats are subject to strict 

speed and wake restrictions. Disturbances of an area could be regular but impacts would be benign 

and direct (limited to the time period of disturbance); therefore, they would be minor. 

Consumptive recreation (hunting game birds) is carefully controlled by hunting regulations. 

Usually, total mortality of hunted species does not increase because of hunting—it remains the same 

because the overall carrying capacity of a species does not change with hunting. However, some 

species of game birds have experienced hunting-related mortality impacts at the population level, a 

major impact that would be mitigated to a net negligible impact by adjustments in hunting 

regulations.

Use of navigable waters by boats may cause erosion of banks by vessel wake, possibly 

causing wetland habitat loss. However, boat wakes are regulated by controlling vessel speed, so 

impacts on wetlands would be minimal. Because wetland habitat loss would be negligible, the 

potential impacts on birds would be negligible also.

There are a myriad of anthropogenic avian mortality sources, including collisions and 

predation by domestic cats. No GOM regional estimates are available for annual mortality rates for 

these sources. However, recent quantitative national estimates allow for a qualitative extrapolation 

to the GOM. An estimated range of national annual mortality from collision with vehicles is 

62-275 million birds per year (Loss et al., 2014a). An estimate of national annual mortality from 

collision with buildings is 599 million birds per year (Loss et al., 2014b). Finally, an estimate of 

annual mortality from predation by free-ranging domestic cats is 1.4-3.7 billion birds per year (Loss 

et al., 2013). The mortality estimates are nationwide and not just for the northern GOM, where 

impacts would be much less. Impacts of collisions with vehicles and buildings and predation by 

domestic cats are expected to be moderate (chronic but not causing steady declines in whole large 

populations).

Emerging infectious diseases include West Nile virus. LaDeau et al. (2007) stated that 

“Emerging infectious diseases present a formidable challenge to the conservation of native species 

in the twenty-first century.” The population responses of bird species to the virus was complex 

(LaDeau et al., 2007). Of 20 selected avian species across North America that were potential hosts 

to the West Nile virus, 7 species (35%) exhibited negative changes at the population level that were 

attributed to the virus, and only 2 of the 7 recovered to pre-West Nile virus levels by 2005 based on 

26 years of data (LaDeau et al., 2007). These continental estimates were meant to be qualitatively 

extrapolated to other species and can also be qualitatively extrapolated to the smaller area of the 

northern Gulf of Mexico (like the collision mortality estimates above). Impacts of the West Nile virus 

are at the population level and are expected to be major. 

Impacts of climate change (from global warming; refer to the Five-Year Program EIS, 

USDOI, BOEM, 2016b) and ocean acidification could eventually be expected to decline because the 
4-218 Gulf of Mexico Multisale EIS

gas emissions are controlled by law. If not curtailed, climate change could result in a decline in 

biodiversity that is vital to the ecosystems that support all bird life (McDaniel and Borton, 2002). 

Sea-level rise, along with natural wetland subsidence, can cause a landward retreat of the shoreline 

and coastal wetlands as discussed in Chapter 4.3 (Coastal Habitats). A recent comprehensive 

meta-analysis was completed on the impacts of ocean acidification on sea taxa (Kroeker et al., 

2013). Some of the taxa are related to important prey for birds or are related to organisms that 

support ecosystems important to those birds. Of taxa related to organisms important to birds, some 

features of some of them are expected to be impacted negatively by ocean acidification, some 

positively impacted, and some not affected at all (Kroeker et al., 2013). Forecasted impact levels of 

climate change and ocean acidification from burning the hydrocarbons produced by a proposed 

action or other sources of greenhouse gases cannot be determined at this time. Overall impacts of 

anthropogenic climate change, combined with ocean acidification on the bird resource in the 

northern GOM and contiguous land area due to a reduction in biodiversity of supporting ecosystems, 

are expected to be as great as major; however, there is still need for research in this area of 

science. 

Cumulative incremental impacts to birds, when taking into consideration the potential 

impacts of the Deepwater Horizon explosion, oil spill, and response, non-OCS oil- and gas-related 

factors, and the minimization of OCS oil- and gas-related impacts through lease stipulations and 

regulations, would be expected to be negligible as a result of a proposed action. This is because 

birds are wide-ranging, and population-level impacts are not anticipated. However, cumulative 

impacts could have a major impact on a particular bird species with a low population level, 

dependent upon the level of impact and the number of individuals affected by it (e.g., if an impact to 

a federally listed red knot or piping plover were to result in substantial mortality, it would diminish the 

continued viability of the population, including the annual rates of recruitment or survival).

Incomplete or Unavailable Information

BOEM has identified incomplete or unavailable information related to impacts on birds 

resulting from OCS oil- and gas-related activities and non-OCS oil- and gas-related activities in the 

GOM. BOEM’s subject-matter experts have used the available scientifically credible evidence 

presented below and applied accepted scientific methodologies to integrate existing information and 

extrapolate potential outcomes in completing this analysis and formulating the conclusions 

presented here.

Analyses of routine activities, accidental events, and cumulative impacts drew upon the most 

current and best available research to assess the potential impacts on birds, including available 

information from the NRDA process as a result of the Deepwater Horizon explosion, oil spill, and 

response. This incomplete information may be relevant to the evaluation of adverse effects because 

it could identify changes in the baseline environmental conditions for bird populations from the 

Deepwater Horizon oil spill and response, exacerbating any impacts from a proposed action. Much 

of these data are being developed through the NRDA process, which may take years to complete. 

At present, the best available information does not provide a complete understanding of the effects 
Description of the Affected Environment and Impact Analysis 4-219

of the spilled oil or the recovery potential for the most impacted species. However, any additional 

(NRDA) information obtained from the Deepwater Horizon oil spill and response is unlikely to be so 

significant as to change the relative importance of OCS oil- and gas-related and non-OCS oil- and 

gas-related impacts to bird populations. Also, even after it is released, the impacts of the oil spill 

may be difficult or impossible to discern from other factors. It is not possible for BOEM to obtain all 

of this information and incorporate it into this analysis within the timeline contemplated by the NEPA 

analysis of this Multisale EIS regardless of the costs or resources needed. Although additional 

information may be relevant to the evaluation of impacts to birds, BOEM has determined that the 

incomplete information is not essential to a reasoned choice among alternatives because existing 

information could be used instead, and because that information is already conservative, new 

information is unlikely to show an increase in impacts.

Impacts to habitat could also be due to urbanization, or they could be rural. Habitat (e.g., 

wetland) loss, alteration, and fragmentation associated with building, factory, and road construction 

is kept from harming sensitive bird habitat by standard mitigating measures required by the COE and 

State wetland permitting regulations. A major policy goal (not yet fully reached) is “no net loss” of 

wetlands. Therefore, impacts to birds would be expected to be negligible. 

Because information on the impact of artificial light along the coast on birds has not been 

studied, BOEM used available information to fill the data gap. Existing information (Longcore and 

Rich, 2004) shows that outdoor lights at night can have both lethal impacts from collisions and 

sublethal impacts from a variety of mechanisms on birds. The impact level of obstruction lighting 

located on platforms would also need further study. The best available information was obtained 

from a study done by observers on platforms, from a model of energy reserves of migratory birds, 

and from several studies of the effect of light on birds. This scientific information presented in the 

“Routine Activities” section and under State oil and gas activities in the “Cumulative Impacts” section 

was used to conclude that platform lighting, in general, has minor impacts. 

4.8.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

This chapter summarizes the potential impacts of routine activities, accidental events, and 

cumulative impacts associated with Alternative A on birds. Under Alternative A, BOEM would hold a 

regionwide lease sale comprised of the WPA, CPA, and a portion of the EPA.

Birds overlap with the proposed action area throughout their various life history stages. 

Different species have different feeding behaviors for different habitats. Many migrate seasonally 

and seabirds sometimes come to shore only to breed.

For impacts from routine activities, the effects from discharges and wastes, air and water 

quality, and noise would be negligible to coastal and migratory birds. Impacts of barotrauma from 

seismic airguns and platform severance with explosives would be minor. Impacts on trans-Gulf 

migrants from platform presence and lighting are tentatively minor but need further study of both 

positive and negative effects to be precisely assessed.
4-220 Gulf of Mexico Multisale EIS

An accidental event that may be associated with a proposed action and that has the largest 

impact on coastal and migratory birds is a large oil spill (≥1,000 bbl). Seabirds (compared with other 

bird groups) may not always experience the greatest impacts from a spill but may take longer to 

recover because of their unique population ecology (demography).

State oil- and gas-related activities would have the same impact-producing factors and 

expected impact levels as OCS oil- and gas-related activities. Discarding trash and debris would be 

a negligible impact. The hypoxic “dead zone” of the Mississippi River would have a minor impact. 

Net impacts of historic wetland loss and coastal wetland creation would be negligible. A large tanker 

spill (≥1,000 bbl) would have moderate impacts. Military activities would have minor impacts. 

Nonconsumptive recreation would have minor impacts. Consumptive recreation with any hunting 

regulation mitigation would have negligible impacts. Boat traffic would have a negligible impact on 

wetland bird habitat. Impacts of collisions with vehicles and buildings as well as predation by 

domestic cats would be moderate. Impacts of the West Nile virus and future emerging infectious 

diseases are at the population level. Partly because of this, the impacts, including the incremental 

contribution of a proposed lease sale, are expected to be major. Impacts of commercial fishing are 

expected to be positive for discarded fish and invertebrate bycatch and negligible for seabird 

bycatch. Impacts of climate change and ocean acidification cannot be determined at this time. 

Finally, impacts of wetland subsidence are expected to be moderate. The overall impacts from a 

proposed action on coastal and migratory birds are moderate. The incremental cumulative impacts 

of a proposed action to OCS oil- and gas-related anthropogenic events are considered moderate, 

but only because of the impacts of a large oil spill (≥1,000 bbl). However, the combined probabilities 

of a large oil spill for occurrence and contact with shoreline birds and nearshore waterbirds are 

small. The incremental cumulative impacts of a proposed action to non-OCS oil- and gas-related 

anthropogenic events and natural processes are considered major, but only because of the impact 

of non-native infectious diseases.

While the WPA is a smaller area with less projected activity than is proposed for the 

CPA/EPA (refer to Chapter 3), offshore pelagic seabird habitat is distributed throughout the planning 

areas. Therefore, activities isolated to specific planning areas pose similar potential impacts to 

offshore pelagic seabird populations as do activities occurring in all planning areas. Therefore, 

because of the diversity and distribution of offshore pelagic seabird species in the Area of Interest, 

the level of impacts would be the same for Alternatives A, B, C, and D. From a bird perspective, 

since Alternative A is regionwide, which includes the WPA, CPA, and EPA portions of the proposed 

lease sale area, it would have more of all of the types of OCS oil- and gas-related activities; 

therefore, it would have more potential for impacts. Impacts from the other alternatives would follow 

in a graded fashion. For platforms, the number of spills between 1,000 and 10,000 bbl has been 

estimated to be <1 for Alternatives A, B, and C (i.e., spill); also for platforms, the number of spills 

≥10,000 bbl has also been estimated to be <1 for Alternatives A, B, and C. For pipelines, the 

number of spills between 1,000 and 9,999 bbl has been estimated to be <1 to 1 for Alternative A; 

also for pipelines, the number of spills ≥10,000 bbl has been estimated to be <1 for Alternative A.
Description of the Affected Environment and Impact Analysis 4-221

4.8.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM would hold a lease sale excluding the WPA available lease sale 

blocks and offer all available blocks in the CPA and a portion of the EPA. The impacts to birds from 

Alternative B are similar to those from Alternative A since a majority of the activity is projected to 

occur in the CPA, as described in Chapter 3.1, and since overall routine and accidental impacts are 

considered moderate, but only because of the impacts of a large oil spill (≥1,000 bbl). The 

combined probabilities for occurrence and contact with shoreline birds and nearshore waterbirds are 

small. The incremental cumulative impacts of Alternative B to OCS oil- and gas-related impacts are 

considered moderate, but only because of the impacts of a large oil spill (≥1,000 bbl). Trans-Gulf 

migrant birds stopping over on platforms and drilling vessels mostly follow a fall southward migratory 

route that, under East Continental High synoptic wind conditions, crosses mostly outside the western 

Gulf (refer to Figure 4-20). Migrant birds stop over on GOM offshore structures in fall, collide with 

the structures, and exhibit nocturnal circulation just like in the spring (Russell, 2005), even though 

they are just beginning their nonstop flight in the fall. During Bermuda High wind conditions, birds 

mostly do not migrate in the fall (Russell, 2005). Drilling vessels and new platforms under 

Alternative B would be entirely outside the western Gulf; therefore, both positive and negative 

impacts from offshore structures on trans-Gulf migrants migrating during an East Continental High 

would be less than under Alternative C. Juvenile trans-Gulf southward fall migration often differs 

from adult migration in that it often hugs the Texas coast. It is possible that juveniles lack the 

reserves for nonstop overwater flight. In any case, they would possibly stop over on platforms on 

the OCS near the Texas coast, and the leasing area under Alternative C (i.e., the WPA) is off the 

Texas coast. The leasing area for Alternative B is the CPA/EPA. Therefore, both positive and 

negative impacts on juveniles would occur under Alternative C but not under Alternative B. The 

incremental cumulative impacts of Alternative B to non-OCS oil-and gas-related anthropogenic 

events and natural processes are considered major, but only because of the anthropogenic impact 

of non-native infectious diseases. The significance of impact-producing factors on birds would be 

the same for Alternative B as for Alternative A. The degree of impacts as a result of Alternative B 

would be somewhat less than Alternative A since a majority of the routine activities and impactproducing factors from a proposed lease sale would occur in the CPA/EPA, as projected in the 

scenario in Chapter 3.1.1. For platforms, the number of spills between 1,000 and 9,999 bbl has 

been estimated to be <1 for Alternative B; also for platforms, the number of spills ≥10,000 bbl has 

also been estimated to be <1 for Alternative B. For pipelines, the number of spills between 

1,000 and 9,999 bbl has been estimated to be <1 for Alternative B.

4.8.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Under Alternative C, BOEM would hold a lease sale excluding the CPA/EPA available lease 

blocks and offer all available blocks in the WPA. The impacts to birds from OCS oil-and gas-related 

activities are similar in the WPA or wherever they may occur in the GOM, and overall routine and 

accidental impacts from Alternative C are considered moderate, but only because of the impacts of 

a large oil spill (≥1,000 bbl). Trans-Gulf migrant birds stopping over on platforms and drilling vessels 
4-222 Gulf of Mexico Multisale EIS

mostly follow a spring northward migratory route that, under East Continental High synoptic wind 

conditions, crosses mostly the western Gulf (refer to Figure 4-20). Drilling vessels and new 

platforms under Alternative C would be entirely in the WPA; therefore, both positive and negative 

impacts from offshore structures on trans-Gulf migrants migrating during an Eastern Continental 

High would be greater than under Alternative C than under Alternative B. However, under Bermuda 

High synoptic wind conditions, migration would no longer be mostly just across the western Gulf 

(refer to Figure 4-21); therefore, the favorable reduced impacts to trans-Gulf migrants extant under 

Alternative C under East Continental High conditions in spring would not occur. Juvenile trans-Gulf 

southward fall migration often differs from adult migration in that it often hugs the Texas coast. It is 

possible that juveniles lack the reserves for nonstop overwater flight. In any case, they would 

possibly stop over on platforms on the OCS near the Texas coast, and the leasing area under 

Alternative C (i.e., the WPA) is off the Texas coast. The leasing area for Alternative B is the 

CPA/EPA; therefore, both positive and negative impacts on juveniles would occur under Alternative 

C but not under Alternative B. For platforms, the number of spills between 1,000 and 9,999 bbl has 

been estimated to be <1 for Alternatives C; also for platforms, the number of spills ≥10,000 bbl has 

also been estimated to be <1 for Alternative C.

Alternative C would have the same potential for impact as Alternative A or B since the level 

of projected OCS oil- and gas-related activities and impact-producing factors are less in the WPA but 

are still substantial. For example, a range of 11-67 production wells are projected to be drilled and 

developed under Alternative C, whereas 58-464 production wells are projected to occur under 

Alternative B. The incremental cumulative impacts of Alternative C to OCS oil- and gas-related 

anthropogenic events are considered moderate, but only because of the impacts of a large oil spill 

(≥1,000 bbl). However, the incremental cumulative impacts of Alternative C to OCS oil- and gasrelated anthropogenic events are considered moderate, but only because of the impacts of a large 

oil spill (≥1,000 bbl). The significance of impact-producing factors on birds would be somewhat the 

same for Alternative C as for Alternative A. Alternative C would have a somewhat less impact than 

Alternatives A and B since the geographical planning area is smaller and less activity is projected to 

occur in the WPA under the scenario in Chapter 3.1.1. 

4.8.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, the impacts to birds are similar wherever they may occur in the GOM, 

and overall routine and accidental impacts are considered moderate, but only because of the 

impacts of a large oil spill (≥1,000 bbl). The incremental cumulative impacts of Alternative D to OCS 

oil- and gas-related anthropogenic events are considered moderate, but only because of the 

impacts of a large oil spill (≥1,000 bbl). Also, the incremental impacts of Alternative D on other nonOCS oil-and gas-related anthropogenic events and natural processes are considered major, but 

only because of the anthropogenic impact of non-native infectious diseases. The significance of 

impact-producing factors on birds could be somewhat less for Alternative D than for Alternative A, B, 

or C since a few blocks and associated activities would be removed from the proposed lease sale 
Description of the Affected Environment and Impact Analysis 4-223

area. However, since there are so few unleased blocks subject to the Topographic Features, Live 

Bottom, and Blocks South of Baldwin County, Alabama, Stipulations, this would be a small 

incremental change compared with the other action alternatives. The impacts under Alternative D 

would not be much different and likely not even measurable when compared with the other action 

alternatives.

4.8.2.5 Alternative E—No Action

Alternative E would result in no impacts from a proposed lease sale; there would only be 

impacts associated with the continuing impacts from past lease sales, at least in the short term. 

Alternative E would offer no new lease blocks for exploration and development; therefore, no 

impacts from a proposed lease sale would occur. Existing oil and gas activities from previously 

permitted activities, previous lease sales, and associated impacts would continue.

4.9 PROTECTED SPECIES

The Endangered Species Act of 1973 (ESA), as amended, establishes a national policy 

designed to protect and conserve threatened and endangered species and the ecosystems upon 

which they depend. In fulfilling these requirements, each agency must use the best scientific and 

commercial data available. The FWS and NMFS share responsibility for implementing the ESA.

The Marine Mammal Protection Act of 1972 (MMPA) prohibits, with certain exceptions, the 

"take" of marine mammals in U.S. waters and by U.S. citizens on the high seas and the importation 

of marine mammals and marine mammal products into the U.S. The NMFS and FWS are also 

responsible for the MMPA.

For the GOM, the NMFS is charged with protecting all cetaceans while manatees are under 

the jurisdiction of the FWS. Details on BOEM’s consultations and coordination are presented in 

Chapter 5.7 (Endangered Species Act).

Protected species for the purposes of this Multisale EIS include ESA- and MMPA-listed 

species and associated designated critical habitat under the ESA. The species considered in this 

chapter, pursuant to our consultations and coordination, and within Table 4-12 are those that could 

be affected within the GOM Area of Interest and that are subject to the proposed activities under the 

alternatives. For those species not considered further because they are unlikely to be affected by 

the proposed activities, refer to Appendix F. Critical habitats noted within the GOM Area of Interest 

are shown in Figure 4-23 and are mentioned in this chapter, but comprehensive details on many of 

these habitats can be found in Chapters 4.3 (Coastal Habitats), 4.5 (Sargassum and Associated 

Communities), and 4.6 (Live Bottom Habitats).
4-224 Gulf of Mexico Multisale EIS

Table 4-12. Species within the Gulf of Mexico That Are Protected Under the Endangered Species Act 

and/or the Marine Mammal Protection Act.

Common Name Scientific Name Common Name Scientific Name

Marine Mammals Sea Turtles

Atlantic spotted 

dolphin* Stenella frontalis* Green sea turtle2 Chelonia mydas2

Blainville’s beaked 

whale*

Mesoplodon 

densirostris* Hawksbill sea turtle3 Eretmochelys imbricata3

Bottlenose dolphin* Tursiops truncatus* Kemp’s ridley sea 

turtle3 Lepidochelys kempii3

Bryde’s whale* Balaenoptera edeni*

Northwest Atlantic 

Ocean loggerhead sea 

turtle4

Caretta caretta4

Clymene dolphin* Stenella clymene* Leatherback sea turtle 

(Atlantic Northwest)3

Dermochelys 

coriacea3

Cuvier’s beaked 

whale* Ziphius cavirostris* Beach Mice

Dwarf sperm whale* Kogia sima* Alabama beach 

mouse3

Peromyscus 

polionotus 

ammobates3

False killer whale* Pseudorca 

crassidens*

Choctawhatchee beach 

mouse3

Peromyscus 

polionotus allophrys3

Fraser’s dolphin* Lagenodelphis hosei* Perdido Key beach 

mouse3

Peromyscus 

polionotus 

trissyllepsis3

Gervais’ beaked 

whale*

Mesoplodon 

europaeus*

St. Andrew beach 

mouse3

Peromyscus 

polionotus 

peninsularis3

Killer whale* Orcinus orca* Birds

Melon-headed whale* Peponocephala 

electra*

Cape Sable seaside 

sparrow3

Ammodramus 

maritimus mirabilis3

Pantropical spotted 

dolphin* Stenella attenuate* Mississippi sandhill crane3

Grus canadensis 

pulla3

Pygmy killer whale* Feresa attenuata* Piping plover4 Charadrius melodus4

Pygmy sperm whale* Kogia breviceps* Red knot4 Calidris canutus rufa4

Risso’s dolphin* Grampus griseus* Roseate tern4 Sterna dougallii 

dougallii4

Rough-toothed 

dolphin* Steno bredanensis* Whooping crane3 Grus americana3

Short-finned pilot 

whale*

Globicephala 

macrorhynchus* Wood stork4 Mycteria americana4

Sperm whale1 Physeter 

macrocephalus1 Corals

Spinner dolphin* Stenella longirostris* Elkhorn coral4 Acropora palmata4

Striped dolphin* Stenella 

coeruleoalba* Staghorn coral4 Acropora cervicornis4

West Indian manatee1 Trichechus manatus1 Boulder star coral4 Orbicella franksi4

Lobed star coral4 Orbicella annularis4

Mountainous star coral4 Orbicella faveolata4
Description of the Affected Environment and Impact Analysis 4-225

* This species is protected under the Marine Mammal Protection Act (MMPA).

1 This species is listed under the Endangered Species Act (ESA) as “endangered” and 

is also protected under the MMPA.

2 This species is listed under the ESA as “threatened,” except for breeding populations 

of Florida which are “endangered.”

3 This species is listed under the ESA as “endangered.”

4 This species is listed under the ESA as “threatened.”

Impact-Level Definitions

As the routine activities, accidental events, and cumulative impacts are considered for 

specific listed species, each is given criteria per level of impact represented below.

Negligible – An individual or group of animals would be subject to nominal to 

nominal to slight measurable impacts. No mortality or injury to any individual 

would occur, and no disruption of behavioral patterns would be expected. The 

disturbance would last only as long as the human-caused stimulus was 

perceptible to the individual or group.

Minor – An individual or group of animals would be subject to a human-caused 

stimulus and be disturbed, resulting in an acute behavioral change. No mortality 

or injury to an individual or group would occur.

Moderate – An individual or group of animals would be subject to a human-caused 

stimulus and be disturbed, resulting in a chronic behavioral change. Individuals 

may be impacted but at levels that do not affect the fitness of the population. 

Some impacts to individual animals may be irreversible.

Major – An individual or group of animals would be subject to a human-caused 

stimulus, resulting in physical injury or mortality, and would include sufficient 

numbers that the continued viability of the population is diminished, including 

annual rates of recruitment or survival. Impacts would also include permanent 

disruption of behavioral patterns that would affect a species or stock.

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

with a GOM proposed action and a proposed action’s incremental contribution to the cumulative 

impacts are presented in detail within the chapters below. The approach of the analysis is to focus 

on the potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., 

exploration, development, and production), as well as accidental events and cumulative impacts, 

and to define impact-level measures for each impact-producing factor for protected species, as 

summarized in Table 4-13. These impacts are across all action alternatives (A, B, C, and D) except 

for beach mice and protected corals. Beach mice are not found in the WPA; therefore, they are not 

relevant for Alternative B, and the ranges given for potential impacts to protected corals are based 

on whether or not stipulations are placed on leases.
4-226 Gulf of Mexico Multisale EIS

Figure 4-23. Gulf of Mexico Protected Species’ Critical Habitats.
Description of the Affected Environment and Impact Analysis 4-227

Table 4-13. Protected Species Impact-Producing Factors.

Protected Species Magnitude of Potential Impact

Impact-Producing 

Factors

Marine 

Mammals Sea Turtles Beach Mice1

Protected 

Birds

Protected 

Corals2 

Routine Impacts

Geological and 

Geophysical Activities

Negligible to Negligible to N/A N/A N/A

Moderate Moderate

Transportation

(vessel strikes)

Negligible to Negligible to N/A N/A N/A

Major Moderate

Discharges

(air and water quality 

degradation)

Negligible Negligible N/A Negligible Moderate

Marine Trash and 

Debris

Negligible to Moderate Negligible Negligible to N/A

Major Moderate

Decommissioning 

(explosive severance)

Negligible to Negligible to N/A Minor N/A

Moderate Moderate

Noise Negligible to Negligible N/A Negligible N/A

Minor

Drilling and Exploration 

(bottom-disturbing 

activities)

N/A N/A N/A N/A

Negligible to

Minor

Offshore 

Lighting/Platform 

Presence

N/A N/A N/A

Negligible to

N/A

Moderate

Vessel Operation 

(bottom-disturbing 

activities)

N/A N/A N/A N/A

Negligible to

Minor

Accidental Impacts

Oil Spills Negligible to Negligible to Negligible Negligible to Negligible to

Major Moderate Moderate Moderate

Oil-Spill Response 

Activities

Negligible to Negligible to Negligible Negligible to Negligible to

Moderate Moderate Moderate Moderate

Cumulative Impacts

All OCS Activities Negligible to Negligible to Negligible Negligible to Negligible to

Major Moderate Moderate Minor

All Non-OCS Activities Negligible to Negligible to Negligible to Negligible to Negligible to

Major Major Major Major Moderate

1 Beach mice are not found in the WPA; therefore, they are not likely to be impacted by Alternative B.

2 Ranges for the potential impacts to protected corals are based on whether or not protected 

stipulations are placed on leases.

N/A represents those impact-producing factors that are not applicable to that protected species group.
4-228 Gulf of Mexico Multisale EIS

For protected coral impact-producing factors, refer to Table 4-8 in Chapter 4.6.1

(Topographic Features) since coral impact-producing factors are covered in detail there and would 

apply to protected corals as well. For protected birds impact-producing factors, refer to Table 4-12

in Chapter 4.8 (Birds) since the impact-producing factors that impact coastal, marine, and migratory 

birds (the listed birds are either found in coastal areas or are migratory and utilize coastal areas as 

part of their life history) are covered in detail there. For beach mice, the most relevant impactproducing factors are those causing harm to the populations by affecting their habitat (beaches). 

Table 4-5 in Chapter 4.3.2 (Coastal Barrier Beaches and Associated Dunes) covers the impactproducing factors that affect beaches and dunes, and details about those impacts to beach mouse 

habitat can be found there. The specific impact-producing factors that are covered in Table 4-13

above and that would affect the biology of beach mice are marine debris (negligible), oil spills 

(negligible), and cumulative (negligible). For more details on the biological effects to beach mice, 

refer to Chapter 4.9.3 (Beach Mice).

4.9.1 Marine Mammals

The Gulf of Mexico marine mammal community is diverse and distributed throughout the 

GOM, including northern U.S. waters. The GOM’s Cetacea include the suborders Mysticeti (i.e., 

baleen whales) and Odontoceti (i.e., toothed whales), and the order Sirenia, which includes the West 

Indian manatee. Most marine mammal distributions vary widely across the northern GOM with very 

little known about their respective breeding and calving grounds, as well as any potential migratory 

routes. While all marine mammals are protected under the MMPA, two species (i.e., the sperm 

whale and West Indian manatee) are listed as endangered under the ESA due to various factors, 

which are described in this chapter. The analyses of the potential impacts of routine activities and 

accidental events associated with a proposed lease sale and a proposed lease sale’s incremental 

contribution to the cumulative impacts to marine mammals are presented in this chapter. Potential 

impact-level criteria are defined in Chapter 4.9 (Protected Species) and apply to marine mammal 

species described in this chapter. The approach of the analysis is to focus on the potential impactproducing factors from OCS oil- and gas-related routine activities (i.e., exploration, development, 

and production), as well as accidental events and cumulative impacts, and to define impact-level 

measures for each impact-producing factor in relation to the best available population estimates 

(refer to Table 4-13 in Chapter 4.9). Some impact-producing factors may have different potential 

impact levels to different marine mammal species due to their various population sizes, as well as 

their wide-ranging behavior; thus, some potential impact-producing factors are described in a range.

4.9.1.1 Description of the Affected Environment

Twenty-one species of cetaceans and one species of sirenian (West Indian manatee) 

regularly occur in the GOM and are identified in the NMFS’s Gulf of Mexico Stock Assessment 

Reports (Jefferson et al., 1992; Davis et al., 2000; Waring et al., 2014). Along with stock estimates, 

the NMFS also calculates the Potential Biological Removal (PBR), which is defined under the MMPA 

as the maximum number of animals, not including natural mortalities, that may be removed from a 

marine mammal stock while allowing that stock to reach or maintain its optimum sustainable 

population (USDOC, NMFS, 2007b). The PBR level is the product of the minimum population 
Description of the Affected Environment and Impact Analysis 4-229

estimate of the stock, one-half the maximum theoretical or estimated net productivity rate of the 

stock at a small population size, and a recovery factor of between 0.1 and 1.0 (USDOC, NMFS, 

2007b). The PBR plays an important role in marine mammal management due to the fact that the 

same potential impact-producing factor may have a more serious impact on a marine mammal stock 

that has a lower PBR and a less serious impact to a marine mammal stock with a higher PBR.

There are species that have been reported from GOM waters either by sighting or stranding 

that, due to their rarity, are not considered in this Multisale EIS (Wursig et al., 2000; Mullin and 

Fulling, 2004). These species include the following: the blue whale (Balaenoptera musculus), North 

Atlantic right whale (Eubalaena glacialis), and Sowerby’s beaked whale (Mesoplodon bidens), all of 

which are considered extralimital in the Gulf of Mexico; and the humpback whale (Megaptera 

novaeangliae), fin whale (Balaenoptera physalus), sei whale (Balaenoptera borealis), and minke 

whale (Balaenoptera acutorostrata), all of which are considered rare occasional migrants in the Gulf 

of Mexico (Wursig et al., 2000; Mullin and Fulling, 2004). Because these species are uncommon in 

the GOM and because they are not included in the most recent NMFS Gulf of Mexico Stock 

Assessment Reports, BOEM did not consider them for this analysis as they are unlikely to be 

impacted by OCS oil- and gas-related activities. Population estimates for marine mammals in the 

GOM are represented in Table 4-14. The most recent abundance estimates available for all 

cetacean species mentioned in this Multisale EIS can be found on NMFS’s website (USDOC, NMFS, 

2015b), and estimates for manatees can be found on the Florida Fish and Wildlife Conservation 

Commission’s website (State of Florida, Fish and Wildlife Conservation Commission, 2015).

Table 4-14. Best Available Population Estimates for Marine Mammal Species in the Northern Gulf of 

Mexico.

Species Population Estimate PBR*

Bryde’s Whale (Balaenoptera brydes) 33 0.1

Sperm Whale (Physeter macrocephalus) 763 1.1

Pygmy Sperm Whale (Kogia breviceps) 186a 0.9

Dwarf Sperm Whale (Kogia sima) 186a 0.9

Gervais’ Beaked Whale (Mesoplodon europaeus) 149b 0.8

Blainville’s Beaked Whale (Mesoplodon densirostris) 149b 0.8

Cuvier’s Beaked Whale (Ziphius cavirostris) 74 0.4

Bottlenose Dolphin (Tursiops truncatus) 

Oceanic waters

Northern Coastal Stock

Eastern Coastal Stock

Western Coastal Stock

Continental Shelf Stock

Bay, Sound, and Estuary (27 stocks)

Barataria Bay Estuarine System

Mississippi Sound, Lake Borgne, and Bay 

Boudreau

5,806

7,185

12,388

20,161

51,192

Unknown 

for all but 4 stocks 

Unknown

901

42

60

111

175

469

Undetermined 

for all but 4 stocks

Undetermined

5.6
4-230 Gulf of Mexico Multisale EIS

Species Population Estimate PBR*

Clymene Dolphin (Stenella clymene) 129 0.6

Pantropical Spotted Dolphin (Stenella attenuata) 50,880 407

Atlantic Spotted Dolphin (Stenella frontalis) Unknown Undetermined

Risso’s Dolphin (Grampus griseus) 2,442 16

Rough-toothed Dolphin (Steno bredanensis) 624 3

Spinner Dolphin (Stenella longirostris) 11,441 62

Striped Dolphin (Stenella coeruleoalba) 1,849 10

False Killer Whale (Pseudorca crassidens) Unknown Undetermined

Fraser’s Dolphin (Lagenodelphis hosei) Unknown Undetermined

Killer Whale (Orcinus orca) 28 0.1

Melon-headed Whale (Peponocephala electra) 2,235 13

Pygmy Killer Whale (Feresa attenuata) 152 0.8

Short-finned Pilot Whale (Globicephala 

macrorhynchus)

c 2,415 15

West Indian Manatee 6,063 Undetermined

a This estimate includes both the dwarf and pygmy sperm whales.

b This estimate includes Gervais’ beaked whales and Blainville’s beaked whales in 

the GOM. c This estimate includes all Globicephala sp., though it is presumed that only 

short-finned pilot whales are present in the Gulf of Mexico.

* Potential Biological Removal (PBR) estimates from Waring et al., 2014.

Sources: State of Florida, Fish and Wildlife Conservation Commission, 2015.

Waring et al., 2014.

Threatened or Endangered Species

The sperm whale (Physeter macrocephalus) and the West Indian manatee (Trichechus 

manatus) are the only ESA-listed marine mammals that regularly occur in the GOM. The sperm 

whale is common in oceanic waters of the northern GOM and appears to be a resident species 

(Mullin et al., 1991; Davis and Fargion, 1996; Jefferson and Schiro, 1997). The West Indian 

manatee is commonly found along the coast of Florida in the winter and may migrate as far as Texas 

in the warmer seasons, typically inhabiting only shallow coastal marine, brackish, and freshwater 

areas. The FWS provided notice of the petition on January 8, 2016, to reclassify the West Indian 

manatee from endangered to threatened (Federal Register, 2016b). If this petition becomes a final 

rule and the West Indian manatee meets the requirements to be reclassified as threatened, it would 

still have protection under the ESA because it would still be an ESA-listed species.

Cetaceans—Odontocetes

The sperm whale was listed as endangered in 1970 (Federal Register, 1970). It is found 

worldwide in deep waters between approximately 60°N. and 60°S. latitude (Whitehead, 2002), 

although generally only large males venture to the extreme northern and southern portions of their 

range (Jefferson et al., 1993). Females and juveniles form pods that are found mainly at tropical and 
Description of the Affected Environment and Impact Analysis 4-231

temperate latitudes (between 50°N. and 50°S. latitude), while the solitary adult males can be found 

at higher latitudes (between 75°N. and 75°S. latitude) (Reeves and Whitehead, 1997). In the 

western North Atlantic, they range from Greenland to the Gulf of Mexico and the Caribbean Sea. As 

deep divers, sperm whales generally inhabit oceanic waters at depths greater than 591 ft (180 m), 

but they do come close to shore where submarine canyons or other geophysical features bring deep 

water near the coast (Jefferson et al., 1993). Sperm whales prey on cephalopods, demersal fishes, 

and benthic invertebrates (Rice, 1989; Jefferson et al., 1993).

The NMFS considers sperm whales in the GOM as a distinct stock in the Marine Mammal 

Stock Assessment Report (Waring et al., 2014), and research supports this distinction from the 

Atlantic and Caribbean stocks (Engelhaupt et al., 2009; Gero et al., 2007; Jaquet, 2006; Jochens 

et al., 2008). Consistent sightings, satellite tracking, strandings, whale catching, and recent 

research indicate that sperm whales occupy the northern GOM throughout all seasons and that 

aggregations are commonly found in waters over the shelf edge in the vicinity of the Mississippi 

River Delta, which are 1,641-6,562 ft (500-2,000 m) in depth, and represent a resident population 

(Mullin et al., 1994a; Davis and Fargion, 1996; Sparks et al., 1996; Jefferson and Schiro, 1997; 

Davis et al., 2000; Jochens et al., 2008). Seasonal aerial surveys confirmed that sperm whales 

sightings are more common during summer (Mullin et al., 1991 and 1994a; Mullin and Hoggard, 

2000; Mullin and Fulling, 2004), but this may be an artifact of movement patterns of sperm whales 

associated with reproductive behavior, hydrographic features, or other environmental or seasonal 

factors. Because of the lack of adult males observed in the GOM, it is not known whether females 

leave the area to mate or whether males sporadically enter the area to mate with females, which 

would make this a very important area for sperm whale reproduction. Throughout this chapter, 

where information was incomplete or unavailable, BOEM complied with its obligations under NEPA 

to determine if the information was relevant to reasonably foreseeable significant adverse impacts; if 

so, whether it was essential to a reasoned choice among alternatives; and, if it was essential, 

whether it can be obtained and whether the cost of obtaining the information is exorbitant, as well as 

whether credible scientific information applied using generally accepted scientific methodologies can 

be used in its place (40 CFR § 1502.22). BOEM has made conscientious efforts to comply with the 

spirit and intent of NEPA and to be comprehensive in its analyses of potential environmental 

impacts. 

While they may be encountered almost anywhere on the high seas, their distribution shows a 

preference for continental margins, sea mounts, and areas of upwelling, where food is abundant 

(Leatherwood and Reeves, 1983). The low-salinity, nutrient-rich water from the Mississippi River 

contributes to enhanced primary and secondary productivity in the north-central GOM and may 

explain the presence of sperm whales in the area (Würsig et al., 2000; Davis et al., 2000 and 2002; 

Jochens et al., 2008). The continental margin in the north-central GOM is only 12 mi (20 km) wide at 

its narrowest point, and the ocean floor descends quickly along the continental slope, reaching a 

depth of 3,281 ft (1,000 m) within 25 mi (40 km) of the coast. This unique area of the GOM brings 

deepwater organisms within the influence of coastal fisheries, contaminants, and other human 

impacts on the entire northern GOM. Sperm whales are noted for their ability to make prolonged 

deep dives and are likely the deepest and longest diving mammal. Typical foraging dives last 
4-232 Gulf of Mexico Multisale EIS

approximately 40 minutes and descend to about 1,312 ft (400 m), followed by approximately 

8 minutes of resting at the surface (Papastavrou et al., 1989). However, dives of over 2 hours and 

deeper than 2.1 mi (3.3 km) have been recorded (Clarke, 1976; Watkins et al., 1985; Watkins et al., 

1993), and individuals may spend extended periods of time at the surface to recover.

Evidence suggests that the disproportionately large head of the sperm whale is an 

adaptation to produce vocalizations (Norris and Harvey, 1972; Cranford, 1992). This suggests that 

vocalizations are extremely important to sperm whales. The function of vocalizations is relatively 

well-studied (Weilgart and Whitehead, 1997; Goold and Jones, 1995). Long series of monotonous, 

regularly spaced clicks are associated with feeding and are thought to be produced for echolocation. 

Sperm whales also use unique stereotyped click sequence “codas” (Mullins et al., 1988; Watkins 

and Scheville, 1977; Watkins et al., 1985), according to Weilgart and Whitehead (1988), to possibly 

convey information about the age, sex, and reproductive status of the sender. Groups of closely 

related females and their offspring have group-specific dialects (Weilgart and Whitehead, 1997). 

Sperm whale vocalization and audition are important for echolocation and feeding, social behavior 

and intragroup interactions, and maintaining social cohesion within the group. Further detailed 

information on sperm whale hearing may be found in BOEM’s Atlantic OCS Proposed Geological 

and Geophysical Activities: Mid-Atlantic and South Atlantic Planning Areas, Final Programmatic 

Environmental Impact Statement, which can be found on BOEM’s website at http://www.boem.gov/

Atlantic-G-G-PEIS/#Final PEIS (USDOI, BOEM, 2014a).

The age distribution of the GOM sperm whale population is unknown, but they are believed 

to live at least 60 years. Potential sources of natural mortality in sperm whales include killer whales 

and a papilloma virus (Lambertsen et al., 1987). Little is known of recruitment and mortality rates; 

however, recent abundance estimates based on surveys indicate that the population appears to be 

stable, but the NMFS believes that there is insufficient data to determine population trends in the 

GOM for this species at this time (Waring et al., 2014).

Cephalopods (i.e., squid, octopi, cuttlefishes, and nautilus) are the main dietary component 

of sperm whales. Other sperm whale populations are known to also take significant quantities of 

large demersal and mesopelagic fishes, especially the mature males in higher latitudes (Clarke, 

1962 and 1979). Postulated feeding and hunting methods include lying suspended and relatively 

motionless near the ocean floor and ambushing prey, attracting squid and other prey to the white 

lining of their mouths by disturbing bioluminescent organisms around them to make their mouths 

more visible, or stunning prey with ultrasonic sounds (Norris and Mohl, 1983; Würsig et al., 2000). 

Evidence of ingested stones, sand, sponges, and other non-food items suggests they forage on or 

near the bottom (Rice, 1989) and may occasionally drown after becoming entangled in deep-sea 

cables that wrap around their lower jaw (Würsig et al., 2000).

The primary factor for the population decline was commercial whaling in the 18th, 19th, and 

20th centuries. A commercial fishery for sperm whales operated in the GOM during the late 1700’s 

to the early 1900’s, but the exact number of whales taken is not known (Townsend, 1935). The 

overharvest of sperm whales resulted in their alarming decline in the last century. The total take of 
Description of the Affected Environment and Impact Analysis 4-233

sperm whales worldwide between 1800 and 1909 has been estimated as close to 700,000 and 

between 1910 and 1973 as close to 605,000 (Best et al., 1984). Sperm whales have been protected 

from commercial harvest by the International Whaling Commission since 1981, although the 

Japanese continued to harvest sperm whales in the North Pacific until 1988 (Reeves and 

Whitehead, 1997). Since the ban on nearly all hunting of sperm whales, there has been little 

evidence that direct effects of anthropogenic causes of mortality or injury (e.g., vessel strikes, 

commercial fishing, entanglements, etc.) are significantly affecting the recovery of sperm whale 

stocks (Perry et al., 1999), yet the effects of these activities on the behavior of sperm whales has 

just recently begun to be studied. Sperm whales are also protected by the Convention on 

International Trade in Endangered Species of Wild Flora and Fauna and the Marine Mammal 

Protection Act of 1972. As of 2002, the global population of sperm whales is estimated to be at 

32 percent of its pre-whaling number (Whitehead, 2002).

Since sperm whales were listed under the ESA, a concern for the impacts of anthropogenic 

activities on the physiology and behavior of marine mammals has received much attention. The 

NMFS published a final recovery plan for the sperm whale (USDOC, NMFS, 2010b), and current 

threats to sperm whale populations worldwide are discussed. Threats are defined as “any factor that 

could represent an impediment to recovery” and include fisheries interactions, anthropogenic noise, 

vessel interactions, contaminants and pollutants, disease, injury from marine debris, research, 

predation and natural mortality, direct harvest, competition for resources, loss of prey base due to 

climate change and ecosystem change, and cable laying. In the GOM, the impacts from all of these 

threats are identified as either low or unknown (USDOC, NMFS, 2010b).

The commercial fishery, which potentially could interact with the GOM sperm whale stock, is 

the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico large pelagic longline fishery (Waring et al., 

2013). There have been no reports of mortality or serious injury to sperm whales by this fishery 

(Waring et al., 2013), although one sperm whale was released alive with no serious injury after an 

entanglement interaction with the pelagic longline fishery in 2008 (Garrison et al., 2009).

In regards to the impacts of anthropogenic noise, the Five-Year Review of the NMFS’s 

recovery plan recognizes that there is a concern, but additional research is needed to fully 

understand possible injury and behavior changes (USDOC, NMFS, 2015c). Anthropogenic sources 

from vessel noise, noise associated with oil production, seismic surveys, and other sources have the 

potential to impact sperm whales. Little is known about sperm whale reactions to seismic 

exploration, and available studies provide inconsistent results. Further discussion of seismic 

exploration and marine mammals can be found in the “Routine Activities” section below (Chapter 

4.9.1.2).

BOEM has completed the “Sperm Whale Seismic Study in the GOM,” and a synthesis report 

was published in 2008 (Jochens et al., 2008). The principle conclusions from this multiyear research 

effort were as follows:
4-234 Gulf of Mexico Multisale EIS

• the data support the conservation of sperm whales in the northern GOM as a 

discrete stock;

• sperm whales are present year-round in the GOM, with females generally having 

significant site fidelity and with males and females exhibiting significant 

differences in habitat usage;

• the sperm whale population off the Mississippi River Delta likely has a core size 

of about 140 individuals;

• GOM sperm whales seem to be smaller in individual size than sperm whales in 

some other oceans;

• some groups of sperm whales in the GOM were mixed-sex groups of 

females/immatures and others were groups of bachelor males and typical group 

size for mixed groups was 10 individuals, which is smaller than group sizes in 

some other oceans;

• the typical diving and underwater behaviors of the GOM’s sperm whales are 

similar to those of animals in other oceans;

• the typical feeding and foraging behaviors of the GOM’s sperm whales are 

similar to those of animals in other oceans, although differences in defecation 

rates suggest possible differences in feeding success;

• in the otherwise oligotrophic Gulf of Mexico, the eddy field contributes to the 

development of regions of locally high surface productivity that, in turn, may 

create conditions favorable for the trophic cascade of surface production to the 

depths where GOM sperm whales dive to forage;

• there appeared to be no horizontal avoidance to controlled exposure of seismic 

airgun sounds by sperm whales in the main “Sperm Whale Seismic Study” area;

• data analysis suggests it is more likely than not that some decrease in foraging 

effort may occur during exposure to full-array airgun firing as compared with the 

post-exposure condition, at least for some individuals; and

• knowledge of the acoustic propagation and airgun sound characteristics is critical 

to developing the capability for accurate predictions of exposures and the 

modeling of potential resulting effects.

Recommendations from the “Sperm Whale Seismic Study” included continued conservation 

of GOM sperm whales as a separate stock, implementation of a long-term monitoring program, 

continued controlled exposure experiments, investigation into sperm whale prey fields, continued 

development of tagging sensor and instrument capabilities, and continued development of passive 

acoustic monitoring techniques.
Description of the Affected Environment and Impact Analysis 4-235

In 2009, BOEM entered into an Interagency Agreement with the NMFS’s Southeast Fisheries 

Science Center for the “Sperm Whale Acoustic Prey Study.” Study objectives include quantitative 

sampling of the mid-water pelagic community within the foraging depths of sperm whales, 

examination of the relationships between acoustic backscatter and prey taxonomic composition, and 

comparison of sperm whale distribution and prey composition across habitats of the northern GOM. 

Field work is complete and sample analyses and data synthesis are ongoing.

Sirenians

The West Indian manatee typically inhabits only coastal marine, brackish, and freshwater 

areas of the southeastern U.S., the GOM, and the Caribbean Sea (Jefferson et al., 1993; O’Shea et 

al., 1995). There are two subspecies of the West Indian manatee: the Florida manatee (T. m. 

latirostris), which ranges from the northern GOM to Virginia; and the Antillean manatee 

(T. m. manatus), which ranges from northern Mexico to eastern Brazil, including the islands of the 

Caribbean Sea. The Florida manatee was listed as endangered in 1967 (Federal Register, 1967).

Manatees are generalist feeders and are known to consume more than 60 species of aquatic 

vegetation in marine, estuarine, and freshwater habitats (USDOI, FWS, 2001). Manatees primarily 

use open coastal areas and estuaries, and they are also found far up in freshwater tributaries. 

Shallow grassbeds with access to deep channels are their preferred feeding areas in coastal and 

riverine habitats (near the mouths of coastal rivers), and sloughs are used for feeding, resting, 

mating, and calving (USDOI, FWS, 2001).

Florida manatees have been divided into four distinct regional management units:

• the Atlantic Coast Unit that occupies the east coast of Florida, including the 

Florida Keys and the lower St. Johns River north of Palatka, Florida;

• the Southwest Unit that occurs from Pasco County, Florida, south to Whitewater 

Bay in Monroe County, Florida;

• 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., 2011). 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 (AlvesStanley et al., 2010). In 2013, a red-tide event in southwest Florida claimed 277 manatees. This is 
4-236 Gulf of Mexico Multisale EIS

the highest number of red-tide-related deaths in a single calendar year on record. State and Federal 

scientists are monitoring and responding to manatees affected by the ongoing red-tide bloom along 

the southwest Florida coast (State of Florida, Fish and Wildlife Conservation Commission, 2015b). 

Research into the causes of death is currently ongoing and undetermined for the No. 58 Florida 

unusual mortality event (UME). A previous UME in 2011 (No. 52) was determined to have been 

caused by ecological factors.

As of November 2015, the best available count of Florida manatees was 6,063 animals, 

based on a February 2015 aerial survey of warm water refuges (State of Florida, Fish and Wildlife 

Conservation Commission 2015c). As of November 20, 2015, of the 372 manatee carcasses 

collected in Florida, 94 of these animals died of human causes (State of Florida, Fish and Wildlife 

Conservation Commission, 2015c). The human causes identified included entrainment in watercontrol structures, entanglement in and ingestion of marine debris, entrapment in pipes/culverts, and 

collisions with watercraft. Eighty-six percent of those manatees that died of human causes were 

killed by watercraft. The remaining 278 manatee carcasses either died of natural causes (e.g., cold 

stress) or were too decomposed to accurately determine a cause of death.

Per the guidance of NTL 2012-JOINT-G01, “Vessel Strike Avoidance and Injured/Dead 

Protection Species Reporting”, an operator is to report an observation of an injured or dead 

protected species, though many operators also report live animals. Recently, three live manatees 

have been spotted offshore. The first sighting was on March 20, 2013, in Green Canyon Block 653 

in 4,356 ft (1,328 m) of water; another was on March 27, 2013, next to a drillship in approximately 

6,000 ft (1,829 m) of water; and the third was on December 18, 2013, about 16 ft (5 m) off a seismic 

vessel’s port stern in 466 ft (142 m) of water. Again, these sightings at these depths are uncommon, 

and these are the only reports of a manatee sighted by seismic observers in the GOM.

Other Protected Marine Mammal Species

One baleen cetacean (Bryde’s whale) and 19 toothed cetaceans (including beaked whales 

and dolphins, but excluding the sperm whale since they are already discussed above) occur in the 

Gulf of Mexico. None of these species are protected under the ESA; however, all marine mammals 

are protected under the Marine Mammal Protection Act (1972).

Cetaceans—Mysticetes

The only commonly occurring baleen whale in the northern GOM is the Bryde’s whale 

(Balaenoptera edeni). The Bryde’s whale is found in tropical and subtropical waters throughout the 

world. They feed on small pelagic fishes and invertebrates (Leatherwood and Reeves, 1983; 

Cummings, 1985; Jefferson et al., 1993). Bryde’s whales in the northern GOM, with few exceptions, 

have been sighted along a narrow corridor near the 100-m (328-ft) isobath (Davis and Fargion, 

1996; Davis et al., 2000). Most sightings have been made in the De Soto Canyon region and off 

western Florida, although there have been some in the west-central portion of the northeastern 

GOM.
Description of the Affected Environment and Impact Analysis 4-237

A recent study from NMFS’ Southeast Fisheries Science Center (Rosel and Wilcox, 2014) 

evaluated genetic diversity and phylogenetic distinctiveness of this population to determine how 

unique it is in comparison to other Bryde’s whales worldwide. The study found that the Gulf of 

Mexico Bryde’s whale population has little genetic diversity, suggesting a small population size and a 

history of isolation; and that the population is evolutionarily distinct from all other Bryde’s whales 

examined to date. The scientists conclude that the level of divergence suggests a unique 

evolutionary lineage for this population that is equivalent to currently recognized subspecies and 

species within the Bryde’s complex, and among species and subspecies of certain other baleen 

whales. The small population in the Gulf of Mexico, which is also morphologically and behaviorally 

distinct from others in the complex, constitutes the only known members of this unique lineage.

The GOM population is considered a separate stock (northern GOM) for management 

purposes (Waring et al., 2012). The status of Bryde’s whales in the northern GOM is unknown, as 

there are insufficient data to determine the population trends for this stock. On April 6, 2015, the 

NMFS announced a 90-day finding on a petition to list the GOM Bryde’s whale as endangered under 

the Endangered Species Act (Federal Register, 2015f).

Cetaceans—Odontocetes

Family Kogiidae: The pygmy sperm whale (Kogia breviceps) and dwarf sperm whale (Kogia 

sima) have a worldwide distribution in temperate to tropical waters (Caldwell and Caldwell, 1989). 

They feed mainly on squid but they would also eat crabs, shrimp, and smaller fishes (Würsig et al., 

2000). In the GOM, they occur primarily along the continental shelf edge and in deeper waters off 

the continental shelf (Mullin et al., 1991). At sea, it is difficult to differentiate dwarf sperm whales 

from pygmy sperm whales, and sightings are often grouped together as “Kogia spp.” Very little is 

known about the species except from studies on stranded individuals. Because information is 

incomplete or unavailable, BOEM has made conscientious efforts to comply with the spirit and intent 

of NEPA and to be comprehensive in its analyses of potential environmental impacts to poorly 

studied marine mammals.

Family Ziphiidae (Beaked Whales): Beaked whales in the GOM are identified either as 

Cuvier’s beaked whales or are grouped into an undifferentiated complex (Mesoplodon spp.) because 

of their similarity in appearance and potential identification errors. In the northern GOM, they are 

broadly distributed in waters >3,281 ft (1,000 m) over lower slope and abyssal landscapes (Davis 

et al., 1998 and 2000). Beaked whales were seen in the GOM in all seasons during GulfCet aerial 

surveys (Mullin and Hoggard, 2000). Beaked whale species that may occur within the GOM are 

usually observed singly or in small groups of individuals (Jefferson et al., 2008). As a group they are 

poorly known but are thought to be deep-diving animals. They feed at depth on deepwater 

cephalopods and fishes (Mead, 2002).

Three species of Mesoplodon are known to occur in the GOM based on sighting and 

stranding data and are considered provisional stocks (Wursig et al., 2000; Waring et al., 2014). The 

Gervais’ beaked whale (Mesoplodon europaeus) appears to be widely but sparsely distributed 
4-238 Gulf of Mexico Multisale EIS

worldwide in temperate to tropical waters (Leatherwood and Reeves, 1983). Stranding records 

suggest that this is probably the most common mesoplodont in the northern GOM (Jefferson and 

Schiro, 1997). The Blainville’s beaked whale (Mesoplodon densirostris) is distributed throughout 

temperate and tropical waters worldwide, but it is not considered common (Würsig et al., 2000). 

Cuvier’s beaked whale (Ziphius cavirorostris) is widely (but sparsely) distributed throughout 

temperate and tropical waters worldwide (Würsig et al., 2000). They are sighted in the GOM in all 

seasons in water depths typically >1,640 ft (500 m) (Maze-Foley and Mullin, 2006). Sightings data 

indicate that Cuvier’s beaked whale is probably the most common beaked whale in the GOM 

(Jefferson and Schiro, 1997; Davis et al., 1998 and 2000).

Family Delphinidae (Dolphins): Fourteen members of the dolphin family are known to occur 

in the GOM. Dolphins are often gregarious and commonly form aggregations that can range from a 

few to several thousand individuals depending on the species (Jefferson et al., 2008; Würsig et al., 

2000).

Of the 14 members, the bottlenose dolphin (Tursiops truncatus) is the most common 

inhabitant of the continental shelf and upper slope waters of the northern GOM. Bottlenose dolphins 

are opportunistic feeders, taking a wide variety of fishes, cephalopods, and shrimp (Davis and 

Fargion, 1996; Jefferson and Schiro, 1997; Wells and Scott, 1999). There appears to be two 

ecotypes of bottlenose dolphins, a coastal form (52-210 ft;16-67 m) and an offshore form (about 

820 ft; 250 m) (Hersh and Duffield, 1990; Mead and Potter, 1990; Baumgartner, 1995). The coastal 

or inshore stocks are genetically isolated from the offshore stock (Curry and Smith, 1997). Inshore 

stocks are further provisionally delineated into 32 bay, sound, and estuarine stocks (Waring et al., 

2014).

Species endemic to tropical and subtropical waters of the Atlantic Ocean include the 

Clymene dolphin (Stenella clymene) (Perrin and Mead, 1994) and pantropical spotted dolphin 

(Stenella attenuata) (Perrin and Hohn, 1994). The Clymene dolphin is thought to feed on fishes and 

cephalopods (Leatherwood and Reeves, 1983; Jefferson et al., 1993; Mullin et al., 1994b). 

Sightings in the GOM are relatively common and suggest a primary range offshore of the 100-m 

(328-ft) isobath (Davis et al., 2000; Würsig et al., 2000). The pantropical spotted dolphin feeds on 

epipelagic fishes and cephalopods (Leatherwood and Reeves, 1983; Jefferson et al., 1993). It is the 

most common cetacean in the oceanic northern GOM (Mullin et al., 1994a) and is found in the 

deeper waters off the continental shelf between the 100-m and 2,000-m (328- and 6,565-ft) depth 

contours (Mullin et al., 1994a; Davis et al., 1998 and 2000; Würsig et al., 2000).

The Atlantic spotted dolphin (Stenella frontalis), Risso’s dolphin (Grampus griseus), roughtoothed dolphin (Steno bredanensis), spinner dolphin (Stenella longirostris), striped dolphin (Stenella 

coeruleoalba), and the false killer whale (Pseudorca crassidens) are found in tropical to temperate 

waters (Jefferson and Schiro, 1997; Leatherwood and Reeves, 1983; Miyazaki and Perrin, 1994; 

Perrin and Gilpatrick, 1994; Perrin et al., 1994a; Perrin et al., 1994c). Another species, the Fraser’s 

dolphin (Lagenodelphis hosei), has a worldwide distribution in tropical waters (Perrin et al., 1994b). 

These dolphin species are known to feed on a wide variety of fishes, cephalopods, crustaceans, and 
Description of the Affected Environment and Impact Analysis 4-239

benthic invertebrates (Leatherwood and Reeves, 1983; Jefferson et al., 1993; Jefferson and Schiro, 

1997; Perrin et al., 1994a). In the GOM, they occur primarily along the continental shelf and 

continental slope (Mullin and Fulling, 2004). The rough-toothed dolphin, striped dolphin, spinner 

dolphin, and false killer whale can occur in deeper waters off the continental shelf (Davis and 

Fargion, 1996, Mullin and Fulling, 2004).

The killer whale (Orcinus orca) has a worldwide distribution from tropical to polar waters 

(Dahlheim and Heyning, 1999). They feed on marine mammals, marine birds, sea turtles, 

cartilaginous and bony fishes, and cephalopods (Leatherwood and Reeves, 1983; Jefferson et al., 

1993). In the GOM, they occur primarily in the deeper waters off the continental shelf (Davis and 

Fargion, 1996).

The melon-headed whale (Peponocephala electra) and pygmy killer whale (Feresa 

attenuata) have worldwide distributions in subtropical to tropical waters (Jefferson et al., 1992; Ross 

and Leatherwood, 1994), feeding on cephalopods and fishes (Mullin et al., 1994a; Jefferson and 

Schiro, 1997). In the GOM, they occur in the deeper waters off the continental shelf (Mullin et al., 

1994a).

The short-finned pilot whale (Globicephala macrorhynchus) is distributed worldwide in 

tropical to temperate waters (Leatherwood and Reeves, 1983). They feed predominantly on squid, 

with fishes being consumed occasionally (Würsig et al., 2000). Aggregations of short-finned pilot 

whales are commonly associated with other cetacean species (Jefferson et al., 2008). In the GOM, 

they are most frequently sighted along the continental shelf and continental slope.

Factors Influencing Cetacean Distribution and Abundance

The distribution and abundance of cetaceans within the northern GOM is strongly influenced 

by various mesoscale oceanographic circulation patterns. These patterns are primarily driven by 

river discharge (primarily the Mississippi River), wind stress, and the Loop Current and its derived 

circulation phenomena. Approximately once or twice a year, the Loop Current sheds anticyclonic 

eddies (also called warm-core rings), which, in turn, spawn cyclonic eddies (also called cold-core 

rings) during interaction with one another and upon contact with topographic features of the 

continental slope and shelf edge. These cyclonic eddies contain and maintain high concentrations 

of nutrients and stimulate localized production of phytoplankton (Davis et al., 2000), which, in turn, 

provides various food resources for various predators. River outflow also may be entrained within 

the confluence of a cyclone-anticyclone eddy pair and transported beyond the continental slope. 

Marine mammals may focus their foraging efforts on these abundant prey locations to improve 

overall efficiency and reduce energy costs (Bailey and Thompson, 2010). Other than factors 

influencing feeding behaviors, very little is known about other factors that may influence marine 

mammal distribution in the GOM because there are few studies that examine them.
4-240 Gulf of Mexico Multisale EIS

Critical Habitat

Critical habitat is designated if specific areas of habitat occupied by a species listed as 

endangered or threatened under the ESA may contain physical or biological features essential to the 

species’ conservation, and may require special management considerations or protection. The only 

marine mammal that has critical habitat currently listed within the GOM is the West Indian manatee; 

this is illustrated in Figure 4-23 (50 CFR § 17.95).

4.9.1.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from activities described in Chapter 3

and their potential impacts that would potentially result from a single lease sale or the alternatives. 

This analysis applies to all considered alternatives analyzed in Chapter 4. While the WPA is a 

smaller area with less projected activity than is proposed for the CPA/EPA (refer to Chapter 3), 

marine mammal species are widely distributed throughout the planning areas. As such, activities 

isolated to specific planning areas pose similar potential impacts to populations as do activities 

occurring in all planning areas. Therefore, because of the diversity and wide distribution of species 

in the Area of Interest, the level of impacts would be the same for Alternatives A, B, C, and D. Under 

Alternative E, there would be no new activities associated with a proposed lease sale; however, 

activities associated with past lease sales and non-OCS oil- and gas-related activities would 

continue. Following this discussion of environmental consequences, there is a more detailed 

summary of the potential impacts as they relate to the action alternatives.

As mentioned earlier in Chapter 4.9.1.1, the population estimate of a marine mammal 

species plays an important role in marine mammal management due to the fact that the same 

impact-producing factor may have a more serious impact on a marine mammal stock that has a 

lower population estimate and a less serious impact to a marine mammal stock with a higher 

population estimate. The following evaluation considers how the impact-producing factors from 

routine activities, reasonably foreseeable accidental events, and cumulative impacts from activities 

described in Chapter 3 may potentially impact a marine mammal species based on its respective 

population estimate (refer to Table 4-14 for list of marine mammal species and their respective 

population estimates).

Routine Activities

Potential impacts on marine mammal species may occur from routine activities associated 

with a proposed lease sale. As a result of OCS oil- and gas-related routine activities in the GOM, 

the major impact-producing factors affecting marine mammals include geological and geophysical 

activities, transportation, operational discharges, marine debris, decommissioning, and noise.

Geological and Geophysical Activities

Geophysical (seismic) exploration is an integral part of oil and gas discovery, development, 

and production in the GOM (refer to Chapter 3.1.2.1). With technical advances that now allow 
Description of the Affected Environment and Impact Analysis 4-241

extraction of petroleum from the ultra-deep areas of the Gulf, seismic surveys are routinely 

conducted in virtually all water depths of the GOM, including the deep habitat of the endangered

sperm whale. The impacts of noise from airguns could include one or more of the following: 

masking of natural sounds; behavioral disturbance (e.g., changes in feeding or mating behaviors); 

tolerance; and temporary or permanent hearing impairment, or nonauditory physical or physiological 

impacts (Richardson et al., 1995; Nowacek et al., 2007; Southall et al., 2007). Permanent hearing 

impairment would constitute injury; however, temporary threshold shift is not considered an injury 

(Southall et al., 2007). The only other impact-producing factor to marine mammals that is associated 

with G&G activities is the potential for gear interaction. Marine mammals can become entangled in 

some types of lines associated with G&G activities. The G&G permit applications are reviewed by 

BOEM and the NMFS to set conditions of approval with each activity that would minimize impacts 

caused by gear interactions which are expected to be rare.

The NTL 2012-JOINT-G02, “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program,” provides guidance to protect marine mammals and sea 

turtles during seismic operations. This NTL clarifies how operators should implement seismic survey 

mitigating measures, including ramp-up procedures, the use of a minimum sound source, airgun 

testing, and protected species observation and reporting. The Protected Species Stipulation, if 

applied, would make compliance with the guidance identified in the NTL mandatory for lessee 

activities. For more information about G&G activities, refer to the Geological and Geophysical 

Exploration for Mineral Resources on the Gulf of Mexico Outer Continental Shelf: Final 

Programmatic Environmental Assessment, (USDOI, MMS, 2004b). In addition, the NMFS, BOEM, 

and BSEE collaborated to publish National Standards for a Protected Species Observer Program to 

reduce impacts to protected species from G&G activities by standardizing the variation in and 

improving the management of the program (Baker et al., 2013).

Without implementation of BOEM’s mitigations, marine mammals would be vulnerable to 

impacts from the noise produced from airguns, vessel strikes, and entanglement from gear 

interaction. The impacts from these factors with mitigations mentioned above would be expected to 

be negligible to moderate. Although mitigations may drastically reduce potential impacts to marine 

mammals from G&G activities, they do not eliminate them completely and could have a moderate 

impact on marine mammal species. For example, if an individual bottlenose dolphin would become 

entangled from gear interaction, some impacts may result in physical injury or mortality. However, 

with the use of ramp-up procedures, minimum sound sources, airgun testing, and protected species 

observation and reporting, it is reasonably foreseeable that marine mammals would be detected and 

that proper procedures, including shutdowns, would be used to avoid any impacts, making them 

negligible. 

Transportation

The oil and gas industry uses a variety of vessels running from shore bases to offshore OCS 

oil and gas structures (refer to Chapter 3.1.4). Increased traffic from service and support vessels 

would increase the probability of collisions between vessels and marine mammals. These collisions 
4-242 Gulf of Mexico Multisale EIS

can cause major injuries and/or fatalities (e.g., the sperm whale [Waring et al., 2013] and bottlenose 

dolphin [Fertl, 1994]). Slow-moving cetaceans or those that spend extended periods of time at the 

surface might be expected to be the most vulnerable (Vanderlaan and Taggert, 2007). Smaller 

delphinids often approach vessels that are in transit to bow-ride; however, vessel strikes are less 

common for these faster moving mammals or are underreported (Wells and Scott, 1997). Nowacek 

and Wells (2001) found that bottlenose dolphins had longer interbreath intervals during boat 

approaches compared with control periods (no boats present within 100 m [328 ft]) in a study 

conducted in Sarasota Bay, Florida. They also found that dolphins’ decreased interanimal distance, 

changed heading, and increased swimming speed significantly more often in response to an 

approaching vessel than during control periods.

Collisions of vessels with marine mammals are not uncommon (Laist et al., 2001). 

Vanderlaan and Taggert (2007) examined the literature for large whale species and reported that the 

probability for vessel strikes is largely a function of vessel speed. Data compiled by Laist et al. 

(2001) indicate that relatively large (>80 m; 262 ft) and fast-moving vessels (>14 kn; 16 mph) are 

most commonly involved in collisions with marine mammals. They also conclude that the majority of 

collisions appear to occur over or near the continental shelf and that the whales usually are not seen 

beforehand or are seen too late to be avoided. The rapid increase in exploration and development 

of petroleum resources in deep oceanic waters of the northern Gulf has increased the risk of OCS 

vessel collisions with sperm whales and other deep-diving cetaceans (e.g., Kogia and beaked 

whales). Deep-diving whales may be more vulnerable to vessel strikes because of the extended 

surface period required to recover from extended deep dives. Although the sperm whale is the most 

likely large whale to be struck by a vessel in the GOM, there has only been one possible mortality 

due to vessel strike documented as of 2012 (Waring et al., 2013). Sperm whales have been shown 

to be unable to outmaneuver a fast vessel approaching under stratified water conditions (Gannier 

and Marty, 2015).

Florida manatees are commonly found in shallow coastal waters of Florida, but they have 

been found along the entire northern GOM from Florida to Texas (Fertl et al., 2005), though some 

recent deepwater sightings have occurred. Vessel strikes are the most common cause of humaninduced mortality for manatees (State of Florida, Fish and Wildlife Conservation Commission, 

2015c), and most manatees bear prop scars from contact with vessels. The vast majority of strikes 

result from recreational and fishing vessels, not those related to oil and gas activities. Service and 

support vessels traveling through coastal areas to and from oil and gas structures have the rare 

potential to impact manatees by vessel collisions. In 1995, for example, an oil crew workboat struck 

and killed a manatee in a canal near coastal Louisiana (Fertl et al., 2005). Inadequate hearing 

sensitivity at low frequencies (Gerstein et al., 1999), slow movement, and use of shallow and surface 

waters are contributing factors to their vulnerability to vessel strike impacts. While manatees are 

less common in the western Gulf, they are being seen more frequently, and increased sightings 

indicate that there is a potential for risks to this species from OCS vessel traffic. There is the 

possibility of short-term disruption of movement patterns and/or behavior caused by vessel noise 

and disturbance; however, these are not expected to impact survival and growth of manatees in the 

GOM.
Description of the Affected Environment and Impact Analysis 4-243

Expected industry service trip numbers as a result of Alternative A, B, C, or D are described 

in Chapter 3.1.4.5 (Table 3-2). BOEM and BSEE issued NTL 2012-JOINT-G01, “Vessel Strike 

Avoidance and Injured/Dead Protected Species Reporting,” which explains how operators must 

implement measures to minimize the risk of vessel strikes to protected species and to report 

observations of injured or dead protected species. The Protected Species Stipulation, if applied, 

would make compliance with the guidance identified in the NTL mandatory for lessee activities. 

Adherence to the NTL protocols is expected to reduce but not eliminate the risk of potential vessel 

strikes with marine mammals.

Without implementation of mitigations, marine mammals would be vulnerable to direct 

impacts from vessel strikes. The impacts from these factors with mitigations are expected to be 

negligible to major. Although mitigations may drastically reduce potential impacts to marine 

mammals from vessel strikes, they do not completely eliminate the risk. Therefore, depending on 

the population estimate of any given species, vessel strikes could have a major impact. For 

example, if an individual Bryde’s whale (population estimate of 33 individuals) were to be struck by a 

vessel, some impacts may result in physical injury or mortality. Because the population estimate is 

so low for this species, a mortality on an individual would diminish the continued viability of the 

population, including the annual rates of recruitment or survival. However, with the use of vessel 

strike avoidance guidelines, it is reasonably foreseeable that marine mammals would be detected 

and that proper procedures, including reduced speed, change in course, or shutdown, would be 

used to avoid impacts to marine mammals, which would be negligible.

Discharges and Wastes

The primary operational waste discharges generated during offshore oil and gas exploration 

and development are drilling fluids, drill cuttings, produced water, deck drainage, sanitary wastes, 

and domestic wastes (refer to Chapter 3.1.5). During production activities, additional waste streams 

include well treatment, workover, and completion fluids. Minor additional discharges occur from 

numerous sources; these discharges may include desalination unit discharges, blowout preventer 

fluids, boiler blowdown discharges, excess cement slurry, and uncontaminated freshwater and 

saltwater. Discharges are regulated by the USEPA through the issuance of NPDES permits. 

Pollutants discharged into navigable waters of the U.S. are regulated by the USEPA under the Clean 

Water Act of 1972 and subsequent provisions (33 U.S.C. § 1251 et seq.). Specifically, an NPDES 

permit must be obtained from the USEPA under Sections 301(h) and 403 (Federal Register, 1980) 

of the Clean Water Act (refer to Chapter 4.2, Water Quality).

Heavy metal accumulations in marine mammal tissues are of concern worldwide (Bossart, 

2006). Trace metals, including mercury, in drilling discharges have been a particular concern. 

However, Neff et al. (1989) concluded that metals associated with drilling fluid were virtually 

nonbioavailable to marine organisms. Marine mammals generally are inefficient assimilators of 

petroleum compounds in prey (Neff, 1990). Analyses of samples from live GOM and Atlantic 

bottlenose dolphins showed high levels of polyfluoroalkyl compounds (Houde et al., 2005). Recent 

work by Kucklick et al. (2011) in the GOM identified a number of persistent organic pollutants in 
4-244 Gulf of Mexico Multisale EIS

bottlenose dolphins, and Fair et al. (2010) documented unusually high levels of organic chemicals in 

bottlenose dolphins in Atlantic populations. Adequate baseline data are not available to determine 

the significant sources of contaminants that accumulate in GOM cetaceans or their prey, due in no 

small part to the fact that contaminants are introduced into the GOM from a variety of national 

watersheds. Many cetaceans are wide-ranging animals, which also compounds the issue. Coastal 

cetacean species tend to have higher levels of metals than those frequenting oceanic waters 

(Johnston et al., 1996). Oceanic cetaceans feeding on cephalopods have higher levels of cadmium 

in their tissues than comparable fish-eating species (Johnston et al., 1996). There also is, in many 

cases, a striking difference between the relatively high mercury levels in the toothed whales and the 

lower levels found in baleen whales, which is probably attributable to the different prey species 

consumed by baleen whales, as well as differences in the habitat (Johnston et al., 1996).

Most operational discharges are diluted and dispersed when released in offshore areas, and 

they are not expected to directly affect any marine mammal species (Kennicutt, 1995). Any potential 

impacts from drilling fluids would be indirect, either as a result of impacts to prey species or possibly 

through ingestion via the food chain (Neff et al., 1989). Contaminants in drilling muds or waste 

discharge may biomagnify and bioaccumulate in the food web, which may kill or debilitate important 

prey species of marine mammals or species lower in the marine food web. Releases of toxic 

discharges are regulated by the USEPA through the issuance of NPDES permits to keep 

contaminants below harmful levels. These regulations and permit provisions are designed to 

prevent unreasonable degradation of the marine environment, and adherence to these requirements 

by industry would be expected to result in limited impacts to water quality, and therefore, indirect 

impacts to marine mammals would likewise be small. Without implementation of requirements, 

marine mammals would be vulnerable to direct and indirect impacts from operational discharges. 

The impacts from these factors are, therefore, expected to be negligible given assumed compliance 

with existing regulations and permit requirements.

Marine Trash and Debris

Marine mammal ingestion of, and entanglement in, accidentally released industry debris is a 

concern (refer to Chapter 3.1.5.3.4). A marine mammal could suffer reduced feeding and 

reproductive success, and potential injury, infection, and death from entanglement in marine debris. 

The debris items most often found entangling animals are net fragments and monofilament line from 

commercial and recreational fishing boats, as well as strapping bands and ropes from a variety of 

vessels. Plastic bags and small plastic fragments are the most commonly reported debris items in 

the digestive tracts of cetaceans and manatees (e.g., Barros and Odell, 1990; Tarpley and Marwitz, 

1993; Laist, 1997); however, ingestion of net materials can also be fatal (Jacobsen et al., 2010). 

Sheavely (2007) reports that as much as 49 percent of marine debris is considered land based. 

There are many types of materials used in offshore energy production and some of this material is 

accidentally lost overboard from service vessels or OCS structures where marine mammals could 

ingest it or become entangled in it. The offshore oil and gas industry was shown to contribute 

13 percent of the debris found at Padre Island National Seashore (Miller et al., 1995). Many of the 

plastics used by industry could withstand years of saltwater exposure without disintegrating or 
Description of the Affected Environment and Impact Analysis 4-245

dissolving. To address the potential impacts of marine debris, the BSEE issued NTL 2012-BSEEG01, “Marine Trash and Debris Awareness and Elimination,” which provides information on the 

marine trash and debris awareness training video and slide show, and both postal and email 

addresses for submitting annual training reports. The information provided is intended to greatly 

minimize the amount of debris that is accidentally lost overboard by offshore personnel; however, 

these directives do not eliminate the accidental release of debris, which could impact an individual or 

group of individuals if they become entangled in or ingest accidentally released debris. The 

Protected Species Stipulation, if applied, would make compliance with the guidance identified in the 

NTL mandatory for lessee activities.

Without implementation of mitigations, marine mammals would be vulnerable to direct 

impacts from entanglement in or ingestion of marine debris. The impacts from these factors with 

mitigations are expected to be negligible to major. Although mitigations may drastically reduce 

potential impacts to marine mammals from marine debris, they do not completely eliminate the risk. 

Therefore, depending on the population estimate of any given species, marine debris could have a 

major impact. For example, if an individual Bryde’s whale (population estimate of 33 individuals) 

were to ingest or become entangled in marine debris, some impacts may result in physical injury or 

mortality. Because the population estimate is so low for this species, this would diminish the 

continued viability of the population, including the annual rates of recruitment or survival. However, 

with the use of marine trash and debris guidelines, it is reasonably foreseeable that marine 

mammals would not encounter OCS oil- and gas-related marine trash or debris, which would result 

in a negligible impact.

Decommissioning

The use of explosives is one of industry’s preferred methods for the severance of structures 

from their foundations in the GOM (refer to Chapter 3.1.6). It has been demonstrated that nearby 

underwater blasts can injure or kill marine mammals (Richardson et al., 1995). Injuries from highvelocity underwater explosions result from two factors: (1) the very rapid rise time of the shock 

wave; and (2) the negative pressure wave generated by the collapsing bubble, which is followed by 

a series of decreasing positive and negative pressure pulses (USDOI, MMS, 2004b). The extent of 

injury largely depends on the intensity of the shock wave and the size and depth of the animal at the 

time of the detonation (Yelverton et al., 1973).

BOEM (then BOEMRE) issued “Decommissioning Guidance for Wells and Platforms” (NTL 

2010- BSEE-G05) to offshore operators; it provides clarification and interpretation of regulations 

regarding decommissioning, as well as guidance to operators proposing to use explosives to 

perform well/casing severance. These guidelines specify and reference mitigation, monitoring, and 

reporting requirements. As noted in Chapter 3.1.6, decommissioning for wells and platforms are 

site specific and are reviewed by the BSEE and BOEM.

Expected numbers of production structures to be removed using explosives as a result of 

Alternative A, B, C, or D are reported in Chapter 3.1.4.5. Explosive severance could moderately 
4-246 Gulf of Mexico Multisale EIS

impact marine mammals; however, with implementation of the Bureau of Safety and Environmental 

Enforcement’s NTL guidelines and regulations, and NMFS’s Observer Program for explosive 

removal, impacts to marine mammals from explosive severance are expected to be negligible to 

moderate. Although the NTL’s guidelines and regulations, along with the NMFS’s Observer program 

for explosive removal, would greatly reduce impacts of decommissioning activities to marine 

mammals, they may not be completely eliminated. To date, there are no documented “takes” of 

marine mammals resulting from explosive removals of offshore structures. Decommissioning 

activities and their potential impacts to different marine mammal species are described further in the 

Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf: Programmatic 

Environmental Assessment (USDOI, MMS, 2005), as well as in Chapter 3. In addition, a 

site-specific NEPA analysis, in the form of an EA or EIS, is completed for all structure removals that 

propose explosive severance methods and/or site-clearance trawling. Without implementation of 

mitigations, marine mammals would be vulnerable to direct impacts from explosive charges used for 

the removal of production structures. The impacts from these factors with mitigations are expected 

to be negligible to moderate. Although mitigations may drastically reduce potential impacts to 

marine mammals from explosive severance methods, they do not completely eliminate the risk. 

Therefore, depending on the population estimate of any given species, explosive severance 

methods could have a major impact. For example, if a group of pantropical spotted dolphins 

(population estimate of 50,880 individuals) were not detected prior to a detonation and experienced 

physical injuries or mortalities, it would have a localized and irreversible impact on that group of 

individuals, but it would not diminish the continued viability of the population. However, with the use 

of decommissioning guidelines, as well as the fact that there have been no documented “takes” of 

marine mammals, it is reasonably foreseeable that decommissioning activities would have a 

negligible impact.

Noise

Aircraft overflights (either helicopter or fixed-wing) in close proximity to marine mammals 

may elicit a startle response due to either the increasing noise as the aircraft approaches or due to 

the physical presence of the aircraft in the air. Refer to Chapter 3.1.9 for more information on OCS 

oil- and gas-related noise. With more than 1 million helicopter take offs/landings expected per year 

from activity related to past, proposed, and future lease sales, the OCS industry’s activity contributes 

greatly to this noise source. Although air traffic offshore is limited, the military maintains 11 military 

warning areas and 6 water test areas in the GOM (Figure 2-7). Some commercial fisheries include 

aerial surveillance. Scientific research aerial surveys are occasionally scheduled over the GOM. 

Commercial and private aircraft also traverse the area.

Marine mammals often react to aircraft overflights by hasty dives, turns, or other abrupt 

changes in behavior. Responsiveness varies widely depending on factors such as species, the 

activity the animals are engaged in, and water depth (Richardson et al., 1995). Marine mammals 

engaged in feeding or social behavior are often insensitive to overflights, while those in confined 

waters or those with calves may be more responsive. The impacts appear to be transient, and there 

is no indication that long-term displacement of marine mammals occurs. However, the absence of 
Description of the Affected Environment and Impact Analysis 4-247

conspicuous response does not show that the animals are unaffected; it is not known whether these 

subtle impacts are biologically significant (Richardson and Würsig, 1997). Because information is 

incomplete or unavailable, BOEM has made conscientious efforts to comply with the spirit and intent 

of NEPA and to be comprehensive in its analyses of potential environmental impacts of aircraft noise 

to marine mammals.

Aircraft noise is generally short in duration and transient in nature, although it may ensonify 

large areas. Much of the noise from a passing aircraft is reflected and does not penetrate the water 

(Urick, 1972). Helicopter noises contain dominant tones (resulting from rotors) generally below 500 

Hz (Richardson et al., 1995). The Federal Aviation Administration’s Advisory Circular 91-36D (2004) 

encourages pilots to maintain an altitude of higher than 2,000 ft (610 m) over noise-sensitive areas. 

Corporate helicopter policy states that helicopters should maintain a minimum altitude of 700 ft 

(213 m) while in transit offshore and 500 ft (152 m) while working between platforms. It is unlikely 

that marine mammals would be affected by routine OCS helicopter traffic operating at these 

altitudes. Routine overflights may elicit a startle response from and interrupt marine mammals 

nearby (depending on the activity of the animals), possibly causing temporary displacement from 

feeding, mating, or traveling activities. This temporary disturbance to marine mammals may occur 

as helicopters approach or depart OCS oil- and gas-related facilities if animals are near the facility. 

Without implementation of guidelines and regulations by the NMFS under the authority of the MMPA, 

marine mammals would be vulnerable to direct impacts from routine overflights. The impacts from 

these factors with these guidelines and mitigations are expected to be negligible. 

The dominant source of human noise in the sea is ship noise (Tyack, 2008). The primary 

sources of vessel noise are propeller cavitation, propeller singing, and propulsion; other sources 

include auxiliaries, flow noise from water dragging along the hull, and bubbles breaking in the wake 

(Richardson et al., 1995). The intensity of noise from service vessels is roughly related to ship size 

and speed. Large ships tend to be noisier than small ones, and ships underway with a full load (or 

towing or pushing a load) produce more noise than unladed vessels. For a given vessel, relative 

noise also tends to increase with increased speed. The ambient noise environment in the GOM is 

filled with ship “noise” associated with oil- and gas-related activities, shipping, and recreational 

vessels, raising concerns that elevated levels of noise may interfere with the behavior and 

physiology of marine mammals (Tyack, 2008). Many of the industry-related noises are believed to 

be out of, or on the limits of, marine mammal hearing, and the sounds are also generally temporary. 

Impacts from vessel noise could disturb animals in the immediate vicinity of the vessel; however, the 

noise would be transitory in nature. Further detailed information on marine mammal hearing may be 

found in BOEM’s Atlantic OCS Proposed Geological and Geophysical Activities: Mid-Atlantic and 

South Atlantic Planning Areas, Final Programmatic Environmental Impact Statement, which can be 

found on BOEM’s website (USDOI, BOEM, 2014a).

Andrew et al. (2002) reported that, over a 33-year period, increases in shipping noise levels 

in the ocean may account for a 10-decibel (dB) increase in ambient noise between 20 and 80 Hz 

and between 200 and 300 Hz, and a 3-dB increase in noise at 100 Hz on the continental slope of 

Point Sur, California. Although comparable baseline data are not available for the GOM, it is likely 
4-248 Gulf of Mexico Multisale EIS

that similar ambient noise increases have occurred. Much of the change is expected to be 

attributable to commercial shipping (greater numbers of ships in the GOM and larger ship size are 

both factors). However, the expansion of oil and gas industry activities, including more structures, 

more exploration (seismic surveys) and drilling, a larger service boat fleet, and much greater 

distances to travel to deepwater installations, has also contributed to more noise in GOM waters.

Evidence suggests that some whale species have reduced their use of certain areas heavily 

utilized by ships (Richardson et al., 1995), possibly avoiding or abandoning important feeding areas, 

breeding areas, resting areas, or migratory routes. The continued presence of various cetacean 

species in areas with heavy vessel traffic indicates a considerable degree of tolerance to vessel 

noise and disturbance. Vessel noise could interfere with marine mammal communication either by 

masking important sounds from conspecifics, masking sounds from predators, or by forcing animals 

to alter their vocalizations (Tyack, 2008). There is the possibility of short-term disruption of 

movement patterns and/or behavior caused by vessel noise and disturbance; however, these are not 

expected to impact survival and growth of any marine mammal populations in the GOM. BOEM and 

BSEE issued NTL 2012-JOINT-G01, “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting,” explains how operators must implement measures to minimize the risk of vessel strikes 

to protected species and report observations of injured or dead protected species. This guidance 

should also minimize the chance of marine mammals being subject to the increased noise level of a 

service vessel in very close proximity. The Protected Species Stipulation, if applied, would make 

compliance with the guidance identified in the NTL mandatory for lessee activities.

Without implementation of the guidance mentioned above to avoid marine mammals, marine 

mammals would be vulnerable to direct noise impacts from routine vessel traffic, resulting in shortterm disruptions of movement patterns or behaviors. However, with the use of the guidelines 

mentioned above to minimize the chance of marine mammals being subjected to increased noise 

levels from service vessels, the impacts are expected to be negligible. 

Drilling and production activities, which include operating platforms and drillships, produce 

underwater noise that may be detected by marine mammals. The OCS industry’s drilling and 

production impacts are discussed in Chapter 3.1.2.2 and 3.1.3. Noises produced by these types of 

activities are generally low frequency and have the potential to mask cetaceans’ reception of sounds 

produced for echolocation and communication. Most species of marine mammals in the GOM 

(except the Bryde’s whale) use sounds at frequencies that are generally higher than the dominant 

noise generated by offshore drilling and production activities. Baleen whales use low-frequency 

sounds that overlap broadly with the dominant frequencies of many industrial sounds, and there are 

indications that baleen whales are sensitive to low- and moderate- frequency sounds (Richardson 

et al., 1995). However, all baleen whale species, except for the Bryde’s whale, are considered 

extralimital or rare in the GOM. There is a small population of Bryde’s whales in the GOM that may 

represent a resident stock, but there is no information on stock differentiation (Waring et al., 2013). 

It is expected that noise from drilling activities would be relatively constant during the temporary 

duration of drilling. Drilling noise from conventional metal-legged structures and semisubmersibles 

is not particularly intense and is strongest at low frequencies, averaging 5 Hz and 10-500 Hz, 
Description of the Affected Environment and Impact Analysis 4-249

respectively (Richardson et al., 1995). Drillships produce higher levels of underwater noise than 

other types of platforms. There are few published data on underwater noise levels near production 

platforms and on the marine mammals near those facilities (Richardson et al., 1995). However, 

underwater strong noise levels may often be low, steady, and not very disturbing (Richardson et al., 

1995). Stronger reactions would be expected when sound levels are elevated by support vessels or 

other noisy activities (Richardson et al., 1995).

Noise from drilling and production operations may impact marine mammals similarly to other 

anthropogenic sounds in the ocean. Noise can mask important sounds from conspecifics (a 

member of the same species), mask sounds from predators, or force animals to alter their 

vocalizations. Noises may frighten, annoy, or distract marine mammals and lead to physiological 

and behavioral disturbances. The response threshold may depend on whether habituation (gradual 

waning of behavioral responsiveness) or sensitization (increased behavioral responsiveness) occurs 

(Richardson et al., 1995). Noises can cause reactions that might include the disruption of marine 

mammals’ normal activities (behavioral and/or social disruption) and, in some cases, short- or longterm displacement from areas important for feeding and reproduction (Richardson et al., 1995). The 

energetic consequences of one or more disturbance-induced periods of interrupted feeding or rapid 

swimming, or both, have not been evaluated quantitatively. Some demographic groups may be 

more vulnerable to noise impacts, including females in late pregnancy or lactating. Human-made 

noise may cause temporary or permanent hearing impairment in marine mammals if the noise is 

strong enough. Such impairment would have the potential to diminish the individual’s chance for 

survival. Tolerance of noise is often demonstrated, but marine mammals may be affected by noise 

in difficult-to-observe ways. For example, they may become stressed, making the animal(s) more 

vulnerable to parasites, disease, environmental contaminants, and/or predation. Noise-induced 

stress is possible, but it is little studied in marine mammals. Tyack (2008) suggests that a more 

significant risk to marine mammals from sound are these less visible impacts of chronic exposure. 

Drilling and production noise would contribute to increases in the ambient noise environment of the 

GOM, but they are not expected in amplitudes sufficient to cause either hearing or behavioral 

impacts. Expected numbers of exploration and delineation wells, as well as development wells, 

projected to be drilled as a result of Alternative A, B, C, or D can be found in Chapter 3.1.4.5. 

The temporary and transient noise associated with drilling and production is not expected to 

produce more than negligible to minor impacts on marine mammals since they are not expected in 

amplitudes sufficient to cause hearing behavioral effects and due to the wide-ranging behavior of 

marine mammal species.

Although there would always be some level of incomplete information on the impacts from 

routine activities under a proposed action on marine mammals, there is credible scientific 

information, applied using acceptable scientific methodologies, to support the conclusion that any 

realized impacts would be sublethal in nature and not in themselves rise to the level of reasonably 

foreseeable significant adverse (population-level) effects. There are no data to suggest that routine 

activities from the preexisting OCS Program are significantly impacting marine mammal populations.
4-250 Gulf of Mexico Multisale EIS

Accidental Events

Accidental, unexpected events reasonably foreseeable as a result of a proposed lease sale 

could negatively impact marine mammals. Such impacts would primarily be the result of oil spills 

and spill-response activities.

Oil Spills

Improperly balanced well pressures that result in sudden, uncontrolled releases of fluids from 

a wellhead or wellbore could occur during any phase of development, i.e., exploratory drilling, 

development drilling, production, completion, or workover operations. In the event of an accidental 

spill, the eruption of gases and fluids may generate significant pressure waves and noise that may 

harass, injure, or kill marine mammals, depending on their proximity to the accident. The probability 

that a marine mammal would be in the vicinity of a loss of well control at the exact moment it occurs 

is relatively small due to the wide-ranging behavior of marine mammal species, along with the low 

probability of a loss of well control (refer to Chapter 3.1.2 for more information on oil spills).

The impacts of an oil spill on marine mammals depend on many variables, such as location 

and size of the spill, oil characteristics, weather and water conditions, time of year, and types of 

habitats, as well as the behavior and physiology of the marine mammals themselves (Johnson and 

Ziccardi, 2006). The oil from a spill can adversely affect marine mammals by causing soft-tissue 

irritation, fouling of baleen plates, respiratory stress from the inhalation of toxic fumes, food reduction 

or contamination, direct ingestion of oil and/or tar, and temporary displacement from preferred 

habitats. The long-term impacts to marine mammal populations are poorly understood but could 

include decreased survival and lowered reproductive success (Matkin et al., 2008). An oil spill may 

physiologically stress an animal (Geraci and St. Aubin, 1980), making it more vulnerable to disease, 

parasitism, environmental contaminants, and/or predation. In any case, the impact could negatively 

impact a marine mammal population or stock.

The resident marine mammal species in the GOM include a baleen whale, toothed whales, 

delphinids, and a sirenian. Baleen whales are particularly vulnerable to direct impacts from fouling 

of baleen plates, which could impact feeding behavior. Marine mammals may have direct contact 

with oil by swimming through oil on the surface and/or subsurface. Surfacing behavior exposes skin, 

eyes, nares, and other mucus membranes to volatile hydrocarbons. This contact with oil could 

cause soft-tissue damage to eye tissues, potentially leading to ulcers, conjunctivitis, or blindness. 

Most of the information on the potential impacts of oil on marine mammals comes as a result of the 

Exxon Valdez oil spill in Alaska and some limited exposure experiments (Geraci and St. Aubin, 

1990).

Fresh crude oil or volatile distillates release toxic vapors that, when inhaled, can lead to 

irritation of respiratory membranes, lung congestion, and pneumonia. Subsequent absorption of 

volatile hydrocarbons into the bloodstream may accumulate into such tissues as the brain and liver, 

causing neurological disorders and liver damage (Geraci and St. Aubin, 1982; Hansen, 1985; 

Geraci, 1990). Toxic vapor concentrations just above the water’s surface (where cetaceans draw 
Description of the Affected Environment and Impact Analysis 4-251

breath) may reach critical levels for the first few hours after a spill, prior to evaporation and 

dispersion of volatile aromatic hydrocarbons and other light components (Geraci and St. Aubin, 

1982).

Studies by Geraci and St. Aubin (1982 and 1985) have shown that the cetacean epidermis 

functions as an effective barrier to many of the toxic substances found in petroleum. This barrier is a 

result of tight intercellular bridges, the vitality of the superficial cells, the thickness of the epidermis, 

and the lack of sweat glands and hair follicles (Geraci and St. Aubin, 1985). The cetacean epidermis 

is nearly impenetrable, even to the highly volatile compounds in oil, and when skin is breached, 

exposure to these compounds does not impede the progress of healing (Geraci and St. Aubin, 

1985). Marine mammals are more likely to have dermal contact with weathered oil, which is more 

persistent but contains fewer of the toxic compounds found in fresh oil (Geraci and St. Aubin, 1990). 

Dolphins maintained at a captive site that were exposed to petroleum products initially exhibited a 

sharp decrease of food intake, along with excited behavior, eye inflammation, and changes in 

hemoglobin as well as erythrocyte content (Lukina et al., 1996). Prolonged exposure to oil led to a 

decrease of those blood parameters, changes in breathing patterns and gas metabolism, depressed 

nervous functions, and the appearance of skin injuries and burns (Lukina et al., 1996).

Trained, captive bottlenose dolphins exposed to oil could not detect light oil sheen but could 

detect thick dark oil based on visual, tactile, and presumably echolocation cues (Geraci et al., 1983; 

Smith et al., 1983). Studies of captive dolphins also showed that they completely avoided surfacing 

in slick oil after a few brief, initial tactile encounters. Reactions of free-ranging dolphins to spilled oil 

appear varied, ranging from avoidance to apparent indifference (reviewed by Geraci, 1990; Smultea 

and Würsig, 1991). In contrast to captive dolphins, bottlenose dolphins were observed off 

Galveston, Texas, during the Mega Borg oil spill in the summer of 1990 and did not consistently 

avoid entering the slick oil, which could increase their vulnerability to potentially harmful exposure to 

oil chemicals (Smultea and Würsig, 1991 and 1995). It is possible that some overriding behavioral 

motivation (such as feeding) induced dolphins to swim through the oil, that slick areas were too large 

for dolphins to feasibly avoid, or that bottlenose dolphins have become accustomed to oil due to the 

extent of oil-related activity in the GOM (Smultea and Würsig, 1995). After the Exxon Valdez spill, 

killer whales did not appear to avoid oil; however, none were observed in heavier slicks of oil (Matkin

et al., 1994). It is unknown whether animals in some cases are simply not affected by the presence 

of oil, or perhaps are even drawn to the area in search of prey organisms attracted to the oil’s 

protective surface shadow (Geraci, 1990). The probable impacts on cetaceans swimming through 

an area of oil would depend on a number of factors, including ease of escape from the vicinity, the 

health of the individual animal, and its immediate response to stress (Geraci and St. Aubin, 1985).

Manatees concentrate their activities in coastal waters, often resting at or just below the 

surface, which may bring them in contact with spilled oil (St. Aubin and Lounsbury, 1990). Types of 

impacts to manatees from contact with oil include (1) asphyxiation due to inhalation of hydrocarbons, 

(2) acute poisoning due to contact with fresh oil, (3) lowering of tolerance to other stress due to the 

incorporation of sublethal amounts of petroleum components into body tissues, (4) nutritional stress 

through damage to food sources, and (5) inflammation or infection and difficulty eating due to oil 
4-252 Gulf of Mexico Multisale EIS

sticking to the sensory hairs around their mouths (Preen, 1989, in Sadiq and McCain, 1993). Direct 

contact with discharged oil likely does not impact adult manatees’ thermoregulatory abilities because 

they use blubber for insulation. Also, they exhibit no grooming behavior that would contribute to 

ingestion (USDOI, FWS, 2006). Manatees are nonselective, generalized feeders that might 

consume tarballs along with their normal food, although such occurrences have been rarely reported 

(review in St. Aubin and Lounsbury, 1990). A manatee might also ingest fresh petroleum, which 

some researchers have suggested might interfere with the manatee’s secretory activity of their 

unique gastric glands or harm intestinal flora vital to digestion (Geraci and St. Aubin, 1980; 

Reynolds, 1980). Spilled oil may also affect the quality or availability of aquatic vegetation, including 

seagrasses, upon which manatees feed.

There have been no experimental studies and only a few observations suggesting that oil 

has harmed any manatees (St. Aubin and Lounsbury, 1990), although for a population under 

pressure from other mortality factors (e.g., vessel strikes), even a localized incident could be 

significant (St. Aubin and Lounsbury, 1990). Oil spills that may occur from OCS energy-related 

activities that reach the coast or the confines of preferred river systems and canals, particularly 

during winter (when the animals are most vulnerable physiologically), could further endanger local 

populations. The physiological costs of animals moving to colder waters to escape oiled areas may 

result in thermal stress that would exacerbate the impacts of even brief exposure to oil (St. Aubin 

and Lounsbury, 1990).

Indirect consequences of oil pollution on marine mammals include those impacts that may be 

associated with changes in the availability or suitability of food resources (Hansen, 1992). Spilled oil 

can lead to the localized reduction, disappearance, or contamination of some prey species. Prey 

species such as zooplankton, crustaceans, mollusks, and fishes may become contaminated by 

direct contact and/or by ingesting oil droplets and tainted food. Marine fishes are known to take up 

petroleum hydrocarbons from both water and food, although apparently do not accumulate high 

concentrations of hydrocarbons in tissues, and may transfer them to predators (Neff, 1990). In 

general, the potential for ingesting oil-contaminated prey organisms with petroleum-hydrocarbon, 

body-burden content is highest for benthic-feeding whales, which are not common in the GOM. The 

potential is reduced for plankton-feeding whales and is lowest for fish-eating whales (Würsig, 1990). 

An analysis of stomach contents from captured and stranded toothed whales suggest that they are 

deep-diving animals, feeding predominantly on mesopelagic fish and squid or deepwater benthic 

invertebrates (Heyning, 1989; Mead, 1989). Depending on the spatial scale and magnitude of an oil 

spill, diminished prey abundance and availability may cause marine mammal predators to move to 

less suitable areas and/or consume less suitable prey.

Several factors increase the probability of marine mammal/oil-spill contact, 

including:(1) marine mammals often travel long distances in the GOM, increasing the geographic 

areas of potential impact; (2) marine mammals are relatively long-lived and have many years during 

which they may be exposed; (3) the life of a proposed action also means many years for an impact 

to occur; and (4) some spills would be larger, increasing the area of potential impact. It is impossible 

to know precisely which cetacean species, population, or individuals would be most impacted, to 
Description of the Affected Environment and Impact Analysis 4-253

what magnitude, or in what numbers since each species has unique distribution patterns in the GOM 

and because of difficulties attributed to predicting when and where oil spills would occur over the 50-

year lifetime of a proposed action. The potential impacts associated with an accidental spill may be 

more severe depending on the size of the reasonably foreseeable accidental spill. The impact from 

a reasonably foreseeable, higher volume accidental spill could potentially contribute to more 

significant and longer-lasting impacts that could include mortality and longer-lasting chronic or 

sublethal impacts.

Given the distribution of available leases and pipelines associated with a proposed lease 

sale and the distribution of marine mammals in the northern GOM, the fate of an oil spill must be 

considered relative to the region and period of exposure. Spills of any size can degrade water 

quality at least locally (Chapter 4.2, Water Quality), and residuals become available for 

bioaccumulation within the food chain. Slicks may spread at the sea surface or may migrate 

underwater from the seafloor through the water column and never broach the sea surface. 

Regardless, a slick is an expanding but aggregated mass of oil that, with time, would disperse into 

smaller units as it evaporates (if at the sea surface) and weathers. As the slick breaks up into 

smaller units (e.g., slickets) and soluble components dissolve into the seawater, tarballs may remain 

within the water column. Tarballs may subsequently settle to the seafloor or attach to other particles 

or bodies in the sea. As residues of an oil spill disperse, marine mammals may be exposed via the 

waters that they inhabit, as well as via the prey they consume. For example, tarballs may be 

consumed by marine mammals and by other marine organisms that are eaten by marine mammals.

OSRA Modeling

The OSRA modeling results, which show the probabilities of a large spill (≥1,000 bbl) 

occurring in Federal offshore waters making contact with State offshore waters, are provided in 

Figure E-20. In general terms, coastal waters of the area may be contacted by many, frequent, 

small spills (≤1 bbl); few, infrequent, moderately-sized spills (>1 and <1,000 bbl); and a single large 

spill (≥1,000 bbl) as a result of a proposed lease sale. Pipelines pose the greatest risk of a large 

spill occurring in coastal waters compared with platforms and tankers. Spill estimates over a 50-year 

time period are indicated in Table 3-18. According to Table 3-18, the majority of estimated spills 

would be small (<10 bbl). The actual number of spills that may occur in the future could vary from 

the estimated number. A spill size group for ≥10,000 bbl was not included in Table 3-18 because 

the catastrophic Deepwater Horizon oil spill (4.9 MMbbl released from the well) was the only spill in 

this size range during 1996-2010 and such a spill is not reasonably foreseeable in the future; thus, 

limited conclusions can be made from a single data point. For more information on OSRA, refer to 

Chapter 3.2.1.4 (“Analysis of Offshore Spills ≥1,000 bbl”).

Depending on the timing of a spill’s occurrence in coastal waters, its impact and resulting 

cleanup activities may interrupt marine mammal migration, feeding, mating, and/or calving activities 

for extended periods (i.e., days, weeks, or months). Spills originating in or migrating through coastal 

waters of Florida may impact any marine mammal species inhabiting the area, including the West 

Indian manatee, which commonly inhabits Florida’s coastal waters. However, it is highly unlikely 
4-254 Gulf of Mexico Multisale EIS

that any spill occurring in Federal offshore waters would make contact with coastal waters in Florida 

(<0.5%) where manatees are commonly found. Aside from the acute impacts noted earlier, if marine 

mammals encounter an oil slick, the displacement of marine mammals to less suitable habitats from 

habitual feeding areas impacted by oil spills may increase vulnerability to predators, disease, or 

mortality from anthropogenic causes.

The likelihood that individuals of a marine mammal population may encounter an oil slick 

resulting from a single spill during a 50-year period is greater than that of a single individual 

encountering a slick during its lifetime. It is impossible to estimate precisely what marine mammal 

species, populations, or individuals would be impacted, to what magnitude, or in what numbers, 

since each species has unique distribution patterns in the GOM and because of difficulties attributed 

to estimating when and where oil spills would occur over a 50-year period.

Given the distribution of available leases and pipelines associated with a proposed lease 

sale and the distribution of marine mammals in the northern GOM, the fate of an oil spill must be 

considered relative to the region and period of exposure. Projected oil production is 

0.211-1.118 BBO and 0.547-4.424 Tcf of gas over 50 years. Chapter 3.2.1 details the persistence, 

spreading, and weathering process for offshore spills.

Although marine mammals may (or may not) avoid oil spills or slicks, it is highly unlikely that 

they are capable of avoiding spill residuals in their environment at some point in their lifetime. 

Consequently, the probability that a marine mammal is exposed to hydrocarbons resulting from a 

spill extends well after the oil spill has dispersed from its initial aggregated mass. Populations of 

marine mammals in the northern GOM would likely be exposed to residuals of spilled oil throughout 

their lifetime. Depending on where the actual spill occurs, the species of marine mammal, the 

distance of marine mammals in relation to the spill, and if the marine mammal accidentally ingests oil 

while feeding, impacts may be negligible to major. An example of a negligible impact would be if 

a group of oceanic bottlenose dolphins were traveling in an area where a reasonably foreseeable 

small accidental spill occurred at a well, but the group of bottlenose dolphins never encountered the 

oil and continued traveling. An example of a major impact would be if an individual Bryde’s whale 

(population estimate of 33 individuals) were to ingest oil while feeding and the impacts resulted in 

physical injury or mortality. Because the population estimate is so low for this species, this would 

diminish the continued viability of the population, including the annual rates of recruitment or 

survival. 

Spill-Response Activities 

Spill-response activities that may impact marine mammals include increased vessel traffic, 

the use of dispersants, and remediation activities (e.g., controlled burns, skimmers, boom, etc.). 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 of spilled oil. In addition, the large number 

of response vessels could place marine mammals at a greater risk of vessel collisions, which could 
Description of the Affected Environment and Impact Analysis 4-255

cause fatal injuries. Manatees are particularly vulnerable to vessel collisions that may result from 

increased vessel traffic. Vessel noise would also increase as a result of increased vessel activity 

and could result in behavioral changes in some individuals.

Spill-response activities could also include the application of dispersants to the affected area. 

Dispersants are designed to break oil on the water’s surface into minute droplets, which then break 

down in seawater. Essentially little is known about the impacts of oil dispersants on cetaceans, 

except that removing oil from the surface would reduce the risk of contact and render it less likely to 

adhere to skin, baleen plates, or other body surfaces (Neff, 1990). A laboratory experiment by Wise 

et al. (2014) found that chemical dispersants used during the Deepwater Horizon oil-spill response 

were cytotoxic to sperm whale cells and could lead to fibrosis and impaired organ function. 

However, it is difficult to determine how these exposures relate to the actual exposures in the GOM 

since there is no known accurate method to measure the amount of whale exposure to dispersants 

(Wise et al., 2014). The acute toxicity of most oil dispersant chemicals is considered to be low 

relative to the constituents and fractions of crude oil and refined products, and a study by Wells 

(1989) showed that the rate of biodegradation of dispersed oil is equal to or greater than that of 

undispersed oil. Varieties of aquatic organisms readily accumulate and metabolize surfactants from 

oil dispersants; however, metabolism of surfactants is thought to be rapid enough that there is little 

likelihood of food chain transfer from marine invertebrates and fish to predators, including marine 

mammals (Neff, 1990). Impacts from dispersants are unknown but may be irritants to tissues and 

sensitive membranes (NRC, 2005). One assumption concerning the use of dispersants is that the 

chemical dispersion of oil would considerably reduce the impacts to marine mammals, primarily by 

reducing their exposure to petroleum hydrocarbons (French-McCay, 2004; NRC, 2005). However, 

the impacts to marine mammals from chemical dispersants could include nonlethal injury (e.g., 

tissue irritation and inhalation), long-term exposure through bioaccumulation, and potential shifts in 

distribution from some habitats.

Some remediation activities that could impact marine mammals include the use of skimmers, 

booms, and controlled burns. Impacts from skimmers could be through capture and/or entrainment. 

Booming operations could potentially impact marine mammals, particularly manatees, as they are 

close to shore and known to explore and interact with objects in their environment (Hartman, 1979). 

Lines used to anchor booms are more likely than the boom itself to impact manatees, by 

entanglement. Controlled burns could impact marine mammals if they were in the burning oil; 

however, it is expected that animals would avoid the area once it is ignited. In both skimming and 

controlled burning activities, the use of trained observers is common and reduces the likelihood of 

impacts to marine mammals. Because of the low probability of marine mammals being in the vicinity 

of an OCS-related oil-spill response activity due to their wide-ranging behavior, impacts are 

expected to be negligible to moderate. An example of a negligible impact would be if a small 

group (5-8 individuals) of Atlantic spotted dolphins was traveling in an area where remediation 

activities are being conducted to control an oil spill, but the group of Atlantic spotted dolphins never 

encountered the remediation activities and continued traveling. An example of a moderate impact 

would be if a small group (5-8 individuals) of spinner dolphins (population estimate of 

11,441 individuals) encountered dispersants while traveling and experienced a nonlethal injury via
4-256 Gulf of Mexico Multisale EIS

inhalation at the water-surface interface. Although it may have a localized impact on that particular 

group of spinner dolphins, it would not diminish the continued viability of the population, including the 

annual rates of recruitment or survival.

Cumulative Impacts

The cumulative analysis considers past, present, and foreseeable future human and natural 

activities that may occur and adversely affect marine mammals in the same general area that may 

be affected by a proposed action.

The major impact-producing factors relative to a proposed action are described in Chapter 

4.9 (Protected Species) above in Table 4-13. Chapters providing supportive material for the marine 

mammals analysis include Chapters 4.9.1 (description of marine mammals), 3.1.2 (Exploration and 

Delineation), 3.1.3 (Offshore Development and Production), 3.1.4 (Transport), 3.1.5 (Discharges and 

Wastes), 3.1.9 (Noise), 3.1.7 (Coastal Infrastructure), 3.1.6 (Decommissioning and Removal 

Operations), and 3.2.1 (Oil Spills).

OCS Oil- and Gas-Related Impacts

The major potential impact-producing factors affecting marine mammals in the GOM as a 

result of cumulative past, present, and reasonably foreseeable OCS energy-related activities are 

described under the “Routine Activities” and “Accidental Events” sections above and include the 

following: decommissioning; operational discharges; G&G activities; noise; transportation; marine 

debris; and accidental oil spill and spill-response activities. The cumulative impact of these ongoing 

OCS energy-related activities on marine mammals is expected to result in a number of chronic and 

sporadic sublethal effects (i.e., behavioral effects and nonfatal exposure to or intake of OCS oil- and 

gas -related contaminants or discarded debris) due to the fact that these activities may stress and/or 

weaken individuals of a local group or population and may predispose them to infection from natural 

(e.g., bacteria) or anthropogenic (e.g., marine debris) sources.

As previously discussed in Chapter 4.9.1.2 (“Routine Activities”), the use of explosives is the 

preferred method for the severance of structures from their foundations in the GOM. Explosive 

structure removals put loud but temporary noise into the ocean, and these can occur in Federal or 

State waters. The shock wave and blast noise from explosions are of most concern to marine 

mammals. Depending on the intensity of the shock wave and size and depth of the animal, an 

animal can be injured or killed. Farther from the blast, an animal may suffer nonlethal physical 

impacts. Outside of these zones of death and physical injuries, marine mammals may experience 

hearing-related impacts with or without behavioral responses. A limited amount of information is 

available on the impacts of explosions on marine mammals (O’Keeffe and Young, 1984; Ketten, 

1998). However, BOEM (then BOEMRE) issued “Decommissioning Guidance for Wells and 

Platforms” (NTL 2010-G05), which specifies and references mitigation requirements in the current 

ESA and MMPA guidance and which should minimize the chance of a marine mammal being 

impacted from explosive severance activities. “Decommissioning Guidance for Wells and Platforms” 

(NTL 2010-G05) is discussed in Chapter 4.9.1.2 (“Routine Activities”).
Description of the Affected Environment and Impact Analysis 4-257

Industry noise sources include seismic operations, fixed platforms and drilling rigs, drilling 

ships, low-flying aircraft, vessel traffic, and explosive operations, particularly for structure removal. 

Chapter 3.1 describes the offshore infrastructure and activities (impact-producing factors) 

associated with a proposed lease sale. A discussion of all activities that are projected from past, 

present, and future lease sales during a 70-year activity period (2017-2086) can be found in 

Chapter 3.3. 

Accidental events related to a proposed action, as discussed above, have the potential to 

have adverse, impacts to marine mammal populations in the GOM.

Oil spills may cause chronic (long-term lethal or sublethal oil-related injuries) and acute (spillrelated deaths occurring during a spill) impacts on marine mammals. Long-term impacts include 

(1) decreases in prey availability and abundance because of increased mortality rates, (2) change in 

age-class population structure because certain year-classes were impacted more by oil, 

(3) decreased reproductive rate, and (4) increased rate of disease or neurological problems from 

exposure to oil (Harvey and Dahlheim, 1994). The impacts of cleanup activities are unknown, but 

increased human presence (e.g., vessels) could add to changes in marine mammal behavior and/or 

distribution, thereby additionally stressing animals, and perhaps making them more vulnerable to 

various physiologic and toxic impacts. However, there is no supporting evidence that marine 

mammal populations of the GOM are impacted by the cumulative OCS oil-and-gas related activities. 

Therefore, the incremental cumulative contribution of OCS- oil and gas-related activities is expected 

to have negligible to major impacts. 

Non-OCS Oil- and Gas-Related Impacts

Non-OCS energy-related activities that may affect marine mammal populations include 

pollution, marine debris, explosive severance of structures in non-OCS State waters as part of State 

oil- and gas-related activities, vessel traffic and related noise (e.g., from military operations, 

commercial shipping, and research vessels); commercial and recreational fishing (Chapters 4.10 

and 4.11), scientific research, diseases, UMEs, and natural phenomena. Specific types of impactproducing factors considered in this cumulative analysis include noise from numerous sources, 

pollution, ingestion and entanglement in non-OCS marine debris, and vessel strikes.

Pollution in the ocean comes from many point (e.g., non-OCS discharges, factories, 

wastewater treatment facilities) and nonpoint (e.g., drainage, precipitation, land runoff) sources, and 

the GOM is certainly no exception. The drainage of the Mississippi River results in massive 

amounts of chemicals and other pollutants being constantly discharged into the GOM. The zone of 

hypoxia on the Louisiana-Texas shelf is one of the largest areas of low oxygen in the world’s coastal 

waters (Murray, 1997) and does not support adequate food resources due to its low oxygen levels 

(refer to Chapter 3.3.2.12). Primarily, bottlenose dolphins and manatees are most at risk for 

nearshore pollution. Bottlenose dolphins have been reported having very high levels of 

contaminants, including heavy metals, in tissue samples (Borrell, 1993). Since other marine 

mammals are not commonly found in coastal waters, they are less likely to be impacted by 
4-258 Gulf of Mexico Multisale EIS

nearshore pollution. Prey species also affect the influence of pollution on marine mammals. 

Biomagnification in fish results in the generally higher contaminant levels in fish-eating marine 

mammals (Gray, 2002). Manatees are herbivores, but pollution and habitat degradation may impact 

the manatee. Manatees are exposed to herbicides by ingesting aquatic vegetation containing 

concentrations of these compounds (O’Shea et al., 1984). The propensity of manatees to aggregate 

at industrial and municipal outfalls also may expose them to high concentrations of contaminants 

(Stavros et al., 2008). Antifouling bottom paint on the hulls of boats has been linked to the release of 

contaminants (Schiff et al., 2004). For coastal dolphins and especially manatees that are very well 

known to frequent marinas and that scratch on the hulls of vessels, areas with high concentrations of 

vessels may have extremely polluted waters. However, there are non-OCS regulations that limit the 

discharge of pollutants in State waters (e.g., NPDES). Therefore, impacts to marine mammals from 

non-OCS pollutants would be negligible to minor. 

Ingestion of, or entanglement in, non-OCS marine debris is a global concern for marine 

organisms. Estimates indicate that approximately 6.4 million tons of marine litter is dumped in 

oceans every year, resulting in an estimated 13,000 pieces of litter per square kilometer of ocean 

(United Nations Environment Programme, 2005). There is general consensus that land-based 

sources are the dominant origin of marine debris, contributing up to 49 percent, with marine or 

undetermined sources contributing the remainder (Sheavly and Register, 2007). Plastic bags and 

small plastic fragments are the most commonly reported debris items in the digestive tracts of 

cetaceans and manatees (e.g., Barros and Odell, 1990; Tarpley and Marwitz, 1993; Laist, 1997); 

however, ingestion of net materials can also be fatal (Jacobsen et al., 2010). Plastics are very 

persistent, yet they are not immune to degradation. Microplastics, or microscopic plastic particles, 

may be ingested by a wide range of organisms, and there are indications that microplastics are 

propagated over trophic levels of the marine food web (Farrell and Nelson, 2013; Setälä et al., 

2014). Therefore, marine mammals may be ingesting plastic particles through consumption of 

various prey sources.

Entanglement in marine debris can cause decreased swimming ability, disruption in feeding, 

life-threatening injuries, and death. The debris items most often found entangling animals are net 

fragments and monofilament line from commercial and recreational fishing boats, as well as 

strapping bands and ropes from a variety of vessels. Impacts from non-OCS marine debris are 

expected to be negligible to major. An example of a negligible impact would be if small pieces of 

marine debris were ingested by a marine mammal species and then later passed through their 

digestive tract with no complications. An example of a major impact would be if a discarded 

monofilament fishing net were to cause physical injury or mortality to a marine mammal species with 

a low population estimate (e.g., Bryde’s whale).

Structure removals that take place in GOM State waters are under the jurisdiction of the 

COE. Impacts to marine mammals from these activities are similar to the impacts discussed in 

Chapter 4.9.1.2 (“OCS Oil- and Gas-Related Impacts”) and may potentially include injury or death 

from shockwave depending on the intensity of the shock wave and size and depth of the animal; 

nonlethal physical effects; and hearing-related effects with or without behavioral responses.
Description of the Affected Environment and Impact Analysis 4-259

Numerous sources of aircraft fly over the coastal and offshore areas. The air space over the 

GOM is used extensively by DOD for conducting various air-to-air and air-to-surface operations. 

Eleven military warning areas and six water test areas are located within the GOM, as stated in NTL 

2009-G06, “Military Warning and Water Test Areas” (Figure 2-7). Additional activities, including 

vessel operations and ordnance detonation, also may impact marine mammals. Subject to Federal 

Aviation Administration guidelines, private and commercial air traffic further traverse these areas and 

have the potential to cause impacts to marine mammals.

The GOM has very little fishery interaction with marine mammals compared with other areas. 

However, marine mammals can be injured or killed by commercial fishing gear. Mammals can either 

get caught on longline hooks or can be entrained into a net by a shrimp boat or groundfish vessel. 

There is also the chance of entanglement by lines from crab traps to buoys. Gillnets, which have 

now been banned in many places around the GOM, have been reported to take marine mammals. 

However, recent reports of these impacts are uncommon. Depending on the type of fishing gear 

and the number of marine mammals affected by the interaction with the fishing gear, impacts would 

be negligible to major. An example of a negligible impact would be if a marine mammal species 

observed fishing activities, made no behavior change, and ultimately had no interaction with the 

fishing gear or activities. An example of a major impact would be if a commercial fishing net were to 

cause physical injury or mortality to a marine mammal species with a low population estimate (e.g., 

killer whale).

All manner of commercial shipping vessels, commercial fishing vessels, military ships, 

research ships, recreational craft, and others are always present in the GOM and increases the 

possibility of vessel collisions between vessels and marine mammals. Slow-moving marine 

mammals or those that spend extended periods of time at the surface might be expected to be the 

most vulnerable (Vanderlaan and Taggert, 2007). In 2014, approximately 85 percent of humancaused manatee mortalities in Florida were attributed to collisions with watercraft (State of Florida, 

Fish and Wildlife Conservation Commission, 2015c). Noise from various non-OCS vessels could 

interfere with marine mammal communication either by masking important sounds from conspecifics, 

masking sounds from predators, or by forcing animals to alter their vocalizations (Tyack, 2008).

Some factions of the boating public, mainly recreational fishermen and boaters, create 

adverse impacts by paying too much attention to marine mammals. Reports of harassment, 

inappropriate feeding, and even attempting to swim with marine mammals are common. Dolphins 

have been injured and killed after becoming accustomed to being fed by humans. Animals become 

sick from eating the “food” that people throw. Very close approaches by boats are likely major 

causes of stress in marine mammals, as is chasing and following.

Scientific research can impact marine mammal species. Numerous marine mammal 

research cruises have been conducted, and permitted activities have included tagging and biopsy 

sampling. The U.S. protocols are always in place to keep the mammals safe, but some of the 

research techniques do involve harassment and possible stress to the animal. Scientific seismic 

studies often use the same tools and techniques as industry seismic work, which could have the 
4-260 Gulf of Mexico Multisale EIS

same impacts to marine mammals. Scientific groundfish or shrimp cruises can entrap a dolphin in a 

net just as commercial fisheries can. In 2011, a scientific cruise that was associated with NRDA 

killed six dolphins while sampling fish with nets. Scientific aerial surveys are also periodically 

conducted in the GOM, and aircraft can startle marine mammals. Circling pods for identification may 

stress multiple individuals in a pod. Such marking techniques as freeze branding were used in the 

past to do mark-recapture studies. This required the live capture and branding of dolphins. Both the 

Navy and the public-display industry took bottlenose dolphins from the GOM in years past. A 

moratorium on live captures has been in effect for several years, as captive breeding programs have 

become successful enough to provide dolphins for aquariums and zoos.

Occasionally, numbers of marine mammals strand, either alive or already dead. Die-offs 

happen infrequently but can seriously deplete small, discrete stocks. The causes of die offs are not 

always well known and vary by event. Some appear to be triggered by natural events (i.e., 

unusually cold weather) but others are suspected to at least be indirectly caused by pollution of 

various contaminants. Exposure to certain compounds may weaken the natural immunity of marine 

mammals and make them susceptible to viruses and diseases that would normally not affect them. 

Certain viruses, such as morbilliviruses, which affect the lungs and brain in cetaceans, are being 

observed more frequently than in the past (USDOC, NMFS, 2013). A red-tide event that began in 

southwest Florida in late September 2012 claimed the highest number of red-tide-related manatee 

deaths in a single calendar year on record (State of Florida, Fish and Wildlife Conservation 

Commission, 2015c). The NMFS may declare a large die-off to be an UME, which 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” (USDOC, NMFS, 2015e). The causes for more than 

20 UMEs that have been declared by NMFS in the GOM region since 1991 have either been due to 

infectious diseases or biotoxins, or were declared undetermined. However, some UMEs in the GOM 

are still ongoing and may be subject to change as new information from these strandings becomes 

available. The most recent information for UMEs in the GOM can be found on the NMFS website 

(USDOC, NMFS, 2015f).

Impacts from climate change to marine mammals have become a concern, and responses 

both at the individual and population level of marine mammal species to climate change are poorly 

understood (Evans and Bjørge, 2013). Making predictions about future impacts becomes even more 

speculative. In the last 15 years, a number of marine mammal scientists have attempted to do this 

(Tynan and DeMaster, 1997; International Whaling Commission, 1997; Würsig et al., 2002; 

Learmonth et al., 2006; Simmonds and Isaac, 2007; Huntington and Moore, 2008; Kovacs and 

Lyderson, 2008; Laidre et al., 2008; International Whaling Commission, 2009; MacLeod, 2009; 

Evans et al., 2010; Kaschner et al., 2011). Some of major hypothesized impacts to marine

mammals from climate change are changes in water temperatures, which may result in distribution 

changes, changes to physical habitat, changes to the food web, thermal Intolerance (e.g. heat 

stress), and susceptibility to increased diseases and contaminants (Evans and Bjørge, 2013). 

Lastly, tropical storms and hurricanes are normal occurrences in the GOM and along the Gulf Coast. 

Generally, the impacts have been localized and infrequent. However, the GOM has been hit 

extremely hard by very powerful hurricanes. Few areas of the coast have not suffered some 
Description of the Affected Environment and Impact Analysis 4-261

damage in 2004 and 2005, and activities in the GOM have also been severely impacted. In 2004, 

Hurricane Ivan took a large toll on oil and gas structures and operations in the GOM and caused 

widespread damage to the Alabama-Florida Panhandle coast. In 2005, Hurricanes Katrina, Rita, 

and Wilma reached Category 5 strength in the GOM, and these hurricanes were followed in 2008 by 

Hurricane Gustav and by Hurricane Isaac in 2012. These storms caused damage to all five of the 

Gulf Coast States and damage to structures and operations both offshore and onshore. The actual 

impacts of these storms on marine mammals in the GOM have not yet been determined and, for the 

most part, may remain very difficult to quantify.

The impacts of such natural disasters on marine mammal populations are poorly understood 

and difficult to assess due to the limited predictability of storm occurrence, course, strength, and 

location of impact. Some immediate and direct impacts of hurricanes on marine mammals have 

been documented, such as the temporary displacement or stranding of individuals (e.g., dugongs 

[Dugong dugon; Marsh, 1989]; pygmy killer whales [Feresa attenuata; Mignucci-Giannoni et al., 

1999]; and bottlenose dolphins [Tursiops truncatus; Rosel and Watts, 2008]). Under some 

circumstances, hurricanes can cause massive mortalities of fish and destruction of their habitats in 

coastal and estuarine ecosystems (Tabb and Jones, 1962) causing dolphins to be temporarily 

displaced when seeking new foraging areas.

Evaluation of long-term impacts of severe storms to marine mammals requires multi-year 

studies to be in place prior to a disaster to adequately measure the impacts (Smith et al., 2013), in 

which there are few. Langtimm et al. (2006) found that the destruction of habitat in important 

foraging areas following severe tropical systems may have indirectly increased mortality in Florida 

manatees (Trichechus manatus latirostris) (Langtimm et al., 2006). However, some evaluations of 

long-term impacts to coastal marine mammals have documented their resilience and adaptability. 

Miller et al. (2010) investigated the impacts of Hurricane Katrina on bottlenose dolphin reproduction 

in the Mississippi Sound area. The study reported an increase in reproduction, which was attributed, 

in part, to a potential increase in prey abundance in the area following a widespread decrease in 

annual fisheries landings in the area during the year following the storm (Miller et al., 2010). A 

similar study in the same area by Smith et al. (2013) also found that bottlenose dolphin foraging 

activity increased significantly following the passage of Hurricane Katrina, suggesting that there may 

have been an increase in feeding opportunity, prey abundance, and/or a need for increased food 

consumption likely attributed to the same decrease in annual fisheries landings. Cumulative 

incremental impacts to marine mammals, when taking into consideration the potential impacts of the 

Deepwater Horizon explosion, oil spill, and response, non-OCS oil- and gas-related factors, and the 

minimization of OCS oil- and gas-related impacts through lease stipulations and regulations, would 

be expected to be negligible as a result of a proposed lease sale. This is because marine 

mammals are wide-ranging and population-level impacts are not anticipated. However, cumulative 

impacts could have a major impact on particular marine mammal species with a low population 

level, dependent upon the level of impact and number of individuals affected by it (e.g., if an impact 

to a Bryde’s whale [population estimate of 33 individuals] were to result in a mortality, it would

diminish the continued viability of the population including the annual rates of recruitment or 

survival). 
4-262 Gulf of Mexico Multisale EIS

Incomplete or Unavailable Information

BOEM has identified incomplete information regarding impacts of the Deepwater Horizon

explosion, oil spill, and response on marine mammals in the GOM. This incomplete information may 

be relevant to the evaluation of adverse impacts because it could provide changes in the baseline 

environmental conditions for marine mammals in the affected environment from the Deepwater 

Horizon oil spill and response, exacerbating any impacts from a proposed action. Much of these 

data are being developed through the NRDA process, which may take years to complete. Even after 

it is available, the impacts of the oil spill may be difficult or impossible to discern from other factors.

The NMFS declared an UME for cetaceans (whales and dolphins) in the northern Gulf of 

Mexico in February 2010, before the Deepwater Horizon explosion, oil spill, and response. In 

addition to investigating all other potential causes, scientists are investigating what role Brucella may 

have played in the UME, which is still in effect as of publication of this Multisale EIS. Brucella spp. 

refers to a genus of bacteria that infect many terrestrial and aquatic vertebrates around the world. 

The disease, called brucellosis, is best known for its role in causing abortion in domestic livestock 

and undulant fever in people. Updated information on Brucella and its role in this UME can be found 

on NMFS’s website (USDOC, NMFS, 2015e).

It is 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. According to the NMFS website 

referenced above, which is the only publicly available source of information at this time on the UME, 

evidence of the UME was first documented by the NMFS as early as February 2010, nearly 

2 months prior to the Deepwater Horizon explosion and oil spill. The NMFS has also documented 

an additional 12 UMEs that have been previously declared in the GOM for cetaceans (an additional 

7 specific to manatees only) since 1991. However, studies published from the NRDA process 

evaluating the possible impacts of the Deepwater Horizon explosion, oil spill, and response on 

bottlenose dolphins exposed to oiling have shown overall poor health and prevalence of poor body 

condition, disease, and abnormalities as compared with bottlenose dolphins in the Gulf of Mexico 

that were not exposed to oiling (Schwacke et al., 2013; Venn-Watson et al., 2015). Bacterial 

pneumonia was also identified from dolphins before and during the UME but it was detected more in 

the UME dolphins (Venn-Watson et al., 2015). Continued research would provide a better 

understanding about the UME, which is still under investigation as of the publication of this Multisale 

EIS. While this information may ultimately be useful in expanding the available knowledge on 

baseline environmental conditions following the Deepwater Horizon explosion, oil spill, and 

response, it remains difficult to draw specific conclusions regarding the current overall bottlenose 

dolphin population in the GOM. 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.

Even with recent publications, such as the Venn-Watson et al. (2015) marine mammal study, 

the best available information on impacts to GOM marine resources does not yet provide a complete 

understanding of the impacts of the oil spill and active response/cleanup activities from the 
Description of the Affected Environment and Impact Analysis 4-263

Deepwater Horizon explosion and oil spill on marine resources as a whole in the GOM and whether 

these impacts reach population-level impacts. Relevant data on the status of marine mammal 

populations after the UME and 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. For example, even 20 years after the 

Exxon Valdez spill, the long-term impacts to marine mammal populations are still being investigated 

(Matkin et al., 2008). Therefore, it is not possible for BOEM to obtain this information within the 

timeline contemplated for analysis in this Multisale EIS, regardless of the cost or resources needed. 

Unavailable information, such as the anthropogenic impacts following an oil-spill response and the 

population variation due to naturally occurring events such as hurricanes and heightened stranding 

numbers, provides challenges in understanding the baseline conditions and changes within marine 

mammal populations. However, 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 marine mammals using studies investigating evidence of oil and 

impacts stemming from exposure to oil (Schwacke et al., 2013; Venn-Watson et al., 2015). Although 

additional information may be relevant to the evaluation of impacts to marine mammals, BOEM has 

determined that the incomplete information is not essential to a reasoned choice among alternatives 

because none of the sources reveal reasonably foreseeable significant adverse impacts to marine 

mammals not otherwise considered in this Multisale EIS (e.g., the assumption that released oil and 

dispersants could reduce fitness of individuals). In addition, non-OCS energy-related factors would 

continue to occur in the GOM irrespective of a proposed action.

Nevertheless, there are existing leases in the GOM with either ongoing or the potential for 

exploration, drilling, and production activities. In addition, non-OCS oil- and gas-related activities 

would continue to occur in the GOM irrespective of a proposed action (e.g., fishing, military activities, 

and scientific research).

4.9.1.2.1 Alternatives A, B, C, and D

With respect to marine mammal species, the effects associated with selection of any of the 

alternatives would be equivalent because of the diversity and distribution of marine mammal species 

throughout the potential areas of interest. The preceding analyses assumed a wide distribution of 

species and considered impacts to marine mammal species occurring in a wide range of habitats 

across all planning areas. While the WPA is a smaller area with less projected activity than is 

proposed for the CPA/EPA (refer to Chapter 3), marine mammal species are widely distributed 

throughout the planning areas. As such, activities isolated to specific planning areas pose similar 

potential impacts to individuals as do activities occurring in all planning areas. Therefore, a similar 

mix of species would be exposed to the analyzed impact-producing factors, regardless of the 

specific action alternative selected. The activities proposed under Alternatives A, B, C, and D could 

directly impact marine mammal species within the GOM and contribute incrementally to the 

cumulative effects on these species. Although there would always be some level of incomplete 

information on the impacts from routine activities under a proposed action on marine mammals, 

there is credible scientific information, applied using acceptable scientific methodologies, to support 
4-264 Gulf of Mexico Multisale EIS

the conclusion that any realized impacts would be sublethal in nature and not in themselves rise to 

the level of reasonably foreseeable significant adverse (population-level) impacts. Also, routine 

activities would be ongoing in the proposed action area as a result of active leases and related 

activities. There are no data to suggest that routine activities from the previous OCS Program are 

significantly impacting marine mammal populations. The net result of any disturbance would 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). Accidental events that involve large spills, particularly those continuing to flow 

fresh hydrocarbons into oceanic and/or outer shelf waters for extended periods (i.e., days, weeks, or 

months), pose an increased likelihood of impacting marine mammal populations inhabiting these 

waters.

The effects of a proposed action, when viewed in light of the impacts associated with other 

past, present, and reasonably foreseeable future activities, may result in greater impacts to marine 

mammals than before the Deepwater Horizon explosion, oil spill, and response; however, the 

magnitude of those impacts cannot yet be determined. Nonetheless, 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-BSEEG01 (“Marine Trash and Debris Awareness and Elimination”), as well as the limited scope, timing, 

and geographic location of a proposed lease sale, would result in negligible impacts 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 for injury from seismic operations to marine mammals. These mitigations include onboard 

observers, airgun shut-downs for whales in the exclusion zone, ramp-up procedures, and the use of 

a minimum sound source. The Protected Species Stipulation, if applied, requires compliance with 

any terms and conditions from past and future biological opinions from the NMFS and FWS.

Cumulative impacts on marine mammals are expected to result in a number of chronic and 

sporadic sublethal impacts (i.e., behavioral effects and nonfatal exposure to or intake of OCS 

oil- and gas-related or non-OCS oil- and gas-related contaminants or discarded debris) that may 

stress and/or weaken individuals of a local group or population and predispose them to infection 

from natural or anthropogenic sources (Harvey and Dahlheim, 1994). Disturbance (i.e., noise from 

vessel traffic and drilling operations) and/or exposure to sublethal levels of toxins and anthropogenic 

contaminants may stress animals, weaken their immune systems, and make them more vulnerable 

to parasites and diseases that normally would not be fatal (Harvey and Dahlheim, 1994). There is 

potential for impacts from routine activities or accidental events to be greater on individuals or 

populations already impacted by other OCS oil- and gas-related or non-OCS oil- and gas-related 

impact-producing factors. However, within the GOM, there is a long-standing and well-developed 

OCS Program (more than 50 years) and there are no data to suggest that activities from the 

previous OCS Program are significantly impacting marine mammal populations.
Description of the Affected Environment and Impact Analysis 4-265

The incremental contribution of a proposed lease sale (Alternatives A, B, C, or D) to 

cumulative impacts to marine mammal populations, depending upon the affected species and their 

respective population estimate, even when taking into consideration the potential impacts of the 

Deepwater Horizon explosion, oil spill, and response; non-OCS oil- or gas-related factors; and the 

minimization of OCS oil- or gas-related impacts through lease stipulations and regulations, would be 

expected to be negligible to moderate as a result of a proposed action (Alternatives A, B, C, or D) 

and the period analyzed.

4.9.1.2.2 Alternative E—No Action

If selected, Alternative E would not contribute to impacts on marine mammal species within 

the GOM. However, cumulatively, the impacts resulting from the routine activities and accidental 

events and the cumulative impacts from previously permitted activities and prior lease sales would 

continue and be unchanged from the conclusion reached for the action alternatives because of 

existing oil and gas activities. Therefore, the significance of impact-producing factors on marine 

mammals would be the same for Alternative E as the impacts discussed in Chapter 4.9.1.2 for 

previously permitted activities and prior lease sales.

4.9.2 Sea Turtles

Five sea turtles are known to inhabit the waters of the GOM (Pritchard, 1997): the 

loggerhead (Caretta caretta), Kemp’s ridley (Lepidochelys kempii), green (Chelonia mydas), 

leatherback (Dermochelys coriacea), and hawksbill (Eretmochelys imbricata). These five species 

are all highly migratory with individual animals migrating into nearshore waters as well as other 

areas of the Gulf of Mexico, North Atlantic Ocean, and the Caribbean Sea. All of the sea turtles 

species found in the GOM are protected under the Endangered Species Act of 1973. The FWS and 

NMFS share Federal jurisdiction for sea turtles. The FWS has responsibility for sea turtles (i.e., 

eggs, hatchlings, and nesting turtles) on the nesting beaches, and the NMFS has jurisdiction for sea 

turtles in the marine environment. Refer to Chapter 4.9 above for additional information. The 

approach of this analysis is to focus on the potential impact-producing factors from OCS oil- and 

gas-related routine activities (i.e., exploration, development, and production), as well as reasonably 

foreseeable accidental events and cumulative impacts, and to define impact-level measures for each 

impact-producing factor under a proposed action (refer to Table 4-13 in Chapter 4.9).

4.9.2.1 Description of the Affected Environment

All five species of sea turtles found in the GOM have been federally listed as endangered or 

threatened since the 1970’s. Information on individual species is discussed in the subsections below 

this general introduction. Information relevant to all five species, such as status reviews and nesting, 

are discussed here.

After reviewing all of the best scientific and publicly/commercially available information, the 

NMFS recommended that the current listing classification for each of the five sea turtle species 

remain unchanged in the GOM. In 2009, the NMFS completed a status review of loggerhead sea 
4-266 Gulf of Mexico Multisale EIS

turtles, and on September 22, 2011, the NMFS issued the final rule to list nine Distinct Population 

Segments (DPSs) of loggerhead sea turtles under the ESA and designated the GOM under the 

Northwest Atlantic Ocean DPS (Federal Register, 2011b). The Kemp’s ridley 5-year review was 

completed in July 2015 and the status has not changed (USDOC, NMFS and USDOI, FWS, 2015). 

In 2015, the NMFS completed a status review of green sea turtles, and although a proposed rule 

(Federal Register, 2015g) to designate green sea turtles as the North Atlantic DPS in the GOM was 

extended on August 26, 2015, the threatened status still remains. In 2013, the 5-year reviews for 

leatherback and hawksbill sea turtles were updated and the status has not changed (USDOC, NMFS 

and USDOI, FWS, 2013a and 2013b).

Nesting on the U.S. Gulf Coast has been documented for the five species of sea turtles; 

loggerheads and Kemp’s ridleys are the most common, followed by green sea turtles, and finally 

leatherback and hawksbill sea turtles, which rarely nest in the GOM (USDOC, NMFS and USDOI, 

FWS, 2007a-c, 2013a, and 2013b). While nesting female sea turtles can provide a useful index of 

specific species’ population size by looking at trends in the number of crawls, estimating clutch size, 

hatchlings, etc.; there are still data gaps to accurately assess overall population trends (NRC, 

2010b). An example of why population estimates are difficult is that the reported status and trends 

are variable for subpopulations and nesting aggregations. Data can be found for sea turtle nesting 

through different websites, including the National Park Service who has data for Texas (USDOI, 

NPS, 2016), Alabama’s Sea Turtle Conservation Program (Share the Beach, 2015), and the State of 

Florida, Fish and Wildlife Conservation Commission’s websites (State of Florida, Fish and Wildlife 

Conservation Commission, 2016a).

Although the use of turtle excluding devices has lessened interactions, fisheries impacts 

remain as the biggest threat to sea turtles (Lewison et al., 2013). Additionally, gas embolisms or 

decompression sickness has been recently observed in sea turtles caught as bycatch similar to that 

observed in postmortem humans that were autopsied, for example, following scuba diving accidents 

(Garcia-Parraga et al., 2014). Natural phenomenon, such as tropical storms and hurricanes, occur 

in the GOM and may impact nesting beaches (Dewald and Pike, 2013), depending on timing, size, 

and location of the storm. Storm impacts to nesting activity can be difficult to assess, but beach 

erosion has been shown to be one of the major factors affecting turtle hatchling success (Brost et al., 

2015). Within the planning areas, offshore species and the offshore habitat are not expected to be 

severely affected in the long term by natural events.

The Sea Turtle Stranding and Salvage Network monitors and investigates sea turtle 

strandings. The NMFS provides stranding data for the Gulf of Mexico (i.e., Texas, Louisiana, 

Mississippi, and Alabama) through its Office of Protected Resources site. These data are updated 

when the NMFS has the complete dataset from the Sea Turtle Stranding and Salvage Network. 

Because this can change at any time, BOEM refers the reader to the NMFS’s website (USDOC, 

NMFS, 2015g). Florida is not included in the NMFS’s Gulf of Mexico stranding data; however, 

Florida-specific stranding data can be found on the State of Florida, Fish and Wildlife Conservation 

Commission’s Florida Sea Turtle Stranding and Salvage Network website (State of Florida, Fish and 

Wildlife Conservation Commission, 2016b). There are many reasons, both natural and human
Description of the Affected Environment and Impact Analysis 4-267

caused, for the strandings in the northern GOM (USDOC, NMFS, 2015g). Looking at the NMFS’s 

2011-2013 data, stranding events, primarily in Mississippi, have included all five listed species. The 

majority of these turtles have been endangered Kemp's ridleys, loggerhead, and green turtles. 

However, stranding data are not indicative of population status because there are too many 

uncertainties associated with those data (Epperly et al., 1996; Nero et al., 2013).

Niedeoroda et al. (2014) modeled relative environmental sensitivity to BOEM-regulated OCS 

oil- and gas-related activities for nine OCS regions. Sea turtles selected as representative species 

for the model in the GOM included green, hawksbill, and Kemp’s ridley sea turtles; loggerheads 

were used in the southeast OCS for marine species’ impact sensitivity (i.e., vulnerability and 

resilience). Niedeoroda et al. (2014) also modeled offshore and shoreline habitat sensitivity. 

Overall, the eastern GOM and southeast U.S. continental shelf had the highest relative 

environmental sensitivity of the nine OCS regions, although loggerhead sensitivity ranked lower than 

the others out of the top species, with the 10 highest averages. Hawksbills in the GOM ranked 

slightly lower than the loggerhead in the southeast OCS. Live hard bottoms ranked second among 

the 25 environmentally sensitive habitats, and open water and Sargassum also ranked relatively 

high on the list. This model was based on species and habitat parameters that were used, and 

scoring was difficult due to behavior considerations and overall lack of environmental data 

(Niedeoroda et al., 2014).

Loggerhead Sea Turtle

The loggerhead sea turtle was listed as threatened on July 28, 1978 (Federal Register, 

1978). It is still considered threatened under the reclassification as the Northwest Atlantic Ocean 

DPS in the GOM (Federal Register, 2011b). Loggerhead turtles have been primarily sighted in 

waters over the continental shelf, although many surface sightings of this species have also been 

made over the outer slope beyond the 1,000-m (3,281-ft) isobath. Additionally, Van Houtan and 

Halley (2011) modeled oceanographic processes in relation to loggerhead regional population 

dynamics and found that they are strongly correlated; therefore, they should be considered in 

baseline conditions. Sightings of loggerheads in waters over the continental slope suggest that they 

may be in transit through these waters to distant foraging sites or while seeking warmer waters 

during the winter. Although loggerheads are widely distributed during both summer and winter, their 

abundance in surface waters over the slope was greater during winter than in summer (Mullin and 

Hoggard, 2000). Adult loggerheads are known to make extensive migrations between foraging 

areas and nesting beaches. During nonnesting years, adult females from U.S. beaches are 

distributed in waters off the eastern U.S. and throughout the Gulf of Mexico, Bahamas, Greater 

Antilles, and Yucatán (Conant et al., 2009).

Major nesting areas include the coastal islands of Georgia, South Carolina, and North 

Carolina, Florida’s Atlantic coasts. In the GOM, major nesting areas include some coastal beaches 

in Mississippi, Alabama, and Florida. In the western Atlantic, most loggerhead sea turtles nest in the 

geographic area ranging from North Carolina to the Florida Panhandle. Reproductive adult females 

return to their original hatching site to nest, preventing recolonization with turtles from other nesting 
4-268 Gulf of Mexico Multisale EIS

beaches. The southeastern U.S. nesting aggregation, which is mainly in the Atlantic, is of great 

importance on a global scale and is second in size only to the nesting aggregation on islands in the 

Arabian Sea off Oman (Ross, 1979; Ehrhart, 1989; USDOC, NMFS and USDOI, FWS, 2007b). 

Nesting data trends are declining in this species (Federal Register, 2011b; Witherington et al., 2009; 

Lamont et al., 2012). Five recovery units have been identified; three that are relevant are Peninsular 

Florida, Dry Tortugas, and the northern GOM. According to Ehrhart et al. (2003), the peninsular 

Florida Recovery Unit represents approximately 87 percent of all nesting effort in the Northwest 

Atlantic Ocean DPS. Atlantic loggerhead sea turtles concentrate their nesting in the north and south 

temperate zones and subtropics, and they generally do not nest in tropical areas (Magnuson et al., 

1990; USDOC, NMFS and USDOI, FWS, 2007b).

Developmental habitat for small juveniles is in the open ocean. Offshore, they reside for 

months in the oceanic zone in Sargassum floats, generally along the Loop Current and the west 

coast of Florida. Refer to Chapter 4.5 (Sargassum and Associated Communities) for additional 

information on pelagic waters. Somewhere between 7 and 12 years old, oceanic juveniles migrate 

to nearshore coastal areas to mature into adults. These nearshore waters become important 

foraging and migratory habitat for juveniles and adults. Juveniles may also spend time in bays, 

sounds, and estuaries (Epperly et al., 2007). Benthic immature loggerheads have been found from 

Cape Cod, Massachusetts, to southern Texas (USDOC, NMFS and USDOI, FWS, 2007d). Large 

benthic immature loggerheads (28-36 in; 70-91 cm) represent a larger proportion of the strandings 

and in-water captures along the south and western coasts of Florida as compared with the rest of 

the coast. Benthic immature loggerheads foraging in northeastern U.S. waters are known to migrate 

southward in the fall as water temperatures cool (Epperly et al., 1995; Morreale and Standora, 1999) 

and migrate northward in spring. Juveniles are omnivorous and forage on crabs, mollusks, jellyfish, 

and vegetation at or near the surface (Dodd, 1988). Subadult and adult loggerheads are primarily 

coastal and typically prey on benthic invertebrates such as mollusks and decapod crustaceans in

hard bottom habitats. McClellan and Read (2007) found that the shift from oceanic to neritic (i.e. 

coastal) waters is complex and reversible; some move into coastal waters and then return to open 

ocean.

Loggerheads mate in late March through early June in the southeastern U.S. Females 

emerge from the surf, excavate a nest cavity in the sand, and deposit a mean clutch (number of 

eggs per nest) size of 100-126 eggs (USDOC, NMFS, 2013). Individual females nest multiple times 

during a nesting season, with a mean of 4.1 nests/nesting individual (Murphy and Hopkins, 1984). 

Nesting migrations for an individual female loggerhead are usually on an interval of 2-3 years but 

can vary from 1 to 7 years (Dodd, 1988). Loggerhead sea turtles originating from the western 

Atlantic nesting aggregations are believed to lead a pelagic existence in the North Atlantic gyre for 

as long as 7-12 years, but there is some variation in habitat use by individuals at all life stages. 

Stranding records indicate that, when pelagic immature loggerheads reach a 16- to 24-in (40- to 

60-cm) straight-line carapace length, they begin to recruit to coastal inshore and nearshore waters of 

the continental shelf throughout the U.S. Atlantic and GOM. Bjorndal et al. (2013) combined 

datasets over a large spatial scale (range of 9-33°N. latitude) to examine northwest Atlantic 

loggerhead growth rates and found that there was a decline with increasing body size. Their study 
Description of the Affected Environment and Impact Analysis 4-269

indicated that latitude may be a major factor for smaller turtles (<2.6 ft; 80 cm) and that loggerheads 

may grow more rapidly in waters south of the U.S., noting that more data are needed for those 

waters to determine growth rates (Bjorndal et al., 2013).

Several recent reports are available concerning GOM loggerheads’ nesting habitats and 

movements (Hart et al., 2013a), post-nesting behavior (Foley et al., 2013), foraging sites (Foley 

et al., 2014; Tucker 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. 

Lamont et al. (2015) also published a report on the importance of the GOM for different life stages of 

the Northwest Atlantic Ocean DPS. Lamont et al. (2015) suggested that the loss of individual 

habitats could have long-term consequences to population recovery by affecting several life stages. 

Additional relevant information can be found in Chapter 4.3.2 (Coastal Barrier Beaches and 

Associated Dunes).

Ongoing threats to the western Atlantic loggerhead populations include incidental takes from 

dredging, commercial trawling (Epperly et al., 2002), longline fisheries (Lewison et al., 2004), and 

gillnet fisheries; loss or degradation of nesting habitat from storms (Brost et al., 2015) or coastal 

development and beach armoring; disorientation of hatchlings by beachfront lighting; nest predation 

by native and nonnative predators (Brost et al., 2015); degradation of foraging habitat; marine 

pollution and debris; watercraft strikes; and disease (USDOC, NMFS and USDOI, FWS, 2007b).

Kemp’s Ridley Sea Turtle

The Kemp’s ridley sea turtle was listed as endangered on December 2, 1970 (Federal 

Register, 1970b). On September 22, 2011, the Final Bi-National (Mexico and U.S.) recovery plan for 

Kemp’s ridleys was released. The 5-year review for Kemp’s ridleys was released on August 21, 

2015, and the classification did not change. This species was given higher recovery priority from the 

NMFS due to the potential for future extinction; while priority under the FWS remained the same 

(USDOC, NMFS and USDOI, FWS, 2015). Internationally, the Kemp’s ridley sea turtle is considered 

the most endangered sea turtle throughout its range.

Kemp’s ridleys have a restricted distribution through all its life stages relative to other sea 

turtle species. Data suggest that Kemp’s ridley turtles are found mainly in coastal areas of the GOM 

and the northwestern Atlantic Ocean. Sea-water temperature plays an important role in the 

distribution of this species (Ogren, 1989; Renaud, 1995; Renaud and Williams, 2005). The 

nearshore waters of the GOM are believed to provide important developmental habitat for juvenile 

Kemp’s ridley and loggerhead sea turtles. Ogren (1989) suggests that the Gulf Coast, from Port 

Aransas, Texas, through Cedar Key, Florida, represents the primary habitat for subadult Kemp’s 

ridleys in the northern GOM. Juvenile/subadult Kemp's ridleys have been found along the Eastern 

Seaboard of the U.S. (Epperly et al., 2007) and in the GOM. Atlantic juveniles/subadults travel 

northward with spring warming to feed in the productive, coastal waters of Georgia through New 

England, returning southward with the onset of winter to escape the cold (Ogren, 1989; USDOC, 

NMFS and USDOI, FWS, 2015).
4-270 Gulf of Mexico Multisale EIS

Kemp’s ridleys nest in daytime aggregations (April into July), known as arribadas, primarily at 

Rancho Nuevo, a stretch of beach in Mexico, Tamaulipas State (USDOC, NMFS and USDOI, FWS, 

2015). Remigration of females to the nesting beach varies from annually to every 4 years, with a 

mean of 2 years (Turtle Expert Working Group, 1998). The mean clutch size for Kemp's ridleys is 

100 eggs per nest, with an average of 2.5 nests per female per season. According to the 2011 

bi-national recovery plan, nests in and surrounding Rancho Nuevo exceeded 20,000, thereby 

representing 8,000 females for 2009 (Secretariat of Environment & Natural Resources et al., 2011). 

Kemp’s ridley sea turtle nests have increased in recent years along the South Padre Island National 

Seashore in Texas (USDOI, NPS, 2016).

In the GOM, juvenile/subadult Kemp’s ridleys occupy shallow, coastal regions. Little is 

known of the movements of the post-hatching, planktonic stage within the GOM, although model 

predictions suggest that it is mainly in waters offshore of Tamaulipas, Mexico (Putman et al, 2013). 

Studies have shown the post-hatchling pelagic stage varies from 1 to 4 years, and the benthic 

immature stage lasts 7-9 years (Schmid and Witzell, 1997). Benthic immature turtles with an 8- to 

24-in (20- to 60-cm) straight-line carapace length are found in nearshore coastal waters including 

estuaries of the GOM and the Atlantic, although adult-sized individuals sometimes are found on the 

Eastern Seaboard of the U.S. The post-pelagic stages are commonly found dwelling over crab-rich 

sandy or muddy bottoms. Juveniles frequent bays, coastal lagoons, and river mouths. Adults of this 

species are usually confined to the GOM, although adult-sized individuals sometimes are found on 

the Eastern Seaboard of the U.S. The Turtle Expert Working Group (1998) estimates age at 

maturity to range from 7 to 15 years.

Stomach contents of Kemp’s ridleys along the lower Texas coast consisted of a 

predominance of nearshore crabs and mollusks, as well as fish, shrimp, and other foods considered 

to be shrimp fishery discards (Shaver, 1991). Pelagic stage, neonatal Kemp’s ridleys presumably 

feed on the available Sargassum and associated infauna or other epipelagic species found in the 

GOM (USDOI, FWS, 2015a). Shaver et al. (2013) described Kemp’s ridley nearshore foraging 

habitat “hotspots” in the northern GOM and, in another study, rehabilitated juveniles that were 

released showed similar foraging areas in coastal areas of Louisiana and Florida (Lyn et al., 2012).

Of the five species in the GOM, the Kemp’s ridley has suffered the greatest population 

decline, and historically, that decline was caused by commercial and local exploitation. Many natural 

and anthropogenic threats to the future of the species remain, including interactions with fishery gear

(and managing agencies’ continued concern for the adequacy of existing regulatory mechanisms), 

dredging, marine pollution, foraging habitat destruction, entrainment in power plant cooling system 

intake structures, potential for illegal poaching of nests, cold stunning (turtles are lethargic and 

stressed from cold temperatures, which could lead to disorientation and mortality), and the potential 

threats to nesting beaches from such sources as global climate change and development (USDOC, 

NMFS and USDOI, FWS 2015). 
Description of the Affected Environment and Impact Analysis 4-271

Green Sea Turtle

Federal listing of the green sea turtle occurred on July 28, 1978 (Federal Register, 1978). All 

green sea turtle populations are listed as threatened except for the breeding populations of Florida 

and the Pacific Coast of Mexico, which are endangered. The NMFS and FWS have proposed a rule 

(Federal Register, 2015g) to remove the current range-wide listing for green sea turtles, to replace it 

with eight DPSs as threatened and three as endangered, and to include application of existing 

protective regulations to the DPSs. Green sea turtles found in the GOM are proposed to be part of 

the threatened North Atlantic DPS (Federal Register, 2015g).

Green sea turtle mating occurs in the waters off the nesting beaches. Each female deposits 

1-7 clutches (usually 2-3) during the breeding season at 12- to 14-day intervals. Mean clutch size is 

highly variable among populations but averages about 110 eggs. Females usually have 2-4 years 

between breeding seasons, while males may mate every year (Balazs, 1983). The complete nesting 

range of the green sea turtle includes sandy beaches of mainland shores, barrier islands, coral 

islands, and volcanic islands between Texas and North Carolina and at the U.S. Virgin Islands and 

Puerto Rico (USDOC, NMFS and USDOI, FWS, 1991). Principal U.S. nesting areas for green sea 

turtles are in eastern Florida (Ehrhart and Witherington, 1992), but the most important nesting 

concentration in the western Atlantic is in Costa Rica because it has increased markedly since the 

1970s (USDOI, NMFS and USDOI, FWS, 2007c).

After hatching, green sea turtles go through a post-hatchling pelagic stage where they move 

offshore and are associated with drift lines of algae, Sargassum, and other debris. The posthatchlings are believed to live within these drift lines for several years, feeding close to the surface 

on a variety of pelagic plants and animals. The post-hatchling, pelagic-stage individuals are 

assumed to be omnivorous, but little data are available. Once the juveniles reach a certain age/size 

range, they leave the pelagic habitat and travel to nearshore foraging grounds. Once they move to 

these nearshore benthic habitats, adult green turtles are almost exclusively herbivores, feeding on 

seagrasses and algae. Age at sexual maturity is estimated to be between 20 and 40 years 

(USDOC, NMFS and USDOI, FWS, 2007c). Adult females migrate from foraging areas to mainland 

or island nesting beaches and may travel hundreds or thousands of kilometers each way (USDOC, 

NMFS and USDOI, FWS, 2007c).

Green sea turtles depend on shallow foraging grounds with sufficient benthic vegetation. 

Direct destruction of foraging areas from dredging, boat anchorage, deposition of spoil, and siltation 

(Coston-Clements and Hoss, 1983; Williams, 1988) may have considerable impacts on the 

distribution of foraging green turtles. Eutrophication, heavy metals, radioactive elements, and 

hydrocarbons all may reduce the extent, quality, and productivity of foraging grounds (Frazier, 1980; 

USDOC, NMFS and USDOI, FWS, 2007c).

The principal cause of past declines and extirpations of green sea turtle assemblages has 

been the over exploitation for eggs and meat. Significant threats on green turtle nesting in the 

region include beach armoring and erosion control, artificial lighting, and general disturbance from 
4-272 Gulf of Mexico Multisale EIS

human activity, such as trampling. Armoring of beaches (e.g., seawalls, revetments, rip-rap, 

sandbags, and sand fences) in Florida, which is meant to protect developed property, is increasing 

and has been shown to discourage nesting, even when armoring structures do not completely block 

access to nesting habitat (Mosier, 1998). Marine debris is a threat to the pelagic habitat of juvenile 

green turtles. Older juvenile green turtles have also been found dead after ingesting seaborne 

plastics (Balazs, 1985). A major threat from manmade debris is the entanglement of turtles in 

discarded monofilament fishing line and abandoned netting (Balazs, 1985). This can have physical 

impacts in addition to more susceptibility to disease.

Ongoing threats to green sea turtles include the occurrence of green turtle 

fibropapillomatosis disease, which was originally reported in the 1930’s (Smith and Coates, 1938). 

This disease is globally widespread and has been found to affect large numbers of animals in some 

areas, including Hawaii and Florida (Herbst, 1994; Jacobson, 1990; Jacobson et al., 1991). The 

tumors related to this disease are commonly found in the eyes, occluding sight. It was thought for 

many years that the cause of this disease was contributed by environmental pollutants; however, 

Keller et al. (2014) found the causing factor of fibropapillomatosis is not only related to 

environmental pollutants. Gillnets, trawl nets, pound nets (Crouse, 1982; Hillestad et al., 1982; 

NRC, 1990), and abandoned nets of many types (Balazs, 1985; Ehrhart et al., 1990) are known to 

kill sea turtles as bycatch. To address interactions between marine turtles and trawl fishing gear, the 

NOAA worked cooperatively with the commercial shrimp trawl industry to develop sea turtle excluder 

devices (Federal Register, 2015g). Green sea turtles are also threatened and taken by hook-andline fishing. Collisions with power boats and encounters with suction dredges have killed green sea 

turtles along the U.S. coast and may be common elsewhere where boating and dredging activities 

are frequent.

Leatherback Sea Turtle

The leatherback sea turtle was listed as endangered on December 2, 1970 (Federal 

Register, 1970b). Leatherback distribution and nesting grounds are found around the world in 

waters of the Atlantic, Pacific, and Indian Oceans; the Caribbean Sea; and the Gulf of Mexico (Ernst 

et al., 1994; USDOC, NMFS and USDOI, FWS 2013a). Adult leatherbacks forage in temperate and 

subpolar regions from 71°N. to 47°S. latitude in all oceans and undergo extensive migrations 

between 90°N. and 20°S. latitude to and from the tropical nesting beaches (USDOC, NMFS and 

USDOI, FWS 2013a). Female leatherbacks nest from the southeastern U.S. (east coast of Florida) 

to southern Brazil in the western Atlantic Ocean and from Mauritania to Angola in the eastern 

Atlantic Ocean (USDOC, NMFS and USDOI, FWS, 2013a; USDOI, FWS, 2015b).

The leatherback is the most abundant sea turtle in waters over the northern GOM continental 

slope (Mullin and Hoggard, 2000). Leatherbacks appear to spatially use continental shelf and slope 

habitats in the GOM (Collard and Ogren, 1990; Davis and Fargion, 1996). Surveys indicate the 

region from Mississippi Canyon to De Soto Canyon, especially near the shelf edge, appears to be an 

important habitat for leatherbacks (Mullin and Hoggard, 2000). Leatherbacks have been frequently 

sighted in the GOM during summer and winter (Mullin and Hoggard, 2000). They nest frequently (up 
Description of the Affected Environment and Impact Analysis 4-273

to 7 nests per year) during a nesting season and nest about every 2-3 years, although nesting is rare 

on GOM beaches (State of Florida, Fish and Wildlife Conservation Commission, 2015). There was a 

recorded nest site in Texas during the 2008 season (USDOI, NPS, 2008). Most nesting occurs 

outside the GOM.

The leatherback is the largest and most pelagic of sea turtles. The average curved carapace 

length for adults is 61 in (155 cm) and weights from worldwide populations range from 441 to 

1,543 lb (200 to 700 kg). The leatherback forages widely throughout the water column from the 

surface to great depths throughout tropical and temperate oceans of the world. The distribution of 

leatherbacks appears to be dependent upon the distribution of their prey (Leary, 1957), consisting 

mostly of jellyfish and other pelagic gelatinous organisms, such as tunicates. Adults have been 

tracked foraging in the GOM (Evans, 2006). Adult leatherbacks are deep divers, with estimated 

dives to depths in excess of 3,281 ft (1,000 m) (Eckert et al., 1989), but they may come into shallow 

waters if there is an abundance of jellyfish nearshore. Little is known about the pelagic habits of the 

hatchlings and juveniles, and they have not been documented to be associated with the Sargassum 

areas as are the other four species. Details about Sargassum can be found in Chapter 4.5

(Sargassum and Associated Communities).

The current estimate of the northern Atlantic population, which includes the GOM, is 

34,000-94,000 adults (USDOC, NMFS and USDOI, FWS, 2013a). Leatherbacks are a long-lived 

species (>30 years), with an estimated age at sexual maturity reported at about 3-19 years (Zug and 

Parham, 1996). During each nesting, females may produce 100 eggs or more in each clutch 

(Schultz, 1975), although the leatherback clutches recorded at Buck Island in 2014 ranged from 

48 to 72 (Pollock et al., 2015). The eggs require approximately 60 days of incubation until the turtle 

breaks through the shell. 

Ongoing threats to leatherbacks include ingestion of marine debris (Shoop and Kenney, 

1992; Bugoni et al., 2001; Mrosovsky et al., 2009), poaching of eggs and animals (Boulon, 2000), 

entanglement in longline fishing gear (USDOC, NMFS, 2001), coastal trawl, and net and longline 

fisheries (Marcano and Alio-M, 2000; USDOC, NMFS, 2007b). Leatherback sea turtles seem to be 

the most susceptible to entanglement. This susceptibility may be the result of attraction to 

gelatinous organisms and algae that collect on buoys and buoy lines at or near the surface, and 

perhaps to the lightsticks used to attract target species in the longline fishery. According to observer 

records, an estimated 6,363 leatherback sea turtles were caught by the U.S. Atlantic tuna and 

swordfish longline fisheries between 1992 and 1999, of which 88 were discarded dead (USDOC, 

NMFS, 2001). Since then, U.S. pelagic longline fisheries in the Atlantic have incorporated 

mandatory bycatch reduction measures (USDOC, NMFS and USDOI, FWS, 2013a). However, 

Atlantic (including the Mediterranean, which has much higher fishing effort) longline sea turtle 

bycatch rates are higher than Pacific bycatch (Lewison et al., 2004). Reports of incidental takes of 

leatherback turtles are incomplete for many nations, including and in particular the GOM (USDOC, 

NMFS, 2001).
4-274 Gulf of Mexico Multisale EIS

Hawksbill Sea Turtle

The hawksbill turtle was listed as endangered on December 2, 1970 (Federal Register, 

1970b). Hawksbill sea turtles were once abundant in tropical and subtropical regions. Hawksbill sea 

turtles are highly migratory and use a wide range of habitats during their lifetime. In the continental 

U.S., hawksbills are found primarily in Florida and Texas, although they have been recorded in all 

the Gulf Coast States and along the east coast as far north as Massachusetts.

While most nesting occurs throughout the world’s oceans with the most nests found in 

beaches of the Caribbean Sea, hawksbill nesting on northern GOM beaches, including Florida, is 

rare (Mays and Shaver, 1998; USDOI, FWS, 2015c). The Atlantic Coast of Florida is the only area 

in the U.S. where hawksbills nest on a regular basis, but the maximum number of nests documented 

in any year during 1979-2000 was only four.

The life history of hawksbills consists of a pelagic stage that lasts from the time they leave 

the nesting beach as hatchlings until they are approximately 7-12 in (20-30 cm) in straight carapace 

length (Meylan, 1988; Bell and Pike, 2012), followed by residency in developmental habitats 

(foraging areas where immature individuals reside and grow) in coastal waters. As with most sea 

turtle species, hatchlings and early juveniles are often found in association with oceanic Sargassum 

floats. As later juveniles, they move nearshore for feeding habitat and may associate with the same 

feeding locality for more than a decade (Musick and Limpus, 1997). Adult foraging habitat, which 

may or may not overlap with developmental habitat, is typically coral reefs, although other hard 

bottom communities and occasionally mangrove-fringed bays may be occupied. Hawksbills show 

fidelity to their foraging areas over periods of time as great as several years (van Dam and Diez, 

1998). The diet is highly specialized and consists primarily of sponges and macroalgae, although 

other food items have been documented to be important in some areas of the Caribbean (USDOC, 

NMFS and USDOI, FWS, 2013b). The lack of sponge-covered reefs and the cold winters in the 

northern GOM may prevent hawksbills from establishing a strong population in this area.

The majority of hawksbill sightings are reported from the sea turtle stranding network. 

Hawksbills may undertake developmental migrations (movements as immature turtles) and 

reproductive migrations that involve travel over hundreds or thousands of kilometers (Meylan, 1999). 

Reproductive females undertake periodic (usually non-annual) migrations to their natal beach to 

nest. Movements of reproductive males are less well known, but they are presumed to involve 

migrations to the nesting beach or to courtship stations along the migratory corridor. Females nest 

an average of 3-5 times per season, and the mean clutch size is 130 eggs (USDOC, NMFS and 

USDOI, FWS, 2013b). Immature hawksbills tagged at St. Thomas during long-term, in-water studies 

appeared to be resident for extended periods (Boulon, 1994). Tag returns were recorded from St. 

Lucia, the British Virgin Islands, Puerto Rico, U.S. Virgin Islands, and the Dominican Republic 

(Boulon, 1989; Meylan, 1999; USDOC, NFMS and USDOI, FWS, 2013b).

In addition to the factors threatening all marine turtles (described in the sea turtle introduction 

above), hybridization with other species has also been identified as a problem for hawksbills 
Description of the Affected Environment and Impact Analysis 4-275

(USDOC, NMFS and USDOI, FWS, 2013b). The primary cause of hawksbill decline has been 

attributed to centuries of exploitation for tortoiseshell, the beautifully patterned scales that cover the 

turtle’s shell (Parsons, 1972; Mortimer and Donnelly, 2008). International trade in tortoiseshell is 

now prohibited among all signatories of the Convention on International Trade in Endangered 

Species; however, some illegal trade continues, as does trade between nonsignatories. Globally, 

hawksbills are affected in foraging areas and on nesting beaches by climate change and fisheries 

bycatch (USDOC, NMFS and USDOI, FWS, 2013b).

Critical Habitat

Of all five GOM sea turtles species, the loggerhead is the only sea turtle that has critical 

habitat established in the GOM (Figure 4-23). As described above, the NMFS and FWS are jointly 

responsible for managing sea turtles. The NMFS designated marine critical habitats in its Final Rule 

in July 2014, and the FWS designated terrestrial critical habitat in its Final Rule in August 2014 

(Federal Register, 2014a and 2014c). The offshore marine critical habitat is Sargassum and the 

terrestrial critical habitat is beaches (Figure 4-23).

Four of the five species of sea turtles found in the GOM are associated with floating 

Sargassum (Carr, 1987b; Coston-Clements et al., 1991; Schwartz, 1988; Witherington et al., 2012). 

The hatchlings of loggerhead, Kemp’s ridley, green, and hawksbill sea turtles are thought to find the 

Sargassum rafts when actively seeking frontal zones and then utilizing the habitat as foraging 

grounds and protection during their pelagic “lost years” (juvenile years in which turtle sightings are 

scarce) (Carr, 1987b; Coston-Clements et al., 1991). Schwartz (1988) reported numerous 

loggerhead hatchlings during commercial trawling for Sargassum in the Atlantic. This provided the 

largest count of hatchlings on record to date. Witherington et al. (2012) conducted a study on 

juvenile turtle use of Sargassum habitats and further supported that these drifting communities are 

important areas for young sea turtles (84% of 1,884 turtles were observed within 1 m [3 ft] of floating 

Sargassum). Sea turtle digestive system samples contained mainly marine animals and plants, 

plastics, wood, and flying insects. Tarballs, oiled plastics, and liquid oil were observed in Sargassum

drift lines during the surveys (Witherington et al., 2012). Putman and Mansfield (2015) reported that 

passive-drifting sea turtle juveniles (Sargassum-associated stage) were actually active swimmers. 

Their research used synchronized surface drifter and tagged turtle releases to support that sea 

turtles in the GOM are able to move independently from and not dispersed solely by currents 

(Putnam and Mansfield, 2015). Details about Sargassum can be found in Chapter 4.5 (Sargassum 

and Associated Communities).

4.9.2.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from activities described in Chapter 3

and their potential impacts on sea turtles that would potentially result from a single lease sale or the 

alternatives. This analysis applies to all considered alternatives. While the WPA is a smaller area 

with less projected activity than is proposed for the CPA/EPA (refer to Chapter 3), sea turtles are 

distributed throughout the planning areas. As such, activities isolated to specific planning areas 
4-276 Gulf of Mexico Multisale EIS

pose similar potential impacts to populations as do activities occurring in all planning areas. 

Therefore, because of the free swimming ability and wide distribution of species across the Area of 

Interest, the level of impacts would be the same for Alternatives A, B, C, and D. However, 

Alternative E, No Action, would avoid impacts from a proposed lease sale and the related postlease 

activities as the lease sale would not be held; only impacts from past lease sales and associated 

postlease activities or other G&G permits would continue. Following this environmental 

consequences chapter, there will be a summary of the potential impacts as they relate to the other 

action alternatives.

Routine Activities

Routine activities (described in Chapter 3.1) resulting from a proposed action have the 

potential to harm sea turtles, although this potential is unlikely to rise to a level of significance to the 

population due to the activity already present in the GOM and mitigations that have been historically 

applied and discussed below. The routine activities that could have impact-producing factors 

associated with a proposed action that may affect GOM sea turtles include geological and 

geophysical activities (Chapter 3.1.2.1), transportation (Chapter 3.1.4), discharges and wastes 

(Chapter 3.1.5), marine debris (Chapter 3.1.5.3.4) decommissioning (Chapter 3.1.6), and noise 

(Chapter 3.1.9). Scenario numbers presented in this chapter are for Alternative A, which represents 

a regionwide lease sale with expected lease stipulations for this and other alternative scenario 

numbers (refer to Table 3-2).

Geological and Geophysical Activities

Seismic operations have the potential to harm sea turtles in close proximity to firing airgun 

arrays. The Protected Species Stipulation and NTL 2012-JOINT-G02, “Implementation of Seismic 

Survey Mitigation Measures and Protected Species Observer Program,” minimize the potential of 

harm from seismic operations to sea turtles that could be within the exclusion zone. These 

mitigations include, but are not limited to, onboard observers, ramp-up procedures, and the use of a 

minimum sound source. Noise impacts on turtles from seismic surveys are described in the “Noise”

section below.

Further detailed information on seismic surveys and other G&G survey types may be found 

in Chapter 3.1.2.1. More information on sea turtle hearing and sensitivity to acoustic impacts can be 

found in Appendix I of BOEM’s Atlantic OCS Proposed Geological and Geophysical Activities: MidAtlantic and South Atlantic Planning Areas, Final Programmatic Environmental Impact Statement, 

(USDOI, BOEM, 2014a) and Appendix H of the Geological and Geophysical Exploration for Mineral 

Resources on the Gulf of Mexico Outer Continental Shelf: Final Programmatic Environmental 

Assessment, (USDOI, MMS, 2004b). Noise associated with G&G activities may cause behavioral 

effects (changes in direction or swimming speed) or auditory masking in sea turtles. Based on 

current information on sea turtle hearing capabilities, it is not clear whether or not sea turtles rely on 

sound or would be affected by auditory masking (Popper et al., 2014). For more on noise impacts, 

refer to the “Noise” section below. In addition, the NMFS, BOEM, and BSEE collaborated to publish 

National Standards for a Protected Species Observer Program to reduce impacts to protected 
Description of the Affected Environment and Impact Analysis 4-277

species from G&G activities by standardizing the variation in and improving the management of the 

program (Baker et al., 2013).

The only other impact-producing factor to sea turtles that is associated with G&G activities is 

the potential for gear interaction. Sea turtles can become entangled in some types of lines 

associated with G&G activities. Entanglement could cause stress, injury, and mortality of sea turtles. 

The G&G permit applications set conditions of approval with each activity that would minimize 

specific impacts caused by gear interactions. Sea turtle gear interaction impacts associated with 

G&G activities are expected to be rare. With the implementation of mitigations, impacts from G&G 

activities would be expected to be negligible to moderate. 

Transportation

An estimated 29,000-270,000 (highest range under Alternative A) service-vessel roundtrips 

are expected to occur annually as a result of a proposed action. Transportation corridors would be 

through areas where sea turtles have been sighted. Helicopter operation round trips are expected to 

be 87,000-1,928,000 as a result of a proposed action. Noise from service-vessel traffic and 

helicopter overflights may elicit a startle reaction from sea turtles, and there is the possibility of shortterm disruption of activity patterns. For noise impacts related to OCS vessel and air traffic activities, 

refer to the “Noise” section below. Other impacts related to transportation are described in this 

section. 

Vessel strikes are impact-producing factors associated with transportation associated with a 

proposed action that could affect sea turtles. Sea turtles spend at least 3-6 percent of their time at 

the surface for respiration and perhaps as much as 26 percent of their time at the surface for 

basking, feeding, orientation, and mating (Lutcavage et al., 1997). Data show that collisions with all 

types of commercial and recreational vessels are a cause of sea turtle mortality in the GOM 

(Lutcavage et al., 1997). Stranding data for the U.S. Gulf and Atlantic Coasts, Puerto Rico, and the 

U.S. Virgin Islands show that, between 1986 and 1993, about 9 percent of living and dead stranded 

sea turtles had boat strike injuries (Lutcavage et al., 1997).

Sea turtles located in shallower waters have shorter surface intervals, whereas turtles 

occurring in deeper waters have longer surface intervals. It is not known whether turtles exposed to 

recurring vessel disturbance would be stressed or otherwise affected in a negative but 

inconspicuous way. Increased vessel traffic would increase the probability of collisions between 

vessels and turtles, potentially resulting in injury or death to some animals.

There have been no documented sea turtle strikes with drilling and service vessels in the 

GOM; however, collisions with small or submerged sea turtles may go undetected. Based on sea 

turtle density estimates in the GOM, the encounter rates between sea turtles and vessels would be 

expected to be greater in water depths <200 m (656 ft) (USDOC, NMFS, 2007b). To further 

minimize the potential for vessel strikes, NTL 2012-JOINT-G01 was issued; this NTL provides the 

NMFS guidelines for monitoring procedures related to vessel strike avoidance measures for sea 
4-278 Gulf of Mexico Multisale EIS

turtles and other protected species. BOEM uses the Protected Species Stipulation, for which 

guidelines are mandated, in the lease after a proposed lease sale. With the implementation of these 

measures and the avoidance of potential strikes from OCS vessels, the risk of collisions between oiland gas-related vessels (including those for G&G, drilling, production, decommissioning, and 

transport) and sea turtles is appreciably reduced, but strikes may still occur. BOEM and BSEE 

monitor for any takes that have occurred as a result of vessel strikes and require that any operator 

immediately report the striking of any animal (NTL 2012-JOINT-G01). Given the scope, timing, and 

transitory nature of a proposed action and with this established mitigation, the impacts to sea turtles 

from vessel collisions are expected to be negligible; however, if collisions occur, impacts could be 

moderate. 

Discharges and Wastes

Contaminants in waste discharges and drilling muds might indirectly affect sea turtles 

through food-chain biomagnification, but there is uncertainty concerning the possible impacts. Most 

operational discharges are diluted and dispersed when released in offshore areas and are 

considered to have sublethal effects (Kennicutt, 1995; Kennicutt et al., 1996). Any potential impacts 

from drilling fluids would be indirect as a result of ingestion via the food chain (Neff et al., 1989). 

Impacts from water degradation are expected to be negligible due to rapid dilution of the 

discharges, which are also regulated by NPDES permits, and due to the wide-ranging movements of 

sea turtle species in the GOM. Refer to Chapter 3.1.5 for more information on operational wastes 

and discharges generated by OCS oil- and gas-related facilities.

Marine Trash and Debris

A wide variety of trash and debris is commonly observed in the GOM. Marine debris remains 

a continuous threat to sea turtles (Schuyler et al, 2014). Marine trash and debris comes from a 

variety of land-based and ocean sources (Cottingham, 1988). Some material is accidentally lost 

during drilling and production operations. Turtles may become entangled in drifting debris and 

ingest fragments of synthetic materials (Carr, 1987b; USDOC, NOAA, 1988; Mrosovsky et al., 2009; 

Santos et al., 2015). Once entangled, turtles may drown, incur impairment to forage or avoid 

predators, sustain wounds and infections from the abrasive or cutting action of attached debris, or 

exhibit altered behavior that threaten their survival (Laist, 1997). Both entanglement and ingestion 

have caused the death or serious injury of individual sea turtles (Balazs, 1985). Balazs (1985) 

compiled dozens of records of sea turtle entanglement, ingestion, and impaction of the alimentary 

canal by ingested plastics.

The marked tendency of leatherbacks to ingest plastic has been attributed to the 

misidentification of the translucent films as jellyfish. Lutz (1990) concluded that turtles would actively 

seek out and consume plastic sheeting. Ingested debris may block the digestive tract or remain in 

the stomach for extended periods, thereby lessening the feeding drive, causing ulcerations and 

injury to the stomach lining, or perhaps even providing a source of toxic chemicals (Laist, 1997). 

Microplastics are becoming an increasing concern for ingestion by sea turtles and can also decrease 

maximum temperatures in beach sediments, which can create sexual bias in sea turtles (Bergmann 
Description of the Affected Environment and Impact Analysis 4-279

et al., 2015). Weakened animals are then more susceptible to predators and disease; they are also 

less fit to swim, breed, or nest successfully.

Witherington (1994) studied post-hatchling loggerheads in drift lines 8-35 nmi (9-15 mi; 

15-24 km) east of Cape Canaveral and Sebastian Inlet, Florida. Out of 103 turtles captured, 

17 percent of the animals contained plastic or other synthetic fibers in their stomachs or mouths. 

Without mitigation, marine debris impacts would be negligible to moderate. Operators must comply 

with the guidelines provided in NTL 2015-BSEE-G03, “Marine Trash and Debris Awareness and 

Elimination.” Following a lease sale, the NTLs would become mandatory under the Protected 

Species Stipulation. The BSEE prohibits the disposal of equipment, containers, and other materials 

into offshore waters by lessees (30 CFR § 250.300). In addition, MARPOL, Annex V, Public Law 

100-220 (101 Statute 1458) prohibits the disposal of any plastics at sea or in coastal waters. 

Therefore, expected marine debris impacts to sea turtles from a proposed action should be 

negligible. 

Decommissioning

Offshore structures serve as artificial reefs and are sometimes used by sea turtles for 

foraging and resting (Gitschlag and Herczeg, 1994). Explosive severance of these structures can 

affect turtles located in the vicinity of the structure during the severance activity. The estimated 

number of platforms to be decommissioned as a result of a selected alternative is reported in 

Chapter 3.1.6. With the highest range under Alternative A, an estimated 9-193 projects of explosive 

severance of structure removals are projected to occur (Table 3-2). 

Decommissioning activities, which are approved by BSEE, are described in detail in 

Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf: Programmatic 

Environmental Assessment (USDOI, MMS, 2005), and they are described in Chapter 3. The 

previously issued NTL, “Decommissioning Guidance for Wells and Platforms” (NTL 2010-G05) 

provides guidelines for offshore operators that specify and reference NMFS’s biological opinion 

mitigation requirements currently in place for protected species, including sea turtles. In addition, 

terms and conditions, and reasonable and prudent measures identified during consultation for 

decommissioning would be required conditions of approval in any decommissioning authorizations. 

The regulations outline the environmental, monitoring, and mitigation information that operators must 

submit with plans for exploration, development, and production. This regulation requires OCS 

energy-related activities to be conducted in a manner that is consistent with the provisions of the 

ESA. Additionally, the NMFS has implemented a protected species observer program for structure 

decommissioning. Actual sea turtle impacts from explosive removals in recent years have been 

small. Though mitigations that are in place would minimize the risk of impacts to sea turtles, there is 

a possibility of sea turtles going undetected within the zone of explosive impacts. The updated preand post-detonation mitigations should ensure that injuries remain extremely rare. Explosive 

severance could moderately impact sea turtles; however, with implementation of specified 

decommissioning mitigations, impacts to sea turtles from explosive severance are expected to be 

negligible. 
4-280 Gulf of Mexico Multisale EIS

Noise

Noise-induced stress has not been well-studied in sea turtles. Captive loggerhead and 

Kemp’s ridley turtles exposed to brief audio-frequency vibrations initially showed startle responses of 

slight head retraction and limb extension (Lenhardt et al., 1983). Sound-induced swimming 

response has been observed for captive loggerhead and green sea turtles (O’Hara and Wilcox, 

1990; Moein et al., 1993; Lenhardt, 1994). Loggerhead hearing frequency range is between 50 and 

1100 Hz, depending on the size of the turtle (Lavender et al., 2014). Some loggerheads exposed to 

low-frequency sound responded by swimming towards the surface at the onset of the sound, 

presumably to lessen the effects of the transmissions (Lenhardt, 1994). The potential direct and 

indirect impacts of sound on sea turtles include physical auditory impacts (temporary threshold shift), 

behavioral disruption, long-term impacts, masking, and adverse impacts on the food chain. Lowfrequency sound transmissions could potentially cause increased surfacing and avoidance from the 

area near the sound source (Lenhardt et al., 1983; O’Hara and Wilcox, 1990; McCauley et al., 2000). 

Leatherback hatchlings were shown to detect sounds between 50 and 1,200 Hz underwater and 

50 and 1,600 Hz in air with maximum sensitivity between 100 and 400 Hz in water and 50 and 400 in 

air (Dow Piniak et al., 2012).

For seismic sources, sea turtles have the potential for mortality or injury at or above 210 dB 

cumulative sound exposure level and above 207 dB peak pressure level (Popper et al., 2014). Sea 

turtles have been observed noticeably increasing their swimming in response to an operating 

seismic source at 166 dB in water (McCauley et al., 2000). There is a high potential for recoverable 

injury, temporary threshold shift (recoverable hearing loss), and behavioral modifications only when 

the turtle is in close proximity to the source. Mortality and injury caused by shipping and continuous 

noise are expected to have low levels of relative risk even if a sea turtle is near the source. The risk 

for temporary threshold shift near the source is moderate, while the risk for masking may be high 

both at near and intermediate distances from the source, and the risk for behavioral modifications 

near the source are high and moderate at intermediate distances from the source (Popper et al.,

2014). Impacts from any sound source are relative to the source type, distance to the source, 

frequency, intensity and duration of the source, and distance to the animal. Refer to Chapter 3.1.2.1

for more information on noise related to G&G activities.

Reactions to aircraft or vessel noise, such as avoidance behavior, may disrupt normal 

activities, including feeding. Important habitat areas (e.g., feeding, mating, and nesting) may be 

avoided because of noise generated in the vicinity. There is no information regarding the 

consequences that these disturbances may have on sea turtles in the long term. There are no 

systematic studies published of the reactions of sea turtles to aircraft overflights; however, anecdotal 

reports indicate that sea turtles often react to the sound and/or the shadow of an aircraft by diving. It 

is projected that 70,000-3,750,000 OCS oil- and gas-related helicopter operations (take-offs and 

landings) would occur annually in the support of OCS oil- and gas-related activities (Table 3-2). The 

Federal Aviation Administration’s Advisory Circular 91-36D (September 17, 2004) encourages pilots 

to maintain higher than minimum altitudes over noise-sensitive areas. Vessel noise is an impactproducing factor associated with a proposed action that could affect sea turtles. The dominant 
Description of the Affected Environment and Impact Analysis 4-281

source of noise from vessels is propeller operation (i.e., cavitation), and the intensity of this noise is 

largely related to ship size and speed. Noise from service-vessel traffic may elicit a startle reaction 

from sea turtles and produce a temporary sublethal stress (NRC, 1990). Startle reactions may result 

in increased surfacings, possibly causing an increase in risk of vessel collision. Vessel noise from 

activities resulting from a proposed action would produce low levels of noise, generally in the 150- to 

170-dB re 1 μPa-m and at frequencies below 1,000 Hz. Vessel noise is transitory and generally 

does not propagate at great distances from the vessel. If sound affects any prey species, impacts to 

sea turtles would depend on the extent that prey availability might be altered.

Drilling and production facilities produce an acoustically wide range of sounds at frequencies 

and intensities that could possibly be detected by turtles. Drilling noise from conventional metallegged structures and semisubmersibles is not particularly intense and is strongest at low 

frequencies (Richardson et al., 1995). A few preliminary investigations using adult green, 

loggerhead, and Kemp’s ridley turtles suggest that they are most sensitive to low-frequency sounds 

(Ridgway et al., 1969; Lenhardt et al., 1983; Moein et al., 1999). It has been suggested that sea 

turtles use acoustic signals from their environment as guideposts during migration and as a cue to 

identify their natal beaches (Lenhardt et al., 1983). Bone-conducted hearing appears to be a 

reception mechanism for at least some of the sea turtle species, with the skull and shell acting as 

receiving structures (Lenhardt et al., 1983). Oil and gas exploration and extraction occur in sea 

turtle foraging habitats and generates high-intensity, low-frequency, impulsive sounds within the 

leatherback hearing range (Dow Piniak et al., 2012).

Chronic sublethal effects (e.g., stress), resulting in persistent physiological or behavioral 

changes and/or avoidance of impacted areas from noise disturbance such as seismic activities, 

could cause declines in survival or fecundity and could result in population declines; however, such 

declines are not expected because of implementation of the Protected Species Stipulation and NTL 

2012-JOINT-G02 minimizing potential harm. Overall noise impacts on sea turtles from a proposed 

action are expected to be negligible to minor depending on the location of the animal(s) relative to 

the sound source and the frequency, intensity, and duration of the source. A minor impact would be 

a behavioral change in response to noise. Refer to Chapter 3.1.9 for more information on potential 

noise impact-producing factors associated with a proposed action.

Accidental Events

Reasonably foreseeable accidental events as a result of a proposed action have the 

potential to harm sea turtles. The major impact-producing factors resulting from the accidental 

events associated with a proposed action that may affect sea turtles include oil spills and spillresponse activities. These have the potential to impact small to large numbers of sea turtles in the 

GOM, depending on the magnitude and frequency of low-probability accidents, the ability to respond 

to accidents, the location and date of accidents, various meteorological and hydrological factors, and 

life history stages of animals exposed to the hydrocarbons (NRC, 2003; USDOC, NMFS, 2015h).
4-282 Gulf of Mexico Multisale EIS

Oil Spills

Improperly balanced well pressures that result in sudden, uncontrolled releases of fluids from 

a wellhead or wellbore can occur during any phase of development (i.e., exploratory drilling, 

development drilling, production, completion, or workover operations [refer to Chapter 3.2.1 for 

description of development activities]). Though oil and gas exploration overlaps sea turtles habitats, 

it is the particular biology and behavior of sea turtles that place them at risk, including a lack of 

avoidance behavior, indiscriminate feeding in convergence zones, and large pre-dive inhalations 

(Shigenaka et al., 2010). Oil spills, however, are not the foremost danger to sea turtles, as 

described above. Impacts would occur as a result of actual contact with the spilled oil, regardless of 

the source.

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. Sea turtles accidentally exposed to oil or tarballs 

may suffer inflammatory dermatitis, ventilatory disturbance, salt gland dysfunction or failure, red 

blood cell disturbances, immune responses, and digestive disorders or blockages (Vargo et al., 

1986; Lutz and Lutcavage, 1989; Lutcavage et al., 1995). Significant changes in blood chemistry 

following contact with hydrocarbons have been reported ranging from changes to blood’s oxygen 

transport system to elevation in white blood cells, indicating stress (Lutcavage et al., 1995). 

Although disturbances may be temporary, long-term impacts remain unknown, and chronically 

ingested oil may accumulate in organs. Oil can adhere to the body surface of marine turtles. Oil has 

been observed to cling to the nares, eyes, and upper esophagus (Overton et al., 1983; Van Vleet 

and Pauly, 1987; Gramentz, 1988; Lutcavage et al., 1995). Witham (1983) found tar sealed the 

mouth and nostrils of small turtles. Periocular tissues and other mucous membranes would 

presumably be most sensitive to contact with hydrocarbons. Turtles may become entrapped by tar 

and oil slicks and rendered immobile (Witham, 1978; Plotkin and Amos, 1988; Gramentz, 1988). All 

structural and biochemical changes in the epidermis of sea turtles have been shown to be minor and 

reversible. A break in the skin barrier could act as a portal of entry for pathogenic organisms, 

leading to infection, neoplastic conditions, and debilitation (Vargo et al., 1986).

Contact with hydrocarbons may not cause direct or immediate death but cumulative 

sublethal impacts, such as salt gland disruption or liver impairment, could impair a sea turtle’s ability 

to function effectively in the marine environment (Vargo et al., 1986; Lutz and Lutcavage, 1989; 

Camacho et al., 2012). Although many observed physiological insults are resolved in a 21-day 

recovery period, the impact of tissue oil intake on the long-term health and survival of sea turtles 

remains unknown (Lutcavage et al., 1995). Camacho et al. (2013) conducted blood plasma testing 

on stranded sea turtles to determine PAH concentrations. Burning fossil fuels and urban runoff, as 

well as oil spills, were considered as being potential environmental sources of PAHs detected in 

turtle blood plasma (Camacho et al., 2013). A similar study was conducted by Camacho et al. 

(2014) on live juvenile turtles and it was determined that the turtles had 34 of 52 organic 

contaminants. Contrary to previous data (Geraci and St. Aubin, 1983), PAH biomagnification does 

not occur in sea turtles, suggesting that sea turtles may be able to efficiently metabolize PAHs 

(Camacho et al., 2014).
Description of the Affected Environment and Impact Analysis 4-283

Eggs, hatchlings, and small juveniles are particularly vulnerable if contacted (Fritts and 

McGehee, 1982; Lutz and Lutcavage, 1989; Bjorndal et al., 1994). Sea turtle hatchling exposure to, 

fouling by, or consumption of tarballs would likely be fatal. Sea turtle eggs are likely to be lethally 

impacted by contact with spilled oil (USDOI, NPS, 2011a). During nesting, a female turtle might 

crawl through tar prior to laying her eggs or might push oil mixed with sand into the nest and 

contaminate the eggs (Chan and Liew, 1988). Assuming a sea turtle’s sense of smell is critical, oil 

fouling of a nesting area might disturb imprinting of hatchling turtles or confuse the turtles on their 

return migration (Geraci and St. Aubin, 1985; Chan and Liew, 1988). Potential toxic impacts to 

embryos would depend on the type of oil and degree of weathering, type of beach substrate, and 

especially upon the developmental stage of the embryo. Embryonic development in an egg may be 

altered or arrested by contact with oil (Fritts and McGehee, 1982). Fresh oil was found to be highly 

toxic, especially during the last quarter of the incubation period, whereas aged oil produced no 

detectable impacts. Fritts and McGehee (1982) concluded that oil contamination of nesting beaches 

would have its greatest impact on nests that were already constructed; nests made on fouled 

beaches are less likely to be affected, if at all. Residue oil may adhere to sand grains where eggs 

are deposited, later impeding hatchlings from successfully evacuating nests and ultimately leading to 

their death. Reproductive success could ultimately be impacted.

Hatchling and small juvenile turtles are particularly vulnerable to contacting or ingesting 

hydrocarbons because the currents that concentrate oil spills also form the debris mats in which 

young turtles are sometimes found (Carr, 1980; Collard and Ogren, 1990; Witherington, 1994). This 

would also be true for juvenile sea turtles that are sometimes found in floating mats of Sargassum. 

Oil slicks, slickets, or tarballs moving through offshore waters may foul Sargassum mats that 

hatchling and juvenile sea turtles inhabit, which would conceivably result in the loss of sea turtle 

habitat and/or incidental takes as defined under the ESA. High rates of oil contact in young turtles 

suggest that bioaccumulation may occur over their potentially long lifespan. The result of adult sea 

turtles feeding selectively in surface convergence lines could be prolonged contact with viscous 

weathered oil (Witham, 1978; Hall et al., 1983). Balazs (1985) and Gramentz (1988) found tar to be 

the most prevalent marine pollution ingested by sea turtles. However, more recent studies have 

shown contrary findings. Bjorndal et al. (1994) examined digestive tracts from 51 juvenile sea turtles 

in Florida and found only 1 (<2%) to have tar in the gut. Similarly, Bugoni et al. (2001) found that 

only 1 turtle out of 50 (approximately 2%) stranded turtles that were analyzed had ingested oil. 

Some captive sea turtles exposed to oil either reduced the amount of time spent at the surface,

possibly avoiding the oil, or became agitated and had short submergence levels (Lutcavage et al., 

1995). Sea turtles pursue and swallow tarballs, and there is no firm evidence that free-ranging 

turtles can detect and avoid oil (Odell and MacMurray, 1986). Therefore, oil might have a more 

indirect impact on the behavior of sea turtles.

OSRA Modeling

The OSRA modeling results, which show the probabilities of a large spill (≥1,000 bbl) 

occurring in Federal offshore waters making contact with State offshore waters, are provided in 

Figure E-20. In general terms, coastal waters of the area may be contacted by many, frequent, 
4-284 Gulf of Mexico Multisale EIS

small spills (≤1 bbl); few, infrequent, moderately-sized spills (>1 and <1,000 bbl); and a single large 

spill (≥1,000 bbl) as a result of a proposed action. Pipelines pose the greatest risk of a large spill 

occurring in coastal waters compared with platforms and tankers. Spill estimates over a 50-year 

time period are indicated in Table 3-17. According to Table 3-17, the majority of estimated spills 

would be small (<10 bbl). The actual number of spills that may occur in the future could vary from 

the estimated number. A spill size group for ≥10,000 bbl was not included in Table 3-17 because 

the catastrophic Deepwater Horizon oil spill (4.9 MMbbl released from the well) was the only spill in 

this size range during 1996-2010, and such a spill is not reasonably foreseeable in the future; thus, 

limited conclusions can be made from a single data point. For more information on OSRA, refer to 

Chapter 3.2.1.4 (Analysis of Offshore Spills ≥1,000 bbl).

Depending on the timing of a spill’s occurrence in coastal waters, its impact and resulting 

cleanup activities may interrupt sea turtle migration, feeding, mating, and/ or nesting activity for 

extended periods (i.e., days, weeks, or months). Spills originating in or migrating through coastal 

waters of Texas or Louisiana may impact any of the five sea turtle species inhabiting the GOM. 

Kemp’s ridley is the most endangered sea turtle species and is strongly associated with the coastal 

waters of Texas and Louisiana. Aside from the acute impacts noted if sea turtles encounter an oil 

slick, the displacement of sea turtles to less suitable habitats from habitual feeding areas impacted 

by oil spills may increase vulnerability to predators, disease, or mortality from anthropogenic causes. 

A high incidence of juvenile sea turtle foraging occurs along certain coastal regions of the Gulf 

Coast. The interruption of mating and nesting activities for extended periods could influence the 

recovery of sea turtle populations.

The likelihood that members of a sea turtle population (e.g., Kemp’s ridley) may encounter 

an oil slick resulting from a single spill during a 50-year period is greater than that of a single 

individual encountering a slick during its lifetime. It is impossible to estimate precisely what sea 

turtle species, populations, or individuals would be impacted, to what magnitude, or in what 

numbers, since each species has unique distribution patterns in the GOM and because of difficulties 

attributed to estimating when and where oil spills would occur over a 50-year period.

Given the distribution of available leases and pipelines associated with a proposed action 

and the distribution of sea turtles in the northern GOM, the fate of an oil spill must be considered 

relative to the region and period of exposure. Projected oil production is 0.211-1.118 BBO and 

0.547-4.424 Tcf of gas over 50 years. Chapter 3.2.1 details the persistence, spreading, and 

weathering process for offshore spills.

Sea turtles are vulnerable to oil and dispersants at all life stages (i.e., eggs, post-hatchlings, 

juveniles, sub-adults, and adults), and there is no demonstrated avoidance behavior (Shigenaka 

et al., 2010). Impacts to sea turtles from OCS oil- and gas-related accidental oil spills are expected 

to range from negligible to moderate depending on the timing, size, and location of the spill, as well 

as new technologies in place to lessen the possibility of an accidental event from occurring. A 

moderate impact would be a spill contacting an individual and causing injury or mortality.
Description of the Affected Environment and Impact Analysis 4-285

Spill-Response Activities

In addition to the impacts from contact with hydrocarbons, spill-response activities could 

adversely affect sea turtle habitat and cause displacement from suitable habitat. Impact-producing 

factors might include artificial lighting from night operations, booms, machine and human activity, 

increased vessel traffic (refer to the “Transportation” section under “Routine Activities” above), 

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 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 (Lutcavage 

et al., 1997). Increased human presence could influence turtle behavior and/or distribution, thereby 

stressing animals and making them more vulnerable to predators, the toxicological effects of oil, or 

other anthropogenic sources of mortality. The strategy for cleanup operations vary, depending on 

the season, recognizing that disturbance to the nest may be more detrimental than the oil (Fritts and 

McGehee, 1982). After passage of the Oil Pollution Act of 1990, seagrass beds and live bottom 

communities are expected to receive individual consideration during spill cleanup. Required spill 

contingency plans include special notices to minimize adverse effects from vehicular traffic during 

cleanup activities and to maximize protection efforts to prevent contact of these areas with spilled oil.

Little is known about the effects of dispersants on sea turtles and, in the absence of direct 

testing, impacts are difficult to predict. Dispersant components absorbed through the lungs or gut 

may affect multiple organ systems and interfere with digestion, excretion, respiration, and/or saltgland function. Inhalation of dispersant can interfere with function through the surfactant (detergent) 

effect. These impacts are likely similar to the empirically demonstrated effects of oil alone (Hoff and 

Shigenaka, 2003). The impacts to sea turtles from chemical dispersants could include nonlethal 

injury (e.g., tissue irritation, chemical burns, and inhalation), long-term exposure through 

bioaccumulation, infection, and potential shifts in distribution from some habitats (USDOC, NOAA, 

2015k; Shigenaka et al., 2010). For more information on dispersants, refer to Chapter 3.2.7.2

(Offshore Response, Containment, and Cleanup Technology).

Due to spill response and cleanup efforts, much of an oil spill may be recovered before it 

reaches the coast. However, cleanup efforts in offshore waters may result in additional harm or 

mortality of sea turtles, particularly to neonates and juveniles. Spill-response activities are expected 

to have minimal adverse effects on sea turtles based on the short exposure duration of the activities 

and are more likely to have a positive effect on sea turtles over time given the removal of spilled oil, 

turtle and nest relocation, and contact prevention efforts. Due to the nature of the response 

activities, minor impacts could occur by a behavioral change of sea turtles in the immediate area. 

Therefore, impacts from spill-response activities are expected to be negligible to minor. There are 

also mitigations and plans in place (e.g., from the USCG, BSEE, States, NMFS, FWS, NPS) to 

decrease impacts to sea turtles.
4-286 Gulf of Mexico Multisale EIS

Cumulative Impacts

This cumulative analysis considers the effects of impact-producing factors related to a 

proposed action along with impacts of other commercial, military, recreational, offshore, and coastal 

activities that may occur and adversely affect populations of sea turtles in the same general area of 

a proposed action.

OCS Oil- and Gas-Related Impacts

The major impact-producing factors resulting from cumulative OCS energy-related activities 

associated with a proposed action that may affect GOM sea turtles and their habitats include those 

already described under “Routine Activities” and “Accidental Events” sections above, i.e., geological 

and geophysical activities, transportation, discharges, marine debris, decommissioning, noise, and 

accidental oil spills and spill response. Chapters providing supporting material for the sea turtle 

analysis include Chapters 4.1 (Air Quality), 4.2 (Water Quality), 4.3 (Coastal Habitats), 

4.4 (Deepwater Habitats), 4.5 (Sargassum and Associated Communities), 3.1 (Offshore ImpactProducing Factors and Scenario), 3.1.7 (Transport), 3.1.9 (Decommissioning), and 5.7 (Endangered 

Species Act). The cumulative impact of these ongoing OCS energy-related activities on sea turtles 

is expected to result in a number of chronic and sporadic sublethal effects (i.e., behavioral effects 

and nonfatal exposure to or intake of OCS oil- and gas-related contaminants or discarded debris) 

because these activities may stress and/or weaken individuals of a local group or population and 

may predispose them to infection from natural or anthropogenic sources.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related impact-producing factors that may affect sea turtle populations 

include: accidental oil spills and response (State oil and gas), vessel traffic, commercial fishing (i.e., 

bycatch and entanglement), dredging and construction, habitat loss, historic overexploitation (that 

led to the initial listing of the species), marine trash and debris, military operations, natural 

phenomena including disasters and climate change, noise ( i.e., from commercial fishing, 

recreational vessels, military activities, commercial shipping, tourism, construction), 

pathogens/disease, scientific research, and transportation and related noise (e.g., commercial 

shipping and research vessels). With the exception of BOEM’s Marine Minerals Program, BOEM 

does not regulate any of the aforementioned non-OCS oil- and gas-related activities, though some 

may be mitigated/regulated by other agencies. The factors that may have the largest impacts to sea 

turtles are outlined below.

The Gulf Coast is a well-populated and growing area, and development of previously 

unusable land for residential and commercial purposes is common. Increased human activity along 

the coast and offshore results in increased runoff and dumping. Many areas around the GOM 

already suffer from high contaminant levels due to river and coastal runoff and discharges. 

Contaminants may accumulate in species or in prey species. Sea turtles frequent coastal habitats to 

seek food (such as sponges, jellyfish, crabs, or seagrass) and shelter (Bjorndal, 1997). Coastal 

areas are also used by juvenile and adult Kemp’s ridleys in Louisiana (Ogren, 1989; Shaver et al., 
Description of the Affected Environment and Impact Analysis 4-287

2013). Submerged areas of vegetation may be lost or damaged by activities (e.g., dredging) that 

alter salinity, turbidity, or natural tidal and sediment exchange.

Accidental oil spills and spill response by State oil and gas activities could occur, and 

impacts would be similar to those described above for OCS oil- and gas-related activities. Impacts 

would be mainly dependent on the size and location of the spill, although State oil and gas activities 

are located in shallow waters closer to the coast, so there may be an increased potential for oil 

contacting the coastline. Naturally occurring seeps may also be a source of oil that contacts the 

coast. 

Numerous commercial and recreational fishing vessels use areas in the northern GOM. 

Tanker imports and exports of crude and petroleum products into the GOM are projected to 

increase. Crude oil would continue to be transported to the Gulf for refining from other areas of the 

United States (i.e., Alaska, California, and the Atlantic). Recreational pursuits can have an adverse 

effect on sea turtles through propeller and boat strike damage. Areas closer to shore where sea 

turtles regularly migrate through, mate, nest, and forage (Shaver et al., 2013; Hart et al., 2010 and 

2012) may have an elevated likelihood of vessel strikes or avoidance to aircraft, due to increased 

transportation in those areas.

Sea turtle bycatch in the GOM is high, specifically for the longline fishery, and can be driven 

by turtle density, fishing intensity or both (Lewison et al., 2014). For example, the chief areas used 

by Kemp’s ridleys (coastal waters <59 ft [18 m] in depth) overlap with the shrimp fishery (Renaud, 

1995; Shaver et al., 2013). A major source of mortality for loggerhead and Kemp’s ridleys is capture 

and drowning in shrimp trawls (Caillouet et al., 1996; Epperly and Teas, 2002; Shaver et al., 2013; 

USDOC, NMFS and USDOI, FWS, 2015), which accounts for most (up to 98%) of the sea turtle 

bycatch in the U.S. (Finkbeiner et al., 2011). Crowder et al. (1995) reported that 70-80 percent of 

turtle strandings were related to interactions with this fishery. Caillouet et al. (1996) found a 

significant positive correlation between turtle stranding rates and shrimp fishing intensity in the 

northwestern GOM. The Kemp’s ridley population, because of its distribution and small numbers, is

at greatest risk. To lessen fishery impacts to turtles, the NMFS has required the use of turtle 

excluder devices in southeast U.S. shrimp trawls since 1989 and has increased efforts over the 

years for adequate protection to decrease the number of strandings. The use of turtle excluder 

devices was believed to reduce hard-shelled sea turtle captures by 97 percent; however, evidence 

has shown that a large proportion of turtles are too big to fit through the openings (Epperly and Teas, 

2002). Since implementing the required use of turtle excluder devices throughout the shrimp fishing 

industry, gear improvements continue to be introduced nearly annually. Turtles may be accidentally 

caught and killed in finfish trawls, seines, gill nets, weirs, traps, longlines, and driftnets (Witzell, 

1992; Brady and Boreman, 1994; Epperly and Teas, 2002; USDOC, NMFS and USDOI, FWS, 

2013a and 2013b). Florida and Texas have banned all but very small nets in State waters. 

Louisiana, Mississippi, and Alabama have also placed restrictions on gillnet fisheries within State 

waters, such that very little commercial gillnetting takes place in southeast waters. The State fishery 

for menhaden in the State waters of Louisiana and Texas is managed by the Gulf States Marine 
4-288 Gulf of Mexico Multisale EIS

Fisheries Council and is not federally regulated for sea turtle take. Fishery interactions with sea 

turtles remain a major source of mortality.

Dredge-and-fill activities occur in many of the coastal areas inhabited by sea turtles and can 

create impacts, but agencies permitting these activities must consult on the ESA and protective 

measures would be required to prevent adverse impacts. Operations range in scope from propeller 

dredging (scarring) by recreational boats to large-scale navigation dredging and fill for land 

reclamation. Dredging operations affect turtles through incidental take (entrainment) and habitat 

degradation (Michel et al., 2013b). The construction and maintenance of Federal navigation 

channels, as well as dredging offshore sand resource areas (i.e. borrow areas) to support coastal 

restoration and beach nourishment projects, have been identified as sources of sea turtle mortality. 

Hopper dredges can entrain and kill individuals, presumably either by catching sea turtles 

resting/foraging on the bottom or as the drag arm of the moving dredge overtakes a slower-moving 

animal. Hopper dredging has caused turtle mortality in coastal areas (Slay and Richardson, 1988). 

Nearly all sea turtles entrained by hopper dredges are dead or dying when found (NRC, 1990). 

However, there continues to be engineering of modified turtle excluding devices for hopper dredges 

to reduce entrainment (Henriksen et al., 2015). In addition to direct take, channelization of the 

inshore and nearshore areas can degrade foraging and migratory habitats via spoil dumping, 

degraded water quality/clarity, and altered current flow.

Construction, beach front development, beach vehicle traffic, beach erosion, nest predation, 

and artificial lighting are activities that disturb sea turtles or their nesting beaches (Garber, 1985; 

Conant et al., 2009). Vehicles and beach cleaning activities may crush nests, reducing hatching 

success (Coston-Clements and Hoss, 1983). Physical obstacles, such as deep tire tracks and 

expanded sand piles, may obstruct hatchling turtles from entering the sea or increase their stress 

and susceptibility to predation (Witham, 1995). Obstructions to the high watermark prevent nesting, 

and breakwalls are the most common and severe type of obstruction. Erosion can result in the loss 

of habitat, and artificial lighting affects nesting beaches. Human interference has hastened erosion 

in many places. Artificial lighting from buildings, street lights, and beachfront properties may 

disorient hatchlings, as well as adults (Witherington and Martin, 1996). Females tend to avoid areas 

where beachfront lighting is most intense; turtles also abort nesting attempts more often in lighted 

areas. Hatchlings are attracted to lights and may become disoriented, increasing their vulnerability 

to terrestrial predators. As part of NRDA’s early restoration efforts, there is a project focused on 

restoring the night sky or identifying and reducing artificial lighting on shorelines. Details on the 

project can be found on NOAA’s Habitat Conservation website (USDOC, NOAA, 2016b). 

Condominiums sometimes block sunlight on nesting beaches, which could presumably affect sex 

ratios of hatchlings (the sex of a turtle is dependent on egg temperature) by increasing the number 

of males produced (Mrosovsky et al., 1995). Increased human activities, such as organized turtle 

watches, on nesting beaches may adversely affect nesting activity (Fangman and Rittmaster, 1994; 

Johnson et al., 1996). Species that prey on sea turtle nests include fire ants, raccoons, armadillos, 

and opossums. Sea turtles entering coastal or inshore areas have been affected by entrainment in 

the cooling water systems of electrical generating plants (NRC, 1990). Deaths can result from 

injuries sustained in transit through the intake pipe, from drowning in capture nets, and perhaps from 
Description of the Affected Environment and Impact Analysis 4-289

other causes before entrainment (Bressette et al., 1998). Thermal effluents from power plants may 

cause hatchlings to become disoriented and reduce their swimming speed (O’Hara, 1980). These 

effluents may also degrade important foraging seagrass and reef habitats (Coston-Clements and 

Hoss, 1983). It has been suggested that power plants could also provide positive impacts by 

providing warm-water refuge in some areas (McDonald et al., 1994; Turner-Tomaszewicz and 

Seminoff, 2012).

Sand mining, beach nourishment, and oil-spill cleanup operations may remove sand from the 

littoral zone and temporarily disturb onshore sand transport, potentially disturbing nesting activities. 

BOEM has evaluated the use of sand resources for levee, beach, and barrier island restoration 

projects. For more than 20 years, BOEM has provided over 112 million yd3 (85 million m3

) of OCS 

sand for 40 coastal projects, restoring over 269 mi (433 km) of national coastline. As the demand for 

sand for shoreline protection and restoration increases, OCS sand and gravel has become an 

increasingly important resource. Use of these resources would require coordination with BOEM for 

appropriate authorization. Sea turtles are included in the potential impacts identified for sand 

dredging projects. Mitigating measures include requiring stipulations to protect sea turtles when it is 

determined that there is a likelihood of sea turtle presence within the area during the dredging 

operation, and a trailing suction hopper dredge is used. As part of NRDA’s early restoration efforts, 

there are at least three artificial reef projects totaling $7.7 million in the GOM that would provide 

more shelter and feeding habitat for turtles. Details on these projects can be found on NOAA’s 

website (USDOC, NOAA, 2016c).

Explosive discharges, such as those used for COE structure removals or coastal 

construction, can cause injury to sea turtles (Duronslet et al., 1986), but they are subject to ESA 

consultation with the NMFS. Although sea turtles far from the site may suffer only disorientation, 

those near detonation sites could sustain fatal injuries. Injury to the lungs, intestines, and/or auditory 

system could occur. Other potential impacts include physical or acoustic harassment. 

Resuspension of bottom sediments, increased water turbidity, and mobilization of bottom sediments 

due to explosive detonation are considered to be temporary effects.

Historically, sea turtles were overexploited by the poaching of eggs and individuals, and with 

the added pressures of other historic non-OCS oil- and gas-related impact-producing factors 

described in this section (e.g., commercial fishing), the NMFS determined there was a need to list 

them under the ESA. Human consumption of turtle eggs, meat, or byproducts still occurs worldwide 

and depletes turtle populations (Conant et al., 2009; USDOC, NMFS and USDOI, FWS, 2007b and 

2013b). Commercial harvests are no longer permitted within continental U.S. waters, and Mexico 

has banned such activity (Aridjis, 1990).

Chronic pollution, including industrial and agricultural wastes and urban runoff, threatens sea 

turtles worldwide (Frazier, 1980; Hutchinson and Simmonds, 1991). Some turtle species have 

lifespans exceeding 50 years (Congdon, 1989; Frazer et al., 1989) and are secondary or tertiary 

consumers in marine environments, creating the potential for bioaccumulation of heavy metals, 

pesticides, and other contaminants (Davenport et al., 1990; Lutz and Lutcavage, 1989) in their 
4-290 Gulf of Mexico Multisale EIS

tissues. Organochlorine pollutants (pesticides) have been documented in eggs, juveniles, and adult 

turtles (Rybitski et al., 1995). The DDE from DDT is the pesticide present in the greatest 

concentrations in sea turtles (Camacho et al., 2013). Contaminants could stress the immune system 

of sea turtles or act as carcinogens indirectly by disrupting neuroendocrine functions (Colborn et al., 

1993; Camacho et al., 2012).

Numerous sources of aircraft fly over the coastal and offshore areas and create noise that 

may cause behavioral responses in sea turtles as described in the “Noise” section above. The air 

space over the GOM is used extensively by DOD for conducting various air-to-air and air-to-surface 

operations. Eleven military warning areas and five water test areas are located within the GOM, as 

stated in NTL 2014-BOEM-G04, “Military Warning and Water Test Areas” (Figure 2-7). Additional 

activities, including vessel operations, discharges associated with military activities, and ordnance 

detonation, also may affect sea turtles. Subject to the Federal Aviation Administration’s guidelines, 

private and commercial air traffic further traverse these areas and have the potential to cause 

impacts to sea turtles.

Natural catastrophes, including storms, floods, droughts, and hurricanes, can also 

substantially damage nesting beaches and coastal areas used by sea turtles (Agardy, 1990; Fish 

et al., 2015). Abnormally high tides and waves generated by storms may exact heavy mortality on 

sea turtle nests by washing them from the beach, inundating them with sea water, or altering the 

depth of sand covering them. Furthermore, excessive rainfall associated with tropical storms may 

reduce the viability of eggs. Turtles could be harmed in rough seas by floating debris (Milton et al., 

1994). In addition, the hurricane season for the Caribbean and Western Atlantic (June 1 through 

November 1) overlaps the sea turtle nesting season (March through November) (NRC, 1990). Nests 

are vulnerable to hurricanes during the incubation period as well as when hatchlings evacuate the 

nest. Hurricanes can cause mortality at turtle nests through immediate drowning from ocean surges, 

nest burial, or exhumation before hatching, and after hatching as a result of radically altered beach 

topography. Natural phenomena could result in numerous impacts to sea turtles as well. Rising sea 

levels could further diminish available nesting beach habitat. Changing ocean temperatures may 

alter distribution patterns for sea turtle prey (i.e., jellyfish for leatherbacks). This could impact adult 

survivability as well as nesting success. Warming temperatures may change the sex ratios of 

hatchlings as sex is determined by nest temperature. Larger, more frequent storms can physically 

impact nesting beaches. These are just a few examples of potential effects of global climate change 

(Intergovernmental Panel on Climate Change, 2016).

Noise from non-OCS oil- and gas-related activities may impact sea turtles and is described in 

Chapter 3.3.2.8. Areas closer to shore normally have higher noise levels (more human-use), and 

levels typically drop off moving into deeper water. Non-OCS noise sources include, but are not 

limited to, commercial fishing vessels, recreational vessels, scientific vessels, tourism vessels and 

watercraft, military operations, lightning, aircraft, State oil and gas activities, etc. Sea turtles have a 

high potential for recoverable injury from temporary hearing loss (i.e., temporary threshold shift) and 

behavioral modifications only when they are close in proximity to the source. Mortality and injury 

caused by shipping and continuous noise are expected to have low levels of relative risk even if a 
Description of the Affected Environment and Impact Analysis 4-291

sea turtle is relatively near the source. The risk for temporary threshold shift near the source is 

moderate, while the risk for masking may be high both at near and intermediate distances from the 

source, and the risk for behavioral modifications near the source are high and moderate at 

intermediate distances from the source. Effects from sound are relative to the source type, distance 

to the source, frequency, intensity and duration of the source, and distance to the animal.

Sea turtles are affected by pathogens and disease, which may be secondary infections 

following other stressors, such as an entanglement injury or nutritional deficiencies. Some of these 

diseases are described in the affected environment and include fibropapillomatosis (believed to be 

caused by a herpes virus); viral, bacterial, and mycotic (fungal) infections; parasites (internal or 

external); and other environmental health problems (e.g., hypothermic stunning). Van Houtan et al. 

(2014) found fibropapillomatosis could be linked, at least in part, to eutrophication.

Scientific research may impact sea turtles. Many studies require the attachment of 

equipment to turtle shells that could reduce fitness, and often turtles must be caught and/or held 

captive for a period of time before being released back into their natural environment. This could 

cause stress to a turtle; however, research is typically seen as an overall positive impact due to 

learning more about life histories of turtles and, therefore, allowing for better species management. 

The incremental contribution to cumulative impacts on sea turtles, even when taking into 

consideration the potential impacts of the Deepwater Horizon explosion, oil spill, and response, nonOCS oil- and gas-related factors and the minimization of OCS oil- and gas-related impacts through 

lease stipulations and regulations, would be expected to be negligible as a result of a proposed 

action.

Incomplete or Unavailable Information

Unavailable information, such as impacts following an oil-spill response and the population 

variation due to naturally occurring events such as hurricanes and heightened stranding numbers, 

provides challenges in understanding the baseline conditions and changes within sea turtle 

populations. As previously discussed, the impacts of tropical storms and hurricanes in the GOM, 

and on the listed species and critical habitat in particular, have never been determined and, 

ultimately, the impacts remain very difficult to quantify. Unavailable information on the impacts 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 impacts 

less defined. The Deepwater Horizon NRDA Trustee Council has released the Deepwater Horizon 

Oil Spill Draft Programmatic Damage Assessment and Restoration Plan and Draft Programmatic 

Environmental Impact Statement. However, the information collected during the NRDA process that 

the draft assessment, plan, and EIS used as a basis for their determinations are not yet publicly 

available (e.g., NRDA technical working group reports). The final plan may address much of what 

has been currently unavailable with regard to impacts to the environment from the Deepwater 

Horizon explosion, oil spill, and response. The status of sea turtle populations after the Deepwater 

Horizon explosion, oil spill, and response remains unclear and may be difficult or impossible to 

discern from other factors. BOEM used existing information and reasonably accepted scientific 
4-292 Gulf of Mexico Multisale EIS

methodologies to extrapolate from publicly available information on sea turtles in completing the 

relevant analysis of sea turtle populations.

There are existing leases in the GOM with ongoing or the potential for exploration, drilling, 

and production activities. In addition, non-OCS oil- and gas-related activities would continue to 

occur in the GOM irrespective of a proposed action (e.g., fishing, military activities, and scientific 

research). Sea turtles that may occur in the GOM and within areas affected by the spill are unlikely 

to have experienced population-level impacts from the Deepwater Horizon explosion, oil spill, and 

response given their wide-ranging distribution and behaviors. Therefore, 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, but BOEM has 

determined that the information is not essential to a reasoned choice among alternatives for this 

Multisale EIS (including the No Action and Action Alternatives). 

4.9.2.2.1 Alternative A, B, C, and D

With respect to sea turtles, the effects associated with selection of any of the action 

alternatives would be equivalent because of the diversity and distribution of sea turtles throughout 

the potential Area of Interest. The preceding analyses assumed a wide distribution of species and 

considered impacts to sea turtles occurring in a wide range of habitats across all planning areas. 

While the WPA is a smaller area with less projected activity than is proposed for the CPA/EPA (refer 

to Chapter 3), sea turtles are widely distributed throughout the planning areas. As such, activities 

isolated to specific planning areas pose similar potential impacts to populations as do activities 

occurring in all planning areas. Therefore, a similar mix of species would be exposed to the 

analyzed impact-producing factors, regardless of the specific action alternative selected. The 

activities proposed under Alternatives A, B, C, and D would directly impact sea turtles within the 

GOM and would contribute incrementally to the cumulative effects on these species.

Sea turtles of all five species are present throughout the northern GOM; however, only 

Kemp’s ridley and loggerheads nest on beaches in the GOM. Individual animals make migrations 

into nearshore waters as well as other areas of the Gulf of Mexico, Atlantic Ocean, and the 

Caribbean Sea. Historically, intense harvesting of eggs, loss of suitable nesting beaches, and 

fishery-related mortality led to rapid declines of sea turtle populations.

Anthropogenic actions continue to pose the greatest threat to sea turtles. Ingestion of ocean 

debris and entanglement in nondegradable debris such as trash and discarded fishing gear continue 

to pose threats and lead to turtle deaths each year. Young turtles in their pelagic phase are 

dependent on ocean driftlines for habitat and food (Witherington et al., 2012). Young turtles feeding 

in driftlines have been documented to ingest plastics, styrofoam, balloons, and tar; mortalities have 

been attributed to ingestion of plastics and tar (Witherington et al., 2012; Carr, 1987b; Witham, 

1978).
Description of the Affected Environment and Impact Analysis 4-293

Sea turtles are adversely impacted by many fisheries activities, including trawl fisheries, 

gillnet fisheries, hook-and-line fisheries, pelagic longline fisheries, pound nets, fish traps, lobster 

pots, whelk pots, long-haul seines, and channel nets. The NMFS continues to modify the turtle 

excluder device design to reduce sea turtle mortality in trawl fisheries. Sea turtles entangled in 

fishing gear generally have a reduced ability to feed, dive, surface to breathe, or perform any other 

activities that are essential to survival (Balazs, 1985). They may be more susceptible to boat strikes 

if they are forced to remain at the surface, and entangling lines can constrict blood flow, resulting in 

necrosis and potential loss of limbs.

Declines in sea turtle populations also result from nonfishery impacts, such as power plant 

intakes; marine pollution; direct harvesting of eggs and adults in foreign countries; oil and gas 

exploration, development, and transportation; underwater explosions; dredging; offshore artificial 

lighting; marina and dock construction and operation; boat collisions; and poaching. Sea turtle 

critical habitat and nesting sea turtles are threatened with climate change, natural disasters, beach 

erosion, armoring, nourishment, artificial lighting, beach driving and cleaning, increased human 

presence, human response to disasters, coastal development, recreational beach use including 

equipment and furniture, exotic dune and beach vegetation, natural habitat obstructions, military 

testing and training activities, poaching, and nest predation.

Although there would always be some level of incomplete information relevant to the impacts 

from activities under a proposed action on GOM sea turtles, BOEM does not believe it is essential to 

a reasoned choice among alternatives. To date, there is no peer-reviewed scientific information 

available supporting that any impacts expected from a proposed action would be expected to rise to 

the level of reasonably foreseeable population-level impacts. BOEM acknowledges that impacts 

from routine activities or accidental events could be greater on individuals or populations already 

affected by other OCS oil- and gas-related or non-OCS oil- and gas-related impact-producing 

factors. Nevertheless, routine activities are ongoing in a proposed action area as a result of active 

leases and related activities. Further, activities that could result in an accidental spill in the GOM 

would be ongoing whether or not a proposed action occurred.

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 

compliance with NTL 2012-JOINT-G01 (“Vessel-Strike Avoidance and Injured/Dead Protected 

Species Reporting”) and NTL 2015-BSEE-G03 (“Marine Trash and Debris Awareness Elimination”), 

as well as the limited scope, timing, and geographic location of a proposed action, would result in a 

minimized impact from a 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 

mitigations include onboard observers, airgun shut-downs for whales in the exclusion zone, ramp-up 

procedures, and the use of a minimum sound source.

Because of the mitigations (e.g., BOEM and BSEE’s proposed compliance with NTLs) 

described above, routine activities and accidental events related to a proposed action are not 
4-294 Gulf of Mexico Multisale EIS

expected to have long-term adverse effects on the size and productivity of any sea turtle species or 

populations in the northern GOM. Lethal impacts could occur from chance collisions with OCS 

service vessels or ingestion of accidentally released plastic materials from OCS vessels and 

facilities, which would be considered moderate impacts. However, there have been no reports to 

date on such incidences. Most OCS oil- and gas-related routine activities and accidental events are 

then expected to have negligible impacts. 

BOEM is unable to determine at this time, based on best available science, what impact the 

Deepwater Horizon explosion, oil spill, and response had on sea turtles. Further, the data on the 

impacts may still take years to acquire and analyze to make those determinations. Impacts from the 

Deepwater Horizon explosion, oil spill, and response may be difficult or impossible to discern from 

other factors. While the impact-producing factors associated with a proposed action could 

potentially impact sea turtles if unmitigated, the incremental contribution to cumulative impacts on 

sea turtles, even when taking into consideration the potential impacts of the Deepwater Horizon

explosion, oil spill, and response, non-OCS oil- and gas-related factors and the minimization of OCS 

oil- and gas-related impacts through lease stipulations and regulations, would be expected to be 

negligible as a result of a proposed action. Within the GOM, there is a long-standing and welldeveloped OCS Program (more than 50 years), and population-level impacts to sea turtles are not 

anticipated.

4.9.2.2.2 Alternative E—No Action

Under Alternative E, there would be no lease sale held and therefore no postlease activities 

related to such a lease sale to impact sea turtles. However, there would be continuing impacts to 

sea turtles related to previous OCS oil- and gas-related development and non-OCS oil- and gasrelated activities. Sea turtles move in the GOM over great spatial scales and they would be 

expected to move in and out of the previously leased blocks. In addition, many of these blocks 

already have OCS oil- and gas-related development, and sea turtles would continue to be impacted 

by routine activities and accidental events from pre-existing OCS development.

4.9.3 Beach Mice (Alabama, Choctawhatchee, Perdido Key, and St. Andrew)

The following four subspecies of beach mouse (Peromyscus polionotus) occupy restricted 

habitats in the mature coastal dunes of Florida and Alabama and are federally listed as endangered: 

Alabama (P.p. ammobates), Perdido Key (P.p. trisyllepsis), and Choctawhatchee (P.p. allophrys) 

subspecies (listed June 6, 1985) (Federal Register, 2006b) and St. Andrew (P.p. peninsularis) 

subspecies (listed December 18, 1998) (Federal Register, 1998). Current critical habitat is included 

in the critical habitat map (Figure 4-23). Populations of the listed subspecies have fallen to levels 

approaching extinction. These four subspecies of beach mice are similar in appearance but can be 

identified by pelage color and location (Bowen, 1968). The approach of this analysis is to focus on 

the potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., 

exploration, development, and production), as well as accidental events and cumulative impacts, 

and to define impact-level measures for each impact-producing factor (refer to Table 4-13 in 

Chapter 4.9).
Description of the Affected Environment and Impact Analysis 4-295

4.9.3.1 Description of the Affected Environment

Beach mice are restricted to the coastal barrier sand dunes along coastal Alabama and the 

Florida panhandle, and they are nocturnal herbivores that forage on sea oats and beachgrass but 

may occasionally consume invertebrates (Ehrhart, 1978; Moyers, 1996). For a detailed description 

of dunes, refer to Chapter 4.3.2.1 (Coastal Barrier Beaches and Associated Dunes, “Description of 

the Affected Environment”). Optimal overall beach mouse habitat is currently thought to be 

comprised of a heterogeneous mix of interconnected habitats including frontal dunes, scrub (tertiary) 

dunes farther inland, and interdunal areas between these dune habitats. Beach mice dig burrows 

mainly in the frontal dunes and interior scrub dunes where the vegetation provides suitable cover. 

Their burrows are important for avoiding predators, storing food, and providing cover during the day 

and inclement weather conditions.

Critical habitat for the four subspecies of beach mouse extend from Baldwin County, 

Alabama, to Gulf County, Florida. The beach and dunal areas that are associated with beach 

mouse habitat include the coastal regions associated with the CPA and EPA. Complete descriptions 

of current critical habitat can be found in USDOI, FWS (2010a) and Figure 4-23. Due to the 

dynamic nature of mouse populations that fluctuate with environmental conditions, abundance 

estimates are unreliable and trends are determined using percent area occupied. Efforts to monitor 

this metric are ongoing for each of the beach mouse subspecies.

4.9.3.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from the activities described in 

Chapter 3 that are associated with non-OCS and OCS oil- and gas-relate activities. This analysis 

applies to all considered alternatives. Because of the diversity and distribution of species in the Area 

of Interest, the level of impacts would be the same generally for Alternatives A, B, and D. Alternative 

C would have no impacts since no beach mice habitat is near the WPA proposed lease sale area. 

However, Alternative E, No Action, would only have impacts associated with the continuing impacts 

from past lease sales and non-OCS oil- and gas-related activities. Following the environmental 

consequences chapter, there is a summary of the potential impacts as they relate to the action 

alternatives.

Routine Activities

The major impact-producing factors associated with routine activities that may affect beach 

mice include activities that could occur in their habitat include marine trash and debris (Chapter 

3.1.5.3.4) and pipeline emplacement and construction (Chapters 3.1.3.3 and 3.1.4.1).

Impacts to beach mice may occur directly to the animal or its habitat. Marine trash and 

debris could affect beach mice due to the potential to ingest and/or become entangled. The BSEE 

has addressed the marine debris issue by imposing marine debris awareness and prevention 

measures on the oil and gas industry through NTL 2015-BSEE-G03 (formerly NTL 2012-BSEE-
4-296 Gulf of Mexico Multisale EIS

G01), which provides guidance to industry operators regarding the reduction of trash and debris 

elimination into the marine environment and informs operators of regulations set by other regulatory 

agencies (i.e., USEPA and USCG). Historically, NTL 2015-BSEE-G03 has been made a binding 

part of leases through the Protected Species Stipulation. The OCS oil- and gas-related proposed 

activities may contribute minimal marine debris or disruption to beach mouse areas, but the impacts 

would be negligible. Due to the proximity of the beach mouse habitat to any OCS oil- and gasrelated activity, any debris as a result of OCS oil- and gas-related activities would not likely reach 

beach mouse habitat.

Pipeline emplacement or construction for routine activities could cause temporary 

degradation of beach mouse habitat, but it is not likely to occur in areas of designated critical habitat. 

Pipelines and construction would not be expected in the vicinity of beach mouse habitat; the impacts 

from pipeline emplacement and coastal construction associated with routine activities would 

therefore be negligible. For more information on the associated impacts of routine activities on the 

larger scale of the beach environment, refer to Chapter 4.3.2.2 (Coastal Barrier Beaches and 

Associated Dunes, “Environmental Consequences").

Accidental Events

The major impact-producing factors resulting from accidental events reasonably expected to 

be associated with the OCS oil- and gas-related activities that may affect beach mice include coastal 

and offshore oil spills and spill-response activities.

Direct contact with spilled oil can cause skin irritation and/or cause the fur to mat, resulting in 

the loss of its insulative properties for thermoregulation. Other direct toxic impacts may result from 

oil ingestion, absorption, or respiratory effects from the inhalation of fumes. Indirect impacts may 

include contamination and depletion of food supply, destruction of habitat, and fouling of burrows. 

There is no definitive information on the persistence of oil in the event that a spill was to contact 

beach mouse habitat. In Prince William Sound, Alaska, after the Exxon Valdez spill in 1989, buried 

oil has been measured in the intertidal zone of beaches, but no effort has been made to search for 

residual buried oil above high tide. Similarly, NRC (2003) makes no mention of studies of oil left 

above high tide after a spill. Regardless of the potential for persistence of oil in beach mouse 

habitat, a slick cannot wash over the foredunes unless carried by a heavy storm swell. The oiling of 

beach mouse populations could result in local extinction, but this is unlikely given that the chance of 

a spill occurring and contacting the habitat is between <0.5 and 1 percent after 10 or 30 days of a 

spill, and the area of viable habitat is broad relative to the area potentially contacted by a large spill 

according to the OSRA model (refer to Chapter 3.2.1.5).

Impacts can also occur from spill-response activities. Vehicle traffic and other activities 

associated with oil-spill cleanup can degrade preferred habitat and crush burrows, resulting in 

displacement of mice from these areas. These impacts could be reduced if personnel are properly 

trained to identify and avoid sensitive habitat (which may be on short notice if under emergency 

conditions). Impacts from an accidental oil spill and cleanup efforts would be negligible. For more 
Description of the Affected Environment and Impact Analysis 4-297

information on habitat impacts from accidental events, refer to Chapter 4.3.2.3 (Coastal Barrier 

Beaches and Associated Dunes).

Cumulative Impacts

This cumulative analysis considers factors that affect beach mice, including oil spills, 

alteration and reduction of habitat, predation (especially from feral or free-roaming domestic cats) 

and competition, ingestion and entanglement of beach trash and debris, beach development, coastal 

spills, and natural catastrophes (i.e., hurricanes and tropical storms).

OCS Oil- and Gas-Related Activities

Oil spills that are related to the importing and transporting of oil resulting from prior and 

future lease sales are not expected to contact beach mice or their habitats because the species lives 

above the intertidal zone where contact is less likely. For more information on impacts to the dune 

habitat, refer to Chapter 4.3.2.3 (Coastal Barrier Beaches and Associated Dunes). Therefore, the 

expected incremental contribution of OCS oil- and gas-related activities to the cumulative impacts is 

negligible, given the proximity of beach mouse habitat and the relatively small likelihood that a 

reasonably foreseeable spill would reach their habitat.

Non-OCS Oil- and Gas-Related Activities

The greatest impacts to beach mice are based on impacts to their habitat. Non-OCS oil- and 

gas-related activities may also incur negative impacts to the habitat or directly by interactions with 

other species. Cumulative impacts from coastal development, State oil and gas activities, predation, 

recreational beach use, trash and debris, disease, hurricanes, and the effects of global climate 

change may affect the protected subspecies of beach mice. For a full list of cumulative impacts to 

beach habitat, refer to Chapter 4.3.2 (Coastal Barrier Beaches and Associated Dunes).

Habitat Alteration and Reduction

Coastal development is the greatest threat to beach mouse survival. Habitat reduction and 

fragmentation have affected the ability of beach mice to quickly recover following tropical storms. 

Habitat fragmentation also reduces genetic diversity by limiting gene flow within contiguous habitat. 

Critical habitat provides an area of protected refugia for these subspecies of beach mouse and is 

important to sustain each population.

Predation and Competition

Non-native predators such as red fox and domestic cats pose a threat to beach mice. Feral 

cats may pose one of the greatest threats to beach mice (Bowen, 1968; Humphrey and Barbour, 

1981; Moyers, 1996). Gore and Schaeffer (1993) showed a significant correlation between the 

presence of cat tracks and beach mouse tracks on Santa Rosa Island. Predation by cats in 

conjunction with other threats may result in significant adverse impacts to beach mice (Federal 

Register, 1998). The recovery plans for these four subspecies of beach mice include a component 
4-298 Gulf of Mexico Multisale EIS

of managing feral and free-ranging cats near beach mouse habitat by educating the public and 

control measures to eliminate feral cat populations near dune habitats. Predation and competition is 

a serious concern for beach mice with impacts to populations. The cumulative impacts are 

negligible to major

Hurricanes

Population viability analysis is essentially a demographic modeling exercise to predict the 

likelihood that a population would continue to persist over time (Groom and Pascual, 1998). The 

objective of a population viability analysis for beach mice is to determine how large and what 

configuration of habitat is necessary to reasonably assure that the species would survive to recover. 

The most recently revised model, which includes data from hurricanes, projects a risk of extinction of 

26.8 ± 1.0 percent over the next 100 years. Falcy (2011) used modeling to show recovery of 

Alabama beach mouse populations during the 4 years after Hurricane Ivan (2004) and Hurricane 

Katrina (2005). Further modeling showed that increasing the rate of population growth in a refuge, 

like interior dunes after a hurricane, would have a much larger impact on population persistence than 

increasing the rate of recovery of damaged habitat, like foredunes after a hurricane. Yuro (2011) 

studied Hurricanes Ivan and Katrina and showed that the Alabama beach mouse has the ability to 

survive hurricanes if they are not successive. Therefore, the expected incremental contribution of 

strong hurricanes is negligible.

Incomplete or Unavailable Information

BOEM has determined that there is no incomplete or unavailable information regarding the 

listed beach mice relevant to the potential impacts from a proposed action or alternatives, and no 

such information was essential to a reasoned choice among alternatives. BOEM used existing 

information and reasonably accepted scientific methodologies to extrapolate from available 

information on beach mice in completing the relevant analysis of impacts.

4.9.3.2.1 Alternative A—Regionwide OCS Proposed Lease Sale (The Preferred Alternative)

An impact from the OCS oil- and gas-related routine activities associated with a proposed 

action (i.e. proposed regionwide lease sale) on the Alabama, Choctawhatchee, St. Andrew, and 

Perdido Key beach mice is possible but unlikely. Impacts may result from ingestion or entanglement 

in beach trash and debris that could be accidentally lost, despite mitigations typically applied through 

the lease and NTLs. Because OCS oil- and gas-related routine activities would deposit only a small 

portion of the total debris that would reach the habitat, the impacts related to a proposed lease sale 

under Alternative A would be negligible. 

The oiling of beach mouse populations caused by one or more of the reasonably foreseeable 

accidental events as a result of a proposed action could result in local extinctions. Oil-spill response 

and cleanup activities could also have a substantial impact to beach mice and their habitat if all 

cleanup personnel are not adequately trained to avoid areas where beach mouse burrows are 

present. However, potential spills that could result from OCS oil- and gas-related activities are not 
Description of the Affected Environment and Impact Analysis 4-299

expected to contact beach mice or their habitats. Onshore facilities are unlikely to be located in 

close proximity to beach mouse habitat. A review of the available information shows that reasonably 

foreseeable impacts on beach mice from accidental impacts associated with OCS oil- and gasrelated activities would be negligible. 

Cumulative activities have the potential to harm or reduce the numbers of the four listed 

subspecies of beach mouse. Those activities include oil spills, alteration and loss of habitat, 

predation and competition, ingestion and entanglement in beach trash and debris, and natural 

catastrophes (hurricanes and tropical storms). Most spills that may occur as a result of the proposed 

activities are not expected to contact beach mice or their habitats because they use areas above the 

intertidal zone where contact is less likely. Within the last 30-40 years, the combination of habitat 

loss due to beachfront development, the isolation of remaining beach mouse habitat areas and 

populations, and the destruction of remaining habitat by tropical storms and hurricanes have 

increased the threat of extinction of several subspecies of beach mice. Given these other 

cumulative factors and their relative impacts on the beach mouse and their habitat, the expected 

incremental contribution of OCS oil- and gas-related activities from a proposed lease sale under 

Alternative A to the cumulative impacts is negligible. 

4.9.3.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of this alternative would be the same as those identified in Alternative A, as 

portions of the proposed lease sale area under both alternatives (i.e., the CPA/EPA) are near beach 

mouse habitat. Reasonably foreseeable impacts are expected to be negligible for the reasons 

provided under Alternative A. The beach mouse subspecies included in the analysis are distributed 

across coastal Alabama and the Florida panhandle, and are adjacent to the EPA and CPA. Impacts 

from activity in the WPA are not expected due to the distance from beach mouse habitat. The WPA 

is approximately 380 mi (612 km) from known beach mouse habitat; OSRA reports calculated a 

<0.05 to 1 percent chance of oil contacting beach mouse habitat 30 days post-spill.

4.9.3.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

The impacts of Alternative C would yield negligible impacts to beach mice as a result of any 

new leases in the WPA and related Gulfwide postlease activities since the subspecies distributions 

are limited to coastal Alabama and the Florida panhandle as described in Alternative A.

4.9.3.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

The impacts of this alternative would be the same as those identified in either Alternative A, 

B, or C because the Topographic Features, Live Bottom (Pinnacle Trend), and Blocks South of 

Baldwin County, Alabama, Stipulations do not directly affect the beach mouse or its habitat and 
4-300 Gulf of Mexico Multisale EIS

because of the small number of blocks subject to these stipulations and their distance from beach 

mice habitat. Reasonably foreseeable impacts would be negligible.

4.9.3.2.5 Alternative E—No Action

If a proposed lease sale does not occur, then there would be no additional impacts to beach 

mice as there would be no lease sale held, thus leading to no new impacts from OCS oil- and gasrelated activities resulting from a lease sale. There would be no incremental contribution to 

cumulative impacts on the species or habitat; however, other past lease sales, postlease activities 

related to those other lease sales, or other authorized OCS oil- and gas-related activities may 

continue and have an incremental increase on the impacts on these subspecies of beach mouse.

4.9.4 Protected Birds

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

with a GOM proposed action and a proposed action’s incremental contribution to the cumulative 

impacts to ESA-listed birds are presented in this chapter. The approach of the analysis is to focus 

on the potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., 

exploration, development, and production), as well as accidental events and cumulative impacts, 

and to define impact-level measures for each impact-producing factor (refer to Table 4-13 in 

Chapter 4.9).

4.9.4.1 Description of the Affected Environment

The protected birds analyzed in this Multisale EIS include those species that use the OCS or 

coastal counties/parishes along the Gulf of Mexico during any part of their lifecycle and are listed 

under the Endangered Species Act as threatened or endangered. Other species that met these 

criteria were excluded if their habitats were more upland or away from the coast (Appendix F). All 

of the following protected bird species are also protected under the Migratory Bird Treaty Act. The 

impact-producing factors that could affect protected birds are outlined in Table 4-13 in Chapter 4.9. 

A review of a description of associated impact-producing factors for these species is discussed in 

detail and can be referenced from Chapter 4.8 (Birds). However, similar impact-producing factors 

that may affect protected species may have greater impacts to protected species populations due to 

their smaller population size. Those impacts are considered in the following analysis.

The habitats of the protected bird species described in this Multisale EIS vary from upland 

habitat, freshwater wetlands, estuarine, coastal beaches, and tidal flats to offshore migration and 

foraging; impacts to the physical aspects of the coastal habitats are identified in Chapter 4.3

(Coastal Habitats). Critical habitat is presented in Figure 4-23.

Collectively, the bird species included in this analysis are distributed across the GOM region 

from southern Florida to eastern Texas as year-round residents or migratory with a strong seasonal 

component. Many of the migratory bird species are less abundant along the GOM during the 
Description of the Affected Environment and Impact Analysis 4-301

season when they are on their breeding grounds and have higher densities and/or wider distributions 

during migration and non-breeding season.

Cape Sable Seaside Sparrow

The Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis) was originally 

federally listed as endangered on March 11, 1967. A South Florida Multi-Species Recovery Plan 

was completed on May 18, 1999. A Five-Year Status Review was completed on August 18, 2010, 

indicating continued declines; therefore, there was no change to its status. The average estimated 

population size for all six subpopulations from 2005 to 2009 was 3,021 individuals (USDOI, FWS 

2010b). A final rule for critical habitat designations was issued in 2007 (Federal Register, 2007).

It is a resident species associated with marl prairie and ephemeral wetlands, and is 

distributed in six small isolated populations in southern Florida, including Collier, Miami-Dade, and 

Monroe Counties along the Gulf Coast. These populations are located in areas where OCS oil- and 

gas-related activities would rarely occur. Habitat loss and fragmentation through wetland drainage, 

tilling, diking, controlled burns, agriculture activities, and commercial and private development in its 

preferred habitat are likely the primary causes for its original listing. The species appears to have 

highly variable nest success and survival (Boulton et al., 2009), which is problematic for a species 

with such low population numbers. Overall, this population appears to be limited by available 

nesting habitat and the “normal” onset of summer rains that result in decreased productivity later in 

the nesting season (Nott et al., 1998; Elderd and Nott, 2008) rather than restricted dispersal due to 

fragmented habitat (Van Houtan et al., 2010).

Piping Plover

Two populations of piping plover (Charadrius melodus) winter along the Gulf Coast and are 

recognized under the ESA: the Great Lakes (endangered) and the Great Plains (threatened) 

populations (Federal Register, 1985). The Great Plains population breeds primarily along the 

Missouri River system and its tributaries, as well as alkali wetlands and lakes in the Dakotas, 

Montana, and in prairie Canada; this population winters primarily along the GOM (Haig et al., 2005; 

Roche et al., 2010). The Great Lakes population breeds primarily along the shores and cobble 

beaches and associated islands with similar substrate in the Great Lake States and Canadian 

provinces (Stucker et al., 2010); the population winters primarily along the south Atlantic Coast with 

the greatest densities between St. Catherine’s Island, Georgia, and Jacksonville, Florida, but it can 

be found as far west as the Laguna Madre, Texas (Stucker and Cuthbert, 2006; Gratto-Trevor et al., 

2009). As much as 75 percent of all breeding piping plovers may winter along the GOM, spending 

up to 8 months on the wintering grounds (February-October).

The latest Five-Year Review was published on September 29, 2009, with recommendations 

that their status remain unchanged. Habitat loss and degradation due to commercial, residential, 

and recreational developments on both breeding and wintering areas is the likely cause for declines. 

The piping plover is considered a State Species of Conservation Concern in all Gulf Coast States. 
4-302 Gulf of Mexico Multisale EIS

The piping plover population estimates indicate declines for at least two of three populations at their 

breeding grounds (Great Lakes and Atlantic) (Haig et al., 2005; Roche et al., 2010).

In order to protect migratory birds, it is important to consider all seasonal habitats in the area 

of potential impacts that are used during the life cycle of the species. The habitats used by wintering 

birds along the GOM include beaches, mud flats, sand flats, algal flats, and washover passes (areas 

where breaks in the sand dunes result in an inlet). Wintering plovers are dependent on a mosaic of 

habitat patches and move among these patches depending on local weather and tidal conditions. It 

has been hypothesized that, because of habitat attributes (i.e.., foraging and roosting opportunities), 

specific wintering habitat may attract the largest concentrations of piping plovers because of a 

preferred prey base and/or because the substrate color provides protection from aerial predators 

due to cryptic blending camouflage color (Nicholls and Baldassarre, 1990).

Rufa Red Knot

The rufa red knot (Calidris canutus rufa) subspecies is a small, migratory shorebird that was 

recently listed as threatened in January 2015 (Federal Register, 2014d). There is currently no 

established critical habitat or recovery plan for rufa Red Knot.

Three of the six subspecies of red knot occur in North America, all three of which breed in 

the Arctic; the rufa subspecies occurs along the coast of the Gulf of Mexico. The rufa Red Knot is a 

long distance migrant that traverses the North and South America continents via the Atlantic Coast 

or a mid-continental route, roughly 9,300 mi (15,000 km). During spring and fall migration, it uses 

coastal beaches, bays, tidal flats, salt marshes, and lagoons primarily along the Atlantic and Gulf 

Coasts, which may serve as the final wintering destination for some birds.

Habitats used by red knots in migration and wintering are similar in character. For wintering, 

they generally use coastal marine and estuarine habitats with large areas of exposed intertidal 

sediments. In North America, red knots are commonly found along sandy, gravel, or cobble 

beaches, tidal mudflats, salt marshes, shallow coastal impoundments and lagoons, and peat banks. 

The supra-tidal (above the high tide) sandy habitats of inlets provide important areas for roosting, 

especially at higher tides when intertidal habitats are inundated. In wintering and migration habitats, 

red knots commonly forage on bivalves, gastropods, and crustaceans.

Within the GOM region, wintering birds are found primarily in Florida and Texas, but the 

species has also been observed in Louisiana, Alabama, and Florida. The red knot uses salt marsh, 

brackish lagoons, tidal mudflats, mangrove areas, and beach habitats. In Lee County, on Florida’s 

Gulf Coast, during fall migration, the red knot used intertidal substrates on ocean beaches at inlets. 

Along the Texas coast, red knots forage on beaches, oyster reefs, and exposed bay bottoms, and 

they roost on high sandflats, reefs, and other sites protected from high tides.

Based on the best available information, there is currently no precise population estimate for 

this subspecies; however, since 2000, declines of 70-75 percent have been recorded in Tierra del 
Description of the Affected Environment and Impact Analysis 4-303

Fuego for the wintering birds and in Delaware Bay during the spring migration. Harvesting of 

horseshoe crabs in Delaware Bay has reduced their availability as a major food source near 

Delaware Bay, resulting in negative effects to the population. This is an important source of nutrition 

for the migrating birds that stop to refuel during their transition between wintering and breeding 

grounds. Declines have also been observed in the population that departs the central Canadian 

Arctic in August.

Roseate Tern

The North American subspecies of roseate tern (Sterna dougallii dougallii) is separated into 

two distinct population segments according to the location of the breeding areas: the Northeastern 

population (along the Atlantic Coast from Nova Scotia to North Carolina and Bermuda) fluctuating 

around 3,500 breeding pairs, which is listed as endangered; and the Southeast U.S./Caribbean 

population (including Florida, Puerto Rico, and the Virgin Islands) with between 4,000 and 5,000 

breeding pairs, which is listed as threatened (Gochfeld et al., 1998). Both populations were listed on 

November 11, 1987, due to habitat loss as well as increased competition and predation (Federal 

Register; 1987). Recovery plans for the Northeast and Caribbean populations were completed on 

September 24, 1993, and November 5, 1998, respectively.

The Northeastern population breeds in the northeastern United States and eastern Canada 

(Kirkham and Nettleship, 1987) with migratory routes over the open ocean to the West Indies and 

South America. Migratory information for the Caribbean population is less understood, but 

information for the Florida breeders indicates peak arrival in mid-April to mid-May and peak 

departure in mid-August to mid-September. By the 1990’s, there were two remaining nesting sites in 

Florida: Pelican Shoal and the rooftop of the Marathon Government Building in Monroe County, 

Florida (Zambrano et al., 2000). These sites are in the Florida Keys and far from potential 

interactions from proposed OCS oil- and gas-related activities. In Florida, approximately 

350 breeding pairs are estimated, with 15-225 pairs in the Dry Tortugas (USDOI, FWS, 2010c). 

Terns are seabirds that forage by plunge diving for small fish in coastal and pelagic waters. The 

roseate tern is considered a State Species of Conservation Concern in Florida and is protected by 

the Migratory Bird Treaty Act.

Mississippi Sandhill Crane

The population of Mississippi sandhill crane (Grus canadensis pulla) has a nonmigratory, 

resident population with an extremely limited distribution (Jackson County, Mississippi). This 

subspecies was listed as endangered on June 4, 1973 (Federal Register, 1973b), due to a small 

population size, restricted distribution, habitat loss, and habitat fragmentation (consisting of wet pine 

savanna). This species is presently reproductively isolated and persists primarily due to 

augmentation from a captive-breeding program. In February 2015, there were 126 cranes in the wild 

population; annual reports are provided for updates on the FWS’s website (USDOI, FWS, 2015). At 

present, much of its habitat is protected in the Mississippi Sandhill Crane National Wildlife Refuge. 

Three separate critical habitat designations were completed in the 1970’s (Federal Register, 1975, 

1977a, and 1977b). The I-10 corridor jeopardized the existence of this population, but a settlement 
4-304 Gulf of Mexico Multisale EIS

agreement resulted in the Mississippi Department of Transportation purchasing 1,960 ac (793 ha) to 

be set aside as habitat, and an interchange was built (USDOI, FWS, 1991). The Mississippi Sandhill 

Crane National Wildlife Refuge in Jackson County, Mississippi, represents 74 percent of the total 

acres of critical habitat (USDOI, FWS, 1991). 

The sandhill crane feeds primarily on land or in shallow emergent wetlands. In fall and 

winter, Mississippi sandhill cranes roost mainly in the Pascagoula Marsh (Tacha et al., 1992), thus 

making them vulnerable to coastal or offshore oil spills if a spill reached their roosting habitat within 

estuarine marshes.

Whooping Crane

The Whooping Crane (Grus americana) was federally listed as endangered on March 11, 

1967, primarily due to overhunting and habitat loss (Federal Register, 1976). In 1941, only 

15 whooping cranes remained. Critical habitat (established in 1978) along the Gulf Coast is within 

the Aransas National Wildlife Refuge in Texas (Federal Register, 1978).

The Whooping Crane currently exists in the wild as one self-sustaining wild population (i.e., 

the Aransas-Wood Buffalo National Park Population) and the released, experimental, nonessential 

populations including Florida, Louisiana, Wisconsin, Colorado, Idaho, Wyoming, New Mexico, and 

Utah (Federal Register, 2011c). There are 12 captive sites that contribute to the captive breeding 

and release program (USDOI, FWS, 2012). The self-sustaining Aransas-Wood Buffalo population 

spans across Kansas, Montana, Nebraska, North Dakota, Oklahoma, South Dakota, and Texas 

during migration. As of February 2015, the three wild populations were estimated at 442 individuals 

(USDOI, FWS, 2015). This includes the only self-sustaining population, i.e., the Aransas-Wood 

Buffalo population, which is estimated at 308 birds from the FWS 2014-2015 annual survey of their 

wintering grounds in Texas (USDOI, FWS, 2015). This population nests in Wood Buffalo National 

Park and adjacent areas in Canada, and it winters in coastal marshes in Texas. The majority of the 

Aransas-Wood Buffalo National Park population migrates down through the Dakotas, Nebraska, 

Kansas, and Oklahoma before arriving on the wintering grounds in the coastal marshes and 

estuarine habitats in the Aransas National Wildlife Refuge in Texas where they typically arrive by 

late October to mid-November and depart in late March to mid-April. As of February 2015, there 

were 603 whooping cranes in the total North America wild and captive populations.

Whooping cranes have a strong tendency to show site fidelity to previously used locations for 

breeding, migrating, and roosting sites. Preferred roosting habitat includes open areas with sand 

and gravel bars or shallow water in rivers and lakes (Federal Register, 1978). Coastal Texas has a 

low probability of impact from proposed OCS oil- and gas-related activities.

Wood Stork

The wood stork (Mycteria americana) is the largest breeding wading bird and the only stork 

native to the U.S. The U.S. breeding population of the wood stork was listed as endangered on 

February 28, 1984 (Federal Register, 1984). The species was formally downlisted to threatened on 
Description of the Affected Environment and Impact Analysis 4-305

July 30, 2014, as a result of a population increase and expansion of the breeding range (Federal 

Register, 2014e). It was originally listed as a result of three potentially interacting factors: loss of 

preferred wetland habitats and associated available nesting sites; lack of protection at nest sites; 

and loss of preferred foraging habitats and/or prey (Brooks and Dean, 2008). The wood stork 

population in the southeastern U.S. appears to be stable or increasing (Borkhataria et al., 2008; 

Brooks and Dean, 2008). The wood stork is considered a State species of Conservation Concern in 

all Gulf Coast States except Louisiana. No critical habitat rules have been published for this 

species. 

Its distribution is restricted to freshwater and estuarine wetlands in the southeastern U.S., 

including North and South Carolina, Georgia, Florida, Alabama, Mississippi, and Louisiana, although 

it is no longer considered to breed in the latter three states (Coulter et al., 1999). For more 

information regarding coastal habitats and proposed OCS oil- and gas-related activities, refer to 

Chapter 4.3 (Coastal Habitats). Breeding locations often change annually due to variation in 

wetland conditions and because of the ability of breeding pairs to track resource availability (i.e., 

wetland conditions and food); not all colonies are occupied every year (Kushlan and Frohring, 1986; 

Bryan et al., 2008). Birds located at the northern edge of the breeding range tend to migrate south 

to winter in southern Georgia and Florida (USDOI, FWS, 2007). Though storks breed throughout 

Florida, it appears the center of the traditional breeding range has shifted northward primarily into 

north and central Florida, Georgia, and South Carolina (Kushlan and Frohring, 1986; Ogden et al., 

1987; Rodgers et al., 2008). There is evidence of relatively major post-breeding dispersal with large 

numbers of birds frequently observed in the Mississippi River Valley; some mixing of U.S. and 

Mexican populations may occur (Bryan et al., 2008).

4.9.4.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from activities described in Chapter 3

and their potential effects that would potentially result from a single lease sale or the alternatives. 

This analysis applies to all considered alternatives. Because of the distribution of the different 

protected bird species in the Area of Interest, the level of impacts would vary from Alternatives A, B, 

C, and D. However, Alternative E, No Action, would only have impacts associated with continuing 

effects from past lease sales and non-OCS oil- and gas-related activities. This chapter will include a 

summary of the potential impacts as they relate to the action alternatives and the protected bird 

species. The analyses of applicable impact-producing factors are the same as those for birds in 

general (refer to Chapter 4.8.2, Birds); however, the resulting level of impact would differ, as defined 

under the protected species impact criteria.

Routine Activities

The major impact-producing factors associated with routine activities include those that may 

affect birds found in coastal areas, including beaches, wetlands and mudflats, or offshore. For more 

details on impacts to birds in general, refer to Chapter 4.8.2 (Birds). Also, since many of these birds 

are found in coastal areas, refer to Chapter 4.3.2 (Coastal Habitats) for information on impacts from 
4-306 Gulf of Mexico Multisale EIS

the proposed activities on coastal habitats. The Red Knot, Piping Plover, and Roseate Tern are the 

only protected bird species that may be found offshore during migration or foraging. The Mississippi 

Sandhill Crane, Whooping Crane, and Wood Stork use wetland areas that are associated with 

coastal marshes. The Cape Sable Seaside Sparrow and Roseate Tern are only in extreme south 

Florida. The Piping Plover and rufa Red Knot use beach and mudflat areas across the Gulf of 

Mexico at suitable wintering and stop-over locations.

Routine impacts include discharges and wastes, air and water quality (Chapters 4.1 and 

4.2), structure presence, lighting, noise, and marine debris. Waste discharges to air or water 

produced as a result of routine activities are regulated by the USEPA and BOEM and result in 

reduced potential impacts. Due to precautionary requirements and monitoring, and that most of the 

protected birds are in coastal areas away from many of the discharge and waste associated with a 

proposed action, the impacts to protected birds would be negligible. 

Structure presence and lighting could impact bird species by collision and behavioral 

changes that may lead to mortality. In the Gulf of Mexico, Russell reported that many species of 

songbirds, shorebirds, wading birds, and raptors were involved in collisions or circulating events 

(Russell, 2005). The Red Knot, Piping Plover, and Roseate Tern would be the only protected bird 

species to use the offshore environment since the Piping Plover and Red Knot migrate across the 

Gulf and the Roseate Tern forages offshore; however, only the knot was detected during Russell’s 

study. The impacts of offshore structures to protected birds would be negligible to moderate since 

most of the protected bird activity is associated with coastal habitats and is not near the offshore 

structures. Moderate impacts would occur if a protected bird species changes its normal migratory 

behavior due to artificial lighting or if there is a collision with a platform.

Operational noise from OCS oil- and gas-related helicopters and vessel traffic (including 

G&G activities) may cause temporary disturbance to any bird that is near the flight path or landing 

areas. Due to the short-term nature of the impact and that many of these birds would not be in the 

area of known flight paths, the impact would be negligible. 

Marine debris produced by OCS oil- and gas-related activities as a result of accidental 

disposal into the water may affect protected birds by entanglement or ingestion. Due to the 

regulations prohibiting intentional disposal of items, impacts would be negligible to moderate. 

Impacts would be negligible through beach-cleaning efforts to remove debris from certain locations 

and the use of marine debris awareness and prevention measures on the oil and gas industry 

through NTL 2015-BSEE-G03 (formerly NTL 2012-BSEE-G01), which provides guidance to industry 

operators regarding the reduction of trash and debris elimination into the marine environment and 

which informs operators of regulations set by other regulatory agencies (i.e., the USEPA and 

USCG). Implementation of BSEE’s Marine Trash and Debris NTL is required through ESA 

consultation with the FWS and is expected to be applied by the oil and gas industry for associated 

OCS oil- and gas-related activity. Moderate impacts would occur if one of the protected bird species 

has a negative interaction with trash or debris, leading to mortality.
Description of the Affected Environment and Impact Analysis 4-307

Accidental Events

The major impact-producing factors resulting from accidental events associated with 

proposed OCS oil- and gas-related activities that may affect protected birds include accidental oil 

spills and response efforts. All species of protected birds in the potentially affected area could be 

impacted by an accidental oil spill and response activities. In the case of an accidental oil spill, 

impacts would be negligible to moderate depending on the magnitude of the oil spilled and 

spatiotemporal proximity of such an event to the particular species of protected birds. These impact 

levels would also be related to the possible response activities. The impacts would depend on the 

seasonal timing related to migration or breeding seasons where birds may be absent or present in 

higher densities. Impacts from oil spill on birds are discussed in Chapter 4.8.2 (Birds), but oil spills 

may have a greater impact on protected species due to their ESA listing criteria.

During the Deepwater Horizon explosion, oil spill, and response, there were at least 

100 species of birds directly affected by oil or associated with oil-affected habitats. Due to the timing 

and location of the spill, Piping Plovers were the only ESA-listed species that incurred mortality and 

loss of productivity (Deepwater Horizon Natural Resource Damage Assessment Team, 2016).

Cumulative Impacts

The cumulative impacts of the OCS oil and gas program that could affect protected birds are 

impacts to air and water quality, noise, G&G activities, platform presence and lighting, and 

construction. Mortality associated with collision with offshore structures has been reported in the 

Gulf of Mexico (Russell, 2005). Behavioral changes have also been observed with lighting 

associated with offshore structures. Migratory birds may become disoriented with the lights, 

expending energy in excessive circular flight. This can lead to exhaustion and mortality for 

individuals that are already metabolically compromised due to the energy expense of migratory 

flight. Accidental events include oil spills and related cleanup, impacts of which are discussed in 

detail in Chapter 4.8.2 (Birds).

As for non-OCS oil- and gas-related events, State oil- and gas-related activities would have 

the same general impact-producing factors as the OCS oil- and gas-related activities discussed 

above; however, the activities would be in closer proximity to protected bird species’ coastal habitat. 

The Mississippi River watershed contributes nutrients, causing a seasonal population explosion of 

phytoplankton, which creates a hypoxic or anoxic area. This can decrease fauna in the upper water 

column and decrease chances of successful forging for birds, leading to changes in behavior and 

decreased health condition; therefore, impacts are expected to be negligible to moderate. Wetland 

and beach loss would continue in the foreseeable future and would have a major impact to protected 

birds. Most of the coastal habitats used by protected birds are regulated and mitigated by different 

Federal and State agencies; however, continued coastal erosion and wetland loss is expected along 

the Gulf of Mexico. As noted earlier, piping plover population estimates indicate declines for at least 

two of three populations at their breeding grounds (Haig et al., 2005; Roche et al., 2010). Emerging 

infectious diseases such as the West Nile virus, Avian influenza, and Newcastle disease may impact 

protected birds, and impacts would be expected to be major if protected species populations were 
4-308 Gulf of Mexico Multisale EIS

affected by such pathogens. Non-OCS impacts overall are expected to be negligible to major

depending on the degree of impact

When considering the cumulative impacts to the protected bird species, the incremental 

contribution to impacts would be negligible from a proposed action. A proposed action would yield 

a much smaller impact proportionately when compared with the impacts from multiple sources as 

noted above.

4.9.4.2.1 Alternative A—Regionwide OCS Proposed Lease Sale (The Preferred Alternative)

The impact-producing factors associated with the Alternative A would include all those listed 

above. The mitigations would be the same for protected birds across the GOM. The impacts from a 

proposed action are expected to be negligible to moderate because of current and ongoing 

mitigations that are in place and applied during postlease activity reviews. Moderate impacts are not 

expected but may occur if a protected bird species suffers mortality as a result of encountering 

marine debris or an accidental oil spill and cleanup activities.

4.9.4.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of Alternative B would be the same as Alternative A for all previously specified 

protected bird species, with the exception of the whooping crane with the listed population in Texas 

and outside of the CPA or EPA. Wintering Whooping Crane critical habitat is near Port Aransas, 

Texas, along a coastal area of the WPA. The expected impacts to the whooping crane would be 

negligible, but the impacts may be moderate in the unlikely event (which is seasonally dependent 

according to the timing of the incident and the presence of the species at the time) of an oil spill in 

the CPA/EPA, resulting in the death of at least one bird.

4.9.4.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

The impacts of this alternative would be the same as Alternative A for the species that occur 

in the WPA. The Cape Sable seaside sparrow, roseate tern, and the Mississippi sandhill crane are 

not found off Texas; therefore, they would not be impacted by a proposed lease sale in the WPA. 

Existing lease activity in the CPA and EPA and new activity in the WPA could yield negligible to 

moderate impacts. Moderate impacts may occur if a protected bird species is affected by an 

accidental oil spill and/or response. 

4.9.4.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

The impacts of this alternative would be the same as Alternative A, B, or C because these 

stipulations are specific to areas that do not have any impact on ESA-protected bird species or their 

habitats.
Description of the Affected Environment and Impact Analysis 4-309

4.9.4.2.5 Alternative E—No Action

The impacts of Alternative E would yield no additional impacts to protected birds. There 

would be no additional incremental contribution to the cumulative impacts to ESA-protected bird 

species or their habitats.

4.9.5 Protected Corals

This chapter provides detailed information regarding the protected coral species. However, 

the impact-producing factors and impact levels on these species are the same as those described in 

Chapter 4.6.1 (Topographic Features) and the respective Table 4-8; therefore, they are summarized 

here. A full impact analysis for corals may be found in Chapters 4.6 (Live Bottom Habitats).

4.9.5.1 Description of the Affected Environment

Corals in the GOM that are protected under the ESA include those listed in Table 4-13. 

Distribution of the listed species within the jurisdiction of the United States ranges from the State of 

Florida, Flower Garden Banks National Marine Sanctuary, and the U.S. territories of Puerto Rico, 

U.S. Virgin Islands, and Navassa Island. Critical habitat was designated for the elkhorn (Acropora 

palmata) and staghorn (Acropora cervicornis) coral species by the NMFS in 2008 and includes four 

counties in the State of Florida (Palm Beach, Broward, Miami-Dade, and Monroe Counties), as well 

as the U.S. territories of the U.S. Virgin Islands (St. John/St. Thomas and St. Croix) and Puerto Rico 

(Federal Register, 2008d). However, this designated critical habitat is located outside of the GOM 

and is not expected to be affected by a proposed action, as seen in Figure 4-23 in Chapter 4.9. 

Though the listed species are protected, they would have the same potential impacts from a 

proposed action as other coral species. For a detailed description and impact analysis of corals in 

the GOM, refer to Chapter 4.6. 

Elkhorn coral and staghorn coral were listed as threatened under the ESA in 2006 (Federal 

Register, 2006c). Both corals naturally occur on spur and groove, bank reef, patch reef, and 

transitional reef habitats, as well as on limestone ridges, terraces, and hard bottom habitats 

(Goldberg, 1973; Gilmore and Hall, 1976; Cairns, 1982; Davis, 1982; Jaap, 1984; Wheaton and 

Jaap, 1988; Miller et al., 2008). During the 1970’s and 1980’s, both elkhorn and staghorn corals 

underwent swift declines in abundance throughout their ranges. Although data suggest that whiteband disease, a disease that affects acroporid corals and is distinguishable by the white band of 

dead coral tissue that it forms, was the primary cause of initial decline in Atlantic/Caribbean elkhorn 

and staghorn coral abundances, other threats, such as elevated seawater temperatures, ocean 

acidification, and physical damage from hurricanes, are credible and potentially significant

impediments to recovery of these species (USDOC, NMFS, 2015i). Additionally, anthropogenic 

physical damage (e.g., vessel groundings, anchors, divers, and snorkelers), coastal development, 

competition, and predation were deemed by the NMFS to be moderate threats to both corals in the 

recent recovery plan (USDOC, NMFS, 2015i).
4-310 Gulf of Mexico Multisale EIS

On September 10, 2014, the Federal Register published a final rule listing the boulder star 

coral (Orbicella franksi), lobed star coral (Orbicella annularis), and mountainous star coral (Orbicella 

faveolata) as threatened under the ESA (Federal Register, 2014b). This Orbicella species complex 

occurs in the western Atlantic and greater Caribbean, including the Flower Garden Banks. It has 

historically been a dominant component on Caribbean coral reefs, characterizing the so-called 

“buttress zone” and “annularis zone” in the classical descriptions of Caribbean reefs. The species 

complex has also become the major reef-builder in the greater Caribbean since the die-off of 

Acropora spp. (USDOC, NMFS, 2015i).

The species complex has high susceptibility to negative impacts from ocean warming, 

acidification, disease, sedimentation, and nutrients; some susceptibility to trophic effects of fishing 

and sea-level rise; and low susceptibility to predation (USDOC, NMFS, 2015i).

Between 1999 and 2009, overall cover of the Orbicella species complex in the Florida Keys 

declined, but it differed by habitat type (Ruzicka et al., 2013). Percent cover declined on the deep 

and shallow fore-reefs but remained stable on patch reefs (Ruzicka et al., 2013). In 2010, a coldwater bleaching event occurred in the Florida Keys where water temperatures dropped into the 

upper 40’s and lower 50’s, which is about 20 oF (-7 oC) lower than the typical temperatures in the 

upper 60’s (USDOC, NMFS, 2015i). This event reduced cover of the Orbicella species complex 

from 4.4 percent to 0.6 percent on four patch reefs in the upper and middle Florida Keys. However, 

random surveys between 2002 and 2006 in the Flower Garden Banks found that the Orbicella

species complex (predominantly O. franksi) was the dominant coral, comprising between 27 and 

40 percent benthic cover (Hickerson et al., 2008).

4.9.5.2 Environmental Consequences

The impact-producing factors and impact levels on these species are generally the same as 

those described in Chapter 4.6.1 and Table 4-8 and, therefore, are summarized here. The activities 

as a result of a proposed lease sale could directly impact protected coral habitat within the GOM. 

Because of the similarity and overlap of the effects of many activities that occur in the OCS, all 

possible impact-producing factors result from bottom-disturbing activities and the potential release of 

drilling muds and contaminants.

Routine Activities

Potential routine impact-producing factors on protected corals are the same as those 

analyzed and described in Chapter 4.6.1. Impacts resulting from all of the routine activities are 

mitigated through the Topographic Features Stipulation, and the protective measures are 

summarized and detailed in NTL 2009-G39. The site-specific survey information and distancing 

requirements described in NTL 2009-G39 would allow BOEM to identify and protect live bottom 

features (which protected corals may inhabit) from harm by proposed OCS oil- and gas-related 

activities during postlease reviews. Further, many of the protected corals either occur in the Flower 

Garden Banks National Marine Sanctuary, which is currently excluded from future leasing, or are far 

from the area of proposed activities. Assuming adherence to all expected lease stipulations and 
Description of the Affected Environment and Impact Analysis 4-311

other postlease, protective restrictions and mitigations, along with site-specific reviews of proposed 

activities, the routine activities related to a proposed action are expected to have negligible impacts. 

Accidental Events

While accidental events have the potential to cause severe damage to specific coral 

communities, the number of such events is expected to be small. Impacts resulting from bottomdisturbing activities, as described under “Routine Activities” in Chapter 4.6.1, are largely the same 

for accidental events. If the spill occurs close to a protected coral community, those communities 

may become smothered by the particles and exposed to hydrocarbons, which have the potential to 

severely impact protected corals via mortality, loss of habitat, change in community structure, and 

failed reproductive success. Beyond the area of spilled oil, impacts are expected to be less severe 

as particles are biodegraded and become more widely dispersed. Many of the protected corals 

either occur in the Flower Garden Banks National Marine Sanctuary, which is currently excluded 

from future leasing, or are far from the area of proposed activities. Therefore, impacts from 

reasonably foreseeable accidental events are expected to be negligible to minor, short in duration, 

and limited to the area where the accident occurs. A negligible impact would be largely 

undetectable and may cause slight, localized changes to a protected coral species community where 

recovery from the impact is expected. A minor impact would be detectable and could result in 

noticeable changes to a protected coral species community, but impacts would be spatially localized, 

short term in duration, and recovery from the impact would be expected.

Cumulative Impacts

Proposed OCS oil- and gas-related activities would contribute incrementally to the overall 

OCS and non-OCS cumulative impacts experienced by corals. A variety of non-OCS oil- and gasrelated activities, including fishing and anchoring, along with shifting natural conditions such as 

invasive species and climate change, may have a considerable impact on these habitats in the 

future. These alternatives would also do little to increase the cumulative impacts since many blocks 

near the features are already leased and non-OCS oil- and gas-related activities are not expected to 

decrease. BOEM recognizes these impacts and has determined that a proposed action would not 

increase the cumulative effects on protected corals beyond what they are currently experiencing. 

Overall, impacts of non-OCS oil- and gas-related activities are expected to range between 

negligible to moderate depending on the amount of activity in the vicinity of the protected coral 

community. For example, climate change may have a moderate impact to a protected coral 

community, causing changes in community structure and ecological functioning. As such, the 

incremental contribution of OCS oil- and gas-related activities to the overall cumulative impacts of a 

proposed action, combined with non-OCS oil- and gas-related activities, is expected to be 

negligible. 

4.9.5.2.1 Alternatives A, B, and C

Under Alternatives A, B, and C, the proposed activities would have the same impact levels to 

coral habitats whether they occur in the WPA, CPA, or EPA. While the WPA is a smaller area with 
4-312 Gulf of Mexico Multisale EIS

less projected activity than is proposed for the CPA/EPA (refer to Chapter 3), many of the protected 

corals either occur in the Flower Garden Banks National Marine Sanctuary, which has no leasing, or 

are far from the area of proposed activities. Additional protection is provided through current and 

ongoing mitigations that are restated during postlease activity reviews. Because protected corals 

occur far from the area of proposed activities and are further protected through current and ongoing 

mitigations, impacts from reasonably foreseeable routine activities and accidental events are both 

expected to be negligible to minor. A minor impact would be detectable and could result in 

noticeable changes to a protected coral species community, but impacts would be spatially localized, 

short term in duration, and recovery from the impact would be expected.

4.9.5.2.2 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, should the blocks subject to the Topographic Features and Live Bottom 

(Pinnacle Trend) Stipulations be excluded, protected corals would be further protected by distancing 

OCS oil- and gas-related activities farther from these habitats, thereby reducing the probability of 

potential impacts from routine activities or accidental events. Blocks subject to the Topographic 

Features Stipulation include any available unleased block in which a No Activity Zone or Shunting 

Zone may be applied. A total of 207 blocks within the CPA and 160 blocks in the WPA are affected 

by the Topographic Features Stipulation. The exclusion of any of the other blocks subject to the 

Blocks South of Baldwin County, Alabama, Stipulation is not expected to change the impacts to 

protected corals because of the small number of blocks and their distance from these corals. For 

additional information related to the specific blocks that would be excluded, refer to Appendix D. 

Because protected corals occur far from the area of proposed activities and are further protected 

through current and ongoing mitigations, impacts from reasonably foreseeable routine activities and 

accidental events are both expected to be negligible to minor. A minor impact would be 

detectable and could result in noticeable changes to a protected coral species community, but 

impacts would be spatially localized, short term in duration, and recovery from the impact would be 

expected. However, under Alternative D, it would be very unlikely that protected corals would 

encounter any impact-producing factor from OCS oil- and gas-related activities if the blocks subject 

to the Topographic Features and/or the Live Bottom (Pinnacle Trend) Stipulations are excluded.

4.9.5.2.3 Alternative E—No Action

Under Alternative E, a proposed lease sale would not occur; therefore, no impacts to 

protected corals as a result of a proposed lease sale would occur. There would, however, be 

ongoing cumulative impacts to the resources associated with previous OCS oil- and gas-related 

activities and non-OCS oil- and gas-related activities. Development of oil and gas would, in all 

likelihood, be postponed to a future lease sale decision; in that case, the overall level of OCS oiland gas-related activity would be delayed, not reduced, at least in the short term. It would take 

several cancelled lease sales before there would likely be a noticeable decrease in postlease 

activities from previous oil and gas lease sales.
Description of the Affected Environment and Impact Analysis 4-313

4.10 COMMERCIAL FISHERIES

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

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

commercial fisheries are presented in this chapter. The approach of the analysis is to focus on the 

potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., exploration, 

development, and production), as well as accidental events and cumulative impacts, and to define 

the impact-level measures for each impact-producing factor (Table 4-15). The analysis in this 

chapter relies on the analysis and conclusions reached in Chapter 4.7 (Fish and Invertebrate 

Resources). This chapter describes the cause and effect analysis to the social endpoint for 

commercial fisheries. Therefore, in general, the impact-producing factors identified in Chapter 4.7

would have the potential to impact commercial fisheries as well.

Table 4-15. Commercial Fisheries Impact-Producing Factors.

Commercial Fisheries Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Fish Population Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Space-Use Conflicts Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Production Structure 

Emplacement and 

Removal

Beneficial to Beneficial to Beneficial to Beneficial to

None

Minor Minor Minor Minor

Accidental Impacts

Oil Spills Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Cumulative Impacts

OCS Oil and Gas

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible Minor Minor Minor Minor

Non-OCS Oil and 

Gas

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible Minor Minor Minor Minor

Impact-Level Definitions

In this chapter (and in the analyses of the alternatives), the impact measures are defined in 

terms of the intensity, duration, and geographical extent of the impacts to the human uses of 

commercial fisheries along the Gulf Coast. In particular, the impacts of each impact-producing factor 

are summarized in Table 4-15, using the impact-level measures below.
4-314 Gulf of Mexico Multisale EIS

• Beneficial – Impacts would be positive.

• Negligible – Little or no detectable impact.

• Minor – Impacts are detectable but less than severe.

• Moderate – Impacts are severe but are short term and/or not extensive.

• Major – Impacts are long term, extensive, and severe.

4.10.1 Description of the Affected Environment 

The Gulf of Mexico is home to a large and complex commercial fishing industry. There were 

$762.5 million in finfish and shellfish landings in the Gulf of Mexico in 2012, which comprised 

15 percent of total U.S. landings (USDOC, NMFS, 2014a). Some of the most economically 

important commercial fisheries in the Gulf of Mexico are white shrimp (Litopenaeus setiferus), brown 

shrimp (Farfantepenaeus aztecus), eastern oysters (Crassostrea virginica), Gulf menhaden 

(Brevoortia patronus), blue crab (Callinectes sapidus), red grouper (Epinephelus morio), red snapper 

(Lutjanus campechanus), and tunas (Thunnus spp.). Fisheries are managed by NOAA Fisheries 

(NMFS), as advised by the regional fisheries management councils. Commercial fisheries are 

regulated by various mechanisms, including permitting, closures, quotas, and gear restrictions; 

details regarding these mechanisms are described by the Gulf of Mexico Fishery Management 

Council (2015). This source also describes the allowable gear types for each fishery. Some of the 

most common gear types are trawls (for shrimp), purse seines (for menhaden), dredges (for 

oysters), traps (for blue crab), and longlines (for various finfish). The biological aspects of the 

affected environment for the targeted species are discussed in Chapter 4.7.1, the “Description of the 

Affected Environment” for Chapter 4.7 (Fish and Invertebrate Resources).

Landings Revenues

Panel A of Table 4-16 presents the total landings revenues for key GOM fisheries, while 

Panels B through F present the landings revenues for the key fisheries in each Gulf Coast State 

from 2009 through 2012. There were $762,514,000 in landings revenues in 2012, compared with 

$643,880,000 in 2009; $638,900,000 in 2010; and $818,505,000 in 2011. Fisheries offshore of 

Louisiana accounted for the most fisheries revenue in 2012, followed (in descending order) by 

Texas, West Florida, Mississippi, and Alabama. Shrimp species (particularly white shrimp and 

brown shrimp) account for the most landings revenues ($392,239,000 in 2012) in the Gulf of Mexico. 

Shrimp are caught offshore of all states, particularly Texas and Louisiana, in Federal and State 

waters. Menhaden landings accounted for the second most landings revenue ($87,376,000) in 

2012. Menhaden accounts for the most pounds (1.28 billion pounds in 2012) landed in the Gulf of 

Mexico (USDOC, NMFS, 2014a). However, the average price per pound of menhaden is much 

lower than for other species. Menhaden is primarily caught in State and Federal waters offshore of 

Louisiana and Mississippi. Oysters ($73,662,000) and blue crab ($52,879,000) accounted for the 

third and fourth highest landings revenues in 2012. These species are caught in State waters of all 

Gulf Coast States. Red snapper and tunas are primarily caught in Federal waters offshore various 
Description of the Affected Environment and Impact Analysis 4-315

states. Stone crab (Menippe mercenaria) and Caribbean spiny lobster (Panulirus argus) are 

primarily caught offshore Florida.

Table 4-16. Landings Revenues: Landings Revenue by Species and State.

Panel A: Regionwide Panel B: Louisiana

Species/Year 2009 2010 2011 2012 Species/Year 2009 2010 2011 2012

Shrimp 327,263 339,228 441,266 392,239 Shrimp 121,477 107,362 133,670 147,616

Menhaden 69,456 66,019 103,519 87,376 Menhaden 51,405 57,600 93,547 64,861

Oysters 73,473 55,088 65,098 73,662 Blue crab 37,306 30,325 36,784 43,097

Blue crab 45,476 41,264 48,605 52,879 Oysters 50,959 24,989 41,652 41,592

Stone crab 17,690 23,384 24,518 23,760 Crawfish 15,547 13,971 9,914 8,287

Groupers 17,291 13,580 18,988 23,427 Tunas 6,338 1,649 3,369 7,890

Red snapper 7,984 10,202 11,233 13,702 Red snapper 2,185 2,311 2,261 2,571

Tunas 8,180 2,688 5,298 10,655 King 

mackerel 1,184 1,149 1,594 1,475

Total 

Revenue 643,880 638,900 818,505 762,514 Total Revenue 296,778 247,831 334,789 331,165

Panel C: Texas Panel D: West Florida

Species/Year 2009 2010 2011 2012 Species/Year 2009 2010 2011 2012

Shrimp 135,643 173,556 216,382 159,534 Stone crab 17,586 23,335 24,427 23,750

Oysters 9,376 19,144 12,789 21,302 Shrimp 23,314 27,554 28,339 22,430

Red snapper 2,398 3,009 3,254 4,448 Lobsters 12,179 32,752 33,872 21,132

Blue crab 2,454 3,134 2,845 2,876 Red grouper 10,488 8,992 14,531 16,737

Black drum 1,377 1,573 1,448 1,486 Oyster 6,968 6,298 8,408 7,919

Vermilion 

snapper 1,233 1,337 1,274 1,434 Red snapper 2,980 4,552 5,237 6,141

Atlantic 

croaker 484 531 622 740 Blue crab 4,183 6,706 7,530 5,139

Groupers 641 356 549 723 Mullets 5,069 4,188 8,567 5,032

Total 

Revenue 155,074 203,795 240,566 194,044 Total Revenue 115,127 139,045 161,949 141,671

Panel E: Mississippi Panel F: Alabama

Species/Year 2009 2010 2011 2012 Species/Year 2009 2010 2011 2012

Shrimp 12,689 8,293 18,514 23,803 Shrimp 34,140 22,463 44,361 38,856

Menhaden 17,987 8,378 9,871 22,394 Oysters 77 390 1,322 1,253

Oysters 6,094 4,268 928 1,596 Mullets 765 594 687 1,204

Blue crab 573 366 318 724 Spanish 

mackerel 301 499 582 1,149

Red snapper 158 N/A 168 226 Blue crab 961 732 1,128 1,044

Total 

Revenue 38,033 21,895 30,291 49,295 Total Revenue 38,869 26,335 50,910 46,340

1

Landings are presented in thousands of dollars.

Source: USDOC, NMFS, 2014a.
4-316 Gulf of Mexico Multisale EIS

Fisheries Supply Chain

The fisheries landings discussed above are brought to shore at various ports along the Gulf 

Coast. Some of the leading commercial fishing ports, along with the fisheries revenues received in 

2012 at these ports, are Empire-Venice, Louisiana ($79.7 million); Galveston, Texas ($74.3 million); 

Dulac-Chauvin, Louisiana ($64 million); Brownsville-Port Isabel, Texas ($53.6 million); Port Arthur, 

Texas ($47.4 million); Intracoastal City, Louisiana ($43.9 million); and Bayou La Batre, Alabama 

($37.5 million) (USDOC, NMFS, 2015j). Fish landings then proceed through supply chains that 

include dealers, processors, distributors, markets, and restaurants. Economic modeling techniques 

were used to estimate the supply chain impacts of fisheries landings (USDOC, NMFS, 2014a). The 

NMFS’s estimates of the number of jobs and the amount of value-added supported by fisheries 

landings in each Gulf Coast State are listed below. The large impacts in Florida are due to its high 

numbers of seafood importers, wholesalers, distributors, and retailers.

• Texas (25,911 jobs; $ 1,036,657,000)

• Louisiana (33,391 jobs; $920,873,000) 

• Mississippi (8,532 jobs; $193,349,000) 

• Alabama (9,947 jobs; $229,316,000)

• Florida (82,141 jobs; $5,532,209,000)

4.10.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

commercial fisheries that would arise from projected activities from a proposed action are analyzed 

in this chapter. While there are some differences in the amount of activities associated with the 

alternatives, many of the impacts associated with the alternatives are similar. Therefore, this 

chapter will describe the impacts that are expected to apply to all alternatives, while any deviations 

from these impact conclusions will be discussed in Chapters 4.10.2.1-4.10.2.5. 

Routine Activities

Routine operations (such as seismic surveys [Chapter 3.1.2.1], drilling activities [Chapters 

3.1.2.2 and 3.1.3.1], service-vessel traffic [Chapter 3.1.4.4], and production structure emplacement 

[Chapter 3.1.3.3], and decommissioning [Chapter 3.1.6]) can impact commercial fisheries by 

impacting the fish populations that support commercial fishing or by impacting fishermen’s access to 

those fish populations. The impacts to fish populations that support commercial fishing are 

described in Chapter 4.7, which describes the impacts of anthropogenic sound, bottom-disturbing 

activities, and habitat modification on fish populations. The impacts to commercial fishing from 

routine activities would depend on the types and scales of commercial fishing activities in an 

impacted area, which are discussed in Chapter 4.10.1. Shrimp, menhaden, red snapper, tunas, and 

groupers are the fishes and invertebrates most often sought by commercial fishermen in Federal 

waters and would therefore be most directly impacted by a proposed action. Disturbances to those 
Description of the Affected Environment and Impact Analysis 4-317

populations would have proportionate impacts on the seafood supply chain. However, since the 

impacts to fish populations from routine OCS oil- and gas-related activities would be negligible or 

minor (determined in Chapter 4.7), the corresponding impacts to commercial fisheries would also 

be negligible or minor. This is because disruptions to fish populations would proportionately 

reduce commercial fishing revenues, as well as the impacts on the seafood supply chain.

Space-use conflicts with commercial fishing can arise from routine operations such as 

service-vessel traffic, seismic surveys, pipeline emplacement, drilling, and production structure 

emplacement and removals. The nature of space-use conflicts from these activities depend on the 

durations of the activities, as well as the locations and species affected. For example, structure 

emplacement prevents trawling in the associated area and, thus, could impact the shrimp fishery. 

However, the amount of area closed to trawling would be minimal relative to the vast areas where 

shrimp trawling occur (refer to Chapter 3.1.3.4.2). On the other hand, production platforms can 

facilitate fishing for reef fish such as red snapper and groupers. Scott-Denton et al. (2011) present 

observational data regarding the geographic distribution of various reef fish in the Gulf of Mexico, 

where structure production emplacement can enhance commercial fishing. The eventual 

decommissioning of a platform would reverse the effects of structure emplacement unless the 

structure were reefed in place or moved to an artificial reef site. Due to the small scale of a 

proposed action (Chapter 3), the impacts of space-use conflicts and structure emplacement and 

eventual decommissioning are expected to range from beneficial to minor. The exact impacts 

would depend on the locations of activities, the species affected, the intensity of commercial fishing 

activity in the affected area, and the substitutability of any lost fishing access.

Accidental Events

Accidental events, such as oil spills (Chapter 3.2.1), can impact commercial fisheries by 

impacting the fish populations that support commercial fishing activities, by impacting fishermen’s 

access to those fish populations, or by impacting the seafood supply chain. The impacts of oil spills 

on fish populations that support commercial fishing are described in Chapter 4.7, describes the 

impacts of potential sediment displacement due to a spill, as well as the potential lethal and 

sublethal impacts to fish and shellfish species. The corresponding impacts to commercial fishing 

would depend on the types and scales of commercial fishing activities in an impacted area, which 

are discussed in Chapter 4.10.1. Oil spills in Federal waters would be most likely to affect fisheries 

for coastal or oceanic species (such as shrimp, menhaden, reef fish, tunas, and groupers), and 

accidental spills in State waters would be most likely to affect coastal and inshore fisheries (e.g., 

shrimp, menhaden, oysters, and blue crab). Most commercially valuable species in the Gulf of 

Mexico have planktonic eggs and/or larvae. These early life stages are generally more vulnerable to 

impacts resulting from acute exposure to oil and could be affected if a spill coincides with a 

spawning event or impacts nursery habitat (e.g., Coastal Habitats [Chapter 4.3] or Sargassum and 

Associated Communities [Chapter 4.5]).

The area surrounding a spill could be closed to commercial fishing for some period of time. 

However, fishing closures would likely be limited in size and duration. Commercial fishermen would 
4-318 Gulf of Mexico Multisale EIS

likely have numerous alternate fishing sites for the duration of a closure. Oil spills can have other 

impacts to the supply or demand of seafood. Greater New Orleans, Inc. (2011) provides information 

regarding how the various impacts to commercial fisheries evolved subsequent to the Deepwater 

Horizon oil spill, which provides insights regarding the potential impacts of future spills. For 

example, an oil spill could cause seafood safety concerns, which would reduce the demand for the 

affected species. An oil spill could also cause certain fishermen to stop fishing to participate in the 

cleanup operations or for economic reasons. However, the oil spills that could arise from a 

proposed action are forecast to be small. Therefore, an oil spill would likely have limited impacts on 

fish populations, as well as limited impacts on the supply and demand for seafood. Therefore, the 

impacts of oil spills arising from a proposed action would be negligible to minor. The exact impacts 

would depend on the locations of oil spills, the species affected, the intensity of commercial fishing 

activity in the affected area, and the substitutability of any lost fishing access.

Cumulative Impacts

The cumulative impacts to commercial fisheries would be determined by the cumulative 

impacts to fish populations, which are discussed in Chapter 4.7. The impacts to fish populations 

would impact commercial fishing in proportion to the intensity of commercial fishing for a particular 

species in a particular location. The cumulative impacts to commercial fisheries would also be 

determined by other factors that could affect access to fishing sites or by impacts that could affect 

the supply and demand for seafood.

OCS Oil- and Gas-Related Impacts

A proposed action would contribute to the impacts from the routine activities and accidental 

events of the overall OCS Program. Chapter 4.7 discusses the cumulative impacts to fish 

populations from OCS oil- and gas-related sound, bottom-disturbing activities (Chapter 3.3.1.5), and 

habitat modification. These impact-producing factors could cause displacement, physical harm, or 

fatalities. The associated cumulative impacts to commercial fisheries would be determined by the 

intensity of commercial fishing for each species in an affected area (described in Chapter 4.10.1). 

In particular, impacts to fish populations could lead to decreased fishing landings and revenues, 

which would impact jobs and incomes throughout the seafood supply chain. A proposed action 

would also contribute to the space-use conflicts (Chapter 3.1.3.4.2) and the potential for accidental 

events (which are discussed above) arising from the OCS Program. Finally, the Deepwater Horizon

oil spill may still have some lingering impacts on commercial fisheries. Long-term impacts to fish 

populations as a result of past oil spills in the GOM have not been described, but impacts could be 

masked by natural variations in populations or may not be evident for several years. Chapter 4.10.1

describes that landings revenues for most species have generally recovered since the spill. 

However, there could still be minor lingering impacts for some fisheries (Greater New Orleans, Inc., 

2011).

A proposed lease sale would be relatively small when compared with all past, present, and 

future lease sales (Table 3-23). Therefore, the incremental cumulative impacts of a proposed action 

relative to the overall OCS Program would range from beneficial to minor. The exact impacts 
Description of the Affected Environment and Impact Analysis 4-319

would depend on the locations of activities, the species affected, the intensity of commercial fishing 

activity in the affected area, and the substitutability of any lost fishing access.

Non-OCS Oil- and Gas-Related Impacts

The non-OCS oil- and gas-related impacts that could have an effect on commercial fisheries 

including anthropogenic sound (Chapter 3.3.2.7) and habitat modifications, state oil and gas 

activities (Chapter 3.3.2.1), space-use conflicts, and various economic forces.

Chapter 4.7 discusses the impacts of anthropogenic sound and habitat modifications on fish

resources. These impacts would impact commercial fishing to the extent that landings of certain 

species were impacted, which would likely occur in proportion to the scale of commercial fishing in 

an area (Chapter 4.10.1).

State oil and gas activities also have impacts on commercial fisheries. For example, State 

oil and gas activities could lead to space-use conflicts with commercial fisheries and could lead to 

accidental events. State oil and gas platforms could also support reef fish populations important to 

commercial fishermen. The nature of these impacts would be similar to those of a proposed action, 

although the affected species may be different. For example, oysters and blue crab are primarily 

fished in State waters and thus could be impacted by the associated State oil and gas routine and 

accidental impacts.

Commercial fishermen also encounter space-use conflicts with recreational, commercial, and 

military vessels that temporarily restrict access to fishing areas. Although tropical storm events are a 

part of the natural environment and not considered to adversely impact fish populations, severe 

events could affect various types of infrastructure (e.g., vessels, fish houses, and suppliers) that 

support commercial fishing. Storms could also temporarily prevent fishermen from fishing in certain 

areas.

A proposed action should also be viewed in light of various economic forces affecting 

commercial fisheries. Participants in the GOM seafood industry compete with participants in various 

other domestic and international markets. The USDOC, NMFS (2015k) presents various statistics 

regarding these markets. For example, GOM shrimp competes with a large import market. In 2013, 

there were $5.3 billion of shrimp imports into the U.S., $4 billion of which came from Asian countries. 

Demand for GOM seafood is also positively correlated with the overall state of the economy; 

information regarding the expected progression of the economy is presented in Chapter 4.14.2. The 

cumulative impacts to commercial fisheries would also be influenced by the management strategies 

employed by the NOAA, the Gulf of Mexico Fishery Management Council, and various State 

agencies. For example, the NOAA and the Texas Parks and Wildlife Department annually close 

Federal and State waters to shrimp fishing for 45-90 days in late spring to ensure a healthy shrimp 

population (USDOC, NFMS, 2015l). Fisheries managers also develop strategies for species, such 

as red snapper, that are important to recreational and commercial fishing (USDOC, NFMS, 2015m). 

Finally, the NMFS has published the final rule for mechanisms to manage aquaculture in the Federal 
4-320 Gulf of Mexico Multisale EIS

Gulf of Mexico (Federal Register, 2016a). The NFMS has published a programmatic EIS for its Gulf 

of Mexico aquaculture management plan (USDOC, NMFS, 2009). Chapter 3.3.2.11 provides more 

information regarding aquaculture in the Gulf of Mexico. These various management strategies 

would likely sustain healthy commercial fisheries during the life of a proposed action.

A proposed action would be relatively small when compared with the non-OCS oil- and gasrelated factors discussed above (refer to Chapter 3). Therefore, the incremental cumulative impacts 

of a proposed action relative to these non-OCS oil- and gas-related factors would range from 

beneficial to minor. The exact impacts would depend on the locations of activities, the species 

affected, the intensity of commercial fishing activity in the affected area, and the substitutability of 

any lost fishing access.

Incomplete or Unavailable Information

BOEM has determined that there is incomplete or unavailable information related to 

commercial fisheries. Some of this incomplete or unavailable information relates to fish populations 

that support commercial fishing, which is discussed in Chapter 4.7. There is also incomplete or 

unavailable information regarding the long-term impacts of acute and chronic exposure to oil on 

commercial fisheries. This information is unavailable because these impacts would only become 

evident through time. In lieu of the incomplete or unavailable information, BOEM used various data 

sources and studies to estimate the affected environment and impacts of OCS oil- and gas-related 

and non-OCS oil- and gas-related activities for commercial fishing. BOEM has determined that the 

incomplete or unavailable information is not essential to a reasoned choice among alternatives 

because existing data sources are sufficient for BOEM to reasonably estimate impacts.

4.10.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

The impacts of Alternative A would correspond to the impacts discussed in Chapter 4.10.2. 

Alternative A could affect commercial fisheries by affecting fish populations or by affecting the 

socioeconomic aspects of commercial fishing. The impacts of a proposed action on fish populations 

are presented in Chapter 4.7. Routine activities such as seismic surveys, drilling activities, and 

service-vessel traffic can cause space-use conflicts with fishermen. Structure emplacement could 

have positive or negative impacts, depending on the location and species. Accidental events, such 

as oil spills, could cause fishing closures and have other impacts on the supply and demand for 

seafood. However, accidental events that could arise from a proposed action would likely be small 

and localized. Alternative A should also be viewed in light of the overall OCS Program, State oil and 

gas activities, overall vessel traffic, hurricanes, economic factors, and Federal and State fisheries 

management strategies. The incremental impacts of Alternative A on commercial fisheries are 

expected to range from beneficial to minor, largely due to the limited scale of a proposed action. 

The exact impacts would depend on the locations of activities, the species affected, the intensity of 

commercial fishing activity in the affected area, and the substitutability of any lost fishing access.
Description of the Affected Environment and Impact Analysis 4-321

4.10.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative B. There are some differences 

(described in Chapter 4.10.1) in the scales of commercial fishing in the CPA/EPA compared with the 

WPA. For example, menhaden and blue crab comprise larger percentages of landings revenues in 

the CPA/EPA (particularly in Louisiana) compared with the WPA. However, the impact conclusions 

for Alternatives A and B are the same.

The impacts of Alternative B would correspond to the impacts discussed in Chapter 4.10.2. 

Alternative B could affect commercial fisheries by affecting fish populations or by affecting the 

socioeconomic aspects of commercial fishing. The impacts of a proposed action on fish populations 

are presented in Chapter 4.7. Routine activities such as seismic surveys, drilling activities, and 

service-vessel traffic can cause space-use conflicts with fishermen. Structure emplacement could 

have positive or negative impacts, depending on the location and species. Accidental events, such 

as oil spills, could cause fishing closures and have other impacts on the supply and demand for 

seafood. However, accidental events that could arise from a proposed action would likely be small 

and localized. Alternative B should also be viewed in light of the overall OCS Program, State oil and 

gas activities, overall vessel traffic, hurricanes, economic factors, and Federal and State fisheries 

management strategies. The incremental impacts of Alternative B on commercial fisheries are 

expected to range from beneficial to minor, largely due to the limited scale of a proposed action. 

The exact impacts would depend on the locations of activities, the species affected, the intensity of 

commercial fishing activity in the affected area, and the substitutability of any lost fishing access.

4.10.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Alternative C entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative C. There are some differences 

(described in Chapter 4.10.1) in the scales of commercial fishing in the CPA/EPA compared with the 

WPA. For example, menhaden and blue crab comprise larger percentages of landings revenues in 

the CPA/EPA (particularly in Louisiana) compared with the WPA. Alternative C would also entail 

less overall activity than Alternative A. However, the impact conclusions for Alternatives A and C are 

the same.

The impacts of Alternative C would correspond to the impacts discussed in Chapter 4.10.2. 

Alternative C could affect commercial fisheries by affecting fish populations or by affecting the 

socioeconomic aspects of commercial fishing. The impacts of a proposed action on fish populations 

are presented in Chapter 4.7. Routine actions such as seismic surveys, drilling activities, and 

service vessel traffic can cause space-use conflicts with fishermen. Structure emplacement could 

have positive or negative impacts, depending on the location and species. Accidental events, such 

as oil spills, could cause fishing closures and have other impacts on the supply and demand for 

seafood. However, accidental events that could arise from a proposed action would likely be small 
4-322 Gulf of Mexico Multisale EIS

and localized. Alternative C should also be viewed in light of the overall OCS Program, State oil and 

gas activities, overall vessel traffic, hurricanes, economic factors, and Federal and State fisheries 

management strategies. The incremental impacts of Alternative C on commercial fisheries are 

expected to range from beneficial to minor, largely due to the limited scale of a proposed action. 

The exact impacts would depend on the locations of activities, the species affected, the intensity of 

commercial fishing activity in the affected area, and the substitutability of any lost fishing access.

4.10.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D entails leasing a subset of the area considered in Alternatives A, B, or C by 

making blocks that would normally be subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations unavailable for lease. 

Therefore, the analyses for those alternatives (described above) cover the potential impacts of 

Alternative D, generally to commercial fisheries. . In addition, Alternative D would not exclude large 

areas to commercial fishing. This is particularly true since fishermen would probably not use certain 

gear types, such as bottom trawls, near topographic features for fear of entangling and damage to 

gear. Therefore, the impact conclusions (which are discussed below) remain the same, though 

there may be a slight offsetting effect to commercial fishing in the excluded blocks, as it would 

reduce any potential conflict with OCS oil- and gas-related activities but would similarly prevent the 

potential for beneficial effects from new platforms or other fish attractions in the blocks.

The impacts of Alternative D would correspond to the impacts discussed in Chapter 4.10.2. 

Alternative D could affect commercial fisheries by affecting fish populations or by affecting the 

socioeconomic aspects of commercial fishing. The impacts of a proposed action on fish populations 

are presented in Chapter 4.7. Routine actions such as seismic surveys, drilling activities, and 

service vessel traffic can cause space-use conflicts with fishermen. Structure emplacement could 

have positive or negative impacts, depending on the location and species. Accidental events, such 

as oil spills, could cause fishing closures and have other impacts on the supply and demand for 

seafood. However, accidental events that could arise from a proposed action would likely be small 

and localized. Alternative D should also be viewed in light of the overall OCS Program, State oil and 

gas activities, overall vessel traffic, hurricanes, economic factors, and Federal and State fisheries 

management strategies. The incremental impacts of Alternative D on commercial fisheries are 

expected to range from beneficial to minor, largely due to the limited scale of a proposed action. 

The exact impacts would depend on the locations of activities, the species affected, the intensity of 

commercial fishing activity in the affected area, and the substitutability of any lost fishing access.

4.10.2.5 Alternative E—No Action

Alternative E would prevent the beneficial to minor impacts discussed in Chapter 4.10.2. 

However, commercial fisheries would still be subject to the impacts from the OCS Program, as well 

as the impacts from the non-OCS oil- and gas-related sources discussed above. 
Description of the Affected Environment and Impact Analysis 4-323

4.11 RECREATIONAL FISHING

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

with a proposed lease sale and a proposed lease sale’s incremental contribution to the cumulative 

impacts to recreational fishing are presented in this chapter. The approach of the analysis is to 

focus on the potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., 

exploration, development, and production), as well as the accidental events and cumulative impacts, 

and to define the impact-level measures for each impact-producing factor. The analysis in this 

chapter relies on the analysis and conclusions reached in Chapter 4.7 (Fish and Invertebrate 

Resources). This chapter carries the cause and effect analysis to the social endpoint for 

recreational fishing. Therefore, in general, the impact-producing factors identified in Chapter 4.7

would have the potential to impact recreational fishing as well.

In this chapter (and in the analyses of the alternatives), the impact measures are defined in 

terms of the intensity, duration, and geographical extent of the impacts to the human uses of 

recreational fisheries along the Gulf Coast. In particular, the impacts of each impact-producing 

factor are summarized in Table 4-17 using the impact-level measures below.

Impact-Level Definitions

• Beneficial – Impacts would be beneficial.

• Negligible – Little or no detectable impact.

• Minor – Impacts are detectable but less than severe.

• Moderate – Impacts are severe but are short term and/or not extensive.

• Major – Impacts are long term, extensive, and severe.

Table 4-17. Recreational Fishing Impact Producing Factors.

Recreational Fishing Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Anthropogenic Sound Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Bottom-Disturbing 

Activities Negligible Negligible Negligible Negligible None

Space-Use Conflicts Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Production Structure 

Emplacement and 

Removal

Beneficial to Beneficial to Beneficial to Beneficial to

None

Minor Minor Minor Minor

Accidental Impacts

Oil Spills Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor
4-324 Gulf of Mexico Multisale EIS

Recreational Fishing Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Cumulative Impacts

OCS Oil and Gas

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible

Minor Minor Minor Minor

Non OCS Oil and Gas

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible Minor Minor Minor Minor

4.11.1 Description of the Affected Environment

Recreational fishing is a popular pastime in many parts of the Gulf of Mexico. The GOM’s 

extensive estuarine habitats (Chapter 4.3.1), live bottom habitats (Chapter 4.6), and artificial 

substrates (including artificial reefs, shipwrecks, and oil and gas platforms) support several valuable 

recreational fisheries. Fisheries are managed by NOAA Fisheries (NMFS), as advised by the 

regional fisheries management councils; details regarding the most recent regulatory mechanisms 

relevant to recreational fishing are described by the Gulf of Mexico Fishery Management Council 

(2015). Recreational landings and effort data for Louisiana, Mississippi, Alabama, and Florida are 

provided by the NMFS; recreational fishing data for Texas is provided by the Texas Parks and 

Wildlife Department. Although a proposed lease sale is a regionwide lease sale, the data from these 

two sources are presented separately to allow for methodological differences between them. These 

data, along with data on the economic impacts of recreational fishing, are presented in subsequent 

sections. The biological aspects of the affected environment are discussed in Chapter 4.7 (Fishes 

and Invertebrate Resources).

CPA/EPA Catch and Effort Data

The NMFS collects and provides public access to data on recreationally targeted species, 

landings, and angler effort (USDOC, NMFS, 2014b). The NMFS also publishes annual reports 

summarizing these data and the economic impacts to the Gulf Coast States (USDOC, NMFS, 

2014a). Table 4-18 present data on the number of angler trips taken in Louisiana, Mississippi, 

Alabama, and West Florida from 2008 to 2013. The total number of angler trips in these four states 

declined from 2008 through 2010, but then gradually increased from 21 million trips in 2010 to 

25.2 million trips in 2013. In 2013, there were 15.9 million angler trips in West Florida, 4.7 million 

angler trips in Louisiana, 2.9 million angler trips in Alabama, and 1.8 million angler trips in 

Mississippi. Tables 4-18 also breaks down these trips by location and mode. The three geographic 

locations for each state are inland, State ocean waters, and Federal ocean waters. The three 

modes of fishing are shore fishing, charter fishing, and private/rental fishing. The last column in 

Table 4-18 present the percentage of recreational fishing in 2013 broken down by location and 

mode. The least amount of recreational fishing occurs in Federal waters, where most OCS oil- and 

gas-related activities occur. In the four states combined in 2013, 59.7 percent of recreational fishing 

occurred in inland waters, 32.7 percent occurred in State ocean waters, and 7.6 percent occurred in 

Federal ocean waters. In 2013, 53.5 percent of recreational fishing occurred on private or rental 

boats, 42.9 percent occurred from shore, and 3.6 percent occurred on charter boats.
Description of the Affected Environment and Impact Analysis 4-325

Table 4-18. CPA and EPA Effort Data: Angler Trips in the Gulf of Mexico.

Area 2008 2009 2010 2011 2012 2013

% of 

State 

Total in 

2013

Alabama

Shore Ocean 

(< 3 nmi) 249,893 322,126 447,041 603,546 750,159 1,250,811 43.70%

Shore Inland 452,192 449,470 365,234 598,700 461,221 515,982 18.03%

Charter Ocean 

(<3 nmi) 9,967 9,166 8,860 19,874 15,785 20,615 0.72%

Charter Ocean 

(>3 nmi) 38,046 36,259 17,424 48,616 28,340 56,145 1.96%

Charter Inland 7,700 10,656 7,221 6,351 14,536 12,976 0.45%

Private/Rental Ocean 

(<3 nmi) 247,876 131,997 114,816 191,563 137,321 118,801 4.15%

Private/Rental Ocean 

(>3 nmi) 74,074 134,411 69,335 188,994 131,897 278,821 9.74%

Private/Rental Inland 624,197 618,502 656,226 825,821 766,027 608,280 21.25%

Total 1,703,945 1,712,587 1,686,157 2,483,465 2,305,286 2,862,431 

West Florida

Shore Ocean 

(< 9 nmi) 3,076,591 2,688,011 1,610,807 1,982,194 2,199,810 3,745,909 23.49%

Shore Inland 3,704,990 3,793,756 4,034,208 3,862,665 4,016,544 3,191,414 20.01%

Charter Ocean

(<9 nmi) 187,810 196,753 159,317 179,880 242,666 199,908 1.25%

Charter Ocean 

(>9 nmi) 255,300 262,005 203,201 236,088 307,121 322,185 2.02%

Charter Inland 127,801 113,842 98,440 119,826 149,315 161,479 1.01%

Private/Rental Ocean

(<9 nmi) 3,624,073 2,605,196 2,257,349 1,901,217 2,087,991 2,572,325 16.13%

Private/Rental Ocean 

(>9 nmi) 1,242,935 751,869 681,551 500,067 755,470 1,136,161 7.12%

Private/Rental Inland 5,277,665 5,265,888 5,221,323 5,118,740 5,021,267 4,619,920 28.97%

Total 17,497,165 15,677,320 14,266,196 13,900,677 14,780,184 15,949,301

Louisiana

Shore Ocean 

(< 3 nmi) 62,712 38,930 11,664 48,893 152,094 247,502 5.31%

Shore Inland 870,042 730,053 717,006 1,073,035 978,657 1,101,517 23.63%

Charter Ocean 

(<3 nmi) 10,468 3,931 2,762 6,937 3,646 5,058 0.11%

Charter Ocean 

(>3 nmi) 32,805 21,173 8,106 15,742 19,827 15,373 0.33%

Charter Inland 135,915 157,692 68,018 90,057 91,192 101,935 2.19%

Private/Rental Ocean

(<3 nmi) 97,797 81,008 59,347 77,986 116,854 82,512 1.77%

Private/Rental Ocean 

(>3 nmi) 89,859 99,352 11,568 80,952 88,503 65,730 1.41%

Private/Rental Inland 3,320,459 2,995,875 2,984,016 3,182,645 2,685,791 3,041,527 65.25%

Total 4,620,057 4,128,014 3,862,487 4,576,247 4,136,564 4,661,154 
4-326 Gulf of Mexico Multisale EIS

Area 2008 2009 2010 2011 2012 2013

% of 

State 

Total in 

2013

Mississippi

Shore Ocean 

(< 3 nmi) 0 143 0 0 811 0 0.00%

Shore Inland 359,438 309,612 596,544 760,788 947,075 763,983 43.39%

Charter Ocean 

(<3 nmi) 4,286 2,803 904 3,123 1,628 2,190 0.12%

Charter Ocean 

(>3 nmi) 718 330 949 221 125 153 0.01%

Charter Inland 8,229 7,656 4,989 7,891 9,738 8,911 0.51%

Private/Rental Ocean 

(<3 nmi) 12,056 16,962 12,419 18,682 4,116 6,124 0.35%

Private/Rental Ocean 

(>3 nmi) 28,007 26,316 4,626 12,974 41,137 53,886 3.06%

Private/Rental Inland 555,951 715,505 612,162 811,711 945,819 925,512 52.56%

Total 968,685 1,079,327 1,232,593 1,615,390 1,950,449 1,760,759 

Gulf Total CPA and EPA Effort Data

Shore Ocean 

(< 3 nmi) 3,389,196 3,049,210 2,069,512 2,634,633 3,102,874 5,244,222 20.78%

Shore Inland 5,386,662 5,282,891 5,712,992 6,295,188 6,403,497 5,572,896 22.09%

Charter Ocean 

(<3 nmi) 212,531 212,653 171,843 209,814 263,725 227,771 0.90%

Charter Ocean 

(>3 nmi) 326,869 319,767 229,680 300,667 355,413 393,856 1.56%

Charter Inland 279,645 289,846 178,668 224,125 264,781 285,301 1.13%

Private/Rental Ocean 

(<3 nmi) 3,981,802 2,835,163 2,443,931 2,189,448 2,346,282 2,779,762 11.02%

Private/Rental Ocean 

(>3 nmi) 1,434,875 1,011,948 767,080 782,987 1,017,007 1,534,598 6.08%

Private/Rental Inland 9,778,272 9,595,770 9,473,727 9,938,917 9,418,904 9,195,239 36.44%

Total 24,789,852 22,597,248 21,047,433 22,575,779 23,172,483 25,233,645

Source: USDOC, NMFS, 2014a.

Table 4-19 presents data on the most commonly landed species by recreational fishermen in 

Louisiana, Mississippi, and Alabama combined from 2008 to 2013. Some of the most popular 

recreational species in these states are spotted seatrout (Cynoscion nebulosus), red drum 

(Sciaenops ocellatus), Atlantic croaker (Micropogonias undulatus), sand seatrout (Cynoscion 

arenarius), Spanish mackerel (Scomberomorus maculatus), and black drum (Pogonias cromis). In 

2013, landings of most species were similar to landings observed in prior years. However, there 

were noticeable increases in landings of red drum, black drum, and red snapper; there were 

noticeable decreases in landings of sand seatrout and Spanish mackerel. 
Description of the Affected Environment and Impact Analysis 4-327

Table 4-19. CPA and EPA Catch Data: Fish Species Caught by Recreational Anglers from 2008 

through 2013 in Louisiana, Mississippi, and Alabama Combined.

Species/Year 2008 2009 2010 2011 2012 2013

Atlantic Croaker 4,648,460 4,696,500 4,907,698 7,461,690 4,757,605 4,562,458

Black Drum 1,819,040 1,645,416 1,544,695 1,768,605 1,629,633 2,472,942

Blackfin Tuna 57,274 59,046 1,793 33,008 64,007 35,705

Cobia 31,484 21,575 3,519 50,263 25,105 40,448

Dolphins 96,899 7,200 2,174 911 9,418 31,524

Gag 45,383 42,835 10,274 13,523 12,939 20,573

Gray Snapper 233,841 255,943 33,479 142,062 451,724 375,596

Great Amberjack 29,728 28,422 16,982 56,163 15,962 30,410

King Mackerel 35,373 82,508 38,069 70,898 124,839 124,211

Little Tuny 18,529 9,520 14,175 28,660 40,005 17,172

Pinfishes 474,606 454,356 521,732 1,460,956 1,101,630 1,227,257

Red Drum 7,292,431 6,467,215 7,486,800 6,809,940 6,305,267 9,009,223

Red Grouper 12 774 2,296 0 168 2,326

Red Snapper 905,870 894,732 368,901 851,662 607,516 1,743,402

Sand Seatrout 4,052,323 5,294,998 5,715,702 7,115,540 5,194,418 3,768,286

Sheepshead 1,643,546 1,422,352 1,183,531 1,966,957 1,163,684 1,334,601

Southern 

Flounder 557,809 825,776 982,237 964,675 1,016,969 1,320,715

Southern Kingfish 1,350,161 1,190,382 1,045,644 1,075,935 760,688 1,180,114

Spanish Mackerel 196,011 200,662 397,247 541,435 844,101 2,525,453

Spotted Seatrout 24,013,172 21,657,958 15,118,683 19,843,879 20,452,196 22,327,595

Striped Mullet 322,245 293,375 866,308 1,412,632 1,163,763 1,623,070

White Grunt 0 1,084 0 0 0 0

Source: USDOC, NMFS, 2014a.

Table 4-20 presents data on the species most commonly landed by recreational fishermen in 

West Florida from 2008 to 2013. These species include pinfish (Lagodon rhomboides), spotted 

seatrout, gray snapper (Lutjanus griseus), Spanish mackerel, white grunt (Haemulon plumieri), and 

red grouper (Epinephelus morio). In 2013, landings of most species were similar to landings 

observed in prior years. However, there were noticeable increases in landings of dolphins, gray 

snapper, and Spanish mackerel; there were noticeable decreases in landings of sand seatrout and 

spotted seatrout.

Table 4-20. CPA and EPA Catch Data: Fish Species Caught by Recreational Anglers from 2008 

through 2013 in West Florida.

Species/Year 2008 2009 2010 2011 2012 2013

Atlantic Croaker 372,271 333,201 429,614 488,456 468,451 437,425

Black Drum 156,391 125,064 218,938 115,842 112,817 219,579

Blackfin Tuna 80,613 25,933 30,354 20,821 44,190 56,765

Cobia 128,670 64,532 58,880 59,124 69,045 71,391

Dolphins 543,588 394,692 267,944 455,918 359,146 1,922,167
4-328 Gulf of Mexico Multisale EIS

Species/Year 2008 2009 2010 2011 2012 2013

Gag 4,511,351 2,926,723 2,250,467 1,255,515 1,112,826 1,382,809

Gray Snapper 7,082,879 4,190,312 2,418,388 2,658,705 4,073,840 6,618,012

Great Amberjack 219,182 183,807 365,690 194,791 151,623 327,080

King Mackerel 338,965 591,022 252,995 173,914 242,302 291,727

Little Tuny 185,031 158,836 126,299 173,102 296,492 157,557

Pinfishes 15,637,922 9,422,451 9,893,857 7,390,804 12,258,510 9,675,256

Red Drum 3,017,880 1,665,659 2,231,738 3,182,220 2,713,322 2,560,823

Red Grouper 3,105,147 3,171,464 2,240,450 2,009,532 2,009,920 3,166,786

Red Snapper 1,883,804 2,046,716 1,400,636 1,189,850 1,408,331 2,322,435

Sand Seatrout 1,282,681 1,337,450 613,338 1,152,573 2,157,703 899,277

Sheepshead 1,412,235 1,489,548 1,700,583 1,882,258 1,805,203 1,608,128

Southern Flounder 37,117 11,332 9,522 23,120 33,346 28,887

Southern Kingfish 240,040 227,140 404,764 87,367 74,894 93,384

Spanish Mackerel 3,742,003 2,938,091 3,643,511 2,934,531 2,434,336 4,986,910

Spotted Seatrout 11,127,967 9,042,259 9,584,787 12,856,960 12,545,581 9,165,609

Striped Mullet 1,083,471 674,022 925,554 801,743 1,395,641 1,555,565

White Grunt 3,721,050 2,283,923 2,494,075 2,852,807 3,405,536 4,701,436

Source: USDOC, NMFS, 2014a.

WPA Catch and Effort Data

Table 4-21 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 (Fisher, official 

communication, 2015). There were 1,069,125 angler trips in 2014, down from 1,159,187 in 2012 

and 1,149,597 in 2013. The least amount of recreational fishing occurs in Federal waters, where 

most OCS oil- and gas-related activities occur. In 2014, 96.4 percent of fishing occurred in bays, 

2.4 percent occurred in State ocean waters (Texas Territorial Sea), and 1.2 percent occurred in 

Federal ocean waters. The percentage of fishing in Federal waters has been declining during recent 

years. Texas divides its data into two fishing seasons: Season A (November 21-May 14) and 

Season B (May 15-November 20). In 2014, 69.3 percent of angler trips occurred in Season B, and 

12.9 percent of trips occurred by charter boats. In recent years, fishing during Season A has been 

gradually declining, while fishing during Season B has been relatively stable.

Tables 4-21 and 4-22 provide 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. The most 

popular species in bays include spotted seatrout, red drum, black drum, and Atlantic croaker. Red 

snapper (Lutjanus campechanus) and king mackerel (Scomberomorus cavalla) are the most popular 

species in Federal waters. The 2014 landings of most species were in the ranges observed in prior 

years, although landings of spotted seatrout were noticeably lower in 2014 than during prior years.
Description of the Affected Environment and Impact Analysis 4-329

Table 4-21. Texas Effort Data: Number of Angler Trips from 2009 through 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 87,972 711,885 919,368 121,6591,041,027

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 29,842 360,303 576,735 122,855 699,590 907,196 152,6971,059,893

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 35,471 382,186 616,245 126,969 743,214 962,960 162,4401,125,400

2012

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 331,889 87,696 419,585 563,656 134,502 698,158 895,545 222,1981,117,743

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 88,868 429,590 591,699 137,898 729,597 932,421 226,7661,159,187

2013

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 350,918 39,054 389,972 613,508 101,135 714,643 964,426 140,1891,104,615

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 1,004,861 144,7351,149,597

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
4-330 Gulf of Mexico Multisale EIS

EEZ = Exclusive Economic Zone; TTS = Texas Territorial Sea

(1) Season A is November 21 - May 14 and Season B is May 15 - November 20.

(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 that is counted as multiple trips.

Source: Fisher, official communication, 2015.

Table 4-22. Texas Catch Data: 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 1,137 810 795 590 Spotted Seatrout 789 721 1,119 798 789 585

Panel C: Landings in State Waters Panel D: Landings in the Exclusive Economic Zone

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 – – 

(1) Fish landings are presented in thousands of fish.

(2) The TPWD 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 reflects combined catch for Seasons A and B. For example, 

the catch data for 2013 reflect catch from November 21, 2012, to November 20, 2013.

Source: Fisher, official communication, 2015.

Economic Impacts of Recreational Fishing

Recreational fishing can affect regional economies in various ways. Most directly, anglers 

affect the economy through spending on fishing-related goods and services. This direct spending 
Description of the Affected Environment and Impact Analysis 4-331

includes trip expenditures and expenditures on durable equipment. Direct angler spending supports 

firms in related industries along an economy’s supply chain. In addition, spending by fishermen 

serves as income to other actors in an economy, which supports overall spending patterns. The 

NMFS conducted an analysis that quantified this dependence of regional economies on recreational 

fishing activity (USDOC, NMFS, 2014a); this analysis utilized the techniques of an earlier study by 

Gentner and Steinback (2008). These studies utilized input-output economic models, which create 

multipliers that predict the sales, value-added, and jobs that result from direct angler spending. The 

levels of value-added and employment supported by recreational fishing in each Gulf Coast State in 

2012 are listed below.

• West Florida ($5,259,726,000; 75,268 jobs)

• Louisiana ($1,099,216,000; 16,972 jobs)

• Texas ($1,005,040,000; 13,944 jobs)

• Alabama ($425,328,000; 7,501 jobs) 

• Mississippi ($85,497,000; 1,649 jobs)

4.11.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

recreational fishing that would arise from projected activities from a proposed lease sale are 

analyzed in this chapter. While there are some differences in the amount of activities associated 

with the alternatives, many of the impacts associated with the alternatives are similar. Therefore, 

this chapter will describe the impacts that are expected to apply to all alternatives, while any 

deviations from these impact conclusions will be discussed in Chapters 4.11.2.1-4.11.2.5. 

Routine Activities

Routine OCS oil and gas operations (such as anthropogenic sound, bottom disturbances 

service-vessel traffic, and production structure emplacement) can affect recreational fisheries by 

impacting populations of recreationally targeted species. The impacts of anthropogenic sound and 

short-term bottom disturbances on fish populations are discussed in Chapter 4.7 (Fish and 

Invertebrate Resources). The corresponding impacts of anthropogenic sound on recreational fishing 

would be negligible to minor because disruptions to fish populations could reduce landings in 

proportion to the amount of recreational fishing activities in an area (refer to Chapter 4.11.1). The 

exact impacts would depend on the locations of activities, the species affected, the intensity of 

recreational fishing activity in the affected area, and the substitutability of any lost fishing access. 

The impacts of short-term bottom disturbances on recreational fishing are expected to be negligible

because the impacts to fish populations would similarly be negligible and because most 

recreational fishing does not target bottom-dwelling species that are more likely to be impacted by 

these disturbances.
4-332 Gulf of Mexico Multisale EIS

The OCS oil- and gas-related vessel traffic could also cause space-use conflicts with 

recreational fishermen. The OCS vessel traffic would occur between ports that service the offshore 

industry and drilling and production facilities in Federal waters. However, there is limited spatial 

overlap between recreational fishing and oil and gas ports. In addition, most recreational fishing 

activities in the Gulf of Mexico occur inland or in State waters. Finally, recreational vessels can often 

easily avoid temporary OCS vessel traffic. Therefore, the impacts of OCS oil- and gas-related 

vessel traffic on recreational fishing are expected to be negligible to minor. The exact impacts 

would depend on the locations of activities, the species affected, the intensity of recreational fishing 

activity in the affected area, and the substitutability of any lost fishing access.

The installation of production platforms can enhance recreational fishing opportunities 

because platforms often attract recreationally important species. Hiett and Milon (2002) estimate 

that 20.2 percent of private boat fishing, 32.2 of charter boat fishing, and 50.9 percent of party boat 

fishing in Texas, Louisiana, Mississippi, and Alabama combined occur within 300 ft (91 m) of an oil 

or gas structure in State or Federal waters. However, the removal of a platform would preclude its 

use for recreational fishing unless it is redeployed as artificial reef substrate as part of an artificial 

reef program (Chapter 3.1.9.1). The BSEE presents more information regarding the status of Rigsto-Reefs activities in the Gulf of Mexico (USDOI, BSEE, 2015h). Ajemian et al. (2015) analyze the 

fish community structures at operational platforms, decommissioned platforms that were reefed 

using a variety of methods, and Liberty Ships (World War II era ships that now serve as artificial 

reefs) offshore Texas. This study found that recreationally important species such as red snapper 

were prevalent among all types of platform structures, suggesting that the reefing of a platform could 

maintain some of the properties desired by recreational fishermen. A proposed lease sale would 

likely have negligible to minor impacts on recreational fishing because of the limited amount of 

activity that occurs in Federal waters (Chapter 4.11.1) and because the positive and negative effects 

of routine OCS oil- and gas-related activities that modify habitat (i.e., infrastructure emplacement 

and decommissioning) would partially offset each other.

Accidental Events

Oil spills can arise from accidents with respect to vessels, pipelines, drilling operations, or 

production operations. Oil spills can lead to localized fishing closures that could directly impact 

fishermen’s access to fish resources. The potential impacts of oil spills on fish populations that 

support recreational fishing are described in Chapter 4.7 (Fish and Invertebrate Resources). The 

corresponding impacts to recreational fishing would depend on the types and scales of recreational 

fishing activities in an impacted area, which are discussed in Chapter 4.11.1. For example, red 

snapper is a popular recreational species that is prevalent near oil and gas platforms. Therefore, an 

oil spill that occurred near a platform could impact recreational fishing for red snapper and other reef 

fish, at least in the short term. An oil spill could also dissuade anglers if it affected the aesthetics of 

fishing in an area. For example, anglers could be dissuaded by perceived oil in water, tainted fish 

populations, or response activities. Reductions in recreational fishing could also impact the various 

firms that supply goods and services to anglers. Gentner Consulting Group (2010) presents a 

methodology for estimating the economic impacts of an oil spill in the Gulf of Mexico that entails 
Description of the Affected Environment and Impact Analysis 4-333

estimating State-level recreational fishing levels and then scaling these levels by the size and 

duration of a closure area. However, these economic impacts would likely be negligible to minor

because an oil spill arising from a proposed lease sale would likely be small and localized, leaving 

recreational fishermen numerous alternative fishing sites. The exact impacts would depend on the 

locations of oil spills, the species affected, the intensity of recreational fishing activity in the affected 

area, and the substitutability of any lost fishing access. In addition, as shown in the effort and 

landings data above, recreational fishing activity recovered fairly quickly in the aftermath of the 

Deepwater Horizon explosion, oil spill, and response which was a much larger spill than is 

anticipated to arise from a proposed lease sale.

Cumulative Impacts

A proposed lease sale would contribute to the impacts of the overall OCS Program, as well 

as the impacts of various non-OCS sources. The cumulative analysis will describe these various

impacts, and will then reach impact conclusions regarding the incremental impacts of a proposed 

lease sale relative to these OCS and non-OCS sources.

OCS Oil- and Gas-Related Impacts

A proposed lease sale would add to the impacts to fish populations from sound and shortterm bottom disturbances (refer to Chapter 4.7, Fish and Invertebrate Resources). As discussed 

above, these would have impacts to recreational fishing to the extent that angler effort and species’ 

landings are impacted. A proposed lease sale would also add to the space-use conflicts with 

recreational fishermen that arise from the OCS Program. The proposed lease sale would also add 

to the potential for accidental events, such as oil spills, arising from the OCS Program. The scales 

of these impacts are similar as to those discussed above, but they would be proportionally higher to 

the larger scale of the OCS Program compared with a proposed lease sale.

As discussed above, oil and gas platforms generally enhance opportunities for recreational 

fishing. Conversely, structure removals prevent the use of those structures for recreational fishing. 

The number of platforms in the Federal Gulf of Mexico fell from a peak of 4,049 in 2001 to 2,634 in 

2013, which has reduced opportunities for recreational fishing in certain areas (USDOI, BSEE, 

2015i). However, anglers still have numerous places to fish, including artificial reefs (some of which 

have been created out of decommissioned platforms) and natural habitat features. The baseline for 

this cumulative analysis corresponds to the case in which a proposed lease sale does not occur. A 

proposed lease sale would initially have positive incremental impacts on recreational fishing because 

more structures would be installed than if the lease sale did not occur. The eventual removals would 

offset those impacts unless some structures were maintained through Rigs-to-Reefs programs 

(discussed above and in Chapter 3.1.9.1).

Relative to the overall OCS Program (i.e., all past, present, and future lease sales), a 

proposed lease sale would have beneficial (due to fish attraction at platforms and the potential use 

of decommissioned platforms as rigs-to-reefs) to minor incremental impacts (due to space-use 
4-334 Gulf of Mexico Multisale EIS

conflicts and impacts to fish populations) on recreational fishing activities because of the limited 

amount of activity and because the positive and negative effects would partially offset each other.

Non-OCS Oil- and Gas-Related Impacts

A proposed lease sale would contribute to the impacts of oil and gas activities in State 

waters, which are described in Chapter 3.3.2.1. The nature of these impacts would be similar to 

activities in Federal waters, although the impacts on recreational fishing depend on the intensity and 

species sought in a particular area. As discussed in Chapter 4.11.1, 1.3 percent of recreational 

fishing in Texas occurs in Federal waters, while 7.6 percent of angler effort in the four other Gulf 

Coast States combined occurs in Federal waters.

Recreational fishing in the Gulf of Mexico also encounters space-use conflicts with 

recreational, commercial, and military vessels. Marinevesseltraffic.com (2015) provides maps of 

current and historical vessel traffic in the Gulf of Mexico. There is a large amount of vessel traffic in 

the Gulf of Mexico, particularly near major ports. This vessel traffic causes various localized 

conflicts with recreational fishermen.

Hurricanes can impact boats and other infrastructure that support recreational fishing. 

Recreational fishing would also be affected by any impact-producing factor, such as a non-OCS oiland gas-related accidental event, that affects the aesthetics of a particular fishing site. Recreational 

fishing would also be positively correlated with general trends in tourism (discussed in Chapter 4.12, 

Recreational Resources) and the overall economy (discussed in Chapter 4.14.2, Economic 

Factors). Finally, recreational fishing regulations (discussed in Chapter 4.11.1) would likely maintain 

stable recreational fishing activities during the life of a proposed lease sale.

A proposed lease sale would have beneficial (due to fish attraction at platforms and the 

potential use of decommissioned platforms as rigs-to-reefs) to minor (due to space-use conflicts and 

impacts to fish populations) incremental impacts on recreational fishing activities because it would 

be small relative to these broader issues impacting recreational fishing.

Incomplete or Unavailable Information

BOEM has identified incomplete or unavailable information regarding the extent to which 

recreational fishing is dependent upon OCS platforms, as well as on the site-specific determinants of 

this dependency. BOEM is planning to undertake a study to examine these issues, although the 

results from this study project would not be released in the timeline contemplated in the NEPA 

analysis for this Multisale EIS. In lieu of this incomplete or unavailable information, BOEM used 

existing information and reasonably accepted scientific methodologies. For example, BOEM used 

data on recreational fishing activity provided by the Texas Parks and Wildlife Department and the 

NMFS to examine trends in recreational fishing in various areas. BOEM has also used information 

from Heitt and Milon (2002) and Ajemian et al. (2015), which provide some information on the scale 

and location of platform-dependent recreational fishing. BOEM does not expect the incomplete or 

unavailable information to significantly change its estimates of the impacts of the OCS Program on 
Description of the Affected Environment and Impact Analysis 4-335

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.

4.11.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

The impacts of Alternative A would correspond to the impacts discussed in Chapter 4.11.2. 

Namely, a proposed lease sale could affect recreational fishing by affecting fish populations or by 

affecting the socioeconomic aspects of recreational fishing. The impacts of Alternative A on fish 

populations are presented in Chapter 4.7 (Fish and Invertebrate Resources) and include impacts 

due to anthropogenic sound, short-term bottom disturbances, and habitat modifications. Vessel 

traffic arising from the Alternative A could cause space-use conflicts with anglers. Structure 

emplacement generally enhances recreational fishing, although this positive effect would be offset 

during decommissioning unless a structure was maintained as an artificial reef. Accidental events, 

such as oil spills, could cause fishing closures and affect the aesthetics of fishing in an area. 

However, accidental events that could arise from Alternative A would likely be negligible or minor 

and would be localized. Alternative A should also be viewed in light of overall trends in OCS 

platform decommissioning, State oil and gas activities, overall vessel traffic, hurricanes, economic 

factors, and Federal and State fisheries management strategies. The incremental impacts of 

Alternative A on recreational fisheries are expected to be negligible to minor because of the 

relatively small scale of a proposed lease sale and because the positive and negative effects would 

partially offset each other. The exact impacts would depend on the locations of activities, the 

species affected, the intensity of recreational fishing activity in the affected area, and the 

substitutability of any lost fishing access.

4.11.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B entails leasing only in the CPA/EPA, which is a subset of the area considered 

in Alternative A. Therefore, the analysis of Alternative A covers the potential impacts of Alternative 

B. There are some differences (described in Chapter 4.11.1) in the types and scales of recreational 

fishing in the WPA compared with the CPA/EPA. For example, 1.2 percent of recreational fishing in 

Texas occurs in Federal waters, while 7.6 percent of recreational fishing in the other Gulf Coast 

States combined occurs in Federal waters. However, these differences are not large enough to 

change the impact conclusions (discussed below) for Alternatives A and B. This is because 

Alternative B entails conducting most of the OCS oil- and gas-related activities proposed under 

Alternative A.

A proposed lease sale under Alternative B could affect recreational fishing by affecting fish 

populations or by affecting the socioeconomic aspects of recreational fishing. The impacts of 

Alternative B on fish populations are presented in Chapter 4.7 (Fish and Invertebrate Resources); 

these include impacts due to anthropogenic sound, short-term bottom disturbances, and habitat 

modifications. Vessel traffic arising from Alternative B could cause space-use conflicts with anglers. 

Structure emplacement generally enhances recreational fishing, although this positive effect would 
4-336 Gulf of Mexico Multisale EIS

be offset during decommissioning unless a structure were maintained as an artificial reef. Accidental 

events, such as oil spills, could cause fishing closures and affect the aesthetics of fishing in an area. 

However, accidental events that could arise from Alternative B would likely be negligible or minor 

and would be localized. Alternative B should also be viewed in light of overall trends in OCS 

platform decommissioning, State oil and gas activities, overall vessel traffic, hurricanes, economic 

factors, and Federal and State fisheries management strategies. The incremental impacts of 

Alternative B on recreational fisheries are expected to be negligible to minor because of the 

relatively small scale of a proposed lease sale and because the positive and negative effects to 

recreational fishing would partially offset each other. The exact impacts would depend on the 

locations of activities, the species affected, the intensity of recreational fishing activity in the affected 

area, and the substitutability of any lost fishing access.

4.11.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Alternative C entails leasing only in the WPA, which is a subset of the area considered in 

Alternative A. Therefore, the analysis of Alternative A covers the potential impacts of Alternative C. 

There are some differences (described in Chapter 4.11.1) in the types and scales of recreational 

fishing in the WPA compared with the CPA/EPA. For example, 1.2 percent of recreational fishing in 

Texas occurs in Federal waters, while 7.6 percent of recreational fishing in the other Gulf Coast 

States combined occurs in Federal waters. In addition, a proposed WPA lease sale would likely 

entail less oil and gas activities than a proposed CPA lease sale. However, these differences are 

not large enough to change the impact conclusions (discussed below) for Alternatives A and C. In 

particular, while there would be fewer OCS oil- and gas-related activities associated with Alternative 

C than with Alternative A, there could still be detectable (but less than severe) impacts under 

Alternative C.

A proposed lease sale under Alternative C could affect recreational fishing by affecting fish 

populations or by affecting the socioeconomic aspects of recreational fishing. The impacts of 

Alternative C on fish populations are presented in Chapter 4.7 (Fish and Invertebrate Resources) 

and include impacts due to anthropogenic sound, short-term bottom disturbances, and habitat 

modifications. Vessel traffic arising from Alternative C could cause space-use conflicts with anglers. 

Structure emplacement generally enhances recreational fishing, although this positive effect would 

be offset during decommissioning unless a structure were maintained as an artificial reef. Accidental 

events, such as oil spills, could cause fishing closures and affect the aesthetics of fishing in an area. 

However, accidental events that could arise from Alternative C would likely be negligible or minor 

and would be localized. Alternative C should also be viewed in light of overall trends in OCS 

platform decommissioning, State oil and gas activities, overall vessel traffic, hurricanes, economic 

factors, and Federal and State fisheries management strategies. The incremental impacts of 

Alternative C on recreational fisheries are expected to be negligible to minor because of the 

relatively small scale of a proposed lease sale under Alternative C and because the positive and 

negative effects to recreational fishing would partially offset each other. The exact impacts would 
Description of the Affected Environment and Impact Analysis 4-337

depend on the locations of activities, the species affected, the intensity of recreational fishing activity 

in the affected area, and the substitutability of any lost fishing access.

4.11.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D entails leasing a subset of the area considered in Alternatives A, B, or C by 

making blocks that would normally be subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations unavailable for lease. 

Alternative D would not exclude large areas to recreational fishing or exclude large areas from 

leasing (refer to Chapter 4.12.1). Therefore, the analyses for those alternatives (described above) 

cover the potential impacts of Alternative D, generally to recreational fisheries. Therefore, the 

impact conclusions (which are discussed below) for Alternatives A and D remain the same, though 

there may be a slight offsetting effect to recreational fishing in the excluded blocks, as it would 

reduce any potential conflict with OCS oil- and gas-related activities but would similarly prevent the 

potential for beneficial effects from new platforms or other fish attractions in the blocks.

A proposed lease sale could affect recreational fishing by affecting fish populations or by 

affecting the socioeconomic aspects of recreational fishing. The impacts of Alternative D on fish 

populations are presented in Chapter 4.7 (Fish and Invertebrate Resources) and impacts due to 

anthropogenic sound, short-term bottom disturbances, and habitat modifications. Vessel traffic 

arising from Alternative D could cause space-use conflicts with anglers. Structure emplacement 

generally enhances recreational fishing, although this positive effect would be offset during 

decommissioning unless a structure were maintained as an artificial reef. Accidental events, such 

as oil spills, could cause fishing closures and affect the aesthetics of fishing in an area. However, 

accidental events that could arise from Alternative D would likely be negligible or minor and would be 

localized. Alternative D should also be viewed in light of overall trends in OCS platform 

decommissioning, State oil and gas activities, overall vessel traffic, hurricanes, economic factors, 

and Federal and State fisheries management strategies. The incremental impacts of Alternative D 

on recreational fisheries are expected to be negligible to minor because of the relatively small 

scale of a proposed lease sale and because the positive and negative effects would partially offset 

each other. The exact impacts would depend on the locations of activities, the species affected, the 

intensity of recreational fishing activity in the affected area, and the substitutability of any lost fishing 

access. 

4.11.2.5 Alternative E—No Action

Alternative E would prevent the beneficial to minor impacts associated with a proposed 

lease sale, as discussed above. Beneficial impacts of fish attraction to new platforms or 

decommissioned platforms turned into reefs would be avoided. Similarly, negligible to minor 

impacts, such as space-use conflicts, oil spills, or direct harm to fish populations, would be avoided. 

However, recreational fisheries would still be subject to the impacts from other ongoing activities 
4-338 Gulf of Mexico Multisale EIS

related to previous lease sales under the OCS Program, as well as the impacts from the non-OCS 

oil- and gas-related sources discussed above.

4.12 RECREATIONAL RESOURCES

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

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

recreational resources are presented in this chapter. The approach of the analysis is to focus on the 

potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., exploration, 

development, and production), as well as accidental events and cumulative impacts, and to define 

the impact-level measures for each impact-producing factor.

Impact-Level Definitions

In this chapter (and in the analyses of the alternatives) the impact measures are defined in 

terms of the intensity, duration, and geographical extent of the impacts to the human uses of 

recreational resources along the Gulf Coast. In particular, the impacts of each impact-producing 

factor are summarized in Table 4-23 using the impact-level measures below.

• Beneficial – Impacts would be beneficial.

• Negligible – Little or no detectable impact.

• Minor – Impacts are detectable but less than severe.

• Moderate – Impacts are severe but are short term and/or not extensive.

• Major – Impacts are long term, extensive, and severe.

Table 4-23. Recreational Resources Impact-Producing Factors.

Recreational Resources Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Marine Debris Negligible to Negligible to Negligible to Negligible to Negligible

Minor Minor Minor Minor

Space-Use Conflicts Negligible to Negligible to Negligible to Negligible to Negligible

Minor Minor Minor Minor

Structure Emplacement 

and Removal

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible 

Minor Minor Minor Minor

Visual Impacts Negligible to Negligible to Negligible Negligible to Negligible

Minor Minor Minor

Indirect Econoic 

Impacts

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible 

Minor Minor Minor Minor
Description of the Affected Environment and Impact Analysis 4-339

Recreational Resources Magnitude of Potential Impact

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Accidental Impacts

Oil Spills Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Cumulative Impacts

OCS Oil and Gas

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible Minor Minor Minor Minor

Non-OCS Oil and Gas

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible 

Minor Minor Minor Minor

4.12.1 Description of the Affected Environment

The GOM is home to various resources that support recreational activities. These include 

ocean-based resources as well as resources in counties and parishes along the Gulf of Mexico. The 

overall scales of recreation and tourism are discussed in the following section. The resources that 

support recreational activities are presented in subsequent sections and are organized according to 

the type of recreational resource.

Scales of Recreation and Tourism

Eastern Research Group (2014a) developed methodologies for estimating the amount of 

employment supported by recreation and tourism activities in a particular area. This entailed 

defining which industries comprise recreation and tourism, as well as estimating the percent of each 

industry that supports tourism. For example, the hotel industry is primarily supported by tourists, 

while the restaurant industry is supported by both tourists and local residents. BOEM has identified 

23 Economic Impact Areas (EIAs), which are critical to understanding how a proposed action would 

affect human resources across the Gulf of Mexico (illustrated in Figure 4-27 in Chapter 4.14). 

Table 4-24 presents data regarding the scales of direct employment and value-added in the EIAs, 

which cover the geographical extents of the impacts to recreational resources. Table 4-24 was 

derived by applying data from IMPLAN Group, LLC. (2015) to the methodologies developed in 

Eastern Research Group (2014a). As can be seen, the recreation and tourism industries are sizable 

in many areas along the Gulf Coast. The areas with the largest recreation and tourism industries are 

TX-3 (which includes Houston and Galveston), LA-6 (which includes New Orleans), and various 

EIAs along the Florida coast. Parts of coastal Mississippi and Alabama also have sizeable 

recreational economies, which are supported by parks, beaches, and casinos.
4-340 Gulf of Mexico Multisale EIS

Table 4-24. Recreational and Tourism Employment and Value-Added in BOEM's Economic Impact 

Areas in 2013. 

EIA

Recreational 

Employment

Recreational 

Value-Added

Tourism 

Employment

Tourism 

Value-Added

TX-1 68,769 2,596,402,975 19,081 1,203,931,388

TX-2 48,362 1,868,401,512 15,225 739,484,187

TX-3 366,048 15,331,216,510 123,709 8,466,549,982

TX-4 5,033 188,869,415 1,227 100,190,697

TX-5 18,829 709,291,174 4,763 395,566,972

TX-6 1,417 53,257,782 387 23,864,658

LA-1 14,399 683,645,908 6,149 293,572,508

LA-2 2,799 105,494,355 775 46,049,357

LA-3 32,869 1,315,185,525 9,639 566,173,408

LA-4 17,725 788,255,437 6,269 274,186,740

LA-5 50,188 2,028,801,718 14,122 975,127,188

LA-6 89,036 4,458,755,918 34,493 1,976,234,240

LA-7 23,637 948,326,917 6,577 379,903,898

MS-1 33,103 1,560,781,492 14,167 545,645,437

MS-2 1,475 54,100,278 391 19,098,912

AL-1 37,649 1,274,887,170 10,477 681,999,085

AL-2 3,483 120,034,728 873 73,873,691

FL-1 72,212 2,756,594,208 24,852 1,233,121,800

FL-2 31,357 1,173,072,208 10,300 445,046,333

FL-3 7,954 278,409,013 2,438 114,397,442

FL-4 67,758 2,497,491,474 18,301 1,153,527,693

FL-5 254,735 11,239,013,764 80,319 4,948,465,196

FL-6 115,642 5,472,107,011 45,683 2,263,684,576

State Totals

Texas EIAs 508,457 20,747,439,369 164,393 10,929,587,884

Louisiana EIAs 230,653 10,328,465,778 78,023 4,511,247,338

Mississippi EIAs 34,578 1,614,881,770 14,558 564,744,348

Alabama EIAs 41,132 1,394,921,898 11,349 755,872,776

Florida EIAs 549,658 23,416,687,679 181,891 10,158,243,038

All EIAs 1,364,478 57,502,396,493 450,215 26,919,695,385

EIA = Economic Impact Area.

Sources: Eastern Research Group, Inc.(2014a) and IMPLAN Group, LLC (2015).

Beaches

Beach visitation is one of the most popular activities along the Gulf Coast. The USEPA’s 

“National List of Beaches” (USEPA, 2015e) is an online tool that lists and provides information 
Description of the Affected Environment and Impact Analysis 4-341

regarding the beaches in any county or parish along the Gulf Coast. Texas and West Florida have 

the most number of beaches, although there are various beach areas in Louisiana, Mississippi, and 

Alabama. The National Survey on Recreation and the Environment estimates the following number 

of Americans age 16 and older that visit the beaches in each Gulf Coast State annually: Florida 

(21,989,300); Texas (4,929,700); Alabama (1,527,900); Mississippi (956,700); and Louisiana 

(578,500) (Betz, official communication, 2010).

Wildlife Viewing

A variety of information regarding the scales of wildlife tourism in various Gulf Coast areas is 

presented in Lowe and Stokes (2013). For example, this report finds that over 1,100 wildlife guide 

businesses support over 11,000 dining and lodging businesses. This report estimated that wildlife 

tourism along the Gulf Coast supports over $19 billion in spending and generates over $5 billion in 

Federal, State, and local tax revenues. The three primary forms of wildlife tourism are fishing (which 

supports $8 billion in spending), wildlife watching (which supports $6.5 billion in spending), and 

hunting (which supports $5 billion in spending). Wildlife tourism supports the most spending in 

Florida ($8 billion) and Texas ($5 billion); wildlife tourism supports approximately $2 billion in 

spending each in Louisiana, Mississippi, and Alabama.

Artificial Reefs

Activities such as recreational fishing and diving are supported by various artificial reef 

structures in the Gulf of Mexico. Oil and gas platforms are particularly supportive of recreational 

fishing and diving activities; more information regarding the affected environment for recreational 

fishing is presented in Chapter 4.11.1 (Recreational Fishing). The locations of oil and gas platforms 

in the GOM can be accessed on the, Energy Information Administration’s online tool that lists all 

energy infrastructure in the GOM (USDOE, Energy Information Administration, 2015f). The Gulf 

Coast States also have programs to develop artificial reef structures (including decommissioned oil 

and gas structures) to support biological diversity and recreational activities. Details regarding these 

programs, including the locations of reef sites, are described in Fikes (2013).

Marine Protected Areas 

The GOM is home to many marine protected areas that support recreational activities such 

as wildlife viewing, nature experiences, and beach visitation. The marine protected areas in the 

GOM include various Federal and State entities, such as parks, wildlife refuges, national marine 

sanctuaries, and national seashores. A map of all of the marine protected areas in the Gulf of 

Mexico can be found on the NOAA’s website (USDOC, NOAA, 2015l). Estimates of the number of 

visitors, amount of spending, number of jobs, and amount of income in 2014 supported by each 

national park along the Gulf Coast are provided in Cullinane-Thomas et al. (2015). The number of 

visitors and the amount of visitor spending supported by parks along the Gulf Coast are listed below.

• Padre Island National Seashore (Texas) (578,814 visitors; $23,892,700)
4-342 Gulf of Mexico Multisale EIS

• Jean Lafitte National Historical Park and Preserve (Louisiana) (445,524 visitors; 

$24,986,300)

• Gulf Islands National Seashore (Mississippi and Florida) (4,455,240 visitors; 

$185,611,000) (About 25 percent of these impacts occur in the Mississippi 

District.)

• De Soto National Memorial (Florida) (342,039 visitors; $19,182,600)

• Big Cypress National Preserve (Florida) (1,192,856 visitors; $91,111,200)

• Everglades National Park (Florida) (1,110,900 visitors; $104,476,500)

• Dry Tortugas National Park (Florida) (64,865 visitors; $3,783,600)

National seashores are expanses of sea coast maintained for the study of wildlife and for 

public recreational use. Additional details regarding the two national seashores in the Gulf of Mexico 

are presented below.

Gulf Islands National Seashore

The Gulf Islands National Seashore consists of two mainland portions and four barrier island 

portions in the northwest Florida panhandle, and a mainland section and six barrier islands in 

Mississippi (Figure 4-24). The Gulf Islands National Seashore was established by Congress in 

1971 to preserve the outstanding natural and recreational values of these areas. In particular, these 

areas are used for diverse recreational activities such as swimming, camping, wildlife-watching, and 

wilderness experiencing. In 1978, Horn and Petit Bois Island were designated as having wilderness 

status. This status reflects the pristine and undeveloped nature of these islands. The Final General 

Management Plan of the Gulf Islands National Seashore provides detailed information regarding the 

recreational opportunities in various locations (USDOI, NPS, 2014a).

Padre Island National Seashore

The Padre Island National Seashore consists of a portion of Padre Island along the southern 

Gulf Coast of Texas. The Padre Island National Seashore was established in 1962 to protect the 

largest stretch of undeveloped barrier island in the world. The Padre Island National Seashore 

offers excellent opportunities for beach visitation, swimming, fishing, birdwatching, and windsurfing. 

More information regarding the recreational opportunities at the Padre Island National Seashore is 

provided in Beach Vehicle Environmental Assessment for Padre Island (USDOI, NPS, 2011b).
Description of the Affected Environment and Impact Analysis 4-343

Figure 4-24. Gulf Islands National Seashore.

4.12.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

recreational resources that would arise from projected activities from a proposed action are analyzed 

in this chapter. While there are some differences in the amount of activities associated with the 

alternatives, many of the impacts associated with the alternatives are similar. Therefore, this 

chapter describes the impacts that are expected to apply to all alternatives, while any deviations 

from these impact conclusions are discussed in Chapters 4.12.2.1-4.12.2.5. 

Routine Activities

The following routine OCS oil-and gas-related activities associated with a proposed action 

would potentially affect recreational resources: marine trash and debris (Chapter 3.1.5.3.4), vessel 

traffic (Chapter 3.1.4.4), platforms serving as artificial reefs (Chapter 3.1.6.2), visibility of OCS 

platforms (Chapter 3.1.3.4.3), and economic factors.

Accidental discharges of marine debris from OCS oil- and gas-related vessels and facilities 

could reach beaches and other coastal resources, which could affect the aesthetics of these areas. 

The discharge of marine debris is subject to a number of laws and treaties. These include the 
4-344 Gulf of Mexico Multisale EIS

Marine Debris Research, Prevention, and Reduction Act; the Marine Plastic Pollution Research and 

Control Act; and the MARPOL-Annex V Treaty. Regulation and enforcement of these laws is 

conducted by a number of agencies such as the U.S. Environmental Protection Agency, NOAA, and 

the U.S. Coast Guard. The BSEE provides information on marine debris and awareness and 

requires training of all OCS personnel through the “Marine Trash and Debris Awareness and 

Elimination” NTL (NTL 2015-BSEE-G03). This NTL instructs OCS operators to post informational 

placards on production facilities and drilling rigs that outline the legal consequences and potential 

ecological harms of discharging marine debris. This NTL also states that OCS workers should 

complete annual marine debris prevention training; operators are also instructed to develop a 

certification process for the completion of this training by their workers. Compliance with this NTL 

would become mandatory if the Protected Species Stipulation were applied. These various laws, 

regulations, and NTL would likely lead the potential damage to recreational resources from the 

discharge of marine debris from OCS operations to be negligible to minor. 

The OCS vessel traffic can also affect the aesthetics of recreational experiences in certain 

areas. The OCS vessel traffic can also cause space-use conflicts with recreational vessels. 

However, OCS vessels move between onshore support bases (which are typically not near 

recreational areas) and production areas far offshore, meaning any potential impact would likely be 

temporary. In addition, a proposed action would add only a small amount of vessel traffic. 

Chapters 3.1.7 and 4.14.1.1.1 provide more information regarding OCS vessel traffic. Therefore, 

impacts from space-use conflicts would likely be negligible to minor.

The OCS platforms serve as artificial reefs and, thus, often have positive impacts on 

recreational fishing and diving (Hiett and Milon, 2002). The extent to which a particular platform 

supports recreational activities would depend on numerous factors, such as its distance from shore, 

the fish populations it supports, and the aesthetics of an area (Ditton et al., 2002). The positive 

effects of platforms would be reversed at decommissioning unless a platform is maintained as an 

artificial reef through a Rigs-to-Reefs program. Details regarding these programs, including the 

locations of reef sites, are described in Fikes (2013).

The visibility of OCS platforms can also affect the aesthetics of certain recreational areas. 

These impacts depend on the type of recreational area and on the extent to which platforms are 

visible. For example, OCS platforms could detract from the nature experiences in certain Gulf Coast 

parks. The size and location of an offshore structure depends on the reservoir being tapped, 

characteristics of the well-stream fluid, and the type of processing needed to treat the hydrocarbons. 

The extent to which a platform is visible depends on various factors, such its distance, elevation, 

size, weather conditions, air pollution, and lighting (Bounds, 2012). Federal OCS waters are 9 nmi 

(10.36 mi; 16.67 km) from the Texas shore, and only under good weather conditions would a 

platform be visible to a person standing at the shoreline or to a person in a multi-story building. 

Federal OCS waters are 3 nmi (3.5 mi; 5.6 km) from Louisiana, Mississippi, and Alabama. In a 

study conducted by the Geological Survey of Alabama (1998), several facets of the visibility of 

offshore structures were analyzed. This study found that visibility is dictated not only by size and 

location of the structures and curvature of the Earth but also by atmospheric conditions. Social 
Description of the Affected Environment and Impact Analysis 4-345

scientists added factors, such as the viewer’s elevation (ground level, in a 2-story house, or in a 

30-story condominium) and the viewer’s expectations and perceptions.

During scoping for recent EISs, the NPS raised questions regarding the potential visual 

impacts from OCS platforms to Horn and Petit Bois Islands. Horn and Petit Bois Islands are 

federally designated wilderness areas and are sensitive to disruptions to nature experiences. Cole 

(2012) is a literature review of various types of wilderness experiences. For example, the NPS is 

concerned regarding the impacts from OCS platforms on the sky-viewing experiences on these 

islands, particularly at night. The NPS provided BOEM with baseline data regarding the overall 

scales of natural and anthropogenic light at Horn and Petit Bois Islands (USDOI, NPS, 2014a). This 

data found that the anthropogenic light ratio is 537 percent higher than baseline conditions at Horn 

Island and 510 percent higher than baseline conditions at Petit Bois Island. However, these data do 

not distinguish between OCS oil and gas and non-OCS light sources. The U.S. Dept. of Homeland 

Security, Coast Guard (2008) provides more information regarding the lighting requirements for OCS 

structures, such as the number and orientation of lights, to ensure maritime safety.

Historical experiences offer some insights into the potential visual impacts of platforms near 

Horn and Petit Bois Islands. Bounds (2012) offers evidence that oil and gas development near 

Dauphin Island (Alabama) caused negative impacts to tourism. The visibility of oil and gas 

structures near Texas and Louisiana appear to have more limited (and in some cases positive) 

impacts (USDOI, NPS, 2001; Nassaur and Benner, 1984), although the visual impacts of platforms 

arising from a proposed action would be subjective depending on the location and people in 

question. For example, platform lighting can detract from some nature experiences but it can also 

improve visibility and add contrast to the landscape. However, the most relevant historical analogy 

is that of offshore development near Mississippi. Figure 4-25 presents information regarding the 

current and historical locations of structures in the vicinity of Horn and Petit Bois Islands. The OCS 

structures have existed close to Petit Bois Island. Most of these have been removed; a few 

structures remain 7-10 mi (11-16 km) away. No studies have analyzed the impacts of the historical 

OCS structures on visitor experiences. Figure 4-26 is a photograph of the remaining OCS 

structures taken from Petit Bois Island. Figure 4-26 also shows a ship passing through the major 

shipping fairway near Petit Bois Island; the location of this shipping fairway is shown in Figure 4-25. 

This shipping fairway would continue to be used regardless of a proposed action. In Figure 4-26, 

the platforms are barely visible and have less of an impact on the viewshed than the passing ship.
4-346 Gulf of Mexico Multisale EIS

Figure 4-25. Historical Structure Locations near Horn and Petit Bois Islands.

Figure 4-26. Photograph of Remaining OCS Structures taken from Petit Bois Island 

Looking South (modified and reprinted with permission from Bob 

Marsh, [official communication, 2016]). (Petit Bois Island is within the 

Gulf Islands National Seashore and is a National Park Servicedesignated wilderness area.)
Description of the Affected Environment and Impact Analysis 4-347

An analysis of the visual impacts of a proposed action depends importantly on the locations 

of the structures likely to arise. Less than 1 percent of the total oil and gas reserves in the GOM 

Federal OCS are estimated to exists offshore Mississippi (USDOI, BOEM, 2013b). This makes it 

unlikely that a production platform would arise near Horn and Petit Bois Islands in the foreseeable 

future, particularly given the low current energy prices. In particular, the remaining energy resources 

offshore Mississippi are likely natural gas (USDOI, BOEM, 2013b). The Henry Hub spot price for 

natural gas has fallen from an annual average of $8.86/MMBtu (million British thermal units) in 2008 

to a monthly average of $2.84/MMBtu in July 2015, in part due to the development of U.S. onshore 

natural gas resources (USDOE, Energy Information Administration, 2015g). Therefore, even if there 

were a lease near Horn or Petit Bois Island, it would probably be developed using minimal structures 

that tie back to existing platforms due to cost considerations. In addition, BOEM developed the 

Information to Lessees and Operators (ITL) that provides for NPS consultation on a lessee’s plans 

(excerpt from past ITL below), as appropriate, and began adding the ITL to the Notices of Sale for 

proposed CPA lease sales beginning with CPA Lease Sale 231. The lease blocks that have 

previously been included the Gulf Islands National Seashore ITL are illustrated in Figure 2-6. 

BOEM would expect this ITL to be applied to any future GOM lease sales encompassing all or a 

portion of the CPA. For these reasons, potential impacts to these islands would likely be negligible

to minor. 

(q) Gulf Islands National Seashore. Potential bidders are hereby notified that 

postlease plans submitted by lessees of whole and partial lease blocks located within 

the first 12 miles of Federal waters near the Gulf Islands National Seashore (State of 

Mississippi Barrier Island Chain Map, enclosed with ITL) may be subject to additional 

review in order to minimize visual impacts from development operations on these 

blocks. BOEM will review and make decisions on a lessee’s plans for these blocks in 

accordance with applicable Federal law and regulations, and BOEM policies, to 

determine if visual impacts are expected to cause serious harm and if any additional 

mitigative action is required. Mitigations may include, but are not limited to, 

requested changes in location, modifications to design or direction of proposed 

structures, pursuing joint use of existing structures on neighboring blocks, changes in 

color design, or other plan modifications. BOEM may consult with the State of 

Mississippi and/or the State of Alabama and with the National Park Service, 

Southeast Regional Office, during such reviews as appropriate.

The following whole and partial blocks, are specifically identified for this ITL: 

Chandeleur Area – 1; Mobile – 765-767, 778, 779, 809-823, 853-867, 897-910, 

942-954, 987-997; and Viosca Knoll – 24-27.

The OCS oil- and gas-related activities can also affect recreational resources indirectly due 

to economic factors. First, increased coastal infrastructure necessary to support offshore activities 

can create space-use conflicts. However, even if a space-use conflict was to arise in a particular 

instance, it is likely that a number of substitute recreational sites would be available. The OCS oiland gas-related activities also have the potential to increase or decrease the demand for 
4-348 Gulf of Mexico Multisale EIS

recreational resources in certain communities. Increased demand for recreational resources has the 

potential to attract new recreational firms to a community; however, increased demand also has the 

potential to lessen the enjoyment of a particular resource by some community members. The OCS 

structures could also affect property values in nearby areas. However, as discussed in Chapter 

3.1.2.1, the existing oil and gas infrastructure would likely be sufficient to handle the amount of 

activity associated with a proposed action. Thus, there would likely be no noticeable increase in 

such impacts. In addition, there is sufficient land in the analysis area to handle any new 

development. Therefore, these indirect economic impacts would likely be negligible to minor. 

Accidental Events

Accidental events, such as oil spills and the subsequent response activity, could affect 

various recreational resources. The impacts of drilling fluid spills and chemical spills on recreational 

resources are expected to be negligible because of their small sizes and far distances from 

recreational resources and are thus not discussed in detail. An oil spill that remained offshore could 

cause closures that may affect recreational fishing, diving, and boating. An offshore oil spill could 

also impact nearby coastal areas through media coverage or through misperceptions and 

uncertainty regarding the extent of the spill. An oil spill would have more direct impacts if it were to 

reach coastal areas. 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 difficulty of removing oil from these areas. 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. 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, 2015m). The 

ESI maps also provide point indicators for recreational resources.

The effects of an oil spill on a region would depend on the size of the spill, as well as the 

success of the containment and cleanup operations following an oil spill. Both manual and machinebased techniques can be used to clean oil; the cleaning technique chosen for a particular beach 

would depend on the nature of the oiling of a particular beach area. The nature of cleanup 

operations would also depend on whether a particular beach serves as a habitat to particular animal 

species because removing oil deep below a beach surface can sometimes do more ecological harm 

than good. As a result, ecological beaches are often only cleaned to a shallow depth, while 

nonecological (“amenity”) beaches are often cleaned more extensively. The cleanup plan for any 

particular beach is determined by a Shoreline Treatment Recommendation, which is prepared by the 

relevant State and Federal agencies for a particular spill. An example of a Shoreline Treatment 

Recommendation following the Deepwater Horizon explosion and oil spill for Grande Isle, Louisiana, 

can be found at RestoreTheGulf.gov (2010).

Recreational resources such as beaches serve as important bases for certain local 

economies. Therefore, oiled beach regions can cause economic losses to both individuals and firms 

in the area of an oiled or closed beach. An economic analysis of the costs of hypothetical beach 
Description of the Affected Environment and Impact Analysis 4-349

closures along the Texas Gulf Coast was performed by Parsons and Kang (2007). They estimate 

that the economic costs of beach closures along the Padre Island National Seashore would range 

from $26,000 to $172,000 per day, depending on the time of year at which the closures would occur. 

The New Orleans oil spill of 2008 demonstrates that a spill can affect different types of recreational 

activities. Namely, this spill impacted some of the boating and restaurant businesses in its vicinity; it 

also caused some aesthetic impacts to the experiences of tourists in the region (Tuler et al., 2010).

Eastern Research Group (2014b) prepared a study of the impacts of the Deepwater Horizon

oil spill on tourism activities in the Gulf region. Eastern Research Group 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 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 hold up better in the spill’s aftermath. Also, tourism generally rebounded strongly after the initial 

decline. Indeed, employment held up well in most counties and parishes following the Deepwater 

Horizon explosion, oil spill, and response, which supported the recovery. Finally, the impacts of the 

spill on tourism were shaped by the damage payment system, cleanup processes, and lessons 

learned from prior disasters. However, an oil spill along the lines of the Deepwater Horizon oil spill is 

not reasonably foreseeable and is not considered as part of a proposed action. The impacts of a 

catastrophic oil spill are analyzed in the Catastrophic Spill Events Analysis white paper (USDOI, 

BOEM, 2016c).

Any oil spills arising from a proposed action are likely to be small and localized, and thus, the 

corresponding impacts would be less than those experienced after the Deepwater Horizon

explosion, oil spill, and response. In addition, there would likely be response and mitigation efforts 

subsequent to an oil spill. Finally, there would likely be numerous alternative recreational sites 

during the duration of an oil spill of the type and size that may be reasonably foreseeable as a result 

of a proposed lease sale. Therefore, the impacts of an oil spill on recreational resources are 

expected to be negligible to minor. 

Cumulative Impacts

The cumulative analysis considers the incremental impacts of a proposed action relative to 

past, present, and future OCS lease sales. The following cumulative OCS oil-and gas-related 

activities would potentially affect recreational resources: marine trash and debris, visibility of OCS 

platforms, space use conflicts, OCS related spills, and infrastructure emplacement and removal. 

This analysis also considers the incremental impacts of a proposed action relative to non-OCS oiland gas-related sources such as aesthetic impacts, beach/wetland erosion, beach disruptions, 

space-use conflicts, and economic factors.
4-350 Gulf of Mexico Multisale EIS

OCS Oil- and Gas-Related Impacts

Aesthetic Impacts 

A proposed action would contribute to aesthetic impacts of the existing and future OCS 

Programs. For example, the OCS Program contributes to the marine debris problems along the Gulf 

Coast. The BSEE provides information on marine debris and awareness and requires training of all 

OCS personnel through the “Marine Trash and Debris Awareness and Elimination” NTL (NTL 

2015-BSEE-G03); this NTL is discussed above. Compliance with this NTL, particularly if the 

Protected Species Stipulation is applied, and other regulations as outlined in the “Routine Activities” 

section above would likely reduce the potential damage to recreational resources from the discharge 

of marine debris from OCS oil- and gas-related activities to be negligible to minor. 

A proposed lease sale would also add to the visual impacts from the OCS Program. These 

impacts would depend on the type of recreational area and on the extent to which platforms are 

visible. For example, OCS platforms could detract from the nature experiences in certain Gulf Coast 

parks. As discussed above, during scoping for recent EISs, the National Park Service raised 

questions regarding the potential visual impacts from OCS platforms to Horn and Petit Bois Islands. 

Figure 4-25 presents information regarding the current and historical locations of structures in the 

vicinity of Horn and Petit Bois Islands. The OCS structures have existed close to Petit Bois Island 

for approximately 30 years. Most of these have been removed; a few structures remain 7-10 mi 

(11-16 km) away. Figure 4-26 is a photograph of the remaining OCS structures taken from Petit 

Bois Island, in which these structures are minimally visible. The impacts of any new structure would 

likely be limited unless it was closer to Petit Bois Island than the existing structures. However, as 

discussed previously, it is highly unlikely that such a structure would arise from a proposed action 

because of economic considerations and the Bureau of Ocean Energy Management’s ITL regarding 

this issue. Any potential impacts to the Gulf Islands National Seashore would be mitigated by the 

ITL, and therefore, the incremental contribution would be negligible to minor. The incremental 

contribution to impacts to other recreational resources would also range from negligible to minor

because of the limited amount of activity and the distances of the activities from recreational areas.

Space-Use Conflicts

A proposed action would also contribute to space-use conflicts between recreational 

activities and the broader OCS Program. Bernhardt et al. (2006) present an analysis of space-use 

conflicts for oil and gas activities off the coast of Texas, although the issues they raise are generally 

applicable to OCS oil- and gas-related activities. They use a GIS-based framework to identify 

specific locations where conflicts between oil activities and other concerns (including recreational 

use) are most acute; they find that recreational use conflicts tend to be concentrated around some of 

the major wildlife viewing and beach areas near the larger population areas in Texas. There would 

also be the potential for space-use conflicts, e.g., near ports, along coastal Louisiana due to the high 

concentration of the OCS oil and gas industry in this area. The vessel traffic near these facilities 

could cause space-use conflicts with boating and recreational fishing activities. However, even if a 

space-use conflict was to arise in a particular instance, it is likely that a number of substitute 
Description of the Affected Environment and Impact Analysis 4-351

recreational sites would be available. In addition, given the entrenched nature of the OCS oil and 

gas industry along the WPA and CPA, it is unlikely that any particular OCS oil- and gas-related 

activity would significantly add to space-use conflicts. As any of the alternatives would propose 

leasing only a very small portion of the EPA, such space-use conflicts are even less likely in the 

EPA.

Oil Spills

A proposed action would contribute incrementally to the likelihood of an oil spill caused by 

the broader OCS Program. Accidental spills most likely would be small, of short duration, and not 

likely to impact Gulf Coast recreational resources. In particular, as shown in Table 3-17, most spills 

would range from 0 to 500 bbl. Should an oil spill occur and contact a beach area or other 

recreational resource, it would cause some disruption during the impact and cleanup phases of the 

spill. However, these impacts are expected to be negligible to minor because any oil spill arising 

from a proposed action is expected to be small.

Infrastructure Emplacement and Removal 

The overall OCS Program can contribute to coastal erosion through activities such as 

channel dredging and pipeline emplacements. A more detailed discussion of the cumulative impacts 

of OCS oil- and gas-related activities on coastal beaches and dunes is presented in Chapter 4.3.2. 

Further information on the cumulative impacts of OCS oil- and gas-related activities on estuarine 

ecosystems can be found in Chapter 4.3.1. Platform emplacements can encourage some 

recreational activities, such as fishing and diving. However, decommissioning of these structures 

can have negative impacts on recreational diving if a particular platform were a popular diving site. 

Hiett and Milon (2002) provide survey data that suggest that the majority of recreational diving in the 

Gulf of Mexico occurs near oil and gas structures. More information regarding the impacts of 

infrastructure emplacement and removal is presented above and can be found in Chapter 4.11. 

A single lease sale would be relatively small when compared with all past, present, and 

future lease sales (refer to Table 3-23). Therefore, the incremental cumulative impacts of the 

proposed action relative to the overall OCS Program would range from beneficial to minor. 

Non-OCS Oil- and Gas-Related Impacts

Aesthetic Impacts

Marine debris can detract from the aesthetic values of coastal areas, particularly beaches. 

Non-OCS oil- and gas-related marine debris can originate from State oil and gas activities, sewage 

treatment plants, recreational and commercial fishing, industrial manufacturing, cruise ships, and 

various forms of vessel traffic. Various government agencies participate in a coordinated effort to 

combat marine debris; a broad summary of the issues involved and the policy structure with respect 

to marine debris can be found in the Interagency Marine Debris Coordinating Committee’s report 

(USDOC, NOAA, 2008b). Ocean Conservancy (2007) describes the structure of the National Marine 

Debris Monitoring Program; Ocean Conservancy (2014) is the most recent marine debris monitoring 
4-352 Gulf of Mexico Multisale EIS

report. The incremental impacts of a proposed action are expected to be negligible to minor

because the amount of marine debris that would arise from OCS oil- and gas-related activities would

be small relative to the amount of marine debris arising from the sources mentioned above.

Aesthetic impacts can also arise from State oil and gas activities. For example, State oil and 

gas activities occur closer to shore and, thus, would cause more noise and visual impacts than OCS 

oil- and gas-related activities. In 2014, Mississippi’s plans to hold an offshore oil and gas lease sale 

in State waters were suspended when a judge ruled against Mississippi’s determination that such 

leases were purely administrative actions (NOLA.com, 2014). It is unclear how this issue would

evolve. The visual impacts to Horn and Petit Bois Islands would also be influenced by the major 

shipping fairway between the islands. This shipping artery (which is shown in Figure 4-25) leads to 

the Port of Pascagoula, which is the 21st most active port in the United States (U.S. Dept. of the 

Army, COE, 2015c). A proposed action should also be viewed in light of the overall levels of noise 

on Horn and Petit Bois Islands. White (2014) provides data on baseline noise levels at Horn and 

Petit Bois Islands relative to Fort Pickens (which is a nonwilderness, higher human use area) in the 

Florida District of the Gulf Islands National Seashore. This study found that Horn and Petit Bois 

Islands have lower overall levels of extrinsic noise than Fort Pickens. Horn and Petit Bois Islands 

have higher measures of watercraft noise and lower levels of aircraft noise than Fort Pickens.

Beach/Wetland Erosion

The OCS Program occurs in an environment in which beach and wetland resources are 

undergoing depletion due to human development, hurricanes, and natural processes. The ongoing 

risk of hurricanes is a particular coastal erosion threat in the Gulf of Mexico; coastal erosion also 

lessens protection against future hurricanes. Non-OCS-related oil spills also have the potential to 

contribute to beach erosion, both due to contaminated sediment and the potential sediment losses 

during the cleanup process. More information regarding these issues can be found in Chapter 

3.2.12. Coastal erosion trends would have impacts on recreational resources to the extent that parts 

of these areas are used for recreational activities, such as beach visitation, recreational fishing, and 

boating.

Beach Disruptions

The recreational value of beaches can be affected by beach disruptions. For example, red 

tides, which are caused by growth of microscopic algae, can negatively impact the aesthetic value of 

beaches. Red tides can also cause respiratory problems and skin irritation for beachgoers (State of 

Texas, Dept. of State Health Services, 2015). As discussed in Chapter 4.3.2 Coastal Barrier 

Beaches and Associated Dunes, beaches can also be affected by changes in water and sediment 

flow. The recreational value of beaches can also be negatively impacted by degradations of air 

quality and water quality (Chapters 4.1 and 4.2).
Description of the Affected Environment and Impact Analysis 4-353

Space-Use Conflicts

Space-use conflicts with recreational activities may arise from commercial and military traffic. 

Chapter 3.3.2.7.1 describes the military activities in the vicinity of a proposed action. For example, 

Chapter 3.3.2.7.1 discusses the military warning areas and Eglin water test areas, as well as the 

Military Areas Stipulation that applies to GOM leases. Chapter 4.14.1.4 describes the cumulative 

impacts of vessel traffic, including the ports that support the highest vessel traffic. These activities 

could disrupt recreational fishing, diving, and boating.

Economic Factors

The recreational resources along the Gulf Coast would be subject to various impacts arising 

from economic development. For example, there may be pressures to develop other industries into 

existing parks and natural resources. However, development may also encourage the expansion of 

other recreational resources, such as hotels and restaurants, to accommodate increased tourism 

and/or local recreation. The projected path of the economies along the Gulf Coast would be 

influenced by national economic trends. Recreational and tourism activity is positively correlated to 

the state of the overall national economy because higher levels of disposable income encourage 

consumers to dedicate more money to travel and leisure activities. More information regarding 

economic factors can be found in Chapter 4.14.2. 

A proposed action would be relatively small when compared with the non-OCS oil- and gasrelated factors discussed above (refer to Chapter 3). Therefore, the incremental cumulative impacts 

of a proposed action relative to these non-OCS oil- and gas-related factors would range from 

beneficial to minor. 

Incomplete or Unavailable Information

There is some incomplete or unavailable information regarding the visual impacts from a 

proposed action. In particular, the attitudes of people towards the visibility of structures that could 

arise in certain areas are not fully known. BOEM has determined that such information is not 

essential to a reasoned choice among alternatives because much of this uncertainty relates to the 

inherent uncertainty regarding where (and what types) of structures would arise from a proposed

action. In addition, existing information allows for sufficient estimates of the overall dependence of 

visual impacts to factors such as distance, height, brightness, and general location. BOEM used 

generally accepted scientific principles to estimate the visual impacts of a proposed action, including 

literature sources, data sources, and photographic evidence. This evidence suggests that the 

incremental visual impacts of a proposed action would be negligible to minor. In addition, BOEM 

has issued an ITL to ensure that visual impacts near the Gulf Islands National Seashore are 

considered at BOEM’s site-specific review stage.

4.12.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

The impacts of a proposed action would correspond to the impacts described in Chapter 

4.12.2. In particular, a proposed action would contribute to the negative aesthetic impacts and the 
4-354 Gulf of Mexico Multisale EIS

space-use conflicts that arise due to the broader OCS Program. Structure emplacements can have 

positive impacts on recreational fishing and diving because platforms often act as artificial reefs, 

although decommissioning would offset these impacts. Oil spills can negatively impact beaches and 

other coastal recreational resources. The impacts resulting from the routine activities and accidental 

events would range from beneficial to minor. A proposed action should also be viewed in light of 

economic trends, as well as various non-OCS oil- and gas-related factors than can cause space-use 

conflicts and aesthetic impacts, such as commercial and military activities. The incremental 

cumulative impacts of Alternative A relative to the impacts of all other OCS oil- and gas-related and 

non-OCS oil- and gas-related factors would be beneficial to minor. 

4.12.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative B. There would be some 

differences in impacts between Alternatives A and B due to the scales of OCS oil- and gas-related 

activities (described in Chapter 4.12.1) and to the geographic distributions of activities. Namely, 

Alternative B would prevent most impacts to recreational resources near drilling and production 

activities in Federal waters off Texas. However, since CPA/EPA activities may still be serviced by 

vessels departing from Texas ports, there could still be some space-use conflicts or impacts from oil 

spills near Texas. However, the differences between Alternatives A and B are not large enough to 

change the broad impact measures. In particular, Alternative B would contribute to the negative 

aesthetic impacts and the space-use conflicts that arise due to the broader OCS Program. Structure 

emplacements can have positive impacts on recreational fishing and diving because platforms often 

act as artificial reefs, although decommissioning would offset these impacts. Oil spills can negatively

impact beaches and other coastal recreational resources. Alternative B should also be viewed in 

light of economic trends, as well as various non-OCS oil- and gas-related factors than can cause 

space-use conflicts and aesthetic impacts such as commercial and military activities. The 

incremental cumulative impacts of Alternative B relative to the impacts of all other OCS oil- and gasrelated and non-OCS oil- and gas-related factors would be beneficial to minor. 

4.12.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Alternative C entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative C. There would be some 

differences in impacts between Alternatives A and C due to the scales of OCS oil- and gas-related 

activities (described in Chapter 4.12.1) and to the geographic distributions of activities. Namely, 

Alternative C would prevent most impacts to recreational resources near drilling and production 

activities in CPA/EPA Federal waters. However, since activities in the WPA may still be serviced by 

vessels departing from ports adjacent to the CPA/EPA, there could still be some space-use conflicts 

or impacts from oil spills near all Gulf Coast States. However, the differences between Alternatives 

A and C are not large enough to change most of the broad impact measures. The only difference is 

that the visual impacts due to structure emplacements should be negligible because all structures 
Description of the Affected Environment and Impact Analysis 4-355

would be at least 9 nmi (10.36 mi; 16.67 km) from shore and because there would be fewer structure 

installations in the WPA than in the CPA. Alternative C would contribute to the negative aesthetic 

impacts and the space-use conflicts that arise due to the broader OCS Program. Structure 

emplacements can have positive impacts on recreational fishing and diving because platforms often 

act as artificial reefs, although decommissioning would offset these impacts. Oil spills can negatively 

impact beaches and other coastal recreational resources. Alternative C should also be viewed in 

light of economic trends, as well as various non-OCS oil- and gas-related factors than can cause 

space-use conflicts and aesthetic impacts such as commercial and military activities. The 

incremental cumulative impacts of Alternative C relative to the impacts of all other OCS oil- and gasrelated and non-OCS oil- and gas-related factors would be beneficial to minor. 

4.12.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D entails leasing a subset of the area considered in Alternative A, B, or C. 

Therefore, the analysis of Alternative A, B, or C covers the potential impacts of Alternative D. The 

areas that would be restricted from leasing under Alternative D would generally be far from shore 

and comprise a small portion of recreational activities along the Gulf Coast. In addition, there would 

be some offsetting adverse impacts (due to aesthetics, space-use conflicts, and oil spills) and some 

beneficial impacts (due to structure emplacements). The exclusion of blocks south of Baldwin 

County would prevent some potential negative impacts to tourism arising from the visibility of OCS 

oil- and gas-related infrastructure; it would also prevent the space-use conflicts, aesthetic impacts, 

and impacts from accidental events described above. However, the exclusion of these blocks would 

not prevent similar impacts in other GOM areas. Therefore, the overall impact conclusions for 

Alternative D are the same as those concluded under Alternative A, B, or C, as appropriate. The 

significance of impact-producing factors on recreational resources could be somewhat less for 

Alternative D than for Alternative A, B or C, as a few additional blocks and associated activities 

would be removed from the proposed lease sale area. However, this is a very small incremental 

change compared with the other action alternatives.

4.12.2.5 Alternative E—No Action

Under Alternative E, the beneficial to minor impacts discussed above would not occur as a 

result of a proposed lease sale. However, recreational resources would still be subject to the 

impacts from the OCS Program, as well as the impacts from the non-OCS oil- and gas-related 

sources discussed above. In the short term, there would be a reduction of exploration and drilling 

activities, and there would be fewer impacts from the space-use conflicts, oil spills, and aesthetics of 

such activities. If lease sales were not held for a lengthy period of time, there may be a long-term 

reduction in impacts arising from production activities (such as the role of platforms as artificial reefs) 

as mature leases reach the end of their production period and are decommissioned.
4-356 Gulf of Mexico Multisale EIS

The magnitude of impact to an 

archaeological site is 

predicated on the assumption 

that an impact may occur from 

an offshore activity regardless 

of assigned mitigation. BOEM 

does not differentiate between 

archaeological site types 

when conducting an impact 

analysis at the programmatic 

level.

4.13 ARCHAEOLOGICAL RESOURCES

Archaeological resources are any material remains of 

human life or activities that are at least 50 years of age and that 

are capable of providing scientific or humanistic understanding 

of past human behavior, cultural adaptation, and related topics 

through the application of scientific or scholarly techniques, such 

as controlled observation, contextual measurement, controlled 

collection, analysis, interpretation, and explanation (30 CFR § 

250.105). The full analyses of the potential impacts of routine 

activities and accidental events associated with a proposed 

action and a proposed action’s incremental contribution to the 

cumulative impacts are presented in the following sections. The 

approach of the analysis is to focus on the potential impactproducing factors from routine OCS oil- and gas-related activities 

(i.e., exploration, development, and production), as well as accidental events and cumulative 

impacts (Table 4-26). A brief summary of potential impacts follows. Archaeological resources are 

primarily impacted by any activity that directly disturbs or has the potential to disturb the seafloor. 

For the OCS Program, this includes the placement of drilling rigs and production systems on the 

seafloor; pile driving associated with platform emplacement; pipeline placement and installation; the 

use of seismic receiver nodes and cables; the dredging of new channels, as well as maintenance 

dredging of existing channels; anchoring activities; post-decommissioning activities including 

trawling clearance; and the masking of archaeological resources from industry-related infrastructure 

and debris. Visual impacts to coastal archaeological and historic sites are not considered, as 

offshore oil and gas infrastructure has existed on the OCS in the CPA and WPA since the 1940s and 

constitutes a seaward historic viewshed in its own right. Additionally, its presence predates the 

NHPA, and therefore, any coastal archaeological site currently on the National Register of Historic 

Places would not derive its eligibility from an unobstructed view of the GOM.

Impact-Level Definitions

The definition of impact thresholds used in this analysis are listed below.

• Negligible – The lowest level of detection that would have neither adverse nor 

beneficial impacts.

• Minor – Disturbance of archaeological resources would result in little, if any, loss 

of site integrity.

• Moderate – Site disturbance would result in a loss of integrity and a partial loss 

of the character-defining features and information potential that form the basis of 

the site’s National Register of Historic Places’ eligibility. Mitigation is 

accomplished by a combination of archeological data recovery and in-place 

preservation.
Description of the Affected Environment and Impact Analysis 4-357

• Major – The disturbances result in a loss of site integrity to the extent that the 

resource is no longer eligible for listing in the National Register of Historic Places. 

The site’s character-defining features and information potential are lost to the 

extent that archeological data recovery is the primary form of mitigation.

• Beneficial – An archeological site is stabilized in its current condition to maintain 

its existing level of integrity or an archeological site is preserved in accordance 

with the Secretary of the Interior’s Standards for the Treatment of Historic 

Properties. 

Duration: Short-term impacts last for the duration of construction-related activities while 

long-term impacts last beyond the proposed construction activities and are permanent. Generally, 

impacts to archeological sites are considered long-term impacts.

The impact of coastal and marine environmental degradation from OCS oil- and gas-related 

activities is expected to minimally affect cultural resources in comparison to other sources of coastal 

erosion and subsidence. Impacts of routine discharges are localized in time and space, are 

regulated by USEPA permits, and would have minimal impact. Accidental events that could impact 

archaeological resources include blowouts and oil or chemical spills and the associated cleanup 

response activities, and also the loss of debris from an MODU, platform, lay barge, etc. during 

offshore operations. A noncatastrophic oil spill (even one reasonably foreseeable as a result of a 

proposed lease sale) occurring and contacting a submerged archaeological resource is unlikely, 

given that oil released tends to rise quickly to the surface and that the average size of a spill is 

<1 bbl (refer to Chapter 3.2.1.5.3).

Archaeological surveys, where required prior to an operator beginning OCS oil- and gasrelated activities, are expected to be effective at identifying possible archaeological sites. Offshore 

oil and gas activities resulting from a proposed action could adversely impact an archaeological 

resource because of incomplete knowledge on the location of these sites in the GOM. The risk of 

contact to archaeological resources is greater in instances where archaeological survey data are 

unavailable. Such an event could result in the disturbance or destruction of important archaeological 

information. Archaeological surveys provide the necessary information to develop avoidance 

strategies that would reduce the potential for adverse impacts on archaeological resources. As part 

of the environmental reviews conducted for postlease activities, available information would be 

evaluated regarding the potential presence of archaeological resources within the proposed action 

area to determine if additional archaeological resource surveys and mitigation is warranted.

4.13.1 Description of the Affected Environment

4.13.1.1 Prehistoric

Available evidence suggests that sea level in the northern GOM was at least 90 m (295 ft), 

and possibly as much as 130 m (427 ft), lower than present sea level during the period 

20,000-17,000 years Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern Gulf 
4-358 Gulf of Mexico Multisale EIS

reached its present stand around 3,500 years B.P. (Pearson et al., 1986). During periods that the 

continental shelf was exposed above sea level, the area was open to habitation by prehistoric 

peoples.

Until the late 20th century, it was generally accepted by archaeologists that the earliest 

humans in North America were the so-called Clovis peoples, named for a lanceolate-shaped, fluted 

projectile point first found near Clovis, New Mexico. The Clovis culture was thought to have entered 

the continent by way of Beringia, a landmass connecting Asia to North America exposed during the 

Last Glacial Maximum, and along an ice-free corridor opened between the Cordilleran and 

Laurentide ice sheets around 13.5 thousand years B.P. Today, however, a growing body of 

evidence has dispelled the “Clovis First” model with discovery of several sites with indisputable preClovis dates in the eastern United States (Goodyear, 2005), Chile (Dillehay, 1989; Meltzer et al., 

1997) and central Texas (Waters et al., 2011). The Buttermilk Creek Complex identified by Waters 

et al. (2011) at the Debra L. Friedkin Site (41BL1239) is the nearest to the Gulf of Mexico region and 

is dated from ~13.2 to 15.5 thousand years B.P.

Establishing a reliable date for the entrance of Native Americans into the coastal regions of 

the GOM is complicated by the fact that archaeological deposits pre-dating 5500 B.P. lie buried 

under as much as 40 m (131 ft) of sediment or are underwater on the OCS (Rees, 2010). 

Conclusive evidence for prehistoric sites on the OCS is sparse. The McFaddin Beach Site (41JF50) 

in Jefferson County, Texas, has produced hundreds of artifacts 8,000 years old or older that have 

been redeposited from sites eroding from the now-submerged Pleistocene shoreline. Forty-three 

percent of the total sample includes artifacts diagnostic of the Middle and Late Paleoindian periods 

and include Clovis, Dalton, Scottsbluff, and San Patrice projectile points (Stright et al., 1999).

Based on the best evidence currently available, the first Americans arrived on the Gulf Coast 

around 13,500 B.P. (Rees, 2010). The sea-level curve for the northern GOM proposed by Coastal 

Environments, Inc. (CEI) suggests that sea level at 12,000 years B.P. would have been 

approximately 45-60 m (148-197 ft) below the present-day sea level (CEI, 1977 and 1982). On this 

basis, the continental shelf shoreward of the 45- to 60-m (148- to 197-ft) bathymetric contours has 

potential for prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in 

both the depth of sea level and the entry date of prehistoric man into North America, BOEM adopted 

the 60-m (197-ft) water depth as the seaward extent for prehistoric archaeological site potential in 

GOM region.

Based on their 1977 baseline study, CEI (1977) proposed that sites analogous to the types 

of sites frequented by Paleoindians can be identified on the now-submerged shelf. Geomorphic 

features that have a high potential for associated prehistoric sites include barrier islands and backbarrier embayments, river channels and associated floodplains and terraces, and salt-dome 

features. Investigations in Louisiana and Florida indicate the mound-building activity by prehistoric 

inhabitants may have occurred as early as 6,200 years B.P. (cf. Haag, 1992; Saunders et al., 1992; 

Russo, 1992). Therefore, manmade features, such as mounds, may also exist in the shallow 

inundated portions of the OCS.
Description of the Affected Environment and Impact Analysis 4-359

Regional geological mapping studies by BOEM allow interpretations of specific geomorphic 

features and assessments of archaeological potential in terms of age, type of system the 

geomorphic features belong to, and geologic processes that formed and modified them. In general, 

sites protected by sediment overburden have a high potential for preservation from the destructive 

effects of marine transgression. The same holds true for sites submerged in areas subjected to low 

wave energy and for sites on relatively steep shelves, which were inundated during periods of rapid 

rise in sea level. Although many specific areas in the GOM having potential for prehistoric site 

preservation have been identified through archaeological surveys, industry generally has chosen to 

avoid these areas rather than conduct further investigations.

Holocene sediments form a thin veneer or are absent over the majority of the continental 

shelf off western Louisiana and eastern Texas (USDOI, MMS, 1984). Many large, late Pleistocene, 

fluvial systems (e.g., the Sabine-Calcasieu River Valley) are within a few meters of the seafloor in 

this area. Farther to the south and west, a blanket of Holocene sediments overlies the Pleistocene 

horizon. Along the coast, prehistoric sites representing the Paleoindian culture period through 

European contact have been reported. The McFaddin Beach site, east of Galveston in the 

McFaddin National Wildlife Refuge, has produced late Pleistocene megafauna remains and lithics 

from all archaeological periods, including a large percentage of Paleoindian artifacts (Stright et al., 

1999). A study funded by the Minerals Management Service (MMS) (BOEM’s predecessor) to 

locate prehistoric archaeological sites in association with the buried Sabine-Calcasieu River Valley 

was completed in 1986 (CEI, 1986). Five types of relict landforms were identified and evaluated for 

archaeological potential. Coring of selected features was performed, and sedimentary analyses 

suggested the presence of at least two archaeological sites.

High-resolution geophysical surveys have produced evidence of floodplains, terracing, and 

point-bar deposits in association with relict late Pleistocene fluvial systems. Prehistoric sites 

associated with these features would have a high potential for preservation. Salt diapirs with 

bathymetric expression have also been recorded during lease-block surveys in this area. Solution 

features at the crest of these domes would have a high potential for preservation of associated 

prehistoric sites. The Salt Mine Valley site on Avery Island is a Paleoindian site associated with a 

salt-dome solution feature (CEI, 1977). The proximity of most of these relict landforms to the 

seafloor facilitates further investigation and data recovery.

4.13.1.2 Historic

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 embedded in the seafloor. Europeans are known to have 

traversed the waters of the western Gulf of Mexico as early as Captain Alonso Alvarez 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).
4-360 Gulf of Mexico Multisale EIS

The NPS and MMS (BOEM’s predecessor) contracted three studies (CEI, 1977; Garrison 

et al., 1989; Pearson et al., 2003) aimed at modeling areas in the GOM where historic shipwrecks 

are most likely to exist, though numerous shipwreck discoveries since the publication of those 

studies have empirically shown their models to be flawed due to reporting biases in the historic 

record. The 1977 study concluded that two-thirds of the total number of shipwrecks in the northern 

GOM lie within 1 mi (1.6 km) of shore and most of the remainder lies between 1 and 6 mi (1.6 and

10 km) of shore (CEI, 1977). Changes in the late 19th- and early 20th-century sailing routes 

increased the frequency of shipwrecks in the open sea in the eastern GOM to nearly double that of 

the central and western GOM (Garrison et al., 1989). The Garrison et al. study also found the 

highest observed frequency of shipwrecks occurred within areas of intense marine traffic, such as 

the approaches and entrances to seaports and the mouths of navigable rivers and straits. Based on 

the results of this study, MMS identified which OCS lease blocks would require the operator to 

submit an archaeological report with their EP, DOCD, DPP, or other permit application.

Pearson et al. (2003) benefited from the experience of almost 15 years of high-resolution, 

shallow hazard surveys in lease blocks (a typical lease block is 9 mi2 [5,760 ac]) and along pipeline 

routes. Some of these surveys (almost exclusively for pipeline routes) were conducted in deep 

water. Taking the new data into account, the 2003 study recommended including some deepwater 

areas, primarily on the approach to the Mississippi River, among those lease areas requiring 

archaeological investigation. With this in mind, MMS (BOEM’s predecessor) revised its guidelines 

for conducting archaeological surveys and added about 1,200 lease blocks in the CPA to the list of 

blocks requiring an archaeological survey and assessment. These requirements are posted on 

BOEM’s website under NTL 2005-G07 and NTL 2011-JOINT-G01. Based on additional shallow 

hazard survey data and shipwreck discoveries since 2008, an archaeological survey may be 

required as a result of site-specific NEPA analysis conducted for new bottom-disturbing activity 

associated with plans (USDOI, BOEM, 2011), pipelines, and structure-removal activities. Table 4-25

illustrates the results of the surveys and archaeological reviews in the last 6 years.

Table 4-25. Archaeological Surveys and Resources Identified, 2009-2014.

Year Blocks 

Surveyed

Identified 

Shipwreck Sites

Potential Archaeological Sites Mitigated by Avoidance

(identified through requisite industry surveys)

2009 118 11 479 magnetic anomalies and 103 sonar targets

2010 74 8 274 magnetic anomalies and 100 sonar targets

2011 120 15 577 magnetic anomalies and 171 sonar targets

2012 115 15 341 magnetic anomalies and 112 sonar targets

2013 166 6 374 magnetic anomalies and 163 sonar targets

2014 144 13 417 magnetic anomalies and 146 sonar targets

Many of the above-listed shipwrecks were not previously known to exist in these areas from 

the historic record. Recent research on historic shipping routes, moreover, suggests that the ultradeepwater area of the Gulf of Mexico, between 25o and 27.5o N. latitude, was located along the 

historic Spanish trade route, which therefore increases the probability that a historic shipwreck could 

be located in this area (Lugo-Fernandez et al., 2007). This route runs through the proposed action 
Description of the Affected Environment and Impact Analysis 4-361

area. A study to conduct archival research on these historic shipping routes was completed in 2010 

(Krivor et al., 2011) and concluded that both Spanish and French vessels were lost in the 16th, 17th, 

and 18th centuries while transiting the route between Vera Cruz, New Orleans, and Havana.

A proprietary database of shipwrecks maintained by BOEM currently lists over 1,300 named 

shipwrecks in the GOM. Many of these reported shipwrecks may be considered historic and could 

be eligible for nomination to the National Register of Historic Places. Most of these wrecks are 

known only through the historical record and, to date, have not been located on the ocean floor. 

This list should not be considered exhaustive; regular reporting of shipwrecks did not occur until late 

in the 19th century, and losses of several classes of vessels, such as small coastal fishing boats, 

were largely unreported in official records.

Submerged shipwrecks off the coasts of Texas, Louisiana, Mississippi, and Alabama are 

likely to be moderately well-preserved because of the high sediment load in the water column from 

upland drainage and wind and water erosion. Wrecks occurring within or close to the mouth of bays 

likely would have been quickly buried by transported sediment and therefore somewhat protected 

from the destructive effects of wood-eating shipworms (Teredo navalis) or storms, as has been 

observed at the site of La Belle in Matagorda Bay, Texas (Bruseth and Turner, 2005). Wrecks 

occurring in deeper water also have a moderate to high preservation potential. In the deep water, 

temperature at the seafloor is extremely cold (~4 oC; 39 oF), which slows the oxidation of ferrous 

metals. While the cold water at depth would eliminate the wood-eating shipworm Teredo navalis, it 

is clear from recent studies that other marine organisms, including chemosynthetic species, 

consume wooden shipwrecks, and that microbial organism are at work breaking down steel and iron 

hulls (Atauz et al., 2006; Church et al., 2007; Church and Warren, 2008; Ford et al., 2008). Due to 

the high levels of preservation and the decrease in impacts from anthropogenic (e.g., diving, looting, 

and fishing trawling) and meteorological (e.g., tropical storms and hurricanes) events, the potential is 

higher in deep water to discover undisturbed sites.

Hurricane activity in the Gulf of Mexico has the ability to directly impact archaeological 

resources in water depths exceeding 200 ft (61 m) (Gearhart et al., 2011; Lukens and Selberg, 

2004). Wrecks occurring as a result of an extremely violent storm are more likely to be scattered 

over a broad area. The wreckage of the 19th-century steamer New York, which was destroyed in a 

hurricane, lies in 65 ft (20 m) of water and has been documented by MMS/BOEM (Irion and 

Anuskiewicz, 1999; Gearhart et al., 2011) as scattered over the ocean floor in a swath over 1,500 ft 

(457 m) long. Shipwrecks occurring in shallow water nearer to shore are more likely to have been 

reworked and scattered by subsequent storms than those wrecks occurring at greater depths on the 

OCS.

It is almost certain that any shipwrecks in shallow water within the path of Hurricanes Katrina 

or Rita were impacted to some extent by these storms. In September 2005, the NPS conducted a 

study of sites along the Gulf Coast that were impacted by Hurricane Katrina (USDOI, NPS, 2005). 

This assessment identified three types of damage that can occur to archaeological sites: tree 

throws; storm surge, scouring, and erosion; and seabed shifting. On the OCS, the two primary types 
4-362 Gulf of Mexico Multisale EIS

of damage would be associated with storm surge and seabed shifting. In early 2007, MMS awarded 

a study to investigate the impacts that recent storm activity may have had on historic shipwrecks in 

the Gulf of Mexico. Analysis of the remote-sensing surveys and diver investigations indicates that at 

least 3 of the 10 shipwrecks examined were affected by recent storm activity and that older wooden 

wrecks that had achieved some level of equilibrium in their environment were less affected than 

more recent steel-hulled wrecks (Gearhart et al., 2011).

4.13.2 Environmental Consequences

Impacts to archeological sites occur when proposed activities result in complete or partial 

destruction of the resource and are equivalent to a loss of integrity as defined in the National Historic 

Preservation Act (NHPA) (54 U.S.C. §§ 300101 et seq.). In determining the appropriate impact 

threshold, both the extent to which the proposed activity results in a loss of integrity and the degree 

to which losses can be compensated by mitigating activities, including preservation or data recovery, 

are considered. For the purposes of this analysis, all alternatives may be assumed to have 

effectively similar potential impacts to archaeological resources. Only those resources determined 

eligible or potentially eligible for listing in the National Register of Historic Places are considered 

under the NHPA. Resources are eligible for listing in the National Register of Historic Places if they 

meet one or more eligibility criteria (for archeological sites, generally Criterion D, having the potential 

to provide information important to history or prehistory) and if they possess integrity. For purposes 

of archaeological mitigation, BOEM/BSEE considers all uninspected shipwrecks, sonar targets, and 

magnetic anomalies potentially eligible for the National Register of Historic Places.

For the analysis of impacts to archeological resources, the determination of the intensity of 

an impact is based on the foreseeable loss of integrity to known or potential resources. The analysis 

considers only the direct impacts of seafloor disturbance associated with the below-listed impactproducing factors as there should be no additional impacts upon archeological resources under any 

of the alternatives under consideration upon completion of said activities. As each archaeological 

resource is unique and exists at a specific location on the seafloor, there is a high level of variability 

in how a site may be impacted by any potential impact-producing factor. Therefore, it is impossible 

to evaluate the potential impact to an archaeological site from a proposed action at the 

programmatic level. During postlease activities, each permitted action would be assessed for sitespecific potential impacts during the permit application process.

Routine Activities

Routine impact-producing factors associated with a proposed action that could affect 

archaeological resources include (1) geotechnical testing/geophysical surveys; (2) well development 

(drilling), structure installation, and maintenance; (3) pipeline installation and maintenance; 

(4) vessel or structure anchoring; and (5) idle structure removal.
Description of the Affected Environment and Impact Analysis 4-363

Geotechnical Testing/Geophysical Surveys

Geotechnical testing includes, but is not limited to, soil boring, seafloor coring, and sediment 

grabs. The area of effect for a typical geotechnical test is approximately 1 m2 (11 ft2

); however, 

several tests are usually conducted as part of a project. The likelihood that an individual test would 

negatively impact an archaeological site in an unsurveyed area is minimal; however, the effect to an 

impacted site would be significant were it to occur. Large area geophysical surveys to resolve deep 

geological structures use either ocean bottom cables or ocean bottom nodes as acoustic receivers. 

The ocean bottom cables are deployed from a surface vessel onto the seafloor. While the cable 

itself is light and flexible, the acoustic node assembly and sound dampeners can weigh up to 

approximately 400 lb (181 kg). The “blind” method of laying down and peeling up the cable from the 

seafloor could cause the cable to snag on an unknown shipwreck, causing major adverse impacts. 

The ocean bottom nodes are either dropped from a surface vessel, with a large area of potential 

bottom contact, or they are placed by ROVs. An archaeological survey is not required in advance of 

a geophysical survey; however, identified and potential archaeological resources are noted for 

avoidance. The deployment of ocean bottom cables and ocean bottom nodes dropped from the 

surface have the potential to significantly negatively impact unidentified archaeological resources. 

The ocean bottom nodes placed by ROV have minimal potential to impact archaeological resources 

as the seafloor is visually inspected before placement and recovery. Impacts to archaeological 

resources from the geotechnical testing/geophysical survey range from negligible to major if no 

mitigation is imposed, is not followed, or a site is unidentified prior to the activity. 

Well Development (Drilling), Structure Installation, and Maintenance

In total, approximately 6,700 platforms have been installed in the GOM. For fixed-legged 

structures, depending on water depth, seafloor characteristics, and vessel availability, an anchored 

barge, moored barge, or liftboat may be used in platform installation. Wells are typically drilled in a 

new location prior to structure installation. Depending primarily on water depth and vessel 

availability, a jack-up rig or anchored or dynamically positioned MODU may be used. Several 

directional wells may be drilled from a single top-hole location. Estimates of wells to be drilled and 

platforms to be installed, by water depth, are presented in Table 3-2. Impacts to archaeological 

resources from well development, structure installation, and maintenance activities range from 

negligible to major if no mitigation is imposed, is not followed, or a site is unidentified prior to the 

activity.

Pipeline Installation and Maintenance

Pipelines in the Gulf of Mexico OCS are installed as either a part of lease-block infrastructure 

or as a right-of-way across others’ leases or unleased areas. Pipeline permits allow an operator to 

install a pipeline within a planned 200-ft (61-m) corridor. Pipelines are laid with either an anchored 

or a dynamically positioned lay barge. Pipelines installed in water depths <200 ft (61 m) and those 

deemed a hazard to navigation must be buried at least 3-16 ft (1-5 m) depending on local uses (e.g., 

fairways, anchorages, etc.), typically using a water jet. Long segments have been observed to flex 

and move across the seafloor, usually due to storm activity. A survey for all proposed pipeline 
4-364 Gulf of Mexico Multisale EIS

installation, regardless of location, has only been required since 2005. An example of an adverse 

impact to an archaeological site from a pipeline installation is the 2001 installation of an oil and gas 

pipeline that bisected and damaged what is known as the Mica Shipwreck (Atauz et al., 2006). 

Impacts to archaeological resources from pipeline installation and maintenance activities range from 

negligible to major if no mitigation is imposed, is not followed, or a site is unidentified prior to the 

activity. 

Vessel or Structure Anchoring

Anchoring associated with exploration drilling, platform and pipeline emplacement, and 

decommissioning may also physically impact archaeological resources. It is assumed that, during 

anchor emplacement, an array of 20,000-lb (9,072-kg) anchors is repositioned within the area of 

potential effect. The anchor’s chain has the potential to lie along and sweep across the seafloor. 

Impacts to archaeological resources from anchoring activities range from negligible to major if no 

mitigation is imposed, is not followed, or a site is unidentified prior to the activity.

Idle Structure Removal

As per NTL 2010-G05 (“Decommissioning Guidance for Wells and Platforms”) (idle iron 

initiative), idle and toppled oil and gas industry-related structures embedded in the seafloor, 

including single-leg caissons, multi-legged jacketed fixed platforms, floating platforms secured by 

suction pilings, and subsea well-head and manifold systems, must be decommissioned and 

removed. Depending on water depth, seafloor characteristics, and vessel availability, an anchored 

barge, moored barge, or liftboat may be used. Additionally, the site must be cleared of debris to a 

radius of 600 or 1,320 ft (183 or 402 m) depending on the structure type and use. Clearance may be 

carried out by trawling or by sonar and diving operations. As of 2013, BOEM may require, as a 

condition of approval for a decommissioning permit, an archaeological survey in advance of 

structure-removal activities when no preexisting survey of the area of potential effect exists. Impacts 

to archaeological resources from structure-removal activities range from negligible to major if no 

mitigation is imposed, is not followed, or a site is unidentified prior to the activity. 

To mitigate potential adverse impacts to archaeological resources, BOEM requires 

archaeological reconnaissance survey of all areas impacted by bottom-disturbing activities and 

avoidance or other actions, up to and including full Phase III excavation, of all potential 

archaeological resources within the identified area of potential effect of the undertaking. 

Archaeological surveys 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 BOEM’s and BSEE’s Regional Directors of the discovery of any potential 

archaeological resources.
Description of the Affected Environment and Impact Analysis 4-365

Accidental Events

Accidental impact-producing factors associated with a proposed action that could affect 

archaeological resources include accidental oil spills and loss of debris from a vessel or structure.

Accidental Oil Spills

Impacts on archaeological resources could occur as a result of an accidental oil spill. A 

major impact from an oil spill would be visual and chemical contamination of a historic coastal site, 

such as a prehistoric shell midden, historic fort, or lighthouse. Although such impacts may be 

temporary and reversible, cleaning oil from historic structures is by no means a simple or 

inexpensive process (e.g., Chin and Church, 2010). The major impacts to coastal archaeological 

sites from the Exxon Valdez spill in Alaska in 1989 were related to cleanup activities, such as the 

construction of helipads, roads, and parking lots, and to looting by cleanup crews rather than from 

the oil itself (Bittner, 1996). As a result, cultural resources were recognized as significant early in the 

response to the Deepwater Horizon oil spill, and archaeologists were embedded in Shoreline 

Cleanup and Assessment Technique (SCAT) teams and consulted with cleanup crews.

An oil spill occurring and contacting an archaeological resource is unlikely, given that oil 

released tends to rise quickly to the surface and that the average size of any spill would be small. 

Refer to the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2016c) for an analysis of 

the potential impacts of a catastrophic oil spill on coastal and submerged archaeological resources.

The impacts to archaeological sites from oil spills and associated activities have not been 

quantified. 

Loss of Debris from a Vessel or Structure

Another impact that could result from an accidental event is from the loss of debris from an 

MODU, platform, lay barge, etc. during offshore operations. Debris such as structural components 

(i.e., grating, wire, tubing, etc.), boxes, pallets, and other loose items can become dislodged during 

heavy seas or storm events and fall to the seabed. Similarly, thousands of joints of drill pipe are 

used during drilling operations, requiring regular transport out to the MODU via workboats. There is 

the potential to lose pieces of drill pipe during transfer operations or when “tripping pipe” in and out 

of the wellbore. Similar to the impacts noted under “Routine Activities” (e.g., pipeline movement and 

anchor damage), if lost drill pipe or debris were to fall onto an unknown archaeological resource, the 

resulting disturbance could destroy fragile materials, such as the hull remains and artifacts, and 

could disturb the site’s context and associated artifact assemblage. Additionally, lost material could 

result in the masking of actual archaeological resources or the introduction of false targets that could 

be mistaken in the remote-sensing geophysical record as historic resources. Impacts to 

archaeological resources from the loss of debris from a vessel or structure range from negligible to 

major. 
4-366 Gulf of Mexico Multisale EIS

Cumulative Impacts

In addition to the cumulative impacts of the OCS Program whose impacts are the same as 

described above, the cumulative scenario activities that could potentially impact archaeological 

resources include (1) oil spill and response, (2) State oil and gas programs, (3) sand extraction, 

(4) artificial reef development, (5) fairway and anchorage use and maintenance, (6) commercial 

bottom trawling (fishing), (7) treasure hunting/looting, (8) sport diving, (9) research and monitoring, 

and (10) hurricanes. The chance that a localized cumulative scenario activity could impact any 

particular archaeological resource on the OCS is negligible (archaeological resources cannot be 

considered as a population); therefore, if a cumulative scenario activity were to impact an 

archaeological resource, it would constitute the primary impact to that resource. Consequently, this 

analysis identifies the range of potential impact levels to a particular archaeological site from specific 

cumulative scenario activities if the impact were to occur.

OCS Oil- and Gas-Related Impacts

Oil Spill and Response

Oil spills in the GOM range from sub-seafloor contained production casing leaks to 

environmentally damaging well blowouts to shipping accidents. There have been seven significant 

oil spills in the GOM, including accidents in State and Mexican waters: Ixtoc (1979); Burmah Agate 

(1979); Alvenus (1984); Megaborg (1990); Ocean 255 (1993); the aggregation of the effects of 

Hurricane Katrina (2005) (USDOC, NOAA, n.d.); and Deepwater Horizon/Macondo (2010). Activities 

associated with oil spills that may affect archaeological resources include anchoring of response 

vessels, drilling relief wells, the application of chemical dispersant, and the distribution of oil. Due to 

the emergency nature of oil spills, an archaeological survey is not always feasible before related 

activities take place. The impacts to archaeological sites from oil spills and associated activities 

have not been quantified. 

Non-OCS Oil- and Gas-Related Impacts

State Oil and Gas Programs

State oil and gas program wells, structures, and pipelines in State waters are not under the 

jurisdiction of BOEM with respect to the archaeological resource protection requirements of the 

NHPA. Under the NHPA, other Federal agencies (such as the COE) that issue permits associated 

with pipelines in State waters are responsible for taking into consideration the effects of agencypermitted actions on archaeological resources. Therefore, the impacts that might occur to 

archaeological resources by pipeline construction originating from OCS oil- and gas-related activity 

within State waters should be mitigated under the requirements of the NHPA, and the same 

archaeological surveys for planned pipelines that lead into a landfall or a tie-in to a pipeline in State 

waters are required. Impacts to archaeological resources from State oil and gas program activities 

range from negligible to major if no mitigation is imposed, is not followed, or a site is unidentified 

prior to the activity. 
Description of the Affected Environment and Impact Analysis 4-367

Sand Extraction

Impacts to archaeological resources as a result of sand extraction activities include direct 

contact of a resource by the dredge head or anchors, redepositing of artifacts into the dredge 

disposal area, sediment transport and/or seabed destabilization around wrecks adjacent to the 

dredge pit, and direct contact of terrestrial or submerged resources in the dredge disposal area. The 

OCS sand resources have been identified off the coasts of Mississippi, Louisiana, and Texas in the 

following OCS areas: High Island; West Cameron; Vermilion; South Marsh Island; Eugene Island; 

Ship Shoal; South Pelto; West Delta; Chandeleur; and Main Pass. An archaeological review is 

required in advance of sand extraction activities. A current/ongoing BOEM study is quantifying the 

impacts to archaeological resources from sand extraction to incorporate into future sand extraction 

permit application review. Impacts to archaeological resources from sand extraction activities range 

from negligible to major if no mitigation is imposed, is not followed, or a site is unidentified prior to 

the activity. 

Artificial Reef Development

Artificial reef areas are designated by the COE for the disposal of decommissioned vessels, 

platform jackets, and other materials in order to promote and enhance biological systems. Potential 

impacts to archaeological resources include direct contact of the resource by the reefed material. 

Reefing areas are typically developed in <600 ft (183 m) of water; however, two fixed platform 

jackets have been reefed in place offshore Louisiana in water depths 620 and 650 ft (189 and 

198 m). Nine additional fixed platforms that range in water depths of 650-1,350 ft (198-411 m) are 

currently being considered for reefing in place by State-managed artificial reef programs (Texas, 

Louisiana, and Alabama). In addition to the State-managed programs, there are old artificial reefs 

and disposal areas that are not included in a State-managed program; these areas have not been 

quantified. The COE does not consistently require archaeological survey in advance of reef 

permitting. Most sonar and multibeam surveys by the State artificial reef programs are conducted 

after artificial reef deployments to verify placement. The area of potential effect of reefing activities 

also includes the anchor radius of tow and placement barges, which often extends outside of the 

reefing area. Impacts to archaeological resources from artificial reef development activities range 

from negligible to major if no mitigation is imposed, is not followed, or a site is unidentified prior to 

the activity. 

Fairway and Anchorage Area Use and Maintenance

Fairways and anchorage areas are established to provide safe approaches to major ports in 

the GOM. Fairways and anchorage areas regulate allowable oil and gas industry and other activities 

within them, such as installation spacing, anchor and cable depth, pipeline burial, etc. Proper aids to 

navigation must be affixed to the seafloor. Fairways may be dredged to maintain safe water depths 

for navigation. An archaeological survey may not have been required in advance of fairway and 

anchorage area designation. Impacts to archaeological resources from fairway and anchorage area 

use and maintenance range from negligible to major if no mitigation is imposed, is not followed, or 

a site is unidentified prior to the activity. 
4-368 Gulf of Mexico Multisale EIS

Commercial Bottom Trawling (Fishing)

Commercial bottom trawling may make use of nets, rakes, or dredges to harvest 

commercially important benthic organisms (e.g., shrimp, oysters, etc.). An archaeological survey 

and review has never been required in advance of the development of a commercial bottom trawling 

fishery in the GOM. Geophysical and diver inspection surveys have shown that trawling 

apparatuses have negligible to fully destructive impacts to submerged archaeological resources 

depending on the resources composition and integrity (Steinmetz, 2010). For example, a shrimp net 

may snag and remain attached to the hull of a 20th-century steel vessel, while a shellfish rake or 

dredge may obliterate a 19th-century wooden sailing vessel leaving little to no trace of it on the 

seafloor. Impacts to archaeological resources from commercial bottom trawling range from 

negligible to major. There is no archaeological mitigation applied to commercial fishing.

Treasure Hunting/Looting

Treasure hunting involves the intentional, nonscientific, usually commercial exploitation of 

archaeological resources for profit. Often, specific shipwrecks are targeted for salvage. It is 

unknown how many archaeological sites have been salvaged by treasure hunters in the GOM. Two 

recent examples of commercial treasure hunting in the Gulf of Mexico OCS are the salvage of the 

New York (Gearhart et al., 2011; Irion and Ball, 2001; Bowers, 2008) and El Cazador

(www.elcazador.com). Looting involves the planned or opportunistic removal of artifacts or features 

from an archaeological site. It may range from the collection of mobile surface artifacts to the 

complete destruction and/or removal of the vessel. An example of the looting of an archaeological 

site was the attempted collection and destruction of artifacts on the shipwreck known as the Mardi 

Gras wreck during an remotely operated vehicle pipeline inspection (Ford et al., 2008). Impacts to 

archaeological resources from commercial treasure hunting/looting range from moderate to major. 

There is no archaeological mitigation applied to treasure hunting/looting.

Sport Diving

Sport diving includes private or commercial recreational diving on archaeological sites for 

pleasure and education. Negative impacts to archaeological sites from sport diving may result from 

boat anchor and mooring damage, disturbance to and removal (looting/souvenir hunting) of artifacts, 

intentional and unintentional physical contact (body or equipment), and the interaction of exhaled air 

bubbles with the site (Edney, 2006). Sport divers may, however, have a beneficial impact to 

archaeological sites by monitoring sites, encouraging fellow divers to protect sites, and by reporting 

any observed adverse impacts to the appropriate State or Federal agency. Impacts to 

archaeological resources from sport diving range from beneficial to major. There is no 

archaeological mitigation applied to sport diving.

Research and Monitoring

Research and monitoring activities in the GOM are not quantified; however, it is possible to 

discuss a potential range of impacts to archaeological sites from them. Negative impacts to 

archaeological sites may result from seafloor disturbance such as specimen collection by bottom 
Description of the Affected Environment and Impact Analysis 4-369

trawling or geotechnical core sampling. Beneficial impacts may result from the visual identification 

and/or inspection of sites during ancillary scientific activities or the collection of environmental data 

that may be used to evaluate the condition of archaeological sites. Impacts to archaeological 

resources from research and monitoring range from beneficial to major. Archaeological mitigation 

may be recommended for research and monitoring if BOEM is (1) aware of the project and (2) is 

provided the opportunity to comment on the research design.

Hurricanes

Hurricanes and tropical storms are normal occurrences in the GOM and along the Gulf 

Coast. Shipwrecks in shallow waters are exposed to storm-induced wave action and a greatly 

intensified, longshore current during tropical storms (Clausen and Arnold, 1975). Under such 

conditions, there is a potential for hull components and artifacts (e.g., ceramics and glass) to be 

dispersed. Overall, a significant loss of data from sites has probably occurred, and would continue 

to occur, in the northern Gulf from the impacts of tropical storms. Impacts to archaeological 

resources from hurricanes range from negligible to major. BOEM does not apply any 

archaeological mitigation in advance of potential hurricane activity.

Incomplete or Unavailable Information

There is incomplete or unavailable information regarding the long-term impacts of oil and/or 

dispersant contamination on, and the location of, archaeological resources in the GOM. As 

discussed above, there are currently no published studies on the long-term impacts to 

archaeological resources exposed to oil or dispersant contamination. However, considering the low 

probability of an accidental oil spill contacting an archaeological site as a result of a proposed action, 

BOEM has determined that the information is not essential to a reasoned choice among alternatives.

Additionally, the locations of all archaeological resources in the GOM cannot be determined 

because the overall costs of obtaining that information through survey of the entire GOM are 

exorbitant. This incomplete information may be relevant to adverse impacts because the locations 

and integrity of many archaeological resources remain unknown. Nevertheless, this incomplete 

information is not likely to be available within the timeline contemplated in the NEPA analysis of this 

Multisale EIS. It would take several years before data confirming the presence (or lack thereof) of 

archaeological resources, and the status of each, could be investigated, analyzed, and compiled. 

Archaeological sites within the GOM have the potential to be buried, embedded in, or laying on the 

seafloor. The seafloor is comprised of highly variable bathymetric and geophysical regimes, which 

differentially affect the ease and ability to identify, ground truth, and evaluate archaeological sites. 

This fact, combined with the scope of the acreage within the GOM, 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, where required, help establish the presence of potential resources (NTL 2005-G07, 
4-370 Gulf of Mexico Multisale EIS

“Archaeological Resource Surveys and Reports”). 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 resources that are a 

part of the human environment. The survey data are analyzed by industry and BOEM’s 

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 effective in identifying resources to allow for mitigation application and protection 

of the resource during OCS oil- and gas-related activities. A 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 site-specific surveys, the results of which BOEM uses to require 

substantial avoidance of any potential resource that could be affected by the proposed activity. 

Therefore, BOEM has determined that the gaps in information on the presence of or status of 

archaeological resources is not essential to a reasoned choice among alternatives at the lease sale 

stage.

4.13.2.1 Alternatives A, B, C, and D

Regardless of which planning area a proposed lease sale is held, the greatest potential 

impact to an archaeological resource as a result of a proposed action under any of the action 

alternatives is site specific and would result from direct contact between an offshore activity (i.e., 

platform installation, drilling rig emplacement, decommissioning, or dredging or pipeline project) and 

a site. During postlease activities, each permitted action would be assessed for site-specific 

potential impacts during the permit application process. Archaeological surveys, where required 

prior to an operator beginning OCS oil- and gas-related activities on a lease, are expected to be 

effective at identifying possible archaeological sites. The technical requirements of the 

archaeological resource reports are detailed in NTL 2005-G07, “Archaeological Resource Surveys 

and Reports.” Under 30 CFR § 250.194(c) and 30 CFR § 250.1010(c), lessees are required to 

immediately notify BOEM’s and BSEE’s Regional Directors of the discovery of any potential 

archaeological resources.

Offshore oil- and gas-related activities resulting from a proposed action could impact an 

archaeological resource 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 unavailable. Such an event could result in the disturbance or 

destruction of important archaeological information. Archaeological surveys would provide the 

necessary information to develop mitigation strategies that would reduce the potential for impacts on 

archaeological resources.

Accidental events producing oil spills may threaten archaeological resources along the Gulf 

Coast. Should a spill contact an archaeological site, damage might include direct impact from oilspill cleanup equipment, contamination of materials, and/or looting. A major effect from an oil-spill 

impact would be contamination of a historic coastal site, such as a historic fort or lighthouse. It is 

expected that any spill cleanup operations would be considered a Federal action for the purposes of 
Description of the Affected Environment and Impact Analysis 4-371

Section 106 of the NHPA and would be conducted in such a way as to minimize to the extent 

possible impacts to archaeological resources. Recent research suggests the impact of direct 

contact of oil on historic properties may be long term and not easily reversible without risking 

damage to fragile historic materials (Chin and Church, 2010).

The potential for spills is low, the impacts of most noncatastrophic spills would generally be 

localized, and the cleanup efforts would be regulated. A proposed action, therefore, is not expected 

to result in impacts to archaeological sites; however, should such impacts occur, unique or 

substantial archaeological information could be lost and this impact could be irreversible.

There is also the potential for debris from vessels and offshore structures to be lost on the 

OCS. Debris resulting from accidental events could lead to impacts similar to those expected from 

routine impacts such as damage through contact with historic archaeological sites and/or the 

masking of archaeological resources during geophysical surveys.

There is no acceptable threshold of negative cumulative impacts to archaeological sites. A 

proposed action, including the drilling of wells and installation of platforms, installation of pipelines, 

anchoring, removal of platforms and other structures installed on the seafloor, and site clearance 

activities without archaeological review and mitigation may result in major impacts to archaeological 

sites. Identification, evaluation, and avoidance or mitigation of archaeological resources is expected 

to result in negligible long-term cumulative impacts to archeological resources as described in the 

previous section; however, if an archaeological site were to be impacted, impacts may range from 

negligible to major. 

4.13.2.2 Alternative E—No Action

If selected, Alternative E, the No Action Alternative, would result in BOEM not undertaking a 

proposed lease sale. Therefore, the impact-producing factors mentioned above would not take 

place, and any impact that these actions could cause would not occur. As a result, whatever 

archaeological resources may be present would not be affected in any way if the No Action 

Alternative is selected.

4.14 HUMAN RESOURCES AND LAND USE

4.14.1 Land Use and Coastal Infrastructure

For land use and coastal infrastructure, a proposed action would involve all of the Gulf Coast 

States: Texas; Louisiana; Mississippi; Alabama; and Florida. Particular emphasis is placed on the 

133 counties and parishes that constitute the 23 BOEM-identified EIAs and are located in the coastal 

areas of all five states. This geographic area is broadly diverse in types of land use and distribution 

of coastal infrastructure related to OCS oil- and gas-related activities. Some counties and parishes 

are more closely connected to the offshore oil and gas industry than others, such as Harris County, 

Texas, and Lafourche Parish, Louisiana. Figures 3-10, 3-11, and 3-12 illustrate the analysis area’s 

key infrastructure.
4-372 Gulf of Mexico Multisale EIS

Impacts to land use and coastal infrastructure may be positive as well as negative. For 

example, increased economic demand for services provided by infrastructure facilities would lead to 

more hiring, and this additional employment would further the positive economic trend as new 

workers spend their wages in the community. The impacts of each impact-producing factor are 

summarized in Table 4-26 using the impact-level definitions below. Negative and positive impacts 

are measured on that scale.

Impact-Level Definitions

• Negligible – Little or no measureable impact.

• Minor – Small-scale measurable impact, temporary in duration and 

geographically small area (less than county/parish level).

• Moderate – Medium-scale measurable impact and may last from a few weeks to 

1 year and geographically may affect multiple counties/parishes.

• Major – Large-scale measurable or potentially unmeasurable impact, long-lasting 

(1 year to many years), and may occur over a geographically large regional area.

A current snapshot of land use and coastal infrastructure in the GOM reveals a diverse social 

and economic landscape, with the oil and gas industry playing a substantially larger role in some 

states (i.e., Texas and Louisiana) than in the rest of the GOM. The oil and gas industry has 

developed across the region over decades and is intimately intertwined with its socioeconomic 

structure. This complex structure involves both onshore and offshore (State and Federal OCS) 

exploration, development, and production activities, complicating the environmental impact analysis 

because it is very difficult, if not impossible, to separate the impacts of Federal OCS oil- and gasrelated activities from those of oil and gas activities in State waters and onshore.

Oil and gas exploration, production, and development activities on the OCS are supported by 

an expansive onshore network of coastal infrastructure that includes large and small companies 

providing a wealth of services from construction facilities, service bases, and waste disposal facilities 

to crew, supply, and product transportation, as well as processing facilities. A description of the 

affected environment covers land use in the area and different infrastructure categories that support 

thousands of jobs. These jobs represent direct, indirect, and induced economic impacts that ripple 

through the Gulf Coast economy. As a long-standing part of the regional economy that developed 

over the past several decades, the coastal infrastructure network is quite mature in the Gulf of 

Mexico region. The affected environment is described in the following chapter and a discussion of 

the impacts of routine activities, accidental events, and cumulative impacts as they relate to land use 

and coastal infrastructure follows.
Description of the Affected Environment and Impact Analysis 4-373

Table 4-26. Land Use and Coastal Infrastructure Impact-Producing Factors.

Land Use and Coastal 

Infrastructure Magnitude of Potential Impact*

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Activities

Changes in the Level of 

OCS Exploration, 

Development, and 

Production Activities

Negligible to Negligible to Negligible to Negligible to

Negligible 

Moderate Moderate Moderate Moderate

Expansions of Existing 

Infrastructure

Minor to Minor to Minor to Minor to

Negligible Moderate Moderate Moderate Moderate

New Infrastructure 

Facility Construction

Minor to Minor to Minor to Minor to

Negligible Moderate Moderate Moderate Moderate

Onshore Waste 

Disposal 

Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Navigation Channel 

Maintenance Dredging

Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Accidental Events

Oil Spills (coastal and 

offshore)

Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Chemical/Drilling-Fluid 

Spills

Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Spill Response Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Vessel Collisions Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Cumulative Impacts

OCS Oil- and GasRelated Factors

Negligible to Negligible to Negligible to Negligible to Negligible Major Major Major Major

Non-OCS Oil- and GasRelated Factors

Negligible to Negligible to Negligible to Negligible to Negligible Major Major Major Major

* The magnitude of the impact depends on the scale and details of the event; therefore, the range for 

magnitude is generally broad (negligible to moderate or negligible to major).

4.14.1.1 Description of the Affected Environment

Socioeconomic Analysis Area

Along the Gulf Coast, from the southern tip of Cameron County, Texas, to the Florida Keys, 

23 BOEM-defined EIAs are identified for the Gulf of Mexico region. The counties and parishes that 

form the EIAs are listed and the EIAs are visually illustrated on Figure 4-27. The EIAs 

geographically link together not only counties and parishes immediately adjacent to the GOM but 

also those tied to coastal counties and parishes as parts of functional economic areas. An analysis 
4-374 Gulf of Mexico Multisale EIS

that encompasses where people live as well as where they work permits a more meaningful 

assessment of the impact of offshore oil and gas activities. The OCS oil- and gas-related activities 

draw on existing infrastructural, economic, and labor capacity from across the GOM region. BOEM’s 

analysis considers the potential impacts in all 23 EIAs regardless of where a proposed action may 

take place.

Land Use

The coastal zone of the GOM is not a physically, culturally, or economically homogenous unit 

(Gramling, 1984). The counties and parishes along the Gulf Coast represent some of the most 

valuable coastline in the U.S. and cover approximately 1,631 mi (2,625 km). Not only does it include 

miles of recreational beaches and an extended system of barrier islands, but it also has deepwater 

ports, oil and gas support industries, manufacturing, farming, ranching, and hundreds of thousands 

of acres of wetlands and protected habitat. These counties and parishes vary in their histories and 

in the composition and economic activities of their respective local governments.

The Gulf coastal plain of Texas makes up most of eastern and southern Texas and 

constitutes more than one-third of the State. Near the coast, this region is mostly flat and low-lying. 

It rises gradually to 1,000 ft (300 m) farther inland, where the land becomes more rolling. Belts of 

low hills occur across the Gulf coastal plain in many areas. In the higher areas, the stream valleys 

are deeper and sharper than those along the coast. Texas’ coastline along the GOM is 367 mi 

(591 km). However, long narrow islands called barrier islands extend along the coast; if the 

shoreline of all the islands and bays is taken into account, the coastline is 3,359 mi (5,406 km) long. 

The region is made up of farmland (i.e., cotton, rice, and citrus fruit), forests, cattle ranches, major 

cities of commerce (e.g., Houston) and education, tourist locales (e.g., South Padre Island), Federal 

installations (e.g., Lyndon B. Johnson Space Center), and major ports. The oil and gas industry has 

also been part of the local economies since the early 1900’s. Today, the majority of oil and gas 

corporations have headquarters in Houston while numerous industries associated with oil and gas 

(i.e., petrochemicals and the manufacture of equipment) are located in the area. In addition to oil 

and gas, the area has aggressively pursued technology companies such as computers and 

aerospace. The military has had a significant presence in general, particularly in the Corpus Christi 

Bay area, and more recently in San Patricio County on the eastern shore of the bay (Petterson et al., 

2008).

The Louisiana coastal area includes broad expanses of coastal marshes and swamps 

interspersed with ridges of higher well-drained land along the courses of modern and extinct river 

systems. Most of the urban centers in coastal Louisiana are located along major navigable rivers 

and along the landward edge of the coastal zone (i.e., Lafayette and Lake Charles). Southwestern 

Louisiana is Acadian country. The area’s natural features vary from marshland, waterways, and 

bayous in the coastal areas to flat agricultural lands in the northern part of the same parishes. While 

the area’s traditionally strong ties to agriculture, fishing, and trapping are still evident, they are no 

longer the mainstay of the economy. Southeastern Louisiana, from Jefferson Parish east to St. 

Tammany Parish and the State border with Mississippi, is a thriving metropolitan area with shipping, 
Description of the Affected Environment and Impact Analysis 4-375

navigation, U.S. Navy facilities, and oil and chemical refineries, all vying with local residents for land 

(Petterson et al., 2008). Historically, Terrebonne, Plaquemines, and Lafourche Parishes have been 

the primary staging and support area for offshore oil and gas exploration and development. The 

Port of Fourchon, at the mouth of Bayou Lafourche on the GOM, is a major onshore staging area for 

OCS oil- and gas-related activities in the GOM, and it is the headquarters of the Louisiana Offshore 

Oil Port (LOOP), which offloads 10 percent of U.S. foreign oil imports and transports that oil to half of 

the Nation’s refining capacity and services over 90 percent of deepwater GOM production (The 

Greater Lafourche Port Commission, 2015). The LOOP has received and transferred over 11 billion 

barrels of crude oil since its inception (LOOP LLC, 2015).

Coastal Mississippi is characterized by bays, deltas, marshland, and waterways. Two-thirds 

of this coast is devoted to State-chartered gambling barges and heavy tourism along the beachfront. 

The remaining one-third (Jackson County) is industrial—oil refining and shipbuilding. Upland 

portions of the three coastal counties—Hancock, Harrison, and Jackson—are timberlands (Petterson 

et al., 2008). Jackson County has a strong industrial base and designated industrial parks. 

Pascagoula, in Jackson County, is home to Ingalls Shipbuilding, an 800-ac (324-ha) shipyard that 

employs 11,000 people, and the Chevron Pascagoula Refinery located in the Bayou Casotte 

Industrial Park (Ingalls Shipbuilding, 2015; Chevron, 2015). The Port of Pascagoula is one of the top 

20 ports in the U.S. by foreign cargo volume, handling forest products, chemicals, crude oil, 

phosphate rock, and aggregate. The port includes the Pascagoula River Harbor and the Bayou 

Casotte Harbor (Port of Pascagoula, 2015). Now in a state of expansion after recovering from 

Hurricane Katrina damages, the Port of Gulfport houses some major OCS oil- and gas-related

companies (i.e., shipbuilding, shipyards, pipelaying, and offshore support services) in addition to 

food importers, casino operations, university research activities, and renewable energy interests 

(Port of Gulfport, 2016).

Southwestern Alabama’s coastline is comprised of Mobile and Baldwin Counties, which 

oppose each other across Mobile Bay. Coastal resource-dependent industries in this area include 

navigation, tourism, marine recreation, commercial fishing, and offshore natural gas development 

and production. Large quantities of natural gas were discovered in Alabama’s offshore waters in 

1979. Baldwin County has a strong tourism economy and a large retiree population. The important 

commercial fishing industry in the area is located in southeastern Mobile County. The Port of 

Mobile, the largest seaport in Alabama, is also in Mobile County. The military has had a long 

presence in the area. The buildup and downsizing of military installations has handed the area 

some special challenges. The area’s second port, Mobile Middle Bay Port, is a former Naval 

Station. Major manufacturers in Mobile include three paper mills, a German-owned chemical plant, 

and two large shipbuilding and repair yards (Petterson et al., 2008). Mobile County has a strong 

industrial base and designated industrial parks, especially at Theodore Industrial Park and Canal 

and the Alabama State Docks. In addition, Bayou La Batre in south Mobile County has many 

shipbuilding firms. Theodore, in Mobile County, has boat and helicopter facilities, and onshore 

supply bases to support drilling and production (Dismukes, 2011).
4-376 Gulf of Mexico Multisale EIS

The GOM coastal area of Florida includes bays, estuaries, wetlands, an extensive barrier 

island system, and increasing concentrations of human settlement. This area ranges from heavily 

urbanized areas, such as Pensacola in Escambia County and Panama City in Bay County with 

shipping ports and Naval air bases, to scarcely populated areas along the coastal rim, such as the 

towns of Port St. Joe, Apalachicola, and Carrabelle in Gulf and Franklin Counties. The Florida 

Panhandle area has military, tourism, fishing, and ports as major components of the economy. The 

military has had a substantial presence in the Florida Panhandle since World War II. The four main 

military installations are Pensacola Naval Air Station, Eglin Air Force Base (Okaloosa County), 

Tyndall Air Force Base, and the Coastal Systems Station (Bay County). The three air bases use the 

northern GOM as a weapon-testing and training range. These bases were largely untouched by the 

downsizing of the military in the 1990’s and remain an important part of the Florida Panhandle 

economy. Tourism and recreation are extremely important to the area, along with both commercial 

and recreational fishing activities. The development of the Florida Panhandle as a major tourist area 

began in the mid-1930’s and grew rapidly after World War II, becoming what is now a key industry in 

the Florida Panhandle. “Sugar-white” beaches, fishing, other water-based activities, and natural 

habitats are key parts of the tourist attraction. In the Florida Panhandle, the commercial fishing 

industry employs several hundred people, who land millions of pounds of fish and shellfish annually 

(Petterson et al., 2008). Three major deepwater ports are Port of Pensacola, Port Panama City, and 

Port Tampa Bay. The Port of Pensacola is turning away from bulk container cargo and focusing on 

expanding operations to cater to the oil and gas industry, and new projects such as deep-sea pipe 

manufacturing have begun development (Offshore Inland, 2014; DeepFlex, 2014; Pensacola News 

Journal, 2014). Port Panama City served as an onshore support base for exploratory drilling in the 

GOM during the 1980’s before drilling was banned in most of the EPA. Since that time the Port has 

continued diversifying and has initiated the development of the Port Panama City Intermodal 

Distribution Center to attract more businesses to the area. Most of the Port handles bulk container 

cargo, seafood products, and some petroleum products (Dehart, 2013; World Port Source, 2015).

The U.S. Dept. of Agriculture’s Economic Research Service classifies counties (includes 

parishes) into economic types that indicate primary land-use patterns. According to the most recent 

statistics, most notably only 7 of the 133 counties in the analysis area are classified as farming 

dependent. Ten counties are defined as mining dependent, suggesting the importance of oil and 

gas development to these local economies. Manufacturing dependence is noted for another 

26 counties. Local school districts and public facilities, such as hospitals and prisons, are often the 

largest employers in sparsely populated rural areas. Thus, it is not surprising that 19 non-metro 

counties and 13 metropolitan counties are classified as government employment centers. Another 

21 counties have economies tied to service employment while 37 counties are considered 

nonspecialized. The Economic Research Service also classifies counties in terms of their status as 

a retirement destination, and of the 133 counties/parishes, 44 are considered major retirement 

destinations (U.S. Dept. of Agriculture, Economic Research Service, 2008). The varied land-use 

patterns are displayed in Figure 4-27. 
Description of the Affected Environment and Impact Analysis

4-377

Figure 4-27. Economic Land Use Patterns.
4-378 Gulf of Mexico Multisale EIS

Coastal Infrastructure

The onshore coastal infrastructure is extensive, covers a wide-ranging area, supports 

development, and consists of thousands of large and small companies. These companies cover 

every facet of coastal and offshore industry activity, but for analysis purposes, these infrastructure 

types are organized into the following categories: construction facilities; support facilities; 

transportation; and processing facilities. More extensive information on OCS oil- and gas-related 

coastal infrastructure can be found in Chapter 3.1.7. 

Construction Facilities

The major players among construction facilities in the coastal GOM include platform 

fabrication yards (Chapter 3.1.7.1.1), shipbuilding and shipyards (Chapter 3.1.7.1.2), and pipecoating plants and yards (Chapter 3.1.7.1.3). These facilities’ service involves both onshore and 

offshore (State and Federal OCS) oil and gas exploration, development, and production activities. 

Shipbuilding and shipyards may also be servicing the commercial and recreational fishing industry or 

the military. This can complicate impact analysis because of the difficulty inherent in trying to 

separate the impacts of OCS oil- and gas-related activities from non-OCS oil- and gas-related 

activities, given that they utilize the same critical coastal infrastructure.

Support Facilities

The major support facilities in the coastal GOM include service bases and ports, waste 

disposal facilities, and natural gas storage facilities. State and Federal (both onshore and offshore) 

oil and gas exploration, development, and production activities utilize the same critical coastal 

support infrastructure. Other types of support sectors to the oil and gas industry that may have 

coastal facilities can include drilling contractors, geological and geophysical contractors, underwater 

contractors (divers and remotely operated vehicle equipment). Ports and service bases are also 

used for international and domestic import and export activities, and service other industries 

including commercial and recreational fishing, cruise ship terminals, and research vessels. Maritime 

military operations generally have their own ports and bases along the coast, but they may use 

community waste disposal facilities.

Transportation

The major forms of crew, supply, and product transportation include the following: heliports; 

coastal pipelines/pipeline landfalls/pipeline shore facilities; and coastal barging/barge terminals. 

These transportation services can involve both onshore and offshore (State and Federal OCS) 

exploration, development, and production activities. This complicates impact analysis because of 

the difficulty inherent in trying to separate the impacts of OCS oil- and gas-related activities from 

non-OCS oil- and gas-related activities, given that they utilize the same coastal infrastructure. 

Critical to the success of service bases and port facilities are the railways and major interstates that 

traverse the areas along the inner margin of the coastal zone. There are nine interstate highways 

that access the regional area; however, there are numerous other highways into and across the 
Description of the Affected Environment and Impact Analysis 4-379

analysis area. The most critical is Louisiana Highway 1 (LA Hwy 1) that provides the only link 

between Port Fourchon, Louisiana, and the rest of the Nation.

Processing Facilities

The major forms of processing facilities in the coastal GOM include gas processing plants, 

LNG terminals, refineries, and petrochemical plants. Basic chemical production from petrochemical 

plants is concentrated along the Gulf Coast, where petroleum and natural gas feedstock are 

available from refineries. Of the top 10 production complexes in the world, 5 are located in Texas 

and 1 is located in Louisiana. These facilities can process onshore and offshore (State and Federal 

OCS) production and foreign imported production. This complicates impact analysis because of the 

difficulty inherent in trying to separate the impacts of OCS oil- and gas-related activities from nonOCS oil- and gas-related activities, given that they utilize the same critical coastal infrastructure for 

downstream processing of their products.

4.14.1.2 Environmental Consequences

Analysis and discussion of impact-producing factors from routine activities, accidental events 

(non-catastrophic), and cumulative activities follow below. For a detailed analysis of a high-impact, 

low-probability catastrophic oil spill, which is not reasonably foreseeable as a result of a proposed 

action, refer to the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2016c).

Routine Activities

Routine activities of the oil and gas industry result in various impact-producing factors that 

could affect land use and coastal infrastructure, including the following: fluctuations in the level of 

OCS exploration, development, and production activities; expansions of existing facilities; 

construction of new facilities; onshore disposal of OCS waste; and maintenance dredging of existing 

navigation channels. These routine activities impact, to some extent, each of the infrastructure types 

discussed in the “Affected Environment” section above, including construction facilities, support 

services, transportation modes for people and products, and processing facilities. However, the 

impacts of these factors on land use and coastal infrastructure are mainly negligible to minor

because oil- and gas-related coastal infrastructure is a mature and extensive system, resulting from 

long-term industry trends, and it is not subject to rapid fluctuations. Routine activities related to a 

proposed action are expected to minimally affect the current land use of the analysis area because 

most subareas have strong industrial bases and designated industrial parks with existing 

infrastructure and facilities that have sufficient capacity to accommodate future growth. For this 

reason, land use conflicts are not likely to occur.

Fluctuations in OCS exploration, development, and production activity levels can impact land 

use and coastal infrastructure because higher activity levels increase demand for services, which 

can affect land use if a facility needs to acquire additional land for expansion to meet the demand, 

and it would affect infrastructure facilities by potentially increasing profits and the need to hire 

additional employees. This would be a positive impact and could cause localized expansion of 
4-380 Gulf of Mexico Multisale EIS

economies (i.e., increased demand for services, consumer spending, and indirectly, new 

employment), resulting in localized land-use changes including commercial and residential 

development and growth. If activity levels decrease, then the opposite impact occurs. Decreases in 

demand for services could cause a negative ripple impact through the local (and possibly regional) 

economies. The OCS activity levels fluctuate based on changes in demand, commodity prices, and 

offshore service vessel day rates (for shipyards, shipbuilding, and transportation services). When 

activity levels increase, commuter and truck traffic increase, producing additional wear and tear on 

the transportation infrastructure. For example, LA Hwy 1 is the only road providing critical access to 

Port Fourchon, the largest OCS oil- and gas-related service base, which supports 90 percent of all 

OCS deepwater activities. Whether positive or negative, the impacts described above range from 

negligible to moderate depending on the specific situation, type of infrastructure facility being 

considered, and its location. For example, a small-scale expansion of a waste disposal facility that is 

already located in a remote area would be a negligible impact. If the facility was located in a more 

populated area, it may cause temporary disruption to traffic from construction activities and thus be a 

minor impact. If it was a larger-scale expansion and the facility was located in a more populated 

area, then the impact would be moderate because the scale of the project would make the 

disruption last anywhere from a few weeks to a year.

Land use and coastal infrastructure may also be affected by expansions of current facilities 

that result from oil and gas industry-generated service demand increases. Because of the 

environmental and regulatory difficulties inherent in permitting and building new facilities, most 

companies would opt to expand their existing facilities (i.e., fabrication yards, shipyards, pipe-coating 

facilities, service bases, refineries, gas processing plants, and waste disposal facilities). Expansions 

of existing facilities generate a positive momentum with increased capabilities leading to increased 

profitability. Whether positive or negative, the impacts described above range from facility 

expansions ranges from minor to moderate depending on the specific situation. For example, a 

small-scale expansion of a refinery would be a minor impact because of the small size of the 

project, the temporary disruptions caused by increased constructions traffic and the geographically 

small area affected. If the refinery was located in a more populated area and the project was larger 

in scale, causing disruptions because of construction activities that last up to one year, then the 

impact would be moderate. BOEM’s scenario projections forecast most increases in demand to be 

met by expansions at currently existing facilities (Dismukes, official communication, 2015).

Much less common in the GOM, the construction of new facilities requires substantial capital 

investment and assurances of future service demand to make this option attractive to investors. 

BOEM’s scenario projections call for possibly 0-1 new gas processing plant and 0-1 new pipeline 

landfall during the 50-year analysis period for a proposed lease sale (Dismukes, official 

communication, 2015). If either were to occur, it may negatively impact land use because of 

potential space-use conflicts, and some gas processing facilities also could be negatively impacted 

because it may become necessary to increase efforts to maintain competitiveness. In the rare 

instance of new facility construction, the impacts would range from minor to moderate depending 

on the nature and location of the project(s).
Description of the Affected Environment and Impact Analysis 4-381

The OCS oil- and gas-related waste disposal to onshore facilities is an impact-producing 

factor that could affect onshore waste disposal facilities and land use if a new facility needs to be 

constructed to meet the level of offshore wastes coming to shore. Chapter 3.1.5.3 discusses OCS 

oil- and gas-related waste disposal and outlines BOEM’s scenario analysis, which concluded that no 

new solid-waste facilities would be built as a result of a single lease sale. Existing solid-waste 

disposal infrastructure is adequate to support both existing and projected offshore oil and gas drilling 

and production needs. The industry trend is toward innovative methods to handle wastes to reduce 

the potential for environmental impacts, e.g., hydrocarbon recovery/recycling programs, slurry 

fracture injection, treating wastes for reuse as road base or levee fill, and segregating waste streams 

to reduce treatment time and improve oil recovery. The volume of OCS waste generated is closely 

correlated with the level of offshore drilling and production activity (Dismukes et al., 2007, Dismukes, 

2011, Dismukes, official communication, 2015). The impact of fluctuations in offshore waste 

disposal would range from negligible to minor and would not be expected to result in more 

extensive impacts because existing spare capacity of current facilities is sufficient to meet demand.

Maintenance dredging of existing navigation channels is essential for proper water depths to 

allow all shipping to move safely through the waterways to ports, services bases, and terminal 

facilities. Several million cubic yards of sand, gravel, and silt are dredged from waterways and 

harbors every year. Chapter 3.1.4.6 discusses scenario projections for navigation channels along 

the Gulf Coast. Much of the traffic navigating these channels is unrelated to OCS oil- and gasrelated activity, and the current system of navigation channels in the northern GOM is projected to 

be adequate for accommodating traffic generated by a proposed lease sale. Therefore, no new 

navigation channels are expected to be created as a result of a proposed lease sale (Dismukes, 

2011; Dismukes, official communication, 2015). Chapter 4.3.2 provides a discussion of wetlands 

and the impacts of navigation channel dredging. Impacts to land use and coastal infrastructure as a 

result of maintenance dredging are expected to range from negligible to minor depending on the 

location of dredging projects.

Routine activities are not expected to produce any major impacts to land use and coastal 

infrastructure because current supporting oil and gas infrastructure is mature and not subject to rapid 

changes. As OCS oil- and gas-related activity levels fluctuate, the demand for services provided by 

coastal infrastructure facilities would fluctuate. If necessary, increases in demand would be met with 

facility expansions. Regarding new construction, BOEM’s scenario projections call for up to one new 

gas processing facility, up to one new pipeline landfall over the 50-year life of a proposed lease sale, 

and no new waste disposal facilities. The impacts on land use and coastal infrastructure would be 

limited, would occur on lands designated for such purposes, and would be negligible to moderate

because the projected addition to infrastructure is so small. Maintenance dredging of navigation 

channels as a result of a proposed lease sale is expected to produce negligible to minor impacts to 

land use and coastal infrastructure (Dismukes, official communication, 2015).
4-382 Gulf of Mexico Multisale EIS

Accidental Events

Impact-producing factors associated with accidental events that may affect land use and 

coastal infrastructure include coastal and offshore oil spills, chemical/drilling fluid spills, spillresponse activities, and vessel collisions. Accidental events associated with a proposed action 

would occur at differing levels of severity, based in part on the location and size of event. Coastal 

and offshore oil-spill events discussed in this section are noncatastrophic in nature, smaller in size, 

occur more frequently, and must be distinguished from low-probability catastrophic oil spills such as 

the Deepwater Horizon blowout, oil spill, and response. Chapter 3.2.1 provides a detailed 

discussion of oil spills that have occurred and their frequency. A complete analysis of a high-impact, 

low-probability catastrophic oil spill is provided in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2016c).

Coastal and offshore oil spills may be associated with OCS exploration, production, or 

transportation activities that result from a proposed lease sale. Detailed risk analysis of offshore oil 

spills ≥1,000 bbl, <1,000 bbl, and coastal spills associated with a proposed lease sale is provided in 

Chapters 3.2.1.3, 3.2.1.4, and 3.2.1.5. Because oil spilled in the offshore areas normally volatilizes 

and is dispersed by currents, it has a low probability of contacting coastal areas. Oil spills in coastal 

and inland waters, such as spills resulting from the operations of offshore supply vessels, pipelines, 

barges, tanker ships, and ports, are more likely to affect BOEM-recognized coastal infrastructure 

categories. For example, if waterways are closed to traffic, this may result in impacts to upstream 

and downstream business interests as it impedes the flow of commerce. Other potential impacts 

could include damages to private and public lands, personal injury, damages to collateral property 

(moveable property such as vehicles and boats), and economic damages from the disruption of 

business. The impacts to land use and coastal infrastructure from coastal and offshore oil spills 

could range from minor to major depending on the size and location of the spill and whether it is 

catastrophic or not. More specifically, the intensity of the impact would be experienced 

inconsistently among businesses and residents, meaning it would be worse for some 

businesses/residents than others. For example, those who have alternative means of transporting 

their goods would not feel the impact as harshly as those who are most dependent on the waterway 

for transport. The mean number and sizes of spills estimated to occur in OCS offshore waters from 

an accident related to rig/platform and pipeline activities supporting a proposed action over a 50-year 

period are presented in Table 3-17. 

Chemical/drilling-fluid spills may affect land use and coastal infrastructure and could be 

associated with exploration, production, or transportation activities that result from a proposed lease 

sale. Chapter 3.2.6 provides a detailed discussion of chemical and drilling-fluid spills. Each year, 

between 5 and 15 chemical spills are expected to occur; most of these are ≤50 bbl in size. Large 

spills are much less frequent. Even though additional production chemicals are needed in 

deepwater operations where hydrate formation is a possibility, spill volumes are expected to remain 

stable because of advances in subsea processing. Overall, the impact of chemical and drilling-fluid 

spills is expected to be negligible to moderate depending on the location, size, and duration of the 

event. For example, potential impacts could include damages to private and public lands, personal 
Description of the Affected Environment and Impact Analysis 4-383

injury, damages to collateral property (moveable property such as vehicles and boats), and 

economic damages from the disruption of business. If a spill is very small (not measurable) in size, 

located in a remote area, and dissipates quickly, its impact would be negligible. If a spill is 

measurable, occurs in a less remote area, and lasts a few days to a month, then its impact would be 

minor. If a spill occurs in a highly populated area, is larger in quantity, and the response and 

cleanup last over a month and up to a year with either waterborne commerce affected and/or land 

transportation affected, then the impact would be moderate. 

While not an accidental event specifically, spill response results from an accidental spill and 

is included here accordingly. Spill-response activities may affect land use and coastal infrastructure 

because of the requisite needs for staging operations, equipment handling, and waste disposal. 

Depending on where an accidental event occurs, it is expected that the oil-spill response equipment 

needed to respond to an offshore spill as a result of a proposed lease could be called out from one 

or more of the following oil-spill equipment base locations: Aransas Pass, Baytown, Corpus Christi, 

Galveston, Houston, Ingleside, Pasadena, and Port Arthur, Texas; Baton Rouge, Belle Chasse, Fort 

Jackson, Franklin, Grand Isle, Harvey, Houma, Lake Charles, New Iberia, Port Fourchon, and 

Sulphur, Louisiana; Kiln and Pascagoula, Mississippi; Bayou La Batre and Mobile, Alabama; Key 

West, Miami, Panama City, Pensacola, and Tampa, Florida (Marine Spill Response Corporation, 

2015b; National Response Corporation, 2015). The impact of spill-response activities on land use 

and coastal infrastructure would range from negligible to moderate depending on the spill’s 

location, duration, and whether the event is a small-scale spill or a larger spill. For example, 

potential impacts could include space-use conflicts related to staging operations, potential 

mishandling of cleanup equipment (boom), and improper disposal of oily wastes. In addition, the 

additional use of waterways or roadways used for the vehicles servicing spill response may result in 

localized increased wear and tear.

Vessel collisions may be associated with exploration, production, or transportation activities 

that result from a proposed lease sale. Chapter 3.2.5 provides a detailed discussion of vessel 

collisions. The majority of offshore vessel collisions involve service vessels colliding with platforms 

or pipeline risers, although sometimes vessels collide with each other. In coastal waters, vessel 

collisions are more likely to include other vessels or stationary structures like bridges and docks. 

Human error accounted for about half of all reported vessel collisions from 1996 through 2009. 

These collisions often result in spills of various substances and, while most occur on the OCS far 

from shore, spills in coastal waters can have impacts to land use and coastal infrastructure that can 

range from negligible to moderate, depending on the severity and location of a vessel collision, the 

size of the vessels involved, and whether the collision involves a bridge, pier, or other structure. 

Land use may be affected if a bridge, pier, or other structure is involved because it could affect the 

transportation of goods, services, and people to and from work and schools.

The impact of reasonably foreseeable oil spills, chemical and drilling-fluid spills, and vessel 

collisions are not likely to last long enough to adversely impact overall land use or coastal 

infrastructure in the analysis area. Spill-response impacts would depend on the location and 

duration of a spill and whether or not it is a catastrophic event.
4-384 Gulf of Mexico Multisale EIS

Cumulative Impacts

Land use and coastal infrastructure experience cumulative impacts that include all human 

activities and natural processes and events. This cumulative analysis considers impacts that 

comprise the incremental contribution of a proposed lease sale combined with all past, present, and 

reasonably foreseeable future Federal OCS oil- and gas-related lease sales and activities, as well as 

all past, present, and reasonably foreseeable future actions unrelated to the Federal OCS oil- and 

gas-related activities (Chapter 3.3). Within this divided analytical framework of OCS oil-and gasrelated and non-OCS oil- and gas-related impacts, the largest quantity of impact-producing factors 

for land use and coastal infrastructure occur as non-OCS impacts because these resources are 

located onshore and exist for the benefit of both offshore and onshore oil- and gas-related activities, 

as well as other societal and business needs. Land use and coastal infrastructure occur within a 

complex socioeconomic structure, and OCS oil- and gas-related activities comprise a very small 

portion of this structure. Overall, cumulative impacts of all past, present, and reasonably 

foreseeable future OCS and non-OCS oil- and-gas related activities would range from negligible to 

major depending on the specifics of each situation, whether the impacts are measurable, how long 

the impacts would last, and the size of the affected geographic area.

OCS Oil- and Gas-Related Impacts

Potential impacts related to OCS oil- and gas-related activities include the cumulative impact 

of all past, present, and future lease sales, and the resultant exploration, development, and 

production in Federal waters that contribute to the following possible impacts: fluctuations in OCS 

oil- and gas-related activity levels; increases in commuter and truck traffic; onshore infrastructure 

expansions; construction of new infrastructure facilities; increases in waste disposal volumes; 

coastal and offshore oil spills, chemical/drilling-fluid spills, spill-response activities, and vessel 

collisions, which are all discussed above under “Routine Activities.” A proposed lease sale would 

make a minor incremental contribution to the cumulative impact of all past, present, and future lease 

sales. 

The OCS oil- and gas-related onshore coastal infrastructure is extensive, covers a wideranging area, supports OCS development, and consists of thousands of large and small

companies. Chapter 3.3.1.10 describes the cumulative scenario projections for the OCS Program. 

BOEM estimates no additional service bases, heliports, platform fabrication yards, shipyards, or 

pipe-coating yards. Lease sales would serve mostly to maintain ongoing activity levels associated 

with the current OCS Program. Industry would more or less maintain its current usage of 

infrastructure. Expectations for new gas processing facilities being built during the 70-year analysis 

period as a direct result of the OCS Program are dependent on long-term market trends that are not 

easily predicable over the next 70 years. Existing facilities would experience equipment switch-outs 

or upgrades during this time. BOEM projects that expansions at existing LNG facilities and the 

construction of new facilities would not occur as a direct result of the OCS Program. Cumulative 

impacts of OCS oil- and gas-related activities are dependent on fluctuations in OCS activity levels; 

increases in commuter and truck traffic; expansions at existing facilities; new construction of 

infrastructure; increases in waste disposal volumes; and accidental events such as coastal and 
Description of the Affected Environment and Impact Analysis 4-385

offshore oil spills, chemical/drilling-fluid spills, spill-response activities, and vessel collisions. 

BOEM’s scenario projections call for the new construction of 0-1 new gas processing facility and 

0-1 new pipeline landfall to result from a proposed lease sale over the analysis period. Increases in 

demand for services at other facilities would be met by current excess capacity or expansions at 

current facilities. These activities, along with noncatastrophic accidental events, are reasonably 

foreseeable.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil and gas-related cumulative impacts encompass all human activities and natural 

processes that may affect land use and coastal infrastructure, the list of which is beyond the scope 

of this NEPA analysis. Therefore, BOEM limits this cumulative analysis to the following most 

relevant (past, present, and reasonably foreseeable future) impact-producing factors:

• State oil and gas activity; 

• onshore oil and gas activities; 

• demands on transportation systems and ports;

• maintenance and improvements to transportation systems; 

• construction and maintenance of industrial facilities;

• agricultural uses;

• urbanization;

• demographic shifts (i.e., in-migration and out-migration);

• evolution of State and Federal regulations; 

• city planning and zoning; 

• development of residential areas and recreational facilities;

• modifications to public facilities such as water, sewer, educational, and health

facilities; 

• military activities;

• coastal land loss;

• coastal storms; and

• global, national, and regional economic trends.

All of the cumulative non-OCS oil- and gas-related impacts discussed in this section can 

range across the scale of intensity, i.e., from negligible to major depending on the unique specifics 

of each situation, whether the impacts are measurable, how impacts are measured, how long they 

would last, the size of the affected area, and often, the viewpoints of the various people that may be 
4-386 Gulf of Mexico Multisale EIS

involved. For example, in the case of urbanization, land developers would say any negative impacts 

are minor or negligible because they would be out-weighed by the positive economic benefits to the 

area (i.e., jobs, increased tax revenues, etc.), but a conservationist would say the impacts are major, 

negative, and highly detrimental because of habitat loss and damages to air and water quality. 

Given that within each listed category above there can be a myriad of potential situations that arise 

across the very large (133 counties and parishes) Gulf Coast analysis area, the discussion below 

would not assign individual labels (i.e., negligible, minor, moderate, or major) to each category of 

cumulative impact described.

Non-OCS oil- and gas-related activities onshore and in State waters utilize many of the same 

coastal infrastructure facilities as offshore OCS oil- and gas-related activities (Figure 3-10) and 

would continue to contribute to the cumulative impacts on land use and coastal infrastructure 

throughout the 70-year analysis period. Over the past several years, there has been a substantial

decrease in offshore natural gas production, partially as a result of increasing emphasis on 

onshore shale gas development, which is less expensive to produce and which provides larger

per-well production opportunities and reserve growth. Onshore unconventional natural gas

production has increased to the point that existing Gulf Coast LNG facilities are seeking to export 

natural gas to foreign consumers. For all coastal infrastructure types, especially processing 

facilities, it has proven impossible to parse out what percentage of demand is generated by OCS oiland gas-related activities as opposed to non-OCS oil- and gas-related activities. This difficulty is an 

inherent problem in analyzing most cumulative impacts to coastal land use and infrastructure.

For example, demands on transportation systems and ports are not isolated to OCS oil- and 

gas-related activities. Transportation systems (e.g., rail, trucks, highways, barges, supply vessels, 

and tankers) and ports also serve oil and gas activities onshore and in State waters, as well as other 

industrial uses unrelated to oil and gas activities (e.g., agricultural and manufacturing transport, and 

commercial and recreational fishing). The maintenance and improvements necessary for 

transportation systems and ports also are likely to cause cumulative impacts to land use and coastal 

infrastructure, in varying degrees, depending on the magnitude of each project. Similarly, 

construction or expansion and maintenance of non-OCS-related industrial facilities, such as paper 

mills and aluminum plants, could contribute to cumulative impacts on land use and coastal 

infrastructure depending on proximity and scale of the work being done.

Agricultural uses may also contribute to cumulative impacts on land use and coastal 

infrastructure. Of the over 400,000 mi2 (1,035,995 km2

) comprising these coastal states, 18 percent 

of the total land area is covered in cropland, which includes cropland harvested, crop failure,

cultivated summer fallow, cropland used only for pasture, and idle cropland. Texas and Mississippi 

have the highest percentages of cropland, with 20 percent and 19 percent of each respective 

state’s total land being used for cropland. Texas leads the Nation in cattle, cotton, hay, sheep, and 

wool. Texas also leads the Nation in the number of farms and ranches, with 247,500 farms and 

ranches covering 130.4 million ac (52.8 million ha). For all four coastal states, 42 percent of the 

total land area is used for grassland pasture and range, with Texas devoting 61 percent or close to

262,000 mi2 (679,095 km2

) for grassland pasture and range. Agriculture places many demands on 
Description of the Affected Environment and Impact Analysis 4-387

the environment and produces impacts that include, but are not limited to, habitat fragmentation, 

pesticide and nutrient runoff, competing urban and agricultural water needs, changes to watershed

hydrology, and changes in soil quality. Both State and Federal entities regulate various farming 

and ranching practices through laws such as the Clean Water Act, which establishes pollutant 

standards for many of the inputs used in conventional farming methods (Lubowski et al., 2006).

Cumulative impacts of urbanization on land use and coastal infrastructure affect the Gulf of 

Mexico EIAs with the highest numbers of people. Demographic shifts as people move in and out of 

areas contribute to the cumulative impacts on land use and coastal infrastructure. Census urban

areas include densely populated areas with at least 50,000 people (“urbanized areas”) and 

densely populated areas with 2,500-50,000 people (“urban clusters”). Included in the Census 

urban area definition are residential areas and concentrations of nonresidential urban areas such as

commercial, industrial, and institutional land; office areas; urban streets and roads; major airports;

urban parks and recreational areas; and other land within urban defined areas. Development takes

the place of natural ecosystems and fragments habitat. It also influences decisions people make 

about how to get around and determines how much people must travel to meet daily needs. These 

mobility and travel decisions have indirect impacts on human health and the natural environment 

by affecting air and water pollution levels. Impacts of urbanization include habitat fragmentation, 

reduced water and air qualities, and the urban heat island impact. On the other hand, residents of 

cities live in smaller homes and drive less because of the close proximity of amenities. Future

trends in urban land use would be largely determined by economics, demographic shifts, local

ordinances, and zoning (USEPA, 2013c).

Within the geo-political realm, non-OCS related cumulative impacts on land use and coastal 

infrastructure could also include evolving State and Federal regulations (especially environmental),

city planning and zoning, residential development, recreational facilities, public facilities (i.e., water, 

sewer, health, and education), and military activities. Land- use patterns vary greatly by region, 

reflecting differences in soils, climate, topography, and patterns of population settlement. Landuse changes would largely depend upon local zoning and economic trends. Mississippi and 

Louisiana are located in what the U.S. Department of Agriculture’s Economic Research Service 

calls the Delta farm production region, while Alabama is located in the Southeast farm 

production region, and Texas is located in the Southern Plain region (Lubowski et al., 2006). 

The Economic Research Service conducts land- use inventories based on available land-use 

data obtained from surveys conducted both by the Economic Research Service and predecessor 

agencies. Figure 4-27 illustrates the dominant land-use patterns in the counties and parishes that 

comprise the BOEM-identified EIAs.

Coastal land loss resulting from erosion, subsidence, and coastal storms is one of the more 

significant cumulative impacts for land use and coastal infrastructure. The Gulf Coast region has 

been experiencing land loss in varying degrees from state to state, especially in coastal Louisiana. 

Figure 4-28 shows the amount of land that coastal Louisiana has lost from 1932 to 2010. Figures 

4-29 and 4-30 illustrate scientists’ projections for future land loss in Louisiana. The moderate 

scenario assumes more mitigating measures, and the less optimistic scenario shows the projected 
4-388 Gulf of Mexico Multisale EIS

impact if extensive mitigating measures are not instituted. Overlaid on all three of these figures are 

the locations of existing OCS oil- and gas-related infrastructure. As evident from these visual 

depictions, coastal land loss is one of the greatest threats to the stability and future of OCS oil- and 

gas-related infrastructure, producing a major negative impact to those facilities located close to 

areas vulnerable to land loss.

Second only to coastal land loss as a major cumulative impact on land use and coastal 

infrastructure are the regular changes in economic trends on the regional, national, and global 

levels. Micro-economic and macro-economic shifts in demand, investment opportunities, and 

commodity prices all affect the course of business in the oil and gas industry and the regional 

economies and communities in ways that are not always in tandem. For example, the drop in the 

price of oil from the end of 2014 through 2015 kept the price of gas down, which is good for people 

and businesses that drive cars and trucks to travel. However, the downturn has also led to many 

layoffs in the oil and gas industry (Larino, 2015; Stickney, 2015; and Strauss, 2015). An economic 

Gordian knot best explains the complex relationship between the industry, society at large, and the 

resources of land use and coastal infrastructure, which reside at the core of this intricate system of 

effects and counter-effects. 

 Figure 4-28. Historical Land Loss in Louisiana, 1932-2010.
Description of the Affected Environment and Impact Analysis 4-389 

Figure 4-29. Moderate Scenario: Projected Land Loss in Louisiana.

Figure 4-30. Less Optimistic Scenario: Projected Land Loss in Louisiana.
4-390 Gulf of Mexico Multisale EIS

Incomplete or Unavailable Information

BOEM has identified incomplete information regarding the potential impacts of coastal land 

loss on land use and coastal infrastructure. This incomplete information may be relevant to adverse 

impacts because it is not completely known how current subsidence and erosion is affecting industry 

or what plans industry is making to mitigate current or future impacts. Because there are hundreds 

of large and small property-owning businesses spread across the coastal zone, which directly and 

indirectly support the offshore petroleum industry, there is no practical way to identify these 

properties and estimate possibilities of losses due to subsidence and erosion. BOEM has proposed 

a study that would attempt to evaluate these potential impacts by surveying industry on current 

impacts and potential adaptation strategies; however, as of the publication of this Multisale 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 

Multisale EIS.

BOEM used reasonably accepted scientific methodologies to extrapolate from existing 

information on dredged material used to mitigate for land loss in completing its analysis and 

formulating the conclusions presented here. For example, in the case of coastal ports, dredged 

material from navigation slips are used to fill in property and mitigation habitat areas for wildlife and 

to act as a barrier to protect ports from storm surges (Volz, 2013). This example shows that, 

although BOEM does not possess a complete understanding of what industrial infrastructure 

improvements may occur, such as mitigation for land loss, industry would most likely mitigate as 

necessary to protect existing and growing infrastructure. Like any industrial infrastructure 

improvements, future adaptations would 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. Therefore, BOEM has determined that the information is not essential to a 

reasoned choice among alternatives. BOEM continues to monitor industry and its infrastructure 

footprint over time to document short- and long-term impacts of continued land loss. For a more 

detailed discussion on deltaic land loss, refer to Chapter 4.3.2 (Coastal Barrier Beaches and 

Associated Dunes.)

4.14.1.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Oil and gas exploration, production, and development activities on the OCS are supported by 

an expansive onshore network of coastal infrastructure that includes hundreds of large and small 

companies. Land use in the Gulf Coast analysis region covers a broad spectrum from rural to 

metropolitan land uses, ranging across 133 counties and parishes from the southern tip of Texas 

north along the Texas coastal plain and looping around the Gulf Coast through Louisiana, 

Mississippi, Alabama, and Florida, all the way southward to Key West in Monroe County, Florida. 

The impact-producing factors for land use and coastal infrastructure would range from negligible to 

minor because oil- and gas-related coastal infrastructure is a mature and extensive system, 

resulting from long-term industry trends, and it is not subject to rapid fluctuations. For example, a 

small-scale expansion of a gas-processing plant would be a negligible impact because of the small 
Description of the Affected Environment and Impact Analysis 4-391

size of the project, the temporary disruptions caused by increased construction traffic, and the 

geographically small area affected. If the expansion project was larger, lasting a few weeks and 

affecting a larger geographic area, then the impact would be minor. If the gas-processing plant 

project was larger in scale, causing disruptions because of construction activities that last up to 

1 year, then the impact would be moderate. Activities related to a proposed action are expected to 

minimally affect the current land use of the analysis area because most subareas have strong 

industrial bases and designated industrial parks with existing infrastructure and facilities that have 

sufficient capacity to accommodate future growth. BOEM’s scenario projections call for the new 

construction of 0-1 new gas processing facility and 0-1 new pipeline landfall to result from a 

proposed lease sale over the analysis period. Increases in demand for services at other facilities 

would be met by current excess capacity or expansions at current facilities. These activities, along 

with noncatastrophic accidental events, are reasonably foreseeable.

The impacts of reasonably foreseeable accidental events, such as oil spills, chemical and 

drilling fluid spills, vessel collisions, and spill-response activities are expected to be negligible to 

moderate depending on the location, size, and duration of the event. Potential impacts could 

include damages to private and public lands, personal injury, damages to collateral property 

(moveable property such as vehicles and boats), and economic damages from the disruption of 

business. For example, if an oil spill is very small (not measurable) in size, located in a small 

geographic and remote area, and dissipates quickly, its impact would be negligible. If a spill is 

measurable, covers a larger geographic area, and lasts a few days to a month, then its impact would 

be minor. If a spill occurs in a highly populated area, is larger in quantity, and the response and 

cleanup last over a month and up to a year with either waterborne commerce affected and/or land 

transportation affected, then the impact would be moderate. 

In regard to cumulative impacts, activities relating to the OCS Oil and Gas Program and 

State oil and gas production are expected to minimally affect the current land use of the analysis

area because most subareas have strong industrial bases and designated industrial parks to

accommodate future growth. The incremental contribution of a proposed lease sale to the 

cumulative impacts on land use and coastal infrastructure are expected to be minor because the 

impacts of one lease sale are minimal when compared with the combination of all past, present, 

and future lease sales. Non-OCS oil- and gas-related impact-producing factors provide a very large 

contribution to the cumulative impacts on land use and coastal infrastructure, but there is only a

minor incremental contribution of a proposed lease sale and OCS Oil and Gas Program to all 

cumulative impacts. The cumulative impacts of non-OCS oil- and gas-related factors on land use 

and coastal infrastructure could range from negligible to major depending on the specific situation, 

whether the impacts are measurable, how impacts are measured, how long they would last, the size 

of the affected area, and the viewpoints of the various people that may be involved.
4-392 Gulf of Mexico Multisale EIS

4.14.1.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Impacts for land use and coastal infrastructure are directly related to the level of OCS oiland gas-related activities in the Gulf of Mexico. Alternative B would result in less OCS oil- and gasrelated activities than Alternative A because the WPA (approximately 23 million ac) would not be 

available for leasing. Alternative A includes all three planning areas of the GOM (i.e., the WPA, 

CPA, and EPA). Alternative B includes the CPA and EPA, and excludes the WPA. Therefore, 

Alternative B would produce proportionately smaller OCS oil- and gas-related activities than 

Alternative A, and the impacts of Alternative B would be proportionately less than Alternative A but 

greater than Alternative C, as described below.

4.14.1.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Impacts for land use and coastal infrastructure are directly related to the level of OCS 

oil- and gas-related activities in the Gulf of Mexico. Alternative C would result in less OCS oil- and 

gas-related activities than Alternative A or B because the CPA and EPA (approximately 48 million 

ac) would not be available leasing. Alternative A includes the WPA, CPA, and EPA, and Alternative 

B include the CPA and EPA. In contrast, Alternative C includes only the WPA. Therefore, 

Alternative C would produce proportionately smaller OCS oil- and gas-related activities than 

Alternative A and B, and the impacts of Alternative C would be proportionately less than either 

Alternative A or B.

4.14.1.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Impacts for land use and coastal infrastructure are directly related to the level of OCS oiland gas-related activities in the Gulf of Mexico. Alternative D would have minimal impact on social 

factors because there are so few available unleased blocks subject to the Topographic Features, 

Live Bottom (Pinnacle Trend), and Blocks South of Baldwin County, Alabama, Stipulations. The 

difference between Alternatives A, B, and C, with and without the exclusionary stipulations, is 

negligible for land use and coastal infrastructure. The impacts under Alternative D would not be 

much different and likely not even be measurable when compared with the other alternatives. To the 

extent that Alternative D would generate less OCS oil- and gas-related activities due to the reduced 

number of blocks available for lease, the impacts of Alternative D would be slightly less than 

Alternative A, B or C, but this difference would likely be indiscernible.

4.14.1.2.5 Alternative E—No Action

Alternative E would result in no lease sale and, thus, no direct impacts as a result of a 

proposed lease sale and no incremental contribution of impacts to land use and coastal 

infrastructure beyond a temporary negative economic impact for the oil and gas industry. However, 

activities and impacts from activities related to past OCS oil and gas lease sales would continue. 
Description of the Affected Environment and Impact Analysis 4-393

Since a single lease sale produces minimal impact, it would take the cancellation of several lease 

sales before a substantial impact would be experienced.

4.14.2 Economic Factors

This chapter discusses the affected environment, routine activities, accidental events, and 

cumulative impacts to economic factors that would arise from the alternatives. Many of the 

economic impacts of the alternatives would be beneficial, and these impacts are stated in terms of 

standard measures of economic activity. The negative impacts are measured in terms of the 

severity, duration, and geographical extent of impacts. In particular, the impact-level measures are 

listed below.

Impact-Level Definitions

In this chapter (and in the analyses of the alternatives) the impact measures are defined in 

terms of the intensity, duration, and geographical extent of the impacts to the human uses of 

recreational resources along the Gulf Coast. 

• Beneficial – Impacts would be stated in levels and percentages of employment 

(number of jobs), labor income (wages, benefits, and sole-proprietor income), 

and/or value-added (contribution to gross regional product).

• Negligible – Little or no detectable impact.

• Minor – Impacts are detectable but less than severe.

• Moderate – Impacts are severe but are short-term and/or not extensive.

• Major – Impacts are long-term, extensive, and severe.

4.14.2.1 Description of the Affected Environment

Economic factors are factors that explain and quantify the human behaviors that determine 

the positive and negative impacts from the alternatives. The following sections discuss the overall 

economies that could be impacted by the alternatives, as well as provide specific information 

regarding the offshore oil and gas industry.

Economic Impact Areas

Offshore oil and gas activities affect various onshore areas because of the various industries 

involved and because of the complex supply chains for these industries. Many of these impacts 

occur in counties and parishes along the Gulf of Mexico region. BOEM aggregates 133 GOM 

counties and parishes into 23 EIAs based on economic and demographic similarities among 

counties/parishes (Fannin and Varnado, 2015); Figure 4-27 is a map of these EIAs. Much of the 

analysis below focuses on these EIAs since many of the positive and negative impacts of the 

alternatives would be concentrated in these EIAs. These EIAs also serve as consistent units for 

which to present various economic and demographic data.
4-394 Gulf of Mexico Multisale EIS

Economic and Demographic Data

Woods & Poole Economics, Inc. (2015) provides county-level economic and demographic 

data for prior years, as well as forecasts of these data through 2050. Table 4-27 aggregates the 

Woods & Poole data by EIA and presents each EIA’s population, employment, gross regional 

product, labor income, median age, male percentage, and race composition. The largest EIAs 

(presented in descending order of gross regional product) are TX-3 (which includes Houston and 

Galveston), FL-5 (which includes Tampa), LA-6 (which includes New Orleans), LA-5 (which includes 

Baton Rouge), FL-6, and TX-1. The smallest EIAs (presented in ascending order of gross regional 

product) are MS-2, TX-6, AL-2, LA-2, and TX-4. The forecasts from Woods & Poole Economics, Inc. 

(2015) for future years are presented in the cumulative analysis (Chapter 4.14.2.2). Kaplan et al. 

(2011) presents additional economic and demographic data for certain GOM regions that are 

important to the offshore oil and gas industry.

Table 4-27. Economic and Demographic Information for BOEM's Economic Impact Areas in 2015.

Economic Variables Demographic Variables

EIA Population Employment Gross Regional 

Product1

Labor 

Income

Median 

Age Male % White Black Hispanic Native American Asian

Texas

TX-1 1,713,140 752,177 45,961,422 26,189,354 32.2 49.0% 7.4% 0.5% 91.1% 0.1% 0.9%

TX-2 757,829 440,230 40,665,099 21,121,438 39.3 50.0% 37.8% 4.9% 55.4% 0.3% 1.6%

TX-3 6,340,375 3,897,727 433,804,883 268,244,910 35.9 49.8% 37.1% 17.1% 37.5% 0.3% 7.9%

TX-4 163,193 59,934 4,119,292 2,059,513 40.2 49.5% 75.9% 9.0% 13.9% 0.4% 0.7%

TX-5 374,402 205,831 18,218,742 10,695,487 37.1 50.9% 53.7% 25.9% 17.0% 0.4% 3.0%

TX-6 50,558 22,415 1,388,043 684,253 41.6 50.0% 74.6% 18.4% 5.8% 0.5% 0.7%

Louisiana

LA-1 204,559 119,065 10,819,182 5,701,097 38.5 48.8% 70.2% 24.9% 3.0% 0.5% 1.4%

LA-2 89,805 41,414 4,077,567 2,040,359 34.1 52.0% 75.1% 14.5% 7.2% 1.3% 1.8%

LA-3 588,935 337,248 34,334,083 16,300,997 36.7 49.2% 68.5% 26.7% 3.1% 0.5% 1.2%

LA-4 364,662 219,030 23,652,206 11,941,630 37.6 49.3% 67.4% 23.4% 4.6% 3.0% 1.6%

LA-5 858,991 533,746 49,605,913 26,421,022 37.3 48.7% 56.6% 37.0% 4.0% 0.3% 2.2%

LA-6 934,399 612,228 59,338,051 32,291,523 36.3 48.5% 46.3% 39.8% 9.9% 0.4% 3.7%

LA-7 425,178 207,007 16,064,830 8,610,839 38.4 48.7% 73.8% 19.9% 4.6% 0.4% 1.2%

Mississippi

MS-1 442,571 230,577 16,142,025 10,142,320 39.2 49.5% 71.4% 20.6% 5.1% 0.5% 2.5%

MS-2 68,605 21,814 1,132,099 675,920 38.2 52.1% 79.7% 18.0% 1.6% 0.4% 0.3%

Alabama

AL-1 620,990 338,439 22,529,209 13,682,033 40.0 48.2% 66.7% 27.3% 3.4% 0.9% 1.8%

AL-2 115,636 51,498 3,406,314 2,053,406 42.2 49.2% 57.7% 37.5% 1.6% 2.8% 0.4%
Description of the Affected Environment and Impact Analysis 4-395

Economic Variables Demographic Variables

EIA Population Employment Gross Regional 

Product1

Labor 

Income

Median 

Age Male % White Black Hispanic Native 

American Asian

Florida

FL-1 913,655 499,506 34,545,257 21,061,882 39.2 50.4% 75.8% 14.1% 6.2% 0.8% 3.1%

FL-2 513,271 273,299 18,167,329 11,079,024 40.4 50.8% 61.9% 29.5% 5.9% 0.5% 2.2%

FL-3 237,107 89,044 5,422,707 3,259,404 41.3 54.5% 70.5% 22.0% 6.3% 0.5% 0.8%

FL-4 1,436,702 604,746 36,362,418 22,058,081 48.6 48.7% 75.7% 11.2% 10.2% 0.3% 2.5%

FL-5 4,151,943 2,229,968 164,060,192 100,460,406 45.4 48.6% 67.0% 11.9% 17.6% 0.3% 3.2%

FL-6 1,495,975 752,134 47,563,571 29,203,481 45.5 49.8% 68.4% 7.9% 21.8% 0.3% 1.5%

EIA = Economic Impact Area.

1 Gross Regional Product and labor income are presented in thousands of dollars.

Source: Woods & Poole Economics, Inc., 2015.

Offshore Oil and Gas Industry

The offshore energy industry in the Gulf of Mexico extracts oil, natural gas, and natural gas 

liquids (NGLs), which are then processed and transported for use in various activities, including 

transportation, electricity generation, space heating, and chemical manufacturing. Extraction of oil, 

natural gas, and natural gas liquids entails spending on various processes, including G&G 

surveying, drilling, platform fabrication, shipbuilding, and various support services. Spending on 

these processes supports businesses further along supply chains and supports spending by 

workers. Quest Offshore Resources, Inc. (2011) provides an overview of the spending impacts of 

the offshore oil and gas industry in the Gulf of Mexico. This report estimates that $26.9 billion in 

capital and operating expenditures supported $29.1 billion in U.S. gross domestic product in 2009. 

Kaiser et al. (2013) provide background information on the drilling and rig construction markets; 

Eastern Research Group, Inc. (2011) provides background information on the oil services contract 

industry; and Priest and Lajaunie (2014) and Austin et al. (2014a) present background information 

on the shipbuilding and fabrication industries.

The offshore energy industry has been adapting to recent declines in energy prices. Lower 

energy prices have caused slowdowns in offshore drilling activities (Beaubouef, 2015) and rig 

construction (Odell, 2015). However, offshore oil and gas production is generally slower to respond 

to changes in energy prices since offshore developments take years to be designed, approved, and 

developed. Once a project is producing, it is often most profitable to maintain production as long as 

the revenues received are above the marginal costs of production. Indeed, GOM offshore oil 

production is forecast to increase from an average of 1.54 MMbbl/day in 2015 to 1.63 MMbbl/day in 

2016 and to 1.79 MMbbl/day in 2017 (USDOE, Energy Information Administration, 2016a). This 

production increase reflects the contributions of 14 Gulf of Mexico projects that are expected to 

come online in 2016 and 2017 (USDOE, Energy Information Administration, 2016b).
4-396 Gulf of Mexico Multisale EIS

Office of Natural Resources Revenue Data

The U.S. Department of the Interior’s Office of Natural Resources Revenue collects various 

data regarding offshore oil and gas activities. Table 4-28 presents data regarding sales volumes, 

sales values, and government revenues received from Federal offshore energy activities in the Gulf 

of Mexico (USDOI, Office of Natural Resources Revenue, 2015). Government revenues are 

generated from offshore oil and gas activities through bonus bids, rental payments, and royalty 

payments. Bonus bids are received shortly after a lease sale, rental payments occur during the 

nonproducing phase of a lease, and royalties are paid as a percentage of oil and gas output from a 

lease. BOEM’s “Fair Market Value” webpage describes the rental rates, royalty rates, and other 

terms associated with Gulf of Mexico leases (USDOI, BOEM, 2015d). Some offshore oil and gas 

activities are subject to partial or full royalty exemptions. BOEM’s “Royalty Relief Information” 

webpage provides more information regarding BOEM’s royalty relief programs (USDOI, BOEM, 

2015e).

Panel A of Table 4-28 presents annual data regarding the quantities of royalty-bearing and 

nonroyalty-bearing sales volumes of natural gas, 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 almost 36 MMbbl in FY 2013 to 40 MMbbl in FY 2014, while sales volumes on nonroyaltybearing NGLs decreased from 9.1 MMbbl in FY 2013 to 7.4 MMbbl in FY 2014. Sales volumes of 

royalty-bearing oil increased from 358 MMbbl in FY 2013 to 396 MMbbl in FY 2014, while sales 

volumes on nonroyalty-bearing oil decreased from 100 MMbbl in FY 2013 to 87 MMbbl in FY 2014. 

Panel B of Table 4-31 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 4-31 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.
Description of the Affected Environment and Impact Analysis 4-397

Table 4-28. Sales Volumes, Sales Values, and Revenues.

Panel A: Sales Volumes

FY 2008 2009 2010 2011 2012 2013 2014

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 (nonroyalty) (mcf) 316,986,987 461,373,909 371,665,155 297,608,514 241,687,280 232,010,830 157,147,262

NGL (royalty) 

(bbl) 48,691,691 41,495,664 48,461,861 42,672,187 37,429,317 35,984,532 40,008,495

NGL (nonroyalty) (bbl) 3,857,382 3,701,216 9,158,031 9,229,184 7,247,838 9,113,729 7,433,072

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 (nonroyalty) (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

FY 2008 2009 2010 2011 2012 2013 2014

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 ($) 423,743 173,955 86,350 60,125 48,228 66,780 41,563

Total ($) 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

FY 2008 2009 2010 2011 2012 2013 2014

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 ($) 3,325,433 -29,904,061 46,809,265 3,951,382 5,045,519 34,753,295 43,014,645

Total ($) 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

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 ($) 423,743 173,955 86,350 60,125 48,228 66,780 41,563

Total ($) 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

(1) This table presents the sales volumes, sales values, and revenues received based on offshore oil and gas activities in the Gulf of 

Mexico.

(2) Data in this table refer to the years in which sales occurred (not to the years in which government revenues were received).

Source: USDOI, Office of Natural Resources Revenue, 2015.
4-398 Gulf of Mexico Multisale EIS

4.14.2.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

economic factors that would arise from projected activities from a single lease sale are analyzed in 

this chapter. While there are some differences in the amount of activities associated with the 

alternatives, many of the impacts associated with the alternatives are similar. Therefore, this 

chapter describes the impacts that are expected to apply to all alternatives, while any deviations 

from these impact conclusions are discussed in Chapters 4.14.2.2.1-4.14.2.2.6. 

For each alternative, the numerical estimates are presented for two scenarios for oil and gas 

development:

(1) Low: A scenario that corresponds to low amounts of offshore oil and gas 

activities, which could arise due to low oil and gas prices or other unfavorable 

economic conditions. This scenario also assumes that oil and gas leasing 

activities would be spread over two lease sales in a given year.

(2) High: A scenario that corresponds to high amounts of offshore oil and gas 

activities, which could arise due to high oil and gas prices or other favorable 

economic conditions. This scenario also assumes that oil and gas leasing 

activities would be spread over two lease sales in a given year.

It is also possible that industry could focus their leasing activities in a particular lease sale for 

unique circumstances rather than activity being spread over two lease sales in a given year. If this 

would occur, the economic impacts would be approximately double the impacts presented here. 

However, this is unlikely to occur, particularly as industry adjusts to the pattern of two lease sales 

per year.

Routine Activities

Routine activities arising from a proposed action would have various economic impacts. 

First, extraction of oil, NGLs, and natural gas generate expenditures on various goods and services. 

Routine activities could also generate corporate profits and government revenues, as well as have 

impacts on the overall energy market. Finally, a proposed action would have negative impacts 

(discussed below) that would partially offset the positive impacts. It is important to note that a 

proposed action occurs in the context of an expansive existing offshore oil and gas industry. 

Therefore, the various impacts (discussed below) should be interpreted as the extent to which the 

alternatives contribute to the impacts of the existing offshore oil and gas existing industry.

Expenditure Impacts

A proposed action would have economic impacts on a variety of businesses along the OCS 

industry’s supply chain. For example, a proposed action would directly affect firms that drill wells, 

manufacture equipment, construct pipelines, and service OCS oil- and gas-related activities. The 

OCS oil- and gas-related activities would also impact the suppliers to those firms, as well as firms 
Description of the Affected Environment and Impact Analysis 4-399

that depend on consumer spending of oil and gas industry workers. In order to estimate these 

impacts, BOEM has developed MAG-PLAN, which is a two-stage economic model. The first stage 

estimates the levels of spending in various industries that arise from a particular scenario for oil and 

gas exploration and development. The second stage estimates the employment, income, and value 

added impacts that result from oil and gas industry spending along the Gulf Coast. The OCS 

industry’s spending would support activities further down the supply chain; these are referred to as 

“indirect” impacts. In addition, the incomes of employees along the OCS industry’s supply chain 

would support consumer spending throughout the economy; these are referred to as “induced” 

impacts. These indirect and induced impacts are estimated using the economic modeling software 

and data system IMPLAN. In particular, MAG-PLAN uses IMPLAN “multipliers” to compute how 

direct OCS spending translates into various direct, indirect, and induced economic impacts. 

MAG-PLAN results for the various scenarios are presented in Chapters 4.14.2.2.1-4.14.2.2.5. 

Government Revenue Impacts

A proposed action would generate government revenues through bonus bids, rental 

payments, and royalty payments. Revenue forecasts for the alternatives are discussed in Chapters 

4.14.2.2.1-4.14.2.2.5. The impacts generated by these revenues depend on where and how the 

revenues are used. Historically, most revenues have accrued directly to the Federal Treasury. 

Although it is not possible to trace Federal spending to specific revenue streams, it is reasonable to 

assume that Federal OCS revenues would be spent in approximately the same proportions as 

overall Federal spending. This implies that the Federal revenue impacts of OCS oil- and gas-related 

activities would be fairly widespread, and thus not overly concentrated in BOEM’s economic impact 

areas. Historically, modest portions of OCS revenues beyond those implicit in normal Federal 

spending have been allocated to the Gulf Coast States, including 8(g) revenues (which arise due to 

leasing with 3 mi [5 km] of State waters), the Coastal Impact Assistance Program, and Phase 1 

revenue sharing arising from the Gulf of Mexico Energy Security Act of 2006 (GOMESA). Phase 2 

of GOMESA revenue sharing, which will begin in Fiscal Year 2017, will expand revenue sharing with 

Texas, Louisiana, Mississippi, and Alabama. In particular, Phase 2 of GOMESA calls for 

37.5 percent of qualified revenues to be disbursed to the Gulf Coast States and their political 

subdivisions, and 12.5 percent of revenues to be disbursed to the Land and Water Conservation 

Fund. Phase 2 revenue sharing will be subject to a $500 million cap through 2055 (USDOI, BOEM, 

2015d). Phase 2 of GOMESA may increase the beneficial impacts to BOEM’s economic impact 

areas arising from a proposed action, although only if the revenues occur in a year in which the cap 

was not reached by revenues arising from other lease sales. The economic impacts of the various 

revenue disbursements would depend on how and where the money is spent. The OCS oil- and 

gas-related activities can also induce government revenues arising from taxes on economic activities 

(such as taxes on profits and dividends). The USDOI (2015b) provides methodologies for estimating 

the scales and distributions of revenue impacts of OCS oil- and gas-related activities. This report 

estimates that revenue impacts accounted for 26 percent of total value-added impacts in the United 

States in 2014. This percentage is forecast to remain roughly similar in future years, although it 

could vary based on oil prices and the geographic distributions of impacts would change because of 

GOMESA revenues.
4-400 Gulf of Mexico Multisale EIS

Profit Impacts

A proposed action could also generate profits to firms along the OCS supply chain. 

Corporate profits can be distributed to stockholders as dividends or retained by firms for future 

spending on goods and services. Higher profits can also increase stock prices, which would 

increase the wealth of stockholders. Since stocks of most energy firms can be held by people from 

anywhere in the world, the wealth and dividend impacts would be fairly widespread and, thus, not 

overly concentrated in BOEM’s economic impact areas. Similarly, it is difficult to trace specific 

spending by firms to increases in corporate profits, although these impacts are also likely to be 

widespread. The USDOI (2015b) estimates that approximately 25 percent of total value-added 

benefit to the United States from the OCS Program arises due to corporate profits, and this 

percentage could vary slightly during the timeframe of a proposed action, given changes in oil prices 

and other factors.

Market Impacts

The oil, natural gas, and NGLs produced due to a proposed action would meet the demands 

of end users of those products. Increased energy supply would put downward pressure on energy 

prices, although the small scale of a proposed action relative to the overall energy market would 

make these price effects minimal. The OCS crude oil production typically has different quality 

measures (such as API gravity and sulfur content) than crude oil from other sources and flows 

through pipelines already in place, which can enhance the relative value of OCS crude to nearby 

refiners designed to process OCS-type crude oil. A proposed action can also contribute to U.S. 

policy goals of energy independence and security. Again, these impacts would be small due to the 

small scale of a proposed action. 

Adverse Impacts

A proposed action could negatively affect various resources, as described in the other 

chapters of this Multisale EIS. The corresponding negative economic impacts are also discussed in 

their respective chapters. For example, the OCS Program could cause negative impacts to 

recreational fishing, commercial fisheries, recreational resources, land use and coastal 

infrastructure, and social factors. Industrial Economics (2012) provides information regarding the 

Offshore Environmental Cost Model, which incorporates methodologies for quantifying the adverse 

impacts to various resources. However, these adverse impacts are likely to be minor because of 

the small scale of a proposed action.

In summary, a proposed action would have various beneficial impacts, such as impacts from 

expenditures, government revenues, corporate profits, and market adjustments. A proposed action 

would also lead to minor adverse impacts that would partially offset the beneficial impacts.

Accidental Events

Accidental events, such as oil spills, chemical spills, and vessel collisions, can have various 

impacts on local economies. The most direct impacts are felt in industries that depend on resources 
Description of the Affected Environment and Impact Analysis 4-401

that are damaged or rendered unusable for a period of time. For example, beach recreation, 

recreational fishing, and commercial fishing would be vulnerable if beach or fish resources were 

damaged due to an accidental event. However, since accidental events arising from a proposed 

action would likely be small, the impacts to economic factors would likely be negligible or minor. 

More information on the impacts of accidental events on these individual resources can be found in 

Chapters 4.10, 4.11, and 4.12. An oil spill could also impact important transportation routes or 

impact the operations of port facilities. However, the likelihood of a single oil spill shutting down an 

entire waterway or port facility is quite low.

The other economic impacts of an accidental event would be determined by indirect actions 

or events that occur along with an oil spill. For example, an oil spill could lead to decreased levels of 

oil and gas industry operations. These impacts would be most felt in coastal Louisiana and Texas 

since these are the primary locations where OCS oil- and gas-related employment is concentrated. 

The direct impacts of an oil spill on a particular industry would also ripple through that industry’s 

supply chain; consumer spending by employees of these firms would also have impacts to the 

broader economy. Decreased levels of offshore oil and gas activities could also impact corporate 

profits and the revenue streams of the various levels of government in the impacted areas. Finally, 

the response and cleanup operations following an oil spill can have impacts on local economies. For 

example, compensation for damages could partially mitigate the economic impacts of an accidental 

event. The influx of response workers to local areas can have positive economic impacts, although 

it can also cause disruptions to the normal functioning of local economies. In addition, the people 

and equipment that are dedicated to oil-spill response efforts may be diverted from some existing 

services (such as hospitals, firefighting capability, and emergency services) available to local 

residents. These indirect impacts would be negligible for most spills expected to arise from a 

proposed action, although they could be minor in unique circumstances.

The Deepwater Horizon oil spill provides some insights into the impacts of oil spills, although 

an oil spill of the scale of the Deepwater Horizon is not part of a proposed action and not reasonably 

foreseeable; the impacts of catastrophic spills are discussed in Catastrophic Spill Event Analysis

white paper (USDOI, BOEM, 2016c). Austin et al. (2014b and 2014c) are two volumes of a recently 

completed study of the economic and social impacts of the Deepwater Horizon oil spill. This study 

employed an ethnographic methodology that entailed analyzing data sources, examining various 

sources of descriptive information, and conducting field interviews with people in Louisiana, 

Mississippi, and Alabama. This study documents the complex and varied impacts of the Deepwater 

Horizon oil spill during the 20 months subsequent to the spill. This study found that the impacts of 

the spill on a particular community depended on a number of factors, such as its proximity to the 

spill, its economic structure, its social and political dynamics, its organizational structure for dealing 

with disasters, and its ability to adapt to the structures of the oil cleanup and damage claims 

processes.

Overall, the economic impacts from accidental events likely to arise from a proposed action 

would likely be negligible or minor because any oil spills would likely be small.
4-402 Gulf of Mexico Multisale EIS

Cumulative Impacts

OCS Oil- and Gas-Related Impacts

A proposed action would contribute to the economic impacts arising from the overall OCS 

Program (which includes all past, present, and future lease sales). The OCS Program would have 

economic impacts on a variety of firms along the OCS industry’s supply chain. BOEM uses the 

model MAG-PLAN (described above) to estimate the impacts of offshore oil and gas industry 

expenditures. MAG-PLAN’s estimates of the total employment, labor income, and value-added 

impacts for the low and high cumulative scenarios are presented in Tables 4-29 and 4-30. These 

tables present the average values (over 50 years), peak values, and percent of peak values relative 

to total employment, labor income, and value-added in each EIA. In the low scenario, the OCS 

Program would support a peak of 110,000 jobs, $8 billion in labor income, and $14 billion in valueadded benefits throughout the United States. Most of these impacts would occur in the Gulf of 

Mexico region, particularly in coastal Texas and Louisiana. The EIAs that would experience the 

highest economic impacts are TX-3, TX-2, LA-3, LA-4, LA-6, MS-1, and AL-1. In the high scenario, 

a proposed action would support a peak of 250,000 jobs, $15 billion in labor income, and $24 billion 

in value-added. The geographic distributions of impacts would be similar to those of the low 

scenario.

The overall OCS Program (which refers to all past, present, and future lease sales; refer to 

Chapter 3.3.1 for more information) generates government revenues through bonus bids, rental 

payments, and royalty payments (described above). BOEM estimates the revenues associated with 

the OCS Program under the low- and high-case cumulative scenarios for the following time horizons: 

bonus bids (26 years); rental payments (35 years); and royalty payments (70 years). In the low-case 

scenario, the OCS Program would generate approximately $9.4 billion in bonus bids, $2.6 billion in 

total rental payments (with an annual peak of $151 million), and $132 billion in royalty payments 

(with an annual peak of $3.5 billion). In the high-case scenario, the OCS Program would generate 

approximately $17.8 billion in bonus bids, $4.8 billion in total rental payments (with an annual peak 

of $175 million), and $922.9 billion in total royalty payments (with an annual peak of $18.8 billion). 

The geographic distributions of impacts from these revenues would correspond to those described 

above.

A proposed action would also contribute to the corporate profit impacts, market impacts, 

adverse impacts from routine activities, and adverse impacts from accidental events that would arise 

from the overall OCS Program. The impacts arising from the overall OCS Program would be directly 

proportional to the amount of activity (discussed above). The incremental contribution of any of the 

alternatives relative to the overall OCS Program would be minimal.
Description of the Affected Environment and Impact Analysis 4-403

Table 4-29. Cumulative Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Texas

TX-1 1,340 2,470 0.0% 67,000 127,000 0.0% 101,000 190,000 0.0%

TX-2 3,360 6,310 0.1% 204,000 378,000 0.1% 378,000 679,000 0.0%

TX-3 13,890 26,150 0.1% 1,276,000 2,437,000 0.1% 2,433,000 4,343,000 0.0%

TX-4 100 190 0.0% 6,000 12,000 0.0% 13,000 23,000 0.0%

TX-5 370 670 0.0% 27,000 48,000 0.0% 76,000 122,000 0.0%

TX-6 20 30 0.0% 1,000 2,000 0.0% 2,000 3,000 0.0%

All Texas EIAs 19,080 35,830 – 1,582,000 3,002,000 – 3,002,000 5,360,000 –

Rest of Texas 2,920 5,700 – 204,000 409,000 – 401,000 741,000 –

Texas Total 22,000 41,530 – 1,786,000 3,411,000 – 3,404,000 6,098,000 –

Louisiana

LA-1 1,040 1,970 0.2% 74,000 141,000 0.2% 111,000 210,000 0.2%

LA-2 40 80 0.0% 2,000 3,000 0.0% 3,000 6,000 0.0%

LA-3 2,810 5,150 0.2% 147,000 266,000 0.1% 277,000 485,000 0.1%

LA-4 3,560 6,850 0.3% 247,000 476,000 0.3% 400,000 752,000 0.2%

LA-5 1,100 2,190 0.1% 57,000 115,000 0.0% 94,000 183,000 0.0%

LA-6 3,290 6,380 0.1% 198,000 383,000 0.1% 308,000 579,000 0.1%

LA-7 510 1,000 0.1% 26,000 51,000 0.0% 44,000 83,000 0.0%

All Louisiana EIAs 12,350 23,510 – 751,000 1,428,000 – 1,238,000 2,293,000 –

Rest of Louisiana 1,850 3,570 – 105,000 206,000 – 212,000 393,000 –

Louisiana Total 14,200 27,060 – 856,000 1,634,000 – 1,450,000 2,681,000 –

Mississippi

MS-1 2,460 5,000 0.3% 129,000 264,000 0.3% 195,000 392,000 0.3%

MS-2 120 240 0.2% 4,000 8,000 0.1% 7,000 14,000 0.1%

All Mississippi EIAs 2,580 5,230 – 133,000 272,000 – 202,000 406,000 –

Rest of Mississippi 2,240 4,350 – 120,000 237,000 – 223,000 413,000 –

Mississippi Total 4,820 9,590 – 252,000 509,000 – 425,000 819,000 –

Alabama

AL-1 2,810 5,900 0.2% 135,000 294,000 0.2% 227,000 473,000 0.2%

AL-2 220 450 0.1% 9,000 20,000 0.1% 18,000 35,000 0.1%

All Alabama EIAs 3,020 6,350 – 144,000 314,000 – 244,000 508,000 –

Rest of Alabama 1,760 3,540 – 104,000 218,000 – 205,000 386,000 –

Alabama Total 4,780 9,890 – 248,000 532,000 – 450,000 892,000 –

Florida

FL-1 290 680 0.0% 21,000 53,000 0.0% 40,000 90,000 0.0%

FL-2 10 20 0.0% 0 1,000 0.0% 1,000 2,000 0.0%

FL-3 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-4 50 110 0.0% 3,000 7,000 0.0% 7,000 14,000 0.0%

FL-5 20 50 0.0% 1,000 3,000 0.0% 3,000 5,000 0.0%

FL-6 0 10 0.0% 0 1,000 0.0% 1,000 1,000 0.0%

All Florida EIAs 380 870 – 26,000 64,000 – 52,000 112,000 –

Rest of Florida 1,700 3,310 – 107,000 209,000 – 202,000 370,000 –

Florida Total 2,080 4,180 – 132,000 273,000 – 254,000 477,000 –

All States

All EIAs in All States 37,410 71,780 – 2,635,000 5,080,000 – 4,738,000 8,675,000 –

All Gulf States 47,880 92,250 – 3,275,000 6,359,000 – 5,981,000 10,966,000 –
4-404 Gulf of Mexico Multisale EIS

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

USA

Rest of the United 

States 9,520 20,750 – 726,000 1,650,000 – 1,540,000 3,020,000 – 

Totals

Total Expenditure 

Impacts 57,400 113,000 – 4,000,000 8,009,000 – 7,521,000 13,986,000 – 

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Table 4-30. Cumulative High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Texas

TX-1 90 480 0.0% 4,000 20,000 0.0% 6,000 29,000 0.0%

TX-2 320 1,310 0.1% 17,000 66,000 0.1% 24,000 95,000 0.0%

TX-3 2,170 7,640 0.1% 178,000 617,000 0.1% 246,000 865,000 0.0%

TX-4 10 40 0.0% 1,000 2,000 0.0% 1,000 3,000 0.0%

TX-5 40 140 0.0% 2,000 8,000 0.0% 3,000 12,000 0.0%

TX-6 0 10 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 2,630 9,490 – 201,000 705,000 – 281,000 997,000 –

Rest of Texas 360 1,200 – 22,000 73,000 – 37,000 126,000 –

Texas Total 2,990 10,650 – 223,000 778,000 – 318,000 1,122,000 –

Louisiana

LA-1 160 430 0.2% 11,000 30,000 0.2% 16,000 43,000 0.2%

LA-2 10 20 0.0% 0 1,000 0.0% 0 1,000 0.0%

LA-3 460 1,240 0.2% 23,000 61,000 0.1% 34,000 92,000 0.1%

LA-4 480 1,460 0.3% 31,000 95,000 0.3% 45,000 137,000 0.2%

LA-5 200 590 0.1% 10,000 28,000 0.0% 15,000 43,000 0.0%

LA-6 530 1,540 0.1% 31,000 90,000 0.1% 44,000 125,000 0.1%

LA-7 100 260 0.1% 4,000 12,000 0.0% 6,000 17,000 0.0%

All Louisiana EIAs 1,930 5,470 – 110,000 313,000 – 161,000 454,000 –

Rest of Louisiana 230 730 – 11,000 34,000 – 20,000 65,000 –

Louisiana Total 2,160 6,180 – 121,000 347,000 – 181,000 517,000 –

Mississippi

MS-1 450 1,400 0.3% 20,000 64,000 0.3% 30,000 94,000 0.3%

MS-2 30 70 0.2% 1,000 2,000 0.1% 1,000 3,000 0.1%

All Mississippi EIAs 480 1,460 – 21,000 65,000 – 31,000 97,000 – 

Rest of Mississippi 250 840 – 11,000 39,000 – 19,000 67,000 –

Mississippi Total 730 2,280 – 32,000 103,000 – 50,000 163,000 –

Alabama

AL-1 510 1,650 0.2% 21,000 70,000 0.2% 34,000 115,000 0.2%

AL-2 40 130 0.1% 1,000 5,000 0.1% 3,000 9,000 0.1%

All Alabama EIAs 550 1,780 – 23,000 75,000 – 36,000 124,000 –

Rest of Alabama 200 710 – 10,000 35,000 – 18,000 65,000 –

Alabama Total 760 2,470 – 33,000 110,000 – 54,000 189,000 –
Description of the Affected Environment and Impact Analysis 4-405

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Florida

FL-1 20 150 0.0% 1,000 11,000 0.0% 2,000 18,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 10 20 0.0% 0 1,000 0.0% 1,000 2,000 0.0%

FL-5 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 30 180 – 2,000 12,000 – 3,000 21,000 –

Rest of Florida 220 720 – 12,000 38,000 – 20,000 66,000 –

Florida Total 260 870 – 14,000 48,000 – 24,000 83,000 –

All States

All EIAs in All States 5,630 18,360 – 356,000 1,165,000 – 512,000 1,682,000 – 

All Gulf States 6,900 22,420 – 422,000 1,383,000 – 627,000 2,069,000 –

USA

Rest of the United 

States 1,080 4,680 – 69,000 299,000 – 128,000 564,000 – 

Totals

Total Expenditure 

Impacts 7,980 27,030 – 491,000 1,669,000 – 755,000 2,605,000 – 

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Non-OCS Oil- and Gas-Related Impacts

Woods & Poole Data

Most approaches to analyzing cumulative impacts begin by assembling a list of other likely 

projects and actions that would be included with a proposed action for analysis. However, no such 

list of future projects and actions could be assembled that would be sufficiently current and 

comprehensive to support a cumulative analysis for all 133 of the coastal counties and parishes in 

the analysis area. Instead of an arbitrary assemblage of future possible projects and actions, the 

analysis employs the economic and demographic projections from Woods & Poole Economics, Inc. 

(2015) to define the contributions of other likely projects, actions, and trends to the cumulative case. 

These projections are based on local, regional, and national data, as well as likely changes to 

economic and demographic conditions. Therefore, the projections include employment associated 

with the continuation of current patterns in OCS leasing activity, as well as the continuation of trends 

in other industries important to the region.

Woods & Poole Economics, Inc. (2015) provides county-level economic and demographic 

data for prior years, as well as forecasts of these data through 2050. Table 4-31 aggregates Woods 

& Poole data by EIA and presents each EIA’s population, employment, gross regional product, labor 

income, median age, male percentage, and race composition. The largest EIAs (presented in 

descending order of gross regional product) are TX-3 (which includes Houston and Galveston), FL-5 

(which includes Tampa), LA-6 (which includes New Orleans), LA-5 (which includes Baton Rouge), 
4-406 Gulf of Mexico Multisale EIS

FL-6, and TX-1. The smallest EIAs (presented in ascending order of gross regional product) are 

MS-2, TX-6, AL-2, LA-2, and TX-4. Table 4-31 presents Woods & Poole’s forecasted levels of 

economic and demographic variables in 2050. From 2015 through 2050, the fastest population and 

employment growth is forecast in TX-1, TX-3, FL-6, and FL-4; the slowest growth is forecast in LA-6, 

TX-5, AL-2, and MS-1.

Table 4-31. Economic and Demographic Information for BOEM's Economic Impact Areas in 2050.

Economic Variables Demographic Variables

EIA Population Employment

Gross 

Regional 

Product1

Labor 

Income

Median 

Age

Male 

% White Black Hispanic Native American Asian

Texas

TX-1 3,211,678 1,510,514 122,978,193 70,686,006 37.1 49.6% 3.9% 0.5% 94.8% 0.0% 0.8%

TX-2 901,108 594,209 74,012,799 37,740,590 39.3 50.9% 26.1% 6.4% 64.8% 0.3% 2.5%

TX-3 11,318,207 7,262,133 1,095,629,086 667,969,020 37.7 50.1% 18.8% 14.1% 53.8% 0.2% 13.0%

TX-4 244,211 93,227 7,722,339 4,108,509 41.2 49.8% 61.6% 10.3% 26.3% 0.5% 1.4%

TX-5 407,234 257,973 29,621,937 17,100,218 40.4 53.4% 32.9% 23.2% 40.0% 0.3% 3.5%

TX-6 63,947 34,006 2,596,031 1,311,359 40.6 49.9% 52.4% 30.0% 15.5% 0.6% 1.4%

Louisiana

LA-1 248,184 158,977 18,087,099 9,507,742 40.5 48.8% 65.3% 26.8% 4.9% 0.7% 2.3%

LA-2 108,507 56,413 7,166,445 3,673,737 35.8 51.3% 68.3% 15.5% 12.1% 1.5% 2.6%

LA-3 776,541 522,500 71,038,683 33,614,841 40.2 49.5% 62.4% 30.6% 4.9% 0.5% 1.6%

LA-4 428,273 322,607 46,645,705 22,575,517 41.5 49.6% 56.0% 26.2% 11.3% 3.6% 3.0%

LA-5 1,253,207 823,740 94,931,543 50,201,612 42.7 49.2% 49.4% 41.3% 6.1% 0.3% 3.0%

LA-6 924,191 755,835 94,351,565 50,648,128 39.5 49.3% 32.7% 42.0% 19.6% 0.4% 5.3%

LA-7 647,551 335,006 34,109,728 18,482,013 41.5 48.5% 64.4% 23.5% 9.6% 0.4% 2.0%

Mississippi

MS-1 527,738 298,996 21,694,991 16,628,795 41.0 49.2% 63.0% 24.4% 9.3% 0.4% 2.8%

MS-2 87,917 28,786 1,880,313 1,129,831 41.1 53.1% 72.0% 24.9% 2.4% 0.3% 0.4%

Alabama

AL-1 840,489 525,223 43,583,841 25,996,755 41.9 47.9% 61.7% 28.6% 6.2% 0.8% 2.7%

AL-2 116,672 66,584 5,802,458 3,319,000 46.3 50.7% 45.4% 46.6% 2.9% 4.2% 0.9%

Florida

FL-1 1,271,987 756,445 67,816,779 40,841,162 42.5 51.9% 69.3% 16.9% 9.3% 0.6% 3.9%

FL-2 721,561 396,668 33,967,696 20,313,641 45.2 52.1% 53.3% 37.6% 5.9% 0.4% 2.8%

FL-3 335,944 132,391 10,488,863 6,078,422 44.1 56.4% 64.1% 26.4% 7.9% 0.4% 1.2%

FL-4 2,445,932 1,050,736 78,635,995 48,938,904 52.0 50.3% 69.2% 12.7% 14.7% 0.3% 3.1%

FL-5 6,237,613 3,589,267 365,775,112 220,553,234 45.0 49.5% 45.3% 14.1% 34.0% 0.2% 6.4%

FL-6 2,465,544 1,320,017 117,042,429 70,468,182 47.0 51.0% 50.9% 7.4% 40.0% 0.2% 1.5%

1 Gross Regional Product is presented in thousands of dollars.

Source: Woods & Poole Economics, Inc., 2015.
Description of the Affected Environment and Impact Analysis 4-407

Overall Energy Market

The oil and gas industry would be impacted by the various forces affecting supply and 

demand for energy products. For example, the rapid expansion of U.S. onshore energy production 

in recent years contributed to a noticeable decline in oil prices beginning in late 2014. Energy supply 

and demand has also been affected by international developments, including policy towards Iran and 

decisions made by the Organization for Petroleum Exporting Countries. Demand for energy 

products would also be affected by various factors, including economic activity, technological 

developments, and government policies. The Energy Information Administration provides forecasts 

of energy markets that incorporate these various factors. In particular, the Energy Information 

Administration publishes monthly short-term (2-year) forecasts (USDOE, Energy Information 

Administration, 2015h) and annual long-term (25-year) forecasts (USDOE, Energy Information 

Administration, 2015i). The incremental contribution of a proposed action relative to the outlooks 

described in these reports is expected to be minimal.

Incomplete or Unavailable Information

Even after evaluating the information above, there is still incomplete or unavailable 

information. This information primarily relates to the onshore geographic distributions of economic 

impacts arising from the OCS Program, which would allow BOEM to better estimate the impacts 

from routine activities and cumulative impacts. This information is difficult to obtain since most data 

sources do not adequately differentiate between onshore and offshore oil and gas activities. In 

addition, standard data sources do not trace revenue and corporate profit streams to ultimate 

expenditures. BOEM used reasonably accepted scientific methodologies to extrapolate from 

existing information in completing the relevant analysis and formulating the conclusions presented 

here. For example, BOEM used the model MAG-PLAN to estimate the impacts of the alternatives 

and 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.

4.14.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

Alternative A entails holding a regionwide lease sale. The impacts of Alternative A would 

correspond to the impacts discussed above. This chapter will clarify the numerical impact estimates 

for Alternative A. The MAG-PLAN’s estimates of the total employment, labor income, and valueadded expenditure impacts for the low and high scenarios are presented in Tables 4-32 and 4-33. 

These tables present the average values (over 50 years), peak values, and percent of peak values 

relative to total employment, labor income, and value-added in each EIA. The average values are 

calculated over 50 years for consistency and because that is the time horizon over which activities 

arising from the alternatives are expected to occur. In the low scenario, a proposed action would 

support a peak of 9,500 jobs, $600 million in labor income, and $970 million in value-added benefits 

throughout the United States. Most of these impacts would occur in the Gulf of Mexico region, 

particularly in coastal Texas and Louisiana. The EIAs that would experience the highest economic 

impacts are TX-3, TX-2, LA-3, LA-4, LA-6, MS-1, and AL-1. However, these impacts would 
4-408 Gulf of Mexico Multisale EIS

represent a small fraction of each EIA’s economy. In the high scenario, a proposed action would 

support a peak of 27,000 jobs, $1,7 billion in labor income, and $2.6 billion in value-added. The 

geographic distributions of impacts would be similar to those of the low scenario. However, these 

expenditure impacts would represent less than 1 percent of the economies of all EIAs. The impacts 

of the very high scenario would be double the impacts of the high scenario. However, as discussed 

previously, the very high scenario is unlikely to occur.

Table 4-32. Gulf of Mexico Single Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Texas

TX-1 20 220 0.0% 1,000 9,000 0.0% 1,000 13,000 0.0%

TX-2 60 610 0.1% 3,000 30,000 0.1% 4,000 44,000 0.0%

TX-3 250 1,900 0.1% 20,000 150,000 0.1% 31,000 241,000 0.0%

TX-4 0 20 0.0% 0 1,000 0.0% 0 2,000 0.0%

TX-5 10 50 0.0% 0 3,000 0.0% 1,000 5,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 340 2,660 – 25,000 185,000 – 38,000 294,000 –

Rest of Texas 70 460 – 4,000 29,000 – 7,000 51,000 –

Texas Total 410 3,120 – 28,000 213,000 – 45,000 345,000 – 

Louisiana

LA-1 20 170 0.2% 2,000 12,000 0.2% 2,000 17,000 0.2%

LA-2 0 10 0.0% 0 0 0.0% 0 0 0.0%

LA-3 50 340 0.2% 3,000 16,000 0.1% 4,000 26,000 0.1%

LA-4 70 600 0.3% 5,000 40,000 0.3% 7,000 57,000 0.2%

LA-5 20 200 0.1% 1,000 10,000 0.0% 2,000 16,000 0.0%

LA-6 60 500 0.1% 4,000 30,000 0.1% 5,000 42,000 0.1%

LA-7 10 80 0.1% 1,000 4,000 0.0% 1,000 6,000 0.0%

All Louisiana EIAs 250 1,870 – 14,000 113,000 – 21,000 163,000 –

Rest of Louisiana 40 300 – 2,000 14,000 – 4,000 28,000 –

Louisiana Total 290 2,150 – 16,000 126,000 – 25,000 190,000 –

Mississippi

MS-1 50 470 0.3% 3,000 24,000 0.3% 4,000 35,000 0.3%

MS-2 0 20 0.2% 0 1,000 0.1% 0 1,000 0.1%

All Mississippi EIAs 60 490 – 3,000 25,000 – 4,000 36,000 –

Rest of Mississippi 50 350 – 2,000 16,000 – 4,000 29,000 –

Mississippi Total 100 830 – 5,000 41,000 – 8,000 64,000 –

Alabama

AL-1 60 600 0.2% 3,000 28,000 0.2% 5,000 47,000 0.2%

AL-2 10 40 0.1% 0 2,000 0.1% 0 3,000 0.1%

All Alabama EIAs 70 640 – 3,000 30,000 – 5,000 51,000 –

Rest of Alabama 40 310 – 2,000 16,000 – 4,000 30,000 –

Alabama Total 110 940 – 5,000 45,000 – 9,000 80,000 –

Florida

FL-1 10 90 0.0% 0 6,000 0.0% 1,000 11,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 1,000 0.0% 0 1,000 0.0%
Description of the Affected Environment and Impact Analysis 4-409

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 10 100 – 1,000 7,000 – 1,000 12,000 –

Rest of Florida 40 290 – 2,000 14,000 – 4,000 27,000 –

Florida Total 50 380 – 3,000 20,000 – 5,000 37,000 –

All States

All EIAs in All States 720 5,730 – 45,000 358,000 – 69,000 550,000 –

All Gulf States 960 7,420 – 58,000 445,000 – 91,000 713,000 –

USA

Rest of the United 

States 220 2,150 – 14,000 136,000 – 27,000 262,000 – 

Totals

Total Expenditure 

Impacts 1,180 9,540 – 72,000 579,000 – 118,000 970,000 – 

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Table 4-33. Gulf of Mexico Single High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Texas

TX-1 90 480 0.0% 4,000 20,000 0.0% 6,000 29,000 0.0%

TX-2 320 1,310 0.1% 17,000 66,000 0.1% 24,000 95,000 0.0%

TX-3 2,170 7,640 0.1% 178,000 617,000 0.1% 246,000 865,000 0.0%

TX-4 10 40 0.0% 1,000 2,000 0.0% 1,000 3,000 0.0%

TX-5 40 140 0.0% 2,000 8,000 0.0% 3,000 12,000 0.0%

TX-6 0 10 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 2,630 9,490 – 201,000 705,000 – 281,000 997,000 –

Rest of Texas 360 1,200 – 22,000 73,000 – 37,000 126,000 –

Texas Total 2,990 10,650 – 223,000 778,000 – 318,000 1,122,000 –

Louisiana

LA-1 160 430 0.2% 11,000 30,000 0.2% 16,000 43,000 0.2%

LA-2 10 20 0.0% 0 1,000 0.0% 0 1,000 0.0%

LA-3 460 1,240 0.2% 23,000 61,000 0.1% 34,000 92,000 0.1%

LA-4 480 1,460 0.3% 31,000 95,000 0.3% 45,000 137,000 0.2%

LA-5 200 590 0.1% 10,000 28,000 0.0% 15,000 43,000 0.0%

LA-6 530 1,540 0.1% 31,000 90,000 0.1% 44,000 125,000 0.1%

LA-7 100 260 0.1% 4,000 12,000 0.0% 6,000 17,000 0.0%

All Louisiana EIAs 1,930 5,470 – 110,000 313,000 – 161,000 454,000 –

Rest of Louisiana 230 730 – 11,000 34,000 – 20,000 65,000 –

Louisiana Total 2,160 6,180 – 121,000 347,000 – 181,000 517,000 –

Mississippi

MS-1 450 1,400 0.3% 20,000 64,000 0.3% 30,000 94,000 0.3%

MS-2 30 70 0.2% 1,000 2,000 0.1% 1,000 3,000 0.1%

All Mississippi EIAs 480 1,460 – 21,000 65,000 – 31,000 97,000 –
4-410 Gulf of Mexico Multisale EIS

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Rest of Mississippi 250 840 – 11,000 39,000 – 19,000 67,000 –

Mississippi Total 730 2,280 – 32,000 103,000 – 50,000 163,000 –

Alabama

AL-1 510 1,650 0.2% 21,000 70,000 0.2% 34,000 115,000 0.2%

AL-2 40 130 0.1% 1,000 5,000 0.1% 3,000 9,000 0.1%

All Alabama EIAs 550 1,780 – 23,000 75,000 – 36,000 124,000 –

Rest of Alabama 200 710 – 10,000 35,000 – 18,000 65,000 –

Alabama Total 760 2,470 – 33,000 110,000 – 54,000 189,000 –

Florida

FL-1 20 150 0.0% 1,000 11,000 0.0% 2,000 18,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 10 20 0.0% 0 1,000 0.0% 1,000 2,000 0.0%

FL-5 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 30 180 – 2,000 12,000 – 3,000 21,000 –

Rest of Florida 220 720 – 12,000 38,000 – 20,000 66,000 –

Florida Total 260 870 – 14,000 48,000 – 24,000 83,000 –

All States

All EIAs in All States 5,630 18,360 – 356,000 1,165,000 – 512,000 1,682,000 –

All Gulf States 6,900 22,420 – 422,000 1,383,000 – 627,000 2,069,000 –

USA

Rest of the United 

States 1,080 4,680 – 69,000 299,000 – 128,000 564,000 – 

Totals

Total Expenditure 

Impacts 7,980 27,030 – 491,000 1,669,000 – 755,000 2,605,000 – 

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Alternative A would generate government revenues through bonus bids, rental payments, 

and royalty payments. In the low scenario, a regionwide lease sale would generate approximately 

$260 million in bonus bids, $46 million in total rental payments (with an annual peak of $6.7 million), 

and $1.7 billion in royalty payments (with an annual peak of $119 million). In the high scenario, a 

regionwide lease sale would generate approximately $520 million in bonus bids, $98 million in total 

rental payments (with an annual peak of $14 million), and $19.8 billion in total royalty payments (with 

an annual peak of $1.2 billion). The revenue impacts of the very high scenario would be double the 

impacts of the high scenario. The corporate profit and market impacts, the adverse impacts arising 

from routine activities and accidental events, and the cumulative impacts would be proportional to 

the amount of activities as described above.

Overall, Alternative A would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Some of these impacts would 

be concentrated along the Gulf Coast, while others would be widely distributed. Alternative A would 

also lead to negative economic impacts arising from accidental events and other sources. A 
Description of the Affected Environment and Impact Analysis 4-411

proposed action should be viewed in light of the OCS Program, as well the numerous forces that can 

affect energy markets and the overall economy. Most of the incremental economic impacts of a 

proposed action are forecast to be beneficial, although there would be some negligible to minor

adverse impacts due to oil spills and to effects on industries that compete with the offshore oil and 

gas industry for resources. Therefore, the impacts of Alternative A would lead to beneficial impacts, 

as well as some offsetting negligible to minor adverse impacts.

4.14.2.2.2 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B would entail leasing only in the CPA and EPA. As discussed above, the low 

and high scenarios assume that Alternative B is chosen in the context of typically holding two lease 

sales per year. If Alternative B were chosen in the context of the CPA/EPA area only being offered 

once in a year, the economic impacts would be approximately double those presented here because 

leasing activities would not be spread over the two lease sales; the maximum impacts would 

correspond to the very high scenario discussed above.

The positive economic impacts of Alternative B would be slightly less than for Alternative A. 

The MAG-PLAN’s estimates of the total employment, labor income, and value-added impacts for the 

low and high scenarios are presented in Tables 4-34 and 4-35. These tables present the average 

values (over 50 years), peak values, and percent of peak values relative to total employment, labor 

income, and value-added in each EIA. In the low scenario, Alternative B would support a peak of 

7,300 jobs, $440 million in labor income, and $740 million in value-added benefits throughout the 

United States. Most of these impacts would occur in the Gulf of Mexico region, particularly in coastal 

Texas and Louisiana. The EIAs that would experience the highest economic impacts are TX-3, 

TX-2, LA-3, LA-4, LA-6, MS-1, and AL-1. The proportion of total economic impacts would be slightly 

higher in Louisiana, Mississippi, and Alabama and lower in Texas compared with Alternative A. 

However, these impacts would represent small fractions of each EIA’s economy. In the high 

scenario, Alternative B would support a peak of 20,000 jobs, $1.2 billion in labor income, and 

$1.9 billion in value-added. The geographic distributions of impacts would be similar to those of the 

low scenario. However, the expenditure impacts would represent <1 percent of the economies of all 

EIAs. The impacts of the very high scenario would be double the impacts of the high scenario. 

However, as discussed previously, the very high scenario is unlikely to occur. The revenue, 

corporate profit, market, and adverse impacts would also be proportionately lower. The nature of 

potential accidental events would be the same, although slightly fewer activities would likely lead to 

slightly fewer accidental events.

Overall, Alternative B would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Some of these impacts would 

be concentrated along the Gulf Coast, while others would be widely distributed. Alternative B would 

also lead to negative economic impacts arising from accidental events and other sources. The 

proposed action should be viewed in light of the OCS Program, as well the numerous forces that can 

affect energy markets and the overall economy. Most of the incremental economic impacts of the 
4-412 Gulf of Mexico Multisale EIS

proposed action are forecast to be positive, although there would be some negligible to minor 

adverse impacts due to oil spills and to effects on industries that compete with the offshore oil and 

gas industry for resources. The differences in the adverse impacts among the alternatives would be 

roughly proportional to the level of OCS oil- and gas-related activities, but the precise impacts would 

depend on the types and locations of activities.

Table 4-34. CPA Single Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak %

Texas

TX-1 10 90 0.0% 0 4,000 0.0% 1,000 7,000 0.0%

TX-2 40 390 0.1% 2,000 19,000 0.1% 3,000 29,000 0.0%

TX-3 160 1,040 0.1% 13,000 85,000 0.1% 20,000 139,000 0.0%

TX-4 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

TX-5 0 20 0.0% 0 1,000 0.0% 0 2,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 210 1,480 – 16,000 107,000 – 24,000 173,000 –

Rest of Texas 50 350 – 3,000 22,000 – 5,000 39,000 –

Texas Total 260 1,830 – 19,000 129,000 – 30,000 212,000 –

Louisiana

LA-1 20 160 0.2% 2,000 12,000 0.2% 2,000 17,000 0.2%

LA-2 0 10 0.0% 0 0 0.0% 0 0 0.0%

LA-3 50 310 0.2% 2,000 14,000 0.1% 4,000 23,000 0.1%

LA-4 60 530 0.3% 4,000 36,000 0.3% 6,000 51,000 0.2%

LA-5 20 190 0.1% 1,000 10,000 0.0% 2,000 15,000 0.0%

LA-6 60 490 0.1% 4,000 29,000 0.1% 5,000 40,000 0.1%

LA-7 10 80 0.1% 0 4,000 0.0% 1,000 6,000 0.0%

All Louisiana EIAs 230 1,760 – 14,000 106,000 – 20,000 152,000 –

Rest of Louisiana 30 220 – 2,000 10,000 – 3,000 21,000 –

Louisiana Total 260 1,970 – 15,000 117,000 – 23,000 173,000 –

Mississippi

MS-1 50 440 0.3% 3,000 23,000 0.3% 4,000 32,000 0.3%

MS-2 0 20 0.2% 0 1,000 0.1% 0 1,000 0.1%

All Mississippi EIAs 50 460 – 3,000 23,000 – 4,000 33,000 –

Rest of Mississippi 40 270 – 2,000 13,000 – 3,000 22,000 –

Mississippi Total 90 720 -- 4,000 36,000 -- 7,000 55,000 --

Alabama

AL-1 60 530 0.2% 3,000 25,000 0.2% 4,000 41,000 0.2%

AL-2 0 40 0.1% 0 2,000 0.1% 0 3,000 0.1%

All Alabama EIAs 60 570 – 3,000 27,000 – 5,000 44,000 –

Rest of Alabama 30 240 – 2,000 12,000 – 3,000 24,000 –

Alabama Total 100 810 – 5,000 39,000 – 8,000 67,000 –
Description of the Affected Environment and Impact Analysis 4-413

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak %

Florida

FL-1 0 60 0.0% 0 4,000 0.0% 1,000 7,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 10 70 – 0 5,000 – 1,000 8,000 –

Rest of Florida 30 220 – 2,000 11,000 – 3,000 21,000 –

Florida Total 40 290 – 2,000 15,000 – 4,000 29,000 –

All States

All EIAs in All States 560 4,340 – 35,000 269,000 – 53,000 411,000 – 

All Gulf States 750 5,640 – 45,000 336,000 – 71,000 536,000 –

USA

Rest of the United 

States 180 1,640 – 11,000 104,000 – 21,000 200,000 – 

Totals

Total Expenditure 

Impacts 930 7,280 – 56,000 440,000 – 92,000 736,000 – 

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Table 4-35. CPA Single High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Texas

TX-1 50 140 0.0% 3,000 7,000 0.0% 4,000 11,000 0.0%

TX-2 220 630 0.1% 11,000 33,000 0.1% 16,000 47,000 0.0%

TX-3 1,740 5,220 0.1% 145,000 435,000 0.1% 199,000 591,000 0.0%

TX-4 10 20 0.0% 0 1,000 0.0% 1,000 2,000 0.0%

TX-5 10 40 0.0% 1,000 2,000 0.0% 1,000 3,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 2,030 6,060 – 160,000 478,000 – 221,000 654,000 –

Rest of Texas 310 860 – 19,000 53,000 – 31,000 90,000 –

Texas Total 2,340 6,930 – 179,000 531,000 – 252,000 744,000 –

Louisiana

LA-1 160 420 0.2% 11,000 29,000 0.2% 16,000 43,000 0.2%

LA-2 10 20 0.0% 0 1,000 0.0% 0 1,000 0.0%

LA-3 420 1,110 0.2% 21,000 55,000 0.1% 31,000 81,000 0.1%

LA-4 430 1,200 0.3% 29,000 80,000 0.3% 42,000 115,000 0.2%

LA-5 200 570 0.1% 9,000 27,000 0.0% 14,000 41,000 0.0%

LA-6 510 1,470 0.1% 30,000 86,000 0.1% 42,000 119,000 0.1%

LA-7 90 250 0.1% 4,000 11,000 0.0% 6,000 16,000 0.0%

All Louisiana EIAs 1,820 5,040 – 104,000 288,000 – 152,000 417,000 –

Rest of Louisiana 190 520 – 9,000 24,000 – 17,000 46,000 –
4-414 Gulf of Mexico Multisale EIS

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Louisiana Total 2,010 5,540 – 113,000 312,000 – 168,000 461,000 –

Mississippi

MS-1 440 1,290 0.3% 19,000 57,000 0.3% 29,000 85,000 0.3%

MS-2 30 70 0.2% 1,000 2,000 0.1% 1,000 3,000 0.1%

All Mississippi EIAs 470 1,360 – 20,000 59,000 – 30,000 88,000 –

Rest of Mississippi 210 590 – 9,000 27,000 – 16,000 47,000 –

Mississippi Total 680 1,950 – 29,000 86,000 – 46,000 134,000 –

Alabama

AL-1 500 1,510 0.2% 21,000 63,000 0.2% 33,000 101,000 0.2%

AL-2 40 120 0.1% 1,000 4,000 0.1% 3,000 7,000 0.1%

All Alabama EIAs 540 1,630 – 22,000 67,000 – 35,000 108,000 –

Rest of Alabama 170 490 – 8,000 24,000 – 15,000 44,000 – 

Alabama Total 710 2,120 – 30,000 92,000 – 50,000 152,000 –

Florida

FL-1 20 90 0.0% 1,000 6,000 0.0% 2,000 11,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 1,000 0.0% 0 1,000 0.0%

FL-5 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 30 110 – 1,000 7,000 – 3,000 13,000 –

Rest of Florida 190 510 – 10,000 27,000 – 17,000 46,000 –

Florida Total 220 610 – 12,000 33,000 – 20,000 57,000 –

All States

All EIAs in All States 4,890 14,190 – 307,000 899,000 – 440,000 1,278,000 –

All Gulf States 5,950 17,140 – 363,000 1,054,000 – 536,000 1,549,000 –

USA

Rest of the United 

States 890 2,990 – 57,000 192,000 – 106,000 358,000 – 

Totals

Total Expenditure 

Impacts 6,840 20,140 – 420,000 1,246,000 – 642,000 1,907,000 – 

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

4.14.2.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Alternative C would entail leasing only in the WPA. As discussed above, the low and high 

scenarios assume that Alternative C is chosen in the context of typically holding two lease sales per 

year. If Alternative C were chosen in the context of the WPA area only being offered once in a year, 

the economic impacts would be approximately double those presented here because leasing 

activities would not be spread over the two lease sales; the maximum impacts would correspond to 

the very high scenario discussed above.
Description of the Affected Environment and Impact Analysis 4-415

The positive economic impacts of Alternative C would be less than for Alternative A, 

particularly since less activity generally occurs in the WPA relative to the CPA. MAG-PLAN’s 

estimates of the total employment, labor income, and value-added impacts for the low and high 

scenarios are presented in Tables 4-36 and 4-37. These tables present the average values (over 

50 years), peak values, and the percent of peak values relative to total employment, labor income, 

and value-added in each EIA. In the low scenario, Alternative C would support a peak of 2,300 jobs, 

$140 million in labor income, and $230 million in value-added benefits throughout the United States. 

Most of these impacts would occur in the Gulf Region. The EIAs that would experience the highest 

economic impacts are TX-3, TX-2, TX-1, LA-4, and AL-1. The proportion of total economic impacts 

would be higher in Texas (and lower in the other Gulf States) compared to Alternative A. However, 

these impacts would represent small fractions of each EIAs economy. In the high scenario, 

Alternative C would support a peak of 6,900 jobs, $420 million in labor income, and $700 million in 

value-added. The geographic distributions of impacts would be similar to those of the low scenario. 

The impacts of the very high scenario would be double the impacts of the high scenario. However, 

as discussed previously, the very high scenario is unlikely to occur. The revenue, corporate profit, 

market, and adverse impacts would also be proportionately lower. The nature of potential accidental 

events would be the same, although slightly fewer activities would likely lead to slightly fewer 

accidental events.

Overall, Alternative C would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Some of these impacts would 

be concentrated along the Gulf Coast, while others would be widely distributed. Alternative C would 

also lead to negative economic impacts arising from accidental events and other sources. A 

proposed action should be viewed in light of the OCS Program, as well the numerous forces that can 

affect energy markets and the overall economy. Most of the incremental economic impacts of a 

proposed action are forecast to be positive, although there would be some negligible to minor

adverse impacts due to oil spills and to effects on industries that compete with the offshore oil and 

gas industry for resources.

Table 4-36. WPA Single Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts (number of 

jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak %

Texas

TX-1 10 130 0.0% 0 4,000 0.0% 1,000 6,000 0.0%

TX-2 20 220 0.1% 1,000 10,000 0.1% 2,000 15,000 0.0%

TX-3 100 860 0.1% 7,000 65,000 0.1% 11,000 102,000 0.0%

TX-4 0 10 0.0% 0 0 0.0% 0 0 0.0%

TX-5 0 30 0.0% 0 2,000 0.0% 0 3,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 130 1,180 – 9,000 77,000 – 13,000 121,000 –

Rest of Texas 10 110 – 1,000 7,000 – 1,000 12,000 –

Texas Total 150 1,290 – 10,000 84,000 – 15,000 133,000 –
4-416 Gulf of Mexico Multisale EIS

Economic 

Impact Area

Employment Impacts (number of 

jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak %

Louisiana

LA-1 0 0 0.2% 0 0 0.2% 0 0 0.2%

LA-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

LA-3 0 30 0.2% 0 2,000 0.1% 0 3,000 0.1%

LA-4 10 70 0.3% 0 4,000 0.3% 1,000 6,000 0.2%

LA-5 0 10 0.1% 0 0 0.0% 0 1,000 0.0%

LA-6 0 20 0.1% 0 1,000 0.1% 0 2,000 0.1%

LA-7 0 0 0.1% 0 0 0.0% 0 0 0.0%

All Louisiana EIAs 20 110 – 1,000 7,000 – 1,000 10,000 –

Rest of Louisiana 10 80 – 0 4,000 – 1,000 7,000 –

Louisiana Total 20 180 – 1,000 9,000 – 2,000 16,000 –

Mississippi

MS-1 0 30 0.3% 0 2,000 0.3% 0 3,000 0.3%

MS-2 0 0 0.2% 0 0 0.1% 0 0 0.1%

All Mississippi EIAs 0 30 – 0 2,000 – 0 3,000 –

Rest of Mississippi 10 90 – 0 4,000 – 1,000 7,000 –

Mississippi Total 10 110 – 1,000 5,000 – 1,000 9,000 –

Alabama

AL-1 0 70 0.2% 0 3,000 0.2% 0 7,000 0.2%

AL-2 0 0 0.1% 0 0 0.1% 0 0 0.1%

All Alabama EIAs 0 70 – 0 3,000 – 0 7,000 –

Rest of Alabama 10 70 – 0 3,000 – 1,000 7,000 –

Alabama Total 10 120 – 1,000 6,000 – 1,000 13,000 –

Florida

FL-1 0 30 0.0% 0 2,000 0.0% 0 4,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 0 30 – 0 2,000 – 0 4,000 –

Rest of Florida 10 70 – 0 3,000 – 1,000 6,000 –

Florida Total 10 90 – 1,000 5,000 – 1,000 9,000 –

All States

All EIAs in All States 160 1,400 – 10,000 89,000 – 16,000 139,000 –

All Gulf States 210 1,790 – 13,000 109,000 – 20,000 177,000 –

USA

Rest of the United 

States 50 500 – 3,000 32,000 – 6,000 62,000 – 

Totals

Total Expenditure 

Impacts 250 2,260 – 16,000 139,000 – 26,000 234,000 – 

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.
Description of the Affected Environment and Impact Analysis 4-417

Table 4-37. WPA Single High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Texas

TX-1 40 340 0.0% 2,000 12,000 0.0% 2,000 18,000 0.0%

TX-2 110 680 0.1% 5,000 33,000 0.1% 8,000 48,000 0.0%

TX-3 430 2,420 0.1% 32,000 182,000 0.1% 47,000 274,000 0.0%

TX-4 0 20 0.0% 0 1,000 0.0% 0 2,000 0.0%

TX-5 20 110 0.0% 1,000 5,000 0.0% 2,000 9,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 600 3,430 – 41,000 227,000 – 60,000 342,000 –

Rest of Texas 60 330 – 3,000 20,000 – 6,000 36,000 –

Texas Total 660 3,720 – 44,000 247,000 – 66,000 378,000 –

Louisiana

LA-1 0 10 0.2% 0 0 0.2% 0 1,000 0.2%

LA-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

LA-3 40 120 0.2% 2,000 7,000 0.1% 3,000 10,000 0.1%

LA-4 40 260 0.3% 3,000 15,000 0.3% 4,000 22,000 0.2%

LA-5 10 20 0.1% 0 1,000 0.0% 0 2,000 0.0%

LA-6 20 70 0.1% 1,000 5,000 0.1% 2,000 6,000 0.1%

LA-7 0 10 0.1% 0 1,000 0.0% 0 1,000 0.0%

All Louisiana EIAs 110 430 – 6,000 25,000 – 9,000 37,000 –

Rest of Louisiana 40 200 – 2,000 10,000 – 3,000 19,000 –

Louisiana Total 150 640 – 8,000 35,000 – 12,000 56,000 –

Mississippi

MS-1 10 110 0.3% 1,000 7,000 0.3% 1,000 9,000 0.3%

MS-2 0 0 0.2% 0 0 0.1% 0 0 0.1%

All Mississippi EIAs 10 110 – 1,000 7,000 – 1,000 10,000 –

Rest of Mississippi 40 240 – 2,000 11,000 – 3,000 20,000 –

Mississippi Total 50 330 – 3,000 17,000 – 4,000 28,000 –

Alabama

AL-1 10 140 0.2% 1,000 7,000 0.2% 1,000 14,000 0.2%

AL-2 0 10 0.1% 0 0 0.1% 0 1,000 0.1%

All Alabama EIAs 10 150 – 1,000 7,000 – 1,000 15,000 –

Rest of Alabama 30 220 – 2,000 11,000 – 3,000 21,000 –

Alabama Total 50 350 – 2,000 18,000 – 4,000 37,000 –

Florida

FL-1 10 60 0.0% 0 4,000 0.0% 1,000 7,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 10 70 – 0 5,000 – 1,000 9,000 –

Rest of Florida 30 210 – 2,000 11,000 – 3,000 20,000 –

Florida Total 40 270 – 2,000 14,000 – 4,000 26,000 –

All States

All EIAs in All States 750 4,170 – 49,000 266,000 – 72,000 404,000 –

All Gulf States 950 5,280 – 59,000 329,000 – 91,000 520,000 –
4-418 Gulf of Mexico Multisale EIS

While the entire petroleum 

industry (onshore, State 

waters, and OCS) has 

developed over decades and 

is deeply intertwined in the 

Gulf of Mexico region’s 

communities and economies, 

a single lease sale is like a 

blip on a radar screen, i.e., 

one tiny piece of a vastly 

complex social and economic 

structure.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

USA

Rest of the United States 190 1,680 – 12,000 106,000 – 23,000 206,000 –

Totals

Total Expenditure Impacts 1,130 6,890 – 71,000 423,000 – 113,000 698,000 –

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

4.14.2.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D only slightly reduces the available areas for leasing. Therefore, the economic 

impacts of Alternative D would the same or only slightly less than the impacts of Alternative A, B, 

or C.

4.14.2.2.5 Alternative E—No Action

The selection of Alternative E would prevent the positive economic impacts described above 

from occurring; it would also prevent the associated negative impacts from occurring. The impacts 

of selecting Alternative E would depend on the extent to which the public were to interpret it as a 

signal of a policy change that would continue into future lease sales. For example, if the public were 

to interpret the selection of Alternative E as a one-time event, the economic impacts would be 

limited. However, the selection of Alternative E could impact longer-term oil and gas industry 

investment decisions if it introduced uncertainty regarding the OCS Program. This is particularly true 

given the long life cycles of oil and gas investment projects.

4.14.3 Social Factors (Including Environmental Justice)

The petroleum industry as a whole in the Gulf of Mexico 

region has matured over several decades and is well-developed, 

expansive, extensive, and deeply intertwined in the regional 

communities and economies of the five coastal states, i.e.,

Texas, Louisiana, Mississippi, Alabama, and Florida. An 

inherent complication in conducting an impact analysis of OCS 

oil- and gas-related activities lies in the fact that the industry 

involves onshore, State offshore, and Federal OCS exploration, 

development, and production. Teasing out the OCS oil- and 

gas-related impacts from the impacts of activities onshore and in 

State waters is difficult, if not impossible. Moreover, this longlived, well-developed, and extensive industry functions within a 

much larger context, a socioeconomic framework that weaves 
Description of the Affected Environment and Impact Analysis 4-419

through the region in a complex, inter-connected grid-like manner. Nothing occurs as an isolated 

event, but rather results from and simultaneously triggers other events, all of which are experienced 

at varying degrees of a negative or positive impact. For example, when oil prices drop and then 

gasoline prices drop, this positively impacts individuals and businesses who buy fuel. When oil 

prices remain low for many months, negative impacts begin to appear. Companies start trimming 

costs by reducing the number of employees to cut operational costs. Laid-off employees no longer 

have income to make purchases and the businesses where workers would normally spend their 

money began to suffer and, when necessary, people began moving out of the area to find other 

work, leading to a negative impact on the housing market, depressing real estate prices as the 

number of units available for rent or sale outgrows the demand. A negative impact for some (i.e., 

sellers and landlords) becomes a positive impact for others (i.e., buyers and renters). This is just 

one example of an event unrelated to OCS oil- and gas-related activities leading to dual ripple 

impacts (negative and positive) through communities and illustrates the complexity of the 

socioeconomic framework. Within this context, a single lease sale is like a blip on a radar screen, 

i.e., one tiny piece of a vastly complex social and economic structure. A single lease sale’s main 

impact on communities would be to contribute to the maintenance of current employment levels and 

not to create new jobs; not to cause people to move into the region; not to cause new roads, 

schools, or hospitals to be built; and not to cause large public works improvements. A single lease 

sale would solely help to maintain what decades of economic development have built, the complex 

Gulf of Mexico region that exists today.

While this chapter is titled “social factors,” the resource discussed here is essentially human 

beings. The list of potential impact-producing factors is, in a sense, nearly limitless because the 

industry involves people at all levels; it simultaneously affects and is affected by people, their 

communities, and their daily lives. Most of the impacts to people are positive, e.g., in the form of 

direct employment in the industry, indirect employment in the extensive support sectors, and 

employees’ spent wages and tax revenues that support the community businesses and services. 

After describing the affected environment, this impact analysis addresses routine activities related to 

the oil and gas industry and accidental events that may occur from OCS oil- and gas-related 

activities as a result of a single lease sale, as well as the cumulative impacts of OCS oil- and gasrelated and non-OCS oil- and gas-related impact-producing factors. An environmental justice 

determination follows in Chapter 4.14.3.3. 

Impact-Level Definitions

Impacts to people and communities may be positive as well as negative. For example, 

increased economic demand would lead to more hiring, and this additional employment would 

further the positive economic trend as new workers spend their wages in the community. Negative 

and positive impacts are measured on the following scale:

• Negligible – Little or no measureable impact.

• Minor – Small-scale measurable impact, temporary in duration, and 

geographically small area (less than county/parish level).
4-420 Gulf of Mexico Multisale EIS

• Moderate – Medium-scale measurable impact, may last from a few weeks to 1 

year, and geographically may affect multiple counties/parishes.

• Major – Large-scale measurable or potentially unmeasurable impact, long lasting 

(1 year to many years), and may occur over a geographically large regional area.

4.14.3.1 Description of the Affected Environment

The affected environment that comprises the baseline for the social factors’ environmental 

impact analysis is geographically distributed across 23 BOEM-identified EIAs in all five Gulf Coast 

States. Figure 4-31 shows the aggregation of 133 counties and parishes that comprise the EIAs. 

Chapter 4.14.2 (Economic Factors) discusses the methodology behind the development of the EIAs 

and employment in the analysis area.

The U.S. Census Bureau’s calculations estimate that the total population of the combined 

BOEM economic impact areas exceeded 22.7 million in 2014. Figure 4-31 presents the range of 

population levels by county/parish across the GOM coastal region. County and parish population 

levels vary greatly across the coastal GOM. For example, Kenedy County, Texas, holds the low end 

of the range with 400 residents and Harris County, Texas, tops out the range at more than 

11,000 times that number (4,441,370). At the low end of the population spectrum, 42 (or nearly onethird) of 133 counties/parishes in BOEM’s EIAs have less than 25,000 residents. In the upper range, 

other counties with the >500,000 residents include Hillsborough County, Florida (1,316,298); 

Pinellas County, Florida (938,098); Hidalgo County, Texas (831,073); Fort Bend County, Texas 

(685,345); Lee County, Florida (679,513); Polk County, Florida (634,638); and Montgomery County, 

Texas (518,947) (USDOC, Census Bureau, 2014).

Population in the coastal regions of Gulf Coast States increased 150 percent from 1960 

through 2008 and continues to grow. There are 23 states in the U.S. with coastline populations, and 

the 5 Gulf Coast States occupy over 25 percent of the total for the coastal population of the U.S. Of 

the eight U.S. coastal counties with the fastest growth, six Gulf Coast counties posted the highest 

percentage of increase—from Lee County, Florida, at 1,091.5 percent to Collier County, Florida, at 

1,901.3 percent. In the nearly five decades from 1960 to 2008, the Gulf of Mexico coastal 

counties/parishes increased their populations by 246 percent, which is more than 52 percent greater 

than Pacific coastal counties (130%) and well over two-times as great as the Atlantic area (98%) 

(USDOC, Census Bureau, 2010a and 2010b; USDOC, NOAA, 2011).

Population density refers to the number of persons per square mile that live in a 

geographically defined area. In the GOM, the counties/parishes with the highest population density 

(persons per square mile) are Pinellas County, Florida (3,348); Harris County, Texas (2,402); 

Orleans Parish, Louisiana (2,029); Jefferson Parish, Louisiana (1,463); and Hillsborough County, 

Florida (1,205). Three of these top five counties/parishes have a high concentration of oil and gas 

industry in addition to hosting large cities: Harris County (Houston, Texas); and Orleans and 

Jefferson Parishes (Louisiana).
Description of the Affected Environment and Impact Analysis

4-421

Figure 4-31. Population of BOEM’s Economic Impact Areas in the Gulf of Mexico.
4-422 Gulf of Mexico Multisale EIS

Of all 133 counties/parishes in BOEM’s EIAs, Harris County, Texas, holds the largest 

number of oil- and gas-related companies and associated support infrastructure (Petterson et al., 

2008; Dismukes, 2011; Kaplan, et al., 2011). Additional counties and parishes with strong ties to the 

oil and gas industry include Galveston, Jefferson, Brazoria, and Nueces Counties, Texas; Jefferson, 

Plaquemines, Orleans, St. Bernard, Lafourche, Terrebonne, St. Mary, Vermilion, Cameron, and 

Calcasieu Parishes, Louisiana; Jackson County, Mississippi; and Mobile County, Alabama (Kaplan 

et al., 2011).

In the Gulf Coast region, the annual median household income at $41,203 is about 5 percent 

below the national average of $43,462 (USDOC, Census Bureau, 2010b). Figures 4-32 and 4-33

illustrate poverty levels across the GOM. Within the 133 counties/parishes that comprise BOEM’s

EIAs, 104 counties/parishes have residents living below the national average of 14.5 percent. The 

highest concentration of poverty is in TX-1 where 8 out of 11 counties have more than 30 percent of 

their population living below the national poverty level. Willacy County, Texas, has the highest 

poverty level (40%) and Fort Bend County, Texas, has the lowest poverty level (8.4%) (USDOC, 

Census Bureau, 2013a and 2013b).

Figure 4-32. Percentage of Poverty in Texas and Louisiana.
Description of the Affected Environment and Impact Analysis 4-423

Figure 4-33. Percentage of Poverty in Mississippi, Alabama, and Florida.

The average percentage of minority residents throughout the 23 BOEM-identified EIAs is 

22.9 percent, which is slightly below the national average of 26 percent. Forty-four 

counties/parishes have minority population levels above the national average. Figures 4-34 and 

4-35 illustrate the distribution of minority populations across the five Gulf Coast States. Orleans 

Parish, Louisiana, has the highest concentration of minority residents at 66.4 percent, while the 

lowest percentage is shared by two Texas counties, Kenedy and Zapata Counties, at 1.7 percent 

(USDOC, Census Bureau, 2013c).
4-424 Gulf of Mexico Multisale EIS

Figure 4-34. Percentage of Minority Populations in Texas and Louisiana.

Figure 4-35. Percentage of Minority Populations in Mississippi, Alabama, and Florida.

4.14.3.2 Environmental Consequences

A regionwide proposed lease sale is the preferred alternative and involves all of the Gulf 

Coast States, i.e., Texas, Louisiana, Mississippi, Alabama, and Florida. Particular emphasis is 

placed on the 133 counties and parishes that constitute the 23 BOEM-identified EIAs and that are 
Description of the Affected Environment and Impact Analysis 4-425

Routine activities related to a 

single lease sale would be 

incremental in nature, not 

expected to change existing 

conditions, and positive in its

contribution to the 

sustainability of current 

industry and related support 

services and employment. 

located in the coastal areas of all five states. Figure 4-27 shows the aggregation of counties and 

parishes into the EIAs used for BOEM’s socioeconomic analysis. This geographic area possesses a 

culturally and racially diverse population. Some counties and parishes are more closely connected 

to the offshore oil and gas industry than others. These include counties and parishes are Harris 

County, Texas, and Lafourche Parish, Louisiana. An analysis and discussion of the impactproducing factors from routine activities, accidental events (noncatastrophic), and cumulative 

activities can be found below. For a detailed analysis of a high-impact, low-probability catastrophic 

oil spill, refer to the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2016c).

Analysis of the various alternatives considers impact-producing factors within a distinct 

framework that includes frequency, duration, and geographic extent. Frequency (i.e., rare, 

intermittent, and continuous) refers to how often the impact-producing factor occurs over the entire 

analysis period of 50 years for routine activities and accidental events and for an analysis period of 

70 years for cumulative impacts. Duration (i.e., low, medium, and high) refers to how long the 

impact-producing factor lasts (i.e., from less than a year to many years). Geographic extent refers to 

which areas are affected and, depending on the impact-producing factor, the size of an affected 

area.

Routine Activities

People and communities are a major part of, and 

provide basic support for, the oil and gas industry. An analysis 

of the impacts of the industry’s routine activities (described in 

Chapter 3.1) on people and communities is complex because 

they are experienced at multiple levels that overlap, i.e., 

industry workers, families of workers, and the communities at 

large. Impacts occur in varying degrees of intensity. How 

communities as a whole and how families, workers, and other 

individuals are secondarily affected would vary depending on 

the industry sector and economic diversity of the communities in 

which they live. The interactions of industry and community are complex, resulting in a myriad of 

impacts, some positive and some negative. This complex relationship between industry and the 

community evolves over time, and the subsequent impacts evolve accordingly. Impact-producing 

factors related to routine activities can be experienced as positive or negative, depending on the 

specifics of any given situation, and cover a broad spectrum, i.e., employment stability, wages and 

opportunities for advancement, economic rewards in exchange for work (benefits), work scheduling 

patterns and how these dictate time spent off the job or with families, industry cycles and fluctuations 

in OCS oil- and gas-related activity levels, demographic shifts (in-migration and out- migration), 

commuter and truck traffic, commodity (oil/gas) price fluctuations, expansions of existing 

infrastructure, and new construction of infrastructure.

The oil and gas industry has evolved in the GOM for many decades, simultaneously affecting 

and being affected by the societal and economic conditions in the region. Because of this long-
4-426 Gulf of Mexico Multisale EIS

standing, complex interrelationship, the impacts of the oil and gas industry as a whole are diverse 

and widespread over many years. Austin et al. (2002) and Austin and McGuire (2002) describe this 

complexity from the viewpoint of workers and their families, and they found that impacts are 

experienced at many different levels and intensities depending on what sector of the industry is 

involved. For example, workers in the production sector enjoy more stable employment, while the 

drilling sector is volatile and provides less secure employment as it is more easily affected by 

fluctuations in oil and gas prices.

Employment stability in the oil and gas industry and its support sectors correlates directly 

with fluctuations in OCS oil- and gas-related activity levels, which are, in turn, closely related the 

changes in oil and gas commodity prices. Scott (2014) describes how important and influential the 

extraction, refining, and pipeline sectors of the oil and gas industry are for the State of Louisiana, 

from supporting over 287,000 jobs to paying nearly $1.5 billion in taxes to the State for 1 year alone. 

While the residents and communities of Louisiana enjoy unquestionable economic benefits, they 

also are most impacted by fluctuation in OCS oil- and gas-related activity levels and oil and gas 

prices. Petterson et al. (2008) describe how the benefits and burdens of the oil and gas industry are 

distributed unevenly across Texas, Louisiana, Mississippi, Alabama, and Florida, with some states 

(Texas and especially Louisiana) bearing the most burdens, while others accrue the benefits without 

suffering the burdens of hosting oil- and gas-related activities (e.g., Florida). This is further 

illustrated by Donato (2004) and Aratame and Singelmann (2002), who examine demographic shifts 

in Louisiana and the region related to the changing labor situation in the region, from the generally 

positive impact of immigrant workers to the commuting and migration trends from noncoastal to 

coastal communities following fluctuations in labor demand across the region.

The potential impacts resulting from the industry’s routine activities occur within the larger 

socioeconomic context of the GOM region. Given the existing, extensive, and widespread support 

system for the OCS oil- and gas-related industry and its associated labor force, the impacts of 

routine activities related to a single lease sale are expected to be negligible, widely distributed, and 

to have little impact. Routine activities related to a single lease sale would be incremental in nature, 

not expected to change existing conditions, and positive in their contribution to the sustainability of 

current industry, related support services, and associated employment.

Accidental Events

Accidental events related to OCS oil- and gas-related activities that could affect people and 

communities include oil spills, chemical/drilling-fluid spills, spill response, and vessel collisions. 

These events are described in Chapter 3.2. This section considers small-scale oil spills that have a 

greater probability of occurring. Potential oil spills, including surface spills and underwater well

blowouts, may be associated with exploration, production, or transportation phases of a proposed 

lease sale. A detailed risk analysis of offshore oil spills and coastal spills associated with a 

proposed lease sale can be found in Chapter 3.2.1. 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. 

Oil spills that occur in coastal or nearshore waters have a greater chance of directly affecting local 
Description of the Affected Environment and Impact Analysis 4-427

populations. Most small-scale oil spills are short in duration and have impacts ranging from 

negligible to moderate. Similarly, the impacts of chemical and drilling-fluid spills depend on the 

location of the spill, with closer to shore proximity increasing the likelihood of negative impacts, 

which can range from negligible to moderate, depending on the specific characteristics of the 

event. Vessel collisions also may affect local populations as they often result in oil or chemical spills 

and may interrupt transportation along waterways or roadways if a bridge is involved. Small-scale, 

noncatastrophic events involve varying degrees of spill response and containment. Spill-response 

activities are expected to have negligible to moderate impacts to people and communities, and 

these impacts also depend on the location and scale of the event being addressed. For example, if 

an accidental event is very small (not measurable) in size, affects a small geographic area, and is of 

short duration, its impact would be negligible. If an accidental event is measurable, covers a larger 

geographic area, and lasts a few days to a month, then its impact would be minor. If an accidental 

event affects a more than one county or parish, is measurable with impacts lasting up to 1 year, then 

the impact would be moderate. 

For a detailed discussion of a low-probability, catastrophic oil spill, refer to the Catastrophic 

Spill Event Analysis white paper (USDOI, BOEM, 2016c). Also, a BOEM-funded study (Austin et al., 

2014b and 2014c) researched and documented the complex and varied social impacts of the 

Deepwater Horizon explosion, oil spill, and response. This study found that the impacts of the spill 

on a particular community depended on a number of factors, such as social and political dynamics, 

proximity to the spill, economic structure, organizational structure for dealing with disasters, and 

ability to adapt to the oil cleanup and damage claims processes. With the exception of a 

catastrophic accidental event, such as the Deepwater Horizon explosion, oil spill, and response,

the impacts of oil spills, chemical/drilling-fluid spills, vessel collision, and spill-response activities are 

not or are not likely to be of sufficient duration to have adverse and disproportionate long-term 

impacts for people and communities in the analysis area.

Cumulative Impacts

People and communities experience cumulative impacts that include all human activities and 

natural processes and events. The cumulative analysis considers impacts that could result from a 

proposed lease sale combined with all past, present, and future OCS oil- and gas-related lease 

sales and activities, as well as all past, present, and reasonably foreseeable future actions that are 

external to OCS oil- and gas-related activities (described in Chapter 3.3). Within this divided 

analytical framework of OCS oil-and gas-related and non-OCS oil- and gas-related impacts, the 

largest quantity of impact-producing factors for people and communities occur as non-OCS oil- and 

gas-related impacts because OCS oil- and gas-related activities form such a small part of the 

greater, complex socioeconomic structure in the GOM, as described in the below sections.

OCS Oil- and Gas-Related Impacts

Potential impacts related to OCS oil- and gas-related activities include the OCS Program, 

consisting of 10 proposed lease sales in the GOM from 2017 to 2022, and the resultant exploration, 

development, and production in Federal waters that contribute to the following possible impacts 
4-428 Gulf of Mexico Multisale EIS

Non-OCS oil- and gas-related

factors are greater in number 

and actually contribute much

more to the cumulative 

impacts on people and 

communities than do factors 

related to OCS oil- and gasrelated activities because of 

the analysis area’s complex 

socioeconomic framework.

(Chapter 3.3.1): employment stability; wages and opportunities for advancement; economic 

rewards in exchange for work (benefits); work scheduling patterns and how these dictate time spent 

off the job or with families; industry cycles and fluctuations in OCS oil- and gas-related activity levels; 

demographic shifts (in-migration and out- migration); commuter and truck traffic; commodity (oil/gas) 

price fluctuations; expansions of existing infrastructure; new construction of infrastructure; coastal 

and offshore oil spills, chemical/drilling-fluid spills; spill-response activities; and vessel collisions. A 

proposed lease sale would make an incremental contribution to the cumulative impact of all past, 

present, and future lease sales.

For most of the GOM, the OCS Program would result in only minor economic changes. 

Generally, impacts would be widely yet thinly distributed across the Gulf Coast and would consist

of slight increases in employment and few, if any, increases in population. Some places could 

experience elevated employment, population, infrastructure, and/or traffic impacts because of local 

concentrations of fabrication and supply operations. Because of its extensive oil-related support

system, Louisiana is likely to experience more employment impacts related to a proposed lease 

sale than are the other coastal states. For example, Lafourche Parish, Louisiana, already 

services about 90 percent of all deepwater oil production and 45 percent of all shallow-water oil

and gas production in the Gulf, and it is likely to continue experiencing benefits from the OCS

Program (Scott, 2014). Except in Louisiana, the OCS Program is expected to provide little

additional employment, although it would serve to maintain current activity levels, which is

expected to be beneficial to the GOM as a whole.

With the exception of a catastrophic accidental event, such as the Deepwater Horizon

explosion, oil spill, and response, the impacts of oil spills, chemical/drilling-fluid spills, vessel 

collision, and spill-response activities are not or are not likely to be of sufficient duration to have 

adverse and disproportionate long-term impacts for people and communities in the analysis area 

(refer to Catastrophic Spill Event Analysis white paper, USDOI, BOEM, 2016c). Research into 

possible long-term health impacts of the Deepwater Horizon explosion, oil spill, and response is 

ongoing (National Institute of Environmental Health Science, 

2014; National Center for Disease Preparedness, 2013 and 

2014; Substance Abuse and Mental Health Services 

Administration and Centers for Disease Control and Prevention, 

2013).

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related impacts (described in 

Chapter 3.3.2) cover a wide range of potential impactproducing factors, including all human activities and natural

events and processes that are not related to OCS oil- and 

gas-related activities. Some of the human activities that may include people and communities

include, but are not limited to, the following: State-based and onshore oil and gas activities, 

commercial/residential/agricultural development; urbanization; pollution; zoning ordinances;
Description of the Affected Environment and Impact Analysis 4-429

expansions to the Federal, State, and local highway systems; expansions to regional port

facilities; demographic shifts; shifts on the national, State, and local levels; military activities;

government functions; educational systems; family support systems; public health; contraction or 

expansion of the tourism industry; State renewable energy activities; river channelization; and

dredging of waterways. 

State offshore oil and gas programs and onshore oil and gas activities pose the same 

potential issues as does the OCS Program, although since State leases are closer to land, their 

petroleum-related activities are generally viewed as having greater potential for directly impacting 

coastal communities. BOEM assumes that sitings of any future facilities associated with State

programs would be based on the same economic, logistical, zoning, and permitting considerations 

that determined past sitings. Revenues from oil programs in State waters have produced several

positive impacts, and the steady stream of oil exploration and development have produced 

positive cumulative impacts that include increased funding for infrastructure, higher incomes,

better health care, and improved educational facilities. This is certainly true for Texas, which has

historically used oil and gas revenues on State lands to equalize education district disparities across 

the State. While offshore leasing in shallow waters has been in a general decline, Louisiana is 

attempting to incentivize increased activity closer to the shore. In 2006, the Louisiana 

Legislature authorized the Louisiana Dept. of Environmental Quality to implement an Expedited

Processing Program, which has so far resulted in a 55 percent reduction in coastal permitting time 

(State of Louisiana, Dept. of Natural Resources, 2009).

Ongoing for decades, urbanization continues to impact people and communities, involving 

demographic shifts as people move into or out of the more densely populated areas. Impacts that 

result include strains on public infrastructure, habitat fragmentation, and reduced air and water 

quality, as well as the urban heat island effect. Closely related, but not limited to urban areas, are 

pollution impacts such as garbage dumping, air, light and noise pollution, and contaminated runoff, 

which also impact people and the communities in which they live. Zoning ordinances and land 

development, whether residential, commercial, or agricultural, can have negative and positive 

impacts on people, depending on how they stand to benefit or not from various proposed projects. 

When highway systems (whether local, State, or Federal) and port facilities are expanded, there is a 

tradeoff between the benefits of expansion and the potential negative impact to the local 

environment, people, and communities.

Economic conditions contribute to cumulative impacts on people and communities. When 

there is an economic downturn, some people lose their jobs and unemployment rises; people have 

less money to spend, causing a negative ripple effect through the local/regional/national economy as 

a result of direct, indirect, and induced economic impacts on communities. Military activities also 

contribute to cumulative impacts, whether through base closures that result in job losses or 

infrastructure expansion at military bases that may produce both positive (jobs) and negative (habitat 

loss) impacts.
4-430 Gulf of Mexico Multisale EIS

Other human activities that also have cumulative impacts on Gulf Coast populations are

related to local, State, and Federal government functions, which are numerous and expansive. Two 

of the more crucial government responsibilities for basic community functioning involve municipal

waterworks and sewage systems. If these are not maintained in good condition with adequate

capacity, negative impacts to the residents and community result. Similarly, the status of a 

community’s educational system may be a positive or negative benefit to these populations, 

depending on the quality of the educational facilities and infrastructure, the teacher-to-student

ratios, the standardized test scores, the amount and extent of busing across cities and towns, and 

the availability of special education services in the public schools (National Education 

Association, 2015; FSG Social Impact Consultants, 2011). Another very important non-OCS oiland gas-related impact-producing factor involves public health and family support services systems, 

namely their availability, proximity, and quality (CommonHealth ACTION, 2015). Social services 

such as public health clinics, mental health support, charity hospitals, addictive disorder

rehabilitation, foster care, head start programs, and family planning services are often hard to find in

rural areas, but these services may be more accessible in larger cities, towns, and urban areas.

Another important factor to consider is the contraction and expansion of the tourism 

industry, which is very important to the economies of the Gulf of Mexico region. When there is

a contraction in the tourism sector, the negative impacts are felt by all, whether directly or indirectly. 

BOEM funded a study (Eastern Research Group, Inc., 2014a) that developed methodologies for 

estimating the scales of recreation and tourism in a particular area. This entailed defining which 

industries comprise recreation and tourism, as well as estimating the percent of each industry that 

supports tourism. For example, the hotel industry is primarily supported by tourists, while the 

restaurant industry is supported by both tourists and local residents. Chapter 4.13 provides a 

complete discussion of tourism as a part of recreational resources. State renewable energy 

programs are non-OCS oil- and gas-related and may also contribute to cumulative impacts due to

their potential placement in areas that conflict with local uses, such as preferred fishing grounds. 

River channelization and dredging of other waterways also contribute to cumulative impacts for local 

populations, especially low- income and minority populations who may have traditionally fished and 

tended oyster beds negatively impacted by the disruption of the natural balance of the delicate 

ecosystem. 

While human activities are extensive and nearly all-encompassing, there are many natural

events and processes that may be classified as non-OCS oil- and gas-related impact-producing 

factors. Some of the natural events and processes that coastal populations may be affected by 

include, but are not limited to, the following: oyster reef degradation; saltwater intrusion; 

sedimentation of rivers; sediment deprivation; barrier island migration and erosion; fish kills; red

tide; coastal erosion/subsidence; sea-level rise; coastal storms; and climate change.

When degradation of oyster reefs occurs, it may negatively impact people and communities

by decreasing the number of oysters that are able to harvest for both economic and subsistence 

uses. Saltwater intrusion affects oyster reefs and the overall wetlands ecosystem. In some places

too much sediment is deposited in waterways, and in others there is sediment deprivation; both of 
Description of the Affected Environment and Impact Analysis 4-431

these negatively impact the delicate ecosystem upon which coastal populations depend. Barrier

islands are very important for fishing, but the barrier islands in the region have been migrating and 

eroding for decades. This natural process is one of the challenges faced in the region and 

contributes to cumulative impacts. Also, fish kills and red tide interfere with people’s use and 

enjoyment of the natural environment and contribute to negative cumulative impacts on GOM 

coastal populations.

Coastal erosion and subsidence in some parts of the southeastern coastal plain amplify the 

vulnerability of communities, infrastructure, and natural resources to storm-surge flooding (Dalton 

and Jones, 2010). Submergence in the GOM area is occurring most rapidly along the Louisiana 

coast and more slowly in other coastal states. Depending on local geologic conditions, the 

subsidence rate varies across coastal Louisiana from 3 to over 10 mm/yr (0.12 to over 0.39 in/yr). 

Natural drainage patterns along many areas of the Gulf Coast areas have been severely altered

by construction of the Gulf Intracoastal Waterway and other channelization projects associated

with its development. Saltwater intrusion resulting from land loss, river channelization, and canal

dredging is a major cause of coastal habitat deterioration (Tiner, 1984; National Wetlands 

Inventory Group, 1985; Cox et al., 1997). Coastal erosion, subsidence, sea-level rise, and storm 

surge damage can increase community vulnerability to future hazards and can also threaten

traditional ways of life. Saltwater intrusion reduces the productivity and species diversity

associated with wetlands and coastal marshes (Stutzenbaker and Weller, 1989; Cox et al., 1997). 

While users of coastal waters may appear to trend towards the relatively affluent, low-income and 

minority groups may be more dependent on the resources of the Gulf Coast. Several ethnic

minority and low-income groups rely substantially on these resources (e.g., refer to Hemmerling and 

Colten [2003] for an evaluation of environmental justice considerations for south Lafourche Parish).

Coastal land loss from erosion, subsidence, sea-level rise, and storm surge also affect the 

larger society as a whole, with significant land loss occurring in coastal areas, especially Louisiana, 

which has created a Coastal Master Plan focused on resolving the land loss crisis (State of 

Louisiana, Coastal Protection and Restoration Authority, 2012). This affects people and 

communities by impacting residential areas as well as local businesses and public infrastructure. 

Figure 4-28 shows the amount of land that coastal Louisiana has lost from 1932 to 2010. Figures 

4-29 and 4-30 illustrate scientists’ projections for future land loss in Louisiana. The moderate 

scenario assumes more mitigating measures, and the less optimistic scenario shows the projected 

impact if extensive mitigating measures are not instituted. As evident from these visual depictions, 

coastal land loss is one of the greatest threats to the stability and future of coastal populations. The 

Louisiana’s 2012 Coastal Master Plan captures the urgency of the land loss crisis: “Every day 

Louisiana citizens are affected by this catastrophe in ways small and large. Whether it’s a family 

forced to leave a cherished community to move out of harm’s way, a local businesses that has 

trouble obtaining insurance, or investments that lose value because of uncertainty about the future of 

our landscape, Louisiana’s land loss disaster takes a heavy toll” (State of Louisiana, Coastal 

Protection and Restoration Authority, 2012).
4-432 Gulf of Mexico Multisale EIS

A U.S. Geological Survey study published in 2013, Economic Vulnerability to Sea-Level Rise 

along the Northern U.S. Gulf Coast, applied a coastal economic vulnerability index (CEVI) to the 

northern Gulf coastal region in order to measure economic vulnerability to sea-level rise (Thatcher 

et al., 2013). The study attempted to determine which coastal communities may face the greatest 

challenges with regard to the economic and physical impacts of relative sea-level rise and revealed 

areas along the Gulf Coast that could most benefit from long-term resiliency planning. Within an 

area, the presence of a concentration of economically valuable infrastructure combined with physical 

vulnerability to inundation from sea-level rise resulted in the highest vulnerability rankings (CEVI 

score). The highest average CEVI score in the GOM coastal region appeared in Lafourche Parish, 

Louisiana, where there is an extensive amount of valuable infrastructure related to the oil and gas 

industry, along with high relative sea-level rise rates and high coastal erosion rates. Terrebonne 

Parish, Louisiana, also received a high CEVI value because of its high level of physical vulnerability 

and high concentration of energy infrastructure. Due to limitations within the CEVI model, such as

subjective weighting of variables, researchers caution that results of the study should remain 

within a vulnerability context and that CEVI results should only be considered relative measures

that are best utilized to provide decisionmakers with a better understanding of the vulnerability of 

the coastal region’s critical infrastructure when making decisions about modifying, protecting, or 

building new infrastructure in these coastal communities (Thatcher et al., 2013). 

Hurricanes, tropical storms, and other wind-driven tidal or storm events are a fact of life for 

communities living along the Gulf of Mexico coastal zone. The intensity and frequency of 

hurricanes in the GOM over the last several years has greatly impacted the system of protective 

barrier islands, beaches, and dunes and associated wetlands along the Gulf Coast. Within the last 

several years, the Gulf Coast of Texas, Louisiana, Mississippi, Alabama, and to some degree 

Florida have experienced five major hurricanes (Ivan, Katrina, Rita, Gustav, and Ike), as well as

minor hurricanes (Humberto and Isaac). According to a U.S. Geological Survey 5-year, postKatrina survey, the wetland loss in Louisiana from all four storms (i.e., Hurricanes Katrina, Rita, 

Gustav, and Ike) totaled 340 mi2

 (881 km2). The U.S. Geological Survey projects that coastal

Louisiana has undergone a net change in land area of about 1,883 mi2

 (4,877 km2) from 1932 to

2010 (Couvillion et al., 2011). Impacts from future hurricanes and tropical storm events are 

uncertain. Hazard mitigation funds available through individual states and the Federal Emergency 

Management Agency also seek to mitigate potential damage to homes in flood zones throughout 

the GOM. While hurricanes and tropical storms are inevitable, lessons learned from Hurricanes

Katrina, Rita, Gustav, and Ike are shaping local and national policies, as well as

nongovernmental organizations efforts to protect vulnerable communities. In the decade since 

Hurricanes Katrina and Rita, the New Orleans Metro Area has been recovering gradually, but 

unevenly. Population before the 2005 storms was 1.386 million, dropped to 1.040 million in 2006, 

and increased to 1.252 million in 2014. The number of grocery stores, pharmacies, and drug stores 

is still lower than 2005 numbers, but the number of gasoline stations, hotels, and restaurants have 

increased to greater than pre-storm levels (USDOC, Census Bureau, 2015; USDOC, Economics and 

Statistics Administration, 2015).
Description of the Affected Environment and Impact Analysis 4-433

Within the last few decades, climate change has become recognized as a serious issue. A 

study conducted by Elisaveta et al. (2015) focused on the impacts of climate change on the U.S. 

Gulf Coast and public health. The study found that numerous variables have contributed to the 

likelihood of extreme climate change impacts to the Gulf coastal region, including subsidence, 

severe erosion, changing water-use patterns, sea-level rise, storm surge, potential for large-scale 

industrial accidents, increasing population, and large numbers of vulnerable populations in the 

region. Climate change impacts may exacerbate existing public health issues and also create new 

health hazards. Identified climate change impacts include heat-related morbidity/mortality, droughtrelated malnutrition, flood-related injuries and death, increases in vector-borne diseases, and largescale migrations. The study suggests various public health adaptation measures such as the 

creation of educational programs and improved risk communication for vulnerable persons such as 

the elderly, minority, and low-income populations (Elisaveta et al., 2015).

Incomplete or Unavailable Information

BOEM has identified unavailable information that is relevant to people and communities 

regarding the impacts of the Deepwater Horizon explosion, oil spill, and response. This information 

cannot be obtained because long-term health impact studies, subsistence studies, and the NRDA 

process are ongoing, and data from these efforts would be unavailable and unobtainable for some 

time. In order to fill this data gap, BOEM has 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 a proposed lease sale and not likely expected to occur, may have adverse 

impacts on residents in GOM coastal communities. Research into possible long-term health impacts 

of the Deepwater Horizon explosion, oil spill, and response is ongoing (National Institute of 

Environmental Health Science, 2014; National Center for Disease Preparedness, 2013 and 2014; 

Substance Abuse and Mental Health Services Administration and Centers for Disease Control and 

Prevention, 2013). Because long-term health impacts to coastal populations are unknown, this 

information may be relevant to the evaluation of impacts from the Deepwater Horizon explosion, oil 

spill, and response; therefore, BOEM would continue to seek additional information as it becomes 

available and bases the previous analysis on the best information currently available. Although longterm health impacts to people and communities may be relevant to this analysis, BOEM has 

determined that the unavailable information is not essential to a reasoned choice among alternatives 

based on the information discussed above.

4.14.3.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred Alternative)

The potential impacts resulting from the industry’s routine activities occur within the larger 

socioeconomic context of the GOM region. Given the existing, extensive, and widespread support 

system for the OCS oil- and gas-related industry and its associated labor force, the impacts of 

routine events related to a proposed lease sale are expected to be negligible, widely distributed, 

and to have little impact. Routine activities related to a single lease sale would be incremental in 
4-434 Gulf of Mexico Multisale EIS

nature, not expected to change existing conditions, and positive in their contribution to the 

sustainability of current industry, related support services, and associated employment.

With the exception of a catastrophic accidental event, such as the Deepwater Horizon

explosion, oil spill, and response, the impacts of oil spills, chemical/drilling-fluid spills, vessel 

collision, and spill-response activities are not or are not likely to be of sufficient scale or duration to

have adverse and disproportionate long-term impacts for people and communities in the analysis 

area.

Coastal populations experience cumulative impacts that include all human activities and 

natural processes and events. The cumulative analysis includes impacts that could result from a 

proposed lease sale combined with all past, present, and future Federal OCS oil- and gas-related 

lease sales and activities, as well as all past, present, and reasonably foreseeable future actions that 

are external to Federal OCS oil- and gas-related activities. Within this divided analytical framework 

of OCS oil-and gas-related and non-OCS oil- and gas-related impacts, the largest quantity, by far, of 

impact-producing factors for coastal populations occur as non-OCS oil- and gas-related impacts 

because OCS oil- and gas-related activities form a very small part of the greater, complex 

socioeconomic structure in the GOM.

4.14.3.2.2 Alternative B—Regionwide OCS Lease Sale Excluding Available Unleased Blocks 

in the WPA Portion of the Proposed Lease Sale Area

Impacts for social factors are directly related to the level of OCS oil- and gas-related activity 

in the Gulf of Mexico. Alternative B would result in less OCS oil- and gas-related activity than 

Alternative A because the WPA (approximately 23 million ac) would not be available for leasing. 

Alternative A includes the WPA, CPA, and EPA. Alternative B includes the CPA and EPA. 

Therefore, Alternative B would produce proportionately smaller OCS oil- and gas-related activity 

than Alternative A, and the impacts of Alternative B would be proportionately less than Alternative A

but greater than Alternative C, as described below.

4.14.3.2.3 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the CPA/EPA Portions of the Proposed Lease Sale Area

Impacts for social factors are directly related to the level of OCS oil- and gas-related activity 

in the Gulf of Mexico. Alternative C would result in less OCS oil- and gas-related activity than 

Alternative A or B because the CPA and EPA (approximately 49 million ac) would not be available 

for leasing. Alternative A includes the WPA, CPA, and EPA, and Alternative B includes the CPA and 

EPA. In contrast, Alternative C includes only the WPA. Therefore, Alternative C would produce 

proportionately smaller OCS oil- and gas-related activity than Alternatives A and B, and the impacts 

of Alternative C would be proportionately less than either Alternative A or B.
Description of the Affected Environment and Impact Analysis 4-435

4.14.3.2.4 Alternative D—Alternative A, B, or C, with the Option to Exclude Available Unleased 

Blocks Subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or

Blocks South of Baldwin County, Alabama, Stipulations

Impacts for social factors are directly related to the level of OCS oil- and gas-related activity 

in the Gulf of Mexico. Alternative D would have minimal impact on social factors because there are 

so few unleased blocks subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations. The difference between Alternatives A, B, 

and C, with and without the exclusionary stipulations is negligible for social factors. The impacts 

under Alternative D would not be much different and likely not even measurable when compared 

with the other alternatives. To the extent that Alternative D would generate less OCS oil- and gasrelated activities due to the reduced number of blocks available for lease, the impacts of Alternative 

D would be less than Alternative A, B or C, but this difference would likely be indiscernible.

4.14.3.2.5 Alternative E—No Action

Alternative E would result in no lease sale and, thus, no incremental contribution of impacts 

to social factors beyond a potential negligible to minor negative economic impact on jobs because a 

single lease sale only contributes to the maintenance of existing employment. Any potential 

negative impact would be short lived and may not even be measurable.

4.14.3.3 Environmental Justice Determination

Executive Order 12898, “Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations,” directs Federal agencies to make a determination as to

whether their actions have disproportionate environmental impacts on minority or low- income

people. These environmental impacts encompass human health, and social and economic 

consequences. In 1997, President Clinton issued Executive Order 13045, “Protection of Children 

from Environmental Health Risks and Safety Risks,” requiring Federal agencies to identify and 

assess environmental health risks and safety risks of its policies, programs, and activities that

may disproportionately affect children. In accordance with NEPA and the Executive Orders,

BOEM provides opportunities for community input during the NEPA 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. The formal scoping process is initiated by 

the publication of a Notice of Intent, 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 5.3. A 

summary of the scoping comments for this Multisale EIS can be found in Chapter 5.3.1. 

When taken as a whole, environmental justice is a complex issue, but making an 

environmental justice determination is fairly straight-forward when considering OCS leasing 
4-436 Gulf of Mexico Multisale EIS

decisions. First, OCS lease sales occur in Federal waters 3 mi (5 km) or more from shore. Thus, 

the leaseholds and the permitted activities of petroleum exploration, extraction, and production that

occur on these leaseholds are distant from human habitation, and these activities would not have 

any impacts on low-income and minority populations. State offshore oil and gas leasing occurs in

waters closer to land were petroleum-related activities are generally viewed as having a greater

potential for directly impacting coastal communities. Second, this determination considers the

results of new lease sales. The OCS Program has been ongoing for many decades; it has already 

leased large areas in the Gulf of Mexico and, in this context, new lease sales mean only small,

incremental increases in the already substantial operations. Most OCS lease sale-related

consequences that might arise would be indirect, onshore, and would result from the operations 

of the extensive infrastructure system that exists to support not only OCS oil- and gas-related 

activities but also oil and gas activities that occur in State waters and onshore. The amount of 

Federal OCS contribution to downstream infrastructure use has not yet and, most likely, may never 

be discovered. Downstream infrastructure moves hydrocarbon product to market and includes gas 

processing facilities, petrochemical plants, transportation corridors, petroleum bulk storage 

facilities, and gas and petroleum pipelines. This infrastructure system is both widespread and 

concentrated (refer to Chapter 4.14.1). Much infrastructure is located in coastal Louisiana, less

in coastal Texas, and less still in Mississippi’s Jackson County and Alabama’s Mobile County. 

While many fabrication and supply facilities are concentrated around coastal ports, downstream 

processing is concentrated more in industrial corridors farther inland (Dismukes, 2011; Kaplan 

et al., 2011).

Potential environmental justice impacts that might arise from these support activities may 

be only indirectly influenced by BOEM’s decisionmaking, and BOEM has no regulatory authority 

over them. However, BOEM has considered the potential for these impacts on these communities. 

The onshore support activities that would result from a BOEM leasing decision occur in the 

context of a very large and long-established oil industry. For the most part, activities generated

by a new proposed lease sale occur where there are already ongoing activities, and the two (new 

activities vs. ongoing activities) are virtually indistinguishable from each other or from established

land-use patterns. Each industry sector and its associated impacts are often cumulative and 

occur within a mix of the impacts of other sectors in each geographic location. Therefore, BOEM 

has determined that a proposed lease sale would not adversely affect minority and low-income 

populations in the analysis area.

4.15 UNAVOIDABLE ADVERSE IMPACTS OF A PROPOSED ACTION

Unavoidable adverse impacts associated with a 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 a 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 
Description of the Affected Environment and Impact Analysis 4-437

involve the permanent or temporary use or “taking” of large areas of the OCS. 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 impacts from 

offshore engine combustion during routine operations would be accomplished through existing 

regulations and the development of new control emission technology. Short-term impacts from spill 

events could occur 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. Mitigation of impacts from these activities would be accomplished 

through existing NPDES regulations. 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 

nonpoint-source 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.

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.
4-438 Gulf of Mexico Multisale EIS

If an oil spill contacts coastal wetlands, adverse impacts could be high in localized areas. In 

more heavily oiled areas, wetland vegetation could experience suppressed productivity for several 

years; in more lightly oiled areas, wetland vegetation could experience die-back for one season. 

Epibionts (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 a proposed action.

Offshore Biological Habitats: Unavoidable adverse impacts would take place if an oil spill 

occurred and contacted offshore biological habitats, such as Sargassum 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.

Fish and Invertebrate Resources: Unavoidable adverse impacts from routine operations 

would take place from discharges from vessels and platforms. These would be 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 impacts on fish.

Birds: Unavoidable adverse impacts from routine operations on birds could result from 

noise, helicopter and OCS service-vessel traffic, coastal facility and platform lighting, and floating 

trash and debris. Trans-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 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. 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 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 impacts of the spill and also 

disruption from oil-spill cleanup activities.

Threatened and Endangered Species: Because a proposed 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 Multisale 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 
Description of the Affected Environment and Impact Analysis 4-439

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.

Marine Mammals: Unavoidable adverse impacts to 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 calving grounds.

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. If a large oil spill occurs, 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 Resources: 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 resources, 

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 resources 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 

resources 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 archaeological sites prior to an interaction occurring, thereby making avoidance 

or mitigation of impacts possible. A large oil spill that makes landfall on or near protected 

archaeological landmarks could cause loss of aesthetic value, contamination of material remains, 

loss of radiocarbon-dating potential, direct impacts from oil-spill cleanup activities, and/or looting.

Economic and Social Factors: 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 
4-440 Gulf of Mexico Multisale EIS

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.

4.16 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.

4.16.1 Coastal Habitats

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 dieback 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. Regulatory requirements of the State and Federal water authorities and some local 

jurisdictions would be applicable to these activities to mitigate these impacts. Ongoing natural and 

anthropogenic processes in the coastal zone, only one of which is an 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.

4.16.2 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.
Description of the Affected Environment and Impact Analysis 4-441

4.16.2.1 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.

4.16.2.2 Fish and Invertebrate Resources, Deepwater Benthic Communities, Commercial 

Fisheries, and Recreational Fishing

Irreversible loss of fish and invertebrate resources, including commercial and recreational 

species, are caused by structure removals 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. However, the Rigs-to-Reef 

Program would help offset these impacts.

4.16.3 Archaeological Resources

Irreversible loss of a prehistoric or historic archaeological resource can occur if bottomdisturbing 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.

4.16.4 Oil and Gas Development

Leasing and subsequent development and extraction of hydrocarbons as a result of a 

proposed action represents an irreversible and irretrievable commitment by the removal and 

consumption of nonrenewable oil and gas resources. The estimated amount of resources to be

recovered as a result of a proposed action is presented in Chapter 3.1. 

4.16.5 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, 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.
4-442 Gulf of Mexico Multisale EIS

4.17 RELATIONSHIP BETWEEN THE SHORT-TERM USE OF MAN’S ENVIRONMENT AND 

THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY

The short-term impacts on various components of the environment in the vicinity of the 

proposed action are related to long-term impacts and the maintenance and enhancement of longterm productivity.

4.17.1 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 a proposed action would provide 

short-term energy, and as it delays the increase in the Nation’s dependency on foreign imports, it 

can also allow additional time for ramp-up and development of long-term renewable energy sources 

or substitutes for nonrenewable oil and gas. Economic, political, and social benefits would accrue 

from the availability of these natural resources.

The principle short-term use of the leased areas in the Gulf of Mexico would be for the 

production of up to 0.211-1.118 BBO and 0.547-4.424 Tcf of gas from a proposed action. The 

cumulative impacts scenario in this Multisale EIS extends approximately from 2017 to 2066. The 

50-year time period is used because it is the approximate longest life span of activities conducted on 

an individual lease. The 50 years following a proposed lease sale is the period of time during which 

the activities and impacting factors that follow as a consequence of a proposed lease sale would be 

influencing the environment.

The specific impacts of a 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 a proposed action but also result in short-term, 

localized impacts. Activities during the production life of a platform may result in chronic impacts 

over a longer period of time (over 25 years), potentially punctuated by more severe impacts as a 

result of accidental events 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 impacts on physical, biological, and socioeconomic resources discussed in Chapter 4

are considered to be short term (being greatest during the construction, exploration, and early 

production phases). These impacts would be further reduced by the mitigating measures discussed 

in Chapter 2.2.4. 

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. 
Description of the Affected Environment and Impact Analysis 4-443

A 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, but this could be offset 

by the Rigs-to-Reef program.

The short-term exploitation of hydrocarbons for the OCS Program in the Gulf of Mexico may 

lead to long-term impacts on biologically sensitive 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 (refer to 

Chapter 4.14).

4.17.2 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 BSEE estimates that oil production in the GOM peaked at 1.6 MMbbl/day in 2002, declined for a 

few years and then peaked again in 2009 and 2010 at 1.6 MMbbl/day before declining again. 

Production rates in 2014 indicate it was another high year (1.4 MMbbl/day). Gas production in the 

GOM peaked at 14.4 Bcf/day in 1997 and has declined since to 3.4 Bcf/day in 2014. Production has 

shifted from many smaller reserves on the continental shelf to fewer larger reserves in deep water. 

Large deepwater oil discoveries have the potential to alter the oil production rate, but the exact effect 

any one discovery would have or when that discovery would be made is difficult to project due 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 the USEPA’s seven 
4-444 Gulf of Mexico Multisale EIS

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.

The Department of the Interior Mission

The Department of the Interior protects and manages the Nation’s natural 

resources and cultural heritage; provides scientific and other information 

about those resources; and honors the Nation’s trust responsibilities or 

special commitments to American Indians, Alaska Natives, and affiliated 

island communities.

The Bureau of Ocean Energy Management Mission

The Bureau of Ocean Energy Management (BOEM) is responsible for 

managing development of U.S. Outer Continental Shelf energy and mineral 

resources in an environmentally and economically responsible way.