U.S. Department of the Interior

Bureau of Ocean Energy Management 

Gulf of Mexico OCS Region 

OCS EIS/EA 

BOEM 2014-010 

Gulf of Mexico OCS 

Oil and Gas Lease Sales: 2015-2017 

Central Planning Area Lease Sales 235, 241, and 247 

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

Bureau of Ocean Energy Management 

Gulf of Mexico OCS Region 

OCS EIS/EA 

BOEM 2014-010 

Gulf of Mexico OCS 

Oil and Gas Lease Sales: 2015-2017 

Central Planning Area Lease Sales 235, 241, and 247 

Draft Supplemental Environmental Impact Statement 

Author 

Bureau of Ocean Energy Management 

Gulf of Mexico OCS Region 

Published by 

New Orleans

March 2014 



v 

COVER SHEET

Supplemental Environmental Impact Statement 

for 

Proposed OCS Oil and Gas Lease Sales 235, 241, and 247 

in the Central Planning Area of the Gulf of Mexico

Draft (x) Final ( ) 

Type of Action: Administrative (x) Legislative ( ) 

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

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

Poojan Tripathi (HM 3107) 

U.S. Department of the Interior

Bureau of Ocean Energy Management

381 Elden Street

Herndon, VA 20170-4817

(703) 787-1738

Brian Cameron

(504) 736-2990

Gary D. Goeke

(504) 736-3233

ABSTRACT

This Supplemental Environmental Impact Statement (EIS) addresses three proposed Federal actions: 

proposed Outer Continental Shelf (OCS) oil and gas Lease Sales 235, 241, and 247 in the Central

Planning Area (CPA) of the Gulf of Mexico, as scheduled in the Proposed Final Outer Continental Shelf 

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

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

natural gas leasing, exploration, development, and production in the CPA since publication of Gulf of 

Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western Planning Area Lease Sales 229, 233, 238, 

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

Impact Statement (2012-2017 WPA/CPA Multisale EIS) (USDOI, BOEM, 2012b) and Gulf of Mexico 

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

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

Supplemental EIS) (USDOI, BOEM, 2013a). This Supplemental EIS analyzes the potential impacts of a 

CPA proposed action on sensitive coastal environments, offshore marine resources, and socioeconomic 

resources both onshore and offshore. It is important to note that this Supplemental EIS was prepared 

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

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

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

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

information, accepted scientific methodologies were applied in its place.

The proposed actions are considered to be major Federal actions requiring an EIS. This document 

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

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

Supplemental EIS is the final NEPA review conducted for proposed CPA Lease Sale 235. A separate 

NEPA review will be conducted prior to BOEM’s decision on whether or how to proceed with proposed 

CPA Lease Sales 241 and 247. This document includes the purpose of and need for a CPA proposed 
vi

action, identification of the alternatives, description of the affected environment, and an analysis of the 

potential environmental impacts of a CPA proposed action, alternatives, and associated activities, 

including proposed mitigating measures and their potential effects. Potential contributions to cumulative 

impacts resulting from activities associated with the proposed actions are also analyzed.

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

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

disturbances associated with a CPA proposed action on biological, physical, and socioeconomic resources 

are considered in the analyses.

Additional copies of this Supplemental EIS, the 2012-2017 WPA/CPA Multisale EIS, the 

WPA 233/CPA 231 Supplemental 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 335A), 1201 Elmwood Park Boulevard, Room 250, New Orleans, Louisiana 70123-2394, by 

telephone at 504-736-2519 or 1-800-200-GULF, or on the Internet at http://boem.gov/EnvironmentalStewardship/Environmental-Assessment/NEPA/nepaprocess.aspx. 
Summary vii

SUMMARY

This Supplemental Environmental Impact Statement (EIS) addresses three proposed Federal actions 

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

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

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

sales are scheduled for the Central Planning Area (CPA). The remaining three proposed lease sales 

within the CPA are proposed CPA Lease Sales 235, 241, and 247, which are tentatively scheduled to be 

held in March 2015, 2016, and 2017, respectively. Federal regulations allow for several related or similar 

proposals to be analyzed in one EIS (40 CFR § 1502.4). Since each lease sale proposal and projected 

activities are very similar for the proposed CPA lease sale area, a single EIS is being prepared for the 

three remaining proposed CPA lease sales. At the completion of this EIS process, a decision will be made 

on whether or how to proceed with proposed CPA Lease Sale 235. A separate National Environmental 

Policy Act (NEPA) review, in a form to be determined by the Bureau of Ocean Energy Management 

(BOEM), will be conducted prior to BOEM’s decision on whether or how to proceed with proposed CPA 

Lease Sales 241 and 247. 

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

natural gas leasing, exploration, development, and production in the CPA since publication of Gulf of 

Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western Planning Area Lease Sales 229, 233, 238, 

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

Impact Statement (2012-2017 WPA/CPA Multisale EIS) (USDOI, BOEM, 2012b) and Gulf of Mexico 

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

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

Supplemental EIS) (USDOI, BOEM, 2013a). 

This Supplemental EIS analyzes the potential impacts of a CPA proposed action on sensitive coastal 

environments, offshore marine resources, and socioeconomic resources both onshore and offshore. It is 

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

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

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

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

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

methodologies were applied in its place.

This summary section provides only a brief overview of the proposed CPA lease sales, alternatives, 

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

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

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

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

EIS as described below.

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

proposed lease sales, the prelease process, postlease activities, and other OCS-related 

activities.

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

and socioeconomic effects of a proposed CPA lease sale and alternatives. Also 

discussed are potential mitigating measures to avoid or minimize impacts.

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

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

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

Gulf of Mexico.

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

describes offshore infrastructure and activities (impact-producing factors) 

associated with a proposed lease sale that could potentially affect the 

biological, physical, and socioeconomic resources of the Gulf of Mexico.
viii Central Planning Area Lease Sales 235, 241, and 247 EIS

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

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

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

a result of activities associated with a proposed lease sale.

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

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

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

socioeconomic resources of the Gulf of Mexico.

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

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

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

socioeconomic resources of the Gulf of Mexico.

Chapter 4.1, Proposed Central Planning Area Lease Sales 235, 241, and 

247, describes the routine, accidental, and cumulative impacts of a CPA 

proposed action and two alternatives to a CPA proposed action on the 

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

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

Proposed Actions; Chapter 4.3, Irreversible and Irretrievable Commitment 

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

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

Productivity.

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

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

parties that occurred during the development of this Supplemental EIS.

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

EIS.

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

for preparing and reviewing this Supplemental EIS.

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

Supplemental EIS.

• Appendix A, Air Quality Offshore Modeling Analysis, presents a detailed analysis of 

the Offshore Coastal Dispersion Model for air quality purposes.

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

catastrophic event to assist BOEM in meeting the Council on Environmental 

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

under NEPA. The CEQ regulations address impacts with catastrophic consequences 

in the context of evaluating reasonably foreseeable significant adverse effects in an 

EIS when they address the issue of incomplete or unavailable information (40 CFR § 

1502.22). For NEPA purposes, “‘[r]easonably foreseeable’ impacts include impacts 

that have catastrophic consequences even if their probability of occurrence is low, 

provided that the analysis of the impacts is supported by credible scientific evidence, 

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

1502.22(b)(4)). Therefore, this analysis, which is based on credible scientific 

evidence, identifies the most likely and most significant impacts from a high-volume 

blowout and oil spill that continues for an extended period of time. The scenario and 

impacts discussed in this analysis should not be confused with the scenario and 

impacts anticipated to result from routine activities or more reasonably foreseeable 

accidental events of a CPA proposed action.
Summary ix

• Appendix C, BOEM-OSRA Catastrophic Run, is a detailed explanation of BOEM’s 

Oil-Spill Risk Analysis (OSRA) and the computer model runs accomplished for this 

Supplemental EIS.

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

Mexico OCS Region, 2006-Present, contains a listing of publications that originated 

in BOEM’s (and the Agency’s predecessors, the Bureau of Ocean Energy 

Management, Regulation and Enforcement and the Minerals Management Service) 

Environmental Studies Program of the Gulf of Mexico OCS Region, with a particular 

focus on the most recent studies.

Proposed Action and Alternatives

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

Alternatives for Proposed Central Planning Area Lease Sales 235, 241, and 247 

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

all unleased blocks within the proposed CPA 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; 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.

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

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

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

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

66.45 million ac. As of February 2014, approximately 43.5 million ac of the proposed CPA lease sale 

area are currently unleased. The estimated amount of natural resources projected to be developed as a 

result of a proposed CPA lease sale is 0.460-0.894 billion barrels of oil (BBO) and 1.939-3.903 trillion 

cubic feet (Tcf) of gas (Table 3-1). 

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

Features: This alternative would offer for lease all unleased blocks within the proposed CPA lease sale 

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

blocks subject to the Topographic Features Stipulation. The estimated amount of resources projected to 

be developed is 0.460-0.894 BBO and 1.939-3.903 Tcf of gas (refer to Chapter 2.3.2 for further details).

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

alternative is chosen, the opportunity for development of the estimated 0.460-0.894 BBO and 

1.939-3.903 Tcf of gas that could have resulted from a proposed CPA lease sale would be precluded 

during the current 2012-2017 Five-Year Program, but it could again be contemplated as part of a future 

Five-Year Program. Any potential environmental impacts arising out of a proposed CPA lease sale 

would not occur, but activities associated with existing leases in the CPA would continue. This 

alternative is also analyzed in the Outer Continental Shelf Oil and Gas Leasing Program: 2012-2017, 

Final Environmental Impact Statement (Five-Year Program EIS) (USDOI, BOEM, 2012c) on a 

nationwide programmatic level.

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. Ten lease stipulations are proposed for a 

CPA proposed lease sale—the Topographic Features Stipulation; the Live Bottom (Pinnacle Trend) 

Stipulation; the Military Areas Stipulation; the Evacuation Stipulation; the Coordination Stipulation; the 
x Central Planning Area Lease Sales 235, 241, and 247 EIS

Blocks South of Baldwin County, Alabama, Stipulation; the Protected Species Stipulation; the Law of the 

Sea Convention Royalty Payment Stipulation; the Below Seabed Operations Stipulation; and the

Transboundary Stipulation. The Law of the Sea Convention Royalty Payment Stipulation is applicable to

proposed CPA lease sales even though it is not an environmental or military stipulation.

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

and Minerals (ASLM). The inclusion of the stipulations as part of the analysis of a CPA proposed action 

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

from a proposed lease sale, nor does it preclude minor modifications in wording during subsequent steps 

in the prelease process if comments indicate changes are necessary or if conditions warrant. Any lease 

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

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

enforceable as part of the lease.

Scenarios Analyzed

Offshore activities are described in the context of scenarios for a CPA 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 proposed CPA 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 CPA proposed action. The analyses are based on a 

traditionally employed range of activities (e.g., the installation of platforms, wells, and pipelines, and the 

number of helicopter operations and service-vessel trips) that would be needed to develop and produce 

the amount of resources estimated to be leased.

The cumulative analysis (Chapter 4.1.1) 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 activities such as import tankering and 

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

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

analysis period (2012-2051). This includes projected activity from lease sales that have been held, but for 

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

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

Significant Issues

The major issues that frame the environmental analyses in this Supplemental EIS, the 2012-2017 

WPA/CPA Multisale EIS, and the WPA 233/CPA 231 Supplemental EIS are the result of concerns raised 

during years of scoping for the Gulf of Mexico OCS Program. Issues related to OCS exploration, 

development, production, and transportation activities include the potential for oil spills, wetlands loss, air 

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

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

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

interference, cultural impacts, environmental justice, and conflicts with State coastal zone management

programs. Environmental resources and activities identified during the scoping process that warrant 

environmental analyses include air quality, water quality, coastal barrier beaches and associated dunes, 

wetlands, seagrass communities, live bottoms, topographic features, Sargassum communities, deepwater

benthic communities, soft bottom benthic communities, marine mammals, sea turtles, diamondback 

terrapins, beach mice, coastal and marine birds, Gulf sturgeon, fish resources and essential fish habitat, 

commercial fisheries, recreational fishing, recreational resources, archaeological resources, and 

socioeconomic conditions. 

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

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

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

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

environment (Chapter 4.1.1) includes impacts from these storms on the physical environment, biological 

environment, and socioeconomic activities and on OCS-related infrastructure. This Supplemental EIS 
Summary xi

also considers baseline data in the assessment of impacts from a CPA proposed action on the resources 

and the environment (Chapter 4.1.1). 

Impact Conclusions

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

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

described in Chapter 4.1.1. A summary of the potential impacts from a CPA proposed action on each 

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

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

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

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

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

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

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

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

associated with a CPA proposed action are not expected to occur at concentrations that would change 

onshore air quality classifications.

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

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

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

navigation canal maintenance, discharges of bilge and ballast water from support vessels, and run-off 

from shore-based facilities. Offshore water impacts associated with routine activities result from the 

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

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

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

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

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

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

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

Coastal Barrier Beaches and Associated Dunes: Routine activities associated with a CPA proposed 

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

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

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

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

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

CPA proposed action are anticipated to be minimal. Should a spill (other than a catastrophic spill) contact 

a barrier beach, oiling is expected to be light and sand removal during cleanup activities minimized. No 

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

are expected to occur as a result of a CPA proposed action.

Wetlands: Routine activities associated with a CPA proposed action are expected to be small, 

localized, and temporary due to the small length of projected onshore pipelines, the minimal contribution 

to the need for maintenance dredging, the disposal of OCS wastes, and the mitigating measures that 

would be used to further reduce these impacts. Indirect impacts from wake erosion and saltwater 

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

activities. The potential impacts from accidental events (primarily oil spills) are anticipated to be 

minimal. Overall, impacts to wetland habitats from an oil spill associated with activities related to a CPA 

proposed action would be expected to be small and temporary because of the nature of the system, 

regulations, and specific cleanup techniques.

Seagrass Communities: Turbidity impacts from pipeline installation and maintenance dredging 

associated with a CPA proposed action would be temporary and localized. The increment of impacts 

from service-vessel transit associated with a CPA proposed action would be minimal. Should an oil spill

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

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

equipment to clean up the spill would be needed to avoid or minimize those impacts.
xii Central Planning Area Lease Sales 235, 241, and 247 EIS

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

separation from sources of impacts as mandated by the Live Bottom (Pinnacle Trend) Stipulation and 

through site-specific seafloor reviews of proposed activity, and a community adapted to sedimentation 

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

In the unlikely event that oil from a subsurface spill would reach the biota of these communities, the 

effects would be primarily sublethal for adult sessile biota, and there would be limited incidences of 

mortality.

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

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

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

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

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

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

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

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

Sargassum Communities: The impacts that are associated with a CPA proposed action are expected 

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

of the Sargassum community could suffer mortality if it contacts spilled oil or cleanup activities. The 

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

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

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

proposed action.

Chemosynthetic and Nonchemosynthetic Deepwater Benthic Communities: Chemosynthetic and 

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

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

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

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

communities and, by consequence, avoidance of other hard bottom communities. Even in situations 

where substantial burial of typical benthic infaunal communities occurred, recolonization by populations 

from widespread, neighboring, soft bottom substrate would be expected over a relatively short period of 

time for all size ranges of organisms. Potential accidental events associated with a CPA proposed action 

are expected to cause little damage to the ecological function or biological productivity of the widespread, 

low-density chemosynthetic communities and the widespread, typical, deep-sea benthic communities.

Soft Bottom Benthic Communities: The routine activities associated with a CPA proposed action that 

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

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

areas of the soft bottom benthic communities would occur, the impacts would be on a relatively small 

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

; 

103,831 mi2

). A CPA proposed action is not expected to adversely impact the entire soft bottom 

environment because the local impacted areas are extremely small compared with the entire seafloor of 

the Gulf of Mexico and because the soft bottom benthic communities are ubiquitous throughout the Gulf 

of Mexico. 

Marine Mammals: Routine events related to a CPA proposed action are not expected to have adverse 

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

Mexico. Characteristics of impacts from accidental events depend on chronic or acute exposure from 

accidental events resulting in harassment, harm, or mortality to marine mammals, while exposure to 

dispersed hydrocarbons is likely to result in sublethal impacts.

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

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

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

associated with a CPA proposed action have the potential to impact small to large numbers of sea turtles. 

Populations of sea turtles in the northern Gulf of Mexico may be exposed to residuals of oils spilled as a 

result of a CPA proposed action during their lifetimes. While chronic or acute exposure from accidental 

events may result in the harassment, harm, or mortality to sea turtles, in the most likely scenarios, 

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

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

vulnerability to disease) to sea turtles. The incremental contribution of a CPA proposed action would not 

be likely to result in a significant incremental impact on sea turtles within the CPA; in comparison, nonOCS energy-related activities, such as overexploitation, commercial fishing, and pollution, have 

historically proved to be a greater threat to the sea turtle species.

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

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

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

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

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

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

CPA proposed action are not expected to impact terrapins or their habitat. The incremental effect of a 

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

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

overharvesting, crabbing, and fishing.

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

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

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

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

large-scale oiling of beach mice could result in extinction, and, if all personnel are not thoroughly trained, 

oil-spill response and cleanup activities could have a significant impact to the beach mice and their 

habitat.

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

CPA proposed action on threatened and endangered and nonthreatened and nonendangered avian species 

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

intake of OCS-related contaminants and discarded debris, disturbance-related impacts, and displacement 

of birds from habitats that are destroyed, altered, or fragmented, making these areas otherwise 

unavailable. Impacts from potential oil spills associated with a CPA proposed action and the effects 

related to oil-spill cleanup are expected to be adverse, but not significant. Oil spills, irrespective of size, 

can result in some mortality as well as sublethal, chronic short- and long-term effects, in addition to 

potential impacts to food resources. The effect of cumulative activities on coastal and marine birds is 

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

incremental contribution of a CPA proposed action to cumulative impacts is expected to be adverse, but 

not significant, because it may seriously alter avian species’ composition and abundance due to reductions 

in the overall carrying capacity of disturbed habitats, and possibly to the availability, abundance, and 

distribution of preferred food resources.

Gulf Sturgeon: Routine activities associated with a CPA proposed action, such as the installation of 

pipelines, maintenance dredging, potential vessel strikes, and nonpoint-source runoff from onshore 

facilities, would cause negligible impacts and would not deleteriously affect Gulf sturgeon. Indirect 

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

of inshore activities and are further reduced through mitigations and regulations. The potential impacts 

from accidental events, mainly oil spills associated with a CPA proposed action, are anticipated to be 

minimal. Because of the floating nature of oil, reduced toxicity through weathering (offshore dispersant

treatment) and the small tidal range of the Gulf of Mexico, oil spills alone would typically have very little 

impact on benthic feeders such as the Gulf sturgeon. The incremental contribution of a CPA proposed 

action to the cumulative impact is negligible.

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

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

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

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

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

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

activities associated with a CPA proposed action. Accidental events that could impact fish resources and 

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

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

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

particular essential fish habitats (e.g., nursery habitats), and the type and toxicity of oil spilled. Much of 
xiv Central Planning Area Lease Sales 235, 241, and 247 EIS

the sensitive essential fish habitat would have decreased effects from oil spills because of the depths many 

are found and because of the distance that these low-probability spills would occur from many of the 

essential fish habitats (due to stipulations, NTL’s, etc.). If there is an effect of an oil spill on fish 

resources in the Gulf of Mexico, it is expected to cause a minimal decrease in standing stocks of any 

population. This is because most spill events would be localized, therefore affecting a small portion of 

fish populations.

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

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

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

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

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

Commercial fishermen are anticipated to avoid the area of a well blowout or an oil spill. Large spills may 

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

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

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

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

fishermen during the initial phases of a CPA proposed action. A CPA proposed action could also lead to 

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

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

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

fishing closures in the vicinity of the oil spill. Except for a catastrophic spill such as the Deepwater

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

availability of substitute fishing sites in neighboring regions.

Recreational Resources: Routine OCS actions can cause minor disturbances to recreational 

resources, particularly beaches, through increased levels of noise, debris, and rig visibility. The oil spills

most likely to result from a CPA proposed action would be small, of short duration, and not likely to 

impact Gulf Coast recreational resources. Should an oil spill occur and contact a beach area or other 

recreational resource, it would cause some disruption during the impact and cleanup phases of the spill. 

However, except for a catastrophic spill such as the Deepwater Horizon oil spill, these effects are likely to 

be small in scale and of short duration.

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

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

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

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

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

required prior to an operator beginning oil and gas activities on a lease, are expected to be highly effective 

at identifying possible offshore archaeological sites; however, should such contact occur, there would be 

localized damage to or loss of significant and/or unique archaeological information. It is expected that 

coastal archaeological resources would be protected through the review and approval processes of the 

various Federal, State, and local agencies involved in permitting onshore activities.

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

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

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

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

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

sites would be visual contamination, which, while reversible, could result in additional impacts to fragile 

cultural materials from the cleaning process.

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

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

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

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

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

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

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

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

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

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

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

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

and distributions, as projected and described in Chapter 4.1.1.23, are expected to remain unchanged as a 

result of a CPA proposed action. The increase in employment is expected to be met primarily with the 

existing population and available labor force, with the exception of some in-migration (from elsewhere 

within or outside the U.S.), which is projected to move into focal areas such as Port Fourchon. 

Accidental events associated with a CPA proposed action, such as oil or chemical spills, blowouts, and 

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

communities.

Economic Factors: A CPA proposed action is expected to generate a <1 percent increase in 

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

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

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

Environmental Justice: Environmental justice implications arise indirectly from onshore activities 

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

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

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

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

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

of activity, which may or may not result in the expansion of existing infrastructure. For a detailed 

discussion of scenario projections and the potential for expansion at existing facilities and/or construction 

of new facilities, refer to Chapter 3.1.2. 

Table of Contents xvii

TABLE OF CONTENTS

Page

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

LIST OF FIGURES ................................................................................................................................... xxi

LIST OF TABLES...................................................................................................................................xxiii

ABBREVIATIONS aND ACRONYMS .................................................................................................. xxv

CONVERSION CHART .........................................................................................................................xxix

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

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

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

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

1.3.1. Recent BOEM/BSEE Rule Changes......................................................................... 1-6

1.3.1.1. Recent and Ongoing Regulatory Reform and GovernmentSponsored Research ................................................................................. 1-6

1.3.1.2. Recent and Ongoing Industry Reform and Research ............................... 1-7

1.4. Prelease Process....................................................................................................................... 1-7

1.5. Postlease Activities................................................................................................................ 1-10

1.6. Other OCS Oil- and Gas-Related Activities .......................................................................... 1-11

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

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

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

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

2.2.1.1. Alternatives for Proposed Central Planning Area Lease Sales 235, 

241, and 247............................................................................................. 2-4

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

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

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

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

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

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

2.3. Proposed Central Planning Area Lease Sales 235, 241, and 247............................................. 2-7

2.3.1. Alternative A—The Proposed Action (Preferred Alternative).................................. 2-7

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

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

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

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

2.3.1.3.2. Live Bottom (Pinnacle Trend) Stipulation .......................... 2-10

2.3.1.3.3. Military Areas Stipulation................................................... 2-10

2.3.1.3.4. Evacuation Stipulation ........................................................ 2-10

2.3.1.3.5. Coordination Stipulation ..................................................... 2-10

2.3.1.3.6. Blocks South of Baldwin County, Alabama, 

Stipulation ........................................................................... 2-11
xviii Central Planning Area Lease Sales 235, 241, and 247 EIS

2.3.1.3.7. Protected Species Stipulation .............................................. 2-11

2.3.1.3.8. Law of the Sea Convention Royalty Payment 

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

2.3.1.3.9. Below Seabed Operations Stipulation................................. 2-11

2.3.1.3.10. Transboundary Stipulation .................................................. 2-11

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

the Biologically Sensitive Topographic Features.................................................... 2-11

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

2.3.2.2. Summary of Impacts.............................................................................. 2-12

2.3.3. Alternative C—No Action....................................................................................... 2-12

2.3.3.1. Description............................................................................................. 2-12

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

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

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

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

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

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

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

3.1.1.2. Exploration and Delineation .................................................................... 3-6

3.1.1.2.1. Seismic Surveying Operations .............................................. 3-6

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

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

3.1.1.4. Operational Waste Discharged Offshore................................................ 3-10

3.1.1.5. Air Emissions......................................................................................... 3-10

3.1.1.6. Noise ...................................................................................................... 3-11

3.1.1.7. Major Sources of Oil Inputs in the Gulf of Mexico ............................... 3-11

3.1.1.8. Offshore Transport................................................................................. 3-12

3.1.1.9. Safety Issues........................................................................................... 3-12

3.1.1.10. Decommissioning and Removal Operations.......................................... 3-13

3.1.2. Coastal Impact- Producing Factors and Scenario.................................................... 3-13

3.1.2.1. Coastal Infrastructure ............................................................................. 3-13

3.1.2.2. Discharges and Wastes........................................................................... 3-14

3.2. Impact-Producing Factors and Scenario—Accidental Events............................................... 3-15

3.2.1. Oil Spills.................................................................................................................. 3-15

3.2.1.1. Spill Prevention...................................................................................... 3-15

3.2.1.2. Past OCS Spills...................................................................................... 3-15

3.2.1.3. Characteristics of OCS Oil..................................................................... 3-16

3.2.1.4. Overview of Spill Risk Analysis............................................................ 3-16

3.2.1.5. Risk Analysis for Offshore Spills ≥1,000 bbl ........................................ 3-17

3.2.1.6. Risk Analysis for Offshore Spills <1,000 bbl ........................................ 3-18

3.2.1.7. Risk Analysis for Coastal Spills............................................................. 3-18

3.2.1.8. Risk Analysis by Resource..................................................................... 3-19

3.2.1.9. Spill Response........................................................................................ 3-19

3.2.2. Losses of Well Control............................................................................................ 3-21

3.2.3. Pipeline Failures...................................................................................................... 3-22

3.2.4. Vessel Collisions..................................................................................................... 3-22

3.2.5. Chemical and Drilling-Fluid Spills ......................................................................... 3-22

3.3. Cumulative Activities Scenario ............................................................................................. 3-23

3.3.1. OCS Program .......................................................................................................... 3-23
Table of Contents xix

3.3.2. State Oil and Gas Activity....................................................................................... 3-24

3.3.3. Other Major Factors Influencing Offshore Environments ...................................... 3-25

3.3.3.1. Dredged Material Disposal .................................................................... 3-25

3.3.3.2. OCS Sand Borrowing............................................................................. 3-26

3.3.3.3. Marine Transportation............................................................................ 3-28

3.3.3.4. Military Activities.................................................................................. 3-28

3.3.3.5. Artificial Reefs and Rigs-to-Reefs Development................................... 3-28

3.3.3.6. Offshore Liquefied Natural Gas Projects and Deepwater Ports............. 3-29

3.3.3.7. Development of Gas Hydrates............................................................... 3-30

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

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

3.3.4.1. Sea-Level Rise and Subsidence ............................................................. 3-31

3.3.4.2. Mississippi River Hydromodification.................................................... 3-33

3.3.4.3. Maintenance Dredging and Federal Channels ....................................... 3-34

3.3.4.4. Coastal Restoration Programs................................................................ 3-36

3.3.5. Natural Events and Processes.................................................................................. 3-39

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

4.1. Proposed Central Planning Area Lease Sales 235, 241, and 247............................................. 4-3

4.1.1. Alternative A—The Proposed Action ....................................................................... 4-8

4.1.1.1. Air Quality ............................................................................................... 4-8

4.1.1.2. Water Quality......................................................................................... 4-17

4.1.1.2.1. Coastal Waters..................................................................... 4-17

4.1.1.2.2. Offshore Waters .................................................................. 4-23

4.1.1.3. Coastal Barrier Beaches and Associated Dunes..................................... 4-30

4.1.1.4. Wetlands................................................................................................. 4-38

4.1.1.5. Seagrass Communities........................................................................... 4-47

4.1.1.6. Live Bottoms (Pinnacle Trend and Low Relief).................................... 4-52

4.1.1.7. Topographic Features............................................................................. 4-59

4.1.1.8. Sargassum Communities........................................................................ 4-67

4.1.1.9. Chemosynthetic Deepwater Benthic Communities................................ 4-71

4.1.1.10. Nonchemosynthetic Deepwater Benthic Communities.......................... 4-78

4.1.1.11. Soft Bottom Benthic Communities........................................................ 4-83

4.1.1.12. Marine Mammals................................................................................... 4-92

4.1.1.13. Sea Turtles............................................................................................ 4-102

4.1.1.14. Diamondback Terrapins....................................................................... 4-113

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

Mice ..................................................................................................... 4-119

4.1.1.16. Coastal and Marine Birds..................................................................... 4-122

4.1.1.17. Gulf Sturgeon....................................................................................... 4-137

4.1.1.18. Fish Resources and Essential Fish Habitat........................................... 4-141

4.1.1.19. Commercial Fisheries........................................................................... 4-149

4.1.1.20. Recreational Fishing............................................................................. 4-157

4.1.1.21. Recreational Resources........................................................................ 4-161

4.1.1.22. Archaeological Resources.................................................................... 4-165

4.1.1.22.1. Historic .............................................................................. 4-165

4.1.1.22.2. Prehistoric.......................................................................... 4-172

4.1.1.23. Human Resources and Land Use ......................................................... 4-177

4.1.1.23.1. Land Use and Coastal Infrastructure ................................. 4-177

4.1.1.23.2. Demographics.................................................................... 4-188
xx Central Planning Area Lease Sales 235, 241, and 247 EIS

4.1.1.23.3. Economic Factors.............................................................. 4-191

4.1.1.23.4. Environmental Justice ....................................................... 4-194

4.1.1.24. Species Considered due to U.S. Fish and Wildlife Service 

Concerns............................................................................................... 4-208

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

Biologically Sensitive Topographic Features........................................................ 4-210

4.1.3. Alternative C—No Action..................................................................................... 4-212

4.2. Unavoidable Adverse Impacts of the Proposed Actions...................................................... 4-214

4.3. Irreversible and Irretrievable Commitment of Resources.................................................... 4-216

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

and Enhancement of Long-term Productivity...................................................................... 4-217

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

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

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

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

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

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

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

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

5.4. Distribution of the Draft Supplemental EIS for Review and Comment .................................. 5-6

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

5.6. Endangered Species Act........................................................................................................... 5-9

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

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

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

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

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

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

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

APPENDIX A. AIR QUALITY OFFSHORE MODELING ANALYSIS .............................................. A-3 

APPENDIX B. CATASTROPHIC SPILL EVENT ANALYSIS........................................................... B-iii

APPENDIX C. BOEM-OSRA CATASTROPHIC RUN ........................................................................ C-3 

APPENDIX D. RECENT PUBLICATIONS OF THE ENVIRONMENTAL STUDIES 

PROGRAM, GULF OF MEXICO OCS REGION, 2006-PRESENT............................ D-3 

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

LIST OF FIGURES

Page

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

Locations of Major Cities. .........................................................................................Figures-3

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

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

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

List of Tables xxiii

LIST OF TABLES

Page

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

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

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

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

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

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

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

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

Table 3-6. Annual Summary of Number and Total Volume of Oil Spilled into the Gulf of 

Mexico, 2001-2011 ..................................................................................................... Tables-7

Table 3-7. Waterway Length, Depth, Traffic, and Number of Trips for 2011.............................Tables-8

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

of Mexico during 2005-2012 .................................................................................... Tables-10

Table 3-9. Quantities of Dredged Materials Disposed of in Ocean Dredged-Material 

Disposal Sites between 2001 and 2010..................................................................... Tables-11

Table 3-10. Number of Vessel Calls at U.S. Gulf Ports Between 2002 and 2011 .......................Tables-12

Table 3-11. Corps of Engineers’ Galveston District Maintenance Dredging Activity for 

Federal Navigation Channels in Texas, 2001-2010 .................................................. Tables-13

Table 3-12. Corps of Engineers’ New Orleans District Maintenance Dredging Activity for 

Federal Navigation Channels in Louisiana, 2001-2010............................................ Tables-14

Table 3-13. Corps of Engineers’ Mobile District Maintenance Dredging Activity for 

Federal Navigation Channels in Mississippi, Alabama, and Florida, 2000-2010.....Tables-15

Table 4-1. Unusual Mortality Event Cetacean Data for the Northern Gulf of Mexico ..............Tables-16

Table 4-2. Economic Significance of Commercial Fishing 2011 .............................................. Tables-16

Table 4-3. Angler Trips in the Gulf of Mexico by Location and Mode from 2008 

through 2012 ............................................................................................................. Tables-17

Table 4-4. Fish Species Caught by Recreational Anglers from 2008 through 2012 ..................Tables-19

Table 4-5. Economic Impact of Recreational Fishing in the Gulf of Mexico in 2011 ...............Tables-20

Table 4-6. Employment in the Leisure/Hospitality Industry in Selected Geographic 

Regions ..................................................................................................................... Tables-21

Table 4-7. Peak Population Projected from Cumulative OCS Programs as a Percent 

of Total Population.................................................................................................... Tables-22

Table4-8. Baseline Population Projections (in thousands) by Economic Impact Area .............Tables-23

Table 4-9. Demographic and Employment Baseline Projections for Economic Impact 

Area AL-1 ................................................................................................................. Tables-25

Table 4-10. Demographic and Employment Baseline Projections for Economic Impact 

Area FL-1 .................................................................................................................. Tables-28

Table 4-11. Demographic and Employment Baseline Projections for Economic Impact 

Area FL-2 .................................................................................................................. Tables-31
xxiv Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-12. Demographic and Employment Baseline Projections for Economic Impact 

Area FL-3 .................................................................................................................. Tables-34

Table 4-13. Demographic and Employment Baseline Projections for Economic Impact 

Area FL-4 .................................................................................................................. Tables-37

Table 4-14. Demographic and Employment Baseline Projections for Economic Impact 

Area LA-1 ................................................................................................................. Tables-40

Table 4-15. Demographic and Employment Baseline Projections for Economic Impact 

Area LA-2 ................................................................................................................. Tables-43

Table 4-16. Demographic and Employment Baseline Projections for Economic Impact 

Area LA-3 ................................................................................................................. Tables-46

Table 4-17. Demographic and Employment Baseline Projections for Economic Impact 

Area LA-4 ................................................................................................................. Tables-49

Table 4-18. Demographic and Employment Baseline Projections for Economic Impact 

Area MS-1 ................................................................................................................. Tables-52

Table 4-19. Demographic and Employment Baseline Projections for Economic Impact 

Area TX-1 ................................................................................................................. Tables-55

Table 4-20. Demographic and Employment Baseline Projections for Economic Impact 

Area TX-2 ................................................................................................................. Tables-58

Table 4-21. Demographic and Employment Baseline Projections for Economic Impact 

Area TX-3 ................................................................................................................. Tables-61

Table 4-22. Peak Employment Projected from Cumulative OCS Programs as a Percent 

of Total Employment ................................................................................................ Tables-64

Table 4-23. Baseline Employment Projections (in thousands) by Economic Impact Area..........Tables-65

Table 4-24. Existing Coastal Infrastructure Related to OCS Activities in the Gulf of Mexico ...Tables-67

Table 4-25. Gulf of Mexico Counties and Parishes with Concentrated Levels of Oil- and 

Gas-Related Infrastructure ........................................................................................ Tables-67

Table 4-26. Deepwater Horizon Waste Landfill Destination....................................................... Tables-68
Abbreviations and Acronyms xxv 

ABBREVIATIONS AND ACRONYMS 

C degree Celsius 

F degree Fahrenheit 

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

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

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

 Final Environmental Impact Statement; Volumes I-III 

ac acre 

AEDP area evaluation and decision process 

Agreement Agreement between the United States of America and the United 

 Mexican States Concerning Transboundary Hydrocarbon Reservoirs 

 in the Gulf of Mexico 

AL Alabama 

API American Petroleum Institute 

ASLM Assistant Secretary of the Interior for Land and Minerals 

BAST best available and safest technology 

bbl barrel 

BBO billion barrels of oil 

BCR Bird Conservation Region 

BOEM Bureau of Ocean Energy Management 

BOEMRE Bureau of Ocean Energy Management, Regulation and Enforcement 

BOP blowout preventer 

BP British Petroleum 

BSEE Bureau of Safety and Environmental Enforcement 

CAA Clean Air Act of 1970 

CAAA Clean Air Act Amendments of 1990 

CAMx Comprehensive Air Quality Model with extensions 

CD Consistency Determination 

CEQ Council on Environmental Quality 

CEVI Coastal Economic Vulnerability Index 

CEWAF water-accommodated fractions plus COREXIT 9500 

CFR Code of Federal Regulations 

CG Coast Guard (also: USCG) 

CH4 methane 

CIAP Coastal Impact Assistance Program 

CMP Coastal Management Plans 

CO carbon monoxide 

CO2 carbon dioxide 

COE Corps of Engineers (U.S. Army) 

CPA Central Planning Area 

CSA Continental Shelf Associates 

CWPPRA Coastal Wetlands Planning, Protection and Restoration Act 

CZM Coastal Zone Management 

CZMA Coastal Zone Management Act 

DDE dichloro-diphenyldichloro-ethylene 

DOCD development operations coordination document 

DOD Department of Defense (U.S.) (also: USDOD) 

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

DPP development and production plan 

EA environmental assessment 

EFH essential fish habitat 

e.g. for example 

EIA Economic Impact Area 

EIS environmental impact statement 
xxvi Central Planning Area Lease Sales 235, 241, and 247 EIS

EP exploration plan

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

EPS exopolysaccharides

ERMA Environmental Response Management Application

ESA Endangered Species Act of 1973

ESP Environmental Studies Program 

ESPIS Environmental Studies Program Information System

et al. and others

et seq. and the following

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

2012-2017

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

Final Environmental Impact Statement

FL Florida

FPSO floating production, storage, and offloading system

FR Federal Register

ft feet

FWS Fish and Wildlife Service

G&G geological and geophysical

g gram 

gal gallon

GC-HARMS Gulf Coast Health Alliance: Health Risks Related to the Macondo Spill

GIWW Gulf Intracoastal Waterway

GMFMC Gulf of Mexico Fishery Management Council

GOM Gulf of Mexico

GS Geological Survey (also: USGS)

GuLF STUDY Gulf Long-Term Follow-Up Study

GWEI Gulfwide Emissions Inventory

H2S hydrogen sulfide

ha hectare

i.e. specifically

in inch

IPCC Intergovernmental Panel on Climate Change

JITF Joint Industry Task Force

kg kilogram

kg/d kilogram/day

km kilometer

L liter

LA Louisiana

LA Hwy 1 Louisiana Highway 1

LC50 lethal concentration to 50 percent

LCA Louisiana Coastal Area

LNG liquefied natural gas

m meter

MARPOL International Convention for the Prevention of Pollution from Ships

MCVAFF Mississippi Coalition for Vietnamese-American Fisher Folks and Families

mi mile

mm millimeter

MMbbl million barrels

MMcf million cubic feet

MMPA Marine Mammal Protection Act of 1972

MMS Minerals Management Service

MOA Memorandum of Agreement
Abbreviations and Acronyms xxvii

MODU mobile offshore drilling unit

MOU Memorandum of Understanding

MS Mississippi

N2O nitrous oxide

NAAQS National Ambient Air Quality Standards

NASA National Aeronautics and Space Administration

NEPA National Environmental Policy Act

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

NRC National Research Council

NRDA Natural Resource Damage Assessment

NTL Notice to Lessees and Operators

O3 ozone

OCD Offshore Coastal Dispersion

OCS Outer Continental Shelf

OCSLA Outer Continental Shelf Lands Act

OSAT Operational Science Advisory Team

OSHA Occupational Safety and Health Administration

OSRA Oil Spill Risk Analysis

P.L. Public Law

PAH polycyclic aromatic hydrocarbons 

PCB polychlorinated biphenyl

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

PM10 particulate matter less than or equal to 10 μm 

ppb parts per billion

ppm parts per million

PSD Prevention of Significant Deterioration

ROD Record of Decision

ROTAC Regional Operations Technology Assessment Committee

ROV remotely operated vehicle

RP Recommended Practice

RTR Rigs-to-Reefs 

SAV submerged aquatic vegetation

SCAT Shoreline Cleanup and Assessment Team

Secretary Secretary of the Interior 

SOx sulphur oxides

Stat. Statute

STOF-THPO Seminole Tribe of Florida-Tribal Historic Preservation Officer

sVGP Small Vessel General Permit

TA&R Technology Assessment and Research Program

Tcf trillion cubic feet

Trustee Council Natural Resource Damage Assessment Trustee Council

TX Texas

U.S. United States

U.S.C. United States Code

UME unusual mortality event

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

USDHS U.S. Department of Homeland Security
xxviii Central Planning Area Lease Sales 235, 241, and 247 EIS

USDOC U.S. Department of Commerce

USDOD U.S. Department of Defense (also: DOD)

USDOE U.S. Department of the Energy

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

USDOT U.S. Department of Transportation

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey (also: GS)

VGP Vessel General Permit

VOC volatile organic compound

VSP vertical seismic profiling

W. west

WAF water-accommodated fractions

WPA Western Planning Area

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

Supplemental EIS Western Planning Area Lease Sale 233; Central Planning Area 

Lease Sale 231, Final Supplemental Environmental Impact Statement

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

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

Final Environmental Impact Statement

yr year
Conversion Chart xxix

CONVERSION CHART

To convert from To Multiply by

millimeter (mm) inch (in) 0.03937

centimeter (cm) inch (in) 0.3937

meter (m) foot (ft) 3.281

kilometer (km) mile (mi) 0.6214

meter2 (m2) foot2 (ft2) 10.76

yard2 (yd2) 1.196

acre (ac) 0.0002471

hectare (ha) acre (ac) 2.47

kilometer2 (km2) mile2 (mi2) 0.3861

meter3 (m3) foot3 (ft3) 35.31

yard3 (yd3) 1.308

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

tonnes = 1 long ton or 2,200 pounds

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

CHAPTER 1 

THE PROPOSED ACTIONS

The Proposed Actions 1-3 

1. THE PROPOSED ACTIONS

1.1. PURPOSE OF AND NEED FOR THE PROPOSED ACTIONS

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

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

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

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

Lease Sales 235, 241, and 247 are tentatively scheduled to be held in March 2015, 2016, and 2017, 

respectively. 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 Outer Continental Shelf 

Lands Act (OCSLA) of 1953 (67 Stat. 462), as amended (43 U.S.C. §§ 1331 et seq.). The proposed CPA

lease sales will provide qualified bidders the opportunity to bid upon and lease acreage in the Gulf of 

Mexico OCS in order to explore, develop, and produce oil and natural gas. Under the OCSLA, for each 

potential lease sale in the Five-Year Program, the Bureau of Ocean Energy Management (BOEM) makes 

individual decisions on whether and how to proceed with a proposed lease sale. Although the analyses 

cover more than one proposed lease sale, this Supplemental EIS will be used by BOEM to support a 

decision on proposed CPA Lease Sale 235. Additional National Environmental Policy Act (NEPA) 

reviews, as appropriate, will be prepared prior to individual lease sale decisions on proposed CPA Lease 

Sales 241 and 247 to address any newly available significant information relevant to those proposed 

actions (refer to Chapter 2.1). Those NEPA reviews will tier from and incorporate by reference the 

analyses from previous lease sale EIS’s.

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

of Mexico constitutes one of the world’s major oil- and gas-producing areas and has proved a steady and 

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

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

the CPA would help reduce the Nation’s need for oil imports and lessen the dependence on foreign oil. 

The U.S. consumed 18.6 million barrels (MMbbl) of oil per day in 2012 (USDOE, Energy Information 

Administration, 2013a). The Energy Information Administration projects the total U.S. consumption of 

liquid fuels, including fossil fuels and biofuels, to remain at about 19.1 MMbbl of oil per day from 2013 

to 2040 (USDOE, Energy Information Administration, 2013b). Altogether, net imports of crude oil and 

petroleum products (imports minus exports) accounted for 45 percent of our total petroleum consumption 

in 2011. The U.S. crude oil imports stood at 8.4 MMbbl of oil per day in 2011. Petroleum product 

imports were 2.4 MMbbl of oil per day in 2011. Exports totaled 2.9 MMbbl of oil per day in 2011, 

mainly in the form of distillate fuel oil, petroleum coke, and residual fuel oil. In 2011, the Nation’s 

biggest supplier of crude oil and petroleum-product imports was Canada (29%), with countries in the 

Persian Gulf being the second largest source (22%) (USDOE, Energy Information Administration, 2012). 

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

tankering from sources overseas. Natural gas is not easily transported, making domestic production 

especially desirable. The need for domestic natural gas reserves is also based upon its use as an 

environmentally preferable alternative to oil for generating electricity.

This Supplemental EIS tiers from and incorporates by reference all of the relevant analyses from Gulf 

of Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western Planning Area Lease Sales 229, 233, 238, 

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

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

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

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

Supplemental EIS) (USDOI, BOEM, 2013a). The 2012-2017 WPA/CPA Multisale EIS notes that two 

sales may be held each year during the Five-Year Program—one in the WPA and one in the CPA.

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

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

publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. This 

Supplemental EIS analyzes the potential impacts of a CPA proposed action on the marine, coastal, and 

human environments. This Supplemental EIS will also assist decisionmakers in making informed, future 

decisions regarding the approval of operations, as well as leasing. At the completion of the NEPA
1-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

process, a decision will be made only for proposed CPA Lease Sale 235. A separate NEPA review, in a 

form to be determined by BOEM, will be conducted prior to BOEM’s decision on whether or how to 

proceed with proposed CPA Lease Sales 241 and 247. The analysis in this Supplemental EIS also 

focuses on the potential environmental effects of oil and natural gas leasing, exploration, development, 

and production in the areas identified through the Area Identification (Area ID) procedure as the proposed 

lease sale area. In addition to the No Action alternative (i.e., cancel a proposed lease sale), other 

alternatives are considered for a proposed CPA lease sale, such as deferring certain areas from a proposed 

lease sale.

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

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

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

resources in an environmentally and economically responsible way. The functions of BOEM include 

leasing, exploration and development, plan administration, environmental studies, NEPA analysis, 

resource evaluation, economic analysis, 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 and research, inspections, 

offshore regulatory programs, oil-spill response, and training and environmental compliance functions.

1.2. DESCRIPTION OF THE PROPOSED ACTIONS

The proposed actions are the next three oil and gas lease sales in the CPA as scheduled in the 

Five-Year Program. Federal regulations allow for several related or similar proposals to be analyzed in 

one EIS (40 CFR § 1502.4). Since the proposed CPA lease sales are in the same area and their projected 

activities are very similar, BOEM has decided to prepare a single Supplemental EIS for proposed CPA 

Lease Sales 235, 241, and 247. The analyses contained within this Supplemental EIS examine impacts 

from a single, typical CPA lease sale. The findings of these analyses can be applied individually to each 

of the proposed lease sales, i.e., proposed WPA Lease Sales 235, 241, and 247. While the impact 

analyses can be applied to each proposed lease sale, this Supplemental EIS is a decision document for 

only proposed CPA Lease Sale 235. Additional NEPA reviews will be conducted prior to individual 

decisions on proposed CPA Lease Sales 241 and 247 to address any newly available significant 

information relevant to those proposed actions (refer to Chapter 2.1). 

Proposed CPA Lease Sales 235, 241, and 247 are tentatively scheduled to be held in March 2015, 

2016, and 2017, respectively. The proposed CPA lease sale area encompasses about 63 million acres (ac)

of the total CPA area of 66.45 million ac. This area begins 3 nautical miles (nmi) (3.5 miles [mi]; 

5.6 kilometers [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 meters (m) (10,978 feet [ft]) (Figure 1-1). As of 

February 2014, approximately 43.5 million ac of the proposed CPA lease sale area are unleased.

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

(i.e., proposed CPA Lease Sale 235) is 0.460-0.894 billion barrels of oil (BBO) and 1.939-3.903 trillion 

cubic feet (Tcf) of gas. A proposed CPA lease sale includes proposed lease stipulations designed to 

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

and in Chapter 2.4.1.3 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS.

1.3. REGULATORY FRAMEWORK

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

(e.g., NEPA). Several Federal regulations establish specific consultation and coordination processes with 

Federal, State, and local agencies (e.g., Coastal Zone Management Act, Endangered Species Act, the 

Magnuson-Stevens Fishery Conservation and Management Act, and the Marine Mammal Protection Act). 

In addition, the OCS leasing process and all activities and operations on the OCS must comply with other 

applicable Federal, State, and local laws and regulations. A detailed list of the major, applicable Federal 

laws, regulations, and Executive Orders are listed below.
The Proposed Actions 1-5 

Regulation, Law, and Executive Order Citation

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

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

40 CFR parts 1500-1508

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

15 CFR part 930

Endangered Species Act of 1973 16 U.S.C. §§ 1631 et seq.

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

Essential Fish Habitat Consultation (in 1996 reauthorization of the 

Magnuson-Stevens Fishery Conservation and Management Act)

P.L. 94-265

16 U.S.C. §§ 1801-1891

50 CFR part 600 subpart K

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

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

40 CFR part 55

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

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

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

Executive Order 12777

Comprehensive Environmental Response, Compensation, and 

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

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

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

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

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

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

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

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

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

National Estuary Program P.L. 100-4

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

National Historic Preservation Act 16 U.S.C. §§ 470 et seq.

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

Occupational Safety and Health Act of 1970 29 U.S.C. §§ 651 et seq.

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

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

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

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

42 U.S.C. §§ 1996 and 1996a

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

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

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

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

Wilderness Act of 1964

P.L. 88-577

16 U.S.C. §§ 1131-1136

78 Stat. 890
1-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

Toxic Substances Control Act

P.L. 94-469

15 U.S.C. §§ 2601-2697

Stat. 2003

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

16 U.S.C. §§ 668-668d

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

Executive Order 12148 (7/20/79)

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

Executive Order 12608 (9/9/87)

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

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

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

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

Executive Order 13175: Consultation and Coordination with Indian 

Tribal Governments 65 FR 67249-67252 (2000)

Executive Order 13186: Responsibilities of Federal Agencies to 

Protect Migratory Birds 66 FR 3853 (2001)

1.3.1. Recent BOEM/BSEE Rule Changes

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

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

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

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

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

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

BOEM/BSEE rule changes, refer to Chapters 1.3 and 1.5 of the 2012-2017 WPA/CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS. 

1.3.1.1. Recent and Ongoing Regulatory Reform and Government-Sponsored 

Research

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

expressed in the various reports prepared following the Deepwater Horizon explosion, oil spill, and 

response. To date, regulatory reform has occurred through both prescriptive and performance-based 

regulation and guidance, as well as OCS safety and environmental protection requirements, as described 

in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The reforms 

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

improve workplace safety and to strengthen oil-spill prevention planning, containment, and response are 

described in detail in Chapter 1.3.1.2 of the 2012-2017 WPA/CPA Multisale EIS.

The “Oil and Gas and Sulphur Operations in the Outer Continental Shelf—Revisions to Safety and 

Environmental Management Systems” (SEMS II) Final Rule was completed in June 2013 (Federal 

Register, 2013a). This final rule, also known as the Workplace Safety Rule, includes refinements to the 

existing SEMS program. The SEMS II Rule amends the existing regulations to require operators to 

develop and implement additional provisions involving stop work authority and ultimate work authority, 

establishes requirements for reporting unsafe working conditions, and requires employee participation in 

the development and implementation of their SEMS programs. In addition, the final rule requires the use 

of independent third parties to perform the audits of the operators’ programs.

The SEMS II Rule provides greater protection by supplementing operators’ SEMS programs with 

employee training, empowering field level personnel with safety management decisions, and 

strengthening auditing procedures by requiring them to be environmental management systems. The 

SEMS is a nontraditional, performance-focused tool for integrating and managing offshore operations. 

The purpose of SEMS is to enhance the safety of operations by reducing the frequency and severity of 

accidents. There are four principal SEMS objectives:
The Proposed Actions 1-7 

(1) focus attention on the influences that human error and poor organization have on 

accidents;

(2) continuous improvement in the offshore industry’s safety and environmental records;

(3) encourage the use of performance-based operating practices; and

(4) collaborate with industry in efforts that promote the public interests of offshore 

worker safety and environmental protection (Federal Register, 2013a).

In addition, on April 30, 2013, BSEE and the U.S. Coast Guard (USCG) entered into a Memorandum 

of Agreement (MOA) entitled “Safety and Environmental Management Systems (SEMS) and Safety 

Management Systems (SMS).” The purpose of this MOA is to

• establish a process to determine areas relevant to safety and environmental 

management within the jurisdiction of both the USCG and BSEE where joint policy 

or guidance is needed;

• ensure that any future OCS safety and environmental management regulations do not 

place inconsistent requirements on industry; and

• establish a process to develop joint policy or guidance on safety and environmental 

management systems (Federal Register, 2013a).

1.3.1.2. Recent and Ongoing Industry Reform and Research

Shortly after the Deepwater Horizon explosion, oil spill, and response, various industry trade 

associations formed four Joint Industry Task Forces (JITF’s) to learn from the Deepwater Horizon

explosion, oil spill, and response and to advance industry practices. The JITF’s are comprised of member 

companies and affiliates of the American Petroleum Institute (API), the International Association of 

Drilling Contractors, Independent Petroleum Association of America, National Ocean Industries 

Association, and U.S. Oil and Gas Association. The ultimate objectives of the JITF’s are to reduce risk 

and to improve the industry’s capabilities in safety, environmental performance, and spill prevention and 

response. Chapter 1.3.1.3 of the 2012-2017 WPA/CPA Multisale EIS describes in detail the 

recommendations from the JITF’s that have led to the reform of industry standards, recommended 

practices, and guidelines.

In March 2013, the API completed Recommended Practice (RP) 96: “Deepwater Well Design and 

Construction” (API, 2013a). This standard provides well design and operational considerations for the 

safe construction of a deepwater well, including the drilling and completion activity performed with a 

subsea blowout preventer (BOP), a marine drilling riser, and a subsea wellhead.

The API also completed Balloted Bulletin 97: “Well Construction Interface Document Guidelines” in 

May 2013 (API, 2013b). These guidelines aim to meet DOI’s objective by being a bridging document 

between the drilling contractor’s Health, Safety, and Environmental safety case and the operator’s SEMS, 

and they will address safety and risk management considerations on a well-by-well basis.

1.4. PRELEASE PROCESS

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

Quality’s (CEQ) guidelines on implementing NEPA. Scoping provides those with an interest in the OCS 

Program an opportunity to provide comments on the proposed actions. In addition, scoping provides 

BOEM an opportunity to update the Gulf of Mexico OCS Region’s environmental and socioeconomic 

information base. BOEM conducted early coordination with appropriate Federal and State agencies and 

other concerned parties to discuss and coordinate the prelease process for proposed CPA Lease Sales 235, 

241, and 247 and for this Supplemental EIS. While scoping is an ongoing process, it officially 

commenced on August 23, 2013, with the publication of the Notice of Intent to Prepare an EIS (NOI) in 

the Federal Register (2013b). Additional public notices were distributed via local newspapers, the U.S. 

Postal Service, and the Internet. A 30-day comment period was provided; it closed on September 23, 

2013. Federal, State, and local governments, along with other interested parties, were invited to send 
1-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

written comments to the Gulf of Mexico OCS Region on the scope of this Supplemental EIS. Comments 

were received in response to the NOI from Federal, State, and local government agencies; interest groups; 

industry; businesses; and the general public on the scope of this Supplemental EIS, significant issues that 

should be addressed, alternatives that should be considered, and mitigating measures. All scoping 

comments received were considered in the preparation of the Draft Supplemental EIS. The comments 

have been summarized in Chapter 5.3, “Development of the Draft Supplemental EIS.”

On October 24, 2012, BOEM released its Area ID decision. The Area ID is an administrative 

prelease step that describes the geographical area of the proposed actions (proposed lease sale area) and 

identifies the alternatives, mitigating measures, and issues to be analyzed in the appropriate NEPA

document. As mandated by NEPA, this Supplemental EIS analyzes the potential impacts of the CPA

proposed actions on the marine, coastal, and human environments.

BOEM will mail copies of the Draft Supplemental EIS for review and comment to Federal, State, and 

local government agencies; interest groups; industry; the general public; and local libraries. To initiate 

the public review and comment period on the Draft Supplemental EIS, BOEM will publish a Notice of 

Availability (NOA) in the Federal Register. In addition, public notices will be mailed with the Draft 

Supplemental EIS and will be placed on BOEM’s Internet website (http://www.boem.gov/EnvironmentalStewardship/Environmental-Assessment/NEPA/nepaprocess.aspx).

A consistency review will be performed in accordance with the Coastal Zone Management Act 

(CZMA), and a Consistency Determination (CD) will be prepared for each affected State prior to each 

proposed CPA lease sale. To prepare the CD’s, BOEM reviews each State’s Coastal Management 

Program (CMP) and analyzes the potential impacts as outlined in this Supplemental EIS, new 

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

analyses, BOEM’s Director makes an assessment of consistency, which is then sent to each State with the 

Proposed Notice of Sale (NOS). If a State disagrees with the Bureau of Ocean Energy Management’s 

CD, the State is required to do the following under the CZMA: (1) indicate how BOEM’s presale 

proposal is inconsistent with its CMP; (2) suggest alternative measures to bring BOEM’s proposal into 

consistency with their CMP; or (3) describe the need for additional information that would allow a 

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

not a procedure for administrative appeal to the Secretary of Commerce for a Federal CD for presale 

activities. In the event of a disagreement between a Federal agency and the State’s CMP regarding 

consistency of the proposed lease sales, either BOEM or the State may request mediation. The 

regulations provide for an opportunity to resolve any differences with the State, but the CZMA allows 

BOEM to proceed with a proposed lease sale despite any unresolved disagreements if the Federal agency 

clearly describes to the State’s CMP, in writing, how the activity is consistent to the maximum extent 

practicable with the State’s CMP. 

Prior to proposed CPA Lease Sale 235, which is tentatively scheduled for March 2015, and the Final 

Supplemental EIS, BOEM will publish an NOA in the Federal Register. BOEM will send copies of the 

Final Supplemental EIS to Federal, State, and local agencies; interest groups; industry; the general public; 

and local libraries. In addition, public notices will be mailed with the Final Supplemental EIS and will be 

placed on BOEM’s Internet website (http://www.boem.gov/Environmental-Stewardship/EnvironmentalAssessment/NEPA/nepaprocess.aspx). At the completion of this EIS process, a decision will be made for 

proposed CPA Lease Sale 235. A separate NEPA review will be conducted prior to proposed CPA Lease 

Sales 241 and 247.

The Final Supplemental EIS is not a decision document. The Assistant Secretary of the Interior for 

Land and Minerals Management (ASLM) will make and announce the decision on whether to hold each 

lease sale (i.e., one each for proposed CPA Lease Sales 235, 241 and 247) and the particulars of the lease 

sale if it is to be held, such as mitigations that will be imposed as part of the lease sale. A NEPA Record 

of Decision (ROD) will memorialize the decision and will identify BOEM’s preferred alternative for each 

lease sale, as well as the environmentally preferable alternative, if different. The ROD will summarize 

the proposed action and the alternatives evaluated in this Supplemental EIS, the information considered in 

reaching the decision, and the adopted mitigations.

A Proposed NOS will become available to the public 4-5 months prior to each proposed lease sale. A 

notice announcing the availability of the Proposed NOS appears in the Federal Register, initiating a 

60-day comment period. Comments received will be analyzed during preparation of the decision 

documents that are the basis for the Final NOS, including lease sale configuration and terms and 

conditions.
The Proposed Actions 1-9 

If the decision by the ASLM is to hold a proposed lease sale, a Final NOS will be published in its 

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

Measures to Enhance Transparency and Effectiveness in the Leasing and Tiering Process

The following discussion is from the Five-Year Program EIS and has been incorporated into this 

Supplemental EIS for information purposes.

BOEM realizes that each region is different in terms of mineral resources and dependent economies, 

the relative state of infrastructure and support industries, and the sensitivity of ecosystems, environmental 

resources, and communities; and that a leasing strategy needs to be sensitive to those differences, but also 

that it must be consistent with OCSLA principles. BOEM envisions a phased OCSLA process that 

minimizes multiple-use and environmental conflicts to the extent possible during the Five-Year Program 

implementation, that makes lease sale decisions in the context of the best available information, and that 

discloses clear reasons for those decisions, even in the face of uncertainty. This vision is consistent with 

the National Ocean Policy Implementation Plan and related Marine Planning initiatives, all of which 

provide a complementary framework for space-use conflict considerations. 

BOEM is committing to several process enhancements to ensure transparency during the phased 

OCSLA and tiered NEPA processes of this Five-Year Program. Although specific approaches to 

implementation may be tailored to the different needs of the Regions and their stakeholders, BOEM is 

determined to improve the effectiveness of the tiering process (40 CFR § 1508.28) through the following: 

• Alternative and Mitigation Tracking Table. BOEM has established an alternative 

and mitigation tracking table to provide increased visibility into the consideration of 

recommendations for deferrals, mitigations, and alternatives at different stages of the 

leasing process. Beginning with the Five-Year Program EIS, the table tracks the 

lineage and treatment of suggestions for spatial exclusions, temporal deferrals, and/or 

mitigation from the Five-Year Program, to the lease sale phase, and on to the plan 

phase. This table allows commenters to see how and at what stage of the process 

their concerns are being considered. BOEM will maintain a table that will be 

updated as deferral requests are considered at the lease sale and plan stages and as 

new requests are made. The alternative and mitigation tracking table has been placed 

on BOEM’s website at http://www.boem.gov/5-year/2012-2017/Tracking-Table/. A 

link to the table will be provided in the lease sale documents and in the annual report, 

which is discussed below.

• Strengthening the Prelease Sale Process. BOEM is taking a number of steps to 

enhance opportunities for members of the public to comment and provide new 

information in the prelease sale planning process. Historically, the Call for 

Information (Call), which is the first step in the Prelease Sale Process, has generally 

asked for industry to nominate specific blocks or descriptions of areas within the 

Five-Year Program area for which they have the most interest. The NOI requests 

comments from other Federal, State, and local governments, nongovernmental 

organizations, and the general public on issues that should be addressed and 

alternatives that should be considered in the NEPA documents that will be prepared 

for the action.

• Annual Progress Report. BOEM will publish an annual progress report on the 

approved Five-Year Program that includes an opportunity for stakeholders and the 

public to comment on the Five-Year Program’s implementation. Under Section 18(e) 

of the OCSLA, the Secretary must review annually the approved Five-Year Program. 

Historically, this has been an internal review process that reported to the Secretary 

any information or events that might result in a revision to the Five-Year Program. If 

the revision is considered significant under the OCSLA, the Five-Year Program can 

only be revised and reapproved by following the same Section 18 steps used to 

originally develop the Program. However, once the Section 18 process has been 

initiated for the next Five-Year Program, the annual review is subsumed in that 

process, as the same substantive and procedural requirements are being addressed.
1-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

The findings of this progress report may lead the Secretary to revise the Five-Year 

Program by reducing the size of, delaying, or canceling scheduled lease sales. If the 

desired revisions are considered significant, such as including new areas for 

consideration or more lease sales in areas already included, the entire Section 18 

process must be followed, in essence resulting in the preparation of a new Program.

• Systematic Planning. BOEM is committed to engaging in systematic planning 

opportunities that foster improved governmental coordination, communication, and 

information exchange. As the only agency authorized to grant renewable energy, 

marine mineral, and oil and gas leases on the OCS, the Bureau of Ocean Energy 

Management has been assigned the Federal co-lead, along with the U.S. Coast Guard, 

for systematic regional planning efforts in the Mid-Atlantic. Additionally, BOEM 

will participate on Regional Planning Bodies in the Northeast, Mid-Atlantic, and 

West Coast as the DOI lead. In the Gulf of Mexico OCS Region, BOEM 

representatives will assist the U.S. Fish and Wildlife Service (FWS), the DOI 

regional lead, with various working group activities. This will facilitate data and 

information availability, provide research of new technologies, and identify conflict 

resolution and avoidance strategies. BOEM anticipates that its Marine Planning 

engagement will enhance regulatory efficiency through improved coordination and 

collaboration, and, in the long term, enhance the stewardship of ocean and coastal 

resources.

These strategies will allow BOEM to not only address the activities that take place under the 

2012-2017 Five-Year Program but also to lay the groundwork for decisions that will be faced in 

subsequent Five-Year Programs. BOEM will improve efforts to gather information while enhancing 

opportunities for stakeholders and other interested parties to participate in and be engaged in the 

decisionmaking process. The initiation of studies and long-term planning will facilitate future decisions 

by ensuring that the best information is available when making leasing decisions on the approved 

program and before the development of future OCS Programs.

1.5. POSTLEASE ACTIVITIES

BOEM and BSEE are responsible for managing, regulating, and monitoring oil and natural gas 

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

development of mineral resources and to prevent harm or damage to, or waste of, any natural resource, 

any life or property, or the marine, coastal, or human environment. Regulations for oil, gas, and sulphur 

lease operations are specified in 30 CFR parts 250, 550, 551 (except those aspects that pertain to drilling), 

and 554.

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

implemented through lease stipulations, operating regulations, and project-specific requirements or 

approval conditions. Notices to Lessees and Operators (NTL’s) provide clarifications and additional 

information on some of these measures. Mitigating measures address concerns such as endangered and 

threatened species, geologic and manmade hazards, military warning and ordnance disposal areas, 

archaeological sites, air quality, oil-spill response planning, chemosynthetic communities, artificial reefs, 

operations in hydrogen sulfide (H2S) prone areas, and shunting of drill effluents in the vicinity of 

biologically sensitive features. Standard mitigating measures in the Gulf of Mexico OCS may include the 

following:

• limiting the size of explosive charges used for structure removals (NTL 2010-G05);

• requiring placement of explosive charges at least 15 ft (5 m) below the mudline;

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

nets upon abandonment;

• establishment of No Activity and Modified Activity Zones around high-relief live 

bottoms; 
The Proposed Actions 1-11

• requiring remote-sensing surveys to detect and avoid potential archaeological sites 

and biologically sensitive areas such as low-relief live bottoms, pinnacles, and 

chemosynthetic communities; and

• requiring coordination with the military to prevent multiuse conflicts between OCS 

and military activities.

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

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

administrative information. A detailed listing of current Gulf of Mexico OCS Region NTL’s is available 

through BOEM’s Gulf of Mexico OCS Region’s Internet website at http://boem.gov/Regulations/NoticesLetters-and-Information-to-Lessees-and-Operators.aspx or through the Region’s Public Information 

Office at (504) 736-2519 or 1-800-200-GULF.

Formal plans must be submitted to BOEM for review and approval before any project-specific 

activities, except for ancillary activities (such as geological and geophysical [G&G] activities or studies 

that model potential oil and hazardous substance spills), can begin on a lease. Conditions of approval, 

which are mechanisms to control or mitigate potential safety or environmental problems associated with 

proposed operations, must be met before the activities can be approved by BOEM or BSEE. Conditions 

of approval are based on BOEM’s technical and environmental evaluations of the proposed operations. 

Comments from Federal and State agencies (as applicable) are also considered in establishing conditions. 

Conditions may be applied to any OCS plan, permit, right-of-use of easement, or pipeline right-of-way 

grant.

Some BOEM-identified mitigating measures are implemented through cooperative agreements or 

coordination with the oil and gas industry and Federal and State agencies. These measures include the 

National Marine Fisheries Service’s (NMFS’s) Observer Program to protect marine mammals and sea 

turtles when OCS structures are removed using explosives, labeling of operational supplies to track 

sources of accidental debris loss, development of methods of pipeline landfall to eliminate impacts to 

barrier beaches, and semiannual beach cleanup events.

Refer to Chapters 1.5 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS for descriptions of postlease activities including G&G surveys; exploration and 

development plans; permits and applications; inspection and enforcement; pollution prevention, oil-spill 

response plans, and financial responsibility; air emissions; flaring and venting; hydrogen sulfide 

contingency plans; archaeological resources regulation; coastal zone management consistency review and 

appeals for plans; best available and safest technologies, including at production facilities; personnel 

training and education; structure removal and site clearance; marine protected species NTL’s; and the 

Rigs-to-Reefs program.

1.6. OTHER OCS OIL- AND GAS-RELATED ACTIVITIES

BOEM and BSEE have programs and activities that are OCS-related but not specific to the oil and 

gas leasing process or to the management of exploration, development, and production activities. These 

programs include environmental and technical studies, cooperative agreements with other Federal and 

State agencies for NEPA work, joint jurisdiction over cooperative efforts, inspection activities, OCS sand 

borrowing, and regulatory enforcement. BOEM also participates in industry research efforts and forums. 

Chapter 1.6 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS 

contain descriptions of the other OCS oil- and gas-related activities, including the Environmental Studies 

Program, Technology Assessment and Research Program, and interagency agreements.

CHAPTER 2 

ALTERNATIVES INCLUDING THE PROPOSED ACTIONS

Alternatives Including the Proposed Actions 2-3 

2. ALTERNATIVES INCLUDING THE PROPOSED ACTIONS

This Supplemental EIS addresses three proposed Federal actions: proposed oil and gas Lease Sales 

235, 241, and 247, in the CPA of the Gulf of Mexico OCS (Figure 1-1), as scheduled in the Five-Year 

Program (USDOI, BOEM, 2012a). The proposed actions (proposed lease sales) assume compliance with 

applicable regulations and lease stipulations in place at the time a ROD is signed for each proposed 

action.

2.1. SUPPLEMENTAL EIS NEPA ANALYSIS

Proposed CPA Lease Sales 235, 241, and 247 were analyzed in the 2012-2017 WPA/CPA Multisale 

EIS. This Supplemental EIS tiers from the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS, and it summarizes and hereby incorporates those documents by reference. Each of the

proposed lease sales is expected to be within the scenario ranges summarized in Chapter 3 of this 

Supplemental EIS and as discussed in Chapter 3 of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. 

Since proposed CPA Lease Sales 235, 241, and 247 and their projected activities are very similar, this 

Supplemental EIS encompasses the three proposed lease sales as authorized under 40 CFR § 1502.4, 

which allows related or similar proposals to be analyzed in one EIS. In addition, one Area ID was 

prepared for the proposed CPA lease sales. The Multisale EIS approach is intended to focus the 

NEPA/EIS process on the differences between the proposed lease sales and on new issues and 

information. It also lessens duplication and saves agency resources. At the completion of the NEPA 

process for this Supplemental EIS, a decision will be made on whether or how to hold proposed CPA 

Lease Sale 235. An additional NEPA review will be conducted in the year prior to proposed CPA Lease 

Sales 241 and 247 to address any relevant significant new information. This additional NEPA review 

could take the form of a determination of NEPA adequacy, an environmental assessment (EA), or if 

BOEM deems necessary, a supplemental EIS. Informal and formal consultation with other Federal 

agencies, the affected States, and the public will be carried out to assist in the determination of whether or 

not the information and analysis contained in this Supplemental EIS is still valid. Specifically, 

information requests will be issued soliciting input on proposed CPA Lease Sales 241 and 247.

This Supplemental EIS analyzes the potential impacts of a CPA proposed action on sensitive coastal 

environments, offshore marine resources, and socioeconomic resources both onshore and offshore, and it 

is the final NEPA review conducted for proposed CPA Lease Sale 235. It has been prepared to aid in the 

determination of whether or not new available information indicates that the proposed lease sales would 

result in new significant impacts not addressed in the 2012-2017 WPA/CPA Multisale EIS or 

WPA 233/CPA 231 Supplemental EIS. In preparation for this Supplemental EIS, BOEM utilized the best 

information available to determine if the baseline condition for resources had changed since publication 

of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. This best 

available information was derived from ongoing and past research and from review of peer-reviewed 

scientific reports and studies, as well as through review of sources open to BOEM’s subject-matter 

experts through Internet searches. Further discussion and analysis of newly identified information and 

best available information is contained in Chapters 3 and 4 and in Appendix B. This Supplemental EIS 

presents an impartial analysis of this new information. 

2.2. ALTERNATIVES, MITIGATING MEASURES, AND ISSUES

2.2.1. Alternatives

The alternatives to be considered for proposed CPA Lease Sales 235, 241, and 247 are detailed in 

Chapter 2.3 below. These suggested alternatives have been derived from both the historical comments 

submitted to BOEM and the EIS-specific scoping performed for this analysis.

Through our scoping efforts for this Supplemental EIS and previous EIS’s, numerous issues and 

topics were identified for consideration. During the scoping period for the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, a number of alternatives or deferral options 

were suggested and examined for inclusion in those EIS’s (Chapter 2.2.1.2 of the 2012-2017 WPA/CPA 
2-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

Multisale EIS and WPA 233/CPA 231 Supplemental EIS). Those alternative and deferral options were 

also reexamined during the preparation of this Supplemental EIS. These suggestions included additional 

deferrals, policy changes, and suggestions beyond the scope of this Supplemental EIS. BOEM has not 

identified any new significant information that changes its conclusions in the 2012-2017 WPA/CPA 

Multisale EIS or WPA 233/CPA 231 Supplemental EIS or that indicates that the proposed alternatives or 

deferral options are not appropriate for further in-depth analysis. The justifications for not carrying those 

suggestions through detailed analyses in this Supplemental EIS are the same as those used in the 2012-

2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

The analyses of environmental impacts from the proposed alternatives summarized in Chapter 

2.3.1.2 below and described in detail in Chapter 4.1.1 are based on the development scenario, which is a 

set of assumptions and estimates on the amounts, locations, and timing for OCS exploration, 

development, and production operations and facilities, both offshore and onshore. A detailed discussion 

of the development scenario and major related impact-producing factors is included in Chapter 3. 

2.2.1.1. Alternatives for Proposed Central Planning Area Lease Sales 235, 241, 

and 247

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

all unleased blocks within the proposed CPA 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; 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.

The DOI is conservative throughout the NEPA process and includes the total area within the CPA for 

environmental review even though the leasing of portions of the CPA (subareas or blocks) can be deferred 

during a Five-Year Program.

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

66.45 million ac. As of February 2014, approximately 43.5 million ac of the proposed CPA lease sale 

area are unleased. The estimated amount of resources projected to be developed as a result of a proposed 

CPA lease sale is 0.460-0.894 BBO and 1.939-3.903 Tcf of gas (Table 3-1). 

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

Topographic Features: This alternative would offer for lease all unleased blocks within the proposed 

CPA lease sale area, as described for the proposed action (Alternative A), but it would exclude from 

leasing any unleased blocks subject to the Topographic Features Stipulation. The estimated amount of 

resources projected to be developed is 0.460-0.894 BBO and 1.939-3.903 Tcf of gas (refer to

Chapter 2.3.2 for further details).

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

alternative is chosen, the opportunity for development of the estimated 0.460-0.894 BBO and 

1.939-3.903 Tcf of gas that could have resulted from a proposed CPA lease sale would be precluded 

during the current 2012-2017 Five-Year Program, but it could again be contemplated as part of a future 

Five-Year Program. Any potential environmental impacts arising out of a proposed CPA lease sale

would not occur, but activities associated with existing leases in the CPA would continue. This

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

Alternatives and Deferrals Considered but Not Analyzed in Detail

Chapter 2.2.1.2 of the 2012-2017 WPA/CPA Multisale EIS includes a detailed description of 

alternatives considered but not analyzed in this Supplemental EIS, including the following: exclude deep 

water and limit leasing to shallow waters; delay leasing until drilling safety is improved; do not allow 

drilling in areas with strong ocean currents such as the Loop Current; delay leasing until the state of the 

Gulf of Mexico environmental baseline is known; and identify and protect sensitive ecosystems. The 

justifications for not engaging in detailed analysis of these alternatives and deferrals in this Supplemental 
Alternatives Including the Proposed Actions 2-5 

EIS are the same as those used in the 2012-2017 WPA/CPA Multisale EIS, and BOEM has identified no 

new information that changes these conclusions.

2.2.2. Mitigating Measures

The NEPA process is intended to help public officials make decisions that are based on an 

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

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

reasonable mitigating measures and lease stipulations that could improve the action. 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.

2.2.2.1. Proposed Mitigating Measures Analyzed

The potential lease stipulations and mitigating measures included for analysis in this Supplemental 

EIS were developed as a result of numerous scoping efforts for the continuing OCS Program in the Gulf 

of Mexico. Ten lease stipulations (described in Chapter 2.4.1.3 of the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS) are proposed for CPA Lease Sales 235, 241, and 247—

the Topographic Features Stipulation; the Live Bottom (Pinnacle Trend) Stipulation; the Military Areas 

Stipulation; the Evacuation Stipulation; the Coordination Stipulation; the Blocks South of Baldwin 

County, Alabama, Stipulation; the Protected Species Stipulation; the Law of the Sea Convention Royalty 

Payment Stipulation; the Below Seabed Operations Stipulation; the Transboundary Stipulation. The Law 

of the Sea Convention Royalty Payment Stipulation is applicable to a proposed CPA lease sale even 

though it is not an environmental or military stipulation. 

These measures will be considered for adoption by the ASLM, under authority delegated by the 

Secretary of the Interior. The analysis of any stipulations for Alternative A does not ensure that the 

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

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

if comments indicate changes are necessary or if conditions change.

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

ROD for that lease sale. Mitigating measures in the form of lease stipulations are added to the lease terms 

and are therefore enforceable as part of the lease. In addition, each exploration and development plan, as 

well as any pipeline applications that result from a lease sale, will undergo a NEPA review and additional 

project-specific mitigations applied as conditions of plan approval. The BSEE has the authority to 

monitor and enforce these conditions and, under 30 CFR part 250 subpart N, may seek remedies and 

penalties from any operator that fails to comply with those conditions, stipulations, and mitigating 

measures.

2.2.2.2. Existing Mitigating Measures

Mitigating measures have been proposed, identified, evaluated, or developed through previous 

BOEM lease sale NEPA review and analysis. Many of these mitigating measures have been adopted and 

incorporated into regulations and/or guidelines governing OCS exploration, development, and production 

activities. All plans for OCS activities (e.g., exploration and development plans, pipeline applications, 
2-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

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 minimizing any adverse impact of 

routine operations on the environment). For example, certain measures ensure site clearance, and survey 

procedures are carried out to determine potential snags to commercial fishing gear and to avoid 

archaeological sites and biologically sensitive areas such as pinnacles, topographic features, and 

chemosynthetic communities. 

Some BOEM-identified mitigating measures are incorporated into OCS operations through 

cooperative agreements or efforts with industry and State and Federal agencies. These mitigating 

measures include mandating compliance with NMFS’s Observer Program to protect marine mammals and 

sea turtles during the use of explosives for structure removal, labeling operational supplies to track 

possible sources of debris or equipment loss, developing methods of pipeline landfall to eliminate impacts 

to beaches or wetlands, and requiring beach cleanup events.

Site-specific mitigating measures are also applied by BOEM during plan and permit reviews. BOEM 

realized that many of these site-specific mitigations were recurring and developed a list of “standard” 

mitigations. There are currently over 120 standard mitigations. The wording of a standard mitigation is 

developed by BOEM in advance and may be applied whenever conditions warrant. Standard mitigation 

text is revised as often as is necessary (e.g., to reflect changes in regulatory citations, agency/personnel 

contact numbers, and internal policy). Site-specific mitigation “categories” include the following: air 

quality; archaeological resources; artificial reef material; chemosynthetic communities; Flower Garden 

Banks; topographic features; hard bottom/pinnacles, 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 apply nonrecurring mitigating 

measures that are developed on a case-by-case basis.

BOEM is continually revising applicable mitigations to allow the Gulf of Mexico OCS Region to 

more easily and routinely track mitigation compliance and effectiveness. A primary focus of this effort is 

requiring post-approval submittal of information within a specified timeframe or after a triggering event 

(e.g., end of operations reports for plans, construction reports for pipelines, and removal reports for 

structure removals).

2.2.3. Issues

Issues are defined in CEQ Guidance as the principal “effects” that an EIS should evaluate in-depth. 

Selection of environmental and socioeconomic issues to be analyzed was based on the following criteria:

• the issue is identified in CEQ regulations as subject to evaluation;

• the relevant resource/activity was identified through agency expertise, through the 

scoping process, or from comments on past EIS’s;

• 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

• the information that indicates a need to evaluate the potential impacts to a 

resource/activity has become available.

2.2.3.1. Issues to be Analyzed

Chapter 2.2.3.1 of the 2012-2017 WPA/CPA Multisale EIS addresses the issues related to potential 

impact-producing factors and the environmental and socioeconomic resources and activities that could be 

affected by OCS exploration, development, production, and transportation activities (i.e., accidental 
Alternatives Including the Proposed Actions 2-7 

events, drilling fluids and cuttings, visual and aesthetic interference, air emissions, water quality

degradation and other wastes, structure and pipeline emplacement, platform removals, OCS-related 

support services, activities, and infrastructure, socio-cultural and socioeconomic, and OCS oil and gas 

infrastructure). Chapter 4.2 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS, and Chapter 4.1 of this Supplemental EIS describe the resources and activities that 

could be affected by the impact-producing factors listed above and include the following resource topics:

— Air Quality

— Alabama, Choctawhatchee, St. Andrew, 

and Perdido Key Beach Mice

— Archaeological Resources (Historic and 

Prehistoric)

— Coastal Barrier Beaches and Associated 

Dunes

— Coastal and Marine Birds

— Commercial Fisheries

— Deepwater Benthic Communities 

(Chemosynthetic and 

Nonchemosynthetic)

— Diamondback Terrapins

— Fish Resources and Essential Fish 

Habitat

— Gulf Sturgeon

— Human Resources and Land Use

(Land Use and Coastal 

Infrastructure, Demographics, 

Economic Factors, and 

Environmental Justice) 

— Live Bottoms (Pinnacle Trend and 

Low Relief) 

— Marine Mammals

— Recreational Fishing

— Recreational Resources

— Sargassum Communities

— Sea Turtles

— Seagrass Communities

— Soft Bottom Benthic Communities

— Topographic Features

— Water Quality (Coastal and Offshore)

— Wetlands

2.2.3.2. Issues Considered but Not Analyzed

As previously noted, the CEQ regulations for implementing NEPA instruct agencies to adopt an early 

process (termed “scoping”) for determining the scope of issues to be addressed and for identifying 

significant issues related to a proposed action. As part of this scoping process, agencies shall identify and 

eliminate from detailed study the issues that are not significant to a CPA proposed action or have been 

covered by prior environmental review. No additional issues were identified during scoping that are not 

addressed in this Supplemental EIS. Comments received during scoping are summarized in Chapter 5.3. 

2.3. PROPOSED CENTRAL PLANNING AREA LEASE SALES 235, 241, AND 247

2.3.1. Alternative A—The Proposed Action (Preferred Alternative)

2.3.1.1. Description

Alternative A would offer for lease all unleased blocks within the proposed CPA lease sale area for oil 

and gas operations (Figure 2-1), with the following exception:

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

2006; 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.

The DOI is conservative throughout the NEPA process and includes the total area within the CPA for 

environmental review even though the leasing of portions of the CPA (subareas or blocks) can be deferred 

during a Five-Year Program.

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

66.45 million ac. As of February 2014, approximately 43.5 million ac of the proposed CPA lease sale 

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

proposed CPA lease sale is 0.460-0.894 BBO and 1.939-3.903 Tcf of gas (Table 3-1). 
2-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

The analyses of impacts summarized below and described in detail in Chapter 4.1.1 are based on the 

development scenario, which is a set of assumptions and estimates on the amounts, locations, and timing 

for OCS 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. 

Alternative A has been identified as BOEM’s preferred alternative; however, this does not mean that 

another alternative may not be selected in the Record of Decision.

2.3.1.2. Summary of Impacts

A search by BOEM’s subject-matter experts was conducted for each resource to consider new 

information made available since publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS and to consider new information on the Deepwater Horizon explosion, 

oil spill, and response. It must also be emphasized that, in arriving at the overall conclusions for certain 

environmental resources (e.g., coastal and marine birds, fisheries, and wetlands), the conclusions are not 

based on impacts to individuals, small groups of animals, or small areas of habitat, but on impacts to the 

resources/populations as a whole. Any new information discovered was analyzed by BOEM’s subjectmatter experts to determine if the impact conclusions presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS were altered as a result of the new information.

For the following resources, BOEM’s subject-matter experts determined through literature searches 

and communications with other agencies and academia that there was no new information made available 

since publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS 

that was relevant to potential impacts from a CPA proposed action. Therefore, the impact conclusions for 

these resources remain the same as those that were presented in the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS. These impact conclusions are presented in Chapter 4.1.1 of 

this Supplemental EIS. For ease of review, the individual chapter numbers for each resource are provided 

in the following list.

• Air Quality (Chapter 4.1.1.1) 

• Water Quality (Coastal and Offshore Waters) (Chapters 4.1.1.2.1 and 4.1.1.2.2, 

respectively)

• Coastal Barrier Beaches and Associated Dunes (Chapter 4.1.1.3) 

• Seagrass Communities (Chapter 4.1.1.5) 

• Live Bottoms (Pinnacle Trend and Low Relief) (Chapter 4.1.1.6) 

• Topographic Features (Chapter 4.1.1.7) 

• Sargassum Communities (Chapter 4.1.1.8) 

• Chemosynthetic Deepwater Benthic Communities (Chapter 4.1.1.9) 

• Nonchemosynthetic Deepwater Benthic Communities (Chapter 4.1.1.10) 

• Soft Bottom Benthic Communities (Chapter 4.1.1.11) 

• Gulf Sturgeon (Chapter 4.1.1.17) 

• Fish Resources and Essential Fish Habitat (Chapter 4.1.1.18) 

• Species Considered due to U.S. Fish and Wildlife Service Concerns (Chapter 

4.1.1.24) 

For the following resources, BOEM’s subject-matter experts determined through literature searches 

and communications with other agencies and academia that there was new information made available 

since publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS

that was relevant to potential impacts from a CPA proposed action. BOEM’s subject-matter experts have 

reexamined the analyses for these resources based on new information made available; however, none of 
Alternatives Including the Proposed Actions 2-9 

the new information was deemed significant in that it did not alter of the impact conclusions presented in

the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. These impact 

conclusions are presented in Chapter 4.1.1. For ease of review, the individual chapter numbers for each 

resource are provided in the following list.

• Wetlands (Chapter 4.1.1.4) 

• Marine Mammals (Chapter 4.1.1.12) 

• Sea Turtles (Chapter 4.1.1.13) 

• Diamondback Terrapins (Chapter 4.1.1.14) 

• Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice (Chapter 

4.1.1.15) 

• Coastal and Marine Birds (Chapter 4.1.1.16) 

• Commercial Fisheries (Chapter 4.1.1.19) 

• Recreational Fishing (Chapter 4.1.1.20) 

• Recreational Resources (Chapter 4.1.1.21) 

• Archaeological Resources (Historic and Prehistoric) (Chapters 4.1.1.22.1 and 

4.1.1.22.2, respectively) 

• Human Resources and Land Use (Land Use and Coastal Infrastructure, 

Demographics, Economic Factors, and Environmental Justice) (Chapters 4.1.1.23.1, 

4.1.1.23.2, 4.1.1.23.3, and 4.1.1.23.4, respectively) 

Ultimately, no new significant information was discovered that would alter the impact conclusions for 

any of the resources analyzed in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analyses and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS remain valid and, as such, apply for proposed CPA Lease 

Sales 235, 241, and 247. 

In accordance with CEQ recommendations to provide decisionmakers with a robust environmental 

analysis, Appendix B (“Catastrophic Spill Event Analysis”) provides an analysis of the potential impacts 

of a low-probability, catastrophic oil spill, which is not reasonably expected and not part of a CPA 

proposed action, to the environmental and cultural resources and the socioeconomic conditions analyzed

in Chapter 4.1.1

2.3.1.3. Mitigating Measures

2.3.1.3.1. Topographic Features Stipulation

The topographic features located in the CPA provide habitat for coral-reef-community organisms 

(Chapter 4.1.1.7). These communities could be severely and adversely impacted by oil and gas activities 

resulting from a CPA proposed action if such activities took place on or near these communities without 

the Topographic Features Stipulation and if such activities were not mitigated. The DOI has recognized 

this problem for some years and, since 1973, has made lease stipulations a part of leases on or near these 

biotic communities so that impacts from nearby oil and gas activities were mitigated to the greatest extent 

possible. This stipulation would not prevent the recovery of oil and gas resources but would serve to 

protect valuable and sensitive biological resources.

The Topographic Features Stipulation was formulated based on consultation with various Federal 

agencies and comments solicited from the States, industry, environmental organizations, and academic 

representatives. This stipulation has been updated over time, using years of scientific information 

collected since the stipulation was first proposed. This information includes numerous Agency-funded 

studies of topographic features in the GOM; numerous stipulation-imposed, industry-funded monitoring 

reports; and the National Research Council (NRC) report entitled Drilling Discharges in the Marine 
2-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

Environment (1983). This stipulation protects these biotic communities from routine oil and gas activities 

resulting from a CPA proposed action, while allowing the development of nearby oil and gas resources. 

This stipulation would not prevent adverse effects of an accident such as a large blowout on a nearby oil 

or gas operation from impacting these biotic communities. The location of the blocks affected by the 

Topographic Features Stipulation is shown on Figure 2-1. A more detailed discussion and definition of 

this stipulation and its effectiveness are found in Chapter 2.4.1.3.1 of the 2012-2017 WPA/CPA Multisale 

EIS.

2.3.1.3.2. Live Bottom (Pinnacle Trend) Stipulation

The Live Bottom (Pinnacle Trend) Stipulation covers the pinnacle trend area of the proposed CPA 

lease sale area. A small portion of the northeastern proposed CPA lease sale area is characterized by a 

pinnacle trend, which is classified as a live bottom under the stipulation. The pinnacles are a series of 

topographic irregularities with variable biotal coverage, which provide structural habitat for a variety of 

pelagic fish. The pinnacles in the region could be impacted from physical damage of unrestricted oil and 

gas activities, as noted in Chapter 4.1.1.6. The Live Bottom (Pinnacle Trend) Stipulation is intended to 

protect the pinnacle trend and the associated hard bottom communities from damage and, at the same 

time, provide for recovery of potential oil and gas resources. The location of the pinnacle trend areas of 

the proposed CPA lease sale area is shown on Figure 2-1. A more detailed discussion and definition of 

this stipulation and its effectiveness are found in Chapter 2.4.1.3.2 of the 2012-2017 WPA/CPA Multisale 

EIS.

2.3.1.3.3. Military Areas Stipulation

The Military Areas Stipulation has been applied to all blocks leased in military areas since 1977 and 

reduces potential impacts, particularly in regards to safety. However, this stipulation does not reduce or 

eliminate the actual physical presence of oil and gas operations in areas where military operations are 

conducted. The stipulation contains a “hold harmless” clause (holding the U.S. Government harmless in 

case of an accident involving military operations) and requires lessees to coordinate their activities with 

appropriate local military contacts. Figure 2-2 shows the military warning areas in the Gulf of Mexico. 

A more detailed discussion and definition of this stipulation and its effectiveness are found in Chapter 

2.3.1.3.2 of the 2012-2017 WPA/CPA Multisale EIS.

2.3.1.3.4. Evacuation Stipulation

The Evacuation Stipulation would be a part of any lease in the easternmost portion of the proposed 

CPA lease sale area resulting from a CPA proposed action, i.e., Lease Sales 235, 241, and 247. This 

stipulation would provide for evacuation of personnel and shut-in of operations during any events 

conducted by the military that could pose a danger to ongoing oil and gas operations. It is expected that 

the invocation of these evacuation requirements will be extremely rare.

It is expected that these measures will serve to eliminate dangerous conflicts between oil and gas 

operations and military operations. Continued close coordination between BSEE and the military may 

result in improvements in the wording and implementation of these stipulations.

An evacuation stipulation has been applied to all blocks leased in this area since 2001. A more 

detailed discussion and definition of this stipulation and its effectiveness are found in Chapter 2.4.1.3.4 of 

the 2012-2017 WPA/CPA Multisale EIS.

2.3.1.3.5. Coordination Stipulation

The Coordination Stipulation would be a part of any lease in the easternmost portion of the proposed 

CPA lease sale area resulting from a CPA proposed action, i.e., Lease Sales 235, 241, and 247. This 

stipulation would provide for review of pending oil and gas operations by military authorities and could 

result in delaying oil and gas operations if military activities have been scheduled in the area that may put 

the oil and gas operations and personnel at risk.

A coordination stipulation has been applied to all blocks leased in this area since 2001. A more 

detailed discussion and definition of this stipulation and its effectiveness are found in Chapter 2.4.1.3.5 of 

the 2012-2017 WPA/CPA Multisale EIS.
Alternatives Including the Proposed Actions 2-11

2.3.1.3.6. Blocks South of Baldwin County, Alabama, Stipulation

The Blocks South of Baldwin County, Alabama, Stipulation will 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. A more detailed discussion and definition of this 

stipulation and its effectiveness are found in Chapter 2.4.1.3.6 of the 2012-2017 WPA/CPA Multisale 

EIS.

2.3.1.3.7. Protected Species Stipulation

The Protected Species Stipulation has been applied to all blocks leased in the GOM since December 

2001. This stipulation was developed in consultation with the Department of Commerce, National 

Oceanic and Atmospheric Administration, NMFS and the Department of the Interior, FWS in accordance 

with section 7 of the Endangered Species Act, and it is designed to minimize or avoid potential adverse 

impacts to federally protected species. A more detailed discussion and definition of this stipulation and 

its effectiveness are found in Chapter 2.3.1.3.3 of the 2012-2017 WPA/CPA Multisale EIS.

2.3.1.3.8. Law of the Sea Convention Royalty Payment Stipulation

The Law of the Sea Convention Royalty Payment Stipulation applies to blocks or portions of blocks 

beyond the U.S. Exclusive Economic Zone (generally greater than 200 nmi [230 mi; 370 km] from the 

U.S. coastline). Leases on these blocks may be subject to special royalty payments under the provisions 

of the 1982 Law of the Sea Convention (consistent with Article 82), if the U.S. becomes a party to the 

Convention prior to or during the life of the lease. A more detailed discussion and definition of this 

stipulation and its effectiveness are found in Chapter 2.3.1.3.4 of the 2012-2017 WPA/CPA Multisale 

EIS.

2.3.1.3.9. Below Seabed Operations Stipulation

The Below Seabed Operations Stipulation language is intended to be lease sale-specific language and 

would incorporate maps of the blocks that may be affected. This stipulation can be found in Chapter 

2.4.1.3.9 of the 2012-2017 WPA/CPA Multisale EIS.

2.3.1.3.10. Transboundary Stipulation

The “Agreement Between the United States of America and the United Mexican States Concerning 

Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico,” once it enters into force, will make it 

possible for U.S. lessees to enter into voluntary agreements with a licensee of the United Mexican States 

to develop transboundary reservoirs. The stipulation applies 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 Transboundary 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. For more information, refer to the Transboundary Agreement available at 

http://www.boem.gov/BOEM-Newsroom/Library/Publications/Agreement-between-the-United-Statesand-Mexico-Concerning-Transboundary-Hydrocarbon-Reservoirs-in-the-Gulf-of-Mexico.aspx. 

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

the Biologically Sensitive Topographic Features

2.3.2.1. Description

Alternative B differs from Alternative A by not offering the blocks that are potentially subject to the 

proposed Topographic Features Stipulation (Chapter 2.4.1.3.1 of the 2012-2017 WPA/CPA Multisale EIS 
2-12 Central Planning Area Lease Sales 235, 241, and 247 EIS

and Figure 2-1 of this Supplemental EIS). All other assumptions (including the 9 other potential 

mitigating measures and the 1 stipulation) and estimates are the same as for Alternative A. The estimated 

amount of resources projected to be developed is 0.460-0.894 BBO and 1.939-3.903 Tcf of gas.

2.3.2.2. Summary of Impacts

The analyses of impacts summarized in Chapter 2.3.1.2 and described in detail in Chapter 4.1.1 are 

based on the development scenario, which is a set of assumptions and estimates on the amounts, 

locations, and timing for OCS exploration, development, and production operations and facilities, both 

offshore and onshore. A detailed discussion of the development scenario and major related impactproducing factors is included in Chapter 3. 

The difference between the potential impacts described for Alternative A and those under 

Alternative B is that under Alternative B no oil and gas activity would take place in the blocks subject to 

the Topographic Features Stipulation (Figure 2-1). The number of blocks that would not be offered 

under Alternative B represents only a small percentage of the total number of blocks to be offered under 

Alternative A; therefore, it is assumed that the levels of activity for Alternative B would be similar to 

those projected for a CPA proposed action. As a result, the impacts expected to result from Alternative B 

would be very similar to those described under a CPA proposed action (Chapter 4.1.1). Regional impact 

levels for all resources, except for the topographic features, would be similar to those described under a 

CPA proposed action. This alternative, if adopted, would prevent any oil and gas activity whatsoever in 

the affected blocks; thus, it would eliminate any potential direct impacts to the biota of those blocks from 

oil and gas activities, which otherwise would be conducted within the blocks.

2.3.3. Alternative C—No Action

2.3.3.1. Description

Alternative C is the cancellation of a proposed CPA lease sale. If this alternative is chosen, the 

opportunity for development of the estimated 0.460-0.894 BBO and 1.939-3.903 Tcf of gas that could 

have resulted from a proposed CPA lease sale would be precluded or postponed to a future CPA lease 

sale. Any potential environmental impacts arising out of a proposed CPA lease sale would not occur, but 

activities associated with existing leases in the CPA would continue. The No Action alternative, 

therefore, encompasses the same potential impacts as a decision to delay the leasing of unleased blocks in 

the CPA to a later scheduled lease sale under the Five-Year Program, when another decision on whether 

to hold that future lease sale would be made. Because delay of a proposed CPA lease sale would yield 

essentially the same results as the No Action alternative (i.e., most impacts related to Alternative A would 

not occur), delay of a proposed lease sale was not considered as a separate alternative under this 

Supplemental EIS.

2.3.3.2. Summary of Impacts

Canceling a proposed CPA lease sale would eliminate the effects described for Alternative A 

(Chapter 4.1.3). The incremental contribution of a proposed lease sale to the cumulative effects would 

also be foregone, but the effects from other activities, including other previous OCS lease sales, would 

remain. Moreover, if a proposed CPA lease sale was canceled, the resulting development of oil and gas 

could be reevaluated under a future proposed lease sale. Therefore, the overall level of OCS activity in 

the CPA would only be reduced by a small percentage, if any, and the cancellation of a proposed CPA 

lease sale would not significantly change the environmental impacts of overall OCS activity in the short 

term at least. However, the cancellation of a proposed CPA lease sale could result in direct economic 

impacts to the individual companies. Revenues collected by the Federal Government (and thus revenue 

disbursements to the States) also would be adversely affected.

If a proposed CPA lease sale was canceled, then other sources of energy could potentially be 

substituted for the lost production. Principal substitutes would be additional imports, conservation, 

additional domestic production, and switching to other fuels. These alternatives, except conservation, 

have significant negative environmental impacts of their own. For example, the tankering of fuels from 

alternate sources over longer distances may have significant potential negative impacts, including the 

increased risk of spills in the Gulf of Mexico.
CHAPTER 3 

IMPACT-PRODUCING FACTORS AND SCENARIO

Impact-Producing Factors and Scenario 3-3 

3. IMPACT-PRODUCING FACTORS AND SCENARIO

3.1. IMPACT-PRODUCING FACTORS AND SCENARIO—ROUTINE OPERATIONS

3.1.1. Offshore Impact-Producing Factors and Scenario

Chapter 3.1.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 3.1.1 of the WPA 233/

CPA 231 Supplemental EIS describe in detail the offshore infrastructure and activities (impact-producing 

factors) associated with a CPA proposed action (i.e., a typical lease sale that would result from a proposed 

action) within the CPA that could potentially affect the biological, physical, and socioeconomic resources 

of the Gulf of Mexico. In addition, Chapter 3.1.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 

3.1.1 of the Gulf of Mexico OCS Oil and Gas Lease Sales: 2014 and 2016; Eastern Planning Area Lease 

Sales 225 and 226; Final Environmental Impact Statement (EPA 225/226 EIS) (USDOI, BOEM, 2013b) 

also describe the OCS Program’s cumulative activity scenario resulting from past and future lease sales in 

the WPA, CPA, and EPA that could potentially affect the biological, physical, and socioeconomic 

resources of the GOM within the CPA. Note that offshore and onshore impact-producing factors and 

scenarios associated with a WPA or an EPA proposed action (i.e., a typical lease sale that would result 

from a proposed action within the WPA or EPA) as well as OCS Program activity resulting from past and 

future lease sales in the WPA or EPA are disclosed in the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS (Gulf of Mexico OCS Oil 

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

Environmental Impact Statement), and EPA 225/226 EIS. 

Offshore is defined, for the purposes of this Supplemental EIS, as the OCS portion of the GOM that 

begins 3 marine leagues (9 nmi; 10.36 mi; 16.67 km) offshore Texas and Florida and 3 nmi (3.5 mi; 

5.6 km) offshore Louisiana, Mississippi, and Alabama. The OCS extends seaward to the limits of the 

United States’ jurisdiction over the continental shelf in water depths up to approximately 3,346 m 

(10,978 ft), which comprises the Exclusive Economic Zone (Figure 1-1). Coastal infrastructure and 

activities associated with a CPA proposed action are described in Chapter 3.1.2 of this Supplemental EIS

and in Chapter 3.1.2 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS. 

BOEM projects that the overwhelming majority of the oil and natural gas fields discovered as a result 

of a CPA proposed action will reach the end of their economic life within a time span of 40 years 

following a lease sale. Therefore, activity levels are projected to 40 years for this Supplemental EIS. 

Although unusual cases exist where activity on a lease may continue beyond 40 years, BOEM’s forecasts 

indicate that most significant activities associated with exploration, development, production, and 

abandonment of leases in the GOM occur well within the 40-year analysis period. For the cumulative 

case analysis, total OCS Program exploration and development activities are also forecast over a 40-year 

period. For modeling purposes and quantitative OCS Program activity analyses, a 40-year analysis period 

is also used. Exploration and development activity forecasts become increasingly more uncertain as the 

length of time of the forecast increases and the number of influencing factors increases.

BOEM uses a series of spreadsheet-based data analysis tools to develop the forecasts of oil and gas 

exploration, discovery, development, and production activity for a proposed action and OCS Program 

scenarios presented in this Supplemental EIS. BOEM’s analyses incorporate all relevant historical 

activity and infrastructure data, and BOEM’s resulting forecasts are analyzed and compared with actual 

historical data to ensure that historical precedent and recent trends are reflected in each activity forecast.

BOEM is confident that its analysis methodology, with adjustments and refinements based on recent 

activity levels, adequately projects Gulf of Mexico OCS activities in both the short term and the long term 

for the EIS analyses.

The CPA proposed actions and the Gulfwide OCS Program scenarios are based on the following 

factors:

• resource estimates developed by BOEM;

• recent trends in the amount and location of leasing, exploration, and development 

activity;
3-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

• estimates of undiscovered, unleased, economically recoverable oil and gas resources 

in each water-depth category and each planning area;

• existing offshore and onshore oil and/or gas infrastructure; 

• published data and information;

• industry information; and

• oil and gas technologies, and the economic considerations and environmental 

constraints of these technologies.

Proposed CPA Lease Sales 235, 241, and 247 each represent 3-4 percent of the OCS Program 

activities expected in the CPA from 2012 through 2051 based on barrels of oil equivalent (BOE) resource 

estimates and 2.5-3.5 percent of the total OCS Program (WPA, CPA, and EPA) from 2012 through 2051. 

Specific projections for activities associated with a CPA proposed action are discussed in the 

following scenario sections. The potential impacts of the activities associated with a proposed “typical” 

CPA lease sale are considered in the environmental analysis sections (Chapter 4.1.1 of this Supplemental 

EIS and Chapter 4.2.1 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS). 

The OCS Program scenario includes all activities that are projected to occur from past, proposed, and 

future lease sales during the analysis period. This includes projected activity from lease sales that have 

been held but for which exploration or development has either not yet begun or is continuing. Activities 

that take place beyond the analysis timeframe as a result of future lease sales are not included in this 

analysis. The impacts of activities associated with the OCS Program on biological, physical, and 

socioeconomic resources are analyzed in the cumulative environmental analysis sections (Chapter 4.1.1

of this Supplemental EIS and Chapter 4.2.1 of the 2012-2017 WPA/CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS).

3.1.1.1. Resource Estimates and Timetables

The CPA proposed actions and cumulative cases have not changed since last analyzed for the 2012-

2017 WPA/CPA Multisale EIS. BOEM has not identified any new information or change in 

circumstances since publication of the 2012-2017 WPA/CPA Multisale EIS or WPA 233/CPA 231 

Supplemental EIS that would change the estimates and timetables.

3.1.1.1.1. Proposed Action

The proposed action scenario is used to assess the potential impacts of a proposed “typical” lease sale. 

The resource estimates for a proposed action are based on two factors: (1) the conditional estimates of 

undiscovered, unleased, conventionally recoverable oil and gas resources in the proposed lease sale area; 

and (2) estimates of the portion or percentage of these resources assumed to be leased, discovered, 

developed, and produced as a result of a proposed action. Due to the inherent uncertainties associated 

with an assessment of undiscovered resources, probabilistic techniques were employed and the results 

were reported as a range of values corresponding to different probabilities of occurrence. The estimates 

of the portion of the resources assumed to be leased, discovered, developed, and produced as a result of a 

proposed action are based upon logical sequences of events that incorporate past experience, current 

conditions, and foreseeable development strategies. Historical databases and information derived from oil 

and gas exploration and development activities are available to BOEM and were used extensively. The 

undiscovered, unleased, conventionally recoverable resource estimates for a proposed action are 

expressed as ranges, from low to high. This range provides a reasonable expectation of oil and gas 

production anticipated from a typical lease sale held as a result of a proposed action based on an actual 

range of historic observations.

Table 3-1 presents the projected oil and gas production for a CPA proposed action and for the OCS 

Program. Table 3-2 provides a summary of the major scenario elements of a CPA proposed action, a 

“typical” lease sale, and related impact-producing factors. To analyze impact-producing factors for a 

CPA proposed action and the OCS Program, the proposed CPA lease sale area was divided into offshore 

subareas based upon ranges in water depth. Figure 3-1 depicts the location of the offshore subareas. The 
Impact-Producing Factors and Scenario 3-5 

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.

Proposed Action Scenario (CPA Typical Lease Sale): The estimated amounts of resources projected 

to be leased, discovered, developed, and produced as a result of a typical proposed CPA lease sale are 

0.460-0.894 BBO and 1.939-3.903 Tcf of gas.

The number of exploration and delineation wells, production platforms, and development wells 

projected to develop and produce the estimated resources for a CPA proposed action is given in Table 3-

2. The table shows the distribution of these factors by offshore subareas in the proposed lease sale area. 

Table 3-2 includes estimates of the major impact-producing factors related to the projected levels of 

exploration, development, and production activity.

Exploratory drilling activity generally takes place over an 8-year period, beginning within 1 year after 

a lease sale. Development activity generally takes place over a 39-year period, beginning with the 

installation of the first production platform and ending with the drilling of the last development wells. 

Production of oil and gas begins by the third year after a lease sale and would likely conclude by year 40; 

however, in rare cases, production could continue beyond year 40. 

3.1.1.1.2. OCS Program

OCS Program Cumulative Scenario (WPA, CPA, and EPA): Projected reserve/resource production 

for the OCS Program is 18.335-25.64 BBO and 75.886-111.627 Tcf of gas and represents anticipated 

production from lands currently under lease plus anticipated production from future lease sales over the 

40-year analysis period. The OCS Program cumulative scenario includes WPA, CPA, and EPA 

production estimates. Table 3-3 presents all anticipated production from lands currently under lease in 

the WPA, CPA, and EPA plus all anticipated production from future total OCS Program (WPA, CPA, 

and EPA) lease sales over the 40-year analysis period.

WPA Cumulative Scenario: Projected reserve/resource production for the OCS Program in the WPA 

(2.510-3.696 BBO and 12.539-18.434 Tcf of gas) represents anticipated production from lands currently 

under lease in the WPA plus anticipated production from future WPA lease sales over the 40-year 

analysis period. Projected production under the cumulative scenario represents approximately 14 percent 

of the oil and 17 percent of the gas of the total Gulfwide OCS Program. Table 3-4 of the WPA 

238/246/248 Supplemental EIS presents all anticipated production from lands currently under lease in the 

WPA plus all anticipated production from future WPA lease sales over the 40-year analysis period. The 

impact-producing factors, affected environment, and environmental consequences related to WPA 

proposed lease sales are disclosed in the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 

Supplemental EIS, and WPA 238/246/248 Supplemental EIS.

CPA Cumulative Scenario: Projected reserve/resource production for the OCS Program in the CPA 

(15.825-21.733 BBO and 63.347-92.691 Tcf of gas) represents anticipated production from lands 

currently under lease in the CPA plus anticipated production from future CPA lease sales over the 40-year 

analysis period. Projected production under the cumulative scenario represents approximately 

85-86 percent of the oil and 83 percent of the gas of the total Gulfwide OCS Program. Table 3-4 presents 

all anticipated production from lands currently under lease in the CPA plus all anticipated production 

from future CPA lease sales over the 40-year analysis period. The impact-producing factors, affected 

environment, and environmental consequences related to CPA proposed lease sales are disclosed in this 

Supplemental EIS, the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

EPA Cumulative Scenario: Projected reserve/resource production for the OCS Program in the EPA 

(0-0.211 BBO and 0-0.502 Tcf of gas) represents all anticipated production from lands currently under 

lease in the EPA plus all anticipated production from future EPA lease sales over the 40-year analysis 

period. Projected production represents approximately 1 percent of the oil and <1 percent of the gas of 

the total Gulfwide OCS Program. Table 3-3 in the EPA 225/226 EIS presents all anticipated production 

from lands currently under lease in the EPA plus all anticipated production from future EPA lease sales 

over the 40-year analysis period. The impact-producing factors, affected environment, and environmental 

consequences related to EPA proposed lease sales are disclosed in the EPA 225/226 EIS.
3-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

3.1.1.2. Exploration and Delineation

3.1.1.2.1. Seismic Surveying Operations

Chapter 3.1.1.2.1 of the 2012-2017 WPA/CPA Multisale EIS describes in detail seismic survey 

operations including ocean-bottom surveys.

Prelease surveys are comprised of seismic work performed on or off leased areas, focused most 

commonly (but not always) on deeper targets and collectively authorized under BOEM’s geological and 

geophysical permitting process. Postlease, high-resolution seismic surveys collect data on surficial or 

near-surface geology used to identify potential shallow geologic hazards for engineering and site planning 

for bottom-founded structures. Noise associated with OCS oil and gas development results from seismic 

surveys, the operation of fixed structures such as offshore platforms and drilling rigs, and helicopter and 

service-vessel traffic. These noise sources are discussed in Chapter 3.1.1.6 of this Supplemental EIS and 

in Chapter 3.1.1.6 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS). 

CPA Proposed Action Scenario (Typical Lease Sale): Because of the cyclic nature in the acquisition 

of seismic surveys, a prelease seismic survey would be attributable to lease sales held up to 7-9 years after 

the survey. Based on an amalgam of historical trends in G&G permitting and industry input, BOEM 

projects that proposed lease sales within the EPA, WPA, and CPA would result in 29,197 OCS blocks 

surveyed by 2D and 3D deep seismic operations for the years 2012-2017. Broken down per planning 

area, this yields approximately 21,314 blocks in the CPA, approximately 7,300 blocks in the WPA, and 

approximately 583 blocks in the EPA. It should be noted that the number of blocks could include 

multiple surveys on a single block that would then be counted each time as a unique block survey. For 

postlease seismic surveys, information obtained from high-resolution seismic contractors operating in the 

GOM project the proposed actions would result in about 50 vertical seismic profiling (VSP) operations 

and 629 high-resolution surveys covering approximately 226,400 line miles (364,420 km) of near-surface 

and shallow penetration seismic during the life of the proposed actions. The impact-producing factors, 

affected environment, and environmental consequences related to CPA proposed lease sales are disclosed 

and addressed in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

OCS Program Cumulative Scenario: Seismic surveys are projected to follow the same trend as 

exploration activities, which peaked in 2008-2010, will steadily decline until 2027, and will remain 

relatively steady throughout the second half of the 40-year analysis period. It is important to note that the 

cycling of G&G data acquisition is not driven by the 40-year life cycle of productive leasing, but instead 

will trend to respond to new production or potential new production driven by new technology. 

Consequently, some areas will be resurveyed in 2-year cycles, while other areas, considered 

nonproductive, may not be surveyed for 20 years or more.

Assuming that acoustic-sourced seismic will remain the dominant exploration tool used by industry in 

the future and that a number of surveyed blocks will be resurveying several more times, BOEM makes the 

following projections. During the first 5 years (2012-2017) of the analysis period (2012-2051), BOEM 

projects the following annual activities: 50 VSP operations; 226,400 lines miles (364,420 km) surveyed 

by high-resolution seismic; and 29,197 blocks surveyed by deep seismic, including areas that will be 

resurveyed. Expanding this analysis to the first 20 years (2012-2032), the annual projections would be 

60 VSP operations, 400,000 mi (740,800 km) of high-resolution seismic, and 33,000 blocks of 2D/3D 

deep seismic (10% in EPA, 60% in CPA, and 30% in WPA). During the second half of the 40-year 

analysis period, the annual projection would be approximately 40 VSP operations, 240,000 mi 

(444,480 km) surveyed by high-resolution seismic, and 15,000-20,000 blocks surveyed by deep seismic

(50% in the CPA, 30% in the WPA, and 20% in the EPA).

3.1.1.2.2. Exploration and Delineation Plans and Drilling

Chapter 3.1.1.2.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail exploration and 

delineation plans and drilling.

Oil and gas operators use drilling terms that represent stages in the discovery and exploitation of 

hydrocarbon resources. An exploration well generally refers to the first well drilled on a prospective 

geologic structure to confirm that a resource exists. If a resource is discovered in quantities appearing to 

be economically viable and in circumstances when reservoirs are large, one or more follow-up delineation 

wells help define the amount of resource or the extent of the reservoir. Following a discovery, an 
Impact-Producing Factors and Scenario 3-7 

operator will often temporarily plug and abandon a discovery to allow time to generate a development 

scenario and to build or procure equipment.

In the GOM, exploration and delineation wells are typically drilled with mobile offshore drilling units 

(MODU’s); e.g., jack-up rigs, semisubmersible rigs, submersible rigs, platform rigs, or drillships. 

Non-MODU, such as inland barges, are also used. The type of rig chosen to drill a prospect depends 

primarily on water depth. Because the water-depth ranges for each type of drilling rig overlap to a 

degree, other factors such as rig availability and daily operation rates play a large role when an operator 

decides upon the type of rig to contract. The depth ranges for exploration rigs used in this analysis for 

Gulf of Mexico MODU’s are indicated below.

MODU or Drilling Rig Type Water-Depth Range

Jack-up, submersible, and inland barges ≤100 m (328 ft)

Semisubmersible and platform rig 100-3,000 m (328-9,843 ft)

Drillship ≥600 m (1,969 ft)

Historically, drilling rig availability has been a limiting factor for activity in the GOM and is assumed 

to be a limiting factor for activity projected as a result of a proposed lease sale. Drilling activities may 

also be constrained by the availability of rig crews, shore-based facilities, risers, and other equipment.

The scenario for a CPA proposed action assumes that an average exploration well will require 30-120 

(mean of 60) days to drill. The actual time required for each well depends on a variety of factors, 

including the depth of the prospect’s potential target zone, the complexity of the well design, and the 

directional offset of the wellbore needed to reach a particular zone. This scenario assumes that the 

average exploration or delineation well depth will be approximately 4,572-7,010 m (15,000-23,000 ft) 

below the mudline (i.e., surface of the seafloor).

Some delineation wells may be drilled using a sidetrack technique. In sidetracking a well, a portion 

of the existing wellbore is plugged back to a specific depth, directional drilling equipment is installed, and 

a new wellbore is drilled to a different geologic location. The lessee may use this technology to better 

understand 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 (i.e., an actual discovery and/or confirmation of hydrocarbons). Some recent 

ultra-deepwater exploration wells (>6,000 ft [1,829 m] water depth) in the GOM have been reported to 

cost upwards of $200 million. The actual cost for each well depends on a variety of factors, including the 

depth of the prospect’s potential target zone, the complexity of the well design, and the directional offset 

of the wellbore needed to reach a particular zone.

Subpart D of BSEE’s regulations (30 CFR part 250) specifies requirements for drilling activities. 

Refer to Chapter 1.3.1 of this Supplemental EIS, Chapter 1.3.1 and Table 1-2 of the 2012-2017 

WPA/CPA Multisale EIS, and Chapter 1.3.2 of the WPA 233/CPA 231 Supplemental EIS, which provide 

a summary of new and updated safety requirements.

Tables 3-2 through 3-4 show the estimated range of exploration and delineation wells by waterdepth range for the CPA typical lease sale cases; WPA, CPA, and EPA total OCS Program case; and CPA 

cumulative cases, respectively.

CPA Proposed Action Scenario (Typical Lease Sale): BOEM estimates that 168-329 exploration and

delineation wells would be drilled as a result of the CPA proposed action. Table 3-2 shows the estimated 

range of exploration and delineation wells by water-depth range. Greater than 50 percent of the projected 

wells for the CPA proposed action are expected to be on the continental shelf (0-200 m [0-656 ft] water 

depth), and fewer than 50 percent are expected in intermediate water-depth ranges and deeper (>200 m; 

656 ft).

OCS Program Cumulative Scenario (WPA, CPA, and EPA): BOEM estimates that 6,910-9,827 

exploration and delineation wells would be drilled in the WPA, CPA, and EPA as a result of all past OCS 

lease sales and projected activity for future lease sales associated with this Five-Year Program. Tables 

3-3 and 3-4 of this Supplemental EIS and Table 3-6 of the 2012-2017 WPA/CPA Multisale EIS show the 

estimated range of exploration and delineation wells by water-depth range. Of these wells, approximately

55 percent are expected to be on the continental shelf (0-200 m [0-656 ft] water depth) and approximately 

45 percent are expected in intermediate water-depth ranges and deeper (>200 m; 656 ft). Note that 
3-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

offshore and onshore impact-producing factors and scenarios associated with a WPA or an EPA proposed 

action (i.e., a typical lease sale that would result from a proposed action within the WPA or EPA), as well 

as OCS Program activity resulting from past and future lease sales in the WPA or EPA are disclosed in 

the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and EPA 225/226 EIS.

3.1.1.3. Development and Production

Development and Production Drilling

Chapter 3.1.1.3.1 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS describe in detail development and production drilling and development operations and coordination 

documents.

Delineation and production wells are sometimes collectively termed development wells. A 

development well is designed to extract resource from a known hydrocarbon reservoir. After a discovery, 

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 will 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 results in a dry hole, the operator permanently abandons the well without 

delay.

When the decision is made to complete the well, a new stage of activity begins. Completing a well 

involves preparing the well for production. BOEM estimates that approximately 90 percent of 

development wells will become producing wells. The typical process includes setting and cementing the 

production casing, installing some downhole production equipment, perforating the casing and 

surrounding cement, treating the formation, setting a gravel pack (if needed), and installing production 

tubing. One form of formation treatment is known as “fracking.” Fracking involves pressurizing the well 

to force chemicals or mechanical agents into the formation. Mechanical agents, such as sand or small 

microspheres (tiny glass beads), can be used to prop open the created factures that act as conduits to 

deliver hydrocarbons to the wellbore. Well treatment chemicals are commonly used to improve well 

productivity. For example, acidizing a reservoir to dissolve cementing agents and improve fluid flow is 

the most common well treatment in the GOM. After a production test determines the desired production 

rate to avoid damaging the reservoir, the well is ready to go online and produce.

The chief planning document that lays out an operator’s specific intentions for development is the 

development operations coordination document (DOCD). The range of postlease development plans is 

discussed in Chapter 1.5 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. Table 3-2 shows the estimated range of development wells and production structures 

by water-depth subarea for a CPA proposed action.

CPA Proposed Action Scenario (Typical Lease Sale): It is estimated that 215-417 development and 

production wells will be drilled as a result of a CPA proposed action. 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 is more evenly distributed throughout the water-depth ranges, with the greatest number of 

wells being forecasted for water depths >2,400 m (7,874 ft), whereas 66-75 percent of the gas wells are 

projected to be drilled on the continental shelf (0-200 m [0-656 ft] water depth).

OCS Program Cumulative Scenario (WPA, CPA, and EPA): It is estimated that 8,530-12,180 

development and production wells will be drilled in the WPA, CPA, and EPA as a result of the proposed 

lease sales and all OCS activity associated with previous lease sales. Table 3-3 shows the estimated 

range of development wells by water depth.

Note that offshore and onshore impact-producing factors and scenarios associated with a WPA or an 

EPA proposed action (i.e., a typical lease sale that would result from a proposed action within the WPA 

or EPA as well as OCS Program activity resulting from past and future lease sales in the WPA or EPA) 

are disclosed in the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and EPA 225/226 EIS.
Impact-Producing Factors and Scenario 3-9 

Infrastructure Emplacement/Structure Installation and Commissioning Activities

Chapter 3.1.1.3.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail infrastructure

emplacement/structure installation and commissioning activities.

Bottom-founded or floating structures may be placed over development wells to facilitate production 

from a prospect. These structures provide the means to access and control the wells. They serve as a 

staging area to process and treat produced hydrocarbons from the wells, initiate export of the produced 

hydrocarbons, conduct additional drilling or reservoir stimulation, conduct workover activities, and carry 

out eventual abandonment procedures. There is a range of offshore infrastructure installed for 

hydrocarbon production. Among these are pipelines, fixed and floating platforms, caissons, well 

protectors, casing, wellheads, and conductors.

CPA Proposed Action Scenario (Typical Lease Sale): It is estimated that 35-67 production structures 

will be installed as a result of a CPA proposed action. Table 3-2 shows the projected number of structure 

installations for a CPA proposed action by water-depth range. About 80 percent of all the production 

structures installed for a CPA proposed action are projected to be on the continental shelf (0-60 m; 

0-197 ft).

OCS Program Cumulative Scenario (WPA, CPA, and EPA): It is estimated that 1,435-2,026 

production structures would be installed in the WPA, CPA, and EPA as a result of the proposed lease 

sales and all OCS activity associated with previous lease sales. Tables 3-2 and 3-3 of this Supplemental 

EIS and Table 3-6 of the 2012-2017 WPA/CPA Multisale EIS show the projected number of structure 

installations by water-depth range for the OCS Program.

Note that offshore and onshore impact-producing factors and scenarios associated with a WPA or an 

EPA proposed action (i.e., a typical lease sale that would result from a proposed action within the WPA 

or EPA), as well as OCS Program activity resulting from past and future lease sales in the WPA or EPA 

are disclosed in the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and EPA 225/226 EIS.

Bottom Area Disturbance

Chapter 3.1.1.3.2.1 of the 2012-2017 WPA/CPA Multisale EIS describes in detail bottom area 

disturbances. Structures emplaced or anchored on the OCS to facilitate oil and gas exploration and 

production include drilling rigs or MODU’s (jack-ups, semisubmersibles, and drillships), pipelines, and 

fixed surface, floating, and subsea production systems are described in Chapter 3.1.1.3 of this 

Supplemental EIS and in Chapters 3.1.1.3.1 and 3.1.1.3.2 of the 2012-2017 WPA/CPA Multisale EIS. 

The emplacement or removal of these structures disturbs small areas of the sea bottom beneath or 

adjacent to the structure. If mooring lines of steel, chain, or synthetic polymer are anchored to the sea 

bottom, areas around the structure can also be directly affected by their emplacement. This disturbance 

includes physical compaction or crushing beneath the structure or mooring lines and the resuspension and 

settlement of sediment caused by the activities of emplacement. Movement of floating types of facilities 

will also cause the movement of the mooring lines in its array. Small areas of the sea bottom will be 

affected by this kind of movement. Impacts from bottom disturbance are of concern near sensitive areas 

such as topographic features, pinnacles, low-relief live bottom features, chemosynthetic communities, 

high-density biological communities in water depths ≥400 m (1,312 ft), and archaeological sites.

Sediment Displacement

Chapter 3.1.1.3.2.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail sediment 

displacement. Displaced sediments are those that have been physically moved “in bulk.” Displaced 

sediments will cover or bury an area of the seafloor, while resuspended sediments will cause an increase 

in turbidity of the adjacent water column. Resuspended sediments eventually settle, covering the 

surrounding seafloor. Resuspended sediments may include entrained heavy metals or hydrocarbons.

Infrastructure Presence

Chapter 3.1.1.3.3 of the 2012-2017 WPA/CPA Multisale EIS describes in detail impact-producing 

factors due to infrastructure presence. The installation and maintenance of infrastructure may include, but 

is not limited to, the following: 
3-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

• anchoring;

• offshore production systems;

• space-use requirements (deployment of survey equipment or bottom-founded 

production equipment);

• aesthetic quality (presence and visibility of equipment, vessels, and air traffic); and

• workovers and abandonments.

3.1.1.4. Operational Waste Discharged Offshore

Chapter 3.1.1.4 of the 2012-2017 WPA/CPA Multisale EIS describes in detail impacting factors due 

to operational wastes discharged offshore and Chapter 3.1.1.4 of the WPA 233/CPA 231 Supplemental 

EIS provides a summary as well as detailed updated information on more recent, stricter regulations 

regarding vessel discharges. Operational wastes discharged offshore include the following:

• drilling muds and cuttings;

• produced waters; 

• well treatment, workover, and completion fluids;

• production solids and equipment;

• bilge, ballast, and fire water;

• cooling water;

• deck drainage;

• treated domestic and sanitary wastes; 

• minor discharges; 

• vessel operational discharges; and

• distillation and reverse osmosis brine.

BOEM maintains records of the volume of 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 2000-2012 is summarized by water depth in Table 3-5, with 

new data provided for the years 2010-2012. The total volume for all water depths during this 12-year 

period ranged from 489.0 to 648.2 MMbbl, with the largest contribution (69-88%) coming from 

operations on the shelf. The total volume of produced water generally decreased after 2004, reflecting an

overall decrease in contributions from 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 2012, the contribution from these operations (deep and 

ultra-deepwater together) increased from 6 percent (37.8 MMbbl) to 27 percent (138.2 MMbbl) of the 

total produced-water volume (calculated from data in Table 3-5). The updated annual amounts and depth 

distributions of produced water discharged by depth are within the range of or similar to data presented in 

the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. Thus, this new 

information did not change the validity of the operational wastes discussion previously presented. 

3.1.1.5. Air Emissions

In 1990, pursuant to Section 328 of the Clean Air Act Amendments and following consultation with 

the Commandant of the U.S. Coast Guard (USCG) and the Secretary of the Interior, the United States 

Environmental Protection Agency (USEPA) assumed air quality responsibility for the OCS waters in the 

GOM east of longitude 87.5o W., and this Agency retained National Ambient Air Quality Standards 
Impact-Producing Factors and Scenario 3-11

(NAAQS) air quality jurisdiction for OCS operations west of the same longitude in the GOM. Air quality 

regulations are under a comprehensive review in 2014 to replace obsolete provisions and to ensure that 

updates in regulations are following improvements in scientific and technological information.

There are many air emissions sources related to OCS oil and gas exploration, development, and 

production in the GOM. During the exploration stage, most of the OCS non-platform emissions are from 

combustion from the equipment used on a drilling rig or from fuel usage of a support vessel. During the 

production stage, platform emission sources include boilers, diesel engines, combustion flares, fugitives, 

glycol dehydrators, natural gas engines, turbines, pneumatic pumps, pressure/level controllers, storage 

tanks, cold vents, and others. During the development stage, most of the OCS non-platform emissions are 

from fuel usage of support or survey vessels to lay pipelines, install facilities, or map geologic formations 

and seismic properties.

Pollutants released by OCS sources include the NAAQS pollutants CO, NOx, PM, and SO2. 

Pollutants also released by OCS sources (NOx and VOC) are precursors to ozone, which is formed by 

photochemical reactions in the atmosphere and is another NAAQS pollutant. Lastly, OCS sources release 

greenhouse gas emissions, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). 

The Year 2008 Gulfwide Emissions Inventory Study (Wilson et al., 2010) indicates that, for calendar 

year 2008, OCS oil and gas production platforms and non-platform sources emit the majority of criteria 

pollutants and greenhouse gases in the GOM on the OCS, with the exception of PM and SO2 (primarily 

emitted from commercial marine vessels) and N2O (from biological sources). The OCS oil and gas 

production platform and non-platform sources account for 93 percent of the total CO emissions, 

74 percent of NOx emissions, 76 percent of VOC emissions, and 99 percent of the CH4 emissions, and 

84 percent of the CO2 emissions. Natural gas engines on platforms represented the largest CO emission 

source, accounting for 60 percent of the total estimated CO emissions; and support vessels were the 

highest emitters of NOx, accounting for 35 percent of the total estimated emissions. Oil and natural gas 

production platform vents and fugitive sources account for the highest percentage of VOC and CH4

emissions. Support vessels (29% of total emissions), production platform natural gas turbines (15% of 

total emissions), and drilling rigs (12% of total emissions) emit the majority of the CO2 emissions.

3.1.1.6. Noise

Noise associated with OCS oil and gas development results from seismic surveys, the operation of 

fixed structures such as offshore platforms and drilling rigs, and helicopter and service-vessel traffic. 

Noise generated from these activities can be transmitted through both air and water, and may be longlived or temporary. Offshore drilling and production involves various activities that produce a composite 

underwater noise field. The intensity level and frequency of the noise emissions are highly variable, both 

between and among the various industry sources. Noise from proposed OCS activities may affect 

resources near the activities. Whether a sound is or is not detected by marine organisms depends both on 

the acoustic properties of the source (spectral characteristics, intensity, and transmission patterns) and the 

sensitivity of the hearing system in the marine organism. Extreme levels of noise can cause physical 

damage or death to an exposed animal and, in limited circumstances, can cause “take” of endangered and 

threatened species as defined in the Federal Endangered Species Act. Source levels well above hearing 

thresholds can damage hearing or induce behavioral changes (Richardson et al., 1995). Chapter 3.1.1.6 of 

the 2012-2017 WPA/CPA Multisale EIS describes in detail noise impact-producing factors associated 

with OCS oil and gas development.

3.1.1.7. Major Sources of Oil Inputs in the Gulf of Mexico

Petroleum hydrocarbons can enter the GOM from a wide variety of sources. The major sources of oil 

inputs in the GOM are natural seepage, permitted produced-water discharges, land-based discharges, and 

accidental spills. Numerical estimates of the contributions for these sources to the GOM coastal and 

offshore waters are shown in Tables 3-8 and 3-9 of the 2012-2017 WPA/CPA Multisale. Chapter 3.1.1.7 

of the 2012-2017 WPA/CPA Multisale EIS describes in detail major sources of oil inputs in the Gulf of 

Mexico, including natural seepage, produced water, land-based discharges, and spills.

Chapter 3.1.1.7.4 of the 2012-2017 WPA/CPA Multisale EIS also describes in detail the following 

information related to oil spills: trends in reported spill volumes and numbers; projections of future spill 
3-12 Central Planning Area Lease Sales 235, 241, and 247 EIS

events; OCS oil- and gas-related offshore spills; non-OCS oil- and gas-related offshore spills; OCS oiland gas-related coastal spills; non-OCS oil- and gas-related coastal spills; and other sources of oil.

The most recent version of the USCG report, “Polluting Incidents In and Around U.S. Waters, A 

Spill/Release Compendium: 1969-2011” was published in December 2012 (U.S. Dept. of Homeland 

Security, CG, 2012a). This document summarizes spills reported to the USCG that occurred on navigable 

waters, including rivers, lakes and harbors, the territorial seas (0-3 mi [0-5 km] from the coastline), the

contiguous zone (3-12 mi [5-19 km] from the coastline), and the marine environment. The data include 

over 174 different petroleum and nonpetroleum oils and over 50 source types, including barges, tanks, 

pipelines, and waterfront facilities. These data augment information included in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. According to the USCG report, 

crude oil and heavy fuel oil were spilled in the greatest volumes. Most spills and spill volume occurred in 

the GOM coastal waters and the western rivers system, which includes the Mississippi, Ohio, and 

Arkansas Rivers. For the 37-year period ending in 2009, the USCG’s databases for all U.S. waters 

contained investigations of more than 270,000 oil spills. The total spill amount during that period was 

240.7 million gallons. The majority of spills through the years of this report involved discharges between 

1 and 100 gallons. Thus, the oil discharged from the Macondo well (the source of the Deepwater Horizon

oil spill in April 2010) represents the equivalent of 86 percent of all oil discharged in the preceding 

37 years (U.S. Dept. of Homeland Security, CG, 2012a).

From 1991 through 2011, non-tank vessels accounted for 75.4 percent of the number of spills that 

occurred in U.S. waters (U.S. Dept. of Homeland Security, CG, 2012a). Historically, tank vessels (ships 

and barges) accounted for most of the volume spilled in U.S. waters. However, since passage of the Oil 

Pollution Act of 1990, the distribution of spill volumes has shifted away from tank vessel sources. For 

example, at the national level for the years 1999 through 2011, 29 percent of the volume of oil spilled 

came from tank vessels (e.g., ships/barges) compared with 41 percent from facilities and other 

non-vessels (the Macondo well was not included). Furthermore, in 2010, the largest oil spill in U.S. 

waters emanated from the exploratory Macondo oil well in the Gulf of Mexico. However, with the 

exception of rare but extreme incidents such as the Deepwater Horizon oil spill, the overall number and 

volume of spills in U.S. waters has been on a steady downward trend since 1973. In fact, 2010, the year 

of the largest recorded spill in U.S. waters, was followed by a record low annual volume of 210,270 

gallons in 2011 (U.S. Dept. of Homeland Security, CG, 2012a).

Specifically, in 2010, the GOM region experienced 455 spills having a combined volume of 

206,990,317 gallons, representing 15.1 percent of the total number of U.S. waterways spills and 

99.7 percent of the total spillage volume in the U.S. waterways for that year. In 2011, 498 spills having a 

combined volume of 20,276 gallons occurred in the GOM, representing 16.2 percent of the total number 

of U.S. waterways spills and 9.6 percent of the total spillage volume in the U.S. waterways for that year 

(U.S. Dept. of Homeland Security, CG, 2012a). Table 3-6 illustrates that the total number of spill 

incidents occurring per year in the GOM has generally declined during this period of time from a high of 

1,728 reported incidents in 2001 to less than 523 yearly spill incidents reported since 2008.

3.1.1.8. Offshore Transport

Offshore transport includes both movements of oil and gas products as well as the transportation of 

equipment and personnel. Chapter 3.1.1.8 of the 2012-2017 WPA/CPA Multisale EIS describes in detail 

sources of offshore transport and proposed action scenarios, including pipelines (installation and 

maintenance; landfalls), barges, oil tankers and projections related to floating production, storage, and 

offloading systems (FPSO’s), service vessels, and helicopter trips. Updated information on total traffic 

(OCS- and non-OCS Program-related) on navigation channels for 2011 can be found in Table 3-7. This 

new information did not alter the projections or conclusions made in the 2012-2017 WPA/CPA Multisale 

EIS or WPA 233/CPA 231 Supplemental EIS.

3.1.1.9. Safety Issues

Safety issues related to OCS oil and gas development include the presence of hydrogen sulfide and 

sulfurous petroleum and shallow hazards. These safety issues are described in detail in Chapters 3.1.1.9.1 

and 3.1.1.9.2 of the 2012-2017 WPA/CPA Multisale EIS. Technologies continue to evolve to meet the 
Impact-Producing Factors and Scenario 3-13

technical, environmental, and economic challenges of deepwater development. These new and unusual 

technologies are described in Chapter 3.1.1.9.3 of the 2012-2017 WPA/CPA Multisale EIS.

3.1.1.10.Decommissioning and Removal Operations

During exploration, development, and production operations, the seafloor around activity sites within 

a proposed lease sale area becomes the repository of temporary and permanent equipment and structures. 

In compliance with Section 22 of BOEM’s Oil and Gas Lease Form (BOEM-2005) and BSEE regulations 

(30 CFR §§ 250.1710 et seq.—Permanently Plugging Wells and 30 CFR §§ 250.1725 et seq.—Removing 

Platforms and Other Facilities), lessees are required to remove all seafloor obstructions from their leases 

within 1 year of lease termination or relinquishment. These regulations require lessees to sever bottomfounded structures and their related components at least 5 m (15 ft) below the mudline to ensure that 

nothing would be exposed that could interfere with future lessees and other activities in the area. The 

structures are generally grouped into two main categories depending upon their relationship to the 

platform/facilities (e.g., piles, jackets, caissons, templates, mooring devises, etc.) or the well (e.g., 

wellheads, casings, casing stubs). Decommissioning and removal operations, including the CPA 

proposed action and OCS Program scenarios, are described in detail in Chapter 3.1.1.10 of the 2012-2017 

WPA/CPA Multisale EIS.

3.1.2. Coastal Impact- Producing Factors and Scenario

3.1.2.1. Coastal Infrastructure

Chapter 3.1.2 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS 

discuss coastal impact-producing factors and provide scenario projections for onshore coastal 

infrastructure that may potentially result from a single CPA proposed action in the Five-Year Program. 

These coastal impact-producing factors could potentially affect the biological, physical, and 

socioeconomic resources of the Gulf of Mexico. Chapter 3.1.2.1 of the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS provide summaries as well as detailed updated 

information on OCS oil- and gas-related coastal infrastructure types, which include the following:

• service bases; 

• helicopter hubs;

• platform fabrication yards;

• shipbuilding and shipyards;

• pipecoating facilities and yards;

• refineries; 

• gas processing plants; 

• liquefied natural gas (LNG) facilities; 

• pipeline shore facilities, barge terminals, and tanker port areas; 

• coastal pipelines; 

• coastal barging; and

• navigation channels (see updated information on navigation channels in Table 3-7). 

This OCS oil- and gas-related infrastructure has been developed over many decades, and it is an 

extensive and mature system that provides support for offshore activities. The expansive presence of this 

coastal infrastructure is the result of long-term industry trends and is not subject to rapid fluctuations. 

BOEM projects no new coastal infrastructure with the exception of 0-1 new pipeline landfall and 0-1 new 

gas processing facility as a result of an individual proposed action. Existing solid-waste disposal

infrastructure is projected to be adequate to support both existing and projected offshore oil and gas 
3-14 Central Planning Area Lease Sales 235, 241, and 247 EIS

drilling and production needs. Detailed descriptions of the baseline affected environment for land use and 

coastal infrastructure in the CPA are provided in Chapter 4.2.1.23.1.1 of this Supplemental EIS, Chapter 

4.2.1.23.1.1 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.23.1 of the WPA 233/CPA 

231 Supplemental EIS.

The U.S. Energy Information Administration updates national energy projections annually, including 

refinery capacity. A crude oil refinery is a group of industrial facilities that turns crude oil and other 

inputs into finished petroleum products. A refinery’s capacity refers to the maximum amount of crude oil 

designed to flow into the distillation unit of a refinery, also known as the crude unit. Most of the GOM 

region’s refineries are located in Texas and Louisiana (Table 3-13 of the 2012-2017 WPA/CPA Multisale 

EIS). Texas has 26 operable refineries, with an operating capacity of over 4.6 MMbbl/day, which is close 

to 28 percent of the total U.S. capacity. Louisiana follows closely behind Texas, with 18 operable 

refineries, with an operational capacity of over 3.0 MMbbl/day, which is 18 percent of the total U.S. 

capacity (USDOE, Energy Information Administration, 2013c). 

For all domestic refineries, distillation capacity is expected to stay at a steady rate of 17.5 MMbbl/day 

over the 40-year period (USDOE, Energy Information Administration 2013c). For many years financial, 

environmental, and legal considerations have prevented the construction of new refineries in the U.S., 

thereby forcing companies to expand and retrofit existing facilities. Domestic refinery expansions are 

largely being driven by unconventional sources of oil, primarily Canadian oil sands (Sreekumar, 2013). 

The Canadian heavy crude is cheaper to purchase but costlier to refine, and many refineries planning to 

take advantage of the newest discoveries are expanding their facilities to handle the higher volumes of 

impurities associated with heavier crude oils (Rigzone, 2013).

In 2008, projections indicated that the U.S. would need to ramp up its natural gas imports, and 

industry began constructing LNG containers along Gulf ports to accommodate the influx in imports 

(Helman, 2013). In 2013, onshore unconventional natural gas production increased to the point that 

existing Gulf Coast LNG facilities are seeking to export natural gas to foreign countries. In 2011, 

Cheniere’s Sabine Pass, Louisiana, facility received approval from the Department of Energy to export to 

any country in the world (Helman, 2013; U.S. Dept. of Energy, Federal Energy Regulatory Commission, 

2013). Twelve additional project sponsors have applied to DOE for authorization to export domestically 

produced LNG to free trade agreement and non-free trade agreement countries (Dismukes, 2013a and b; 

U.S. Dept. of Energy, Federal Energy Regulatory Commission, 2013).

3.1.2.2. Discharges and Wastes

Chapter 3.1.2.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail coastal discharges and 

wastes and Chapter 3.1.2.2 of the WPA 233/CPA 231 Supplemental EIS provides a summary and updates 

to these coastal discharges and wastes, which include the following:

• disposal and storage facilities for offshore operational wastes; 

• onshore facility discharges; 

• coastal service-vessel discharges; 

• offshore wastes disposed onshore; and

• beach trash and debris. 

The USEPA currently regulates vessel discharges with the Vessel General Permit (VGP), which is a 

Clean Water Act National Pollutant Discharge Elimination System (NPDES) permit that authorizes, on a 

nationwide basis, discharges incidental to the normal operation of nonmilitary and nonrecreational vessels 

greater than or equal to 79 ft (24 m) in length. On March 28, 2013, USEPA reissued the 2008 VGP for 

another 5 years; the reissued permit, the 2013 VGP, now contains numeric ballast water discharge limits 

for most vessels. The VGP also contains more stringent effluent limits for oil-to-sea interfaces and 

exhaust gas scrubber washwater. There is also a Small Vessel General Permit (sVGP), which if finalized, 

would authorize discharges incidental to the normal operation of nonmilitary and nonrecreational vessels 

less than 79 ft (24 m) in length and commercial fishing vessels (USEPA, 2013a). 

BOEM’s policy regarding marine debris prevention is outlined in NTL 2012-G01, “Marine Trash and 

Debris Awareness and Elimination.” This NTL instructs OCS operators to post informational placards 
Impact-Producing Factors and Scenario 3-15

that outline the legal consequences and potential ecological harms of discharging marine debris. The 

NTL also states that OCS workers should complete annual marine debris prevention training and instructs 

operators to develop a certification process for the completion of this training by their workers. These 

various laws, regulations, and NTL’s will likely minimize the discharge of marine debris from OCS 

operations.

3.2. IMPACT-PRODUCING FACTORS AND SCENARIO—ACCIDENTAL EVENTS

3.2.1. Oil Spills

Oil spills are unplanned accidental events, and historical data provide the most relevant data for use in 

predicting future oil-spill frequency and volume in the GOM on a programmatic level. The following 

sections discuss spill prevention and spill response, and analyze the risk of spills that could occur as a 

result of activities associated with a CPA proposed action. Public input through scoping meetings and 

Federal and State agencies’ input through consultation and coordination indicate that oil spills are 

perceived to be a major issue, especially in the wake of the Deepwater Horizon oil spill. The following 

sections analyze the risk of spills that could occur as a result of a typical CPA proposed action, as well as 

information on the number and sizes of spills from non-OCS sources. Refer to Appendix B for the 

“Catastrophic Spill Event Analysis.”

3.2.1.1. Spill Prevention

In the 1980’s, this Agency established comprehensive pollution-prevention requirements that include 

redundant safety systems, as well as inspection and testing requirements to confirm that these devices are 

working properly (Chapter 1.5). With the exception of rare incidents such as the Deepwater Horizon oil 

spill, an overall reduction in spill volume had occurred during the previous 40 years, while oil production 

had generally increased. A characterization of spill rates, average and median volumes from 1995 to 

2009 compared with characterization of spill rates, average and median volumes from 1996 to 2010 

(latest analysis available), which includes the Deepwater Horizon oil spill, is provided in Update of 

Occurrence Rates for Offshore Oil Spills (Anderson et al., 2012). BOEM attributes this overall reduction 

in spill volume to its operational requirements, ongoing efforts by the oil and gas industry to enhance 

safety and pollution prevention, and the evolution and improvement of offshore technology.

3.2.1.2. Past OCS Spills

BOEM’s spill-event database includes records of past spills from activities that are regulated by 

BOEM. These data include oil spills >1 bbl that occurred in Federal waters from OCS facilities and 

pipeline operations. Spills from facilities include spills from drilling rigs, drillships, and storage, 

processing, or production platforms that occurred during OCS drilling, development, and production 

operations. Spills from pipeline operations are those that have occurred on the OCS and are directly 

attributable to the transportation of OCS oil. Anderson et al. (2012) was utilized in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS to characterize spill rates and to 

provide analysis for average and median volumes. The Anderson et al. (2012) analysis examined spill 

data for the period 1964 to 2010, including the Deepwater Horizon oil spill.

A search of BSEE’s oil-spill database (USDOI, BSEE, 2013a) was performed to assess new spill 

information during the 2011-2012 period and to provide an update to the Anderson et al. (2012) analysis. 

During the period 2011 to 2012, there were 35 spills from OCS oil and gas activities of <1,000 bbl in size. 

The breakdown of the 35 spills <1,000 bbl that occurred in 2011 and 2012 from OCS oil and gas 

activities into size classes is as follows: 19 spills of 1-4 bbl; 5 spills of 5-9 bbl; 9 spills of 10-49 bbl; 

1 spill of 50-99 bbl; 1 spill of 100-999 bbl; and 0 spills of ≥1,000 bbl. The combined total of oil spilled in 

these 35 events was 815 bbl. The BSEE database (USDOI, BSEE, 2013a) indicated that there were two

spills (one in 2011 and one in 2012) that were between 50 and 500 bbl in size, both of which occurred in 

the CPA. The spill in 2011 equaled 67 bbl and was the result of equipment failure from a platform leak 

located in Garden Banks Block 72. The spill in 2012 was estimated at 480 bbl and resulted from an 

explosion on a platform located in West Delta Block 32. However, the 2012 spill is still under 

investigation and observations collected during the spill suggest that the spill volume was actually much 

smaller. In summary, two spills >50 bbl occurred in the CPA during the period 2011 to 2012. This is an 
3-16 Central Planning Area Lease Sales 235, 241, and 247 EIS

outcome that is well within the range of spills estimated to occur in Table 3-12 of the 2012-2017 

WPA/CPA Multisale EIS, which serves as an estimate of the number and size of spills likely to occur as a 

result of a CPA proposed action over a 40-year time period. Thus, the additional information provided by 

the review of BSEE’s oil-spill database (USDOI, BSEE 2013a) did not change the validity of the scenario 

previously presented. 

The majority of the 2011-2012 spills are attributed to OCS platforms/rigs, followed by vessels, and 

lastly by OCS pipelines. These data were compared with the estimated number and sizes of spills 

presented in Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS (derived in part from Anderson et al., 

2012), and it was found that the new spill data were well within the spill numbers estimated in the 

previous document. The new data also concurred with the previous finding that the most likely source of 

a spill would be from platforms, rigs, or vessels. Thus, a review of recent information does not change 

the risk analyses for spills <1,000 bbl previously provided in the 2012-2017 WPA/CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS. As estimated in Table 3-12 of the 2012-2017 WPA/CPA 

Multisale EIS, no spills have occurred in the ≥1,000-bbl size class during 2011 and 2012.

3.2.1.3. Characteristics of OCS Oil

The physical and chemical properties of oil greatly affect its transport and its ultimate fate in the 

environment and determine the following: how oil will behave on the water surface (surface spills) or in 

the water column and sediments (subsea spills); the persistence of the slick on the water; the type and 

speed of weathering processes; the degree and mechanisms of toxicity; the effectiveness of containment 

and recovery equipment; and the ultimate fate of the spill residues. Crude oils are a natural mixture of 

hundreds of different compounds, with liquid hydrocarbons accounting for up to 98 percent of the total 

composition. The chemical composition of crude oil can vary significantly from different producing 

areas; thus, the exact composition of oil being produced in OCS waters varies throughout the Gulf. The 

American Petroleum Institute gravity (API gravity) is a measure of the relative density of oil compared 

with water and is expressed in degrees (°). Oils with an API gravity <10 are heavier and typically sink, 

whereas oils with an API gravity >10 are lighter and typically float. Following an oil spill, the 

composition of the released oil can change substantially due to weathering processes such as evaporation, 

emulsification, dissolution, and oxidation. More details on the properties and persistence of different 

types of oils are provided in Table 3-7 of the WPA 233/CPA 231 Supplemental EIS.

Extensive laboratory testing has been performed on various oils from the GOM to determine their 

physical and chemical characteristics. For example, numerous oils collected from the GOM (U.S. waters) 

are included in Environment Canada’s (2013) oil properties database. The database provides details of an 

oils chemical composition including hydrocarbon groups (i.e., saturates, aromatics, resins, asphaltenes), 

VOC’s (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°. Since the 

Deepwater Horizon oil spill, new data have been analyzed from the approximately 450 deepwater 

exploration plans (EP’s) and DOCD’s that were submitted to BOEM/BSEE. Statistics on these API 

gravities result in a similar range (16° to 58°) as previously reported, with a mean value of 36°. These 

new data corroborate the information previously presented in the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS.

3.2.1.4. Overview of Spill Risk Analysis

There are many factors that BOEM evaluates to determine the risk of impact occurring from an oil 

spill, including likely spill sources, likely spill locations, likely spill sizes, the likelihood and frequency of 

occurrence for different size spills, timeframes for the persistence of spilled oil, volumes of oil removed 

due to weathering and cleanup, and the likelihood of transport by wind and waves resulting in contact to 

specified environmental features. Sensitivity of the environmental resources and potential effects are 

addressed in the analyses for the specific resources of concern (Chapter 4.1). BOEM uses data on past 

OCS production and spills, along with estimates of future production, to evaluate the risk of future spills. 

Additionally, BOEM uses a numerical model to calculate the likely trajectory of spills (i.e., transport 

pathways) and analyzes historical data of occurrence rates for oil spills (refer to Anderson et al., 2012) to 

make projections of future oil-spill frequency and size. A more detailed description of the spill risk 

analysis and the trajectory model, called OSRA (oil-spill risk analysis) model, were provided in Chapter 3 
Impact-Producing Factors and Scenario 3-17

of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, as well as in the 

Ji et al. (2012) OSRA report. Appendix C of this Supplemental EIS also contains the OSRA model’s 

catastrophic spill event results to estimate the risks associated with a possible future low-probability 

catastrophic or high-volume, long-duration oil spill.

The OSRA model results and estimated spill size/frequency tables as presented and discussed in the 

2012-2017 WPA/CPA Multisale EIS remain applicable because the basic assumptions inherent in the 

model and calculations are still valid. The latest analysis available for the characterization of spill rates 

and for average and median volumes (Anderson et al., 2012) inputted into the model is still valid because 

the more recent small OCS spills (2011-2012) were within spill scenario estimates developed using the 

past data. In addition, the physical forcing (e.g., ocean currents and wind fields) and environmental 

resources input (e.g., locations and seasonality of various biological resources) to the OSRA model are 

still representative of our current state of knowledge regarding both ocean modeling and potential 

environmental resources at risk. Numerous efforts are underway since the Deepwater Horizon oil spill to 

further improve trajectory modeling in the Gulf of Mexico, including several BOEM environmental 

studies (e.g., refer to Section 4.2 in Ji et al., 2013). However, the results of these new research activities 

are not yet available or fully tested for incorporation into BOEM’s oil-spill risk analysis. Thus, new 

information did not change the results of previous spill risk analyses provided in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

The following discussions provide separate risk information for offshore and coastal spills that may 

result from a CPA proposed action. This analysis is divided into discussions of offshore spills ≥1,000 bbl, 

offshore spills <1,000 bbl, and coastal spills of any spill volume. Only spills ≥1,000 bbl are addressed 

using OSRA because smaller spills typically do not persist long enough to be simulated by trajectory 

modeling.

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

Chapter 3.2.1.5 of the 2012-2017 WPA/CPA Multisale EIS addressed the risk of spills ≥1,000 bbl 

that could occur from accidents associated with activities resulting from a CPA proposed action. The risk 

analyses included the following:

• estimated number of offshore spills ≥1,000 bbl and probability of occurrence;

• most likely source of offshore spills ≥1,000 bbl;

• most likely size of an offshore spill ≥1,000 bbl;

• fate of offshore spills ≥1,000 bbl;

• transport of spills ≥1,000 bbl by winds and currents;

• length of coastline affected by offshore spills ≥1,000 bbl; and

• likelihood of an offshore spill ≥1,000 bbl occurring and contacting modeled locations 

of environmental resources.

Specifically, for a CPA proposed action, the mean number of spills was estimated at <1-1 spill (mean 

equal to 0.5-1.0) total from both OCS platforms and OCS pipelines, with an overall 41-62 percent chance 

of one or more spills ≥1,000 bbl occurring in the CPA. Based on historical data, the most likely source of 

an offshore spill was determined to be a potential pipeline break at the seafloor.

Because no spills ≥1,000 bbl in size have occurred during 2011-2012, use of Anderson et al. (2012) 

remains applicable and up to date for characterizing spill rates and average and median spill volumes in 

this Supplemental EIS. In terms of weathering, fate, and transport of oil spills in the Gulf of Mexico, a 

variety of ongoing studies are providing more insights in the aftermath of the Deepwater Horizon oil spill. 

For example, recent studies have provided further evidence that the diverse microbial communities in 

both the water column (e.g., Mason et al., 2012) and sediments (Kimes et al., 2013) of the GOM can play

an active role in metabolizing and bioremediating crude oil from offshore spills. Further research is also 

being conducted regarding what impact chemical dispersant application may have on this biodegradation 

process. Other research on oil fates suggests that marine snow formation in the aftermath of a large oil-
3-18 Central Planning Area Lease Sales 235, 241, and 247 EIS

spill event (such as the Deepwater Horizon oil spill) may play a key role in the fate of surface oil (e.g., 

Passow et al., 2012). However, many of the important recent findings related to the quantitative modeling 

of fate and transport of large oil spills in the Gulf of Mexico are part of the ongoing Natural Resource 

Damage Assessment (NRDA) process and have not yet been publicly released. Thus, a review of recent 

information does not change the quantitative risk analyses for spills ≥1,000 bbl previously provided the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. 

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

Chapter 3.2.1.6 of the 2012-2017 WPA/CPA Multisale EIS addressed the the risk of spills <1,000 bbl 

resulting from a CPA proposed action. Analysis of historical data shows that most offshore OCS oil 

spills fall within this category, with the majority of spills falling within the significantly smaller range of 

≤1 bbl (Anderson et al., 2012). Although spills of ≤1 bbl amount to 96 percent of all OCS oil- and gasrelated spill occurrences, they have contributed very little to the total volume of oil spilled. The risk 

analyses addressed in Chapter 3.2.1.6 of the 2012-2017 WPA/CPA Multisale EIS included the following:

• estimated number of offshore spills <1,000 bbl and total volume of oil spilled;

• most likely source and type of offshore spills <1,000 bbl;

• most likely size of offshore spills <1,000 bbl;

• persistence, spreading, and weathering of offshore oil spills <1,000 bbl;

• transport of spills <1,000 bbl by winds and currents; and

• likelihood of an offshore spill <1,000 bbl occurring and contacting modeled locations 

of environmental resources.

A search of BSEE’s oil-spill database (USDOI, BSEE, 2013a) was performed to assess new spill 

information during 2011-2012, a period that was not analyzed in Anderson et al. (2012). During 2011-

2012, there were 35 spills from OCS oil and gas activities of <1,000 bbl in size, totaling 815 bbl overall. 

The breakdown of these spills into size classes is provided in Chapter 3.2.1.2. As noted above, the 2011-

2012 spill data were compared with the estimated number and sizes of spills presented in Table 3-12 of 

the 2012-2017 WPA/CPA Multisale EIS and were found to be well within the spill numbers estimated in 

the previous document. The new data also supported previous findings that the most likely source of a 

spill of <1,000 bbl would be from platforms, rigs, or vessels. Thus, a review of recent information does 

not change the risk analyses for spills <1,000 bbl previously provided in Chapter 3.2.1.6 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

3.2.1.7. Risk Analysis for Coastal Spills

Spills in coastal waters could occur at storage or processing facilities supporting the OCS oil and gas 

industry or from the transportation of OCS-produced oil through State offshore waters and along 

navigation channels, rivers, and through coastal bays. BOEM projects that almost all (>99%) oil 

produced as a result of a CPA proposed action will be brought ashore via pipelines to oil pipeline shore 

bases, stored at these facilities, and eventually transferred via pipeline or barge to Gulf coastal refineries. 

Because oil is commingled at shore bases and cannot be directly attributed to a particular lease sale, this 

this analysis of coastal spills addresses spills that could occur prior to the oil arriving at the initial 

shoreline facility. It is also possible that non-OCS oil may be commingled with OCS oil at these facilities 

or during subsequent secondary transport. Chapter 3.2.1.7 of the 2012-2017 WPA/CPA Multisale EIS 

describes in detail the estimated number and most likely sizes of coastal spills and the likelihood of 

coastal spill contact.

The USCG released a more recent version of the report titled Polluting Incidents In and Around U.S. 

Waters Spill/Release Compendium, 1969-2011, which includes data for the years 2010 and 2011 (U.S. 

Dept. of Homeland Security, CG, 2012a). The updated version of the USCG report included an 

additional 953 spills for 2010 and 2011 in inland, coastal, and OCS waters across the GOM; these spills 
Impact-Producing Factors and Scenario 3-19

were not reported in Chapter 3.2.1.7 of the 2012-2017 WPA/CPA Multisale EIS (U.S. Dept. of Homeland 

Security, CG, 2012a).

The number and most likely spill sizes to occur in coastal waters in the future are expected to 

resemble the patterns that have occurred in the past as long as the level of hydrocarbon use by commercial 

and recreational activities remains the same. Estimates of future coastal spills are based on historical 

spills reported to USCG; consequently, in the GOM region, Louisiana and Texas are the states most likely 

to have a spill ≥1,000 bbl occur in coastal waters. A spill that occurs in Federal waters could also be 

transported to State waters via wind/currents. For offshore spills ≤1000 bbl, only those >50 bbl would be 

expected to have a chance of persisting long enough for the slick to reach coastal waters. Few offshore 

spills 50-1,000 bbl in size are estimated to occur as a result of a proposed action within the proposed CPA 

lease sale area and few of these slicks are expected to occur proximate to State waters. Should a slick 

from such a spill reach coastal waters, the volume of oil remaining in the slick is expected to be small.

3.2.1.8. Risk Analysis by Resource

BOEM previously analyzed the risk to resources from oil spills and oil slicks that could occur as a 

result of a CPA proposed action in the 2012-2017 WPA/CPA Multisale EIS. The risk results were based 

on BOEM’s estimates of likely spill locations, sources, sizes, frequency of occurrence, physical fates of 

different types of oil slicks, and probable transport that were described in more detail in specific spill

scenarios. For offshore spills ≥1,000 bbl, combined probabilities were calculated using the OSRA model, 

which includes both the likelihood of a spill from a proposed action occurring and the likelihood of the oil 

slick reaching areas where known environmental resources exist. The analysis of the likelihood of direct 

exposure and interaction of a resource with an oil slick and the sensitivity of a resource to the oil was 

provided under each resource category in Chapter 4.1.1 of this Supplemental EIS and was provided in 

Chapter 4.1.1 of the WPA 233/CPA 231 Supplemental EIS and in Chapter 3.2.1.8 and Figures 3-8 

through 3-28 of the 2012-2017 WPA/CPA Multisale EIS. Coastal spills were estimated from historic 

counts; the estimate was not a rate tied to an anticipated production volume or a probability.

3.2.1.9. Spill Response

Chapter 3.2.1.9 of the 2012-2017 WPA/CPA Multisale EIS describes in detail offshore spill response. 

Issues discussed related to spill response include offshore response, containment, and cleanup technology; 

and onshore response and cleanup.

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. The following requirements are implemented 

according to BSEE’s regulations at 30 CFR parts 250 and 254:

• requires immediate notification for spills >1 bbl—all spills require notification to 

USCG, and BSEE 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;

• oversee spill source control and abatement operations by industry;

• sets requirements and reviews and approves oil-spill response plans (OSRP’s) for 

offshore facilities;

• conducts unannounced drills to ensure compliance with oil-spill response plans;

• requires operators to ensure that their spill-response operating and management 

teams receive appropriate spill-response training;

• conducts inspections of oil-spill response equipment;

• requires industry to show financial responsibility to respond to possible spills; and
3-20 Central Planning Area Lease Sales 235, 241, and 247 EIS

• provides research leadership to improve the capabilities for detecting and responding 

to an oil spill in the marine environment.

As indicated above, BSEE is now responsible for review and approval of OSRP’s. BOEM’s 

regulations require that an operator must have an approved OSRP prior to BOEM’s approval of an 

operator-submitted EP, DOCD, or production plan. 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.

This Agency also issued NTL’s and guidance documents that clarified additional oil-spill 

requirements after the Deepwater Horizon explosion, oil spill, and response occurred. The spill-responserelated NTL’s and guidance documents issued by BOEM and BSEE are described in detail in Chapter 

3.2.1.9 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. 

The NTL 2012-BSEE-N06, “Guidance to Owners and Offshore Facilities Seaward of the Coast Line 

Concerning Regional Oil Spill Response Plans,” was not discussed in the 2012-2017 WPA/CPA 

Multisale EIS since it was not effective until August 10, 2012. That NTL provides clarification, 

guidance, and information concerning the preparation and submittal of a regional OSRP for owners and 

operators of oil handling, storage, or transportation facilities, including pipelines located seaward of the 

coastline. The NTL also informs lessees, designated operators, or pipeline right-of-way holders, as 

appropriate, that they are responsible for preparing and submitting the OSRP. The BSEE’s Oil Spill 

Response Division will review all OSRP’s and approve those OSRP’s that are in compliance with 

30 CFR part 254. Some of the clarifications and encouraged practices in the NTL are based on lessons 

learned from the Deepwater Horizon explosion, oil spill, and response. Per the NTL, adherence to the 

encouraged practices will facilitate BSEE’s review of the OSRP’s, but adherence is not required to obtain 

approval. During BSEE’s review of regional OSRP’s, the Oil Spill Response Division will analyze the 

content of OSRP’s to ensure that the lessees demonstrate the ability to respond quickly and effectively 

whenever oil is discharged from a covered facility, as required by 30 CFR part 254. The NTL encourages 

lessees to specifically describe the planned response strategy for each worst-case discharge scenario 

included in the regional OSRP. The NTL indicates that the following factors should be considered when 

developing a response strategy:

• location of the potential worst-case discharge;

• proximity to sensitive resources;

• nature of the event;

• estimated discharge volume;

• oil characteristics;

• appropriate source control;

• containment methods;

• weathering (including natural dispersion); and

• other resources at risk.

There have been some changes to the spill-response equipment staging locations previously reported 

in the 2012-2017 WPA/CPA Multisale EIS. Due to these changes, it is expected that the oil-spill 

response equipment needed to respond to an offshore spill in the proposed CPA lease sale area could be 

called out from one or more of the following oil-spill equipment base locations: New Iberia, Belle Chase, 

Sulphur, Houma, Port Fourchon, Fort Jackson, Venice, Grand Isle, or Lake Charles, Louisiana; La Porte, 

Port Arthur, Aransas Pass, Ingleside, Galveston, or Houston, Texas; Pascagoula, Mississippi; Mobile, 

Alabama; or Pensacola, Panama City, Tampa, or Miami, Florida (USDOI, BSEE, 2013b).

In addition, the USCG has worked diligently to improve coastal oil-spill response since the 

Deepwater Horizon oil spill by replacing the One Gulf Plan with separate Area Contingency Plans 

(ACP’s) for each coastal USCG sector. The ACP’s cover subregional geographic areas and represent the 

third tier of the National Response Planning System mandated by the Oil Pollution Act of 1990. The 
Impact-Producing Factors and Scenario 3-21

ACP’s are a focal point of response planning. The Gulf of Mexico OCS Region’s ACP’s also include 

separate Geographic Response Plans, which are developed jointly with local, State, and other Federal 

entities to better focus spill response tactics and priorities. These Geographic Response Plans contain the 

resources initially identified for protection during a spill, response priorities, procedures, and appropriate 

spill-response countermeasures.

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, 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 pressure depending on the character of the oil (Owens 

et al., 2011).

3.2.2. Losses of Well Control

All losses of well control must be reported to BSEE. The BSEE clarified its procedure for loss of 

well control incident reporting in NTL 2010-N05, “Increased Safety Measures for Energy Development 

on the OCS,” effective June 8, 2010. The BSEE has also promulgated the Drilling Safety Rule (Federal 

Register, 2012a), effective October 22, 2012, which implements certain additional safety measures 

recommended in NTL 2010-N05 by incorporating the recommendations contained in the DOI report 

Increased Safety Measures for Energy Development on the Outer Continental Shelf (Safety Measures 

Report), dated May 27, 2010, and the Deepwater Horizon Joint Investigation Team report. The BSEE 

amended the drilling, well-completion, well-workover, and decommissioning regulations related to well 

control, including subsea and surface blowout preventers, well casing and cementing, secondary 

intervention, unplanned disconnects, recordkeeping, and well plugging. The Drilling Safety Rule also 

enhanced the description and classification of well-control barriers, defined testing requirements for 

cement, clarified requirements for the installation of dual mechanical barriers, and extended requirements 

for blowout preventers (BOP’s) and well-control fluids to well-completions, workovers, and 

decommissioning operations. Operators are required to document any loss of well-control event, even if 

temporary, and the cause of the event, and they are required to furnish that information by mail or email 

to the addressee indicated in the NTL. The operator does not have to provide information on kicks that 

were controlled, but the operator should include the release of fluids through a flow diverter (a conduit 

used to direct fluid flowing from a well away from the drilling rig).

The current definition for loss of well control is as follows:

• uncontrolled flow of formation or other fluids (the flow may be to an exposed 

formation [an underground blowout] or at the surface [a surface blowout]);

• uncontrolled flow through a diverter; and/or

• uncontrolled flow resulting from a failure of surface equipment or procedures.
3-22 Central Planning Area Lease Sales 235, 241, and 247 EIS

A loss of well control can occur during any phase of development, i.e., exploratory drilling, 

development drilling, well completion, production, or workover operations. A loss of well control can 

occur when improperly balanced well pressure results in sudden, uncontrolled releases of fluids from a 

wellhead or wellbore (PCCI Marine and Environmental Engineering, 1999; Neal Adams Firefighters, 

Inc., 1991). From 2006 to 2010, of the 27 loss of well-control events reported in the GOM, 7 (26%) 

resulted in loss of fluids at the surface or underground (USDOI, BSEE, 2012). In addition to spills, the 

loss of well control can resuspend and disperse bottom sediments. Historically, since 1971, most OCS 

blowouts have resulted in the release of gas, while blowouts resulting in the release of oil have been rare.

A BOP is a device with a complex of choke lines and hydraulic rams mounted atop a wellhead 

designed to close the wellbore with a sharp horizontal motion that may cut through or pinch shut casing 

and sever tool strings. The BOP’s were invented in the early 1920’s and have been instrumental in 

ending dangerous, costly, and environmentally damaging oil blowouts on land and in water. The BOP’s 

have been required for OCS oil and gas operations from the time offshore drilling began in the late 

1940’s.

The BOP’s are actuated as a last resort upon imminent threat to the integrity of the well or the surface 

rig. For a cased well, which is the typical well configuration, the hydraulic ram of a BOP may be closed 

if oil or gas from an underground zone enters the wellbore to destabilize the well. By closing a BOP, 

usually by redundant surface-operated and hydraulic actuators, the drilling crew can prevent explosive 

pressure release and allow control of the well to be regained by balancing the pressure exerted by a 

column of drilling mud with formation fluids or gases from below. Chapter 3.2.1.9.2 of the 2012-2017 

WPA/CPA Multisale EIS provides information on subsea well containment that could be utilized if a loss 

of well control occurred and resulted in a loss of fluids.

3.2.3. Pipeline Failures

The potential mechanisms for damage to OCS pipeline infrastructure include mass sediment 

movements and mudslides that can exhume or push the pipelines into another location, impacts from 

anchor drops or boat collisions, and accidental excavation or breaching because the exact whereabouts of 

a pipeline is uncertain. Pipeline failures could also be by rig/platform and pipeline activities supporting a 

CPA proposed action. Chapter 3.2.3 of the 2012-2017 WPA/CPA Multisale EIS describes previous 

incidents of OCS oil- and gas-related pipeline failures.

Any one of the mechanisms listed above could cause an OCS oil- and gas-related oil spill ≥1,000 bbl. 

Any resulting spill size would be limited by the size of the pipeline and the ability of an operator to 

quickly shut off flow from the source. The median spill size estimated from a pipeline failure is 2,200 bbl

(Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS). For a CPA proposed action, up to one spill of 

this size is estimated to occur during 40-year analysis period. 

3.2.4. Vessel Collisions

The BSEE revised operator incident reporting requirements in a final rule effective July 17, 2006 

(Federal Register, 2006). The new incident reporting rule more clearly defines what incidents must be 

reported, broadens the scope to include incidents that have the potential to be serious, and requires the 

reporting of standard information for both oral and written reports. As part of the incident reporting rule, 

BSEE’s regulations at 30 CFR § 250.188(a)(6) require an operator to report all collisions that result in 

property or equipment damage greater than $25,000. “Collision” is defined as the act of a moving vessel 

(including an aircraft) striking another vessel or striking a stationary vessel or object (e.g., a boat striking 

a drilling rig or platform). Chapter 3.2.4 of the 2012-2017 WPA/CPA Multisale EIS provides data related 

to vessel collisions and discusses methods of prevention and avoidance of vessel collisions. No new data 

have emerged that would cause BSEE to reevaluate its analysis for this Supplemental EIS.

3.2.5. Chemical and Drilling-Fluid Spills

Chapter 3.2.5 of the 2012-2017 WPA/CPA Multisale EIS describes OCS oil- and gas-related 

chemical and synthetic-based fluid spills. Below is a brief summary of that information.

Chemicals are stored and used to condition drill muds during production and in well completions,

stimulation, and workover procedures. The most common chemicals spilled are methanol, ethylene 
Impact-Producing Factors and Scenario 3-23

glycol, and zinc bromide. Methanol and ethylene glycol may be used as a treatment to prevent the 

formation of gas hydrates while zinc bromide may be used in completion fluids. The chemicals that are 

used the most are also the chemicals that are spilled in the greatest volume. Completion fluids are used in 

the largest quantity and constitute the largest volume of accidental releases. Completion fluids consist of 

brines made from seawater mixed with calcium chloride, calcium bromide, and/or zinc bromide. A study 

of chemical spills from OCS activities determined that only two chemicals could potentially impact the 

marine environment—zinc bromide and ammonium chloride (Boehm et al., 2001). Both of these 

chemicals are used for well treatment or completion and, therefore, are not in continuous use. Most other 

chemicals are either nontoxic or used in small quantities. There are some differences in the operational 

needs for chemicals in deepwater versus shallow-water operations. Higher volumes of treatment 

chemicals (e.g., defoamers and hydrate inhibitors) are used in deepwater environments due to the 

conditions encountered there (Boehm et al., 2001).

Synthetic-based fluids (SBF’s) or synthetic-based muds (SBM’s) have been used since the mid 

1990’s. In deepwater drilling, SBF’s are preferred over water-based muds because of the SBF’s superior 

performance properties. The synthetic oils used in SBF’s are relatively nontoxic to the marine 

environment and have the potential to biodegrade. However, it should be noted that SBF’s are not 

permitted to be discharged into the marine environment; only cuttings wetted with SBF may be 

discharged after the majority of synthetic fluid has been removed. For further discussion on this topic, 

refer to Chapter 3.1.1.4.1 of the 2012-2017 WPA/CPA Multisale EIS. Accidental riser disconnects could 

result in the release of large quantities of drilling fluids and are of particular concern when SBF’s are in 

use.

The BSEE tracks spill incidents of ≥1 bbl in size of chemical and synthetic-based fluids resulting 

from OCS oil and gas activities, and has historically produced counts and summaries for spills ≥50 bbl.. 

Table 3-8 provides information related to the number and volume of chemical and synthetic-based fluid 

spills in the GOM based on BSEE’s counts and summaries. These data have been updated since the WPA 

233/CPA 231 Supplemental EIS, which covered spills during the period of 2002-2009. A summary of 

2013 data is not yet available. However, BOEM has conducted a search of the National Response Center 

database for standard reports using the search criteria “drilling mud” under the database’s “material” 

field. This search revealed one spill of ≥1,000 bbl, which was a spill of 1,531 bbl in April 2013 due to an 

unplanned riser disconnect (U.S. Dept. of Homeland Security, CG, 2013). Despite this spill, the updated 

chemical and SBF spills remain within the range of data presented in the 2012-2017 WPA/CPA Multisale 

EIS (Table 3-27) and WPA 233/CPA 231 Supplemental EIS. Thus, this new information did not change 

the validity of the chemical and SBF spills previously presented. 

3.3. CUMULATIVE ACTIVITIES SCENARIO

3.3.1. OCS Program

The OCS Program scenario includes all activities that are projected to occur from past, proposed, and 

future lease sales during the 40-year analysis period. Projected reserve/resource production for the OCS 

Program (Table 3-1; WPA, CPA, and EPA) is 18.34-25.64 BBO and 75.886-111.627 Tcf of gas. Table 

3-3 of this Supplemental EIS presents projections of the major activities and impact-producing factors 

related to future Gulf of Mexico OCS Program activities. 

The level of OCS activity is connected to oil prices, resource potential, cost of development, and rig 

availability rather than just, or even primarily to, the amount of acreage leased. The impacts of activities 

associated with the OCS Program on biological, physical, and socioeconomic resources are analyzed in 

the cumulative impacts analysis sections of Chapter 4.1 of this Supplemental EIS and Chapters 4.1.1 and 

4.2.1 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 233 Supplemental EIS. 

Note that offshore and onshore impact-producing factors and scenarios associated with a WPA or an 

EPA proposed action (i.e., a typical lease sale that would result from a proposed action within the WPA

or EPA) as well as OCS Program activity resulting from past and future lease sales in the WPA or EPA, 

are disclosed in the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and EPA 225/226 EIS.
3-24 Central Planning Area Lease Sales 235, 241, and 247 EIS

3.3.2. State Oil and Gas Activity

All five Gulf Coast States have had some historical oil and gas exploration activity and, with the 

exception of Florida and Mississippi, currently produce oil and gas in State waters. The coastal 

infrastructure that supports the OCS Program also supports State oil and gas activities.

State oil and gas infrastructure consists of the wells that extract hydrocarbon resources, facilities that 

produce and treat the raw product, pipelines that transport the product to refineries and gas facilities for 

further processing, and additional pipelines that transport finished product to points of storage and final 

consumption. The type and size of infrastructure that supports production depends upon the size, type, 

and location of the producing field, the time of development, and the life cycle stage of operations. 

Chapter 3.3.2 of the 2012-2017 WPA/CPA Multisale EIS provides a reference for relevant historical 

information on State leasing programs. The most recent lease sale information for Texas and Louisiana 

has been updated below.

Texas 

The most recent oil and gas lease sale occurred on January 7, 2013. Ninety-two parcels containing 

more than 27,432 ac of State lands were offered for oil and gas leasing in the offshore area by Texas State 

University Lands (State of Texas, General Lands Office, 2014). BOEM expects that Texas will conduct 

regular oil and gas lease sales during the 40-year cumulative activities scenario for OCS activity, although 

the lease sale’s regularity could differ from current practices.

Louisiana

The most recent oil and gas lease sale occurred on January 9, 2014. Twenty-four leases containing 

more than 35,633 ac were offered for oil and gas leasing by the Office of Mineral Resources on the behalf 

of the State Mineral Board for Louisiana. The January 9, 2014, State lease sale awarded two leases for 

eight offered offshore areas, with a total acreage of 500 ac. During the 2012-2013 Fiscal Year, 

45 offshore leases containing more than 83,187 ac were offered; of these, only 13 leases were awarded. 

BOEM expects that Louisiana will conduct regular oil and gas lease sales during the 40-year cumulative 

activities scenario for OCS activity, although the lease sale’s regularity could differ from current practices 

(State of Louisiana, Dept. of Natural Resources, 2014).

Mississippi

BOEM expects Mississippi to institute a lease sale program in the near future and to begin leasing in 

State waters during the 40-year cumulative activities scenario for OCS activity analyzed in this 

Supplemental EIS. 

Alabama 

Alabama has no established schedule of lease sales. The limited number of blocks in State waters has 

resulted in the State not holding regularly scheduled lease sales. The last lease sale was held in 1997. 

BOEM does not expect Alabama to institute a lease sale program in the near future, although there is at 

least a possibility of a lease sale in State waters during the 40-year cumulative activities scenario for OCS 

activity following a CPA proposed action.

Florida

Gulf Oil drilled the first offshore exploration wells in Florida in 1947; these wells were in Florida Bay 

south of Cape Sable in Monroe County. In 1956, Humble Oil drilled an exploration well in the State 

waters of Pensacola Bay in Santa Rosa County. All wells drilled in State waters were dry holes. Florida 

banned drilling in State waters in 1992. In 2005, Florida’s Governor Jeb Bush and the Florida Cabinet 

signed a historic settlement agreement to buy out any existing leases in State waters and to eliminate the

potential for oil drilling there. Between 1987 and 1995, Chevron made commercial gas discoveries in the 

Destin Dome leasing area, which is 25 mi (40 km) south of the western end of the Florida Panhandle in 

Federal OCS waters. The State of Florida objected to plans to produce the discovery. In May 2002, the 
Impact-Producing Factors and Scenario 3-25

U.S. Government agreed to buy back seven leases from Chevron, Conoco, and Murphy Oil for 

$115 million and to hold in abeyance any further development of the Destin Dome discovery until 2012. 

The enactment of the Gulf of Mexico Energy Security Act extended the abeyance of the development of 

the Destin Dome discovery until 2022 and areas within 100 mi (161 km) of the coastline of the State of 

Florida.

In April 2009, three committees of the Florida House of Representatives approved a bill that would 

allow offshore drilling in State waters >3 mi (4.8 km) from the eastern Gulf shore. The bill passed the 

Florida House in April 2009 but died soon after in the Florida Senate.

BOEM does not expect Florida to institute a lease sale program in the near future, although it is 

possible that a change in policy could lead to leasing on the OCS or in State waters during the 40-year 

cumulative activities scenario for OCS activity analyzed in this Supplemental EIS.

Pipeline Infrastructure

A mature pipeline network exists in the GOM to transport oil and gas production from the OCS to 

shore (Chapter 4.1.1.23.1). The network carries oil and gas onshore and inland to refineries and 

terminals, and a network of pipelines distributes finished products such as diesel fuel or gasoline to and 

between refineries and processing facilities onshore (Peele et al., 2002, Figure 4.1). Expansion of this 

network is projected to be primarily small-diameter pipelines to increase the interconnectivity of the 

existing network and a few major interstate pipeline expansions. Any new larger-diameter pipelines 

would likely be constructed to support onshore and offshore LNG terminals. Refer to Chapter 3.3.2 of the 

2012-2017 WPA/CPA Multisale EIS for information on pipeline infrastructure activities within the State 

waters of Texas, Louisiana, Mississippi, and Alabama.

3.3.3. Other Major Factors Influencing Offshore Environments

Other influencing factors occur concurrently with OCS activity in the offshore areas of the Gulf Coast 

States. Some of these factors are (1) dredged material disposal, (2) OCS sand borrowing, (3) marine 

transportation, (4) military activities, (5) artificial reefs and rigs-to-reefs development, (6) offshore LNG 

projects, (7) development of gas hydrates, and (8) renewable energy and alternative use.

Cumulative impacts to biological, physical, and socioeconomic resources from these types of nonOCS activities are analyzed in the cumulative impacts analysis sections in Chapter 4.1 of this 

Supplemental EIS and in Chapters 4.1.1 and 4.2.1 of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. 

3.3.3.1. 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 banks and in ocean dredged-material disposal sites 

(ODMDS’s), which are regulated by USEPA under the Clean Water Act and the Marine Protection, 

Research, and Sanctuaries Act. 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.

If funds are available, COE uses dredge materials beneficially for restoring and creating habitat, for 

beach nourishment projects, and for industrial and commercial development (Chapter 3.3.4.3). 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 small authorized open-water disposal areas in Louisiana and Mississippi along open-water stretches 

of the main Gulf Intracoastal Waterway (GIWW) between Louisiana and Mississippi: Louisiana Disposal 

Area 66 (1,593 ac; 645 ha); and Mississippi Disposal Area 65A (1,962 ac; 794 ha), Disposal Area 65B 

(815 ac; 330 ha), and Disposal Area 65C (176 ac; 71 ha) (U.S. Dept. of the Army, COE, 2010, Table 5). 

Dredged materials from the GIWW are sidecast at these locations. The ODMDS’s utilized by COE in the 

cumulative activities area include those shown in Table 3-30 of the 2012-2017 WPA/CPA Multisale EIS. 

Maps on the USEPA’s website show the locations for the ODMDS’s in Louisiana and Texas (USEPA, 

2011). 
3-26 Central Planning Area Lease Sales 235, 241, and 247 EIS

There are two primary Federal environmental statutes governing dredge material disposal. The 

Marine Protection, Research, and Sanctuaries Act (also called the Ocean Dumping Act) governs 

transportation of dredge material 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) COE issues permits under the Clean Water Act and the Marine 

Protection, Research, and Sanctuaries Act; (2) 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) USEPA is responsible for identifying 

recommended ODMDS’s. 

The COE’s Ocean Disposal Database reports the amount of dredged material disposed in ODMDS’s 

by district (U.S. Dept. of the Army, COE, 2010). Table 3-9 shows the quantities of dredged materials 

disposed of in ODMDS’s between 2001 and 2010 by the COE’s Galveston and New Orleans Districts.

The New Orleans District dredges an average annual 78 million yd3 (59,635,279 m3

). Current figures 

estimate that approximately 38 percent (or 30 million yd3 [22,936,646 m3

]) 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 COE’s New Orleans District is disposed of at 

placement areas regulated under Section 404 of the Clean Water Act, at ODMDS’s, or it 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).

Cumulative Activities Scenario: BOEM anticipates that over the next 40 years the amount of dredged 

material disposed at ODMDS’s will fluctuate but that it will generally follow historical trends of the 

practice utilized to date by the Galveston and New Orleans Districts. Over the last 10 years, the 

Galveston District has averaged about 6.9 million yd3 (5.3 million m3

) of material dredged per year 

disposed at ODMDS’s, while the New Orleans District has averaged about 21.7 million yd3

(16.6 million m3

) of material dredged per year disposed at ODMDS’s. Quantities may decrease slightly 

as various entities identify additional onshore sites for the beneficial uses of dredged material. The 1972 

Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (the London 

Convention), to which the U.S. is a signatory, requires annual reporting of the amount of materials 

disposed at sea. The COE prepares the dredged material disposed portion of the report to the 

International Maritime Organization; these yearly reports are available on the COE’s Ocean Disposal 

Database (U.S. Dept. of the Army, COE, 2010b).

3.3.3.2. 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 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 

38 noncompetitive negotiated agreements, but it has never had a competitive lease sale for OCS sand and 

gravel resources. The OCS Program continues to focus on identifying sand resources for coastal 

restoration, investigating the environmental implications of using those resources, and processing 

noncompetitive use requests.

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 near-offshore OCS of 

Louisiana, an area where competitive space use mainly involves OCS oil and gas infrastructure such as 

wells, platforms, and pipelines. Table 3-32 of the 2012-2017 WPA/CPA Multisale EIS 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 Marine Minerals Program. To visualize such a dimension, this 

volume of sand could fill the Louisiana Superdome stadium 16.5 times.

BOEM received earmarked funds in 2005 to conduct offshore sand studies to investigate available 

sources of OCS sand for restoring coastal areas in Louisiana, Texas, Alabama, and Mississippi that were 

damaged by Hurricanes Katrina and Rita. Sand sources identified through this Agency’s cooperative 

effort with Louisiana will likely serve as the major source of material for the restoration of the barrier 

islands planned as part of the Louisiana Coastal Area ecosystem restoration study (U.S. Dept. of the 
Impact-Producing Factors and Scenario 3-27

Army, COE, 2004), projects identified in the Louisiana 2012 Coastal Master Plan (State of Louisiana, 

Coastal Protection and Restoration Authority, 2012a), and projects developed under the Deepwater

Horizon NRDA and 2012 Resources and Ecosystems Sustainability, Tourist Opportunities and Revived 

Economies of the Gulf Coast States Act (RESTORE Act) barrier island restoration efforts. The Louisiana

Coastal Protection and Restoration Authority and Louisiana State University have undertaken joint 

efforts, funded in part through BOEM, to identify potential sand resources in the Trinity and Tiger Shoal 

complex, located in the Vermilion and South Marsh Island leasing areas, and to examine the long-term 

effects of dredging sand on Ship Shoal, a large potential borrow area about 15 mi (24 km) offshore Isle 

Dernieres, south-central Louisiana. BOEM also has a cooperative agreement with the Louisiana 

Geological Survey to conduct an evaluation of sand resources associated with paleochannels offshore 

Cameron Parish, Louisiana. Meanwhile, the General Lands Office in Texas has collected new geologic 

and geophysical data to describe potential resources in buried Pleistocene Sabine and Colorado River 

paleochannels, located offshore Jefferson and Brazoria Counties.

Since the dredging of OCS sand and the associated activities of oceangoing dredge vessels could 

present some use conflicts on blocks also leased for oil and/gas extraction, 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.

No sand leases have ever been issued for OCS sand in the WPA. The following seven leases for OCS 

sand have been issued in the CPA: (1) Holly Beach, Cameron Parish, Louisiana; (2) the South Pelto test 

area, Terrebonne Parish, Louisiana; (3) Pelican Island shoreline restoration, Plaquemines Parish, 

Louisiana; (4) Raccoon Island marsh creation, Terrebonne Parish, Louisiana; (5) St. Bernard Shoals, 

St. Bernard and Plaquemines Parishes, Louisiana; (6) Ship Shoal in South Pelto Area for Caminada 

Headland restoration in Lafourche and Jefferson Parishes, Louisiana; and (7) Sabine Bank in West 

Cameron Area for Cameron Parish shoreline restoration, Cameron Parish, Louisiana. Dredging for the 

Caminada Headland and Cameron Parish Restoration Projects in South Pelto and West Cameron Areas, 

respectively, began in August 2013 and is expected to continue through the summer of 2014.

In early 2014, BOEM is expected to issue two new leases in Louisiana: the first is for the Deepwater

Horizon NRDA Whiskey Island Restoration Project in Terrebonne Parish using sand from Ship Shoal 

Block 88; and the second is for Phase Two of the Caminada Headland Restoration Project in Lafourche 

and Jefferson Parishes using sand from South Pelto Blocks 13 and 14. BOEM anticipates that dredging 

for these projects will begin in late 2014. BOEM is also working with the COE’s Mobile District and the 

National Park Service on the Mississippi Coastal Improvements Program, which will use OCS sand from 

the Mobile Area for barrier island restoration projects along East and West Ship Islands in the Gulf Island 

National Seashore. Dredging associated with the Mississippi Coastal Improvements Program will likely 

begin in late 2014. In July 2013, BOEM began working with NOAA and FWS on a North Breton Island 

Restoration Project planning proposal that will be included in the forthcoming draft NRDA restoration 

plan. The North Breton Island Restoration Project (Louisiana) will use sand from the Breton Sound Area 

to restore shorebird and brown pelican nesting habitat in the Breton National Wildlife Refuge. The U.S. 

Geological Survey will be conducting sand resource surveys in summer 2014, and it is estimated that 

dredging for the North Breton Island Restoration Project will begin in late 2015.

BOEM has outlined its responsibility as steward of significant sand resources on the OCS in NTL 

2009-G04. That NTL provides guidance for the avoidance and protection of significant OCS sediment 

resources essential to coastal restoration initiatives in the BOEM Gulf of Mexico OCS Region.

Cumulative Activities Scenario: Over the next 40 years, increased use of OCS sand for Louisiana 

restoration projects is likely. Currently, no Texas restoration projects have been specifically identified. 

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 Lands Office, in 

cooperation with BOEM and the Texas Bureau of Economic Geology, has investigated the potential for 

use of Heald and Sabine Banks as borrow for beach restoration projects, but it has yet to identify specific 

projects. With respect to Louisiana, some uncertainty exists as to the amount of offshore OCS sand that 

will eventually be sought for coastal restoration projects. The Louisiana Coastal Area Ecosystem 
3-28 Central Planning Area Lease Sales 235, 241, and 247 EIS

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 will 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, the Deepwater Horizon NRDA restoration, and the Gulf of 

Mexico Energy Security Act.

3.3.3.3. 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 2011, the Port of Houston was the second largest port in the United States, 

while the Port of New Orleans was the sixth largest. Tankers carrying mostly petrochemicals account for 

about 60 percent of the vessel calls in the Gulf of Mexico. Dry-bulk vessels including bulk vessels, bulk

containerships, cement carriers, ore carriers, and wood-chip carriers accounted for another 17 percent of 

the vessel calls. The GOM also supports a popular cruise industry. In 2011, there were 149 cruise ship 

departures from Galveston, 139 cruise ship departures from New Orleans, and 199 cruise ship departures 

from Tampa (USDOT, MARAD, 2012). 

Total port calls, or vessel stops at a port, in the U.S. are increasing as a whole, and total port calls 

within the GOM are also increasing. Gulf of Mexico port calls represent approximately 32 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 over the last decade, from 17,673 in 2002 to 22,989 in 2011

(USDOT, MARAD, 2013a) (Table 3-10). 

Table 3-2 presents the estimated number of vessel trips that would occur as a result of a CPA 

proposed action. Annual OCS oil- and gas-related vessel traffic due to a CPA proposed action represents 

a small proportion (<1%) of the total vessel traffic in the GOM (Chapter 3.1.1.8 of this Supplemental 

EIS and Chapter 3.1.1.8.4 of the 2012-2017 WPA/CPA Multisale EIS). Annual OCS oil- and gas-related 

vessel traffic due to cumulative OCS activity represents between 9 and 12 percent of the total traffic in the 

GOM.

Cumulative Activities Scenario: It is expected that the usage of GOM ports will continue to increase 

by approximately 3 percent annually over the next 40 years. As such, it is anticipated that port calls by all 

ship types will be bounded annually by a lower limit of current use and an upper limit of approximately 

85,000 vessel port calls.

3.3.3.4. Military Activities

Twelve military warning areas and six Eglin Water Test Areas are located within the Gulf (Figure 

2-2). Six designated military areas and three Eglin Water Test Areas (EWTA’s) that are used for military 

operations lie wholly or partially within the CPA (Figure 2-2). The military warning areas within the 

CPA total approximately 13.3 million ac (about 23% of the total acreage of the CPA). The EWTA’s 

within the CPA total approximately 7 million ac (about 12% of the total acreage of the CPA). Chapter 

3.3.3.4 of the 2012-2017 WPA/CPA Multisale EIS describes military activities within the OCS.

Cumulative Activities Scenario: BOEM anticipates that, over the next 40 years, the military use areas 

currently designated in the CPA will remain the same and that none of them would be released for 

nonmilitary use. Over the cumulative activities scenario, BOEM expects to continue to require military 

coordination stipulations in these areas. The intensity of the military’s use of these areas, or the type of 

activities conducted in them, is anticipated to fluctuate with the military mission needs.

3.3.3.5. Artificial Reefs and Rigs-to-Reefs Development

Artificial reefs have been used along the coastline of the U.S. since the early 19th century. Stone 

(1974) documented that the use of obsolete materials to create artificial reefs has provided valuable 

habitat for numerous species of fish in areas devoid of natural hard bottom. Stone et al. (1979) found 

reefs in marine waters not only attract fish but, in some instances, also enhance the production of fish. All 

of the five Gulf Coast States—Texas, Louisiana, Mississippi, Alabama, and Florida—have artificial reef 

programs and plans.
Impact-Producing Factors and Scenario 3-29

Most OCS platforms have the potential to serve as artificial reefs. Offshore oil and gas platforms 

began providing artificial reef substrate in the GOM with the first platform’s installation in 1942. 

Currently, approximately 12 percent of the platforms decommissioned in the Gulf OCS have been used in 

the Rigs-to-Reefs Program. It is anticipated that approximately 10 percent of platforms installed as a 

result of a WPA or CPA proposed action would be converted to a reef after decommissioning. This factor 

is prompting increased public attention on the ecologic value of oil and gas structures for their reef 

effects. Ongoing studies aim at evaluating the ecology of offshore structures and may lead to a greater 

emphasis on the creation of artificial reefs through the Rigs-to-Reefs Program. At present, Texas, 

Louisiana, and Mississippi participate in the Rigs-to-Reefs Program.

CPA Proposed Actions Scenario (Typical Lease Sale): The number of platform removals projected 

for a CPA proposed action is 35-67 (Table 3-2 of this Supplemental EIS and Table 3-3 of the 2012-2017 

WPA/CPA Multisale EIS). The number of rigs anticipated to enter the Rigs-to-Reefs Program as a result 

of a CPA proposed action is approximately 10 percent of the projected removals, or 3-7 in the CPA.

OCS Program Scenario: Over the course of the 40-year cumulative activities scenario for the OCS 

Program (2012-2051), BOEM projects that a total of 1,279-1,837 platforms will be removed (Table 3-3). 

If approximately 10 percent of these structures are accepted into the Rigs-to-Reefs Program, there may be 

as many as 128-184 additional artificial reefs installed in the WPA, CPA, and EPA. Note that offshore 

and onshore impact-producing factors and scenarios associated with a WPA or an EPA proposed action 

(i.e., a typical lease sale that would result from a proposed action within the WPA or EPA) as well as 

OCS Program activity resulting from past and future lease sales in the WPA or EPA, are disclosed in the 

2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and EPA 225/226 EIS.

3.3.3.6. Offshore Liquefied Natural Gas Projects and Deepwater Ports

There are currently no LNG terminals operating on the OCS in the GOM. The following provides 

updates to the status of LNG projects and deepwater ports in the GOM as provided in Chapter 3.3.3.6 of 

the 2012-2017 WPA/CPA Multisale EIS.

Louisiana

Gulf Gateway Energy Bridge. On February 22, 2012, Excelerate Energy notified the U.S. 

Department of Transportation’s Maritime Administration (MARAD) and the USCG of its intention to 

decommission the Gulf Gateway Energy Bridge deepwater port, the only operational LNG terminal 

operation on the OCS in the GOM. Excelerate’s decision to decommission the facility was due to 

irreparable hurricane damage to pipelines interconnecting with the deepwater port and a changing natural 

gas market, which impacted the operator’s ability to receive consistent shipments. After careful review 

and evaluation of the proposed removal plans, MARAD and other Federal agencies authorized 

Excelerate’s decommissioning program for the Gulf Gateway Energy Bridge deepwater port (USDOT, 

MARAD, 2013b). 

Main Pass Energy Hub. Due to significant financial challenges over the past several years, Freeport 

McMoRan was unable to comply with the conditions of the Record of Decision. As such, on January 2, 

2012, MARAD moved forward to rescind approval of the Record of Decision for the Freeport McMoRan 

project (USDOT, MARAD, 2013b). 

Texas 

Texas Offshore Port System. On April 12, 2010, the applicant submitted a letter to MARAD to 

withdraw its application due to its inability to secure necessary financing. The MARAD, in a letter dated 

May 5, 2010, acknowledged Texas Offshore Port System’s withdrawal and, thereafter, terminated the 

application and all processing activities. This project remains closed with MARAD (USDOT, MARAD, 

2013c). 

Florida

Port Dolphin. On March 29, 2007, Port Dolphin Energy LLC filed an application with MARAD to 

construct a deepwater port located in Federal waters approximately 28 mi (45 km) offshore of Tampa, 
3-30 Central Planning Area Lease Sales 235, 241, and 247 EIS

Florida. The applicant is a wholly-owned subsidiary of Höegh LNG. The proposed port will consist of 

two submerged turret loading buoys similar to those used in the Northeast Gateway and Neptune projects. 

On October 26, 2009, MARAD issued a Record of Decision approving, with conditions, the Port Dolphin 

Energy Deepwater Port License application, and on April 19, 2010, the official license was issued. Port 

Dolphin is currently working with the relevant Federal and State of Florida agencies to obtain the required 

authorizations and permits for construction and operation of the facility. Construction of the Port Dolphin 

facility commenced in late 2013 (USDOT, MARAD, 2013b).

3.3.3.7. Development of Gas Hydrates

Gas hydrates are a unique, energy-rich, and poorly understood class of chemical substances in which 

molecules of one material (in this case solid-state water ─ ice) form an open lattice that physically 

encloses molecules of a certain size (in this case ─ methane) in a cage-like structure without chemical 

bonding (Berecz and Balla-Achs, 1983; Henriet and Mienert, 1998; Collett, 2002). The DOE and 

cooperating agencies have conducted a multiyear characterization program of naturally occurring 

methane hydrates (gas hydrates) in the GOM. The first cruise for characterizing GOM gas hydrates took 

place in 2005, and the second took place in 2009. The following provides an update to the Joint Industry 

Project (JIP) information in Chapter 3.3.3.7 of the 2012-2017 WPA/CPA Multisale EIS.

Following the events of the Deepwater Horizon incident in the Gulf of Mexico, the 

conditions and requirements for drilling operations in the Gulf of Mexico underwent a 

dramatic change that resulted in a substantial and detailed evaluation of what is plausible 

(and affordable) during the remainder of the project. As a result of this evaluation, the 

JIP and DOE have determined to focus the remainder of the project on the development 

and testing of an integrated suite of pressure coring and pressure core handling and 

analysis devices in collaboration with research and development experts from 

government, academia, and industry. The coring tools will have the flexibility to be used 

from various platforms in future DOE marine hydrate research expeditions. A decision 

has been made that a Leg III drilling / pressure coring expedition will not be conducted as 

part of this project (USDOE, National Energy Technology Laboratory, 2013a). 

Methodologies for the extraction and production of gas hydrates are being developed in a 

collaborative field trial between ConocoPhillips-Japan Oil, Gas, and Metals National Corporation and 

DOE at the Iġnik Sikumi well site in Alaska. The Iġnik Sikumi gas hydrate test well was drilled and 

logged during the winter of 2010/2011, and gas hydrate production testing was carried out there during 

the winter of 2011/2012. A production method was tested by injecting a combination of carbon dioxide 

and nitrogen gas into the methane hydrate reservoir. The injection phase was followed by an extended 

period of depressurization and flowback of gas (including methane) to the surface. The data from this 

study are still being analyzed, but the effort represents the first extraction of methane gas (USDOE, 

National Energy Technology Laboratory, 2013b). A multiyear project is also being led by the Japan Oil, 

Gas, and Metals National Corporation and Japan’s National Institute of Advanced Industrial Science and 

Technology and in collaboration with the U.S. Geological Survey’s Gas Hydrates Project, researchers 

from Georgia Tech, DOE, and the JIP in Japan. In 2012, researchers retrieved and preserved pressurized 

sediment cores containing gas hydrates from the Nankai Trough offshore Japan. These researchers are 

also conducting the first offshore production test to track how much methane can be released from 

deepwater gas hydrate deposits (USDOI, GS, 2013). The development of offshore production methods is 

essential to gas hydrate production methods in the Gulf of Mexico.

This does not change BOEM’s anticipation that, within 40 years, it is likely that the first U.S. 

domestic production from gas hydrates may occur in Alaska, where gas obtained from onshore hydrates 

will either support local oil and gas field operations or be available for commercial sale if and when a gas 

pipeline is constructed to the lower 48 states. However, Moridis et al. (2008) stated that it is not possible 

to discount the possibility that the first U.S. domestic production of gas hydrates could occur in the GOM. 

Despite the substantially increased complexity and cost of offshore operations, there is a mature network 

of available pipeline capacity and easier access to markets in the Gulf of Mexico. 
Impact-Producing Factors and Scenario 3-31

3.3.3.8. Renewable Energy and Alternative Use

The two primary categories of renewable energy that have the potential for development in the coastal 

and OCS waters of the U.S. are (1) wind turbines and (2) marine hydrokinetic systems. Chapter 3.3.3.8 

of the 2012-2017 WPA/CPA Multisale EIS describes renewable energy and alternative use programs and 

potential action within the OCS.

3.3.4. Other Major Factors Influencing Coastal Environments

The GOM is a dynamic, constantly changing system where natural and human-caused factors 

simultaneously impact both the coastal areas of the Gulf Coast States and OCS activities. These factors 

include (1) sea-level rise and subsidence, (2) Mississippi Delta hydromodification, (3) maintenance 

dredging and Federal channels, and (4) coastal restoration programs.

Cumulative impacts to biological, physical, and socioeconomic resources from these types of nonOCS activities are analyzed in the cumulative impacts analysis sections of Chapter 4.1 of this 

Supplemental EIS and Chapters 4.1.1 and 4.2.1 of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. 

3.3.4.1. 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): absolute sea-level rise and relative sealevel rise. Absolute sea-level rise refers to a net increase in the volume of water in the world’s oceans. 

Relative sea-level rise refers to the appearance of sea-level rise, a circumstance where subsidence of the 

land is taking place at the same time that an absolute sea-level change may be occurring. Geologists tend 

to consider all sea-level rise as relative because the influence of one or the other is difficult to separate 

over geologic 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 to modeled 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 sea-level rise rate increased from the 19th to the 20th century. 

The average global rate for the 20th century was determined by Bindoff et al. (2007) to be 1.7 ± 0.5 mm/yr 

(0.066 ± 0.02 in) and the total 20th-century average rise is estimated to be 0.17 m (0.55 ft) (Bindoff et al. 

2007). 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.
3-32 Central Planning Area Lease Sales 235, 241, and 247 EIS

Although absolute sea-level rise is a contributor to the total amount of sea-level rise along the Gulf 

Coast, subsidence is the most important contributor to the total. In comparison to other areas along the 

Gulf Coast, Louisiana’s Mississippi Delta and Chenier Plains are built of young sediments deposited over 

the last 7,000 years. These deltaic sediments have been undergoing compaction and subsidence since 

they were deposited. The land is sinking at the same time that sea level is rising, contributing to high 

rates of relative sea-level rise along the Louisiana coast. Blum and Roberts (2009) posited 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 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 LCA, 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. It 

is an oversimplification of a complex system when applied to the entire coast, but it is an estimate that is 

reasonable based on recent data.

Stephens (2009 and 2010a) reported that the influence of subsurface structure has not been taken into 

account in subsidence assessments in the LCA and along the Gulf Coast (Stephens, 2009, 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

(~9.6 mm/yr; 0.38 in/yr) in the United States (Pendleton et al., 2010). 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 very low vulnerability category still have some 

sea-level rise (1.38 mm/yr [0.054 in/yr] at Apalachicola, Florida). Given this range, BOEM anticipates 

that, over the next 40 years, the northern GOM will likely experience a minimum relative sea-level rise of 

55.2 mm (2.17 in) and a maximum relative sea-level rise of 384 mm (15.1 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 could 

potentially be affected by sea-level rise during this program. Refer to Chapter 4.1.1.23.1 for sea-level 

rise effects to land use and infrastructure associated with the OCS Program. Programmatic aspects of 

climate change relative to the environmental baseline for the Gulf of Mexico OCS Program are discussed 

in Appendix G.3 of the 2012-2017 WPA/CPA Multisale EIS.

Formation Extraction and Subsidence

Extracting fluids and gas from geologic formations can lead to localized subsidence at the surface. 

The Texas Gulf of Mexico coast is experiencing high (5-11 mm/yr; 0.19-0.43 in/yr) rates of relative sealevel rise that are the sum of subsidence and eustatic (absolute) sea-level rise (Sharp and Hill, 1995). 

Even higher rates are associated with areas of groundwater pumping from confined aquifers. Berman 

(2005, 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) shows measured subsidence 

along transects across these fields that range from 4 to 18 mm/yr (0.15 to 0.7 in/yr), 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 is consistent with theoretically expected reservoir compaction; 

however, they could not explain the entirety of localized rates to the subsidence rates measured and 

observed on a regional scale.

Dokka (2011) suggests that the magnitude of deep subsidence in urban New Orleans, an area that has 

limited oil and gas production, is too large to be explained by any combination of faulting, deep 
Impact-Producing Factors and Scenario 3-33

compaction, and lithospheric loading alone. Dokka proposes that the residual subsidence is caused 

largely due to local and regional groundwater withdrawal, causing as much as 0.8 m (2.6 ft) of subsidence 

since around 1960.

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 million 

cubic feet (MMcf) in 1969 (Ko and Day, 2004). 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) and Ko and Day 

(2004) 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.

3.3.4.2. 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 allowed for the 

river to flood and distribute alluvial sediments across the delta platform and for 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 canals 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 (2009) 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 required to build and maintain the modern delta plain, a figure 

largely in agreement with previous work reporting decreases in suspended sediment load of nearly 

60 percent since the 1950’s (Turner and Cahoon, 1987, Figure 3-8; Tuttle and Combe, 1981).

Blum and Roberts (2009) posited four scenarios for subsidence and sea-level rise, and 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 contributing to landloss. The use of sediment 

budget modeling, a relatively new tool for landloss assessment, appears to indicate that hydrographic 

modification of the Mississippi River has been the most profound man-caused influence on landloss in the 

LCA. Sediment starvation of the deltaic system is allowing rising sea level and subsidence to outpace the 

constructive processes building and maintaining the delta.

BOEM anticipates that, over the next 40 years, there might be minor sediment additions resulting 

from new and continuing freshwater diversion projects managed by COE. Of the 196 projects in the 1990 

Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) program (LaCoast.gov, 2013), 

8 involve the introduction of sediment or the reestablishment of natural water and sediment flow regimes 

to allow the delta plain to replenish and build up, 9 are freshwater diversion projects, 8 are outfall 

management, 3 are sediment diversion, and 49 are marsh creations. Insofar as these projects represent 
3-34 Central Planning Area Lease Sales 235, 241, and 247 EIS

land additions to the LCA, they are already accounted for in the discussion below under coastal 

restoration programs.

3.3.4.3. Maintenance Dredging and Federal Channels

Along the Texas Gulf Coast there are eight federally maintained navigation channels in addition to 

the 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).

Maintenance dredging activity from 2001 through 2010 for Federal channels by COE’s Galveston 

District are reported in COE’s Ocean Disposal Database (U.S. Dept. of the Army, COE, 2011) 

(Table 3-11). Table 3-12 shows the same information for Federal channels in Louisiana, and Table 3-13

shows the same information for Federal channels in Mississippi, Alabama, and Florida.

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 beginning 

in the 1800’s (Good et al., 1995, Table 1). The Federal navigation channels in Louisiana identified by 

Good et al. (1995, Table 1) are as follows: (1) GIWW East of the Mississippi River; (2) Mississippi 

River Gulf Outlet; (3) GIWW between the Atchafalaya and Mississippi Rivers; (4) GIWW West of the 

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).

Turner and Cahoon (1987, Table 4-1) and DOI (Table 3-14 of the 2012-2017 WPA/CPA Multisale 

EIS) identified OCS oil- and gas-related channels that bore traffic supporting the OCS Program. Between 

these works and Good et al. (1995, Table 1), channel names do not well agree and a comparison is 

difficult. No channel is exclusively used by OCS Program traffic and only a fraction of the total traffic is 

attributable to OCS use, i.e., approximately 10-13 percent. BOEM compiled Table 3-37 of the 2012-2017 

WPA/CPA Multisale EIS using the information in industry plans to show that, between 2003 and 2008, 

the vast majority (80-90%) of OCS service vessels used service-base facilities in the LCA that are located 

along rivers or that lie within wetlands that are already saline or brackish. Table 3-37 of the 2012-2017 

WPA/CPA Multisale EIS shows that the contribution of OCS Program traffic to bank degradation and 

freshwater wetland loss is minimal.

The GIWW is a Federal, shallow-draft navigation channel constructed to provide a domestic 

connection between Gulf ports after the discovery of oil in East Texas in the early 1900’s, as well as 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.

Direct cumulative impacts include the displacement of wetlands by original channel excavation and 

disposal of the dredged material. Good et al. (1995) estimated that direct impacts from the construction 

of Federal navigation channels were between 58,000 and 96,000 ac (23,472 and 38,850 ha). Indirect

cumulative landlosses resulted from hydrologic modifications, saltwater intrusion, or bank erosion from 

vessel wakes (Wang, 1988). Once cut, navigation canals tend to widen as banks erode and subside, 

depending on the amount of traffic using the channel. Good et al. (1995, Table 1) estimated indirect 

impacts on wetland loss from bank erosion at 35,000 ac (14,164 ha).

The COE reported that the New Orleans District has the largest channel maintenance dredging 

program in the U.S., with an annual average of 70 million yd3 (53.5 million m3

) of material dredged 

(U.S. Dept. of the Army, COE, 2009a). Of that total, COE’s Ocean Disposal Database indicates that the 

New Orleans District has averaged about 21.7 million yd3 (16.6 million m3

) of material dredged per year 

disposed at ODMDS’s over the last 10 years (U.S. Dept. of the Army, COE, 2010a) (Chapter 3.3.3.1). 

Federal channels and canals are maintained throughout the onshore cumulative impact area by COE, 

State, county, commercial, and private interests. Proposals for new and maintenance dredging projects 
Impact-Producing Factors and Scenario 3-35

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, COE schedules surveys every 

2 years on each navigation channel under its responsibility to determine the need for maintenance 

dredging. Dredging cycles may be from 1 to as many as 11 years from channel to channel and from 

channel segment to channel segment. The COE is charged with maintaining all larger navigation 

channels in the cumulative activities area. The COE dredges millions of cubic meters of material per year 

in the cumulative activities area, most of which is under the responsibility of the New Orleans District. 

Some shallower port-access channels may be deepened over the next 10 years to accommodate deeper 

draft vessels. Vessels that support deepwater OCS activities may include those with drafts to about 7 m 

(23 ft).

Construction and maintenance dredging of rivers and navigation channels can furnish sediment for 

beneficial purpose, a practice the COE calls the 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 Louisiana State lands peaked in 1969-1970 (Ko and Day, 2004). 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 dredge 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 considerably 

the potential area available for the beneficial use of dredge materials program (U.S. Dept. of the Army, 

COE, 2009a).

As discussed in Chapter 3.3.3.1, COE’s New Orleans District dredges an average annual 78 million 

yd3 (59,635,279 m3

). Current figures estimate that approximately 38 percent (or 30 million yd3

[22,936,646 m3

]) 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). 

Cumulative Activities Scenario: The construction of Federal channels is not a growth industry that 

would lead to future direct taking of wetlands, and at least one Louisiana channel (Mississippi River Gulf 

Outlet) has been decommissioned and sealed with a rock barrier as of July 2009 (Shaffer et al., 2009). 

Current research has shown that the erosion of canals has slowed from a widening rate of 1.71 m/yr 

(5.61 ft/yr) between 1978 and 1998 to 0.99 m/yr (3.25 ft/yr) between 1998 and 2006 (Thatcher et al., 

2011). “The mean annual rates of total canal widening or narrowing ranged from -6.47 m/year 

(-21.23 ft/year) (measured as shoreline retreat) for the Theodore Ship Channel, Alabama, to 2.58 m/year 

(8.46 ft/year) for the Atchafalaya River, Louisiana (measured as shoreline advancement)” (Thatcher et al., 

2011, Table 7). To estimate the effect of vessel traffic on the erosion of navigational canals, 30 percent of 

all banks were assumed to be armored either by rock rip-rap, degraded rock rip-rap, or with bulkheads 

(Thatcher et al., 2011).

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 in the EPA, CPA, and WPA 

(Table 3-7) and that the average canal is widening at a rate of 0.99 m/year (3.25 ft/year). Gulfwide, this 

results in a total annual landloss of approximately 831 ac/yr (336 ha/yr). Therefore, over the 40-year 

cumulative activities scenario, landloss in Federal navigation channels could total approximately 

33,221 ac (13,444 ha). Total landloss in these areas can be caused by multiple factors, including saltwater 

intrusion, hurricanes, and vessel traffic. The OCS Program-related traffic constitutes a larger percent of 

the total vessel traffic (OCS Program-related and non-OCS Program-related) in the CPA (12-16%) than in 

the WPA (3-5%). All service vessels associated with EPA actions are assumed to use CPA navigational 

canals while inland and constitute less than 1 percent of the total vessel traffic. Assuming that vessel 

traffic alone was the sole source of erosion, the rate of landloss 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, BOEM conservatively estimates the OCS 

Program’s contribution to bank erosion over the 40-year cumulative scenario to be 2,766-3,645 ac 

(1,119-1,475 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.
3-36 Central Planning Area Lease Sales 235, 241, and 247 EIS

In the Louisiana Coastal Master Plan (State of Louisiana, Coastal Protection and Restoration 

Authority, 2012a), it is estimated that up to 1,750 mi2 (4,500 km2

) of land will be lost in the next 50 years 

(or approximately 896,000 ac [362,600 ha] of land in the next 40 years). Using BOEM’s conservative 

estimate of approximately 2,360 km (1,470 mi) of Federal navigation channels, bayous, and rivers 

potentially exposed to OCS traffic in the LCA (Table 3-7) and the average canal widening rate 

of -0.99 m/yr (-3.25 ft/yr), a total landloss of approximately 16,190 ac (6,550 ha) in navigation canals 

may be estimated over the next 40 years. Using this estimate and comparing it with the total expected 

landloss in coastal Louisiana over the next 40 years, BOEM estimates that approximately 2 percent of the 

total landloss in Louisiana will occur due to salt intrusion, hurricanes, and vessel traffic (OCS Programrelated and non-OCS Program-related) in navigation canals. Because OCS Program-related vessel traffic 

constitutes only 12-16 percent of the total vessel traffic in the CPA, BOEM conservatively estimates that 

OCS Program-related vessel traffic would contribute <0.5 percent (or <2,647 ac [1,071 ha]) of the 

landloss in coastal Louisiana in the next 40 years.

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. Subtracting 

projected landlosses of 16,190 ac (6,550 ha) caused by bank widening of navigation channels in the LCA 

from land added or protected by beneficial uses of dredged material, an estimated net gain of 33,800 ac 

(13,700 ha) between the years 2013 and 2063 could occur.

For a more complete and detailed discussion of maintenance dredging and Federal channels, refer to 

Chapter 3.3.4.3 of the 2012-2017 WPA/CPA Multisale EIS. For more information on coastal restoration 

programs, refer to Chapter 3.3.4.4 of this Supplemental EIS.

3.3.4.4. 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 up to 11.4 mi (18.3 km) thick offshore (Gagliano, 1999). Five major deltaic 

deposition 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, page 296). The youngest delta lobe of the Mississippi Delta is the Plaquemines-Balize 

lobe that has been active since the St. Bernard lobe was abandoned about 1,000 years ago. The lower 

Mississippi River has shifted its course to the 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 

LCA experiences relatively high rates of subsidence relative to more stable coastal areas eastward and 

westward (U.S. Dept. of the Army, COE, 2004). 

The first systematic program authorized for coastal restoration in the LCA was the 1990 CWPPRA, 

otherwise known as the “Breaux Act.” Individual CWPPRA projects are designed to protect and restore 

between 10 and 10,000 ac (4 and 4,047 ha), require an average of 5 years to transition from approval to 

construction, and are funded to operate for 20 years (U.S. Government Accountability Office, 2007), 

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 landlosses and ecosystem degradation 

became more apparent, so too appeared the need for a more systematic approach to integrate smaller 

projects with larger projects to restore natural geomorphic structures and processes. Projects have ranged 

from small demonstration projects to projects that cost over $50 million. The COE reports that, as of 

May 2013, there are 196 authorized CWPPRA projects, 99 of which have been completed. Another 

20 projects are under construction, 34 are in the engineering and design phase, and 43 have been 

deauthorized or transferred to another program. The COE projects the creation of over

81,000 “anticipated total acres” (32,780 ha) from constructed projects. Of the 60 projects not yet 

completed as of mid-2013, COE anticipates that those projects will result in 33,297 anticipated total acres 

(13,474 ha) (LaCoast.gov, 2013). Of the 99 completed projects listed on LaCoast.gov (2013), more than 

half were one of three categories types: shoreline protection (29 projects); hydrologic restoration 

(24 projects); or marsh creation (16 projects). The Coast 2050 Report (State of Louisiana, Dept. of 
Impact-Producing Factors and Scenario 3-37

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, 2004) built upon the Coast 2050 Report. The LCA’s restoration strategies 

generally fell into one of the following categories: (1) freshwater diversion; (2) marsh management; 

(3) hydrologic restoration; (4) sediment diversion; (5) vegetative planting; (6) beneficial use of dredge 

material; (7) barrier island restoration; (8) sediment/nutrient trapping; and (9) shoreline protection, as well 

as other types of projects (Louisiana Coastal Wetlands Conservation and Restoration Task Force, 2006, 

Table 1).

Following Hurricanes Katrina and Rita in 2005, an earlier emphasis on coastal or ecosystem 

restoration of the LCA was reordered to at least add an equal emphasis on hurricane flood protection. 

The Department of Defense Appropriations Act of 2006 authorized COE to develop a comprehensive 

hurricane protection analysis to present a full range of flood control, coastal restoration, and hurricane 

protection measures for south Louisiana (U.S. Dept. of the Army, COE, 2009b). The Appropriations Act 

required Louisiana to create a State organization to sponsor the hurricane protection and restoration 

projects that resulted. The State legislature established the Coastal Protection and Restoration Authority 

and charged it with coordinating the efforts of local, State, and Federal agencies to achieve long-term, 

integrated flood control and wetland restoration. The Coastal Protection and Restoration Authority 

developed a comprehensive master plan for a sustainable coast (State of Louisiana, Coastal Protection and 

Restoration Authority, 2007); this plan served as their vision of an integrated program designed to link 

what had once been separate areas of activity—flood protection and coastal restoration. The Coastal 

Protection and Restoration Authority’s Annual Plans prioritize the types of projects undertaken each 

fiscal year. It is not entirely clear how coordination between the State and Federal authorities is 

undertaken in order to develop the range of projects selected for the State’s Coastal Protection and 

Restoration Authority’s Annual Plan and COE’s plan (U.S. Dept. of the Army, COE, 2009a).

The Coastal Protection and Restoration Authority released a Final Coastal Master Plan in 2012. The 

Plan’s objectives focus 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, 2012a). 

There is no simple way to anticipate the following: (1) which projects the State’s Coastal Protection 

and Restoration Authority will admit to its Annual Plan; (2) which projects (among those undertaken for 

COE’s comprehensive range of plans for flood control, coastal restoration, and hurricane protection 

measures for the LCA) will feed into the Coastal Protection and Restoration Authority’s Annual Plan for 

authorization; and (3) ultimately which, if any, of the aforementioned projects will be completed. 

Because these projects are chosen on the basis of annual appropriations, there is no simple way to 

establish projections for land added or preserved over the cumulative activities scenario.

Coastal Impact Assistance Program

The Energy Policy Act of 2005 was signed into law by President George W. Bush on August 8, 2005. 

Section 384 of the Energy Policy Act of 2005 amended Section 31 of the OCSLA (43 U.S.C. § 1356(a)) 

to establish the Coastal Impact Assistance Program (CIAP). 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.

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 up until September 30, 2011. 

In 2011, the Secretary announced that FWS would take over administration of CIAP effective October 1, 

2011, because the program aligned with FWS’s conservation mission and similar grant programs run by 

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 oil-producing 

states for conservation, protection, and restoration of coastal areas. The CIAP 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 
3-38 Central Planning Area Lease Sales 235, 241, and 247 EIS

management plan; and mitigation of the impact of OCS 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, Kenedy, Kleberg, Matagorda, Nueces, Orange, Refugio, San Patricio, 

Victoria, and Willacy Counties

Natural Resource Damage Assessment Trustee Council

The Oil Pollution Act, as provided in 33 U.S.C. § 2706, allowed the designation of certain Federal 

agencies, States, and Indian tribes—collectively known as the Natural Resource Damage Assessment 

Trustee Council (Trustee Council). The Trustee Council is authorized to act on behalf of the public to 

(1) assess natural resource injuries resulting from a discharge of oil or the substantial threat of a discharge 

and response activities and (2) develop and implement a plan(s) for restoration of those injured resources 

(USDOI, 2012). With respect to NRDA for the Deepwater Horizon explosion and oil spill, a list of 

trustees can be found at http://www.gulfspillrestoration.noaa.gov/about-us/co-trustees/. On 

September 27, 2010, the Trustee Council submitted documentation supporting their determination of 

jurisdiction and their intent to conduct restoration planning. Executive Order 13554, signed on October 5, 

2010, recognized the role of the Trustee Council under the Oil Pollution Act and required that the Gulf 

Coast Ecosystem Restoration Task Force support the NRDA process by referring potential ecosystem 

restoration actions to the Trustee Council for consideration. Specifically, Executive Order 13554 

recognized the importance of carefully coordinating the work of the 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 Trustee Council is currently in the early restoration phase, and their data 

collection and analysis are ongoing (USDOI, 2012).

Gulf Coast Ecosystem Restoration Council

The Gulf Coast Ecosystem Restoration Task Force (refer to Chapter 3.3.3.4 of the 2012-2017 

WPA/CPA Multisale EIS) was terminated in December 2012, following release of Executive 

Order 13626 in September 2012 and affirming the Federal Government’s Gulf Coast ecosystem 

restoration efforts in light of the recent passage of the RESTORE Act. The RESTORE Act established a 

mechanism for providing funding to the Gulf region to restore ecosystems and rebuild local economies 

damaged by the Deepwater Horizon oil spill. Additionally, the RESTORE Act established the Gulf 

Restoration Council, an independent entity charged with developing a comprehensive plan for ecosystem 

restoration in the Gulf Coast (Comprehensive Plan), as well as any future revisions to the Comprehensive 

Plan. This Council replaced the Gulf Coast Ecosystem Restoration Task Force in December 2012.

Among its other duties, the Gulf Restoration Council is tasked with identifying projects 

and programs aimed at restoring and protecting the natural resources and ecosystems of 

the Gulf Coast region, to be funded from a portion of the Trust Fund; establishing such 

other advisory committees as may be necessary to assist the Gulf Restoration Council, 

including a scientific advisory committee and a committee to advise the Gulf Restoration 
Impact-Producing Factors and Scenario 3-39

Council on public policy issues; gathering information relevant to Gulf Coast restoration, 

including through research, modeling, and monitoring; and providing an annual report to 

the Congress on implementation progress. Consistent with the RESTORE Act, the 

Comprehensive Plan developed by the Gulf Restoration Council will include provisions 

necessary to fully incorporate the Strategy, projects, and programs recommended by the 

Task Force (The White House, 2012).

3.3.5. Natural Events and Processes

Chapter 3.3.5 of the 2012-2017 WPA/CPA Multisale EIS describes in detail natural events and 

processes in the GOM, including physical oceanography and hurricanes. 

Since 2009, most of the extreme atmospheric events in the GOM have been categorized as tropical 

storms with strong winds, heavy rain, and storm surges causing coastal flooding. However, on 

August 28, 2012, Hurricane Isaac made landfall in southeastern Louisiana as a Category 1 hurricane. 

While there were no reports of moderate or extensive damage to offshore oil or gas infrastructure in the 

GOM, Hurricane Isaac did result in the suspension of small amounts of tarballs and some oil from 

sediments (Mulagabal et al., 2013). This conforms with predictions in the 2012-2017 WPA/CPA 

Multisale EIS analysis and is discussed more fully in Chapter 4.1.1.2.1 of this Supplemental EIS.

CHAPTER 4 

DESCRIPTION OF THE ENVIRONMENT

AND IMPACT ANALYSIS

Description of the Environment and Impact Analysis 4-3 

4. DESCRIPTION OF THE ENVIRONMENT AND IMPACT ANALYSIS

The impacts of 10 WPA and CPA lease sales were analyzed in the Gulf of Mexico OCS Oil and Gas 

Lease Sales: 2012-2017; Western Planning Area Lease Sales 229, 233, 238, 246, and 248; Central 

Planning Area Lease Sales 227, 231, 235, 241, and 247, Final Environmental Impact Statement (2012-

2017 WPA/CPA Multisale EIS) (USDOI, BOEM, 2012b and this analysis was updated in the Gulf of 

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

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

Supplemental EIS) (USDOI, BOEM, 2013a). An analysis of the routine, accidental, and cumulative 

impacts of a CPA proposed action on the environmental, socioeconomic, and cultural resources of the 

GOM can be found in Chapter 4.2.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1 of the 

WPA 233/CPA 231 Supplemental EIS. The 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 

231 Supplemental EIS are hereby incorporated by reference.

The purpose of this Supplemental EIS is to determine if there are significant new circumstances or 

information bearing on the proposed actions or their impacts, as stated in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, and, if so, to disclose those changes and 

conclusions. This includes all relevant new information available since the publication of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. This Supplemental EIS analyzes 

the potential impacts of a CPA proposed action on sensitive coastal environments, offshore marine 

resources, onshore and offshore socioeconomic resources, and cultural resources.

4.1. PROPOSED CENTRAL PLANNING AREA LEASE SALES 235, 241, AND 247

Proposed CPA Lease Sales 235, 241, and 247 are tentatively scheduled to be held in March 2015, 

2016, and 2017, respectively. The proposed CPA lease sale area encompasses about 63 million ac of the 

total CPA area of 66.45 million ac. This area 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 (often the 

Exclusive Economic Zone) in water depths up to approximately 3,346 m (10,978 ft) (Figure 1-1). As of 

February 2014, approximately 43.5 million ac of the proposed CPA lease sale area are currently unleased. 

A CPA proposed action would offer for lease all unleased blocks within the proposed CPA 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; 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.

The DOI is conservative throughout the NEPA process and includes the total area within the CPA for 

environmental review even though the leasing of portions of the CPA (subareas or blocks) can be deferred 

during a Five-Year Program.

Chapter 4.1.1 presents a brief summary of the baseline data for the physical, biological, and 

socioeconomic resources that would potentially be affected by a CPA proposed action or the alternatives. 

For additional information on the baseline data for the physical, biological, and socioeconomic resources 

that would potentially be affected by a CPA proposed action or the alternatives, refer to Chapter 4.2.1 of 

the 2012-2017 WPA/CPA Multisale EIS and to updated information provided in Chapter 4.2.1 of the 

WPA 233/CPA 231 Supplemental EIS.

Chapter 4.1.1 also presents analyses of the potential impacts of routine events, accidental events, and 

cumulative activities associated with a CPA proposed action or the alternatives on these resources. 

Baseline data are considered in the assessment of impacts from proposed CPA Lease Sales 235, 241, and 

247 on these resources. In addition, Appendix B (“Catastrophic Spill Event Analysis”) serves as a 

complement to this chapter and provides additional analysis of the potential impacts of a low-probability 

catastrophic oil spill, which is not reasonably expected and not part of a CPA proposed action, to the 

environmental and cultural resources and the socioeconomic conditions analyzed below.
4-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

The Deepwater Horizon explosion off the Louisiana coast resulted in the largest oil spill in U.S. 

history. An event such as this has the potential to adversely affect multiple resources over a large area. 

The level of adverse effect depends on many factors, including the sensitivity of the resource as well as 

the sensitivity of the environment in which the resource is located. All effects may not initially be seen 

and some could take years to fully develop. The following analyses of impacts from the Deepwater 

Horizon explosion, oil spill, and response on the physical, biological, and socioeconomic resources are 

based on post-Deepwater Horizon credible scientific information that was publicly available at the time 

this 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, the 

Trustee Council of the NRDA for the Deepwater Horizon oil spill continues to study, measure, and 

interpret impacts arising out of that spill. Because the NRDA information has not yet been made 

available to BOEM or the general public, there are thus instances in which BOEM is faced with 

incomplete and unavailable information that may be relevant to evaluating reasonably foreseeable 

significant adverse impacts on the human environment. While incomplete or unavailable information 

could conceivably result in potential future shifts in baseline conditions of habitats that could affect 

BOEM’s decisionmaking, BOEM has determined that there is sufficient basis to proceed with this 

Supplemental EIS while operating on the basis of the most current available data and expertise of 

BOEM’s subject-matter experts. Chapter 4.1.1 and Appendix B provide a summary of existing credible 

scientific evidence related to this issue and BOEM’s evaluation of potential impacts based upon 

theoretical approaches or research methods generally accepted in the scientific community. Despite the 

unavailability of complete information from the NRDA process, BOEM has determined that it can make 

an informed decision even without this incomplete and unavailable information because BOEM utilizes 

the best available scientifically credible information in its decisionmaking process and because, although 

BOEM cannot speculate as to the results of ongoing NRDA studies, BOEM experts can apply other 

scientifically credible information using accepted theoretical approaches and research methods, such as 

information on related or 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. 

Chapter 3.2.1 of this Supplemental EIS provides a brief summary of the information on accidental 

spills that could result from all operations conducted under the OCS Program, as well as information on 

the number and sizes of spills from non-OCS sources. Table 3-12 of the 2012-2017 WPA/CPA Multisale 

EIS provides the number of spills ≥1,000 bbl and <1,000 bbl estimated to occur as a result of a CPA 

proposed action. BOEM estimates that the mean number of spills ≥1,000 bbl for a CPA proposed action 

is <1-1 spill. Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS provides spill rates for several spillsize categories. Chapter 3.2.1.8 and Figures 3-8 through 3-28 of the 2012-2017 WPA/CPA Multisale EIS

describe the probabilities of a spill ≥1,000 bbl occurring and contacting modeled environmental 

resources. For additional information on accidental spills that could result from all operations conducted 

under the OCS Program, as well as information on the number and sizes of spills from non-OCS sources, 

refer to Chapter 3.2.1 of this Supplemental EIS and to Chapter 3.2.1 of the 2012-2017 WPA/CPA 

Multisale EIS.

Analytical Approach

The analyses of potential effects to the wide variety of physical, environmental, and socioeconomic 

resources in the vast area of the GOM and adjacent coastal areas is very complex. Specialized education, 

experience, and technical knowledge are required, as well as familiarity with the numerous impactproducing factors associated with oil and gas activities and other activities that can cause cumulative 

impacts in the area. Knowledge and practical working experience of major environmental laws and 

regulations such as NEPA, the Clean Water Act, Clean Air Act, Coastal Zone Management Act (CZMA), 

Endangered Species Act (ESA), Marine Mammal Protection Act (MMPA), the Magnuson-Stevens 

Fishery Conservation and Management Act, and others are also required.

In order to accomplish this task, BOEM has assembled a multidisciplinary staff with hundreds of 

years of collective experience. The vast majority of this staff has advanced degrees with a high level of 

knowledge related to the particular resources discussed in this chapter. This staff prepares the input to 

BOEM’s lease sale EIS’s, a variety of subsequent postlease NEPA reviews, and are also involved with 
Description of the Environment and Impact Analysis 4-5 

ESA, essential fish habitat (EFH), and CZMA consultations. In addition, this same staff is also directly 

involved with the development of studies conducted by BOEM’s Environmental Studies Program. The 

results of these studies feed directly into our NEPA analyses.

For this Supplemental EIS, BOEM developed a set of assumptions and a scenario, and described the 

impact-producing factors that could occur from routine oil and gas activities, as well as accidental events. 

These assumptions, scenario, and factors are summarized in Chapter 3 of this Supplemental EIS and are 

discussed in detail in Chapter 3 of the 2012-2017 WPA/CPA Multisale EIS. On the basis of these 

assumptions, scenario, and factors, BOEM’s multidisciplinary staff applies its knowledge and experience 

to analyze the potential effects that could arise out of proposed CPA Lease Sales 235, 241, and 247.

For most resources, the conclusions developed by BOEM’s subject-matter experts regarding the 

potential effects of proposed CPA Lease Sales 235, 241, and 247 are necessarily qualitative in nature; 

however, these conclusions are based on the expert opinion and judgment of highly trained subject-matter 

experts. BOEM’s staff approaches this effort in good faith utilizing credible scientific information 

including, but not limited to, information available since the Deepwater Horizon explosion, oil spill, and 

response, and applying this information using accepted methodologies, including numerical modeling of 

data and scientific writing methods to convey the information of the subject-matter experts’ technical 

knowledge and experience. It must also be emphasized that, in arriving at the overall conclusions for 

certain environmental resources (e.g., coastal and marine birds, fisheries, and wetlands), the conclusions 

are not based on impacts to individuals, small groups of animals, or small areas of habitat, but on impacts 

to the resources/populations as a whole. Where relevant information on reasonably foreseeable 

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

determine if it was essential to a reasoned choice among the alternatives. If BOEM’s subject-matter 

experts determined that the incomplete or unavailable information was essential, BOEM made good faith 

efforts to acquire the information. In the event that BOEM was unable to obtain essential information due 

to either impossibility or exorbitant cost, BOEM applied accepted scientific methodologies in place of 

that information. This approach is described in the next subsection on “Incomplete or Unavailable 

Information.”

Over the years, BOEM has developed a suite of lease stipulations and mitigating measures to 

eliminate or ameliorate potential environmental effects. In many instances, these lease stipulations and 

mitigating measures were developed in coordination with other natural resource agencies such as NMFS 

and FWS.

Throughout its effort to prepare this Supplemental EIS, BOEM has made painstaking efforts to 

comply with the spirit and intent of NEPA, to avoid being arbitrary and capricious in its analyses of 

potential environmental effects, and to use adaptive management to respond to new developments related 

to the OCS Program.

Incomplete or Unavailable Information

In the following analyses of physical, environmental, and socioeconomic resources, BOEM identifies 

situations in which its analysis contains incomplete or unavailable information. The major area where 

BOEM is faced with incomplete or unavailable information is in relation to the Deepwater Horizon

explosion, oil spill, and response. Information related to the explosion, oil spill, and response is still 

being collected, interpreted, and analyzed by a myriad of Federal and State agencies. With respect to 

some of this information, including much of the data related to the NRDA process, those in charge of 

analyzing impacts from the spill have not yet shared their data and findings with BOEM or made this 

information publicly available. Therefore, in situations in which BOEM’s subject-matter experts were 

faced with incomplete or unavailable information, the subject-matter experts for each resource utilized the 

most recent publicly available, scientifically credible information from other sources to support the 

conclusions contained in this Supplemental EIS. This information is identified and summarized in 

Chapter 4.1.1 of this Supplemental EIS and is discussed in detail for each resource in Chapter 4.2.1 of 

the 2012-2017 WPA/CPA Multisale EIS. In certain circumstances, identified and described in more 

detail in Chapter 4.1.1 of this Supplemental EIS, BOEM’s subject-matter experts were required to utilize 

accepted methodologies to extrapolate conclusions from existing or new information and to make 

reasoned estimates and developed conclusions regarding the current CPA baseline for resource categories 

and expected impacts from a CPA proposed action given any baseline changes. For reasons described 
4-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

below, there are no changes to the conclusions presented in the 2012-2017 WPA\CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS. 

It is important to note that, barring another catastrophic oil spill, which is a low-probability accidental 

event, the adverse impacts associated with a proposed CPA lease sale are small, even in light of the 

Deepwater Horizon explosion, oil spill, and response. This is because of draft lease sale stipulations and 

BOEM and other Federal and State entities’ mitigating measures. BOEM also imposes site-specific 

mitigations that become conditions of plan or permit approval at the postlease stage. Collectively, these 

measures further reduce the likelihood of adverse impacts.

For the following resources, as with the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS, the subject-matter experts determined that there is incomplete or unavailable 

information that is relevant to reasonably foreseeable significant adverse impacts; however, it is not 

essential to a reasoned choice among alternatives.

• Physical Resources in the CPA: Physical resources (i.e., water quality and air 

quality) within the CPA are likely not continuing to be affected to any discernible 

degree by the Deepwater Horizon explosion, oil spill, and response, based on the best 

available information, including recent sampling data. Although unable to speculate 

as to the results of ongoing NRDA studies, BOEM has determined that the 

incomplete or unavailable information is not essential to a reasoned choice among 

alternatives because BOEM utilizes the best available scientifically credible 

information in its decisionmaking process. Much of the information related to the 

Deepwater Horizon explosion, oil spill, and response may not be available for some 

time, regardless of the costs necessary to obtain this information, as there are 

numerous task forces and interagency groups involved in the production of the 

information. It is not expected that this data would become publicly available in the 

near term, and certainly not within the timeline contemplated in the NEPA analysis 

of this Supplemental EIS. 

• Nonmobile Biological Resources within the CPA: Coastal and offshore biological 

and benthic habitats (i.e., barrier beaches, wetlands, seagrasses, soft bottom benthic 

communities, topographic features, and chemosynthetic and nonchemosynthetic 

communities) and nonmobile benthic species that would be expected to spend their 

entire life cycle in the CPA were likely not affected to any discernible degree by the 

Deepwater Horizon explosion, oil spill, and response, based on the best available 

information, including recent sampling data. Similarly to the analysis of physical 

resources in the CPA described in the preceding paragraph, although unable to 

speculate as to the results of ongoing NRDA studies, BOEM has determined that the 

incomplete or unavailable information regarding nonmobile biological resources is 

not essential to a reasoned choice among alternatives because BOEM utilizes the best 

available scientifically credible information in its decisionmaking process.

• Mobile Biological Resources within or Migrating through the CPA: Certain mobile 

biological resources (i.e., birds, fish, marine mammals, and sea turtles) having ranges 

and/or habitats that may include different areas in the GOM may have individually 

been affected by exposure to oil and/or spill-response activities, provided they were 

in the vicinity of the Deepwater Horizon explosion, oil spill, and response during 

spill conditions. Precise information on the impacts on mobile biological resources 

within or migrating through the CPA is therefore not known, and it is not expected 

that these data would become publicly available within the timeline contemplated in 

the NEPA analysis of this Supplemental EIS. Although unable to speculate as to the 

results of ongoing NRDA studies, BOEM has determined that the incomplete or 

unavailable information is not essential to a reasoned choice among the alternatives 

because the adverse impacts from routine activities associated with a CPA proposed 

action are expected to be small, even in light of how baseline conditions may have 

been changed by the Deepwater Horizon explosion, oil spill, and response. 

Moreover, based on the scientifically credible information that was available and 

applied in Chapter 4.1.1, such as peer-reviewed journals and government reports, 
Description of the Environment and Impact Analysis 4-7 

this incomplete or unavailable information is not essential to a reasoned choice 

among the alternatives because the subject-matter experts for this Supplemental EIS 

have already evaluated the probability and severity of these potential impacts and 

because this incomplete or unavailable information is not essential to understand 

every particular mechanism by which these significant impacts could occur. With 

regard to future potentially low-probability catastrophic spills, any incomplete or 

unavailable information regarding the nature of a very large spill would not be 

essential to a reasoned choice among the alternatives. This is because a catastrophic 

spill and its impacts are not “expected” as a result of a CPA proposed action since 

such a spill remains a low-probability event, particularly in light of improved safety 

and oil-spill-response requirements that have been put in place since the spill.

• Endangered and Threatened Species: BOEM reinitiated consultation with NMFS 

and FWS in light of new information that may become available on these species and 

in light of effects from the Deepwater Horizon explosion, oil spill, and response. 

Pending the completion of the reinitiated ESA section 7 consultation, BOEM has 

prepared an ESA section 7(d) determination (50 CFR § 402.09). Section 7(d) of the 

ESA requires that, after initiation or reinitiation of consultation under section 7(a)(2), 

the Federal agency “shall not make any irreversible or irretrievable commitment of 

resources with respect to the agency action which has the effect of foreclosing the 

formulation or implementation of any reasonable and prudent alternative measures 

which would not violate” section 7(a)(2). BOEM has determined that a CPA 

proposed action during the reinitiated section 7 consultation period is consistent with 

the requirements of ESA section 7(d) because (1) approving and/or conducting a 

proposed CPA lease sale will not foreclose the formulation or implementation of any 

Reasonable and Prudent Alternative measures that may be necessary to avoid 

jeopardy (or the likely destruction or adverse modification of critical habitat) and 

(2) the Secretary of the Interior retains the discretion under OCSLA to deny, suspend, 

or rescind plans and permits authorized under OCSLA at any time, as necessary to 

avoid jeopardy. Lease sales alone do not constitute an irreversible and irretrievable 

commitment of resources. In addition, the results of consultation and any additional 

relevant information on endangered and threatened species can be employed during 

postlease activities to ensure that Reasonable and Prudent Alternative measures are 

not foreclosed. BOEM and BSEE have developed an interim coordination program 

with NMFS and FWS for individual consultations on postlease activities requiring 

permits or plan approvals while formal consultation and development of a new 

Biological Opinion is ongoing.

• Natural Resource Damage Assessment (NRDA) Data: In response to the Deepwater

Horizon explosion, oil spill, and response, a major NRDA is underway to assess 

impacts to all natural resources in the GOM that may have been impacted by the 

resulting spill from the Macondo well, as well as impacts from the spill-response 

operations. The NRDA is mandated by the Oil Pollution Act of 1990. The U.S. 

Department of the Interior is a co-Trustee in the NRDA process, and BOEM is a 

cooperating agency on a Programmatic EIS being prepared as part of the NEPA

analysis for NRDA. However, the NRDA process is being led by the NRDA

Trustees, which include NOAA and DOI (FWS and NPS), but not BOEM. BOEM is 

listed as an affected party for NRDA purposes. At this time, limited data compiled in 

the NRDA process have been made publicly available. Because limited data have 

been made publicly available, most NRDA datasets are not available for BOEM to 

use in its NEPA analyses. BOEM acknowledges that the ability to obtain and use the 

NRDA data in its NEPA analyses could be relevant to reasonably foreseeable 

significant adverse impacts; however, the NRDA data are not essential to a reasoned 

choice among the alternatives. Impacts identified through the NRDA process would 

likely be the same under any alternative and obtaining these data would not help 

inform the decisionmaker on a reasoned choice among those alternatives. This is 

because, as discussed above, the adverse impacts associated with a proposed CPA 
4-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

lease sale are small, even in light of how baseline conditions in the CPA may have 

been changed by the Deepwater Horizon explosion, oil spill, and response. The 

impacts are expected to be small because of BOEM’s lease sale stipulations and 

mitigating measures, site-specific mitigations that become conditions of plan or 

permit approval at the postlease stage, and mitigations required by other State and 

Federal agencies. Even if the NRDA data were essential to a reasoned choice among 

the alternatives, it is not publicly available and much of the data may not become 

available for many years. The NEPA allows for decisions to be made based on 

available scientifically credible information (peer-reviewed journals and studies, 

government reports, etc.) applied using accepted methodologies where the 

incomplete information cannot be obtained or the cost of obtaining is exorbitant. The 

NRDA process is ongoing and there is no timeline on when this information will be 

released. It is not within BOEM’s authority to obtain this information. Cost is not an 

issue in obtaining the information, regardless of whether the cost would be exorbitant 

or not. Instead, the limitations on the NRDA process, including statutory 

requirements under the Oil Pollution Act of 1990, are the determining factors on the 

availability of this information. In light of the fact that the NRDA data may not be 

available for years, BOEM has used accepted scientific methodologies to evaluate 

each resource, as described in this chapter. Since the spill, BOEM’s Gulf of Mexico 

OCS Region’s Environmental Studies Program has continually modified its Studies 

Plan to reflect the Agency’s current information needs for studies that address 

impacts and recovery from the oil spill. The scientific studies conducted by the 

Environmental Studies Program provide some of the data that BOEM relies on in 

making decisions in this Supplemental EIS. BOEM’s proposed studies attempt to 

avoid duplication of study efforts while striving to fill information gaps where 

NRDA studies may not address particular resources and their impacts from the oil 

spill.

• Socioeconomic and Cultural Resources: Incomplete or unavailable information 

related to socioeconomic and cultural impacts (i.e., commercial and recreational 

fishing, recreational resources, archaeological resources, land use and coastal 

infrastructure, demographics, economic factors, and environmental justice) may be 

relevant to reasonably foreseeable adverse impacts on these resources. Although 

unable to speculate as to the results of ongoing NRDA studies, BOEM has 

determined that the incomplete or unavailable information would not be essential to a 

reasoned choice among alternatives because BOEM utilizes the best available 

scientifically credible information in its decisionmaking process. 

This chapter has thoroughly examined the existing credible scientific evidence that is relevant to 

evaluating the reasonably foreseeable significant adverse impacts of the CPA proposed lease sales on the 

human environment. The subject-matter experts that prepared this Supplemental EIS conducted a diligent 

search for pertinent new information, and BOEM’s evaluation of such impacts is based upon theoretical 

approaches or research methods generally accepted in the scientific community. All reasonably 

foreseeable impacts were considered, including impacts that could have catastrophic consequences, even 

if their probability of occurrence is low (Appendix B). Throughout this chapter, where information was 

incomplete or unavailable, BOEM complied with its obligations under NEPA to determine if the 

information was relevant to reasonably foreseeable significant adverse impacts; if so, whether it was 

essential to a reasoned choice among alternatives; and, if it is essential, whether it can be obtained and 

whether the cost of obtaining the information is exorbitant, as well as whether generally accepted 

scientific methodologies can be applied in its place (40 CFR § 1502.22).

4.1.1. Alternative A—The Proposed Action

4.1.1.1. Air Quality

BOEM has reexamined the analysis for air quality presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented below. No 
Description of the Environment and Impact Analysis 4-9 

new significant information was discovered that would alter the impact conclusion for air quality 

presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The 

analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 

231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

A detailed description of air quality and the full analyses of the potential impacts of routine activities 

and accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.1 of the 

2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.1 of the WPA 

233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the cumulative 

impacts is presented below. Any new information that has become available since those documents were 

published is presented below.

As BOEM has previously noted in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS, and despite the new information identified and provided below, there is incomplete or 

unavailable information regarding air quality and potential air impacts. Although final summary 

information and reports on air quality impacts from the Deepwater Horizon explosion, oil spill, and 

response may be forthcoming, USEPA, NOAA, and other agencies obtained and released to the public a 

large number of air quality measurements indicating that air impacts tended to be minor and below 

USEPA’s health-based standards. As there are no continuing sources of air pollution related to the 

Deepwater Horizon explosion, oil spill, and response, BOEM would not expect any additional 

measurements or information to alter the conclusions from currently existing data. In addition, as noted 

below and in Appendix A, there are a number of competing methods and available models for estimating 

and tracking potential air emissions and impacts. Each of these methods and models has inherent 

limitations, particularly with regard to the offshore environment in which a CPA proposed action would 

take place. In acknowledgement of these limitations, BOEM’s subject-matter experts, using their best 

professional judgment and experience, have developed conservative assumptions and modeling 

parameters so as to ensure that the impact conclusions herein are reasonable and not underestimated. As 

such, although there is incomplete or unavailable information on air quality impacts at this time that may 

be relevant to reasonably foreseeable adverse impacts, this information is not essential to a reasoned 

choice among alternatives. Emissions of pollutants into the atmosphere from the routine activities 

associated with a CPA proposed action are projected to have minimal impacts to onshore air quality 

because of the prevailing atmospheric conditions, emission heights, emission rates, and the distance of 

these emissions from the coastline. The impacts of the OCS emissions on the onshore air quality are 

below BOEM’s Significance Levels and the NAAQS. The USEPA commented that BOEM should 

compare model results with the USEPA’s significant impact levels (SIL’s). Therefore, the modeled 

results were compared with the U.S. Environmental Protection Agency’s SIL’s. The modeled 

concentrations for annual nitrogen dioxide (NO2) (0.4 μg/m3

) and 24-hour particulate matter of 

2.5 microns or less (PM2.5) (0.3 μg/m3

) in the Class I area exceeds the U.S. Environmental Protection 

Agency’s SIL’s for annual NO2 (0.1 μg/m3

) and 24-hour PM2.5 (0.07 μg/m3) in the Class I area. Although 

the U.S. Environmental Protection Agency’s SIL’s were exceeded, BOEM expects in practice, if the 

emissions were distributed more realistically across the CPA, that emissions would not exceed the 

U.S. Environmental Protection Agency’s SIL’s. The modeling that was conducted was overly 

conservative. All of the emissions during 1 year for the entire CPA, which would actually be dispersed 

throughout the CPA, were modeled as if they originated in Mississippi Canyon Block 856.

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

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

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

associated with a CPA proposed action are not expected to have concentrations that would change 

onshore air quality classifications.Air Quality Modeling

There are many factors that BOEM evaluates to determine the potential impact occurring from 

offshore air emissions. These include estimates for likely emission sources, likely emission locations, 

emission rates, timeframes, and the likelihood of transport by wind resulting in contact to specified 

environmental features. Sensitivity of the environmental resources and potential effects are addressed in 

the analyses for the specific resources of concern (Chapter 4.1.1). BOEM uses data gathered during 

recent OCS emission inventories, along with a scenario or estimates of future production, to evaluate the 

potential effects of emissions. The scenario provides (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 CPA proposed action.
4-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

BOEM determined projected emissions resulting from the activities on the lease based on known 

emissions from various equipment, such as diesel engines and generators, and the level of offshore 

activity projected in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. 

BOEM then uses a numerical model to calculate the concentration of five pollutants (NO2, sulphur 

dioxide [SO2], particulate matter less than or equal to 2.5 μm [PM2.5], particulate matter less than or equal 

to 10 μm [PM10], and carbon monoxide [CO]) at the receptor. Inputs to the model include the location of 

the emission source 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 carried from the source to the receptor. The 

model output is the concentration of the pollutant at the onshore receptor location at specified time 

intervals. A description of the numerical model, called the Offshore Coastal Dispersion (OCD) Model, 

and its results are summarized in Appendix A. 

OCD Model

The OCD modeling was performed for the CPA Class I and Class II Areas, with the hypothetical 

CPA source located at Mississippi Canyon Block 856, which is approximately 56 mi (90 km) from shore. 

Meteorological data used were from the period 2000 through 2004. The surface data came from 

Patterson, Louisiana, and upper air data came from Slidell, Louisiana. Buoy data for Mississippi Canyon 

Block 856 caome from Buoy 42040. These meteorological data points are the closest, physically, to the 

proposed lease sale area available to BOEM and, therefore, are the best approximation available. BOEM 

calculated scenario-specific emissions based on the Year 2008 Gulfwide Emission Inventory Study

(Wilson et al., 2010) and Rigzone (2009). A spreadsheet was developed based on the findings of this 

study (Billings et al., official communication, 2012). To provide a conservative estimate, BOEM 

assumed a high-range of activity emissions during the year with the greatest amount of activity (e.g., 

drilling and platform and pipeline installation) out of the 40-year analysis period for a CPA proposed 

action. All of the scenario-predicted emissions were then modeled at one location in the CPA. Even with 

all the emissions being attributed to a single point (which would not be the case in reality and thus 

provides a conservative estimate of impacts), the CPA emissions are projected to have minimal impacts to 

onshore air quality. The CPA emissions are within BOEM’s maximum allowable increase for the 

scenario. Methodology, emissions, and modeling results are discussed further in Appendix A. As shown 

in Appendix A, emissions of pollutants into the atmosphere from the activities associated with the OCS 

Program are estimated to have minimal effects on onshore air quality because of the prevailing 

atmospheric conditions, emission rates and mixing heights, and the resulting pollutant concentrations. 

Given that these very conservative estimates of emissions were modeled and still below both agencies’ 

regulatory thresholds, BOEM believes that the potential onshore impacts related to emissions from OCS 

oil and gas activities that may result from a CPA proposed action will not be significant.

BOEM is in the process of a comprehensive assessment of numerical methods (including variety of 

sensitivity analysis, comparison of emission inventories and evaluation of emission scenarios) using 

USEPA-approved models, which will help us to support our scientific statements in future EIS’s. This 

modeling assessment will be helpful when considering that modern air quality models are still in 

development and need to be evaluated before they are widely used for realistic estimations of pollutant 

concentrations over offshore and coastal environments. However, this assessment will take time, 

potentially years, and there will always be some limitations in the application of models. For this reason, 

BOEM is using the OCD Model as it is appropriate for the offshore environment. BOEM’s subjectmatter experts also used their professional judgment in developing and modeling parameters to ensure 

that the results were conservative.

On the basis of OCD modeling for NOx, SOx, PM2.5, PM10, and CO, and the Gulf of Mexico Air 

Quality Study for O3 (Systems Applications International et al., 1995), BOEM is confident that offshore 

OCS oil and gas activities associated with a CPA proposed action will not contribute to exceedances of 

the NAAQS at the shoreline. The inference of conclusions from this study remains appropriate given 

both the decrease in the number of wells drilled and wells producing from wells in water depths <1,000 ft 

(305 m) and the industrial expansions into the deepwater Gulf of Mexico. During the past 5 years 

(2008-2012), the number of wells drilled in shallow water (<1,000-m [305-m] water depth) decreased by 

45 percent from 468 wells in 2008 to 256 wells in 2012. The number of wells producing decreased by 

23 percent from 5,648 to 4,355 wells during the same 5-year timeframe. Simultaneously, production 
Description of the Environment and Impact Analysis 4-11

expansion into deep water is documented in Deepwater Gulf of Mexico 2009: America’s Expanding 

Frontier (USDOI, MMS, 2009a) and in the preceding biennial reports. Over the last 22 years, there has 

been an overall expansion in all phases of deepwater activity. There are approximately 5,700 active 

leases in the Gulf of Mexico OCS, 60 percent of which are in deep water (USDOI, BOEM, 2014a). (Note 

that lease status may change daily; therefore, the current number of existing leases is an approximation.) 

Contrast this to the approximately 5,600 existing Gulf of Mexico leases in 1992, only 27 percent of which 

were in deep water. On average, there are 26 rigs drilling in deep water in 2014, compared with only 

3 rigs in 1992 (USDOI, BOEM, 2014b). This trend is observable in seismic activity, leasing, exploratory 

drilling, field discoveries, and production. With movement of the bulk of activities to deep water, air 

emission-producing sources are moving farther from shore. This further reduces the potential for air 

quality impacts to onshore from a proposed CPA lease sale. Because the bulk of activities from a 

proposed CPA lease sale would be expected to follow this trend, they would be even further removed 

from impacting the shoreline.

The quantity of air pollutants emitted is the direct result of the level of offshore activity. The 

concentrations of the emissions at the shoreline are influenced by the distance between the source of the 

emissions and the receptors. With the simultaneous decrease in both the number of wells drilled and the 

number of wells producing in water depths <1,000 m (305 m) (shallow waters closest to shore) and the 

increase is leases, drilling, and production in water depths >1,000 m (305 m) (deeper waters farther from 

shore), it can be assumed that the emissions related to exploration and production activity have also 

moved farther offshore. As a result of these trends for fewer wells and wells that are farther offshore, the 

OCD modeling results obtained from Systems Applications International et al. (1995), which demonstrate 

no NAAQS exceedances, remain conservative and are still applicable to the discussion of shoreline 

impacts from lease and associated activity projected to result from proposed CPA Lease Sales 235, 241, 

and 247. BOEM, however, supplemented this knowledge with additional data available since that time 

and by running the OCD model accompanying this Supplemental EIS. Emissions from proposed action 

activities as modeled in Appendix A will not significantly contribute to any onshore exceedances of a 

significant impact to onshore NAAQS.

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 from precursor pollutants. To address this 

limitation, BOEM examined available studies on OCS oil and gas activities’ contribution to onshore 

ozone levels, as described below and in Appendix A. These studies confirm that OCS oil and gas 

activities are likely to only have a minimal impact on onshore ozone.

Ozone Model

The Comprehensive Air Quality Model with extensions (CAMx) was used to model contribution 

during an August 2000 ozone episode (Yarwood et al., 2004). The OCS contributions to ozone 

exceedances were minor. Yarwood et al. (2004) used a photochemical model to analyze the Year 2000 

Gulfwide Emissions Inventory (GWEI) and selected the Houston-Galveston-Brazoria nonattainment area 

since it has the most severe ozone problem in the Gulf of Mexico region (System Applications 

International et al., 1995). One of the main relevant findings in Yarwood et al. (2004) is as follows: “The 

average impact of the Year 2000 GWEI emissions on 8-hour ozone levels above 85 ppb in Houston area 

is 0.2 ppb; although larger impacts may occur over the Gulf of Mexico.” Haney et al. (2008) performed a 

modeling investigation using the Year 2000 and Year 2005 GWEI’s in the WPA and CPA to evaluate the 

impact of offshore emissions on offshore and onshore ozone air quality, in which they proposed an 

emission-reduction scenario. They found a particular ozone episode where the onshore impact from all 

offshore oil-and-gas-related sources was small but generally larger than those estimates using the Year 

2000 GWEI. They noticed higher simulated ozone concentrations from 2005 emissions due to increases 

in NOx and VOC concentrations.

Greenhouse Gas Emissions

In response to the FY 2008 Consolidated Appropriations Act, USEPA issued 40 CFR part 98, which 

requires reporting of greenhouse gas emissions, such as carbon dioxide (CO2). 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 per year to report emissions from equipment leaks and venting. On average, 
4-12 Central Planning Area Lease Sales 235, 241, and 247 EIS

the amount of CO2 emissions from a typical well site during operations is about 237-439 tons per year. 

Subpart C of the Green House Gas Reporting Rule requires operators to report greenhouse gas emissions 

from general stationary fuel combustion sources to USEPA. At this point, this is just a reporting 

requirement; there are no specific NAAQS or emission limitations for greenhouse gases.

BOEM has included in Appendix A modeled estimates for certain greenhouse gases that may be 

directly emitted during OCS oil and gas activities. At this time, the greenhouse gas emissions related to 

OCS oil and gas activities are a very small percentage of national emissions, and it would be impossible 

to tease out the impacts from this small incremental addition from global climate change impacts 

attributable to all other global sources. As such, BOEM does not believe that the potential greenhouse 

gas emissions directly attributable to oil and gas activities on the OCS as a result of a CPA proposed 

action are significant to global greenhouse gas levels.

Impacts of Routine and Accidental Events

The following routine activities associated with a CPA proposed action would potentially affect air 

quality: platform construction and emplacement; platform operations; drilling activities; flaring; seismicsurvey and support-vessel operations; pipeline laying and burial operations; evaporation of volatile 

petroleum hydrocarbons during transfers; and fugitive emissions. The impact analysis is based on four 

parameters—emission rates, surface winds, atmospheric stability, and the mixing height. A detailed 

impact analysis of the routine impacts of OCS activities associated with proposed CPA Lease Sales 235, 

241, and 247 on air quality can be found in Chapter 4.2.1.1.2 of the 2012-2017 WPA/CPA Multisale EIS, 

and updated information is provided in Chapter 4.2.1.1 of the WPA 233/CPA 231 Supplemental EIS. 

Emissions of pollutants into the atmosphere from the activities associated with the proposed action are 

projected to have minimal effects on onshore air quality because of the prevailing atmospheric conditions, 

emission rates and mixing heights, and the resulting pollutant concentrations.

The accidental release of hydrocarbons related to a CPA proposed action would result in the emission 

of air pollutants. The OCS oil- and gas-related accidents could include the release of oil, condensate, or 

natural gas or chemicals used offshore or pollutants from the burning of these products. The air pollutants 

include criteria NAAQS pollutants, volatile and semi-volatile organic compounds, H2S, and methane. If a 

fire was associated with the accidental event, it would produce a broad array of pollutants, including all 

NAAQS-regulated primary pollutants, including NO2, CO, SO2, VOC, PM10, and PM2.5. Response 

activities that could impact air quality include in-situ burning, the use of flares to burn gas and oil, and the 

use of dispersants applied from aircraft. Measurements taken during an in-situ burning show that a major 

portion of compounds was consumed in the burn; therefore, pollutant concentrations would be expected 

to be within the NAAQS. These response activities are temporary in nature and occur offshore; therefore, 

there are little expected impacts from these actions to onshore air quality. Accidents involving high 

concentrations of H2S could result in deaths as well as environmental damage. Regulations and NTL’s 

include safeguards and protective measures, which are in place, to protect workers from H2S releases. A 

detailed impact analysis of the accidental impacts that may be associated with proposed CPA Leases Sale 

235, 241, and 247 on air quality can be found in Chapter 4.2.1.1.3 of the 2012-2017 WPA/CPA Multisale 

EIS, and updated information is provided in Chapter 4.2.1.1 of the WPA 233/CPA 231 Supplemental EIS. 

Other emissions of pollutants into the atmosphere from accidental events as a result of a CPA proposed 

action are not projected to have significant impacts on onshore air quality because of the prevailing 

atmospheric conditions, emissions height, emission rates, and the distance of these emissions from the 

coastline.

Summary and Conclusion

BOEM has reexamined the analysis for air quality presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented above. No 

new significant information was discovered that would alter the impact conclusion for air quality 

presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The 

OCD modeling results (included in Appendix A) confirms BOEM’s conclusions in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS that offshore activities would not 

result in exceedances of the NAAQS at the shoreline. The only potential exception is for ozone, where 

there may be some minimal contribution to ozone at the shoreline. Ozone levels are on a declining trend 
Description of the Environment and Impact Analysis 4-13

because of air-pollution control measures that have been implemented by the States. This downward 

trend is expected to continue as a result of local as well as nationwide air-pollution control efforts.

Cumulative Impacts

Background/Introduction 

An impact analysis for cumulative impacts in the CPA is described in this chapter. 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 from OCS sources during the 40-year analysis period.

The activities in the cumulative scenario that could potentially impact onshore air quality include a 

CPA proposed action and the OCS Program, State oil and gas programs, other major offshore but nonOCS oil- and gas-related factors influencing the offshore environments (such as sand borrowing and 

transportation), onshore non-OCS oil- and gas-related activities such as emissions from industry and 

mobile sources (cars/trucks) related to human activities, onshore non-OCS oil- and gas-related sources 

unrelated to human activities (such as forest fires), accidental releases such as oil spills, accidental 

releases of hydrogen sulfide, natural events (e.g., hurricanes), and catastrophic oil spills. 

Emissions contributing to air quality degradation come from many sources. The NAAQS include 

ozone, particulate matter, nitrous dioxide, carbon monoxide, and sulfur dioxide. Air pollutants on the 

NAAQS list are commonly referred to as criteria pollutants. Although these pollutants can all occur 

naturally, elevated levels are often the result of anthropogenic activities.

Ozone pollution is mainly a daytime phenomenon, occurring during the summer months. The 

concentration of ozone in the air is determined not only by the amounts of ozone precursor chemicals but 

also by weather and climate factors. Strong sunlight, warm temperatures, stagnant high-pressure weather 

systems, and low wind speeds cause ground-level ozone to form and accumulate in harmful concentration 

in the air. Ozone is not emitted directly into the air. Ozone is a secondary pollutant formed in the 

presence of sunlight from the reaction of volatile organic compounds (VOC’s) and NO2. Most emissions 

sources of ozone precursor pollutants (NO2, and VOC) are onshore. Emissions sources of ozone 

precursor pollutants include the following: vehicles such as automobiles, trucks, buses, aircraft, and 

locomotives; construction equipment; lawn and garden equipment; sources that combust fuel, such as 

large industries and utilities; small industries such as gas stations and print shops; and consumer products, 

including some paints and cleaners. In addition, biogenic, or natural emissions from trees and plants, are 

a major source of VOC’s. According to the USEPA, automobiles and other mobile sources contribute 

about one-half of the NOx that is emitted. According to NOAA, power plants emit about one-quarter of 

the total U.S. human-made contribution of NOx to the atmosphere. All other sources of NOx emissions 

account for one-quarter of the United States’ totals. The total impact from the combined onshore and 

offshore emissions would be significant to the ozone nonattainment areas in southeast Texas and the 

parishes near Baton Rouge, Louisiana.

OCS Oil- and Gas-Related Impacts 

The OCS oil- and gas-related impacts include the drilling of exploration, delineation, and 

development wells; platform installation; and service-vessel trips, flaring, and fugitive emissions. 

Routine oil spills are also possible. Emission trends from Gulfwide platform sources from 2000, 2005, 

2008, and 2011 show that emissions offshore show little variance across sampling intervals. Emissions of 

pollutants into the atmosphere from activities associated with the OCS Program are not projected to have 

significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates 

and heights, and the resulting pollutant concentrations. Onshore impacts on air quality from emissions 

from OCS activities are estimated to be within Prevention of Significant Deterioration (PSD) Class II 

allowable increments. The modeling results indicate that the cumulative impacts to a PSD Class I Area 

are well within the PSD Class I allowable increment (Wheeler et al., 2008).

Portions of the Gulf Coast have ozone levels that exceed the Federal air quality standard. Ozone 

levels are on a declining trend because of air-pollution control measures that have been implemented by 

the Gulf Coast States. This downward trend is expected to continue as a result of local as well as 

nationwide air-pollution control efforts. However, a more stringent air quality standard has recently been 

implemented by USEPA, which may result in increasing the number of parishes/counties in the coastal 

states in violation of the Federal ozone standard. There is also a proposal to further decrease the ozone 
4-14 Central Planning Area Lease Sales 235, 241, and 247 EIS

standard. If the ozone standard was lowered, although OCS emissions from a CPA proposed action 

would not vary, the OCS emissions in those newly designated areas would have an incrementally larger 

contribution to the onshore ozone levels. Although air quality is improving, the number of areas in 

nonattainment could increase due to more stringent standards (USEPA, 2010).

The Gulf Coast has significant visibility impairment from anthropogenic emission sources. Area 

visibility is expected to improve somewhat as a result of regional and national programs to reduce 

emissions (USEPA, 2013b). The Gulf Coast visibility is expected to improve somewhat as a result of 

regional and national programs to reduce emissions. However, the incremental contribution from a CPA 

proposed action would be very small and would have an insignificant effect on ozone levels in onshore 

ozone nonattainment areas. This minimal impact would not be a contributing factor to the States’ 

schedule for attainment. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 

241, and 247.

A spill could result in the loss of crude oil, crude oil with a mixture of natural gas, or refined fuel. Air 

quality could be affected by the additional response vessel traffic, volatilization of components of the oil, 

and natural gas if released. Impacts from individual spills would be localized and temporary.

The safety issues related to an accidental release of hydrogen sulfide include the following: irritation, 

injury, and lethality from leaks; exposure to sulfur oxides produced by flaring; equipment and pipeline 

corrosion; and outgassing and volatilization from spilled oil.

In the event of a low-probability catastrophic spill, though not reasonably foreseeable and not part of 

a CPA proposed action, oil may be burned to prevent it from entering sensitive habitats. The USEPA 

released two peer-reviewed reports concerning dioxins emitted during the controlled burns of oil during 

the Deepwater Horizon explosion, oil spill, and response (Aurell and Gullett, 2010; Schaum et al., 2010). 

Dioxins is a category that describes a group of hundreds of potentially cancer-causing chemicals that can 

be formed during combustion or burning. The reports found that, while small amounts of dioxins were 

created by the burns, the levels that workers and residents would have been exposed to were below 

USEPA’s levels of concern. For more information on the potential impacts of a low-probability 

catastrophic event, refer to Appendix B.3.1.1. 

The incremental contribution of a CPA proposed action to the cumulative impacts would be minimal. 

Portions of the Gulf Coast onshore areas have ozone levels that exceed the Federal air quality standard, 

but the incremental contribution from a CPA proposed action would be very small. The cumulative 

contribution to visibility impairment from a CPA proposed action is also expected to be very small. Area 

visibility is expected to improve somewhat as a result of regional and national programs to reduce 

emissions. A CPA proposed action would have an insignificant effect on ozone levels in ozone 

nonattainment areas and would not interfere with the States’ schedule for compliance with the NAAQS. 

A routine OCS oil- and gas-related spill is not likely to impact onshore air quality because of the distance 

to shore. However, it would be possible for a spill from an OCS pipeline rupture to occur in State waters. 

Such a spill would have the potential to impact onshore air quality. Pipelines are built with safety devices 

to minimize pipeline spills. Because of the distance between an offshore low-probability catastrophic 

spill and the shore, it is unlikely that a low-probability catastrophic spill, should it occur, could adversely 

impact onshore air quality.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related activities that generate criteria pollutants include industrial activities in 

territorial seas and coastal waters, industrial and transportation activities that occur onshore, and naturally 

occurring events onshore such as forest fires. Hurricanes are natural events that can cause emissions 

when they cause structural damage that result in oil spills or gas releases. Further air emissions are 

generated by the additional traffic from response vessels, uncontrolled or controlled burns, and ultimately, 

new repairs and construction to pipelines or platforms.

State oil and gas programs onshore, in territorial seas, and in coastal waters also generate emissions 

that affect onshore air quality. These emissions are regulated by State agencies and/or USEPA. 

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

other efforts, and as a result, constitute minor impacts to onshore air quality.

Major onshore emission sources from non-OCS oil- and gas-related activities include power 

generation, industrial processing, manufacturing, refineries, commercial and home heating, naturally 
Description of the Environment and Impact Analysis 4-15

occurring forest fires, and motor vehicles. One other NAAQS pollutant, lead, is not associated with 

offshore oil and gas activity so it is not discussed below as cumulative impacts relative to a CPA 

proposed action and are not useful for purposes of NEPA. 

The Gulf Coast has significant visibility impairment from anthropogenic emission sources. Area 

visibility is expected to improve somewhat as a result of regional and national programs to reduce 

emissions (USEPA, 2013b).

A spill such as from State oil and gas activity or from a tanker carrying imported oil could result in 

the loss of crude oil, crude oil with a mixture of natural gas, or refined fuel. Air quality would be affected 

by the additional response vessel traffic, volatilization of components of the oil, and natural gas if 

released. Impacts from individual spills would tend to be localized and temporary.

The safety issue related to an accidental release of hydrogen sulfide is described in Chapter 3.1.1.9. 

The same safety precautions and regulations described for a CPA proposed action are applicable to the 

non-OCS oil- and gas-related scenario. That is, a typical safety zone is usually established in an area with 

the concentration of hydrogen sulfide greater than 20 parts per million (ppm) from the source or a 

platform. 

The effects of hurricanes on the offshore infrastructure are described in Chapter 3.3.5 of this 

Supplemental EIS, Chapter 3.3.5.2 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 3.3.5 of the 

WPA 233/CPA 231 Supplemental EIS. Hurricanes mainly cause damage to offshore infrastructures and 

pipelines, which may result in an oil spill. For the cumulative scenario, hurricanes could also damage 

non-OCS oil- and gas-related infrastructure such as platforms and pipelines in State waters. Any 

emissions from non-OCS oil-spill and response activities that occur in State territorial seas or waters are 

expected to be the same as a CPA proposed action and to have minimum effects on onshore air quality. 

Most emissions sources of ozone precursor pollutants (NO2, and VOC) are onshore. Emissions 

sources of ozone precursor pollutants include the following: vehicles such as automobiles, trucks, buses, 

aircraft, and locomotives; construction equipment; lawn and garden equipment; sources that combust fuel, 

such as large industries and utilities; small industries such as gas stations and print shops; and consumer 

products, including some paints and cleaners. In addition, biogenic, or natural emissions from trees and 

plants, are a major source of VOC’s. According to USEPA, automobiles and other mobile sources 

contribute about half of the NOx that is emitted. According to NOAA, power plants emit about onequarter of the total U.S. human-made contribution of NOx to the atmosphere. All other sources of NOx 

emissions, combined, account for one-quarter of the United States’ totals.

Shore-based sources of PM2.5 include all types of combustion activities related to both human 

activities and naturally occurring sources. Sources range from large and highly regulated industrial 

sources down to sources related to activities of an individual such as trash burning. Some of the most 

cited additional sources include fuel burning associated with motor vehicles, power plants, and wood 

burning, and certain industrial processes.

Fine particulate matter can also form when gases from burning fuels react with sunlight and water 

vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial 

processes. Sources of coarse particles, PM10, include crushing or grinding operations and dust from 

paved or unpaved roads.

Sources of SOx include all types of activities ranging from large, highly regulated industrial sources, 

down to sources related to individual human activities such as outdoor grilling. Fossil fuels contain 

varying amounts of sulfur. Over 65 percent of the SOx released to the air is attributable to electric utilities 

that burn coal. Some additional commonly cited sources of SOx include pulp and paper mills, petroleum 

refining, and nonferrous smelters. Fuel burning associated with motor vehicle usage is another source.

Sources of NOx include all types of activities ranging from large, highly regulated industrial sources 

down to sources related to the activities of individual people, for example, the use of personal water craft 

(e.g., jet skis). Some of the most common anthropogenic sources of NOx include motor vehicles, electric 

utilities, and other industrial commercial and residential sources that burn fuels. Because NOx is a highly 

reactive chemical, it can contribute to ozone formation in the presence of VOC’s in the presence of heat 

and sunlight.

Sources of CO include all types of activities ranging from large, highly regulated industrial sources, 

down to sources related to individual human activities such as tobacco smoke and using gasoline-powered 

equipment or generators. Some of the most common CO sources include residential sources that burn 

fuel and motor vehicles. According to USEPA, motor vehicles account for up to 90 percent of the CO

emissions in urban areas.
4-16 Central Planning Area Lease Sales 235, 241, and 247 EIS

Other major factors influencing coastal environments, such as sand borrowing and transportation in 

State territorial waters, also generate emissions that can affect air quality. These emissions are regulated 

by State agencies and/or USEPA. Reductions have been achieved through the use of low sulfur fuels and 

catalytic reduction and other efforts, and as a result, constitute minor impacts to onshore air quality.

Summary and Conclusion

BOEM has reexamined the analysis for air quality presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented above.

Emissions of pollutants into the atmosphere from activities associated with the OCS Program are not 

projected to have significant effects on onshore air quality because of the prevailing atmospheric 

conditions, emission rates and heights, and the resulting pollutant concentrations. Ozone precursors, NOx 

and VOC’s, are shown to have more ozone-emitting sources present onshore. Onshore impacts on air 

quality from emissions from OCS activities are estimated to be within PSD Class II allowable increments. 

The modeling results indicate that the cumulative impacts to a PSD Class I Area are well within the PSD 

Class I allowable increment.

Ozone levels are on a declining trend because of air-pollution control measures that have been 

implemented by the States. This downward trend is expected to continue as a result of local, as well as 

nationwide, air-pollution control efforts.

The Gulf Coast has significant visibility impairment from anthropogenic emission sources. Area 

visibility is expected to improve somewhat as a result of regional and national programs to reduce 

emissions.

Based on the discussion above and modeled impacts in Appendix A, the incremental contribution of 

a CPA proposed action to the cumulative impacts is not significant. The incremental contribution of a 

CPA proposed action to the cumulative impacts would likewise not significantly affect coastal 

nonattainment areas. The cumulative contribution to visibility impairment from a CPA proposed action 

would also not be significant.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of State and Federal databases, including updates to regulations, was conducted to determine 

the availability of recent information. It has been discovered that Birmingham, Alabama, is no longer in 

nonattainment for any NAAQS criteria pollutant.

BOEM calculated scenario-specific emissions based on the Year 2008 Gulfwide Emission Inventory 

Study (Wilson et al., 2010) and Rigzone (2009). Likewise, BOEM conducted OCD modeling on activity 

that will result from a lease sale using the scenarios for OCS activities in the CPA. These results are 

presented in Table A-1 (Appendix A). The modeled impacts are below BOEM’s maximum allowable 

increases, NAAQS, and the U.S. Environmental Protection Agency’s SIL’s for all the criteria pollutants 

except for the annual NOx and the 24-hour PM2.5 for PSD Class I areas. Although the SIL’s were 

exceeded, BOEM expects in practice, if the emissions were distributed more realistically across the CPA, 

that emissions would not exceed the SIL; and thus, actual emissions likely to result from a CPA proposed 

action would likely not be significant. The modeling that was conducted was overly conservative. All 

the emissions during 1 year for the entire CPA, which would actually be dispersed throughout the CPA, 

were modeled as if they originated in Mississippi Canyon Block 856.

Although final summary information and reports on air quality impacts from the Deepwater Horizon

explosion, oil spill, and response may be forthcoming, USEPA, NOAA, and other agencies obtained and 

released to the public a large number of air quality measurements indicating that air impacts tended to be 

minor and below USEPA’s health-based standards. As there are no continuing sources of air pollution 

related to the Deepwater Horizon explosion, oil spill, and response, BOEM would not expect any 

additional measurements or information to alter the conclusions from currently existing data. As such, 

although there is incomplete or unavailable information on air quality impacts at this time that may be 

relevant to reasonably foreseeable adverse impacts, this information is not essential to a reasoned choice 

among alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS.
Description of the Environment and Impact Analysis 4-17

4.1.1.2. Water Quality

4.1.1.2.1. Coastal Waters

BOEM has reexamined the analysis for coastal water quality presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for coastal 

water quality presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated 

in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

A detailed description of water quality and the full analyses of the potential impacts of routine 

activities and accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.2 of 

the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.2 of the 

WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the 

cumulative impacts is presented below. The following information is a summary of the resource 

description incorporated from the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. Any new information that has become available since those documents were 

published is presented below.

A detailed description of coastal waters can be found in Chapter 4.2.1.2.1 of the 2012-2017 

WPA/CPA Multisale EIS.

Impacts of Routine and Accidental Events

The routine activities associated with a CPA proposed action that would impact water quality include 

the following: discharges during drilling of exploration and development wells; structure installation and 

removal; discharges during production; installation of pipelines; workovers of wells; maintenance 

dredging of existing navigational canals; service-vessel discharges; and nonpoint-source runoff from 

platforms and OCS Program-related vessels. The primary impacting sources to water quality in coastal 

waters are point-source and storm-water discharges from support facilities, vessel discharges, and 

nonpoint-source runoff. These activities are not only highly regulated but also localized and temporary in 

nature. The impacts to coastal water quality from routine activities associated with a CPA proposed 

action should be minimal because of the distance to shore of most routine activities, USEPA and USCG 

regulations that restrict discharges, and few, if any, new pipeline landfalls or onshore facilities would be 

constructed. A detailed impact analysis of the routine impacts of OCS activities associated with proposed 

CPA Lease Sales 235, 241, and 247 on coastal waters can be found in Chapter 4.2.1.2.1.2 of the 2012-

2017 WPA/CPA Multisale EIS, and updated information can be found in Chapter 4.2.1.2.1 of the WPA 

233/CPA 231 Supplemental EIS.

Accidental events associated with a CPA proposed action that could impact coastal water quality

include spills of oil and refined hydrocarbons, releases of natural gas, usage of chemical dispersants in oil 

spill response, spills of chemicals or drilling fluids, loss of well control, collisions, or other malfunctions 

that would result in such spills. Accidental events associated with a CPA proposed action that could 

impact coastal water quality include spills of oil and refined hydrocarbons, releases of natural gas and 

condensate, usage of chemical dispersants in oil-spill response, and spills of chemicals or drilling fluids. 

The loss of well control, pipeline failures, collisions, or other malfunctions could result in such spills. 

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

also impact the environment through, for example, increased vessel traffic, hydromodification, and the 

application of dispersants. In addition to response efforts, natural processes can physically, chemically, 

and biologically degrade oil over time. For coastal spills, two additional factors that must be considered 

are the shallowness of the area and the proximity of the spill to shore. Chemicals used in the oil and gas 

industry are not a significant risk in the event of a spill because they are either nontoxic, are used in minor 

quantities, or are only used on a noncontinuous basis. Spills from collisions are not expected to be 

significant because collisions occur infrequently. A detailed impact analysis of the accidental impacts 

that may be associated with proposed CPA Lease Sales 235, 241, and 247 on coastal waters can be found 

in Chapter 4.2.1.2.1.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information can be found 

in Chapter 4.2.1.2.1 of the WPA 233/CPA 231 Supplemental EIS. Accidental spills as a result of a lowprobability catastrophic event are discussed in Appendix B of this Supplemental EIS.
4-18 Central Planning Area Lease Sales 235, 241, and 247 EIS

Summary and Conclusion 

BOEM has reexamined the analysis for coastal water quality presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for coastal 

water quality presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS, as these newly available studies confirmed earlier estimates of hydrocarbon releases and noted the 

overall return of pre-spill polycyclic aromatic hydrocarbon (PAH) concentrations thus far. Dispersant

studies continue to illustrate the ongoing debate on the use of dispersant as a remediation tool. 

Regulations relevant to the quality of offshore waters continue to be implemented and updated to more 

stringent standards. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

Cumulative Impacts

Background/Introduction 

Activities in the cumulative scenario that could impact coastal water quality generally include the 

broad categories of a CPA proposed action and the OCS Program, alternative energy activities, alternate 

use programs for platforms, sand borrowing, State oil and gas activity, the activities of other Federal 

agencies (including the military), natural events or processes, and activities related to the direct or indirect 

use of land and waterways by the human population (e.g., urbanization, agricultural practices, coastal 

industry, and municipal wastes). Many of these categories would cause some of the same specific 

impacts (e.g., vessel traffic would occur for all of those categories except natural processes).

OCS Oil- and Gas-Related Impacts 

The OCS oil- and gas-related impacts include erosion and runoff, sediment disturbance and turbidity, 

vessel discharges, and accidental releases of oil, gas, or chemicals. Further discussion of these impacts is 

presented below.

Erosion and runoff from nonpoint sources degrade water quality. Nonpoint-source runoff from 

onshore support facilities could result from OCS oil- and gas-related activities; however, as discussed 

below, OCS activities are not the leading source of contaminants that impair coastal water quality. The 

leading source of contaminants that impair coastal water quality is urban runoff.

Sediment disturbance and turbidity may result from nearshore pipeline installation, maintenance 

dredging, and disposal of dredge materials. These impacts generally degrade water quality locally and are 

not expected to last for long periods of time.

Since the marine environment is a dynamic system, sediment quality and water quality can affect 

each other. For example, a contaminant may react with the mineral particles in the sediment and be 

removed from the water column (e.g., adsorption). Thus, under appropriate conditions, sediments can 

serve as sinks for contaminants such as metals, nutrients, or organic compounds. However, if sediments 

are (re)suspended (e.g., due to dredging or a storm event), the resuspension can lead to a temporary shift 

in water quality, including a localized and temporal release of any formally sorbed metals as well as 

nutrient recycling (Caetano et al., 2003; Fanning et al., 1982). Additionally, sediment disturbances from 

storms, especially hurricanes, may also lead to any buried coastal oil being released, as was seen by the 

deposition of Deepwater Horizon tarballs on some beaches after Hurricane Isaac (Burdeau and Reeves, 

2012; Overton, official communication, 2012).

Vessel discharges can degrade water quality. Vessels may be service vessels supporting a CPA 

proposed action or OCS oil- and gas-related activities. Fortunately, for many types of vessels, most 

discharges are treated or otherwise managed prior to release through regulations administered by USCG 

and/or USEPA, and many regulations are becoming more stringent. The USCG Ballast Water 

Management Program became mandatory for some vessels in 2004 (33 CFR part 151 subparts C and D) 

(USDHS, CG, 2012b). The goal of the program was designed to prevent the introduction of 

nonindigenous (invasive) species that would affect local water quality. The USCG is increasing its 

regulations on ballast water management by establishing a standard for the allowable concentration of 

living organisms in ballast water discharged from ships in waters of the U.S and by establishing an 
Description of the Environment and Impact Analysis 4-19

approval process for ballast water management systems. The final rule was published on March 23, 2012, 

in the Federal Register and became effective on June 21, 2012 (USDHS, CG, 2012b). The final Vessel 

General Permit (VGP), which was issued by USEPA, became effective on December 19, 2008, and was 

an addition to already existing NPDES permit requirements. The permit strengthened the NPDES 

regulations so that discharges incidental to the normal operation of vessels operating as a means of 

transportation were no longer excluded unless exempted by Congressional legislation. On March 28,

2013, USEPA reissued the VGP for another 5 years (USEPA, 2013a). The reissued permit, the 2013 

VGP, superseded the 2008 VGP on December 19, 2013. The 2013 VGP continues to regulate 26 specific 

discharge categories that were contained in the 2008 VGP and is more stringent because the permit 

contains numeric ballast water discharge limits for most vessels and more stringent effluent limits for oilto-sea interfaces and exhaust gas scrubber washwater (USEPA, 2013c). The draft Small Vessel General 

Permit (sVGP), once finalized, will authorize discharges incidental to the normal operation of nonmilitary 

and nonrecreational vessels less than 79 ft (24 m) in length (USEPA, 2011a). These regulations should 

minimize the cumulative impacts of vessel activities.

Accidental releases of oil, gas, or chemicals would degrade water quality during and after the spill 

until either the spill is cleaned up or natural processes degrade or disperse the spill. These accidental 

releases could be a result of a CPA proposed action or ongoing OCS activity. The impacts of lowprobability catastrophic spills, though not reasonably foreseeable and not part of a CPA proposed action, 

are discussed in Appendix B. A low-probability catastrophic event would not be expected to occur in 

coastal waters, but a low-probability catastrophic spill in offshore waters could affect coastal waters. For 

example, the oil spill resulting from the Deepwater Horizon explosion impacted coastal waters and 

sediments in Louisiana, Mississippi, Alabama, and Florida. The extent of impact from a spill depends on 

the release location and the behavior and fate of oil in the water column (e.g., the movement of oil and the 

rate and nature of weathering), which, in turn, depends on oceanographic and meteorological conditions

at the time (refer to Appendices A.2 and A.3 of the 2012-2017 WPA/CPA Multisale EIS). The effect on 

coastal water quality from spills estimated to occur from a CPA proposed action are expected to be 

minimal relative to the cumulative effects from hydrocarbon inputs from other sources such as river 

outflow, industrial discharges, and bilge water releases, as discussed in the National Research Council’s 

report Oil in the Sea (NRC, 2003).

A major hurricane can affect OCS activities and result in a greater number of coastal oil and chemical 

spill events with increased spill volume and oil-spill-response times. In the case of an accidental event, it 

is likely that response efforts would reduce the amount of oil. Chapter 3.2.1.9 of this Supplemental EIS 

and Chapter 3.2.1.9 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS provide further discussion of oil-spill-response considerations. Coastal water quality would not only 

be impacted by the oil, gas, and their respective components but also to some degree from cleanup and 

mitigation efforts. Increased vessel traffic, hydromodification (e.g., dredging, berm building, boom 

deployment), and the addition of dispersants and methanol to the marine environment in an effort to 

contain, mitigate, or clean up the oil may also tax the environment.

Non-OCS Oil- and Gas-Related Impacts

Activities not related to a CPA proposed action or the OCS Program that may impact coastal waters 

include State oil and gas activities, alternative energy activities, alternate use programs for platforms, 

sand borrowing, the activities of other Federal agencies (including the military), natural events or 

processes, and activities related to the direct or indirect use of land and waterways by the human 

population. These activities may result in erosion and runoff, sediment disturbance and turbidity, vessel 

discharges, and accidental releases of oil, gas, or chemicals. Further discussion on these impacts is 

described below.

Water quality in coastal waters of the northern Gulf of Mexico is highly influenced by season. 

Seasonality influences salinity and dissolved oxygen, nutrient content, temperature, pH and Eh, 

pathogens, turbidity, metals, and organic compounds. Furthermore, as noted above, it is also important to 

consider sediment quality as sediment quality can affect water quality.

Erosion and runoff from nonpoint sources degrade water quality. Nonpoint-source runoff could result

from State oil and gas activities and other industries and coastal development. The leading source of 

contaminants that impair coastal water quality is urban runoff. Urban runoff can include suspended 

solids, heavy metals and pesticides, oil and grease, nutrients, and organic matter. Urban runoff increases 
4-20 Central Planning Area Lease Sales 235, 241, and 247 EIS

with population growth, and the Gulf Coast region has experienced a 109 percent population growth since 

1970, with an additional expected 15 percent increase by 2020 (USDOC, NOAA, 2011a). The National 

Research Council (2003, Table I-4, page 237) estimated that, on average, approximately 26,324 bbl of oil 

per year entered Gulf waters from petrochemical and oil refinery industries in Louisiana and Texas. 

Chapter 3.1.1.7 of this Supplemental EIS and Chapter 3.1.1.7 of the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS discuss the various sources of petroleum hydrocarbons 

that can enter the Gulf of Mexico in further detail. The natural emptying of rivers into the GOM as part 

of the water cycle may introduce chemical and physical factors that alter the condition of the natural 

water through both natural and anthropogenic sources, such as the addition of waterborne pollutants and 

inflowing waters of different temperature, as well as inputs to the GOM from groundwater discharge and 

precipitation. The Mississippi River introduced approximately 3,680,938 bbl of oil and grease per year 

from land-based sources (NRC, 2003, Table I-9, page 242) into the waters of the Gulf. Nutrients carried 

in waters of the Mississippi River contribute to seasonal formation of the hypoxic zone on the LouisianaTexas shelf. The USEPA has regulatory programs designed to protect the waters that enter the Gulf, 

including the regulation of point-source discharges. 

Sediment disturbance and turbidity may result from nearshore pipeline installation, maintenance 

dredging, disposal of dredge materials, sand borrowing, sediment deposition from rivers, and hurricanes. 

Turbidity is also influenced by the season. These impacts may be the result of State oil and gas activities, 

the activities of other Federal agencies, and natural processes. Dredging projects related to restoration or 

flood prevention measures may be directed by the Federal Government for the benefit of growing coastal 

populations. The COE and State permits would require that the turbidity impacts due to pipeline 

installation be mitigated by using turbidity screens and other turbidity reduction or confinement 

equipment. These impacts generally degrade water quality locally and are not expected to last for long 

periods of time.

Vessel discharges can degrade water quality. Vessels may be service vessels supporting State oil and 

gas activities. However, the vessels may also be vessels used for shipping, fishing, military activities, or 

recreational boating. Fortunately, for many types of vessels, most discharges are treated or otherwise 

managed prior to release through regulations administered by USCG and/or USEPA, and many 

regulations such as the USCG Ballast Water Management Program and the U.S. Environmental 

Protection Agency’s VGP and sVGP are becoming more stringent as discussed in further detail above. A 

Congressional moratorium exempted all incidental discharges, with the exception of ballast water, from 

commercial fishing vessels and nonrecreational, nonmilitary vessels less than 79 ft (24 m) in length, but 

the moratorium expired on December 18, 2013. The sVGP will provide coverage for those vessels 

(USEPA, 2011a) once finalized. These regulations should minimize the cumulative impacts of vessel 

activities.

Accidental releases of oil, gas, or chemicals would degrade water quality during and after the spill 

until either the spill is cleaned up or natural processes degrade or disperse the spill. These accidental 

releases could be a result of State oil and gas activity, the transport of commodities to ports, and/or coastal 

industries. The extent of impact from a spill depends on the release location and the behavior and fate of 

oil in the water column (e.g., the movement of oil and the rate and nature of weathering), which, in turn, 

depends on oceanographic and meteorological conditions at the time.

A major hurricane can affect State oil and gas activities and result in a greater number of coastal oil 

and chemical spill events with increased spill volume and oil-spill-response times. In the case of an 

accidental event, it is likely that response efforts would reduce the amount of oil. Coastal water quality

would not only be impacted by the oil, gas, and their respective components but also to some degree from 

cleanup and mitigation efforts. Increased vessel traffic, hydromodification (e.g., dredging, berm building, 

boom deployment, etc.), and the addition of dispersants and methanol to the marine environment in an 

effort to contain, mitigate, or clean up the oil may also tax the environment to some degree.

Summary and Conclusion

Water quality in coastal waters would be impacted by sediment disturbance and suspension (i.e., 

turbidity), vessel discharges, erosion, runoff from nonpoint-source pollutants (including river inflows), 

seasonal influences, and accidental events. These impacts may be a result of a CPA proposed action and 

the OCS Program, State oil and gas activity, the activities of other Federal agencies (including the 

military), natural events or processes, or activities related to the direct or indirect use of land and 
Description of the Environment and Impact Analysis 4-21

waterways by the human population (e.g., urbanization, agricultural practices, coastal industry, and 

municipal wastes). The impacts resulting from a CPA proposed action are a small addition to the 

cumulative impacts on the coastal waters of the Gulf of Mexico because non-OCS activities, including 

vessel traffic, erosion, and nonpoint source runoff, are cumulatively responsible for a majority of coastal 

water impacts. Increased turbidity and discharge from a CPA proposed action would be temporary in 

nature and minimized by regulations and mitigation. Since a catastrophic OCS Program-related accident, 

though not reasonably foreseeable and not part of a CPA proposed action, would not be expected to occur 

in coastal waters, the impact of accidental spills is expected to be small. The incremental contribution of 

the routine activities and accidental events associated with a CPA proposed action to the cumulative 

impacts on coastal water quality is not expected to be significant for the reasons identified above.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

Various Internet sources were examined and literature searches conducted to assess the availability of 

new information regarding the water quality and sediment quality in coastal waters that may be pertinent 

to the CPA. The searches included, but were not limited to, Google, Google Scholar, several USEPA 

websites, the Gulf of Mexico Sea Grant Programs website, the Coastal Response Research at the 

University of New Hampshire website, and the NOAA Central Library Deepwater Horizon: A 

Preliminary Bibliography of Published Research and Expert Commentary website. The most recent 

coastal condition report (USEPA, 2012a), which evaluated the Gulf Coast from 2003 to 2006, found that 

the overall rating of the Gulf Coast was fair, which is a slight improvement from a previous rating of fair 

to poor, while the specific ratings for water quality, sediment quality, and the coastal habitat index 

remained fair, poor, and poor, respectively. Thus, there was not a significant change in the ratings that 

were reported in the 2012-2017 WPA/CPA Multisale EIS. The ratings reported do not demonstrate any 

analysis after the Deepwater Horizon explosion, spill, and response efforts. A Deepwater Horizon oil 

spill dataset, including extensive chemical analyses of sediment and water, is available online through 

NOAA (USDOC, NOAA, 2013a). The data set as a whole is not fully interpreted or discussed in context 

to the condition of the Gulf of Mexico, but since these data are the work of other Federal agencies, state 

environmental management agencies and BP and its contractors that has been compiled by NOAA, at 

least some of these data were discussed in the Inter-Agency Joint Analysis Group reports as well as the 

Operational Science Advisory Reports (OSAT) discussed in the 2012-2017 WPA/CPA Multisale EIS and 

incorporated by reference into the WPA 233/CPA 231 Supplemental EIS. BOEM expects these data to 

be considered by the scientific community, and further incorporated into additional reports and published 

in peer-reviewed literature in the future.

A recent study independently analyzed chemical data from the Deepwater Horizon explosion, oil 

spill, and response and derived an average environmental release rate for hydrocarbons of (10.1 ± 2.0) x 

106 kg/d during the Deepwater Horizon oil spill, which confirmed the official average leak rate of 

(10.2 ± 1.0) x 106 kg/d (Ryerson et al., 2011). Another study found that water-soluble petroleum 

compounds were found to dissolve into the water column to a greater degree than what is typically 

observed for surface spills (Reddy et al., 2011). Furthermore, the study indicated that the oil contained 

approximately 3.9 percent PAH’s by weight, which results in an estimated release of 2.1 x 1010 grams of 

PAH’s (Reddy et al., 2011; Reddy, official communication 2012). A study of coastal waters sampled for 

bioavailable PAH’s in Grand Isle, Louisiana; Gulfport, Mississippi; Gulf Shores, Alabama; and Gulf 

Breeze, Florida, was made using passive sampling devices. The study began sampling prior to any 

shoreline oiling on May 10, 2010, and continued for more than a year. After the oil spill, bioavailable 

PAH levels were statistically significantly higher than pre-spill levels; however, the PAH levels at all 

locations had returned to pre-spill levels by March 2011 (Allan et al., 2012). Elevated PAH 

concentrations were observed again at the Alabama sampling location in summer 2011. The authors of 

this study suggested that this increase may be due to resuspension of contaminated sediments or 

continued nearshore cleanup activities. Increased inputs from other sources and/or climatic factors could 

not be ruled out (Allan et al., 2012). This research confirms information that was extrapolated in the 

2012-2017 WPA/CPA Multisale EIS from then existing data on the Deepwater Horizon explosion and oil 

spill, namely that oil from a low-probability catastrophic event under pressure and with more soluble 

components may become entrained in the water column. As such, this new information has not altered 
4-22 Central Planning Area Lease Sales 235, 241, and 247 EIS

the conclusions from the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS.

Additional studies examining dispersant use have also been published. Rico-Martinez et al. (2013) 

found that toxicity testing with various species of marine rotifer revealed that, when COREXIT 9500A 

was well mixed with oil, the toxicity increased as much as 52 fold. Without mixing, the effect was 

decreased to 27.6 fold. The authors noted that the rotifer strain from the Gulf of Mexico was most 

tolerant to Macondo oil. Though the authors described the effect as synergistic, other authors have noted 

that the increased toxicity is actually due to the oil itself (Wu et al., 2012) as the dispersant helps the oil 

dissolve into the water phase and then become more available. Furthermore, Chakraborty et al. (2012) 

found that COREXIT 9500 was not toxic to indigenous microbes and that various components of the 

COREXIT 9500 were degraded. This is part of the ongoing debate that exists with the use of dispersants 

as a response tool. Dispersants help make the oil more bioavailable so that the oil is subject to increased 

degradation, including biodegradation; however, oil that is more bioavailable may also be more toxic to 

some species. Debates also exist within the spill modeling community as to whether the dispersants were 

effective at keeping the oil from the Deepwater Horizon oil spill submerged. Paris et al. (2012) 

concluded from their modeling efforts that dispersants only marginally decreased the amount of oil 

surfacing; however, a comment on that work by Adams et al. (2013) notes that the droplet size model 

used in the Paris et al. work was not appropriate for the conditions of the Deepwater Horizon explosion 

and oil spill. A discussion on the use of dispersants as a response tool is provided in the 2012-2017 

WPA/CPA Multisale EIS. As monitoring, experimental research, and modelling research continues to 

examine the fate of the oil, dispersants, and their components after the Deepwater Horizon explosion, oil 

spill, and response, the results of these different scientific approaches coupled together should improve 

our understanding of the use of dispersants deep under water.

A study by Gutierrez et al. (2013) explored the role of exopolysaccharides (EPS) in the fate of the oil 

released during the Deepwater Horizon oil spill. The study showed that the amphiphilic EPS produced by 

the strain of bacteria studied increased the solubilization of aromatic hydrocarbons and enhanced their 

biodegradation by an indigenous microbial community. The study found that the Gulf was enriched with 

bacteria that produced amphiphilic EPS and suggested that the enrichment of such bacteria likely 

contributed to the removal of oil as well as the formation of oil aggregates in surface waters. This study 

serves as a reminder that natural dispersion of oil takes place, as is noted in the 2012-2017 WPA/CPA 

Multisale EIS. In other words, if oil should be released into the Gulf of Mexico, some dispersion would 

be expected even if dispersants were not used in response efforts.

Additionally, some regulations have been updated and strengthened since the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The NPDES general permit for new and 

existing sources and new discharges in the offshore subcategory of the oil and gas extraction point source 

category for the western portion of the Gulf of Mexico OCS (GMG290000; USEPA Region 6) was 

reissued on October 10, 2012, and will expire on September 30, 2017 (USEPA, 2012b). On March 28, 

2013, USEPA reissued the Vessel General Permit (VGP) for another 5 years (USEPA, 2013a). The 

reissued permit, the 2013 VGP, superseded the 2008 VGP on December 19, 2013. The 2013 VGP 

continues to regulate 26 specific discharge categories that were contained in the 2008 VGP and is more 

stringent because the permit contains numeric ballast water discharge limits for most vessels and more 

stringent effluent limits for oil-to-sea interfaces and exhaust gas scrubber washwater (USEPA 2013b).

It is currently impossible to estimate precisely the long-term impacts that the spill from the 

Deepwater Horizon explosion will have on coastal water quality. Various monitoring efforts and 

environmental studies are underway. More time is needed to fully assess the impacts of the Deepwater 

Horizon explosion, oil spill, and response. Although response efforts decreased the fraction of oil 

remaining in Gulf waters and reduced the amount of oil contacting the coastline, oil still remains in the 

environment (USDOC, NOAA, 2011b and 2011c; OSAT-2, 2011). Oil from the Deepwater Horizon

explosion and resulting oil spill that appears to have been buried along the coast was unearthed by 

Hurricane Isaac and was reported to be discovered mostly as tarballs in several locations, including 

Elmer’s Island and Grand Isle, Louisiana, as well as possible locations along the Mississippi and Alabama 

coasts (Burdeau and Reeves, 2012). Testing at Louisiana State University also confirmed a match to oil 

resulting from the Deepwater Horizon explosion with samples collected from Barataria Bay and the Bay 

Jimmy area, as well as from the Fort Morgan area in Alabama (Overton, official communication, 2012). 

Nevertheless, this possibility of resuspended oils or remnants due to natural or anthropogenic causes was 

identified and discussed in the 2012-2017 WPA/CPA Multisale EIS and remains an ongoing concern.
Description of the Environment and Impact Analysis 4-23

There remains some incomplete or unavailable information that may be relevant to reasonably 

foreseeable impacts on coastal water quality. Much of this information relates to the Deepwater Horizon

explosion, oil spill, and response and is continuing to be collected and developed through the NRDA 

process. These research projects may be years from completion. Few conclusions have been released to 

the public to date, though as noted above extensive data sets have been released to the public. Some of 

these data have been discussed in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS as part of the discussion of published Federal government reports.

In light of this incomplete and unavailable information, BOEM’s subject-matter experts have used 

credible scientific information that is available and applied it using scientifically accepted methodology. 

Given the available data on sediments and water quality that have been released, as described above, 

BOEM believes that this incomplete or unavailable information is not essential to a reasoned choice 

among alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA Multisale EIS.

4.1.1.2.2. Offshore Waters

BOEM has reexamined the analysis for offshore water quality presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

offshore water quality presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 

247.

A detailed description of offshore waters and the full analyses of the potential impacts of routine 

activities and accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.2.2 

of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.2.2 of 

the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the 

cumulative impacts is presented below. The following information is a summary of the resource 

description incorporated from the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. New information that has become available since those documents were published is 

presented below.

Impacts on Routine and Accidental Events

The routine activities associated with a CPA proposed action that would impact water quality include 

the following: discharges during the drilling of exploration and development wells; structure installation 

and removal; discharges during production; installation of pipelines; workovers of wells; maintenance 

dredging of existing navigational canals; service-vessel discharges; and nonpoint-source runoff.

During exploratory activities, the primary impacting sources to offshore water quality are discharges

of drilling fluids and cuttings. During platform installation and removal activities, the primary impacting 

sources to water quality are sediment disturbance and temporarily increased turbidity. Impacting 

discharges during production activities are produced water and supply-vessel discharges. Regulations are 

in place to limit the toxicity of the discharge components, the levels of incidental contaminants in these 

discharges, and, in some cases, the discharge rates and discharge locations. Pipeline installation can also 

affect water quality by sediment disturbance and increased turbidity. Service-vessel discharges might 

include water with an oil concentration of approximately 15 ppm as established by regulatory standards. 

Any disturbance of the seafloor would increase turbidity in the surrounding water, but the increased 

turbidity should be temporary and restricted to the area near the disturbance. There are multiple Federal 

regulations and permit requirements that would decrease the magnitude of these activities. Impacts to 

offshore waters from routine activities associated with a CPA proposed action should be minimal as long 

as regulatory requirements are followed. A detailed impact analysis of the routine impacts of OCS 

activities associated with proposed CPA Lease Sales 235, 241, and 247 on offshore waters can be found 

in Chapter 4.2.1.2.2.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.2.2 of the WPA 233/CPA 231 Supplemental EIS.

Accidental events associated with a CPA proposed action that could impact offshore water quality

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

or drilling fluids, loss of well control, pipeline failures, collisions, or other malfunctions that would result 
4-24 Central Planning Area Lease Sales 235, 241, and 247 EIS

in such spills. Spills from collisions are not expected to be significant. Overall, since major losses of 

well control and blowouts are rare events, the potential impacts to offshore water quality are not expected 

to be significant except in the rare case of a low-probability catastrophic event. Although response efforts 

may decrease the amount of oil in the environment, the response efforts may also impact the environment 

through, for example, increased vessel traffic and the application of dispersants. Natural degradation 

processes will also decrease the amount of spilled oil over time. Chemicals used in the oil and gas 

industry are not a significant risk for a spill because they are either nontoxic, are used in minor quantities, 

or are only used on a noncontinuous basis. A detailed impact analysis of the accidental impacts that may 

be associated with proposed CPA Lease Sales 235, 241, and 247 on offshore waters can be found in 

Chapter 4.2.1.2.2.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.2.2 of the WPA 233/CPA 231 Supplemental EIS. Accidental spills as a result of a lowprobability catastrophic event are discussed in Appendix B of this Supplemental EIS.

Summary and Conclusion

BOEM has reexamined the analysis for offshore water quality presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for 

offshore water quality presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS, as these newly available studies confirmed earlier estimates of hydrocarbon releases 

and noted the overall return to pre-spill PAH concentrations thus far. Furthermore, efforts to better 

understand and prevent hypoxia are ongoing as are efforts to better understand the complex process of 

microbial degradation after the Deepwater Horizon oil spill. Dispersant studies continue to illustrate the 

ongoing debate on the use of dispersant as a remediation tool. Regulations relevant to the quality of 

offshore waters continue to be implemented and updated to more stringent standards. The analysis and 

potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated information in the 

WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

Activities in the cumulative scenario that could impact offshore water quality generally include the 

broad categories of a CPA proposed action and the OCS Program, alternative energy activities, alternate 

use programs for platforms, sand borrowing, the activities of other Federal agencies (including the 

military), natural events or processes, State oil and gas activity, and activities related to the direct or 

indirect use of land and waterways by the human population (e.g., urbanization, agricultural practices, 

coastal industry, and municipal wastes). Although some of these impacts are likely to affect coastal areas 

to a greater degree than offshore waters, coastal pollutants that are transported away from shore would 

also affect offshore environments. Many of these categories noted above would have some of the same 

specific impacts (e.g., vessel traffic would occur for all of these categories listed above except natural 

processes).

OCS Oil- and Gas-Related Impacts 

The OCS oil- and gas-related impacts include erosion and runoff, sediment disturbance and turbidity, 

vessel discharges, discharges from exploration and production activities, and accidental releases of oil, 

gas, or chemicals. Further discussion of these impacts is presented below.

Erosion and runoff from nonpoint sources degrade water quality. Nonpoint-source runoff from 

onshore support facilities could result from OCS oil- and gas-related activities; however, as discussed 

below, runoff from OCS activities is not the leading source of contaminant runoff. The leading source of 

contaminants that impair coastal water quality is urban runoff. Although offshore waters would not be 

affected as strongly as coastal waters since contaminants would be more diluted by the time they reached 

offshore areas, in many cases this runoff would still contribute somewhat to the degradation of offshore 

waters.

Sediment disturbance and turbidity may result from pipeline installation, platform installation and 

removal, and discharges of muds and cuttings from drilling operations. These impacts generally degrade 
Description of the Environment and Impact Analysis 4-25

water quality locally and are not expected to last for long time periods. Furthermore, discharges from 

drilling platforms are regulated by USEPA through the NPDES permit process; thus, effects from these 

discharges should be limited.

It should be noted that, since the marine environment is a dynamic system, sediment quality and 

water quality can affect each other. For example, a contaminant may react with the mineral particles in 

the sediment and be removed from the water column (e.g., adsorption). Thus, under appropriate 

conditions, sediments can serve as sinks for contaminants such as metals, nutrients, or organic 

compounds. However, if sediments are (re)suspended, the resuspension can lead to a temporary shift in 

water quality, including a localized and temporal release of any formally sorbed metals as well as nutrient 

recycling (Caetano et al., 2003; Fanning et al., 1982).

Vessel discharges can degrade water quality. Vessels may be service vessels supporting a CPA 

proposed action or OCS oil- and gas-related activities. Fortunately, for many types of vessels, most 

discharges are treated or otherwise managed prior to release through regulations administered by USCG 

and/or USEPA, and many regulations are becoming more stringent. The USCG Ballast Water 

Management Program became mandatory for some vessels in 2004 (33 CFR part 151 subparts C and D) 

(USDHS, CG, 2012b). The goal of the program was designed to prevent the introduction of 

nonindigenous (invasive) species that would affect local water quality. The USCG is amending its 

regulations on ballast water management by establishing a standard for the allowable concentration of 

living organisms in ballast water discharged from ships in waters of the U.S and by establishing an 

approval process for ballast water management systems. The final rule was published on March 23, 2012, 

in the Federal Register and became effective on June 21, 2012 (USDHS, CG, 2012b). The final VGP, 

issued by USEPA, became effective on December 19, 2008, and was an addition to already existing 

NPDES permit requirements. The permit increased the NPDES regulations so that discharges incidental 

to the normal operation of vessels operating as a means of transportation were no longer excluded unless 

exempted by Congressional legislation. On March 28, 2013, USEPA reissued the VGP for another 5 

years (USEPA, 2013a). The reissued permit, the 2013 VGP, superseded the 2008 VGP on December 19, 

2013. The 2013 VGP continues to regulate 26 specific discharge categories that were contained in the 

2008 VGP and is more stringent because the permit contains numeric ballast water discharge limits for 

most vessels and more stringent effluent limits for oil-to-sea interfaces and exhaust gas scrubber 

washwater (USEPA, 2013b). The draft sVGP, once finalized, will authorize discharges incidental to the 

normal operation of nonmilitary and nonrecreational vessels less than 79 ft (24 m) in length (USEPA, 

2011a). These regulations should minimize the cumulative impacts of vessel activities.

Discharges from exploration and production activities can degrade water quality in offshore waters. 

The USEPA regulates discharges associated with offshore oil and gas exploration, development, and 

production activities on the OCS under the Clean Water Act’s NPDES program. Regulated wastes

include drilling fluids, drill cuttings, deck drainage, produced water, produced sand, well treatment fluids, 

well completion fluids, well workover fluids, sanitary wastes, domestic wastes, and miscellaneous wastes 

(USEPA, 2012a). The bulk of waste materials produced by offshore oil and gas activities are produced 

water (formation water) and drilling muds and cuttings. Produced water is the largest waste stream by 

volume from the oil and gas industry that enters Gulf waters. The National Research Council has 

estimated the quantity of oil in produced water entering the Gulf per year to be 11,905 bbl of oil 

contributed from 473,000,000 bbl of produced water, with a resulting oil and grease discharge of 

approximately 11,905 bbl per year (NRC, 2003, Table D-8, page 200). However, produced water is 

commonly treated to separate free oil and, as noted above, it is a regulated discharge. Since discharges 

from drilling and production platforms are regulated by USEPA through the NPDES permit process, the 

effects from these discharges should be limited. Accidental releases of oil, gas, or chemicals would 

degrade water quality during and after the spill until either the spill is cleaned up or natural processes 

degrade or disperse the spill. These accidental releases could be a result of a CPA proposed action or 

ongoing OCS activity. Actions taking place directly in offshore waters would generally have more 

significant impacts on offshore waters. The impacts of low-probability catastrophic spills, though not 

reasonably foreseeable and not part of a CPA proposed action, are discussed in Appendix B. The extent 

of impact from a spill depends on the location of release and the behavior and fate of oil in the water 

column (e.g., the movement of oil and the rate and nature of weathering), which, in turn, depends on 

oceanographic and meteorological conditions at the time (Appendices A.2 and A.3 of the 2012-2017 

WPA/CPA Multisale EIS). Chapter 3.2 of this Supplemental EIS and Chapter 3.2 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS contain more information on 
4-26 Central Planning Area Lease Sales 235, 241, and 247 EIS

accidental releases. Accidental spills as a result of a low-probability catastrophic event are discussed in 

Appendix B of this Supplemental EIS.

A major hurricane can affect OCS activities and result in a greater number of spill events with 

increased spill volume and oil-spill-response times. In the case of an accidental event, it is likely that 

response efforts would reduce the amount of oil. (Refer to Chapter 3.2.1.9 of this Supplemental EIS and 

to Chapter 3.2.1.9 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS 

for further discussion of oil-spill-response considerations.) Offshore water quality would not only be 

impacted by the oil, gas, and their respective components but also to some degree from cleanup and 

mitigation efforts. Increased vessel traffic and the addition of dispersants and methanol to the marine 

environment in an effort to contain, mitigate, or clean up the oil may also tax the environment to some 

degree.

Non-OCS Oil- and Gas-Related Impacts

Activities not related to a CPA proposed action or the OCS Program that may impact offshore waters 

include State oil and gas activities, alternative uses of platforms (e.g., aquaculture), sand borrowing, 

renewable energy activities, the activities of other Federal agencies (including the military), natural events 

or processes, and activities related to the direct or indirect use of land and waterways by the human

population. These activities may result in erosion and runoff, sediment disturbance and turbidity, vessel 

discharges, natural releases of oil and gas (e.g., seeps), and accidental releases of oil, gas, or chemicals. 

Further discussion of these impacts is presented below.

Erosion and runoff from point and nonpoint sources degrade water quality. Nonpoint-source runoff 

from onshore support facilities could result from State oil and gas activities, other industries, and coastal 

development, as well as OCS oil- and gas-related activities. The leading source of contaminants that 

impair coastal water quality is urban runoff. Although offshore waters would not be affected as strongly 

as coastal waters since contaminants would be more diluted by the time they reached offshore areas, in 

many cases this runoff would still contribute somewhat to the degradation of offshore waters. Urban 

runoff can include suspended solids, heavy metals and pesticides, oil and grease, nutrients, and organic 

matter. Urban runoff increases with population growth, and the Gulf Coast region has experienced a 109 

percent population growth since 1970, with an additional expected 15 percent increase by 2020 (USDOC, 

NOAA, 2011a). The National Research Council (2003, Table I-4, page 237) estimated that, on average, 

approximately 26,324 bbl of oil per year entered Gulf waters from petrochemical and oil refinery 

industries in Louisiana and Texas. Chapter 3.1.1.7 of this Supplemental EIS and Chapter 3.1.1.7 of the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS discuss the various 

sources of petroleum hydrocarbons that can enter the Gulf of Mexico in further detail. The natural 

emptying of rivers into the GOM as part of the water cycle may introduce chemical and physical factors 

that alter the condition of the receiving waters. The Mississippi River introduced approximately 

3,680,938 bbl of oil and grease per year from land-based sources (NRC, 2003, Table I-9, page 242) into 

the waters of the Gulf. Nutrients carried in waters of the Mississippi River contribute to seasonal 

formation of the hypoxic zone on the Louisiana-Texas shelf. The zone of hypoxia on the LouisianaTexas shelf is the largest zone in the United States and the entire western Atlantic Ocean (Turner et al., 

2005; Figure 4-3 in the 2012-2017 WPA/CPA Multisale EIS). 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. The formation of the hypoxic zone is attributed to a 

combination of riverborne nutrient inputs supporting phytoplankton growth and shelf stratification, which 

limit the aeration of bottom waters. The areal extent of mid-summer hypoxia has ranged from 40 to 

22,000 km2 (15 to 8,494 mi2

) and has averaged approximately 13,500 km2 (5,212 mi2) during 1985-2007 

(Greene et al., 2009). The hypoxic conditions last until local wind-driven circulation mixes the water 

again. The USEPA has regulatory programs designed to protect the waters that enter the Gulf, including 

the regulation of point-source discharges. If these and other water quality programs and regulations 

continue to be administered and enforced, it is not expected that additional oil and gas activities would 

adversely impact the overall water quality of the region.

Sediment disturbance and turbidity in State waters may result from pipeline installation, platform 

installation and removal, discharges of muds and cuttings from drilling operations, disposal of dredge 

materials, sand borrowing, sediment deposition from rivers, and hurricanes. Turbidity is also influenced 

by the season. These impacts may be the result of other Federal agencies (including the military) or 
Description of the Environment and Impact Analysis 4-27

natural processes. State oil and gas activities may have some effect if they take place near offshore 

waters. Dredging projects related to restoration or flood prevention measures may be directed by the 

Federal Government for the benefit of growing coastal populations. These impacts generally degrade 

water quality locally and are not expected to last for long time periods. Furthermore, discharges from 

drilling platforms are regulated by USEPA through the NPDES permit process, including USEPAauthorized State programs; thus, effects from these discharges should be limited.

Vessel discharges can degrade water quality. Vessels may be service vessels supporting State oil and 

gas activities. However, the vessels may also be vessels used for shipping, fishing, military activities, or 

recreational boating. State oil and gas activities, fishing, and recreational boating would have fewer 

effects on offshore waters except for larger fishing operations and cruise lines, as smaller vessels tend to 

remain near shore. Fortunately, for many types of vessels, most discharges are treated or otherwise 

managed prior to release through regulations administered by USCG and/or USEPA, and many 

regulations such as the USCG Ballast Water Management Program and the USEPA VGP and sVGP are 

becoming more stringent as discussed in further detail above. A Congressional moratorium exempted all 

incidental discharges, with the exception of ballast water, from commercial fishing vessels and 

nonrecreational, nonmilitary vessels less than 79 ft (24 m) in length, but the moratorium expired on 

December 18, 2013. The sVGP will provide coverage for those vessels (USEPA, 2011a) once finalized. 

These regulations should minimize the cumulative impacts of vessel activities.

Accidental releases of oil, gas, or chemicals would degrade water quality during and after the spill 

until either the spill is cleaned up or natural processes degrade or disperse the spill. These accidental 

releases could be a result of State oil and gas activity, the transport of commodities to ports, and/or coastal 

industries. Actions taking place directly in offshore waters would generally have more significant 

impacts on offshore waters. The extent of impact from a spill depends on the release location and the 

behavior and fate of oil in the water column (e.g., the movement of oil and the rate and nature of 

weathering), which, in turn, depends on oceanographic and meteorological conditions at the time.

A major hurricane can affect State oil and gas activities and result in a greater number of spill events 

with increased spill volume and oil-spill-response times. In the case of an accidental event, it is likely 

that response efforts would reduce the amount of oil. (Refer to Chapter 3.2.1.9 of this Supplemental EIS 

and to Chapter 3.2.1.9 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS for further discussion of oil-spill-response considerations.) Offshore water quality would not only be 

impacted by the oil, gas, and their respective components but also to some degree from cleanup and 

mitigation efforts. Increased vessel traffic and the addition of dispersants and methanol to the marine 

environment in an effort to contain, mitigate, or clean up the oil may also tax the environment to some 

degree.

Offshore waters, especially deeper waters, are more directly affected by natural seeps since the 

natural seeps in the Gulf of Mexico are located in offshore waters. Natural seeps are the result of natural 

processes. Hydrocarbons enter the Gulf of Mexico through natural seeps at a rate of approximately 

980,392 bbl/year (a range of approximately 560,224-1,400,560 bbl/year) (NRC, 2003, page 191). 

Hydrocarbons from natural seeps are considered to be the highest contributor of petroleum hydrocarbons 

to the marine environment (NRC, 2003, page 33). However, studies have shown that benthic 

communities are often acclimated to these seeps and may even utilize them to some degree (NRC, 2003, 

references therein and page 33).

Summary and Conclusion

Water quality in offshore waters may be impacted by sediment disturbance and suspension (i.e., 

turbidity), vessel discharges, erosion and runoff of nonpoint-source pollutants (including river inflows), 

natural seeps, discharges from exploration and production activities, and accidental events. These 

impacts may be a result of a CPA proposed action and the OCS Program, the activities of other Federal 

agencies (including the military), private vessels, and natural events or processes. To a lesser degree, 

these impacts may also be a result of State oil and gas activity or activities or related to the direct or 

indirect use of land and waterways by the human population (e.g., urbanization, agricultural practices, 

coastal industry, and municipal wastes). Routine activities that increase turbidity and discharges are 

temporary in nature and are regulated; therefore, these activities would not have a lasting adverse impact 

on water quality. In the case of a large-scale spill event, degradation processes in both surface and 

subsurface waters would decrease the amount of spilled oil over time through natural processes that can 
4-28 Central Planning Area Lease Sales 235, 241, and 247 EIS

physically, chemically, and biologically degrade oil. The impacts resulting from a CPA proposed action 

are a small addition to the cumulative impacts on the offshore waters of the Gulf when compared with 

inputs from natural hydrocarbon inputs (seeps), coastal factors (such as erosion and runoff), and other 

non-OCS industrial discharges. The incremental contribution of the routine activities and accidental 

discharges associated with a CPA proposed action to the cumulative impacts on offshore water quality is 

not expected to be significant.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

Various Internet sources were examined and literature searches conducted in order to assess recent 

information regarding the water quality and sediment quality in offshore waters that may be pertinent to 

the CPA. The searches included, but were not limited to, Google, Google Scholar, several USEPA 

websites, the Gulf of Mexico Sea Grant Programs website, the Coastal Response Research at the 

University of New Hampshire website, and the NOAA Central Library Deepwater Horizon: A 

Preliminary Bibliography of Published Research and Expert Commentary website. The searches revealed 

the release of a Deepwater Horizon Oil Spill dataset, including extensive chemical analyses of sediment 

and water, which is available online through NOAA (USDOC, NOAA, 2013a). The data set as a whole is 

not fully interpreted or discussed in context to the condition of the Gulf of Mexico, but since these data 

are the work of other Federal agencies, State environmental management agencies, and BP and its 

contractors that has been compiled by NOAA, at least some of these data were discussed in the InterAgency Joint Analysis Group reports as well as the Operational Science Advisory Reports (OSAT) 

discussed in the 2012-2017 WPA/CPA Multisale EIS and incorporated by reference into the WPA 

233/CPA 231 Supplemental EIS. BOEM expects these data to be considered by the scientific community 

and further incorporated into additional reports and published in peer-reviewed literature in the future. A 

recent study independently analyzed chemical data from the Deepwater Horizon explosion, oil spill, and 

response and derived an average environmental release rate for hydrocarbons of (10.1± 2.0) x 106 kg/d 

during the Deepwater Horizon oil spill, which confirmed the official average leak rate of (10.2 ± 1.0) x 

106 kg/d (Ryerson et al., 2011). Another study found that water-soluble petroleum compounds were 

found to dissolve into the water column to a greater degree than what is typically observed for surface 

spills (Reddy et al., 2011). Furthermore, the study indicated that the oil contained approximately 3.9 

percent PAH’s by weight, which results in an estimated release of 2.1 x 1010 grams of PAH’s (Reddy et 

al., 2011; Reddy, official communication, 2012). Another study examined surface sediment samples from 

two locations 2 km and 6 km (1 mi and 4 mi) from the Macondo wellhead (Liu et al., 2012). The limited 

number of samples examined in the study found that the concentrations of total n-alkanes were two orders 

of magnitude higher and that total PAH’s were approximately three times higher at the station closer to 

the wellhead 1 year after the spill. The study observed clear signs of biodegradation; however, 

biodegradation in the sediments appears to be slow due to the presence of n-alkanes 1 year after the spill 

as well as the presence of benzene, ethylbenzene, toluene, and xylene (BTEX) and C3-benzenes (Liu et 

al., 2012). The weathering rate in the sediments appeared to be greater at the station farthest from the 

well. The authors attributed the weathering in the sediments to biodegradation and dissolution, and they 

suspected that the slow weathering may be due to low temperatures, low oxygen concentration, and less 

microbial activity (Liu et al., 2012). However, sorption of oil components onto sediment mineral or 

organic matter components may also slow the weathering of the oil as oil components associated with the 

sediment (solid phase) are generally considered less available than oil components associated with the 

water column (aqueous phase). This research confirms information that was extrapolated in the 2012-

2017 WPA/CPA Multisale EIS from then existing data on the Deepwater Horizon explosion, namely that 

oil from a low-probability catastrophic event under pressure and with more soluble components may 

become entrained in the water column or associated with the sediment. As such, this new information has 

not altered the conclusions from the 2012-2017 WPA/CPA Multisale EIS or WPA 233/CPA 231 

Supplemental EIS.

Studies continue to strive to better understand microbial degradation of hydrocarbons during the 

Deepwater Horizon oil spill. Dubinsky et al. (2013) challenged earlier work by Valentine et al. (2012) 

that suggested that respiratory succession and circulation patterns were responsible for the succession of 

bacterial communities that dominated the reported plume from the Deepwater Horizon oil spill. 

Dubinsky et al. (2013) concluded that multiple hydrocarbon-degrading bacteria operated concurrently 
Description of the Environment and Impact Analysis 4-29

during the spill, but their relative significance was controlled by changes in hydrocarbon supply, 

particularly after well intervention measures began. Regardless of the debate of the details regarding 

microbial remediation, both studies point to the efficiency of microbial degradation of hydrocarbons and 

thus do not change the conclusions of the 2012-2017 WPA/CPA Multisale EIS or WPA 233/CPA 231 

Supplemental EIS.

Additional studies were released that focused on dispersants. Rico-Martinez et al. (2013) found that 

toxicity testing with various species of marine rotifer revealed that, when COREXIT 9500A was well 

mixed with oil, the toxicity increased as much as 52 fold. Without mixing, the effect was decreased to 

27.6 fold. The authors noted that the rotifer strain from the Gulf of Mexico was most tolerant to Macondo

oil. Though the authors described the effect as synergistic, other authors have noted that the increased

toxicity is actually due to the oil itself (Wu et al., 2012a) as the dispersant helps the oil dissolve into the 

water phase and then become more available. Furthermore, Chakraborty et al. (2012) found that 

COREXIT 9500 was not toxic to indigenous microbes and that various components of the COREXIT 

9500 were degraded. This is part of the ongoing debate that exists with the use of dispersants as a 

response tool. Dispersants help make the oil more bioavailable so that the oil is subject to increased 

degradation, including biodegradation; however, more bioavailable oil may also be more toxic to some 

species.

Debates also exist within the spill modeling community as to whether the dispersants were effective 

at keeping the oil from the Deepwater Horizon oil spill submerged. Paris et al. (2012) concluded from 

their modeling efforts that dispersants only marginally decreased the amount of oil surfacing; however, a 

comment on that work by Adams et al. (2013) notes that the droplet size model used in the Paris et al. 

work was not appropriate for the conditions of the Deepwater Horizon explosion and oil spill. A 

discussion on the use of dispersants as a response tool is provided in the 2012-2017 WPA/CPA Multisale 

EIS. As monitoring, experimental research, and modelling research continues to examine the fate of the 

oil, dispersants, and their components after the Deepwater Horizon explosion, oil spill, and response, the 

results of these different scientific approaches coupled together should improve our understanding of the 

use of dispersants deep under water.

A study by Gutierrez et al. (2013) explored the role of exopolysaccharides (EPS) in the fate of the oil 

released during the Deepwater Horizon oil spill. The study showed that the amphiphilic EPS produced by 

the strain of bacteria studied increased the solubilization of aromatic hydrocarbons and enhanced their 

biodegradation by an indigenous microbial community. The study found that the Gulf was enriched with 

bacteria that produced amphiphilic EPS and suggested that the enrichment of such bacteria likely 

contributed to the removal of oil as well as the formation of oil aggregates in surface waters. This study 

serves as a reminder that natural dispersion of oil takes place, as is noted in the 2012-2017 WPA/CPA 

Multisale EIS. In other words, if oil should be released into the Gulf of Mexico, some dispersion would 

be expected even if dispersants were not used in response efforts.

Other new items relevant to the CPA include the latest data on the hypoxic zone in the northern 

GOM. The zone of hypoxia in the GOM on the Louisiana-Texas shelf was reported to be 5,800 mi2

(15,022 km2

) in 2013, which is above average (USDOC, NOAA, 2013b). Scientists thought the dead 

zone would be even larger based on modeling results, but mixed conditions and winds from the west 

reduced the area from the predicted amount.

Additionally, some regulations have been updated and strengthened since the 2012-2017 WPA/CPA 

Multisale EIS and the WPA 233/CPA 231 Supplemental EIS. The NPDES general permit for new and 

existing sources and new discharges in the offshore subcategory of the oil and gas extraction point source 

category for the western portion of the Gulf of Mexico OCS (GMG290000; USEPA Region 6) was 

reissued on October 10, 2012, and it will expire on September 30, 2017. On March 28, 2013, USEPA 

reissued the VGP for another 5 years (USEPA, 2013a). The reissued permit, the 2013 VGP, superseded 

the 2008 VGP on December 19, 2013. The 2013 VGP continues to regulate 26 specific discharge 

categories that were contained in the 2008 VGP and is more stringent because the permit contains 

numeric ballast water discharge limits for most vessels and more stringent effluent limits for oil-to-sea 

interfaces and exhaust gas scrubber washwater (USEPA 2013b).

As identified in the resource analyses in this Supplemental EIS, the 2012-2017 WPA/CPA Multisale 

EIS, and WPA 233/CPA 231 Supplemental EIS, incomplete or unavailable information regarding 

offshore water quality in the WPA may be relevant to reasonably foreseeable significant adverse effects. 

BOEM has determined that the information is not essential to a reasoned choice among alternatives.
4-30 Central Planning Area Lease Sales 235, 241, and 247 EIS

4.1.1.3. Coastal Barrier Beaches and Associated Dunes

BOEM has reexamined the analysis for coastal barrier beaches and associated dunes presented in the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional 

information presented below. No new significant information was discovered that would alter the impact 

conclusion for coastal barrier beaches and associated dunes presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

A detailed description of coastal barrier beaches and associated dunes and the full analyses of the 

potential impacts of routine activities and accidental events associated with a CPA proposed action are 

presented in Chapter 4.2.1.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental 

contribution to the cumulative impacts is presented below. The following information is a summary of 

the resource description incorporated from the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 

231 Supplemental EIS. Any new information that has become available since those documents were 

published is presented below.

Impacts of Routine and Accidental Events

The potential routine-impact producing factors on coastal barrier beaches and associated dunes of the 

CPA include pipeline emplacements, use of navigation channels by vessel traffic, dredging, and the use 

and construction of support infrastructure. A detailed impact analysis of the routine impacts of OCS 

activities associated with a CPA proposed action on coastal barrier beaches and associated dunes can be 

found in Chapter 4.2.1.3.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.3 of the WPA 233/CPA 231 Supplemental EIS.

Effects to coastal barrier beaches and associated dunes from pipeline emplacements, navigation 

channel use and dredging, and construction or continued use of infrastructure in support of a CPA 

proposed action are expected to be restricted to temporary and localized disturbances. The 0-1 pipeline 

landfalls projected in support of a CPA proposed action are not expected to cause significant impacts to 

barrier beaches because of the use of nonintrusive installation methods and regulations. Impacts could be 

reduced or eliminated through modern techniques such as horizontal, directional (trenchless) drilling to 

avoid damages to these sensitive wetland habitats. Any new processing facilities would not be expected 

to be constructed on barrier beaches.

Maintenance dredging of barrier inlets and bar channels is expected to occur, which, when combined 

with channel jetties, generally causes minor and localized impacts on adjacent barrier beaches downdrift 

of the channel. Updated navigational channels that support the OCS Program are listed in Table 3-10. 

Dredging activities in these channels are permitted, regulated, and coordinated by COE with the 

appropriate State and Federal resource agencies. Impacts from these operations are minimal due to 

requirements for the beneficial use of the dredged material for wetland and beach construction and 

restoration. Permit requirements further mitigate dredged material placement in approved disposal areas 

by requiring the dredged material to be placed in such a manner that it neither disrupts hydrology nor 

changes elevation in the surrounding marsh. Because these impacts occur whether a CPA proposed 

action is implemented or not, a CPA proposed action would account for a small percentage of these 

impacts.

Routine activities associated with a CPA proposed action are not expected to adversely alter barrier 

beach configurations much beyond existing, ongoing impacts in localized areas downdrift of artificially 

jettied and maintained channels. Strategic placement of dredged material from channel maintenance, 

channel deepening, and related actions can mitigate adverse impacts upon those localized areas.

Accidental disturbances resulting from a CPA proposed action, including oil spills and blowouts, 

have the potential to impact coastal barrier beaches and associated dunes of the CPA. A detailed impact 

analysis of the accidental impacts that may be associated with proposed CPA Lease Sales 235, 241, and 

247 on coastal barrier beaches and associated dunes can be found in Chapter 4.2.1.3.3 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.3 of the WPA 233/CPA 

231 Supplemental EIS.

The main accidental impact-producing factors that would affect coastal barrier beaches and associated 

dunes are oil spills and cleanup activities. Accidental spills as a result of a low-probability catastrophic 

event are discussed in Appendix B. 
Description of the Environment and Impact Analysis 4-31

Due to the proximity of inshore spills to barrier islands and beaches, inshore spills pose the greatest 

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

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

habitats. Such spills may result from either vessel collisions that release fuel and lubricants or from 

pipelines that rupture. Impacts of a nearshore spill would likely be considered short term in duration and 

minor in scope because the size of such a spill is projected to be small. When limited to just oil- and gasrelated spill sources such as platforms, pipelines, MODU’s, and support vessels, Louisiana, Texas, 

Mississippi, and Alabama will be expected to have a total of 130-170, 5-10, 3-5, and about 2 spills <1,000 

bbl/yr, respectively. Louisiana and Texas are the states most likely to have a spill ≥1,000 bbl occur in 

coastal waters (refer to Chapter 3.2.1.7.1 of the 2012-2017 WPA/CPA Multisale EIS). For offshore 

spills, oil would likely be lessened in toxicity when it reaches the coastal environments due to the distance 

from shore, increased weathering, and the possible use of dispersant. Equipment and personnel used in 

cleanup efforts can generate the greatest direct impacts to an area, such as the disturbance of beach and 

foredune sands through foot traffic and 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. Close monitoring and restrictions on the use of bottom-disturbing equipment would be 

needed to avoid or minimize those impacts.

Currently available information suggests that impacts on barrier islands and beaches from accidental 

impacts associated with a CPA proposed action would be minimal. Should a spill other than a lowprobability catastrophic spill contact a barrier beach, oiling is expected to be light and sand removal 

during cleanup activities minimized. No significant long-term impacts to the physical shape and structure 

of barrier beaches and associated dunes are expected to occur as a result of a CPA proposed action. A 

CPA proposed action would not pose a significant increase in risk to barrier island or beach resources.

Summary and Conclusion

BOEM has reexamined the analysis for coastal barrier beaches and associated dunes presented in the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional 

information presented above. No new significant information was discovered that would alter the impact 

conclusions with respect to routine and accidental activities for coastal barrier beaches and associated 

dunes presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. 

The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

This cumulative analysis considers the effects of impact-producing factors related to a CPA proposed 

action, prior and future OCS sales in the Gulf of Mexico, State oil and gas activities, other governmental 

and private projects and activities, and pertinent natural processes that may affect barrier beaches and 

dunes. 

Coastal barrier beaches and associated dunes are vulnerable to many impact-producing factors from 

both OCS oil- and gas-related impacts and non-OCS oil- and gas-related impacts. Specific OCS oil- and 

gas-related, impact-producing factors considered in this cumulative analysis include dredging, pipeline 

emplacement/landfalls, vessel traffic, oil spills, and oil-spill response and cleanup activities. Non-OCS 

oil- and gas-related activities considered include vessel traffic, river channelization, sediment deprivation, 

tropical and extra-tropical storm activity, sea-level rise, rapid submergence, and recreational use and 

tourism. 

River channelization, sediment deprivation, tropical and extra-tropical storm activity, sea-level rise, 

and rapid submergence have resulted in severe and rapid erosion of most of the barrier and shoreline 

landforms along the coastal areas of the CPA. Coastal barrier beaches have experienced severe adverse 

cumulative impacts from natural processes and human activities. Human activities that have caused the 

greatest adverse impacts are river channelization and damming, pipeline canals, navigation channel 

stabilization and maintenance, and beach stabilization structures. Deterioration of Gulf barrier beaches 

from these factors is expected to continue in the future. Federal, State, and local governments have made 

efforts over the last 10-20 years to slow the landward retreat of shorelines. Frequent intense storms, a 
4-32 Central Planning Area Lease Sales 235, 241, and 247 EIS

relative rise in sea level, and a deficit in the sediment budget (both of which are partly caused by manmade alterations of the environment) are the principal natural causes of barrier island landloss. Other 

non-OCS oil- and gas-related impacts include development and urbanization, tourism, and recreational 

activities. In addition, oil spills and oil-spill response and cleanup activities can originate from non-OCS

oil- and gas-related activities. While each of these factors can cause negative impacts to barrier beaches 

and associated dunes, a CPA proposed action would not greatly increase the overall impacts.

OCS Oil- and Gas-Related Impacts 

Navigation Channels, Vessel Traffic, and Pipeline Emplacements 

Continued navigation channel use and dredging, pipeline emplacements, and construction or 

continued use of infrastructure in support of a CPA proposed action could impact coastal habitats. The 

effects to coastal barrier beaches and associated dunes from pipeline emplacements, navigation channel 

use and dredging, and the construction or continued use of infrastructure in support of a CPA proposed 

action are expected to be restricted to temporary and localized disturbances. The estimated 0-1 pipeline 

landfalls projected in support of a CPA proposed action are not expected to cause significant impacts to 

barrier beaches because of the use of nonintrusive installation methods such as directional boring. The 

estimated 0-1 gas processing facilities would not be expected to be constructed on barrier beaches. The 

use of some existing facilities in support of a CPA proposed action and subsequent CPA proposed lease 

sales may extend the useful lives of those facilities. During that extended life, erosion-control structures 

may be installed to protect a facility. Although these measures may initially protect the facility as 

intended, such structures may accelerate erosion elsewhere in the vicinity. They may also cause the 

accumulation of sediments updrift of the structures; these sediments otherwise might have alleviated 

erosion downdrift of the structure. These induced erosion impacts would be most damaging locally. 

However, these efforts would most probably be small in scale within the coastal areas of the CPA. 

Therefore, effects from these activities are expected to be restricted to temporary and localized 

disturbances.

Maintenance dredging of barrier inlets and bar channels is expected to occur, which when combined 

with channel jetties generally causes impacts on adjacent barrier beaches downdrift of the channel due to 

sediment deprivation. These impacts would occur whether a CPA proposed action is implemented or not. 

With the established importance of barrier islands as frontline protection for both coastal wetlands and 

mainland infrastructure, there are no current or future plans for routing any new navigation channels 

through barrier islands. A CPA proposed action is estimated to account for less than 1 percent of the 

service-vessel traffic in the OCS.

A large temporary increase in vessel traffic in the CPA resulted from the Deepwater Horizon

explosion, oil spill, and response. Large numbers of specialty firefighting, dispersant, and skimmer 

vessels were concentrated around the Louisiana, Mississippi, and Alabama coasts. Support vessels for 

berm construction (skimmers, tugboats, sand barges, and dredges) and boom deployment comprised the 

bulk of the vessel traffic that was in close proximity to barrier islands. Due to the distance from the 

barrier islands and slow speed of these vessels, it is unlikely these vessels markedly increased erosion 

rates of these islands. In the short term, these vessels and dredges have the potential to resuspend oiled 

bottom sediments that may exist in the area of these islands or mainland shorelines. However, it is 

doubtful that cumulative erosion that results from increased vessel traffic related to catastrophic spills

would occur because the probability of catastrophic spills is low. This being the case, there should not be 

a sustained cumulative increase in the need for supply and support vessels. This is because vessel traffic 

would either decrease or reach a state of equilibrium to meet the needs of the working wells.

Oil Spills

Due to the proximity of inshore spills to barrier islands and beaches, inshore spills pose the greatest 

threat. Aging pipelines and infrastructure continue to be problematic, and the potential for spills could 

exist until they are replaced. Improperly abandoned wells can also have a potential to create spills, 

especially in the shallow State waters. The number and most probable spill sizes to occur in coastal 

waters in the future are expected to resemble the patterns that have occurred in the past, and the majority 

of inshore spills are assumed to be small in scale and short in duration; therefore, impacts would be 

minor. Oil from most offshore spills, including a low-probability catastrophic spill (more detail in 
Description of the Environment and Impact Analysis 4-33

Appendix B), is assumed 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 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 to 

ensure the least amount of disturbance to the areas.

Hurricanes and tropical storms will continue to erode and lower elevations of the barrier islands and 

to reduce their effectiveness as protection from inland oiling. While the probability of a catastrophic spill 

like the Deepwater Horizon oil spill is low and not reasonably expected, it cannot be entirely ruled out. 

Regardless of the spill size, some barrier islands could be oiled. Cleanup of these oiled islands and 

mainland beaches may involve utilizing heavy machinery that further impacts beach and littoral habitats. 

Based on the current analysis associated with the Deepwater Horizon spill, oil from offshore spills can 

lose many of its volatile and toxic components prior to onshore contact, which would render the residual 

beached oil low in PAH’s and other toxic compounds (OSAT-2, 2011). The form of the residual oil (i.e., 

tarballs, supratidal buried oil, or surf zone submerged oil mats) could affect its rate of weathering and 

biodegradation. Some oil may penetrate to depths beneath the reach of the cleanup methods. The 

remaining oil would persist in beach sands, periodically being released when storms and high tides 

resuspend or flush through beach sediments. Long-term stressors, including physical effects and the 

chemical toxicity of hydrocarbons, could lead to decreased primary production, plant dieback, and further 

erosion (Ko and Day, 2004a); although at some point the impact of cleanup operations exceeds the impact 

of the remaining oil (OSAT 2010). The OSAT-2 report (2011) found an 86-98 percent depletion of 

PAH’s in the weathered samples that were beached. The buried supratidal samples underwent less 

biodegradation due to lack of oxygen, but they were estimated to decrease to 20 percent of current levels 

within 5 years (OSAT-2, 2011). The weathered oils measured in the beach sediment did not surpass any 

USEPA exceedances for aquatic wildlife, and the National Environmental Benefits Analysis performed 

by OSAT (2010) determined that the residual oil remaining after cleanup efforts would be less damaging 

to the habitat and associated resources than continuing the cleanup effort.

The State of Louisiana constructed barrier sand berms along the beaches of barrier islands in an 

attempt to keep the oil from reaching the coast. Such measures can impact barrier islands through 

increasing compaction, altering currents, and removing sand supplies needed for natural barrier island 

formation. These berms resulted in changes to the ecosystems they were intended to protect (Martinez, 

et al., 2011).

The barrier beaches of Deltaic Louisiana have the greatest rates of erosion and landward retreat of 

any known in the Western Hemisphere and are among the greatest rates on earth. Long-term impacts to 

contacted beaches from these spills could occur if significant volumes of sand were removed during 

cleanup operations. Removing sand from the coastal littoral environment, particularly in the sand-starved 

transgressive setting of coastal Louisiana, could result in accelerated coastal erosion. Spill cleanup is 

difficult in the inaccessible setting of coastal Louisiana. This analysis assumes that Louisiana would 

require the responsible party to clean the beach without removing significant volumes of sand or to 

replace the sand removed. Hence, cleanup operations are not expected to cause permanent effects on 

barrier beach stability. Within a few months, adjustments in beach configuration may result from the 

disturbance and movement of sand during cleanup. Mechanized cleanup was used in Alabama and 

Florida to remove tarballs from recreational beaches. While substantial amounts of sand were not 

removed, but sifted in place to remove tarballs, it is too soon to determine if there will be long-term 

effects on specific interstitial organisms that live in the sands of the beach face.

The reduction in slope on the beach face, loss of dune elevation, and development of scour inlets 

resulting from past hurricane activity contribute to future vulnerability to oil spills of the once-protected 

coastal inland habitats. The barrier and mainland beaches will continue to be susceptible to spills

associated with vessel collisions, pipeline breaks, and refinery accidents near or at transfer facilities by 

the ports of Houston and Beaumont. Hurricane Ike resulted in numerous oil spills along the Texas coast. 

Future spills that would affect these areas are possible as refinery and offshore production facilities and 

pipelines continue to age and become more vulnerable to storm and hurricane damage.

Most of the Gulf Coast is comprised of sandy beaches with little vegetation directly on the beach 

head, except in parts of Louisiana. The more vulnerable wetland vegetation is located behind the dune or 

beach systems where it is less likely to come in contact with spilled oil from the OCS. Beach cleanup 

techniques involving heavy machinery can drive oil farther into the sediment; however, new machinery 

allows the sand to be sifted in place and returned to the beach after the oil is removed. Some oil may 
4-34 Central Planning Area Lease Sales 235, 241, and 247 EIS

penetrate to depths beneath the reach of the cleanup methods. The remaining oil would persist in beach 

sands, periodically being released when storms and high tides resuspend or flush through beach 

sediments. 

Non-OCS Oil- and Gas-Related Impacts

Vessel Traffic

Maintenance dredging of barrier inlets and bar channels is expected to occur, which when combined 

with channel jetties generally causes impacts on adjacent barrier beaches downdrift of the channel due to 

sediment deprivation. These impacts would occur from necessary channel maintenance to accommodate 

non-OCS vessel traffic. More than 98 percent of total vessel traffic is not associated with a CPA 

proposed action. With the established importance of barrier islands as frontline protection for both 

coastal wetlands and mainland infrastructure, there are no current or future plans for routing any new 

navigation channels through barrier islands.

Oil Spills

Non-OCS 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. Coastal or inland spills have the potential to have greater effects on beaches and dunes

because the oil would not have the chance to weather and degrade before reaching the resource. Effects 

of non-OCS oil- and gas-related spills would be similar to OCS oil- and gas-related spills.

River Channelization and Beach Protection 

Over the course of geological history since the peak of the last ice age 18,000 years ago, the barrier 

islands have migrated toward the present coast. The Gulf-facing coasts of the barrier islands have been 

eroded by the steady rise in sea level. Historically, as the Gulf’s coast retreated, the landward side of the 

islands has extended and has been built up by sand deposits from over wash during storms. The vegetated 

dunes prevent some degree of sediment transport to the back side of the dune and increase the potential 

for erosion due to wash back on the dune face, and as a result, the islands are getting narrower.

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 Gulf. These changes may result in the opening 

and deepening of many new tidal channels that connect to the Gulf and inland waterbodies. These 

incremental changes would cause adverse impacts to barrier beaches and dunes. Efforts to stabilize the 

Gulf shoreline have adversely impacted barrier landscapes in Louisiana and Texas. Large numbers and 

varieties of stabilization techniques, such as groins, jetties, and seawalls, as well as artificially maintained 

channels and jetties, installed to stabilize navigation channels, have been applied along the Gulf Coast. 

These efforts have contributed to coastal erosion by depriving downdrift beaches of sediments, which 

accelerates erosion there, 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.

Other Anthropogenic and Natural Processes 

Adverse effects on barrier beaches and dunes have resulted from changes to the natural dynamics of 

water and sediment flow along the coast. Some of these changes can be attributed to man-made 

alterations to the environment. This can happen in an attempt to control catastrophic floods and change 

the natural environment to better accommodate navigation on waterways used to support OCS and nonOCS seaborne traffic. Sea-level rise and coastal subsidence with tropical and extra-tropical storms 
Description of the Environment and Impact Analysis 4-35

exacerbate and accelerate the erosion of coastal barrier beaches along the Gulf Coast. Both the western 

edge of the Louisiana coast and the eastern Texas coast in the WPA received major damage as a result of 

Hurricanes Katrina, Rita, Gustav, and especially Ike. Texas barrier islands and mainland beaches lost 

elevation and vegetative cover as a result of the erosion accompanying the storm-driven debris and sheer 

tidal surge. The reduction in storm protection once provided by barrier islands will result in further 

conversion of freshwater marsh to either open water or salt marsh. Due to such hurricane-induced 

changes, the cumulative effect of additional storms has the potential to further erode barrier islands unless 

restoration methods are implemented.

Barrier beaches along coastal Louisiana have experienced severe erosion and landward retreat 

(marine transgression) because of natural processes enhanced by human activities. Adverse effects on 

barrier beaches and dunes have resulted from changes to the natural dynamics of water and sediment flow 

along the coast. This can happen due to anthropogenic attempts to control catastrophic floods and change 

the natural environment to better accommodate navigation on waterways used to support OCS Programand non-OCS Program-related vessel traffic. Sea-level rise and coastal subsidence, along with tropical 

and extra-tropical storms exacerbate and accelerate the erosion of coastal barrier beaches along the Gulf 

Coast of Louisiana. The CPA coast received major damage as a result of Hurricanes Katrina, Rita, and 

Gustav.

The central Gulf Coast (i.e., Louisiana, Mississippi, Alabama, and western Florida) and the associated 

barrier islands and beaches have experienced an increase in frequency of high-intensity hurricanes and 

tropical storms over the past several years. As a result of past powerful hurricanes (i.e., Hurricanes 

Katrina, Rita, and Gustav), changes in barrier island topography and decreases in beach elevation 

potentially increased the probability for oiling farther up the beach head in some locations. Due to the 

more gentle slopes, removal of beach ridges, and cuts into the mainland barrier beaches, the remnant 

transition zone between the water and the current beach ridge may be more vulnerable to spills. In some 

areas along the Louisiana coast, barrier islands were severely damaged, resulting in either heavily 

degraded beachfront elevations and ridges or submergence of the island from sediments being 

redistributed by the storm surge. In coastal Louisiana, dune-line heights have been drastically reduced by 

the storm activity. The Isle Dernieres and Chandeleur Island chains experienced beach erosion and losses 

in elevation. In Mississippi and Alabama, dune elevations exceed those in Louisiana but have been 

reduced to some extent due to storm activity. Hurricane Katrina completely inundated the western side of 

Dauphin Island, Alabama, decreasing elevations to less than 2 m (7 ft). Hurricane Gustav then 

completely overwashed the western edge of the island, resulting in large changes to the island’s shape and 

topography (USDOI, GS, 2008).

Hurricane Rita in September 2005 severely impacted the shoreface and beach communities of 

Cameron Parish in southwest Louisiana. These barriers lost elevation and vegetative cover as a result of 

the erosional forces accompanying the storm surge and scour from storm-driven debris (Barras, 2007a). 

The removal of vegetative cover and scour scars provides an avenue for additional erosion to occur as a 

result of inlet formations and tidal rivulets. 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 

provided by these barrier islands. The reduction in island elevation results in less frontline protection to 

valuable marshes and makes urban and industrial areas protected by these marshes at a higher risk 

(USDOC, NMFS, 2007).

Hurricanes and tropical storms will remain a part of the Gulf Coast weather pattern and will continue 

to affect the elevations of barrier islands, mainland beaches, and dunes. Depending on storm frequency 

and intensity, it may be possible for coastal restoration and protection projects to mitigate some of the 

physical damage to these areas.

Recreational Use and Tourism 

Most barrier beaches in Louisiana are relatively inaccessible for regular recreational use because they 

are in coastal areas with limited road access. Few of these beaches have been, or are likely to be, 

substantially altered to accommodate recreational or industrial construction projects in the near future. 
4-36 Central Planning Area Lease Sales 235, 241, and 247 EIS

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 Florida are accessible to people for recreational use because of 

road access, and their use is encouraged. Recreational use of barrier beaches and dunes can have impacts 

on the stability of the landform. Vehicle and pedestrian traffic on sand dunes can stress and reduce the 

density of vegetation that binds the sediment and stabilizes the dune. Destabilized dunes are more easily 

eroded by winds, waves, and traffic. Recreational vehicles and even hikers have caused problems where 

road access is available and the beach is wide enough to support vehicle use, as in Alabama, Florida, and 

a few places in Louisiana. Areas without road access have limited impacts by recreational vehicles. 

There will continue to be seaside real-estate development where road access is available. The protection 

of dunes, beaches, and coastal environments will be regulated through the Coastal Management Programs 

(CMP’s) of the State. This assures that projects are constructed consistent with the Federal CZMA

guidelines in order to preserve the integrity of the coastal ecosystem.

Summary and Conclusion

River channelization, sediment deprivation, tropical and extra-tropical storm activity, sea-level rise, 

and rapid submergence have resulted in severe, rapid erosion of most of the barrier and shoreline 

landforms along the Louisiana coast. The Deepwater Horizon explosion, spill, and response further 

impacted the Louisiana coast. The Mississippi, Alabama, and West Florida coasts have been impacted by 

storm activity; sea-level rise; the Deepwater Horizon explosion, spill, and response; development; 

recreational use; and tourism. The Texas coast has experienced landloss because of a decrease in the 

volume of sediment delivered to the coast because of channelization and damming of coastal rivers and 

subsidence along the coast. Storm-induced changes in hydrology have, in some cases, changed the 

current regime responsible for stabilizing the barrier islands. Beach stabilization projects are considered 

by coastal geomorphologists and engineers to accelerate coastal erosion. Beneficial use of maintenance 

dredged materials and other restoration techniques could be required to mitigate some of these impacts.

The impacts of oil spills from both OCS and non-OCS sources to the Gulf Coast should not result in 

long-term alteration of landforms if the beaches are cleaned using techniques that do not significantly 

remove sand from the beach or dunes. The majority of inshore spills are assumed to be small in scale and 

short in duration; therefore, impacts would be minor. Oil from most offshore spills is expected to be 

weathered and dissipated by the time it would contact coastal beaches. The cleanup impacts of these 

spills could result in short-term (up to 2 years) adjustment in beach profiles and configurations as a result 

of sand removal and disturbance during the cleanup operations. Some contact to lower areas of sand 

dunes is expected. These contacts would not result in significant destabilization of the dunes. Cleanup 

efforts would be monitored to allow the least amount of disturbance to the areas. The long-term stressors 

to barrier beach communities caused by the physical effects and chemical toxicity of an oil spill may lead 

to decreased primary production, plant dieback, and further erosion, particularly if oil is carried onto 

dunes by hurricanes. 

Under a CPA proposed action, 0-1 pipeline landfalls are projected. These pipelines are expected to 

be installed using modern techniques, which cause little to no impacts to the barrier islands and beaches. 

Existing pipelines, in particular those that are parallel and landward of beaches and that had been placed 

on barrier islands using older techniques that left canals or shore protection structures, have caused and 

would continue to cause barrier beaches to narrow and breach.

Most barrier beaches in Alabama and Florida are accessible to people for recreational use because of 

road access, and their use is encouraged. Recreational use of barrier beaches can be intense depending on 

the area. In 2012, the Gulf Islands National Seashore had approximately 4.9 million visitors (USDOI, 

NPS, 2013). This ranked it the ninth most visited National Parks Unit, placing it ahead of parks like the 

Grand Canyon and Yosemite. Excessive recreational use can result in damage to dunes resulting from the 

loss of dune stabilizing plants. Destabilized dunes are more easily eroded by winds waves and human 

traffic. Restoration to repair and mitigations to minimize damages to beaches from both natural and 

human impacts are common in many of the developed beachfronts. Areas without road access have 

limited impacts by recreational vehicles.

In conclusion, coastal barrier beaches have experienced severe adverse cumulative impacts from 

natural processes and human activities. Natural processes are generally considered the major contributor 

to these impacts, whereas human activities cause severe local impacts and accelerate the natural processes 
Description of the Environment and Impact Analysis 4-37

that deteriorate coastal barriers. Human activities that have caused the greatest adverse impacts are river 

channelization and damming, pipeline canals, navigation channel stabilization and maintenance, reduction 

in sand budgets, and beach stabilization structures.

A CPA proposed action is not expected to adversely alter barrier beach configurations significantly 

beyond existing, ongoing impacts in localized areas downdrift of artificially jettied and maintained 

channels. A CPA proposed action may extend the life and presence of facilities in eroding areas, which 

would cause continued erosion in those areas. A CPA proposed action is not expected to increase the 

probabilities of oil spills beyond the current estimates. Strategic placement of dredged material from 

channel maintenance, channel deepening, and related actions can mitigate adverse impacts upon those 

localized areas.

The extent of impacts from the Deepwater Horizon explosion, oil spill, and response to coastal barrier 

beaches and associated dunes remains unclear at this time. This information is being developed through 

the NRDA process, data are still incoming and have not been made publicly available, and it is expected 

to be years before the information is available. Where this incomplete information is relevant to 

reasonably foreseeable impacts, what scientifically credible information is available was used in its stead 

and applied using accepted scientific methodologies. Although it may be relevant to reasonably 

foreseeable adverse impacts, this incomplete or unavailable information is not essential to a reasoned 

choice among alternatives. Compared with other impacting factors on coastal barrier beaches and dunes, 

the incremental contribution of a CPA proposed action to the cumulative impacts to these resources is 

expected to be small.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search was conducted for information published on barrier beaches and dunes, and various Internet 

sources were examined to determine any recent information regarding barrier beaches and dunes. 

Sources investigated include BOEM; the U.S. Department of the Interior, Geological Survey (USGS); 

National Wetlands Research Center; the USGS Gulf of Mexico Integrated Science Data Information 

Management System; Gulf of Mexico Alliance; State environmental agencies; USEPA; and coastal 

universities. Other websites from scientific publication databases (including Science Direct, Elsevier, the 

NOAA Central Library National Oceanographic Data Center, and JSTOR) were checked for new 

information using general Internet searches based on major themes. Most new and pertinent information 

has been the result of Deepwater Horizon-related research, and these studies have provided insight into 

many aspects of the spill and its effects as it relates to beach and dune environments.

Various studies examined changes to microbial communities after exposure to crude oil and/or 

dispersant, such as increased dominance in fungal communities (Bik et al., 2012) and increased 

abundance of hydrocarbon degraders (Kostka et al., 2011). Hamdan and Fulmer (2011) demonstrated 

inhibition of hydrocarbon degrading bacteria by exposure to dispersant, and Zuijdgeest and Huettel 

(2012) found that COREXIT caused faster penetration of PAH’s into sandy sediments, resulting in 

slowed degradation under anaerobic conditions. Other studies showed that biostimulation with nutrients 

or organic matter enhanced biodegradation of crude oil by autochthonous microbial consortia 

(Nikolopoulou et al., 2013; Horel et al., 2012; Mortazavi et al., 2012). A study of the bacteria present in 

tarballs collected from beaches suggested that tarballs can act as reservoirs for bacteria, particularly 

human pathogens such as Vibrio vulnificus (Tao et al., 2011).

Still other studies focused on determining the source of tarballs and dispersant-related chemicals. 

Mulabagal et al. (2013) found that tarballs on Alabama beaches originated from the Deepwater Horizon

explosion and oil spill, while Hayworth and Clement (2012) traced dispersant-related chemicals found in 

nearshore and inland water samples from the Orange Beach, Alabama, vicinity to local stormwater 

discharge rather than COREXIT.

While the recent research has provided new information regarding impacts to coastal beaches and 

dunes from oil spills, this new information does not change the conclusions of the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS because such a low-probability catastrophic 

event is unlikely to occur and because BOEM has already considered the potential irreversible effects to 

coastal beaches and dunes in Appendix B of this Supplemental EIS.

As identified in the resource analyses above and in Chapter 4.2.1.3 of the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, incomplete or unavailable information 
4-38 Central Planning Area Lease Sales 235, 241, and 247 EIS

regarding coastal barrier beaches and associated dunes in the CPA may be relevant to reasonably 

foreseeable significant adverse effects. BOEM has determined that the information is not essential to a 

reasoned choice among alternatives.

4.1.1.4. Wetlands

BOEM has reexamined the analysis for wetlands presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented below. No 

new significant information was discovered that would alter the impact conclusion for wetlands presented 

in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

A detailed description of wetlands and the full analyses of the potential impacts of routine activities 

and accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.4 of the 

2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.4 of the WPA 

233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the cumulative 

impacts is presented below. Any new information that has become available since those documents were 

published is presented below.

Impacts of Routine and Accidental Events

The potential routine impact-producing factors on wetlands of the CPA 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 coastal areas. Other potential impacts that are indirectly associated with OCS oil and gas activities are 

wake erosion resulting from navigational traffic, levee construction that prevents necessary sedimentary 

processes, saltwater intrusion that changes the hydrology leading to unfavorable conditions for wetland 

vegetation, and vulnerability to storm damage from eroded wetlands. A detailed impact analysis of the 

routine impacts of OCS activities associated with a CPA proposed action on wetlands can be found in 

Chapter 4.2.1.4.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.4 of the WPA 233/CPA 231 Supplemental EIS.

It is expected that impacts of pipelines would be reduced or eliminated through mitigation, such as 

horizontal, directional (trenchless) drilling techniques to avoid damages to these sensitive wetland 

habitats. Although maintenance dredging of navigation channels and canals in the CPA is expected to 

occur, a CPA proposed action is expected to contribute minimally to the need for this dredging. 

Alternative dredged-material disposal methods can be used to enhance and create wetlands. Secondary 

impacts to wetlands from a CPA 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 wetlands from routine activities associated with a CPA proposed action are expected to be low due to 

the small length of projected onshore pipelines, the minimal contribution to the need for maintenance 

dredging, and the mitigation measures that would be used to further reduce these impacts.

Accidental disturbances resulting from a CPA proposed action, mainly oil spills, have the potential to 

cause plant mortality and permanent loss of wetlands of the CPA. A detailed impact analysis of the 

accidental impacts that may be associated with proposed CPA Lease Sales 235, 241, and 247 on wetlands 

can be found in Chapter 4.2.1.4.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.4 of the WPA 233/CPA 231 Supplemental EIS.

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

and damaging wetlands along the Gulf Coast, except in the case of a low-probability catastrophic event, 

which is not reasonably expected and not part of a CPA proposed action (refer to Appendix B). This is 

because of the distance of the spill to the coast, the likely weathered condition of oil (through evaporation, 

dilution, and biodegradation) should it reach the coast, and because wetlands are generally protected by 

barrier islands, peninsulas, sand spits, and in some cases by currents. However, because the protective 

capacity of barrier islands has been reduced (due to land lost in hurricanes and anthropogenic factors; 

refer to Chapter 4.1.1.3), there is a greater potential for the oiling of coastal wetlands during an 

accidental event. The causes of coastal and offshore oil spills are summarized in Chapters 3.1.1.7 and 

3.3.5.2. Although the probability of occurrence is low, the greatest threat from an oil spill to wetland 

habitat is from an inland spill as a result of a nearshore vessel accident or pipeline rupture. Wetlands in 

the northern Gulf of Mexico are in moderate- to high-energy environments; therefore, sediment transport 
Description of the Environment and Impact Analysis 4-39

and tidal stirring should reduce the chances for oil persisting in the event that these areas are oiled. While 

a resulting slick may cause minor impacts to wetland habitat and surrounding seagrass communities, the 

equipment, chemical treatments, and personnel used for cleanup can generate the greatest impacts to the 

area. Associated foot traffic may work oil farther into the sediment than would otherwise occur. Close 

monitoring and restrictions on the use of bottom-disturbing equipment would be needed to avoid or 

minimize those impacts. In addition, an assessment of the area covered, oil type, and plant composition 

of the wetland oiled should be made prior to choosing remediation treatment. These treatments could 

include mechanical and chemical techniques with onsite technicians. Overall, impacts to wetland habitats 

from an oil spill associated with activities related to a CPA proposed action would be expected to be low 

and temporary because of the nature of the system, regulations, and specific cleanup techniques.

For example, Michel et al. (2013), Kokaly et al. (2013), and Mishra et al. (2012) demonstrate that 

understanding the extent of the oil spill in terms of the length of shoreline affected and the penetration 

into wetlands from the shoreline will help in setting the visual contexts to detect possible long-term 

recovery trends. This includes the usefulness of monitoring techniques such as remote sensing (of oil 

impacts), bioremediation, bioaugmentation, and microbial degradation, along with natural weathering to 

help in the recovery of oiled marsh vegetation (DeLaune and Wright, 2011; Horel et al., 2012; Liu et al., 

2012; Tao and Yu, 2013; Natter et al., 2012; Beazley et al., 2012). Other techniques, such as the use of 

barriers such as booms and sand berms, did not work as well as planned (Martinez et al., 2011; Jones and 

Davis, 2011; Zengel and Michel, 2013). Research has shown that marsh vegetation recovers from many 

disturbances, including oil exposure (DeLaune and Wright, 2011; Silliman et al., 2012). Even though 

some marsh vegetation is more resilient than others, all marsh vegetation will be adversely impacted if 

there is 100-percent oil coverage of the plant (Lin and Mendelssohn, 2012; Wu et al., 2012b; Mishra 

et al., 2012). The impact of oil on resident and transient marsh nekton and arthropods has been shown to 

be short term in nature, with these communities near pre-spill levels a year after the Deepwater Horizon

oil spill (Moody et al., 2013; McCall and Pennings, 2012).

Summary and Conclusion

The impacts to wetlands from activities associated with a CPA proposed action are expected to be 

low because 0-1 pipeline landfalls are projected, 0-1 new gas processing facilities are expected, and the 

contribution from a CPA proposed action to the need for maintenance dredging would be minimal. The 

wetlands that would be associated with a CPA proposed action have a minimal probability for oil-spill 

contact.

Cumulative Impacts

Background/Introduction 

This cumulative analysis considers the effects of impact-producing factors related to a CPA proposed 

action, prior and future OCS sales in the Gulf of Mexico, State oil and gas activities, other governmental 

and private projects and activities, and pertinent natural processes that may affect wetland resources.

Wetlands are vulnerable to many impact-producing factors from OCS oil- and gas-related impacts 

and non-OCS oil- and gas-related impacts. Specific OCS oil- and gas-related, impact-producing factors 

considered in this cumulative analysis include the following: (1) oil spills; (2) OCS oil- and gas-related 

vessel traffic; (3) construction of OCS oil- and gas-related infrastructure and support structure (including 

pipelines); and (4) waste disposal. Other non-OCS oil- and gas-related impact-producing factors would 

potentially impact wetland resources, including the following: (1) State oil and gas activities; (2) nonOCS 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 CPA proposed action would not greatly 

increase the overall impacts.
4-40 Central Planning Area Lease Sales 235, 241, and 247 EIS

OCS Oil- and Gas-Related Impacts 

Oil Spills

The potential for coastal/inland oil spills creates the greatest concern for coastal wetlands 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.

Over 3,000 production platforms in the Gulf are over 20 years old and were constructed prior to the 

modern structural requirements that increase endurance to hurricane force winds (Casselman, 2010). 

Improperly capped or marked abandoned wells also add to the possibility for future oil spills as a result of 

leaks or vessel collisions. Future spills from these types of facilities would be less likely because these 

older facilities are gradually either structurally updated to withstand larger storms or replaced at the 

discretion of the owner/operator.

Oil from offshore spills is less likely to reach the coastal wetlands in the same condition it was 

released due to weathering, dispersant treatment, and blockage by barrier islands and shorelines. 

However, erosion of these barriers by Hurricanes Katrina and Rita decreased the level of protection 

afforded the mainland (USDOC, NMFS, 2007a). Flood tides may now bring some oil through tidal inlets 

into areas landward of barrier beaches. The turbulence of tidal water passing through most tidal passes 

would break up the slick, thereby accelerating dispersion and weathering. For the majority of these 

situations, light oiling of vegetated wetlands may occur. Any adverse impacts that may occur to wetland 

plants are expected to be short lived, generally less than 1 year.

Spills that occur in or near the Chandeleur or Mississippi Sounds could affect wetland habitat in or 

near 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). Because of their natural history, these areas are considered areas of special 

importance. They also support endangered and threatened species. Although the wetland acreage on 

these islands is small, the wetlands make up an important element in the habitat of the islands. The inlets 

that connect the Mississippi Sound with the marsh-fringed estuaries and lagoons within the islands are 

narrow, so a small percentage of the oil that contacts the Sound side of the islands would be carried by the 

tides into interior lagoons.

The 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. Therefore, the coastal waters of Louisiana, Mississippi, and 

Alabama would have a total of 200, 30, and 10 spills <1,000 bbl/yr, respectively, from all sources. When 

limited to just oil- and gas-related spill sources such as platforms, pipelines, MODU’s, and support 

vessels, Louisiana, Mississippi, and Alabama would have a total of 130-170, 3-5, and about 2 spills 

<1,000 bbl/yr, respectively.

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 east of the Texas/Louisiana State line 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. However, unlike other 

historic large spills (Exxon Valdez and Ixtoc I), the oil was released and treated in deep water nearly 77 

km (48 mi) from shore, and the spill occurred in an unconfined open ocean as opposed to a sheltered 

embayment. All of these factors contribute to the weathering and detoxification of the oil that reached the 

shoreline. It is too early to determine the cumulative long-term effect of this spill and its contribution to 

the ongoing marsh loss or the acceleration of that loss. While low-probability catastrophic spills, which 

are not reasonably foreseeable and not part of a CPA proposed action, could occur in the future as a result 

of human error, new regulations focusing on improved safety, more regulatory checks, and inspections 

should decrease the already small likelihood of the occurrence of such spills. Accidental spills as a result 

of a low-probability catastrophic event, which is not reasonably foreseeable and not part of a CPA 

proposed action, are discussed in Appendix B. 

Vessel Traffic

Navigation channels in the coastal areas of the CPA support both OCS and non-OCS vessel traffic. 

Waves generated by boats, ships, barges, and other vessels erode unprotected shorelines and accelerate 
Description of the Environment and Impact Analysis 4-41

erosion in areas already affected by the natural erosion process. This is evident along the Texas coast 

where heavy traffic using the Gulf Intracoastal Waterway has accelerated the erosion of existing salt 

marsh habitat.

BOEM conservatively estimates that there are approximately 4,850 km (3,013 mi) of Federal 

navigation channels, bayous, and rivers potentially exposed to OCS oil- and gas-related traffic in the 

EPA, CPA, and WPA (Table 3-7) and that the average canal is widening at a rate of 0.99 m/year 

(3.25 ft/year). Gulfwide, the average canal widening rate results in a total annual landloss of 

approximately 831 ac/yr (336 ha/yr). Therefore, over the 40-year cumulative activities scenario, landloss 

in Federal navigation channels could total approximately 33,221 ac (13,444 ha). Total landloss in these 

areas can be caused by multiple factors, including saltwater intrusion, hurricanes, and vessel traffic. The 

OCS oil- and gas-related traffic constitutes a larger percent of the total vessel traffic (OCS oil- and gasrelated and non-OCS oil- and gas-related) in the CPA (12-16%) than in the WPA (3-5%). All service 

vessels associated with EPA actions are assumed to use CPA navigational canals while inland and 

constitute less than 1 percent of the total vessel traffic. Assuming that vessel traffic alone was the sole 

source of erosion, the rate of landloss would be related to the usage of those canals by both OCS oil- and 

gas-related vessels and non-OCS oil- and gas-related vessel traffic. Using the estimated proportion of 

OCS oil- and gas-related vessel traffic as a measurement of erosion, BOEM conservatively estimates the 

OCS oil- and gas-related contribution to bank erosion over the 40-year cumulative scenario to be 2,766-

3,645 ac (1,119-1,475 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 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 will be lost in the next 50 years 

(or approximately 896,000 ac [362,600 ha] of land in the next 40 years). Using BOEM’s conservative 

estimate of approximately 2,360 km (1,470 mi) of Federal navigation channels, bayous, and rivers 

potentially exposed to OCS traffic in the LCA (Table 3-7) and the average canal widening rate of -

0.99 m/yr (-3.25 ft/yr), a total landloss of approximately 16,190 ac (6,550 ha) in navigation canals may be 

estimated over the next 40 years. Using this estimate and comparing it with the total expected landloss in 

coastal Louisiana over the next 40 years, BOEM estimates that approximately 2 percent of the total 

landloss in Louisiana will occur due to saltwater intrusion, hurricanes, and vessel traffic (OCS oil- and 

gas-related and non-OCS oil- and gas-related) in navigation canals. Because OCS oil- and gas-related 

vessel traffic constitutes only 12-16 percent of the total vessel traffic in the CPA, BOEM conservatively 

estimates that OCS oil- and gas-related vessel traffic would contribute <0.5 percent (or <2,647 ac 

[1,071 ha]) of the landloss in coastal Louisiana in the next 40 years.

Depending upon the regions and soils through which canals were dredged, their secondary adverse 

impacts may be more locally significant than direct impacts. The OCS oil- and gas-related vessel traffic 

is expected to result in some level of dredging activity associated with the expansion of offshore 

platforms or onshore transfer or production facilities if needed. The primary indirect impacts from 

dredging would be wetland loss as a result of saltwater intrusion or vessel-traffic erosion. However, the 

primary support, transfer, and production facilities used for OCS oil- and gas-related activities are located 

along armored canals and waterways, thus minimizing marsh loss. In the foreseeable future, there will be 

a continuing need for dredged material for coastal restoration, wetland creation and, to some extent, 

offshore sediments (e.g., sand, etc.) needed for beach restoration and hurricane protection. Alternative 

dredged-material disposal methods can be beneficially used for wetland creation or restoration as required 

by COE’s permitting program.

Coastal Infrastructure and Pipelines 

Various kinds of onshore facilities service OCS development. Projected new facilities that are 

attributed to the OCS Program and a CPA proposed action would not be in wetland areas. State and 

Federal permitting agencies discourage the placement of new facilities or expansion of existing facilities 

in wetlands. Any impacts upon wetlands from existing facilities are expected to be mitigated. Because of 

existing capacity, no additional expansion into wetland areas is expected.

Activities that would further accelerate wetland loss include additional construction of access 

channels to shoreline staging areas and expansion or construction of onshore and offshore facilities 

(receiving and transfer facilities or fabrication of production platforms). BOEM projects 0-1 new gas 
4-42 Central Planning Area Lease Sales 235, 241, and 247 EIS

processing facilities and 0-1 new pipeline landfalls for a CPA proposed action. However, based on the 

most current information available, there is only a very slim chance that either would result from a CPA 

proposed action, and if a new gas processing facility or pipeline landfall were to result, it would likely 

occur toward the end of the 40-year analysis period. The likelihood of a new gas processing facility or 

pipeline landfall is much closer to zero than to one (Dismukes, official communication, 2013a). A more 

detailed description of coastal infrastructure is provided in Chapter 4.1.1.23.1. 

Modern pipeline installation methods that use horizontal (trenchless) drilling allow pipelines to be 

installed under coastal habitats such as barrier islands and beaches as well as fringe marshes, and 

therefore, eliminate or greatly reduce impacts to these habitats. The addition of corrosion preventatives to 

the pipeline itself reduces the probability of accidental leakage from aging pipelines. These techniques, in 

combination with “tie ins” to existing Federal or State pipelines with shore connections, further reduces 

the number of new pipeline landfalls and their cumulative impact. While impacts are greatly reduced by 

mitigation techniques, remaining impacts may include expansion of tidal influence, saltwater intrusion, 

hydrodynamic alterations, erosion, sediment transport, and habitat conversion (Cox et al., 1997; Morton, 

2003; Ko and Day, 2004). The majority (over 80%) of previous OCS oil- and gas-related direct landloss 

is estimated to be caused by OCS pipelines (Turner and Cahoon, 1987). These are seaward of the inland 

CZM boundary to the 3-mi (5-km) State/Federal boundary offshore of Louisiana, Mississippi, and 

Alabama. Of those pipelines, about 8,000 km (4,971 mi) cross wetland and upland habitat, and they 

mainly occur in Louisiana. The remaining 7,400 km (4,595 mi) of pipeline cross waterbodies (Johnston 

et al., 2009). The total length of non-OCS pipelines through wetlands is believed to be approximately 

twice that of the Gulf OCS Program, or about 15,285 km (9,492 mi). There is a total (OCS and nonOCS) of approximately 23,285 km (14,460 mi) of pipelines through Louisiana coastal wetlands. The 

majority of OCS pipelines entering State waters ties into existing pipeline systems and does not result in 

new landfalls. Pipeline maintenance activities that disturb wetlands are very infrequent and are mitigated 

to the maximum extent practicable. Such activities would be subject to 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 widening of OCS pipeline canals does not appear to be an important factor contributing to OCS 

oil- and gas-related direct landloss. This is because few pipelines are open to navigation, and the impact 

width does not appear to be significantly different from that for open pipelines closed to navigation. 

Based on the projected coastal Louisiana wetlands loss of from 419,000 to 925,000 ac (169,000-

374,000 ha) (Couvillion et al., 2013), landloss resulting from new OCS pipeline construction represents 

<1 percent of the total expected wetlands loss for that time period. This estimate does not take into 

account the present regulatory programs and modern installation techniques. Today, pipeline canals are 

much narrower than in the past because of advances in technology and improved methods of installation. 

These advances are due to a greater awareness among regulatory agencies and industry (Johnston et al., 

2009). The magnitude of impacts from OCS oil- and gas-related pipelines is inversely proportional to the 

quantity and quality of mitigation techniques applied. Pipelines with extensive mitigation measures 

appeared to have minimal impacts, while pipelines without such measures contributed to significant 

habitat changes. Impacts can be minimized or altogether avoided through proper construction methods, 

mitigation, and maintenance. BOEM is not a permitting agency for onshore pipelines. The permitting 

agencies are COE and the State in which the activity has occurred or would occur. Therefore, it would be 

the responsibility of COE and the States to ensure that wetland impacts resulting from pipeline 

construction are properly mitigated and monitored. Throughout the 40-year life of a CPA proposed 

action, 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 inland pipeline system may temporarily 

impact wetlands in the pipeline corridors, but 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 will increase in nearshore, inland, and offshore waters.

Waste Disposal

The past discharge of saltwater and drilling fluids associated with oil and gas development has been 

responsible for the decline or death of some marshes (Morton, 2003). Discharging OCS oil- and gasrelated produced water into inshore waters has been discontinued, so all OCS oil and gas produced waters
Description of the Environment and Impact Analysis 4-43

are discharged into offshore Gulf waters in accordance with NPDES permits, or injected. Produced 

waters from the OCS are not expected to affect coastal wetlands. Produced sands, oil-based or syntheticbased 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 USEPA for handling these materials. Sufficient disposal capacity is assumed to be available 

in support of a CPA proposed action. Because of wetland-protection regulations, no new waste disposal

site would be developed in wetlands. Some seepage from waste sites into adjacent wetland areas may 

occur and result in damage to wetland vegetation.

Non-OCS Oil- and Gas-Related Impacts

State Oil and Gas 

Impacts from State onshore oil and gas activities are expected to occur as a result of oil spills, 

dredging for new canals, maintenance, and usage of existing rig access canals and drill slips, and for 

preparation of new well sites. Indirect impacts from dredging new canals for State onshore oil and gas 

development and from the maintenance of the existing canal network are expected to continue. 

Insignificant adverse impacts upon wetlands from maintenance dredging are expected because the large 

majority of the material would be placed in existing disposal areas or because alternate bank disposal 

techniques would be used. The alternate bank disposal technique creates gaps to maintain hydrological 

connections and tidal circulation important in maintaining a functioning wetland. State onshore oil and 

gas activities also contribute to vessel traffic and the wetland impacts associated with such traffic, as 

described above.

Other impacts stem from State oil and gas activity. Locally, 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 drowning of marsh plants and 

conversion to open water. Non-OCS oil- and gas-related oil spills can occur in coastal regions as a result 

of import tankers, barge or shuttle tanker accidents during transit or offloading, coastal oil production 

activities, and various kinds of petroleum product transfer accidents. Numerous wetland areas have 

declined or been destroyed as a result of oil spills caused by pipeline breaks or tanker accidents.

Oil stresses the wetland communities, making them more susceptible to saltwater intrusion, drought, 

disease, and other stressors (Ko and Day, 2004). The past discharge of saltwater and drilling fluids 

associated with oil and gas development has been responsible for the decline or death of some local 

marshes (Morton, 2003).

Vessel Traffic and Navigation Canals 

Vessel traffic in the CPA includes commercial shipping, support for oil and gas activities, commercial 

and recreational fishing vessels, pleasure boating, and other types of 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. In many cases this erosion results in wetland loss. Navigation 

channels require routine maintenance dredging. Insignificant adverse impacts upon wetlands from 

maintenance dredging are expected because the large majority of the material would be disposed upon 

existing disposal areas. However, due to the fluid nature of the dredged material, indirect impacts may 

occur as a result of disposal site widening and converting lower elevations to higher ground. This 

elevation change could convert existing wetland areas to uplands. Alternative dredged material disposal 

methods can be used to enhance and create coastal wetlands.

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. Subtracting 

projected landlosses of 16,190 ac (6,550 ha) caused by bank widening of navigation channels in the LCA 

from land added or protected by beneficial uses of dredged material, an estimated net gain of 33,800 ac 

(13,700 ha) between the years 2013 and 2063 could occur (refer to the calculations in “OCS Oil- and GasRelated Impacts” above).
4-44 Central Planning Area Lease Sales 235, 241, and 247 EIS

Depending upon the region and the dredged soil type, secondary adverse impacts of canals may be 

more locally significant than direct impacts. Additional wetland losses may be generated by the 

secondary impacts of saltwater intrusion, flank subsidence, freshwater-reservoir reduction, and deeper 

tidal penetration. A variety of mitigation efforts have been initiated to protect against direct and indirect 

wetland loss. The failure to maintain mitigation structures that reduce canal construction impacts can 

have substantial impacts upon wetlands. These localized impacts are expected to continue.

Navigation channels contribute to the negative effects 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.” The Calcasieu Ship Channel is a good example 

of how saltwater intrusion, as a consequence of channelization, results in significant habitat transition 

from freshwater to brackish water to saltwater and ultimately to open-water systems. Another 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) among old, dead cypress tree trunks.

Onshore activity that would further accelerate wetland loss includes additional construction of access 

channels (for instance at fabrication yards) and onshore action needed for the construction of new well 

sites and the expansion or construction of onshore production facilities or receiving and transfer facilities. 

Most of these facilities would be located in Louisiana and would minimally impact wetlands. 

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).

Coastal Infrastructure and Development 

The development of wetlands for agricultural, residential, industrial, commercial, and silvicultural 

(forest expansion) uses would continue but with more regulatory and planning constraints. Impacts from 

these developments are expected to continue in coastal regions around the around the Gulf.

Development pressures in the coastal regions of Texas have been primarily the result of tourism and 

residential beach side development in the Galveston and Bolivar Peninsula areas. In Galveston, 

recreation and tourist developments have been particularly destructive. These trends are expected to 

continue, but since Hurricane Ike, redevelopment is being coordinated with the natural resource agencies 

in an effort to assure compatibility of the new construction with the coastal environment to minimize 

impacts.

Development pressures in the coastal regions of Louisiana, Mississippi, Alabama, and Florida have 

caused the destruction of large areas of wetlands. In coastal Louisiana, the most destructive 

developments have been the inland oil and gas industry projects, which have resulted in the dredging of 

huge numbers of access channels. Agricultural, residential, industrial, and commercial developments 

have caused the most destruction of wetlands in Mississippi, Alabama, and Florida. In Florida, 

recreational and tourist developments have been particularly destructive. These trends are expected to 

continue. During the next 40 years, from 419,000 to 925,000 ac (169,000-374,000 ha) of wetlands would 

be lost from the Louisiana coastal zone (Couvillion et al., 2013), and 1,600-2,000 ha (647-809 ac) would 

be lost from the Mississippi coastal zone. Wetland losses in the coastal zones of Alabama and Florida are 

assumed to be comparable with those in Mississippi.

Infrastructure associated with State oil and gas activity has taken a tremendous toll on coastal 

wetlands, particularly in Louisiana, primarily due to construction of access canals, drilling slips, and 

pipeline canals (Turner et al., 1994). Many pipelines carry product from both OCS and non-OCS sources. 

Impacts from pipeline construction due to non-OCS oil and gas activity are similar to impacts due to OCS 

oil and gas activity. Infrastructure that serves the transportation of foreign oil, such as oil ports, can have 

wetland impacts to the extent they are constructed on or adjacent to wetlands. New and existing pipeline 

channels would continue eroding, largely at the expense of wetlands; however, protective channel armor 

may be added at a later date. The current regulatory programs, modern construction techniques, and 

mitigations have reduced recent impacts to wetlands from pipeline installation.

Existing regulations and development permitting procedures indicate that development-related 

wetland loss may be slowed. Wetland damage would be minimized through the implementation of 

CZMA guidelines and enforceable policies, COE regulatory guidelines for wetland development, and 

various State and Federal coastal development programs. Examples of these programs are the Coastal 
Description of the Environment and Impact Analysis 4-45

Impact Assistance Program (CIAP), the Coastal Wetlands Planning, Protection, and Restoration Act 

(CWPPRA), and the Louisiana Coastal Protection and Restoration Authority (refer to Chapter 4.2.1.4.4 of 

the 2012-2017 WPA/CPA Multisale EIS).

Renewable energy facility construction could potentially impact wetlands, if for instance transmission 

lines coming from offshore wind turbines necessitated construction of onshore transmission substations in 

the coastal zone. Impacts to wetlands would be negligible.

Natural Processes

Along with increased human activities, the recent increase in intensity and frequency of hurricanes in 

the Gulf (Stone et al., 2004) has greatly impacted the system of protective barrier islands, beaches, and 

dunes and associated wetlands along the Gulf Coast. Intense storms typically erode all of the vegetation 

and soil from some areas of marsh, leaving behind a body of water, as seen with Hurricane Isaac. These 

storm events will continue to impact the Gulf of Mexico coast.

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 to be subsidence. He found that the 

“Northern Gulf of Mexico continental margin is segmented by northwest-southeast trending transfer fault 

zones related to Mesozoic rifting.”

It was estimated in 2000 that coastal Louisiana would continue to lose land at a rate of approximately 

26 km2

/yr (10 mi2/yr) over the next 50 years. This would be expected to result in an additional net loss of 

1,326 km2 (512 mi2

) by 2050, which is almost 10 percent of Louisiana’s remaining coastal wetlands

(Barras et al., 2003). However, in 2005, Hurricanes Katrina and Rita caused 562 km2 (217 mi2

) of land 

change (primarily wetlands to open water) (Barras, 2006). Based on the analysis of the latest satellite 

imagery, approximately 212 km2 (82 mi2

) of additional open-water habitat was in areas primarily 

impacted by Hurricane Katrina (e.g., Mississippi River Delta Basin, Breton Sound Basin, Pontchartrain 

Basin, and Pearl River Basin) (Barras, 2007b and 2009). Also, 256 km2 (99 mi2

) of open-water habitat 

was in areas primarily impacted by Hurricane Rita (e.g., Calcasieu/Sabine Basin, Mermentau Basin, 

Teche/Vermilion Basin, Atchafalaya Basin, and Terrebonne Basin). Barataria Basin contained 

approximately 46.6 km2 (18 mi2

) of new open-water habitat caused by both hurricanes. These new openwater habitats represent landloss caused by the direct removal of wetlands. They may also indicate 

transitory changes of wetlands to open water caused by remnant flooding, removal of aquatic vegetation, 

and scouring of marsh vegetation. However, it is possible that the apparent increase in open water is 

partly due to water-level variation attributed to normal tidal and meteorological variation between satellite 

images. The presence of strong tropical storms is a routine background condition in the Gulf that must be 

taken into consideration. Coastal change from storms in the area included both beach erosion and the 

erosion of channels where water continues to flow seaward to the Gulf of Mexico (Doran et al., 2009). 

Eroded barriers that once protected the wetlands behind them were severely eroded by the storms. These 

factors have led to a steep increase in the recent landloss projections cited above (Couvillion et al., 2013).

Sea-Level Rise

There is increasing new evidence of the importance of the effect of sea-level rise (or marsh 

subsidence) as it relates to the loss of marsh or changes in marshes, marsh types, and plant diversity 

(Spalding and Hester, 2007). The Spalding and Hester (2007) study shows that the very structure of 

coastal wetlands would likely be altered by sea-level rise because community shifts will be governed by 

the responses of individual species to new environmental conditions.

Gulf Coast wetlands tend to occur at low elevations, often between 1 and 2 ft (0.3-0.6 m) above sea 

level. It is obvious that if current projections are realized, and for example, 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 that time, in spite of organic accretion. A more conservative estimate of sealevel 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 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 
4-46 Central Planning Area Lease Sales 235, 241, and 247 EIS

wetlands can be expected to convert to open water as low-lying coastal marshes are inundated (refer to 

Chapter 3.3.4.1). 

Summary and Conclusion 

Cumulative impacts to wetlands are caused by a variety of factors, including pipeline emplacement, 

construction, dredging, oil spills, coastal development, and natural phenomena. The impacts to wetlands 

from activities associated with a CPA proposed action are expected to be low because 0-1 pipeline 

landfalls are projected, 0-1 new gas processing facilities are expected, and the contribution from a CPA 

proposed action to the need for maintenance dredging would be minimal.

Wetlands are most vulnerable to inshore or nearshore oil spills, which are primarily localized in 

nature. Spill sources include vessel collisions, pipeline breaks, and shore-based transfer, refining, and 

production facilities. A CPA proposed action would have a minimal probability for causing oil-spill 

contact with wetlands. This reduced risk is due to the distance of the offshore facility to wetland sites, 

beach and barrier island topography (although reduced locally post-Hurricanes Katrina, Rita, Gustav, and 

Ike), and product transportation through existing pipelines or pipeline corridors. Wetlands can still be at 

risk for offshore spills, but the risks are minimized by distance, time, sea conditions, and weather. 

Offshore spills related to a CPA proposed action are not expected to reach wetlands with toxicity 

approaching that of the initial release because of distance to shore and weathering. If they do reach shore, 

only light localized impacts to inland wetlands would occur. If any inshore spills occur, they will likely 

be small and at service bases or other support facilities, and these small-scale local spills would not be 

expected to severely affect wetlands beyond local impacts.

Development pressures in the coastal regions of Texas have been primarily the result of tourism and 

residential beach side development. These trends are expected to continue, but since Hurricane Ike, 

redevelopment is being coordinated with the natural resource agencies in an effort to assure compatibility 

of the new construction with the coastal environment to minimize impacts. The cumulative effects of 

human and natural activities in the coastal area have severely degraded the deltaic processes and have 

shifted the coastal area from a condition of net land building to one of net landloss. Deltaic Louisiana is 

expected to continue to experience the greatest loss of wetland habitat in the Gulf of Mexico. Wetland 

loss is also expected to continue in coastal Mississippi, Alabama, and Florida, but at slower rates. The 

incremental contribution of a CPA proposed action to the cumulative impacts on coastal wetlands is 

expected to be small.

A CPA proposed action represents a small (>5%) portion of the OCS impacts that will occur over the 

40-year analysis period. Impacts associated with a CPA proposed action are a minimal part of the overall 

OCS impacts. The incremental contribution of a CPA proposed action to the cumulative impacts on 

coastal wetlands is expected to be small.

BOEM acknowledges that there remains incomplete and unavailable information that may be relevant 

to reasonably foreseeable significant impacts on wetlands. 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 Supplemental EIS, BOEM believes that the incomplete or 

unavailable information regarding effects of Deepwater Horizon explosion, oil spill, and response on 

wetlands would likely not be essential to a reasoned choice among alternatives. This information will 

certainly not be available within the timeline contemplated in the NEPA analysis of this Supplemental 

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

the timeline contemplated in the NEPA analysis of this Supplemental EIS. The BOEM subject-matter 

experts have used what scientifically credible information is available in their analyses, and applied it 

using accepted scientific methodology.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search was conducted for information published on northern Gulf of Mexico wetland communities, 

and various Internet sources were examined to determine any recent information regarding these 

communities. Sources investigated include BOEM, the USGS National Wetlands Research Center, the 

USGS Gulf of Mexico Integrated Science Data Information Management System, Gulf of Mexico 
Description of the Environment and Impact Analysis 4-47

Alliance, State environmental agencies, USEPA, and coastal universities. Other websites from scientific 

publication databases (including Science Direct, Elsevier, the NOAA Central Library National 

Oceanographic Data Center, and JSTOR) were checked for new information using general Internet 

searches based on major themes. A recently released report provides an update on the status and trends of 

coastal wetlands (Dahl and Stedman, 2013). Numerous studies have been published regarding impacts of 

the Deepwater Horizon explosion, oil spill, and response.

While the recent research has provided much new information regarding impacts to wetlands from oil 

spills, this new information does not change the conclusions of the 2012-2017 WPA/CPA Multisale EIS

and WPA 233/CPA 231 Supplemental EIS because such a low-probability catastrophic event is unlikely 

to occur and because BOEM has already considered the potential irreversible effects to marshes, such as 

erosion and permanent loss, in Appendix B (Section 5.2.2.6) of the 2012-2017 WPA/CPA Multisale EIS.

As identified in the resource analyses above and in Chapter 4.2.1.4 of the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, BOEM has identified incomplete or 

unavailable information regarding wetlands in the CPA. This incomplete or unavailable information may 

be relevant to reasonably foreseeable significant adverse effects. BOEM has determined that the 

information is not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for wetlands presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented above. No 

new significant information was discovered that would alter the impact conclusion for wetlands presented 

in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The analysis and 

potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

4.1.1.5. Seagrass Communities

BOEM has reexamined the analysis for seagrass communities presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

seagrass communities presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS.

A detailed description of seagrass communities and the full analyses of the potential impacts of 

routine activities and accidental events associated with a CPA proposed action are presented in Chapter 

4.2.1.5 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 

4.2.1.5 of the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution 

to the cumulative impacts is presented below. The following information is a summary of the resource 

description incorporated from the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. Any new information that has become available since those documents were 

published is presented below.

Submerged vegetation distribution and composition depend on an interrelationship among a number 

of environmental factors that include water temperature, depth, turbidity, salinity, turbulence, and 

substrate suitability (Kemp, 1989; Onuf, 1996; Short et al., 2001). Marine seagrass beds generally occur 

in shallow, relatively clear, protected waters with sand bottoms (Short et al., 2001). Freshwater 

submerged aquatic vegetation (SAV) occurs in the low-salinity waters of coastal estuaries (Castellanos 

and Rozas, 2001). Seagrasses and freshwater SAV’s provide important nursery and permanent habitat for 

sunfish (Lepomis sp.), killifish (Fundulus sp.), shrimp (Penaeidae and Palaemonidae), crabs (Callinectes

sp. and Xanthidae), drums and seatrout (Sciaenidae), flounder (Paralicthys sp.), and several other nekton 

species, and they provide a food source for species of wintering waterfowl and megaherbivores (Rozas 

and Odum, 1988; Rooker et al., 1998; Castellanos and Rozas, 2001; Heck et al., 2003; Orth et al., 2006). 

In the northern Gulf of Mexico from south Texas to Mobile Bay, seagrasses occur behind barrier islands 

in bays, lagoons, and coastal waters (Figure 4-4 of the 2012-2017 Multisale EIS), while SAV’s occur in 

the upper freshwater regions of estuaries and rivers (Onuf, 1996; Castellanos and Rozas, 2001; Handley 

et al., 2007).
4-48 Central Planning Area Lease Sales 235, 241, and 247 EIS

Impacts of Routine and Accidental Events

The potential routine impact-producing factors on seagrass communities of the CPA are the 

construction of pipelines, canals, navigation channels, and onshore facilities; maintenance dredging; and 

vessel traffic (e.g., propeller scars). A detailed impact analysis of the routine impacts of OCS activities 

associated with a CPA proposed action on seagrass communities can be found in Chapter 4.2.1.5.2 of the 

2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.5 of the WPA 

233/CPA 231 Supplemental EIS.

Routine OCS activities in the CPA that may impact seagrasses are not expected to significantly 

increase as a result of the proposed action because minimal action-associated nearshore activities and 

infrastructure are expected. There is only one potential pipeline landfall and only a minor increase in 

vessel traffic (2%) projected as a result of the CPA proposed action. Any work in and around submerged 

aquatic vegetation, especially seagrasses, is highly regulated by multiple State and Federal programs; as 

such, considerable mitigation is expected to reduce the undesirable effects on submerged vegetation beds. 

This includes the rerouting of pipelines, avoidance of vegetated communities, use of turbidity curtains, or 

the use of directional boring techniques. Local outreach programs decrease the occurrence of prop 

scarring in grass beds; however, channels utilized by OCS vessels are typically away from exposed 

submerged vegetation beds. Because of these requirements and implemented programs, along with the 

beneficial effects of natural flushing (e.g., from winds and currents), any potential effects from routine 

OCS activities on submerged vegetation in the CPA are expected to be short term, localized, and not 

significantly adverse.

Accidental disturbances resulting from a CPA proposed action, including oil spills and blowouts, 

have the potential to change community structure, decrease growth rates, cause death, or cause a decline 

in ecological services by seagrass communities of the CPA. A detailed impact analysis of the accidental 

impacts that may be associated with proposed CPA Lease Sales 235, 241, and 247 on seagrass 

communities can be found in Chapter 4.2.1.5.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated 

information is provided in Chapter 4.2.1.5 of the WPA 233/CPA 231 Supplemental EIS.

Accidental events possible with a CPA proposed action that could adversely affect submerged 

vegetation beds include nearshore and inshore spills connected with the transport and storage of oil. The 

greatest possibility of a spill is from a vessel accident or pipeline rupture; however, because pipelines can 

be shut off, ships carry limited amounts of oil, and response vessels can more easily access nearshore 

areas, it is expected that the resulting spill would be smaller and shorter than an uncontrolled offshore 

spill or blowout, resulting in short-term and localized impacts. Additionally, extreme tides and/or wind 

events are the only time that submerged aquatic vegetation is typically exposed to the air-water interface 

where most oil would be floating. As such, seagrasses are not expected to come in direct contact with 

surface oil; however, if oil did come in contact with seagrasses, the results could range from the sloughing 

of epiphytes to death. Offshore oil spills that occur in a CPA proposed action area are less likely to 

contact seagrass communities than are inshore spills. If the temporal and spatial duration of the spill is 

big enough, an offshore spill could affect submerged vegetation communities, although the oil would be 

substantially more weathered and spills would be outside the barrier islands, peninsulas, sand spits, and 

currents that protect most seagrass beds. An offshore spill would result in more sinking oil (e.g., tarballs 

and patties) than an inshore spill that could become entrained within seagrass root and leave complex near 

the seafloor. Cleanup efforts in response to a spill can also negatively impact submerged aquatic 

vegetation. Close monitoring and restrictions on the use of bottom-disturbing equipment and vessel 

operations in and around SAV’s would be needed to avoid or minimize those impacts. The floating 

nature of nondispersed crude oil, the regional microtidal range, the dynamic climate with mild 

temperatures, and the amount of microorganisms that consume oil would alleviate prolonged effects on 

submerged vegetation communities. It has been shown that short-term effects from an offshore spill 

could have little impact on specific seagrass communities. Fodrie and Heck (2011) found that, after the 

Deepwater Horizon oil spill, there were few immediate or catastrophic changes in seagrass-based nekton 

communities in Alabama, Florida, and Louisiana seagrass communities. Also, safety and spill-prevention 

technologies are expected to continue to improve and will decrease detrimental effects to submerged 

vegetation from a CPA proposed action. Overall, impacts to submerged vegetation from an accidental 

event related to a CPA proposed action are expected to be minimal due to the distance of most activities 

from the submerged vegetation beds and because the likelihood of an accidental event of size, location, 

and duration reaching submerged vegetation beds remains small.
Description of the Environment and Impact Analysis 4-49

Summary and Conclusion

BOEM has reexamined the analysis for seagrass communities presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for 

seagrass communities presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated information provided in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

Of all of the activities in the cumulative scenario found in Chapter 3.3, dredging, oil spills/pipelines, 

hydrological changes due to channelization, and storm events present the greatest threat of impacts to 

submerged vegetation communities.

OCS Oil- and Gas-Related Impacts 

The OCS activities that threaten submerged vegetation are infrastructure construction, pipelines, 

dredging, and oil spills including low-probability catastrophic spills (Appendix B). Infrastructure 

emplacement, such as a pipeline landfall, and the vessel activity and dredging associated with the 

emplacement may affect submerged vegetation beds. From 2012 to 2051, offshore oil and gas activities 

are projected to generate 0-1 pipeline landfalls per CPA lease sale; this is equivalent to less than 1 

pipeline landfall a year for a CPA proposed action. Pipelines are heavily regulated and permitted, and 

they are likely to be required to be sited away from submerged vegetation. Although, submerged 

vegetation communities can be scarred by boat anchors, keels, and propellers, and by equipment 

associated with seismic surveys conducting routine OCS oil and gas activities (Sargent et al., 1995; 

Dunton et al., 1998), in general, channels used by OCS vessels are away from exposed submerged 

vegetation beds.

In support of inshore petroleum development, the oil and gas industry performs dredging that impacts 

lower-salinity submerged vegetation. Generally, dredging generates the greatest overall OCS oil- and 

gas-related risk to submerged vegetation by uprooting and burying plants, decreasing oxygen in the water 

and reducing water clarity in an area. Mitigation may be required to reduce undesirable impacts of 

dredging to submerged vegetation. The most effective mitigation for direct impacts to submerged 

vegetation beds is avoidance, but there are other mitigation techniques in place to lessen the effects of 

unavoidable disturbances. Because vessel traffic is only expected to increase by 2 percent as a result of a 

CPA proposed action, there are expected to be few if any new channels dredged or widened specifically 

for a proposed action. Additionally, dredging is expected only in areas that do not support submerged 

vegetation beds. The OCS oil- and gas-related dredging and vessel traffic related to a CPA proposed 

action remains a subset of all dredging (refer to the “Non-OCS Oil- and Gas-Related Impacts” section 

below) and traffic issues from all sources in the Gulf.

Other OCS activities that could cause adverse effects to submerged vegetation are accidental oil-spill 

events. These are generally rare and small-scale, but they do add to the possible cumulative damage to 

submerged vegetation ecosystems. Inshore oil spills generally present a greater risk of adversely 

impacting submerged vegetation and seagrass communities than do offshore spills. Inshore spills would 

be expected to be smaller in size than offshore spills but, because the oil from an inshore spill would not 

be weathered, it could be potentially more toxic. Because of the subtidal life history, microtides in the 

Gulf of Mexico, and the hydrophobic nature of oil, little to no direct permanent mortality of seagrass beds 

is expected as a result of oil-spill occurrences (Zieman et al., 1984; Gab-Alla, 2000). The only exception 

to this is during an extreme low-tide event when some of the shallower seagrasses may be exposed below 

the air-water interface as water levels drop and oil coats the plants. These tides are not normal and 

typically occur during winter or spring tides or when a low tide coincides with an offshore wind. There 

has been no documented occurrence of extensive oiling of seagrasses in the Gulf of Mexico except during 

the Ixtoc I spill. During this spill, damage to seagrass meadows was temporary (Baca et al., 1982; 

Tunnell and Dokken 1980); however, outside the Gulf of Mexico, changes in biomass, cover, and species 
4-50 Central Planning Area Lease Sales 235, 241, and 247 EIS

composition of seagrass communities have been observed post-spills (Nievales, 2009). Epifauna could 

also be exposed to oil during one of these events and a high mortality rate could be expected; however, 

many of these species can rapidly repopulate an area once the vegetation returns. Oil spills alone would 

typically have little impact on submerged vegetation beds and associated epifauna because nondispersed 

oil floats and because of the microtidal range of the Gulf of Mexico.

During and after a spill event, the response effort can cause significant scarring and trampling of 

submerged vegetation beds with increased vessel traffic in the area. Preventative measures (booms, 

berms, and diversions) can alter water hydrology and salinity, which could harm the beds and their 

associated communities. There is a small probability of an offshore spill contacting beds, and inshore 

spills would be small and short-lived; oil exposure is not expected to increase over current levels with a 

CPA proposed action. In the rare event of a large spill such as the Deepwater Horizon oil spill, there 

would be similar impacts to submerged vegetation as a smaller spill, just over a larger area and over a 

longer time period (Appendix B). 

Non-OCS Oil- and Gas-Related Impacts

Other influences on submerged vegetation can include non-OCS oil- and gas-related dredging and 

vessel traffic, changes in salinity and nutrient inputs (Waycott et al., 2009; Orth et al., 2006), and storm 

events. Maintenance dredging of navigation channels may also affect submerged vegetation beds by 

increasing turbidity and allowing larger vessels with larger wakes access to more areas. This dredging is 

necessary for a variety of reasons, including State onshore oil and gas activities and commercial barging. 

The COE performs maintenance dredging of navigation channels to help sustain the outcome of the 

original dredging event. This generally occurs every 2-5 years despite a CPA proposed action. Impacts 

on seagrasses from dredging activities can also result from of the installation of new channels; however, 

there are no new channels expected to be created as a result of a CPA proposed action. Scarring of 

seagrass beds by other vessels (e.g., support vessels for State oil and gas activities, commercial shipping, 

cruise ships, fishing vessels, and recreational watercraft) is an increasing concern in coastal areas, 

particularly along the Texas coast (Dunton et al., 1998; State of Texas, Parks and Wildlife Department, 

1999; Pulich and Onuf, 2007). Scarring most commonly occurs in water depths less than 2 m (~6 ft) as a 

result of boats operating in too shallow water (Zieman, 1976; Sargent et al., 1995; Dunton et al., 1998). 

Consequently, their propellers, and occasionally their keels, plow through vegetated bottoms, tearing up 

roots, rhizomes, and whole plants, leaving a furrow that is devoid of submerged vegetation (Zieman, 

1976; Dawes et al., 1997). A few State and local governments have instituted management programs that 

have resulted in reduced scarring, which could decrease bed patchiness. For example, the State of Florida 

Seagrass Outreach Partnership consists of citizens, researchers, law enforcement officers, and marine 

resource managers and was created to reduce boating impacts to seagrass meadows through education. 

The State of Texas has also enacted House Bill 3279, which makes it illegal to uproot seagrasses in all 

coastal waters.

Saltwater intrusion resulting from river channelization and canal dredging is a major cause of coastal 

habitat deterioration (including submerged vegetation communities) (Boesch et al., 1994). Productivity 

and species diversity associated with SAV habitat in the coastal marshes of the GOM are greatly reduced 

by saltwater intrusion (Stutzenbaker and Weller, 1989; Lirman et al., 2008). Due to increased salinities 

farther up the estuaries, some salt-tolerant species of submerged vegetation (including seagrasses) are able 

to populate areas farther inland and outcompete the dominant submerged aquatic vegetation species 

(Longley, 1994). Large shifts in salinities can decrease seagrass and submerged aquatic vegetation 

populations and decrease their ecological function for juvenile fishes and invertebrates. Increased 

nutrients from diversions, runoffs, or flooding events can cause eutrophication in local waters. This can 

increase phytoplankton and epiphytic growth, which will shade and decrease submerged vegetation 

(Larkum et al., 2006; Orth et al., 2006). This relationship is complex and depends on multiple 

environmental factors.

Tropical cyclone activity in the Gulf of Mexico (USDOC, NOAA, 2005) is also common and can 

have a significant impact on seagrasses and submerged aquatic vegetation. Storms can remove or bury 

submerged beds of seagrasses and the barrier islands that protect them from storm surges. A seagrass bed 

already weakened due to other anthropogenic impacts could be substantially more susceptible to damage 

from a storm event. Hurricanes can result in the burial of seagrasses and the eroding of channels through 

seagrass beds. Burial occurs when storm-generated waves wash sand from the seaward side of barrier 
Description of the Environment and Impact Analysis 4-51

islands and deposit it on the shallow seagrass-containing areas on the back side of the islands. Having 

evolved in an environment where burial occurs regularly, many seagrasses are equipped to rapidly extend 

vertical rhizomes to recover from burial (Marba and Duarte 1994, Marba et al. 1994, Cabaço et al., 2008). 

Storms can also erode new passes through the islands, removing all the seagrass in its path (Michot and 

Wells, 2005). Over time, seagrass can recolonize the new sand flats on the shoreward side, and the 

natural processes of sand movement rebuild the islands. Overall, the effects of hurricanes on seagrass 

beds are highly variable and can range from significant changes in seagrass community quality and 

composition (Maiaro, 2007) to no substantial effects (Byron and Heck 2006). However, combined with 

other stressors (Orth et al., 2006), impacted seagrass beds may fail to recover after a storm event.

Summary and Conclusion

In general, a CPA proposed action would cause a minor incremental contribution to impacts on 

submerged vegetation from dredging, pipeline installations, potential inshore oil spills, and boat scarring. 

Dredging and shading generate the greatest overall risk to submerged vegetation, while naturally 

occurring hurricanes cause direct damage to beds. The implementation of proposed lease stipulations and 

mitigation policies currently in place, the small probability of an oil spill, and because flow regimes are 

expected to change further reduce the incremental contribution of stress from a CPA proposed action to 

submerged vegetation.

Unavailable information on the effects to submerged vegetation from the Deepwater Horizon

explosion, oil spill, and response (and thus changes to the submerged vegetation baseline in the “Affected 

Environment” (Chapter 4.2.1.5.1 of the 2012-2017 WPA/CPA Multisale EIS) makes an understanding of 

the cumulative effects less clear. BOEM concludes that the unavailable information from these events 

may be relevant to foreseeable significant adverse impacts to submerged vegetation. Relevant data on the 

status of submerged vegetation beds after the Deepwater Horizon explosion, oil spill, and response may 

take years to acquire and analyze, and impacts from the Deepwater Horizon explosion, oil spill, and 

response may be difficult or impossible to discern from other factors. Therefore, it is not possible for 

BOEM to obtain this information within the timeline contemplated in the NEPA analysis of this 

Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable 

information, BOEM’s subject-matter experts have used available scientifically credible evidence in this 

analysis and based it upon accepted methods and approaches. Nevertheless, BOEM believes that 

incomplete or unavailable information regarding the effects of the Deepwater Horizon explosion, oil spill, 

and response on submerged vegetation is not essential to a reasoned choice among alternatives in the 

cumulative effects analysis. In light of this, the incremental contribution of a CPA proposed action 

remains minor compared with the cumulative effects of other factors, including dredging, hurricanes, and 

vessel traffic.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of various printed and Internet sources was conducted for any recent information published 

regarding coastal submerged vegetation. Sources investigated include BOEM, USDOC/NOAA, the 

USGS National Wetlands Research Center, the USGS Gulf of Mexico Integrated Science Data 

Information Management System, Seagrass Watch, Gulf of Mexico Alliance, State environmental 

agencies, USEPA, and coastal universities. Other websites from scientific publication databases 

(including Science Direct, SCIRUS, Google Scholar, Elsevier, Pro Quest, and JSTOR) were checked for 

new information using general Internet searches based on major themes. New information available that 

is relevant to a CPA proposed activity includes information related to responses of seagrass species that 

were potentially exposed to Macondo oil. Moody et al. (2013) found that the recruitment of many species 

of invertebrates in an Alabama marsh was not negatively impacted by the Macondo oil spill. Although 

focused on the marsh, this study is important because many of the species found in the marsh are also 

found in the seagrass. Dubinsky et al. (2013) did note that exposure to Macondo-related sediments that 

were contaminated with PAH’s resulted in Gulf killifish (Fundulus grandis) having multitissue 

molecular, genomic, and developmental responses, suggesting that oil exposure could result in 

population-level effects. The Gulf killifish is typically found in marsh habitats, but it can be found in 

seagrass habitats (Schofield and Fuller, 2013). Because of the cosmopolitan distribution of the Gulf 
4-52 Central Planning Area Lease Sales 235, 241, and 247 EIS

killifish, exposure at a level to have more than a localized response would be in the case of a lowprobability catastrophic spill.

There remains uncertainty regarding the impacts of the Deepwater Horizon explosion, oil spill, and 

response on submerged vegetation. For submerged vegetation in Louisiana, Mississippi, and Alabama, 

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

through the NRDA process may be essential to a reasoned choice among alternatives for the reasons 

stated herein and in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. 

Nevertheless, the ongoing research on submerged vegetation after the Deepwater Horizon explosion, oil 

spill, and response is being conducted through the NRDA process. These research projects may be years 

from completion, and data and conclusions have not been released to the public. Regardless of the costs 

involved, it is not within BOEM’s ability to obtain this information from the NRDA process within the 

timeline contemplated in the NEPA analysis of this Supplemental EIS. In light of this incomplete and 

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

available and applied it using scientifically accepted methodology.

4.1.1.6. Live Bottoms (Pinnacle Trend and Low Relief) 

BOEM has reexamined the analysis for live bottoms (both Pinnacle Trend and Low Relief) presented 

in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS based on the 

additional information presented below. No new significant information was discovered that would alter 

the impact conclusion for live bottoms presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS.

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

CPA proposed action are presented in Chapter 4.2.1.6 of the 2012-2017 WPA/CPA Multisale EIS, and

updated information is presented in the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s 

incremental contribution to the cumulative impacts is presented below. The following information is a 

summary of the resource description incorporated from the 2012-2017 WPA/CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS. Any new information that has become available since those 

documents were published is presented below.

Impacts of Routine and Accidental Events

The potential routine impact-producing factors on live bottoms of the CPA are anchoring, 

infrastructure emplacement, drilling effluent and produced-water discharges, and infrastructure removal. 

These disturbances have the potential to disrupt and alter the environmental, commercial, recreational, 

and aesthetic values of live bottoms in the CPA. A detailed impact analysis of the routine impacts of 

OCS activities associated with a CPA proposed action on live bottoms can be found in Chapters 

4.2.1.6.1.2 and 4.2.1.6.2.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.6 of the WPA 233/CPA 231 Supplemental EIS. Below is a summary of that 

information.

The live bottoms (Pinnacle Trend and low-relief habitats) of the CPA could be adversely impacted by 

oil and gas activities resulting from a CPA proposed action in the absence of the proposed Live Bottom 

(Pinnacle Trend) Stipulation, which distances bottom-disturbing activity 30 m (100 ft) from pinnacles, 

and by case-by-case reviews of permit applications for wells, pipelines, and structure removals. There is 

a Live Bottom (Low Relief) Stipulation that is applied to leases in live bottom low-relief blocks with 

water depths of 100 m (328 ft) or less in the EPA and northeast corner of the CPA; however, none of 

these blocks are offered for lease in these proposed CPA lease sales; therefore, this stipulation will not be 

applied. BOEM’s case-by-case reviews offer protection for live bottoms that occur outside of the 

identified live bottom low-relief blocks and do not permit bottom-disturbing activity within 30 m (100 ft) 

a live bottom.

Structure or pipeline emplacement and anchoring of pipeline barges, drilling rigs, and service vessels 

could damage Pinnacle features and low-relief live bottoms. Organisms on live bottoms could be crushed 

and hard features destroyed by bottom disturbance. Such habitat damage may take a long time to 

repopulate with live bottom communities. Distancing bottom-disturbing activity 30 m (100 ft) from live 

bottoms eliminated the possibility of placing a structure or anchor on a live bottom.
Description of the Environment and Impact Analysis 4-53

Oil and gas operations discharge cuttings with some adhered drilling mud that generates turbidity, 

potentially smothering benthos near the drill sites. Deposition of drilling muds and cuttings near the 

Pinnacle Trend and low-relief areas would not greatly impact the biota of the live bottoms because the 

biota surrounding the live bottom features in or near the CPA are adapted to turbid (nepheloid) conditions 

and high sedimentation rates associated with the outflow of the Mississippi River (Gittings et al., 1992a). 

The pinnacles themselves and many live bottoms are coated with a veneer of sediment. Regional surface 

currents and water depth would largely dilute any oil- and gas-related effluent. Additional deposition and 

turbidity caused by a nearby well are not expected to adversely affect the live bottom habitat because such 

drilling muds and cuttings would be dispersed upon discharge. For example, mud contaminants measured 

in the Pinnacle Trend region reached background levels within 1,500 m (4,921 ft) of the discharge point 

(Shinn et al., 1993). Toxic impacts on benthos, however, are limited to within 100-200 m (328-656 ft) of 

a well (Montagna and Harper, 1996; Kennicutt et al., 1996), and NPDES permit requirements limit 

discharge, limiting toxicity levels. The drilling of a well, therefore, would have minimal impacts on live 

bottom features due to distancing requirements and local turbidity levels.

The toxicity of produced waters has the potential to adversely impact the live bottom organisms; 

however, the proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews would prevent 

the placement of oil and gas facilities within 30 m (100 ft) of a live bottom. In addition, the live bottom 

low-relief blocks are not currently for lease, and therefore, they will be distanced from discharges as well. 

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

live bottom features.

Platform removals have the potential to impact nearby habitats; however, the Live Bottom (Pinnacle 

Trend) Stipulation and BOEM’s case-by-case reviews before platform installation and removal prevent 

platforms from being placed within 30 m (100 ft) of any live bottom. This distancing requirement will 

separate sensitive low-relief habitats from blasts. Benthic organisms on live bottoms should also have 

limited impact because they are resistant to blasts, tolerant of turbidity, can physically remove some 

suspended sediment, and may be located above or be tall enough to withstand limited sediment 

deposition. Distancing would also help prevent live bottoms from being smothered by disturbed sediment 

as it settles out of the water column.

The Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews of permit applications would 

prevent most of the potential impacts on live bottoms from bottom-disturbing activities (structure 

emplacement, anchoring, and removal) and operational discharges associated with a CPA proposed action 

by distancing activities 30 m (100 ft) from live bottoms. The distancing requirement also allows for the 

dilution of operational discharges (drill cuttings and adhered muds as well as produced waters), and 

USEPA’s discharge regulations and permits limit toxicity of discharges. The natural turbidity of the 

environment also limits the impacts of suspended sediment and deposition on these habitats. Impacts on 

live bottom habitat as a result of OCS oil and gas operational discharges is, therefore, minimal.

Accidental disturbances resulting from a CPA proposed action, including oil spills and blowouts, 

have the potential to disrupt and alter the environmental, commercial, recreational, and aesthetic values of 

live bottoms of the CPA. A detailed impact analysis of the accidental impacts that may be associated 

with proposed CPA Lease Sales 235, 241, and 247 on live bottoms can be found in Chapters 4.2.1.6.1.3 

and 4.2.1.6.2.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.6 of the WPA 233/CPA 231 Supplemental EIS. Without the Live Bottom (Pinnacle Trend) 

Stipulation and case-by-case reviews of permit applications, live bottoms could be impacted by accidental 

events. Live bottom features represent a small fraction of the continental shelf area in the CPA. The 

small portion of the seafloor covered by the Pinnacle Trend and the fact that low-relief features are widely 

dispersed, combined with the probable random nature of oil-spill locations, serves to limit the extent of 

damage from any given oil spill to live bottoms.

The proposed Live Bottom (Pinnacle Trend) Stipulation (Chapter 2.4.1.3.2) and case-by-case 

reviews of permit applications would prevent most of the potential impacts from oil and gas operations, 

including accidental oil spills and blowouts, on the biota of live bottoms by distancing activities that 

could result in oil spills and blowouts 30 m (100 ft) from the features. Also, note that none of the live 

bottom low-relief blocks are included in the area to be offered in a CPA proposed action. However, 

operations that occur in blocks adjacent to live bottom habitat may affect live bottom features.

In a subsurface spill or blowout situation, it would be expected that the majority of released oil would 

rise to the surface and that the most heavily oiled sediments would likely be deposited before reaching 
4-54 Central Planning Area Lease Sales 235, 241, and 247 EIS

live bottom features. However, operations outside the buffer zones created by distancing activities from 

features could have some impact on live bottom features.

The depth below the sea surface to which many live bottom features rise helps to protect them from 

surface oil spills. Some Pinnacles may rise to within 40 m (130 ft) of the sea surface; however, many 

features have much less relief or are in deeper water depths. Any oil that might contact pinnacle features 

would probably be at low concentrations because the depth to which surface oil can mix down into the 

water column is less than the peak of the tallest pinnacles, and this would result in little effect to these 

features. Low-relief features are also far below the water’s surface, except some in shallow EPA waters, 

and are far from any area available for lease. Because the concentration of oil becomes diluted as it 

physically mixes with the surrounding water and as it moves into the water column, any oil that might be 

driven to 10 m (33 ft) or deeper would probably be at concentrations low enough to reduce impact to 

these features. Any features in water shallower than 10 m (33 ft) would be located far from the source of 

activities in a CPA proposed action. Therefore, concentrated oil should not reach live bottom features, 

and any impacts from diluted oil would be sublethal.

A subsurface spill or plume may impact sessile biota of live bottom features. Oil or dispersed oil may 

cause sublethal impacts to benthic organisms if a plume reaches these features. Impacts may include loss 

of habitat, biodiversity, and live coverage; change in community structure; and failed reproductive 

success. The Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews of permit applications 

would limit the potential impact of such occurrences by keeping the sources of such adverse events 

geographically removed from the sensitive biological resources of live bottom features. Distancing OCS 

activity allows for oil to mix with the surrounding water and become less concentrated by the time it 

reaches a feature, thus reducing toxicity.

Suspended sediment and oil adhered to sediment in the water column as a result of a blowout may 

impact benthic organisms. However, because the Live Bottom (Pinnacle Trend) Stipulation and case-bycase reviews of permit applications distances petroleum-producing activity 30 m (100 ft) from live bottom 

features, the heaviest sediment concentrations would fall out of suspension and the suspended sediment 

would disperse, resulting in reduced turbidity and sedimentation near the sensitive features. Many of the 

live bottom organisms of the CPA are located within the influence of the Mississippi River plume and are 

more tolerant of turbidity and sedimentation, allowing them to withstand a degree of these impacts. Many 

also have the ability to rid themselves of sediment through ciliary action and mucus shedding.

The proposed Live Bottom (Pinnacle Trend) Stipulation, if applied, and case-by-case reviews of 

permit applications would assist in preventing most of the potential impacts on live bottom communities 

from blowouts, surface and subsurface oil spills, and the associated effects by increasing the distance of 

such events from the live bottoms. In addition, because no live bottom low-relief blocks are included in a 

CPA proposed action, most live bottom features are distanced from oil-producing activity. It would be 

expected that the majority of oil released from a blowout would rapidly rise to the surface and that the 

most heavily oiled sediments would likely be deposited on the seafloor before reaching the live bottoms. 

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 spill 

would reach the biota of a live bottom, the effects would be primarily sublethal and impacts would be at 

the community level. Any turbidity, sedimentation, and oil adsorbed to sediments would also be at low 

concentrations by the time the live bottoms were reached, also resulting in sublethal impacts. Impacts 

from an oil spill on live bottoms are lessened by the distance of the spill to the features, the depth of the 

features, and the currents that surround the features. In the event that oil from a subsurface spill reached 

an area containing coral cover in lethal concentrations, the recovery could take in excess of 10 years 

(Fucik et al., 1984).

Summary and Conclusion

BOEM has reexamined the analysis for live bottoms presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented above. No 

new significant information was discovered that would alter the impact conclusion for live bottoms 

presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The 

analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the 

WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.
Description of the Environment and Impact Analysis 4-55

Cumulative Impacts

Background/Introduction 

The proposed Live Bottom (Pinnacle Trend) Stipulation is assumed to be in effect for this cumulative 

analysis as well as for the case-by-case reviews of permit applications to prevent impacts to identified live 

bottoms (low and high relief). Details on the Live Bottom (Pinnacle Trend) Stipulation can be found in 

Chapter 2.3.1.3.2 of this Supplemental EIS and in Chapter 2.4.1.3.2 of the 2012-2017 WPA/CPA 

Multisale EIS. The continued application of this proposed stipulation and case-by-case permit reviews 

would prevent any direct adverse impacts on the biota of the live bottoms, i.e., impacts potentially 

generated by oil and gas operations. The cumulative impact from routine oil and gas operations includes 

effects resulting from a CPA proposed action, as well as those resulting from past and future OCS oil and 

gas leasing. These operations include anchoring, structure emplacement, muds and cuttings discharge, 

effluent discharge, blowouts, oil spills, and structure removal. Potential non-OCS oil- and gas-related 

factors include vessel anchoring, import tankering, heavy storms and hurricanes, commercial fishing, and 

recreational scuba diving.

OCS Oil- and Gas-Related Impacts 

Mechanical damage, such as anchoring, is considered to be a catastrophic threat to the biota of live 

bottoms. The continued application of the proposed Live Bottom (Pinnacle Trend) Stipulation and caseby-case reviews preclude anchoring on live bottoms by OCS oil- and gas-related operations. Detrimental 

impacts would result if oil and gas operators anchored pipeline barges, drilling rigs, and service vessels, 

or if they placed structures on live bottoms (Lissner et al., 1991; Dinsdale and Harriott, 2004). The 

proposed Live Bottom (Pinnacle Trend) Stipulation restricts these activities within 30 m (100 ft) of a 

Pinnacle feature, thus preventing adverse impacts on benthic communities of these features. In addition, 

case-by-case reviews would identify live bottoms in the area of activity and prevent bottom-disturbing 

activity within 30 m (100 ft) of a live bottom.

The USEPA, through its NPDES discharge permit, enacts mitigating measures on discharges. 

Drilling fluids can be moderately toxic to marine organisms (the more toxic effluents are not allowed to 

be discharged under NPDES permits), but their effects are restricted to areas closest to the discharge 

point, thus preventing contact with the biota of live bottoms (Montagna and Harper, 1996; Kennicutt 

et al., 1996). Small amounts of drilling effluent in low concentrations may reach a live bottom from wells 

beyond the 30-m (100-ft) buffer; however, these amounts, if measurable, would be extremely small and 

would be restricted to small areas, with little effect on the biota.

The proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews of permit 

applications protect live bottom features by mandating a physical distance from drilling activities. 

Drilling fluid plumes are rapidly dispersed on the OCS; approximately 90 percent of the material 

discharged in drilling a well (cuttings and drilling fluid) settles rapidly to the seafloor, while 10 percent 

forms a plume of fine mud that drifts in the water column (Neff, 2005). Any drilling material that may 

reach coral can be removed by the coral using tentacles and mucus secretion, and it can be physically 

removed by currents that can help shed the mucus-trapped particles from the coral (Shinn et al., 1980; 

Hudson and Robbin, 1980).

With the inclusion of the proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case 

reviews, no discharges of effluents, including produced water, would take place within 30 m (100 ft) of a 

live bottom. This distancing, combined with USEPA’s discharge regulations and permits, should 

eliminate the threat of discharges reaching and affecting the biota of a live bottom. The impacts that these 

discharges could cause would be primarily sublethal damages that could lead to a possible disruption or 

impairment of a few elements at a local scale, but no interference to the general ecosystem performance 

should occur.

Impacts on the live bottoms could occur as a result of OCS oil- and gas-related spills or spills from 

import tankering. Due to dilution and the depths of the crests of the Pinnacle and other live bottom 

features, discharges should not reach the live bottom features in sufficient concentrations to cause 

impacts. Tanker accidents would result in surface oil spills, which generally do not mix below a depth of 

10-20 m (33-66 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002). The 

limited depth of mixing should protect most live bottoms, very few of which rise to within 20 m (66 ft) of 

the sea surface, except those in shallow waters of the EPA, which are extremely far from a CPA proposed 
4-56 Central Planning Area Lease Sales 235, 241, and 247 EIS

action. Any dispersed surface oil from a tanker spill that may reach the benthic communities of live 

bottoms in the Gulf of Mexico would be expected to be at very low concentrations (<1 ppm) (McAuliffe 

et al., 1981a and 1981b; Lewis and Aurand, 1997). Such concentrations would not be life threatening to 

larval or adult stages based on experiments conducted with coral (Lewis, 1971; Elgershuizen and De 

Kruijf, 1976; Knap, 1987; Wyers et al., 1986; Cohen et al., 1977) and observations after oil spills 

(Jackson et al., 1989; Guzmán et al., 1991). Any dispersed or physically mixed oil in the water column 

that comes in contact with corals, however, may evoke short-term negative responses by the organisms, 

such as reduced feeding and photosynthesis or altered behavior (Wyers et al., 1986; Cook and Knap, 

1983; Dodge et al., 1984).

Potential blowouts and low-probability catastrophic spills (Appendix B) could impact the biota of the 

live bottoms. Based on the proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews, 

few blowouts or low-probability catastrophic spills, if any, would reach the live bottoms. The proposed 

stipulation and BOEM’s policy applied during case-by-case reviews creates a 30-m (100-ft) buffer zone 

around live bottoms; this buffer zone would protect the live bottoms from direct impacts by damaging 

amounts of suspended sediment from a seafloor blowout. Most of the oil from a seafloor blowout, even a 

catastrophic one, would rise to the surface, but some of it may be entrained in the water column as a 

subsea plume. Oil in a subsea plume could be carried to a live bottom. The resulting level of impacts 

depends on the concentration of the oil when it contacts the habitat. The farther the blowout is from the 

live bottom, the more dispersed the oil and sediment will become, reducing the possible impacts. If oil 

were to contact the live bottoms, the impacts may include loss of habitat, biodiversity, and live coverage; 

change in community structure; and failed reproductive success. In the highly unlikely event that oil from 

a subsurface spill could reach a coral-covered area in lethal concentrations, the recovery of this area could 

take in excess of 10 years (Fucik et al., 1984).

The cumulative impact of possible oil spills, along with the Deepwater Horizon explosion, oil spill, 

and response, is not anticipated to affect the overall live bottom habitat. The Live Bottom (Pinnacle 

Trend) Stipulation and case-by case reviews of permit applications would not allow wells to be drilled 

within 30 m (100 ft) of a live bottom, separating the habitat from the worst of the sediment deposition of a 

blowout and allowing most of the oil to rise to the sea surface without contacting live bottoms. If oil is 

released near a live bottom and concentrated or dispersed oil is entrained in the water column, it could 

contact nearby live bottom habitat with serious detrimental effects. Habitats receiving high 

concentrations of oil could take 10 or more years to recover (Fucik et al., 1984). However, since subsea 

plumes travel directionally with water currents, only live bottom habitats directly in the path of the plume 

would be affected. Therefore, the acute impacts of any large-scale blowout would likely be limited in 

scale, and any additive impacts of several blowouts should only impact small areas on an acute level, with 

possible sublethal impacts occurring over a larger area.

Platforms will be removed from the OCS Program each year; some may be in the vicinity of live 

bottoms (Table 3-2). However, the proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case 

permit application reviews prevents the installation of platforms within 30 m (100 ft) of a live bottom, 

thus reducing the potential for impact from platform removal. The explosive removals of platforms are 

far enough away to prevent impacts to the biota of the live bottoms.

Non-OCS Oil- and Gas-Related Impacts

Although the Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews of permit 

applications prohibit oil and gas leaseholders from anchoring vessels and placing structures within 30 m 

(100 ft) of a live bottom, the policy does not affect other non-OCS oil- and gas-related activities such as 

fishing, recreational scuba diving, or anchoring other vessels on or near these features. Many of the live 

bottoms are well-known fishing and diving areas. Anchoring on a live bottom by a vessel involved in any 

of these activities could damage the biota. The degree of damage would depend on the size of the anchor 

and chain (Lissner et al., 1991). Anchor damages incurred by benthic organisms may take more than 10 

years to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and Garrison, 2001).

Depending on the levels of fishing pressure exerted, recreational fishing activities that occur on live 

bottoms may impact local fish populations (refer to Chapters 4.1.1.19 and 4.1.1.20). The collecting 

activities by scuba divers on shallow live bottom features may have an adverse impact on the local biota. 

Much of the fishing on these habitats uses bottom fishing gear that may damage benthic organisms or 

may snag on the reefs and be lost. Such gear, particularly lines of varying thickness, can cut into the 
Description of the Environment and Impact Analysis 4-57

tissues of many benthic organisms during storm movement of bottom waters. Anchoring during 

recreational and fishing activities, however, would be the source of the majority of severe impacts 

incurred by the live bottoms.

Damage resulting from commercial fishing, especially bottom trawling, may have a severe impact on 

live bottoms. Bottom trawling in the Gulf of Mexico primarily targets shrimp from nearshore waters to 

depths of approximately 90 m (300 ft) (NRC, 2002). Although trawlers would not target areas with 

pinnacles or sharp relief as fishing ground, since outcrops may tangle with gear, accidental instances of 

trawling may occur near or over live bottoms, resulting in community damage. Reports indicate that 

bottom trawling activity on hard bottom substrates can overturn boulders and destroy epifaunal organisms 

(Freese et al., 1999). Large emergent sponges and anthozoans may be particularly vulnerable to trawling 

activity, as these organisms grow above the substrate and can be caught and removed by trawling activity 

(Freese et al., 1999). The recovery of corals and coralline algae may take decades to centuries and 

depends on the extent of the impact, frequency of disturbance, other natural changes that occur to the 

habitat, and the organism’s life history (NRC, 2002).

Natural events such as storms, extreme weather, and fluctuations of environmental conditions (e.g., 

nutrient pulses, low dissolved oxygen levels, seawater temperature minima, and seasonal algal blooms) 

may impact live bottom communities. Because of the depth of the Pinnacle Trend environment, waves 

seldom have a direct influence. During severe storms, such as hurricanes, large waves may reach deep 

enough to stir bottom sediments (Brooks, 1991; CSA, 1992b). These forces are not expected to be strong 

enough to cause direct physical damage to organisms living on the features. Rather, currents are created 

by the wave action that can resuspend sediments to produce added turbidity and sedimentation (Brooks, 

1991; CSA, 1992b). The animals in this region are well-adapted to the effects common to this frequently 

turbid environment (Gittings et al., 1992). Live bottom (low relief) communities, however, occur from 

the shoreline to 100 m (328 ft) of water and, because many of these features are located in shallow water, 

storm events may damage these environments. Currents are created by wave action that can resuspend 

sediments to produce added turbidity and sedimentation (Brooks, 1991; CSA, 1992b). Storms can 

physically affect shallow bottom environments, causing an increase in sedimentation, burial of organisms 

by sediment, a rapid change in salinity or dissolved oxygen levels, storm surge scouring, remobilization 

of contaminants in the sediment, and abrasion and clogging of gills as a result of turbidity (Engle et al., 

2008). Storms have also been shown to uproot benthic organisms from the sediment (Dobbs and Vozarik, 

1983), and breakage or detachment may occur as a result of storm activity (Yoshioka and Yoshioka, 

1987). Such impacts may be devastating to a benthic community.

Hypoxic conditions of inconsistent intensities and ranges also occur annually in a band that stretches 

along the Louisiana-Texas shelf each summer (Rabalais et al., 2002a). The dissolved oxygen levels of 

bottom waters in the Gulf of Mexico hypoxic zone are less than 2 ppm during part of the summer season. 

Such low concentrations are lethal to many benthic organisms and may result in the loss of some benthic 

populations. Although this is mainly a character of the Louisiana-Texas shelf, its effect could reach some 

live bottom communities in the northeast portion of the CPA.

Summary and Conclusion

Activities causing mechanical disturbance represent the greatest threat to the live bottoms. This 

would, however, be prevented by the continued application of the proposed Live Bottom (Pinnacle Trend) 

Stipulation and case-by-case reviews. Potential OCS oil- and gas-related impacts include anchoring of 

vessels and structure emplacement, operational discharges (drilling muds and cuttings, and produced 

waters), blowouts, oil spills, and structure removal.

The proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews would preclude 

mechanical damage caused by oil and gas leaseholders from impacting the benthic communities of live 

bottoms and would protect them from operational discharges by establishing a 30-m (100-ft) buffer 

around the features. As such, little impact would be incurred by the biota of the live bottoms. The 

USEPA’s discharge regulations and permits would further reduce discharge-related impacts.

Blowouts could potentially cause damage to benthic biota; however, due to the application of the 

proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case permit application reviews, 

blowouts would not reach the live bottoms and associated biota in high concentrations, resulting in little 

impact on the features. If a subsea oil plume is formed, it could contact the habitats of a live bottom. The 
4-58 Central Planning Area Lease Sales 235, 241, and 247 EIS

farther the oil source is from the live bottom, the more dilute and degraded the oil would be when it 

reaches the vicinity of the live bottom.

Oil spills can cause damage to benthic organisms when the oil contacts the organisms. The proposed 

Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews would keep sources of OCS spills at 

least 30 m (100 ft) away from the immediate biota of the live bottoms. The majority of oil released below 

the sea surface would rise and should not physically contact organisms on live bottoms. In the unlikely 

event that oil from a subsurface spill would reach the biota of a live bottom, it would be physically or 

chemically dispersed to low concentrations by the time it reached the feature, and the effects would be 

primarily sublethal. In the very unlikely event that oil from a subsurface spill reached a live bottom in 

lethal concentrations, the recovery could take in excess of 10 years (Fucik et al., 1984). Finally, in the 

unlikely event a freighter, tanker, or other oceangoing vessel related to OCS Program activities or nonOCS oil- and gas-related activities sank and proceeded to collide with the live bottoms or associated 

habitat releasing its cargo and fuel, recovery could take years to decades, depending on the extent of the 

damage. Because these events are rare in occurrence, the potential of impacts from these events is 

considered low.

Non-OCS oil- and gas-related activities could mechanically disrupt the bottom (such as anchoring, as 

previously described). Natural events such as hurricanes or storms could cause severe impacts. Impacts 

from scuba diving, fishing, and discharges or spills from tankering of imported oil could have detrimental 

effects on live bottoms. 

Overall, the incremental contribution of a CPA proposed action to the cumulative impact is negligible 

when evaluated against all other OCS oil- and gas-related and non-OCS oil- and gas-related impacts in 

the entire GOM. Where the proposed Live Bottom (Pinnacle Trend) Stipulation and case-by-case reviews 

are applied, mechanical impacts (anchoring and structure emplacement) and impacts from operational 

discharges (produced waters, drilling fluids, cuttings) or accidental discharges (oil spills, blowouts) would 

be removed from the immediate area surrounding the live bottoms. However, if the stipulation or reviews 

are not applied, acute long-term injury to live bottoms may occur as a result of a CPA proposed action.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources (NOAA’s Gulf Spill Restoration Publications website, 

NOAA’s Environmental Response Management Application [ERMA] Gulf Response website, NOAA’s 

Deepwater Horizon Archive Publications and Factsheets, the Gulf of Mexico Sea Grant Deepwater 

Horizon Oil Spill Research and Monitoring Activities Database, the RestoreTheGulf.gov website, and the 

Deepwater Horizon Oil Spill Portal), as well as recently published journal articles and Federal documents 

was conducted to determine the availability of recent information on live bottoms. The search revealed 

new information on the monitoring of corals in the GOM for impacts of oil from the Deepwater Horizon

explosion; information that is pertinent to this Supplemental EIS.

The NRDA has been investigating the possibility of impacts to mesophotic coral reefs in the Pinnacle 

Trend area as a result of the Deepwater Horizon explosion, oil spill, and response. Post oil-spill data 

(photos, video, and water quality collected by semipermeable membrane passive sampling devices) are 

being compared with pre-Deepwater Horizon data that exist from the Alabama Alps in the Pinnacle Trend 

(USDOC, NOAA, 2012a). The semipermeable membrane devices suggest that the Alabama Alps may 

have been exposed to petroleum hydrocarbons, but the pathway for impact by subsurface oil and 

dispersants has yet to be established. However, preliminary evidence indicates that planktivorous fish in 

the area have substantially decreased and mesophotic reef corals appear to be impacted (USDOC, NOAA, 

2012a). 

Toxicity tests conducted on larvae in the laboratory on two species of coral, Porites astreoides and 

Montastraea faveolata, indicated that the settlement and survival of coral larvae decreased with 

increasing water-accommodated fractions (WAF’s) of Macondo oil, the dispersant COREXIT 9500, and 

WAF’s of Macondo oil plus COREXIT 9500 (CEWAF) (Goodbody-Gringley et al., 2013). Note that 

these two species of coral are not found on live bottoms of the CPA (they are, however, found in the EPA 

and WPA) but that the results are shown as an example in oil impacts on coral settlement. The lethal 

concentration to 50 percent (LC50) of the larval population for the WAF’s of Macondo oil was 0.50 ppm 

and 0.51 ppm for P. astreoides and M. faveolata, respectively. The LC50 for COREXIT 9500 for 

P. astreoides and M. faveolata was 33.4 ppm and 19.7 ppm, while the CEWAF LC50 for these species 
Description of the Environment and Impact Analysis 4-59

was 1.84 ppm and 0.28 ppm, respectively (Goodbody-Gringley et al., 2013). It should be noted, however, 

that dispersants measured during the Deepwater Horizon explosion, oil spill, and response never reached 

chronic benchmarks in the water column (OSAT, 2010). In addition, one must be careful in using WAF 

to determine toxicity in an open system because it is based on a closed system reaching equilibrium with a 

contaminant, something that will not happen in the GOM. Therefore, the WAF and CEWAF may not be 

applicable for the GOM and could be considered a “worst-case scenario” if the entire GOM were to come 

into equilibrium with oil and dispersant inputs. Therefore, these laboratory-derived values do not 

accurately reflect field conditions.

In 2009, a petition was submitted to NMFS by the Center for Biological Diversity to list 83 additional 

species of coral under the ESA (Center for Biological Diversity, 2009). Those 83 “candidate species” 

were reviewed by NMFS. In April 2012, NMFS completed a Status Review Report and a Draft 

Management Report of the candidate species of corals, and on December 7, 2012, the “Proposed Listing 

Determinations for 82 Reef-Building Coral Species; Proposed Reclassification of Acropora palmata and 

Acropora cervicornis From Threatened to Endangered” was published in the Federal Register (Federal 

Register, 2012b). The NOAA determined that 12 of the petitioned species warranted listing as 

endangered (5 in the Caribbean and 7 in the Indo-pacific), 54 species warranted listing as threatened (2 in

the Caribbean and 52 in the Indo-Pacific), and 16 did not warrant listing under the ESA. None of these 

corals are found on live bottoms in the CPA; however, they may be found on live bottoms in the EPA and 

on topographic features in the CPA and WPA. The public comment period was extended to April 6, 

2013, and a public meeting was held on March 12, 2013 (Federal Register, 2013g). A final decision on 

the listing of these species has not been made at this time. If these proposed species are listed and if an 

action may affect the listed species or designated critical habitat, BOEM would consult with NMFS under 

section 7 of the ESA, as BOEM currently does for other listed species.

Limited data are currently available on the potential impacts of the Deepwater Horizon explosion, oil 

spill, and response on the live bottoms in the CPA. This incomplete or unavailable information may be 

relevant to reasonably foreseeable significant impacts to live bottoms. Relevant data on the status of live 

bottoms after the Deepwater Horizon explosion, oil spill, and response may take years to acquire and 

analyze. Much of these data are being developed through the NRDA process, which may take years to 

complete. Little data from the NRDA process have been made available to date. Therefore, it is not 

possible for BOEM to obtain this information within the timeline contemplated in the NEPA analysis of 

this Supplemental EIS, regardless of the cost or resources needed. BOEM has determined that this 

incomplete or unavailable information may be essential to a reasoned choice among alternatives for the 

reasons stated herein and in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. In the place of this incomplete or unavailable information, BOEM’s subject-matter 

experts have used available scientifically credible evidence in this analysis and applied it using accepted

scientific methods and approaches.

4.1.1.7. Topographic Features

BOEM has reexamined the analysis for topographic features presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusions for 

topographic features presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS.

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

CPA proposed action are presented in Chapter 4.2.1.7 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.7 of the WPA 233/CPA 231 Supplemental EIS. A CPA 

proposed action’s incremental contribution to the cumulative impacts is presented below. The following 

information is a summary of the resource description incorporated from Chapter 4.2.1.7 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. Any new information that has 

become available since those documents were published is presented below.

Impacts of Routine and Accidental Events

The potential routine impact-producing factors on topographic features of the CPA are anchoring, 

infrastructure emplacement, drilling effluent and produced-water discharges, and infrastructure removal. 
4-60 Central Planning Area Lease Sales 235, 241, and 247 EIS

These disturbances have the potential to disrupt and alter the environmental, commercial, recreational, 

and aesthetic values of topographic features in the CPA. A detailed impact analysis of the routine impacts 

of OCS activities associated with a CPA proposed action on topographic features can be found in Chapter 

4.2.1.7.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 

4.2.1.7 of the WPA 233/CPA 231 Supplemental EIS.

The topographic features and associated coral reef biota of the CPA could be adversely impacted by 

oil and gas activities resulting from a CPA proposed action in the absence of the proposed Topographic 

Features Stipulation. This would be particularly true should operations occur directly on top of or in the 

immediate vicinity of otherwise protected CPA topographic features.

The No Activity Zone of the topographic features would be most susceptible to adverse impacts if oil 

and gas activities are unrestricted without the proposed Topographic Feature Stipulation. These 

impacting activities could include vessel anchoring and infrastructure emplacement; discharges of 

cuttings and adhered drilling mud, and produced water; and ultimately the explosive removal of 

structures. All the above-listed activities have the potential to considerably alter the diversity, cover, and 

long-term viability of the reef biota found within the No Activity Zone. In most cases, recovery from 

disturbances would take 10 years or more (Fucik et al., 1984; Rogers and Garrison, 2001). Long-lasting 

and possibly irreversible change would be caused mainly by vessel anchoring and structure emplacement 

(pipelines, drill rigs, and platforms). Such activities would physically and mechanically alter benthic 

substrates and their associated biota. Construction discharges would cause substantial and prolonged 

turbidity and sedimentation, possibly impeding the well-being and permanence of the biota and 

interfering with larval settlement, resulting in the decrease of live benthic cover. Finally, the unrestricted 

use of explosives to remove platforms installed in the vicinity of the topographic features could cause 

turbidity and sedimentation that would affect reef biota.

The shunting of cuttings and fluids, which would be required by the proposed Topographic Features

Stipulation, is intended to limit the smothering and crushing of sensitive benthic organisms caused by 

depositing foreign substances onto the topographic features. The impacts from unshunted exploration and 

development discharges of drill cuttings and adhered drilling mud within the exclusion zones would 

impact the biota of topographic features. Specifically, the discharged materials would cause prolonged 

events of turbidity and sedimentation, which could have long-term deleterious effects on local primary 

production, predation, and consumption by benthic and pelagic organisms, biological diversity, and 

benthic live cover. The unrestricted discharge of drill cuttings and adhered fluids during development 

operations would be a further source of impact to the sensitive biological resources of the topographic 

features. Therefore, in the absence of the proposed Topographic Features Stipulation, a CPA proposed 

action could cause significant long-term (10 years or more) adverse impacts to the biota of the 

topographic features (Fucik et al., 1984; Rogers and Garrison, 2001).

The Topographic Features Stipulation, if applied, would prevent most of the potential impacts on 

topographic features from bottom-disturbing activities (structure removal and emplacement) and 

operational discharges associated with a CPA proposed action through avoidance by requiring individual 

activities to be located at specified distances from the feature or zone. Because of the No Activity Zone 

requirement, permit restrictions, and the high-energy environment associated with topographic features, if 

any contaminants reach topographic features, they would be diluted from their original concentration, and 

impacts that do occur would be minimal.

Accidental disturbances resulting from a CPA proposed action, including oil spills and blowouts, 

have the potential to disrupt and alter the environmental, commercial, recreational, and aesthetic values of 

topographic features of the CPA. A detailed impact analysis of the accidental impacts that may be 

associated with proposed CPA Lease Sales 235, 241, and 247 on topographic can be found in Chapter 

4.2.1.7.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 

4.2.1.7 of the WPA 233/CPA 231 Supplemental EIS.

The topographic features and associated coral reef biota of the CPA could be damaged by oil and gas 

activities resulting from a CPA proposed action should they not be restricted by application of the 

proposed Topographic Features Stipulation. The impacting factors that could damage topographic 

features include blowouts, subsea oil spills, and surface oil spills, along with oil-spill response activities 

such as the use of dispersants. 

Oil spills as well as routine activities have the potential to considerably alter the diversity, cover, and 

long-term viability of the reef biota found within the No Activity Zone if the proposed Topographic 

Features Stipulation is not applied. Direct oil contact may result in acute toxicity (Dodge et al., 1984; 
Description of the Environment and Impact Analysis 4-61

Wyers et al., 1986). In most cases, recovery from disturbances would take 10 years or more (Fucik et al., 

1984; Rogers and Garrison, 2001). The use of dispersants near or above protected features could result in 

impacts to the features because dispersants allow floating oil to mix with water. The decision to use 

dispersants near topographic features during an accidental event, however, lies with the Federal On-Scene 

Coordinator and is made on a case-by-case basis.

Disturbances, including oil spills and blowouts, could alter benthic substrates and their associated 

biota over large areas. In the unlikely event of a blowout, sediment resuspension potentially associated 

with oil could cause adverse turbidity and sedimentation conditions. In addition to affecting the live 

cover of a topographic feature, a blowout could alter the local benthic morphology, thus irreversibly 

altering the reef community. Oil spills (surface and subsea) could be harmful to the local biota should the 

oil have a prolonged or recurrent contact with the organisms. Accidental events related to a CPA 

proposed action could cause significant long-term (10 years or more) adverse impacts to the biota of the 

topographic features.

The proposed Topographic Features Stipulation, if applied, would assist in preventing most of the 

potential impacts on topographic feature communities from blowouts, surface, and subsurface oil spills

and the associated effects by increasing the distance of such events from the topographic features. It 

would be expected that the majority of oil released from a blowout would rapidly rise to the surface and 

that the most heavily oiled sediments would likely be deposited on the seafloor before reaching the 

topographic features. Subsea oil would also be directed away from the more sensitive communities on 

the upper levels of topographic features because currents sweep around topographic features instead of 

over them (Rezak et al., 1983; McGrail, 1982). Due to distancing requirements of the Topographic 

Features Stipulation, any turbidity, sedimentation, and oil adsorbed to sediments would also be at low 

concentrations by the time the topographic features were reached, also resulting in sublethal impacts to 

benthic organisms.

In addition, any oil floating in surface waters from a blowout or tanker accidents as a result of OCS 

activity should have minimal impact on topographic features. Due to dilution with the surrounding water 

and the depths of the crests of the topographic features below the water’s surface, surface floating oil 

should not reach topographic features in sufficient concentrations to cause impacts. Floating oil generally 

does not mix below a depth of 10-20 m (33-66 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981a; 

Tkalich and Chan, 2002). The limited depth of mixing should protect most topographic features, very 

few of which rise to within 15 m (50 ft) of the sea surface. As a result, surface oil that may reach the 

benthic communities of topographic features in the Gulf of Mexico would be expected to be at very low 

concentrations (<1 ppm) (McAuliffe et al., 1981a and 1981b; Lewis and Aurand, 1997). Such 

concentrations would not be life threatening to larval or adult stages based on experiments conducted with 

coral (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Knap, 1987; Wyers et al., 1986; Cohen et al., 

1977) and observations after oil spills (Jackson et al., 1989; Guzmán et al., 1991). Any dispersed or 

physically mixed oil in the water column that comes in contact with corals, however, may evoke shortterm negative responses by the organisms, such as reduced feeding and photosynthesis or altered behavior 

(Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 1984). Therefore, impacts from a surface or 

subsea oil spill on topographic features are lessened by the distance of the spill to the features, the depth 

of the features, and the currents that surround the features. In the event that oil from a subsurface spill 

reached an area containing coral cover in lethal concentrations, the recovery could take in excess of 

10 years (Fucik et al., 1984).

Summary and Conclusion

BOEM has reexamined the analysis for topographic features presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for 

topographic features presented in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 

233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 

WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.
4-62 Central Planning Area Lease Sales 235, 241, and 247 EIS

Cumulative Impacts

Background/Introduction 

The proposed Topographic Features Stipulation is assumed to be in effect for this cumulative 

analysis. The continued application of this proposed stipulation would prevent any direct adverse impacts 

on the biota of the topographic features, i.e., impacts potentially generated by oil and gas operations. The 

cumulative impact from routine oil and gas operations includes effects resulting from a CPA proposed 

action, as well as those resulting from past and future OCS oil and gas leasing. These operations include 

anchoring, structure emplacement, muds and cuttings discharge, effluent discharge, blowouts, oil spills, 

and structure removal. Potential non-OCS oil- and gas-related factors include vessel anchoring, treasurehunting activities, import tankering, heavy storms and hurricanes, the collapse of the tops of the 

topographic features due to dissolution of the underlying salt structure, commercial and recreational 

fishing, and recreational scuba diving.

OCS Oil- and Gas-Related Impacts 

Mechanical damage, such as anchoring, is considered to be a catastrophic threat to the biota of 

topographic features. The continued application of the proposed Topographic Features Stipulation 

precludes anchoring on topographic features by OCS oil- and gas-related operations. Detrimental impacts 

would result if oil and gas operators anchored pipeline barges, drilling rigs, and service vessels, or if they 

placed structures on topographic features (Rezak and Bright, 1979; Rezak et al., 1985). The proposed 

Topographic Features Stipulation restricts these activities within 152 m (500 ft) of the No Activity Zone 

around topographic features, thus preventing adverse impacts on benthic communities of topographic 

features (refer to NTL 2009-G39, “Biologically-Sensitive Underwater Features and Areas,” Chapter 

2.3.1.3.1 of this Supplemental EIS, and Chapter 2.3.1.3.1. of the 2012-2017 WPA/CPA Multisale EIS).

The USEPA, through its NPDES discharge permit, enacts mitigating measures on discharges. As 

noted under routine events of a CPA proposed action, drilling fluids can be moderately toxic to marine 

organisms (the more toxic effluents are not allowed to be discharged under NPDES permits), and their 

effects are restricted to areas closest to the discharge point, thus preventing contact with the biota of 

topographic features (Montagna and Harper, 1996; Kennicutt et al., 1996). Small amounts of drilling

effluent in low concentrations may reach a bank from wells outside the No Activity Zone; however, these 

amounts, if measurable, would be extremely small and would be restricted to small areas, with little effect 

on the biota.

The proposed Topographic Features Stipulation protects topographic features by mandating a 

physical distance from drilling activities. Drilling fluid plumes are rapidly dispersed on the OCS; 

approximately 90 percent of the material discharged in drilling a well (cuttings and adhered drilling fluid) 

settles rapidly to the seafloor, while 10 percent forms a plume of fine mud that drifts in the water column 

(Neff, 2005). The shunting of drilling muds and cutting is required for wells drilled in the vicinity of 

topographic features. Shunting restricts the cuttings to a smaller area and places the turbidity plume near 

the seafloor where the environment is frequently turbid and where benthic communities are adapted to 

high levels of turbidity. Water currents moving turbidity plumes across the seafloor would sweep around 

topographic features rather than carrying the turbidity over the banks (Bright and Rezak, 1978). Any 

sediment that may reach coral can be removed by the coral using tentacles and mucus secretion, and it can 

be physically removed by currents that can shed the mucus-trapped particles from the coral (Shinn et al., 

1980; Hudson and Robbin, 1980).

With the inclusion of the proposed Topographic Features Stipulation, no discharges of effluents, 

including produced water, would take place within the No Activity Zone. Drill cuttings in areas around 

the No Activity Zone would be shunted to within 10 m (33 ft) of the seabed. This procedure, combined 

with USEPA’s discharge regulations and permits, should eliminate the threat of discharges reaching and 

affecting the biota of a topographic high. The impacts that these discharges could cause would be 

primarily sublethal damages that could lead to a possible disruption or impairment of a few elements at a 

local scale, but no interference to the general ecosystem performance should occur.

Impacts on the topographic features could occur as a result of OCS oil- and gas-related spills or spills 

from tankering. Due to dilution and the depths of the crests of the topographic features, oil should not 

reach topographic features in sufficient concentrations to cause impacts. Tanker accidents would result in 

surface oil spills, which generally do not mix below a depth of 10-20 m (33-66 ft) (Lange, 1985; 
Description of the Environment and Impact Analysis 4-63

McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002). The limited depth of mixing should protect 

most topographic features, very few of which rise to within 15 m (50 ft) of the sea surface. Any dispersed 

surface oil from a tanker spill that may reach the benthic communities of topographic features in the Gulf 

of Mexico would be expected to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a and

1981b; Lewis and Aurand, 1997). Such concentrations would not be life threatening to larval or adult 

stages based on experiments conducted with coral (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Knap, 

1987; Wyers et al., 1986; Cohen et al., 1977) and observations after oil spills (Jackson et al., 1989; 

Guzmán et al., 1991). Any dispersed or physically mixed oil in the water column that comes in contact 

with corals, however, may evoke short-term negative responses by the organisms, such as reduced 

feeding and photosynthesis or altered behavior (Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 

1984).

Potential blowouts and low-probability catastrophic spills (Appendix B) could impact the biota of the 

topographic features. Based on the proposed Topographic Features Stipulation, few blowouts or lowprobability catastrophic spills, if any, would reach the No Activity Zone around the topographic features. 

The proposed stipulation creates a buffer zone around the banks; this buffer zone would protect the banks 

from direct impacts from damaging amounts of suspended sediment from a seafloor blowout. Most of the 

oil from a seafloor blowout, even a catastrophic one, would rise to the surface, but some of it may be 

entrained in the water column as a subsea plume. Oil in a subsea plume could be carried to a topographic 

feature. The resulting level of impacts depends on the concentration of the oil when it contacts the 

habitat. The farther the blowout is from the topographic feature, the more dispersed the oil and sediment 

will become, reducing the possible impacts. Also, because currents sweep around topographic features 

instead of over them, subsea oil should be directed away from the more sensitive communities on the 

upper levels of topographic features (Rezak et al., 1983; McGrail, 1982). If oil were to contact the 

topographic features, the impacts may include loss of habitat, biodiversity, and live coverage; change in 

community structure; and failed reproductive success. In the highly unlikely event that oil from a 

subsurface spill could reach a coral-covered area in lethal concentrations, the recovery of this area could 

take in excess of 10 years (Fucik et al., 1984).

The cumulative impact of the Deepwater Horizon explosion, oil spill, and response on the 

topographic features of the CPA, if any, is anticipated to be small. The potential oiling footprint as 

reported through NOAA’s Environmental Response Management Application (ERMA) posted on the 

GeoPlatform.gov website indicated that oil was recorded in surface waters of the CPA from 

approximately the western Louisiana border east to Panama City Florida (USDOC, NOAA, 2011d). 

Sackett Bank appeared to be the only bank beneath the oil slick, while only small surface patches of oil 

were reported in water near other banks. These small patches were discontinuous and scattered (USDOC, 

NOAA, 2011d). The crests of the topographic features, however, are deeper than the physical mixing 

ability of surface oil (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002; Rezak 

et al., 1983). Also, most of the oil that migrated west in the CPA, where most of the banks are located, 

was primarily observed close to Louisiana’s Gulf Coast, farther inshore of the banks (USDOC, NOAA, 

2011d). Based on the location of the surface oil, its mixing abilities, the depth of the features, and the 

trajectory of the dispersed subsea plume, most of the topographic features of the CPA should not have 

been impacted by oil from the Deepwater Horizon. 

Water and sediment samples collected during and after the spill were analyzed as part of the OSAT 

(2010) report. A handful of samples collected off the Gulf Coast did reveal some PAH as a result of the 

Deepwater Horizon explosion, oil spill, and response; however, there were no exceedances of USEPA’s 

aquatic life benchmarks measured near topographic features in either water or sediment (OSAT, 2010). 

There were six water samples out of 481 collected that exceeded USEPA’s chronic toxicity benchmarks 

for PAH in the offshore waters (>3 nmi offshore to the 200-m [656-ft] bathymetric contour), all of which 

occurred within 1 m (3 ft) of the water surface (OSAT, 2010). There were 63 water samples out of 3,605 

collected from deep water (>200 m; 656 ft) that exceeded USEPA’s aquatic life benchmarks for PAH 

(OSAT, 2010). Exceedances occurred near the water surface or in the deepwater plume within 70 km 

(44 mi) of the well. Oil detected in the subsurface plume was between 1,100 and 1,300 m (3,609 and 

4,265 ft) and moving southwest along those depth contours (OSAT, 2010), which is deeper than the 

topographic features. No sediment samples collected offshore (>3 nmi offshore to the 200-m [656-ft] 

depth contour) and seven sediment samples collected in deep water (>200 m; 656 ft) exceeded USEPA’s 

aquatic life benchmarks for PAH exposure (OSAT, 2010). All chronic aquatic life benchmark 

exceedances in the sediment occurred within 3 km (2 mi) of the well, and samples fell to background 
4-64 Central Planning Area Lease Sales 235, 241, and 247 EIS

levels at a distance of 10 km (6 mi) from the well (OSAT, 2010). Dispersants were also detected in 

waters off Louisiana, but they were below USEPA’s benchmarks of chronic toxicity. No dispersants 

were detected in sediment on the Gulf floor (OSAT, 2010). Topographic features in the CPA, therefore, 

are not expected to be impacted by PAH in the water column or sediment, as they are located much 

farther from the well than measured benchmark exceedances.

In addition, post oil-spill data (photos, video, water quality collected by semipermeable membrane 

passive sampling devices, sediment, and tissue samples) collected in the CPA (Sonnier Bank) are being 

compared with data that exist from coral reef monitoring programs to quantify the loss of corals, the loss 

of coral community components, and the loss of ecological services provided by the coral communities. 

There has been no documented evidence of Macondo oil, dispersants, or disruption from the response 

activities (USDOC, NOAA, 2012a). Based on the distance of the banks in the CPA from the Macondo

well, the fact that much of the oil was closer inshore than the banks, the crests of the banks are deeper 

than the surface oil mixing capabilities, the measured PAH were below USEPA’s chronic aquatic life 

benchmarks and detection was far from any topographic feature, and the fact that data collected at a bank 

in the CPA did not show evidence of oil or dispersants reaching these features, it is not expected that any 

additional information released as part of the NRDA process following the Deepwater Horizon explosion, 

oil spill, and response would impact BOEM’s analysis of topographic features in the CPA or the potential 

incremental impact on these features. This information, therefore, is not essential to a reasoned choice 

among the alternatives analyzed in this Supplemental EIS.

Platforms will be removed from the OCS Program each year; some may be in the vicinity of 

topographic features (Table 3-2). However, the proposed Topographic Features Stipulation prevents the 

installation of platforms near the No Activity Zone, thus reducing the potential for impact from platform 

removal. The explosive removals of platforms are far enough away to prevent impacts to the biota of the 

topographic features.

Non-OCS Oil- and Gas-Related Impacts

Although the Topographic Features Stipulation prohibits oil and gas leaseholders from anchoring 

vessels and placing structures within 152 m (500 ft) of the No Activity Zone around topographic features, 

the stipulation does not affect other non-OCS oil- and gas-related activities such as fishing, recreational 

scuba diving, or anchoring other vessels on or near these features. Many of the topographic features are 

found near established shipping fairways and are well-known fishing areas. The Flower Garden Banks

National Marine Sanctuary allows conventional hook and line fishing within the boundaries of the 

Sanctuary, which includes Stetson Bank (USDOC, NOAA, 2010a). Also, the Flower Garden Banks and 

several of the shallower topographic features are frequently visited by scuba divers aboard recreational 

vessels (Hickerson et al., 2008). Anchoring at a topographic feature by a vessel involved in any of these 

activities could damage the biota. The degree of damage would depend on the size of the anchor and 

chain (Lissner et al., 1991). Anchor damages incurred by benthic organisms may take more than 10 years 

to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and Garrison, 2001). The 

Flower Garden Banks National Marine Sanctuary prohibits all anchoring within its boundaries and has 

installed numerous mooring buoys at the East and West Flower Garden Banks and Stetson Bank to 

support recreational activities (USDOC, NOAA, 2010a). 

The use of explosives in treasure-hunting operations has become a concern on topographic features. 

Several large holes and serious damage has occurred on Bright Bank, and treasure hunters have damaged 

the bank as recently as 2001; both of these have resulted in the loss of coral cover (Schmahl and 

Hickerson, 2006). The recovery from such destructive activity may take in excess of 10 years and would 

depend on the type and extent of damage incurred by individual features (Fucik et al., 1984; Rogers and 

Garrison, 2001). This activity is not governed by BOEM or NOAA, and it could impact topographic 

features in the Gulf of Mexico.

Impacts from natural occurrences such as hurricanes occasionally result in damage to the biota of the 

topographic features. Hurricane Rita caused severe damage to Sonnier Bank in the CPA (Robbart et al., 

2009). Live cover was reduced at this bank and the disappearance of the sponge colonies, Xestospongia 

muta, was notable (Robbart et al., 2009). The community structure had visibly changed from preHurricane Rita (2004) studies at this bank (Kraus et al., 2006 and 2007). In 2006, the habitat was 

dominated by algae, indicating an alteration in habitat after Hurricane Rita (Kraus et al., 2007). The algal 

cover, however, was the beginning of recovery of the storm-impacted areas, which was further colonized 
Description of the Environment and Impact Analysis 4-65

with sponges (Robbart et al., 2009). Fish community shifts were also observed on Sonnier Bank after 

Hurricane Rita versus before the storm, but clear links have yet to be made to the storm (Kraus et al., 

2007). Hurricane Rita also impacted the Flower Garden Banks in the WPA. Surveys at East Flower 

Garden Bank indicated that coral colonies were toppled, sponges and fields of finger coral (Madracis 

mirabilis) were broken, coral tissues were damaged by suspended sand and rocks, and large-scale shifts 

occurred in sand patches (Hickerson et al., 2008; Hickerson and Schmahl, 2007; Robbart et al., 2009). 

Hurricane Katrina may have caused similar damage on other topographic features in both the CPA and 

WPA. Another possible natural impact to the banks would be the dissolution of the underlying salt 

structure, leading to collapse of the reef (Seni and Jackson, 1983). Dissolution of these salt structures is 

unlikely and beyond regulation abilities.

Depending on the levels of fishing pressure exerted, recreational and commercial fishing activities 

that occur at the topographic features may impact local fish populations. Note that only hook and line 

fishing for both recreational and commercial fishers is permitted within the Flower Garden Banks

National Marine Sanctuary (East Flower Garden Bank, West Flower Garden Bank, and Stetson Bank). In 

addition, 13 reefs in the GOM (Stetson, East Flower Garden, West Flower Garden, 29 Fathom, MacNeil, 

Rankin, McGrail, Geyer, Sonnier, Bouma, Rezak, Alderdice, and Jakkula Banks) have been identified as 

Habitat Areas of Particular Concern (HAPC’s) and measures to prohibit bottom anchoring at the reefs, 

trawling gear, bottom long lines, buoy gear, and fish traps in some HAPC’s have been included in fishery 

management plans of particular HAPC’s (Hickerson et al., 2008). Although certain fishing gears may not 

be prohibited on other banks, mobile gears that disturb the bottom, such as bottom trawls, would probably 

not be used on top of banks because nets can get caught on the features, resulting in snags and tears to the 

gear. The collecting activities by scuba divers on shallow topographic features may also have an adverse 

impact on the local biota. Collecting is prohibited at the Flower Garden Banks National Marine 

Sanctuary (USDOC, NOAA, 2010a). However, anchoring associated with diving and fishing activities 

would be the source of the majority of severe impacts incurred by the topographic features. BOEM does 

not regulate any of these activities, and these activities could impact topographic features in the Gulf of 

Mexico.

Summary and Conclusion

Activities causing mechanical disturbance represent the greatest threat to the topographic features. 

This would, however, be prevented by the continued application of the proposed Topographic Features 

Stipulation. Potential OCS oil- and gas-related impacts include anchoring of vessels and structure 

emplacement, operational discharges (drilling muds and cuttings, and produced waters), blowouts, oil 

spills, and structure removal.

The proposed Topographic Features Stipulation would prevent mechanical damage caused by oil and 

gas leaseholders from impacting the benthic communities of the topographic features and would protect 

them from operational discharges by establishing a buffer around the features. As such, little impact 

would be incurred by the biota of the topographic features. The USEPA’s discharge regulations and 

permits would further reduce discharge-related impacts.

Blowouts and subsea spills could potentially cause damage to benthic biota; however, due to the 

application of the proposed Topographic Features Stipulation distancing OCS activity and sources of 

spills at least 152 m (500 ft) from the No Activity Zone surrounding topographic features, concentrated 

oil would not reach the biota on topographic features, resulting in little impact on the features. The 

majority of oil released below the sea surface would rise and should not physically contact organisms on 

topographic features inside a No Activity Zone. In the unlikely event that oil from a subsurface spill 

would reach the biota of a topographic feature, it would be physically or chemically dispersed to low 

concentrations by the time it reached the feature, and the effects would be primarily sublethal. In 

addition, prevailing currents swept around the banks, which would direct oil in the water column around 

features, not onto them

Surface spills would also have little impact on topographic features. The application of the 

Topographic Features Stipulation would distance oil and gas activity from the topographic features, 

allowing surface oil to mix with surrounding water and diluting it as it travels from the source. Also, 

surface oil would not mix to the depth of the crests of most topographic features, and any oil that could 

mix to the shallower crests would be diluted below concentration known to cause acute impacts to corals. 
4-66 Central Planning Area Lease Sales 235, 241, and 247 EIS

The farther the oil source is from the bank, the more dilute and degraded the oil would be if it reaches the 

vicinity of the topographic features.

In the unlikely event a freighter, tanker, or other oceangoing vessel related to OCS Program activities 

or non-OCS oil- and gas-related activities sank and proceeded to collide with the topographic features or 

associated habitat releasing its cargo and fuel, recovery could take years to decades, depending on the 

extent of the damage. Because these events are rare in occurrence, the potential of impacts from these 

events is considered low.

Non-OCS oil- and gas-related activities could mechanically disrupt the bottom (such as anchoring, 

bottom-disturbing mobile fishing gear, and treasure-hunting activities). Natural events such as hurricanes

or the collapse of the tops of the topographic features (through dissolution of the underlying salt structure) 

could cause severe impacts. The collapsing of topographic features is unlikely and would impact a single 

feature. Impacts from scuba diving, fishing, and discharges or spills from tankering of imported oil not 

related to the OCS Program could have detrimental effects on topographic features, especially because the 

stipulations that BOEM applies to OCS oil and gas activities are not applied to non-OCS oil and gas 

activities and, therefore, cannot require the distancing of all activity from the features.

Overall, the incremental contribution of a CPA proposed action to the cumulative impact is negligible 

when evaluated against all other OCS oil- and gas-related and non-OCS oil- and gas-related impacts in 

the entire GOM. Where the proposed Topographic Features Stipulation is applied, mechanical impacts 

(anchoring and structure emplacement) and impacts from operational discharges (produced waters, 

drilling fluids, cuttings) or accidental discharges (oil spills, blowouts) would be removed from the 

immediate area surrounding the topographic features. However, if the stipulation is not applied, acute 

long-term injury to topographic features may occur as a result of a CPA proposed action.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources (NOAA’s Gulf Spill Restoration Publications website, 

NOAA’s Environmental Response Management Application [ERMA] Gulf Response website, NOAA’s 

Deepwater Horizon Archive Publications and Factsheets, the Gulf of Mexico Sea Grant Deepwater 

Horizon Oil Spill Research and Monitoring Activities Database, the RestoreTheGulf.gov website, and the 

Deepwater Horizon Oil Spill Portal), as well as recently published journal articles and Federal documents 

was conducted to determine the availability of recent information on topographic features. The search 

revealed new information on monitoring of corals in the GOM for impacts of oil from the Deepwater 

Horizon explosion and on the proposed threatened/endangered listing of coral species in the GOM; 

information that is pertinent to this Supplemental EIS.

The NRDA has been investigating the possibility of impacts to shallow-water corals from Texas to 

Florida in the Gulf of Mexico and around to the Atlantic Coast of Florida, following the Florida Reef 

Tract, as a result of the Deepwater Horizon explosion, oil spill, and response. Post oil-spill data (photos, 

video, water quality collected by semipermeable membrane passive sampling devices, sediment, and 

tissue samples) are being compared with data that exist from continuous monitoring at previously 

monitored sites (USDOC, NOAA, 2012a). The goal is to quantify the loss of corals, the loss of coral 

community components, and the loss of ecological services provided by the coral communities. There 

has been no documented evidence of Macondo oil, dispersants, or disruption from the response activities 

within the areas of the CPA that were sampled, specifically Sonnier Bank (USDOC, NOAA, 2012a).

Toxicity tests conducted on larvae in the laboratory on two species of coral, Porites astreoides and 

Montastraea faveolata, indicated that the settlement and survival of coral larvae decreased with 

increasing WAF’s of Macondo oil, the dispersant COREXIT 9500, and WAF’s of Macondo oil plus 

COREXIT 9500 (Goodbody-Gringley et al., 2013). Note that these two species of coral are not found in

banks of the CPA (they are found in the WPA), but that the results are shown as an example in oil 

impacts on coral settlement. The lethal concentration to 50 percent (LC50) of the larval population for the 

WAF’s of Macondo oil was 0.50 ppm and 0.51 ppm for P. astreoides and M. faveolata, respectively. The 

LC50 for COREXIT 9500 for P. astreoides and M. faveolata was 33.4 ppm and 19.7 ppm, while the 

WAF’s of Macondo oil plus COREXIT 9500 LC50 for these species was 1.84 ppm and 0.28 ppm, 

respectively (Goodbody-Gringley et al., 2013). It should be noted, however, that dispersants measured 

during the Deepwater Horizon explosion, oil spill, and response never reached chronic benchmarks in the 

water column (OSAT, 2010). In addition, one must be careful in using WAF’s to determine toxicity in an 
Description of the Environment and Impact Analysis 4-67

open system because it is based on a closed system reaching equilibrium with a contaminant, something 

that will not happen in the GOM. Therefore, the WAF’s of Macondo oil and WAF’s of Macondo oil plus 

COREXIT 9500 may not be applicable for the GOM and could be considered a “worst-case scenario” if 

the entire GOM were to come into equilibrium with oil and dispersant inputs. Therefore, these laboratory 

derived values do not accurately reflect field conditions.

In 2009, a petition was submitted to NMFS by the Center for Biological Diversity to list 83 additional 

species of coral under the ESA (Center for Biological Diversity, 2009). Those 83 “candidate species” 

were reviewed by NMFS. In April 2012, NMFS completed a Status Review Report and a Draft 

Management Report of the candidate species of corals, and on December 7, 2012, the “Proposed Listing 

Determinations for 82 Reef-Building Coral Species; Proposed Reclassification of Acropora palmata and 

Acropora cervicornis from Threatened to Endangered” was published in the Federal Register (Federal 

Register, 2012b). The NOAA determined that 12 of the petitioned species warranted listing as 

endangered (5 in the Caribbean and 7 in the Indo-pacific), 54 species warranted listing as threatened (2 in 

the Caribbean and 52 in the Indo-Pacific), and 16 did not warrant listing under the ESA. The coral found 

in the CPA (on McGrail Bank) proposed for listing as threatened is Agaricia lamarcki. The public 

comment period was extended to April 6, 2013, and a public meeting was held on March 12, 2013 

(Federal Register, 2013g). A final decision on the listing of these species has not been made at this time. 

If these proposed species are listed, then BOEM would consult with NMFS under Section 7 of the ESA if 

an action may affect the listed species or designated critical habitat, as BOEM currently does for other 

listed species.

Limited data are currently available on potential impacts of the Deepwater Horizon explosion, oil 

spill, and response on the topographic features in the CPA. This incomplete or unavailable information 

may be relevant to reasonably foreseeable significant impacts to topographic features. Relevant data on 

the status of topographic features after the Deepwater Horizon explosion, oil spill, and response may take 

years to acquire and analyze. Much of these data are being developed through the NRDA process, which 

may take years to complete. Little data from the NRDA process have been made available to date. 

Therefore, it is not possible for BOEM to obtain this information within the timeline contemplated in the 

NEPA analysis of this Supplemental EIS, regardless of the cost or resources needed. BOEM has 

determined that this incomplete or unavailable information may be essential to a reasoned choice among 

alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. In the place of this incomplete or unavailable information, BOEM’s 

subject-matter experts have used available scientifically credible evidence in this analysis and applied it 

using accepted scientific methods and approaches.

4.1.1.8. Sargassum Communities

BOEM has reexamined the analysis for Sargassum communities presented in the 2012-2017 

WPA/CPA Multisale EIS, based on the additional information presented below. No new significant 

information was discovered that would alter the impact conclusion for Sargassum communities presented 

in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The analysis and

potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 

231 Supplemental EIS still apply for proposed CPA Lease Sale 235, 241, and 247.

A detailed description of Sargassum communities and full analyses of the potential impacts of routine 

activities and accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.8 

the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.8 of the 

WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the 

cumulative impacts is presented below. The following information is a summary of the resource 

description and impact analyses incorporated from the 2012-2017 WPA/CPA Multisale EIS and the

updated information provided in the WPA 233/CPA 231 Supplemental EIS. Any new information that 

has become available since the documents were published is presented below.

Sargassum is one of the most ecologically important brown algal genera found in the pelagic 

environment of tropical and subtropical regions of the world. The pelagic complex in the GOM is mainly 

comprised of S. natans and S. fluitans (Lee and Moser, 1998; Stoner, 1983; Littler and Littler, 2000). 

Both species of Sargassum live immediately below the water surface and are fully adapted to a pelagic 

existence (Lee and Moser, 1998). These floating plants may be up to a few meters in length and may be 

found floating alone or in larger rafts or mats that support communities of fish and a variety of other 
4-68 Central Planning Area Lease Sales 235, 241, and 247 EIS

marine organisms. The distribution, size, and abundance of Sargassum mats varies depending on 

environmental and physiochemical factors such as temperature, salinity, and dissolved oxygen.

Impacts of Routine and Accidental Events

Impact-producing factors associated with routine events for a CPA proposed action that could affect 

Sargassum may include the following: (1) drilling discharges (muds and cuttings); (2) produced water 

and well treatment chemicals; (3) operational discharges (deck drainage, sanitary and domestic water, 

bilge and ballast water); and (4) physical disturbance from vessel traffic and the presence of exploration 

and production structures (i.e., rigs, platforms, and MODU’s). A detailed impact analysis of the routine 

impacts of OCS activities associated with proposed CPA Lease Sales 235, 241, and 247 on Sargassum

communities can be found in Chapter 4.2.1.8.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated 

information is provided in Chapter 4.2.1.8 of the WPA 233/CPA 231 Supplemental EIS.

Sargassum, is a widely distributed pelagic algae that is ubiquitous in the northwestern Gulf and 

seasonal throughout the central and eastern Gulf and northwest Atlantic. Considering its widespread 

distribution and occurrence in the upper water column near the sea surface, it may be contacted by routine 

discharges from oil and gas operations. All routine discharges, including drilling discharges, produced 

water, and operational discharges (e.g., deck runoff, bilge water, sanitary effluent, etc.) could potentially 

contact Sargassum. However, the quantity and volume of these discharges is relatively small compared 

with the surface area of pelagic waters of the CPA (268,922 km2

; 103,831 mi2). Therefore, although 

discharges would contact Sargassum, potentially transferring contaminants to Sargassum, they would 

only contact a very small portion of the Sargassum population. Because these discharges are highly 

regulated to control toxicity and because they would continue to be diluted in the Gulf water, reducing 

concentrations of any toxic component, produced-water impacts on Sargassum would be minimal.

The impingement by service vessels, working platforms, and drillships would contact only a very 

small portion of the Sargassum population. For those plants coming in contact with OCS equipment, the 

result may be the physical destruction of the plant or the stranding and subsequent desiccation of the 

plant. The impacts to Sargassum that are associated with a CPA proposed action are expected to have 

only minor effects to a small portion of the Sargassum community as a whole and would be resilient to 

the minor effects predicted. Sargassum has a yearly cycle that promotes quick recovery from impacts. 

No measurable impacts are expected to the overall population of the Sargassum community.

Impact-producing factors associated with accidental events for a CPA proposed action that could 

affect Sargassum and its associated communities include (1) spills (i.e., surface oil, fuel spills, and 

underwater well blowouts), (2) spill-response activities, and (3) chemical spills. These impacting factors 

would have varied effects depending on the intensity of the spill and the presence of Sargassum in the 

area of the spill. A detailed impact analysis of the accidental impacts that may be associated with 

proposed CPA Lease Sales 235, 241, and 247 on Sargassum communities can be found in Chapter 

4.2.1.8.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 

4.2.1.8 of the WPA 233/CPA 231 Supplemental EIS.

All types of spills, including surface oil and fuel spills, underwater well blowouts, and chemical 

spills, could potentially contact Sargassum. The quantity and volume of most of these spills would be 

relatively small compared with the surface waters of the CPA (268,922 km2

; 103,831 mi2). Therefore, 

most spills would only contact a very small portion of the Sargassum population. Accidental spills would 

be diluted by the Gulf water and, therefore, concentrations of toxic components that could potentially 

contaminate or kill Sargassum tissues would also be reduced in this scenario. The impacts to Sargassum

that are associated with a CPA proposed action are expected to have only minor effects to a small portion 

of the Sargassum community unless a low-probability catastrophic spill occurs (Appendix B). In the 

case of a very large spill, the Sargassum algae community could result in the death of a large number of 

plants across a geographically large area in the northern Gulf of Mexico. The Sargassum community 

lives in pelagic waters with generally high water quality and is expected to show good resilience to the 

predicted effects of spills. It has a yearly growth cycle that promotes quick recovery from impacts and 

that would be expected to restore typical population levels in 1-2 growing seasons.
Description of the Environment and Impact Analysis 4-69

Summary and Conclusion

BOEM has reexamined the analysis for Sargassum communities presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented above. Although important, no new or significant information was discovered to change the 

conclusions reached that activities associated with the proposed OCS activity will not significantly impact 

Sargassum communities presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

Cumulative Impacts

Background/Introduction 

Cumulative impacts from OCS oil- and gas-related operations include effects resulting from a CPA 

proposed action, as well as those resulting from past and future OCS leasing. These operations include 

drilling discharges, produced water and well treatment chemicals, operational discharges, and physical 

disturbance from OCS oil- and gas-related vessels and structures. Potential non-OCS oil- and gas-related 

factors include hurricanes, water quality, and non-OCS vessel traffic. For additional information on the 

potential cumulative impacts to Sargassum communities, refer to Chapter 4.2.1.8.4 of the 2012-2017 

WPA/CPA Multisale EIS and Chapter 4.2.1.8 of the WPA 233/CPA 231 Supplemental EIS, which are 

hereby incorporated by reference.

OCS Oil- and Gas-Related Impacts 

Pelagic Sargassum floats near the surface in oceanic waters and is moved by surface currents 

throughout the GOM. It can be found from scattered clumps to large mats. Vessel passage and stationary 

structures can have minor physical impacts on Sargassum. Vessels transiting the GOM pass through 

Sargassum mats, producing slight impacts to the Sargassum community by breaking up clumps/mats or 

physically destroying the plant. None of these would have more than minor localized effects to the 

affected mats as these mats routinely break up. Oil and gas structures can alter the movement of 

Sargassum mats and entrap small quantities of the algae. This is expected to be a minor impact with 

minimal consequences to the overall Sargassum community.

The discharge of drill cuttings with small quantities of associated drilling muds from oil and gas 

drilling can result in impacts to the Sargassum community, including contamination of the plant tissue by 

metals and chemicals contained within the discharges. Most cuttings from well drilling are discharged 

from the drill platform at the sea surface. This creates an area of high turbidity in the vicinity of drill 

operations, but the cuttings are typically deposited on the seafloor within 1,000 m (3,280 ft) of the 

discharge location. Some fine components of the plume may travel farther but they are dispersed in low 

concentrations throughout the water column (CSA, 2004; NRC, 1983). Exposure of Sargassum to 

discharges would be minimal as the composition of the discharges are limited by NPDES regulations to 

ensure that toxicity levels are low. These effects would be localized to small portions of Sargassum and 

represent a negligible amount of the incremental impact to Sargassum communities.

Effluents from marine vessels of all types and from oil and gas platforms and drillships can affect 

Sargassum. Runoff water from the decks of ships and platforms may contain small quantities of oil, 

metals, and other contaminants. Larger vessels and offshore platforms discharge effluents from sanitary 

facilities (gray water). They also circulate seawater to cool the ships’ engines, electric generators, and 

other machines. The cooling water discharge may be up to 11o

C (20oF) 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 ships, this would only occur when the vessel is 

stationary. For oil and gas platforms, drillships, and offshore LNG terminals, 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 100 m (328 ft) of the source 

(USDHS, CG, and USDOT, MARAD, 2003). Effects from gray water, deck runoff, and cooling water 

are only notable for stationary locations. Produced waters from stationary locations are rapidly diluted 

and impacts are only observed within 100 m (328 ft) of the discharge point (Neff and Sauer, 1991; Trefry 
4-70 Central Planning Area Lease Sales 235, 241, and 247 EIS

et al., 1995; Gittings et al., 1992b). Effluent discharges are also limited by NPDES regulations. The 

effects are localized, with only brief contact to passing Sargassum before dilution to background levels. 

The effect on plants or animals could be the contamination of tissues by toxins that could result in an 

increase in physiological stress while processing the contaminants. 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 the sinking of algae and organisms contacted. The size of the overall effect on 

Sargassum would depend on the size of the spill and the success of spill-response efforts. A lowprobability catastrophic spill, which is not reasonably expected and not part of a CPA proposed action,

such as the Deepwater Horizon oil spill, could have noticeable impacts to the overall Sargassum

community (Appendix B). These impacts could destroy a sizable portion of Sargassum habitat wherever 

the surface slick of oil travels. The effects could reduce the supply of algae transiting from the GOM to 

the Atlantic. This effect, although large, would contact only a portion of the algae in the region of the 

spill. Sargassum algae are a widespread habitat with patchy distribution across the northern GOM and 

the western Atlantic. Due to the vegetative production of Sargassum algae, the community would likely 

recover within 1-2 seasons (1-2 years). If such a spill does occur, it would account for a sizable portion of 

the cumulative impact that affects Sargassum, although even such an impact would affect only a portion 

of the Sargassum in the region of its occurrence.

Turbulence from wakes and direct damage from propellers on vessels servicing OCS activities could 

affect Sargassum by breaking up mats or destroying strands. However, the amount of damage that 

vessels could inflict on a Sargassum mat would be minimized because of Sargassum’s temporary nature. 

Sargassum mats are naturally loose knit with the ability to break apart and reform. Any vessel-related 

damage would likely be seen in the community of organisms inhabiting these mats, which may be killed 

when being struck by a vessel. Sea turtles and small fishes that reside in (rather than below) Sargassum

mats would be most susceptible to this type of damage. However, the foot print of any vessel in the CPA 

is small compared with the distribution of Sargassum, and its transitory life history minimizes the 

possibility that any mat or the inhabitants are routinely affected. Because the proposed activity is not 

expected to substantially increase (if any) the number of OCS oil- and gas-related vessels, it is likely that 

OCS activities will only have a minimum and local effect on the Sargassum community.

Non-OCS Oil- and Gas-Related Impacts

Hurricanes are major natural sources of impacts that affect the Sargassum. The energy associated 

with these storms can break up mats, destroy strands, and displace animals; however, the life history and 

the widespread distribution of Sargassum communities minimizes the probability that any given storm 

will have any lasting population-level effects. Violent surface turbulence caused by these storms would 

dislocate many of the organisms living on and in the Sargassum. Some of the organisms (those that 

cannot swim or swim only weakly) such as nudibranchs (sea slugs), shrimp, Sargassum fish (Histrio 

histrio), and pipefish (Syngnathus spp.) would become separated from the algae. Without cover, many

would fall prey to fish after a storm; others may sink to the seafloor and die. Some epifauna, such as 

hydroids, living on the algae may suffer physical damage or be broken off. Hurricanes can also drive 

Sargassum into waters less conducive for growth and can strand large quantities on beaches. In addition, 

Sargassum communities may be susceptible to nonpoint source pollution from land-based runoffs 

carrying pollutants and excessive nutrients, especially in nearshore areas. The results could be a 

basinwide reduction in Sargassum biomass. Turbulence from wakes, direct damage from propellers, 

impingement on non-OCS vessels (i.e., commercial shipping, fishing activity, and pleasure boating) could 

also affect Sargassum by breaking up mats, destroying plants, or stranding plants. However, the amount 

of damage that vessels could inflict on a Sargassum mat would be minimized because of Sargassum’s

transitory nature. Sargassum mats are naturally loose knit with the ability to break apart and reform. Any 

vessel-related damage would likely be seen in the community of organisms inhabiting these mats, which 

may be killed by being struck by a vessel. Sea turtles and small fishes that reside in (rather than below) 

Sargassum mats would be most susceptible to this type of damage. Compared with the OCS, the number 

of vessels involved in fishing activities, pleasure boating, and commercial shipping activities far exceeds 

the number of OCS oil- and gas-related vessels.
Description of the Environment and Impact Analysis 4-71

Summary and Conclusion

Because of the temporary nature and widespread distribution of Sargassum communities, the 

cumulative effects of all OCS oil- and gas-related and non-OCS oil- and gas-related impacts associated 

with a CPA proposed action would have a localized and short-term effect. Sargassum occurs seasonally 

in almost every part of the northern GOM, resulting in a wide distribution over a very large area. 

However, its occurrence is patchy, drifting in floating mats that are occasionally impinged on ships and 

on oil and gas structures. This large, scattered, patchy distribution results in only a small portion of the 

total community contacting OCS oil- and gas-related ships, structures, or drilling discharges. Contact 

with drilling discharges and discharges of effluent from ships’ operations also results in only short-term, 

localized effects. Because discharges are highly regulated to limit toxicity and because they would 

continue to be diluted in the GOM waters, concentrations of any toxic components related to a CPA 

proposed action would be limited. In the event that a low-probability catastrophic spill, which is not 

reasonably expected and not part of a CPA proposed action, would occur, Sargassum and its associated 

inhabitants in that area are expected to suffer mortality (Appendix B). However, Sargassum is highly 

resilient and recovery is expected within 1-2 growing seasons. The incremental contribution of a CPA 

proposed action to the overall cumulative impacts on Sargassum communities that would result from the 

OCS Program, when compared with environmental factors (such as hurricanes and coastal water quality), 

and non-OCS oil- and gas-related activities (such as non-OCS oil- and gas-related vessel traffic), is

expected to be minimal.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search was conducted for new information published since the publication of the 2012-2017 

WPA/CPA Multisale EIS. A search of Internet information sources, including scientific journals, 

published information from universities and research institutes, and governmental resource agencies, was 

conducted to determine the availability of new information. One of the primary publications relevant to 

this Supplemental EIS is the identification of the northwest Gulf of Mexico and the area near the mouth of 

the Amazon River as “nursery areas” for Sargassum in the Sargasso Sea. Estimates suggest that between 

0.6 and 6 million tonnes of Sargassum are present annually in the Gulf of Mexico, with an additional 

100 million metric tons exported to the Atlantic basin (Gower and King, 2008, Gower and King 2011, 

Gower et al. 2013). In addition, Rooker et al. (2012) quantified the use of Sargassum by billfishes in the 

Gulf of Mexico and concluded that the Sargassum biomass was not a suitable habitat for most juvenile 

billfishes because it can concentrate predators.

There remains incomplete or unavailable information on the effects of the Deepwater Horizon

explosion, oil spill, and response on Sargassum that may be relevant to reasonably foreseeable significant 

adverse impacts. What scientifically credible information is available has been applied by BOEM’s 

subject-matter experts using accepted scientific methodologies. Samples and results developed as part of 

the NRDA process have not been released and there is no timeline for this information becoming 

available. Nevertheless, BOEM has determined that this incomplete or unavailable information is not 

essential to a reasoned choice among alternatives for the reasons stated herein and in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS because Sargassum is widely 

distributed throughout the Gulf and the yearly cycle of replenishment for Sargassum indicates that 

impacts from the Deepwater Horizon explosion, oil spill, and response would be significantly reduced or 

eliminated within a year or two.

4.1.1.9. Chemosynthetic Deepwater Benthic Communities

BOEM has reexamined the analysis for chemosynthetic deepwater benthic communities presented in 

the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the 

additional information presented below. No new significant information was discovered that would alter 

the impact conclusion for chemosynthetic deepwater benthic communities presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

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

CPA proposed action are presented in Chapter 4.2.1.9 of the 2012-2017 WPA/CPA Multisale EIS, and 
4-72 Central Planning Area Lease Sales 235, 241, and 247 EIS

updated information is provided in Chapter 4.2.1.9 of the WPA 233/CPA 231 Supplemental EIS. A CPA 

proposed action’s incremental contribution to the cumulative impacts is presented below. The following 

information is a summary of the resource description incorporated from the 2012-2017 WPA/CPA 

Multisale EIS and the updated information provided in the WPA 233/CPA 231 Supplemental EIS. Any 

new information that has become available since those documents were published is presented below.

Impacts of Routine and Accidental Events

The potential routine impact-producing factors on chemosynthetic deepwater benthic communities of 

the CPA are bottom-disturbing activities associated with anchoring, structure emplacement, pipelaying, 

structure removal, and discharges of drill cuttings, muds, and produced water. Analysis of the routine 

impacts of OCS activities associated with a CPA proposed action on chemosynthetic deepwater benthic 

communities can be found in Chapter 4.2.1.9.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated

information is provided in Chapter 4.2.1.9 of the WPA 233/CPA 231 Supplemental EIS.

Considerable mechanical damage could be inflicted upon deepwater chemosynthetic communities by 

routine OCS drilling activities associated with a CPA proposed action if mitigations are not applied. 

Bottom-disturbing activities associated with anchoring, structure emplacement, pipelaying, and structure 

removal cause localized bottom disturbances and disruption of benthic communities in the immediate 

area. Routine discharge of drill cuttings with associated muds can also affect the seafloor. Without 

mitigating measures, these activities could result in smothering by the suspension of sediments or the 

crushing of organisms residing in these communities. Because of the avoidance guidance provided in 

NTL 2009-G40, “Deepwater Benthic Communities,” the risk of these physical impacts are greatly 

reduced by requiring the avoidance of potential chemosynthetic communities. Discharges of produced 

waters on the sea surface, chemical spills, and deck runoff would be diluted in surface waters, having no 

effect on seafloor habitats. Impacts from bottom-disturbing activities directly on chemosynthetic 

communities are expected to be extremely rare because of the application of required protective measures 

as guidance provided by NTL 2009-G40. Information included in required hazards surveys for oil and 

gas activities depicts areas that could potentially harbor chemosynthetic communities. This allows 

BOEM to require avoidance of any areas that are conducive to chemosynthetic growth. If a high-density 

community is subjected to direct impacts by bottom-disturbing activities, potentially severe or 

catastrophic impacts could occur due to raking of the sea bottom by anchors and anchor chains, and 

partial or complete burial by muds and cuttings. The severity of such an impact is such that there would 

be incremental losses of productivity, reproduction, community relationships, and overall ecological 

functions of the local community, and incremental damage to ecological relationships with the 

surrounding benthos.

Studies indicate that periods as long as hundreds of years are required to reestablish a seep 

community once it has disappeared (depending on the community type), although it may reappear 

relatively quickly once the process begins, as in the case of a mussel community (Powell, 1995; Fisher, 

1995). Routine activities of a CPA proposed action are expected to cause no damage to the ecological 

function or biological productivity of chemosynthetic communities. Widely scattered, high-density 

chemosynthetic communities would not be expected to experience impacts from routine oil and gas 

activities in deep water because the impacts would be limited by protections, as guidance provided in 

NTL 2009-G40. Impacts on chemosynthetic communities from routine activities associated with a CPA 

proposed action would be minimal to none. A detailed impact analysis of the routine impacts of OCS 

activities associated with proposed CPA Lease Sales 235, 241, and 247 on chemosynthetic communities 

can be found in Chapter 4.2.1.9.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.9 of the WPA 233/CPA 231 Supplemental EIS.

Accidental disturbances from a CPA proposed action, including oil spills and blowouts, have the 

potential to result in impacts on chemosynthetic communities of the CPA. Analysis of the accidental 

impacts that may be associated with proposed CPA Lease Sales 235, 241, and 247 on chemosynthetic 

communities can be found in Chapter 4.2.1.9.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated 

information is provided in Chapter 4.2.1.9 of the WPA 233/CPA 231 Supplemental EIS.

Accidental events that could impact chemosynthetic communities are primarily limited to seafloor 

blowouts. A blowout at the seafloor could create a crater and could resuspend and disperse large 

quantities of bottom sediments within a 300-m (984-ft) radius from the blowout site. This could bury 

organisms located within that distance to some degree. The application of avoidance criteria for 
Description of the Environment and Impact Analysis 4-73

chemosynthetic communities provided as guidance in NTL 2009-G40 precludes the placement of a well 

within 610 m (2,000 ft) of any suspected site of a chemosynthetic community, therefore distancing the 

chemosynthetic community from the sedimentation resulting from a possible blowout.

Chemosynthetic communities could be susceptible to physical impacts, including smothering, from a 

blowout depending on bottom-current conditions. The guidance provided in NTL 2009-G40 greatly 

reduces the risk of these physical impacts by requiring a buffer of 610 m (2,000 ft) from wells. It clarifies 

the requirement to avoid potential chemosynthetic communities identified on the required geophysical 

survey records prior to approval of the structure emplacement. The 610-m (2,000-ft) avoidance required 

would protect sensitive communities from heavy sedimentation, with only light sediment components 

able to reach the communities in small quantities.

Studies indicate that periods as long as hundreds of years are required to reestablish a seep 

community once it has disappeared (depending on the community type) (Powell, 1995; Fisher, 1995). 

There is evidence that substantial impacts on these communities could permanently prevent 

reestablishment, particularly if hard substrate required for recolonization is buried by resuspended 

sediments from a blowout. 

Potential accidental impacts from a CPA proposed action are expected to cause little damage to the 

ecological function or biological productivity of widely scattered, high-density chemosynthetic 

communities located at more than 610 m (2,000 ft) away from a blowout. Chemosynthetic communities 

could experience minor impacts from resuspended sediments that travel with currents, although the 

sediment concentration would be diluted with distance from the well.

If dispersants are applied to an oil spill, or if oil is ejected under high pressure, oil would mix into the 

water column, be carried by underwater currents, and eventually contact the seafloor in some form, either 

concentrated (near the source) or decayed (farther from the source), where it may impact patches of 

chemosynthetic community habitat in its path. As with sediments, the farther the dispersed oil travels, the 

more diluted the oil will become as it mixes with surrounding water.

There is some reason to believe the presence of oil would have a limited effect on chemosynthetic 

organisms because these communities live among oil and gas seeps; however, natural seepage is very 

constant and at very low rates as compared with the potential volume of oil released from a blowout or 

pipeline rupture. In addition, organisms inhabit certain niches within the gradients found at oil seeps, 

choosing locations with enough hydrocarbons to sustain their metabolism but not enough to be toxic. All 

seep organisms also require unrestricted access to oxygenated water at the same time as exposure to 

hydrocarbon energy sources. Oil plumes that contact the seafloor before degrading could potentially 

affect sensitive benthic communities if they happen to encounter such a habitat in a localized area.

Accidental impacts associated with a CPA proposed action would likely result in only minimal 

impacts to chemosynthetic communities with adherence to the proposed biological stipulation and the 

guidance provided in NTL 2009-G40. One exception would be in the case of a low-probability 

catastrophic spill (Appendix B) combined with the application of dispersant or high-pressure ejection of 

oil, producing the potential to cause devastating effects on local patches of habitat in the path of subsea 

plumes where they physically contact the seafloor. The possible impacts, however, will be localized due 

to the directional movement of oil plumes by the water currents and because the sensitive habitats have a 

scattered, patchy distribution. Oil plumes that remain in the water column for longer periods would 

disperse and decay, having only minimal effect.

Summary and Conclusion

BOEM has reexamined the analysis for chemosynthetic communities presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, with the understanding that no 

significant new information on chemosynthetic communities has been published since the release of the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. Therefore, no new 

significant information was discovered that would alter the impact conclusion for chemosynthetic 

communities presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and the 

updated information provided in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA 

Lease Sales 235, 241, and 247.
4-74 Central Planning Area Lease Sales 235, 241, and 247 EIS

Cumulative Impacts

Background/Information 

The greatest potential for cumulative adverse impacts to chemosynthetic deepwater benthic 

communities comes from OCS oil- and gas-related, bottom-disturbing activities associated with pipeline 

and platform emplacement (including templates and subsea completions), associated anchoring activities, 

discharges of muds and cuttings, and seafloor blowout accidents. Other offshore activities (non-OCS oiland gas-related) such as anchoring, fishing and trawling and events such as storms, shipwrecks, and 

climate change can also potentially affect deepwater benthic communities. Impacts attributed to OCS 

activity occur at the same time as impacts due to other governmental and private projects and activities, as 

well as impacts due to pertinent natural processes and events that may adversely affect chemosynthetic 

communities. This cumulative analysis considers the effects of impact-producing factors related to past 

lease sales, a proposed CPA lease sale, reasonably foreseeable lease sale programs, and other natural and 

human impacting factors.

OCS Oil- and Gas-Related Impacts 

The greatest potential for cumulative adverse impacts to occur to the deepwater benthic communities 

would come from those OCS oil- and gas-related, bottom-disturbing activities associated with pipeline 

and platform emplacement (including templates and subsea completions), associated anchoring activities, 

discharges of muds and cuttings, and seafloor blowout accidents including low-probability catastrophic 

spills (Appendix B). 

Sensitive deepwater communities appear to be widely scattered and not as rare as previously 

expected. Recent BOEM analyses of seafloor remote-sensing data indicate over 28,000 locations in the 

deep GOM that represent potential hard bottom habitats (Shedd, 2013). Guidance provided in NTL 

2009-G40 describes surveys and avoidance measures, required prior to drilling or pipeline installation, 

that greatly reduce risks to these habitats. Studies have refined predictive information and confirmed the 

effectiveness of these provisions throughout all depth ranges of the GOM (Brooks et al., 2009). With the 

success of this work, confidence is increasing regarding the use of geophysical signatures for the 

prediction of chemosynthetic communities. These geophysical signatures enable BOEM to locate 

possible chemosynthetic communities and to implement avoidance measures in plan and pipeline reviews, 

which substantially reduce the possibility of impacting a chemosynthetic community.

As exploration and development continue on the Federal OCS, activities have moved farther into the 

deeper water areas of the Gulf of Mexico. These activities will be accompanied by limited unavoidable 

impacts to the soft bottom deepwater benthos from bottom disturbances and disruption of the seafloor 

from associated activities. The extent of these disturbances will be determined by the intensity of 

development in these deepwater regions, and the types of structures and mooring systems used. All 

activity levels for the cumulative scenario in the GOM for the years 2012-2051 are shown in Table 3-3. 

For the GOM deepwater offshore Subareas W200-800, W800-1600, W1600-2400, and W>2400, there are 

currently an estimated 3,180-4,510 exploration and delineation wells, 3,910-5,590 development and 

production wells to be drilled, and 115-141 production structures to be installed through the 40-year 

analysis period.

Drilling discharges and resuspended sediments have a potential to cause minor, mostly sublethal 

impacts to patchy, high-density chemosynthetic communities, but substantial accumulations could result 

in more serious impacts. Sublethal impacts may include possible incremental losses of productivity, 

reproduction, community relationships, overall ecological functions of the community, and incremental 

damage to ecological relationships with the surrounding benthos. Recovery from minor impacts is 

expected within several years, but even minor impacts are not expected based on avoidance measures 

provided by guidance in NTL 2009-G40, which precludes well development within 610 m (2,000 ft) of 

any suspected site of a deepwater benthic community. Routine discharges of drilling muds and cuttings 

have been documented to reach the seafloor in water depths >300 m (984 ft). Drill muds typically settle 

within about 100 m (328 ft) of the well site, while the majority of cuttings fall within 500 m (1,640 ft) 

(CSA, 2006). Potential local cumulative impacts could result from accumulations of muds and cuttings 

resulting from consistent hydrographic conditions and drilling of multiple wells from the same location, 

causing concentrations of material in a single direction or “splay.” Such concentrations of muds and 

cuttings could extend beyond the distance required between the discharge and chemosynthetic 
Description of the Environment and Impact Analysis 4-75

communities, causing smothering of organisms. It is not expected that detectable levels of muds and 

cuttings discharges from separate developments or from adjacent lease blocks would act as a cumulative 

impact to deepwater benthic communities. Physical separation of well sites, great water depths, and 

adherence to the guidance provided in NTL 2009-G40 prevent separate activities from having 

overlapping effects.

Small impacts are expected to occur infrequently, but the impacts from bottom-disturbing activities, if 

they occur, could be quite severe to the immediate area affected. If such impacts occurred, the 

disturbance could lead to the destruction of a high-density chemosynthetic community from which 

recovery would occur only over long intervals (200+ years for a mature tube-worm colony and 

25-50 years for a mature mussel community) or it would not occur at all (Powell, 1995; Fisher, 1995).

The majority of deepwater chemosynthetic communities is of low density and is widespread 

throughout the deepwater areas of the Gulf. Low-density communities may occasionally sustain minor 

impacts from discharges of drill muds and cuttings or resuspended sediments. These impacts are most 

likely to be sublethal in nature and would be limited in areal extent. The frequency of such an impact is 

expected to be low. Physical disturbance to a small area would not result in a major impact to the 

ecosystem. The consequences of these impacts to these widely distributed, low-density communities are 

considered to be minor with no change to ecological relationships with the surrounding benthos.

High-density communities are widely distributed, but they are few in number and limited in size. 

They have a high standing biomass and productivity. High-density chemosynthetic communities would 

be largely protected by NTL 2009-G40, which serves to prevent impacts by requiring avoidance of 

potential chemosynthetic communities identified by association with geophysical characteristics or by 

requiring photodocumentation to establish the absence of chemosynthetic communities prior to approval 

of the structure or anchor placements.

A blowout at the seafloor could resuspend large quantities of bottom sediments and even create a 

large crater, destroying any organisms in the immediate area. Structure removals and other bottomdisturbing activities could resuspend bottom sediments, but not at magnitudes as great as blowout events. 

Subsea structure removals are not expected in water depths >800 m (2,625 ft), in accordance with 30 CFR 

part 250. The distance of separation required by adherence to the guidance provided in NTL 2009-G40 

would protect chemosynthetic communities from sedimentation effects of deepwater blowouts.

The use of dispersants on surface oil is not anticipated to impact chemosynthetic communities. It is 

reported that chemically dispersed surface oil from the Deepwater Horizon oil spill remained in the top 

6 m (20 ft) of the water column, where it mixed with surrounding waters and biodegraded (Lubchenco 

et al., 2010). Data from other studies on dispersant usage on surface plumes indicate that most of the 

dispersed oil remained in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 

2 m (6 ft) (McAuliffe et al., 1981a). Therefore, oil spills on the sea surface are expected to have little to 

no effect on deepwater benthic communities.

However, subsea oil plumes resulting from a seafloor blowout could affect sensitive deepwater

communities. Major impacts to localized benthic habitat are possible in such an event, particularly when 

chemical dispersants are applied to oil releases at depth. A recent report documents damage to a 

deepwater coral community in an area that oil plume models predicted as the direction of travel for subsea 

oil plumes from the Deepwater Horizon oil spill (White et al., 2012). A coral community about 10 m x 

12 m (33 ft x 40 ft) in size was severely damaged, and the study results identify Macondo oil as present 

on the corals (White et al., 2012; USDOI, BOEMRE, 2010). Such blowouts are rare and may not release 

catastrophic quantities of oil. Oil that is released would normally rise rapidly to the sea surface. 

However, if oil is ejected into deep water under high pressure, a plume of micro-droplets of oil can form. 

Treatment of the oil with dispersants at depth would also form a plume of oil that would be carried in 

whatever direction the water currents flow. This directional flow could only affect seafloor habitats that 

are downstream from the source.

Although the oil plume could be carried into direct contact with the seafloor at some distance from 

the source, a more likely scenario would be for the oil to adhere to other particles and precipitate to the 

seafloor, much like rainfall (Kingston et al., 1995; ITOPF, 2002). Oil would also reach the seafloor 

through consumption by plankton with excretion distributed over the seafloor (ITOPF, 2002). 

Dispersants reduce the oil’s ability to adhere to particles in the water column, slowing its rate of 

precipitation to the seafloor (McAuliffe et al., 1981a; Lewis and Aurand, 1997), and oil droplets remain 

neutrally buoyant in the water column, creating a subsurface plume of oil (Lee et al., 2011a and 2011b; 

Adcroft et al., 2010). These mechanisms would result in a wide distribution of small amounts of oil. This 
4-76 Central Planning Area Lease Sales 235, 241, and 247 EIS

oil would be in the process of biodegradation from bacterial action, which would continue on the seafloor, 

resulting in scattered microhabitats with an enriched carbon environment (Hazen et al., 2010). The 

recovery time from an oiling event, if reestablishment is not permanently prevented, would be similar to 

that occurring from physical disturbance. Impacts to chemosynthetic communities from a catastrophic oil 

spill are described in Appendix B. 

With over 28,000 potential locations of hard bottom habitats, it is likely that any subsea oil plume

traveling more than a few miles on the deep seafloor would cross at least one of these potential habitats 

(Shedd, official communication, 2013). However, the plume may not contact chemosynthetic 

communities at that point. If the plume did make contact, it would result in a localized effect that is not 

expected to alter the wider population of the GOM.

In cases where high-density communities are subjected to greatly dispersed discharges or suspended 

sediments, the impacts are most likely to be sublethal in nature and limited in areal extent. The impacts to 

ecological function of high-density communities would be minor; minor impacts to ecological 

relationships with the surrounding benthos would also be likely.

Because of the great water depths, treated sanitary wastes and produced waters are not expected to 

have any adverse cumulative impacts to any deepwater benthic communities. These effluents would 

undergo a great deal of dilution and dispersion before reaching the bottom, if ever.

Oil and chemical spills on the sea surface are not considered to be a potential source of measurable 

impacts on any deepwater communities because of water depth. Oil spills from the surface would tend to 

float. Oil discharges at depth or on the bottom would tend to rise in the water column and similarly not 

impact the benthos unless dispersants are applied at depth. In the case of chemosynthetic communities, 

there is also reason to expect that animals are resistant to at least low concentrations of dissolved 

hydrocarbons in the water, as communities are typically found growing in oil-saturated sediments and in 

the immediate vicinity of active oil and gas seeps.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS activities such as anchoring, fishing, and trawling, and events such as storms, shipwrecks, 

and climate change can also potentially affect deepwater benthic communities. There are essentially only 

three fish (or “shellfish”) species considered important to deepwater commercial bottom fisheries—the 

yellowedge grouper (Epinephelus flavolimbatus), tilefish (Lopholatilus chameleonticeps), and royal red 

shrimp (Hymenopenaeus robustus). Yellowedge grouper habitat extends to about 275 m (902 ft). Bottom 

longlining for tilefish could potentially result in cumulative impact to deepwater communities, as their 

habitat in the GOM extends to 540 m (1,772 ft) (FishBase, 2006). If contact did occur, impacts from 

bottom longlines would be minimal. Damage resulting from bottom trawling would have a much greater 

impact. The royal red shrimp is fished in some areas of the Gulf. Its depth range spans 180-730 m 

(591-2,395 ft), but most are obtained from depths of 250-475 m (820-1,558 ft) in the northeastern part of 

the Gulf of Mexico (GMFMC, 2004). This species is obtained from trawling using traditional but 

modified shrimp trawls. The use of traps for royal red shrimp was prohibited in Amendment 11 of the 

Shrimp Fishery Management Plan (GMFMC, 2006). If trawling occurred in sensitive areas of deepwater 

habitats, extensive damage to those communities could occur, but the areas where royal red shrimp are 

obtained are not known for hard bottom communities, and the shrimp prefer soft bottom composed of 

sand, clay, or mud (CSA, 2002). Unlike other areas in the Atlantic and in Europe, bottom fishing and 

trawling efforts in the deeper water of the GOM are currently minimal, and impacts to deepwater benthic 

communities are negligible.

Other non-OCS oil- and gas-related sources of cumulative impact to deepwater benthic communities 

would be possible, but they are considered unlikely to occur. Storms generally cause little to no impacts 

at the depths (>300 m; 984 ft) that chemosynthetic communities occur. A storm could potentially cause 

some type of accident that could then cause secondary impacts, such as shipwrecks, but such occurrences 

would be rare. Essentially no anchoring from non-OCS oil- and gas-related activities occurs at the deeper 

water depths considered for these resources (>300 m; 984 ft). Some impacts are highly unlikely yet not 

impossible, such as the sinking of a ship or barge resulting in collision with or contaminant release 

directly on top of a sensitive, high-density chemosynthetic community.

One potential significant, large-scale source of impact could be potential efforts of carbon 

sequestration in the deep sea as a technique to reduce atmospheric carbon dioxide. This concept is still 

being considered but could have major ramifications. One side of the issue, even beyond the problems of 
Description of the Environment and Impact Analysis 4-77

sea-level increase and climate change, includes the serious risk to shallow-water benthic organisms 

through pH decreases, particularly those with calcium carbonate shells and skeletons (e.g., corals, serpulid 

worms, bryozoa, calcareous algae, etc.) (Kleypas et al., 1999; Barry et al., 2005; Shirayama and Thornton, 

2005). However, the impacts of even very small excursions of pH and CO2 in the deep sea could also 

have serious, even global, deep-sea ecosystem impacts. Kita and Ohsumi (2004) suggest sequestration of 

anthropogenic CO2 could help reduce atmospheric CO2, but they also summarize the potentially 

substantial biological impact on marine organisms. This issue continues to gain attention with the 

increased emphasis on climate change. Scientists suggested in the August 2006 issue of the Proceedings 

of the National Academy of Sciences that thousands of years of the Nation’s carbon emissions could be 

stored in undersea sediments along the coasts (Zenz House et al., 2006).

Summary and Conclusion

The most serious, impact-producing factor threatening chemosynthetic communities is physical 

disturbance of the seafloor, which could destroy the organisms of these communities. Such disturbance 

would most likely come from those OCS oil- and gas-related activities associated with pipelaying, 

anchoring, structure emplacement, and seafloor blowouts. There is evidence that substantial impacts on 

these communities could permanently prevent reestablishment.

Possible catastrophic oil spills due to seafloor blowouts have the potential to devastate localized 

deepwater benthic habitats. However, these events are rare and would only affect a small portion of the 

sensitive benthic habitat in the GOM. Refer to Appendix B for a more detailed discussion of catastrophic 

blowouts.

Activities unrelated to the OCS Program include fishing and trawling, State oil and gas activities, 

storms and carbon sequestration. Because of the water depths in areas of chemosynthetic communities

(>300 m; 984 ft) and the low density of commercially valuable fishery species, these activities are not 

expected to impact deepwater benthic communities.

The overall and incremental contribution of a CPA proposed action to cumulative impacts is expected 

to be slight and to result from the effects of the possible impacts caused by physical disturbance of the 

seafloor and minor impacts from sediment resuspension or drill cutting discharges. Cumulative impacts 

to deepwater communities in the GOM are considered negligible because of the remoteness of 

communities from most impacts, the scattered and patchy nature of chemosynthetic communities, and the 

application of BOEM’s avoidance criteria as guidance provided in NTL 2009-G40. A CPA proposed 

activity considered under the cumulative scenario is expected to cause negligible damage to the ecological 

function or biological productivity of chemosynthetic communities as a whole.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A broad Internet search for relevant new information and scientific journal articles made available 

since the publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS was conducted using a publicly available search engine. The websites for Federal and State agencies, 

as well as other organizations, were reviewed for newly released information. Sources investigated 

include the NOAA Ocean Exploration website, the Gulf of Mexico Alliance, USEPA, USGS, and coastal 

universities. Ongoing research projects funded by NOAA and the National Science Foundation are 

investigating chemosynthetic communities and impacts from the Deepwater Horizon explosion, oil spill, 

and response. No new analyses that are relevant to deepwater chemosynthetic communities and that 

would impact those analyses or conclusions have been made available since publication of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

As identified in the resource analyses above and in Chapter 4.2.1.9 of the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, there remains incomplete or unavailable 

information on the effects of the Deepwater Horizon explosion, oil spill, and response on chemosynthetic 

communities that may be relevant to reasonably foreseeable significant adverse impacts. BOEM has 

determined that the information is not essential to a reasoned choice among alternatives because 

chemosynthetic communities are found throughout the Gulf and are in patchy distributions, minimizing 

the number that would be likely to be impacted by any single event. Available scientifically credible 

information has been applied by BOEM’s subject-matter experts using accepted scientific methodologies.
4-78 Central Planning Area Lease Sales 235, 241, and 247 EIS

4.1.1.10.Nonchemosynthetic Deepwater Benthic Communities

BOEM has reexamined the analysis for nonchemosynthetic deepwater benthic communities presented 

in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the 

additional information presented below. No new significant information was discovered that would alter 

the impact conclusion for nonchemosynthetic deepwater benthic communities presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

A detailed description of nonchemosynthetic deepwater benthic communities and the full analyses of 

the potential impacts of routine activities and accidental events associated with a CPA proposed action are 

presented in Chapter 4.2.1.10 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.10 of the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s 

incremental contribution to the cumulative impacts is presented below. Any new information that has 

become available since those documents were published is presented below.

Impacts of Routine and Accidental Events

The potential routine impact-producing factors on nonchemosynthetic deepwater benthic 

communities of the CPA are bottom-disturbing activities associated with anchoring, structure 

emplacement, pipelaying, structure removal, and discharges of drill cuttings, muds, and produced water. 

Analysis of the routine impacts of OCS activities associated with a CPA proposed action on 

nonchemosynthetic deepwater benthic communities can be found in Chapter 4.2.1.10.2 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.10 of the WPA 233/CPA 

231 Supplemental EIS.

Considerable mechanical damage could be inflicted upon sensitive nonchemosynthetic deepwater 

benthic communities by routine OCS drilling activities associated with a CPA proposed action if 

mitigations are not applied. Deepwater live bottom communities, primarily structured by the coral 

Lophelia pertusa, are the nonchemosynthetic deepwater benthic communities that would be sensitive to 

impacts from oil and gas activities. Bottom-disturbing activities associated with anchoring, structure 

emplacement, pipelaying, and structure removal cause localized bottom disturbances and disruption of 

benthic communities in the localized areas. If a sensitive community is subjected to direct impacts by 

bottom-disturbing activities, potentially severe or catastrophic impacts could occur due to raking of the 

sea bottom by anchors and anchor chains and partial or complete burial by muds and cuttings. The 

severity of such an impact is such that there would be incremental losses of productivity, reproduction, 

community relationships, and overall ecological functions of the local community, and incremental 

damage to ecological relationships with the surrounding benthos. Should this occur, it could result in 

recovery times in the order of decades or more with the possibility of the community never recovering 

(FAO, 2008; Jones, 1992; Probert et al., 1997). However, impacts from bottom-disturbing activities 

directly on deepwater coral communities are expected to be rare because of the application of required 

protective measures as guidance provided in NTL 2009-G40, “Deepwater Benthic Communities.”

Routine discharge of drill cuttings with associated muds can also affect the seafloor. In deep water, 

as opposed to shallower areas on the continental shelf, discharges of drilling fluids and cuttings at the sea 

surface are spread across broad areas of the seafloor and are generally distributed in thinner 

accumulations. A deepwater effects study funded by this Agency included determinations of the extent of 

muds and cuttings accumulations in approximately 1,000 m (3,281 ft) of water (CSA, 2006). 

Geophysical and chemical measurements indicated that a layer of cuttings and muds several centimeters 

thick was deposited within a 500-m (1,640-ft) radius of well sites. This suggests that the required 

2,000-ft (610-m) distance would protect deepwater benthic communities from impacts. Discharges of 

produced waters on the sea surface, chemical spills, and deck runoff would be diluted in surface waters, 

having no effect on seafloor habitats.

Routine activities associated with a CPA proposed action are not expected to cause damage to the 

ecological function or biological productivity of sensitive deepwater live bottom communities (deep coral 

reefs) due to the consistent application of BOEM’s protection guidance provided in NTL 2009-G40. 

Information included in required hazards surveys for oil and gas activities depicts areas that could 

potentially harbor nonchemosynthetic communities. This allows BOEM to require avoidance of any 

areas that are conducive to the growth of sensitive hard bottom communities. The same geophysical 

conditions associated with the potential presence of chemosynthetic communities also results in the 
Description of the Environment and Impact Analysis 4-79

potential occurrence of hard carbonate substrate and other associated, deepwater live bottom 

communities. Because of the guidance provided in NTL 2009-G40, these communities are generally 

avoided in exploration and development planning and in bottom-disturbing activities. Impacts on 

sensitive deepwater communities from routine activities associated with a CPA proposed action would be 

minimal to none.

Accidental disturbances resulting from a CPA proposed action, including oil spills and blowouts, 

have the potential to result in impacts to nonchemosynthetic deepwater benthic communities of the CPA. 

An analysis of the accidental impacts that may be associated with proposed CPA Lease Sales 235, 241, 

and 247 on nonchemosynthetic deepwater benthic communities can be found in Chapter 4.2.1.10.3 of the 

2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.10 of the 

WPA 233/CPA 231 Supplemental EIS.

Accidental events that could impact nonchemosynthetic deepwater benthic communities are primarily 

limited to seafloor blowouts. A blowout at the seafloor could create a crater and could resuspend and 

disperse large quantities of bottom sediments within a 300-m (984-ft) radius from the blowout site. This 

would destroy any organisms located within that distance by burial or modification of narrow habitat 

quality requirements. Substantial impacts on these communities could permanently prevent 

reestablishment, particularly if hard substrate required for recolonization is buried by resuspended 

sediments from a blowout. Physical disturbance or destruction of a limited area of benthos or to a limited 

number of megafauna organisms (e.g., brittle stars, sea pens, and crabs) would not result in a major 

impact to the deepwater benthos ecosystem as a whole or even in relation to a small area of the seabed 

within a lease block. The application of avoidance criteria for deepwater coral communities as guidance 

provided in NTL 2009-G40 precludes the placement of a well within 610 m (2,000 ft) of any suspected 

site of a deepwater coral community, therefore distancing the community from sedimentation resulting 

from a possible blowout.

Accidental impacts due to oil spills caused by blowouts associated with a CPA proposed action would 

likely result in only minimal impacts to nonchemosynthetic communities with adherence to the guidance 

provided in NTL 2009-G40. A blowout could result in a catastrophic oil spill, though not reasonably 

foreseeable and not part of a CPA proposed action (Appendix B), but the distance requirements would 

tend to lessen but not necessarily eliminate the impacts. A large subsea spill combined with the 

application of dispersant or high-pressure ejection of oil could mix oil into the water column, resulting in 

a subsea plume. Such a plume could potentially cause devastating effects on local patches of habitat in its 

path where it physically contacts the seafloor. If such an event were to occur, it could take decades to 

reestablish the nonchemosynthetic community in that location. The possible impacts, however, would be 

localized due to the directional movement of an oil plume by the water currents and because the sensitive 

habitats have a scattered, patchy distribution. As with sediments, the farther the dispersed oil travels, the 

more diluted it would become as it mixes with the surrounding water, and bacteria would degrade the oil 

over time (and distance). Oil plumes that remain in the water column for longer periods would disperse 

and decay, having only minimal effect.

Summary and Conclusion

BOEM has reexamined the analysis for nonchemosynthetic deepwater benthic communities presented 

in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the 

additional information presented above. No new significant information was discovered that would alter 

the impact conclusion for nonchemosynthetic communities presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in 

the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Information 

The greatest potential for cumulative adverse impacts to nonchemosynthetic deepwater benthic 

communities comes from OCS oil- and gas-related, bottom-disturbing activities associated with pipeline 

and platform emplacement (including templates and subsea completions), associated anchoring activities, 

discharges of muds and cuttings, and seafloor blowout accidents. Other offshore activities (non-OCS) 
4-80 Central Planning Area Lease Sales 235, 241, and 247 EIS

such as fishing and trawling and events such as climate change can also potentially affect deepwater

benthic communities. Impacts attributed to OCS activity occur at the same time as impacts due to other 

governmental and private projects and activities, as well as impacts due to pertinent natural processes and 

events that may adversely affect nonchemosynthetic communities. The cumulative analysis considers the 

effects of impact-producing factors related to past lease sales, a proposed CPA lease sale, reasonably 

foreseeable lease sale programs, and other natural and human impacting factors.

OCS Oil- and Gas-Related Impacts 

As exploration and development continue on the Federal OCS, activities have moved farther into the 

deeper water areas of the Gulf of Mexico. These activities would threaten sensitive habitats on the 

seafloor in their vicinity through bottom-disturbing activities associated with pipeline and platform 

emplacement (including templates and subsea completions), associated anchoring activities, discharges of 

muds and cuttings, and seafloor blowout accidents. However, these potential impacts are mitigated by the 

application of avoidance requirements as guidance provided in NTL 2009-G40. The extent of these 

disturbances would be determined by the intensity of development in these deepwater regions, the types 

of structures and mooring systems used, and the effective application of the avoidance criteria as guidance 

provided in NTL 2009-G40, which distances oil and gas activity from sensitive deepwater 

nonchemosynthetic communities.

Oil and gas activities on the OCS could affect local areas of deepwater nonchemosynthetic 

communities in several ways. Produced-water discharges and other surface discharges are too dilute by 

the time they would reach the bottom in >300-m (984-ft) water depths to cause impacts to such 

communities. Drilling discharges and resuspended sediments have the potential to cause minor, mostly 

sublethal impacts to patchy, high-density nonchemosynthetic communities, but substantial accumulations 

could result in more serious impacts. Sublethal impacts may include possible incremental losses of 

productivity, reproduction, community relationships, overall ecological functions of the community, and 

incremental damage to ecological relationships with the surrounding benthos. Recovery from minor 

impacts is expected within several years, but even minor impacts are not expected based on avoidance 

measures provided as guidance in NTL 2009-G40, which precludes well development within 610 m 

(2,000 ft) of any suspected site of a deepwater benthic community. If physical disturbance (such as 

anchor damage) or extensive burial by muds and cuttings were to occur to high-density communities, 

impacts could be severe, with recovery time as long as 200 years for mature tube-worm communities 

(Powell, 1995; Fisher, 1995). Routine discharges of drilling muds and cuttings have been documented to 

reach the seafloor in water depths >300 m (984 ft). Drill muds typically settle within about 100 m (328 

ft) of the well site, while the majority of cuttings fall within 500 m (1,640 ft) (CSA, 2006). Potential local 

cumulative impacts could result from accumulations of muds and cuttings resulting from consistent 

hydrographic conditions and the drilling of multiple wells from the same location, causing concentrations 

of material in a single direction or “splay.” Such concentrations of muds and cuttings could potentially 

extend beyond the distance required between the discharge and nonchemosynthetic communities, causing 

smothering of organisms. It is not expected that detectable levels of muds and cuttings discharges from 

separate developments or from adjacent lease blocks would act as a cumulative impact to deepwater 

benthic communities. Physical separation of well sites, great water depths, and adherence to the guidance 

provided in NTL 2009-G40 prevent separate activities from having overlapping effects.

Localized areas of the seafloor may be affected by the installation of deepwater pilings, pipelines, 

anchors, and seafloor templates for mounting equipment. The greatest potential of physical disturbance is 

from anchor chains and cables. Deepwater work typically utilizes fewer anchors than work on the 

continental shelf. Because of the water depth (>300 m; 984 ft), pipelaying vessels and most drillships use 

dynamic positioning instead of anchors. This system uses computerized positioning controls of thrusters 

to maintain the position of the vessel. Most platform structures use numerous large anchors and cables 

that are fixed in place for the duration of the service life of the structure. Structure-removal activities 

could resuspend bottom sediments or cause physical impacts. The potential effects of resuspended 

bottom sediments are similar to those from the discharge of muds and cuttings discussed below. In deep 

water, the probability that infrastructure will be left on the seabed is likely higher. These potential 

impacts are mitigated by the application of avoidance requirements as guidance provided in NTL 2009-

G40.
Description of the Environment and Impact Analysis 4-81

A blowout at the seafloor could resuspend large quantities of bottom sediments and even create a 

large crater, destroying any organisms in the immediate area. Subsea oil plumes resulting from a seafloor 

blowout could affect sensitive deepwater communities. This is especially true if dispersants are applied at 

depth. A recent report documents damage to a deepwater coral community in an area that oil plume 

models predicted as the direction of travel for subsea oil plumes from the Deepwater Horizon oil spill. A 

coral community about 10 m x 12 m (33 ft x 40 ft) in size was severely damaged, and the study results 

identify Macondo oil as present on the corals (White et al., 2012; USDOI, BOEMRE, 2010). Such 

blowouts are rare and may not release catastrophic quantities of oil. An analysis of impacts from a 

catastrophic oil spill is found in Appendix B. Oil that is released would normally rise rapidly to the sea 

surface. However, if oil is ejected into deep water under high pressure, a plume of micro-droplets of oil 

can form. Treatment of the oil with dispersants at depth would also form a plume of oil that would be 

carried in whatever direction the water currents flow. This directional flow could only affect seafloor 

habitats that are downstream from the source. Although the oil plume could be carried into direct contact 

with the seafloor at some distance from the source, a more likely scenario would be for the oil to adhere 

to other particles and precipitate to the seafloor, much like rainfall (Kingston et al., 1995; ITOPF, 2002). 

Oil would also reach the seafloor through consumption by plankton, with excretion distributed over the 

seafloor (ITOPF, 2002). Dispersants reduce the oil’s ability to adhere to particles in the water column, 

slowing its rate of precipitation to the seafloor (McAuliffe et al., 1981a; Lewis and Aurand, 1997), and 

dispersed oil droplets remain neutrally buoyant in the water column, creating a subsurface plume of oil 

(Lee et al., 2011a and 2011b; Adcroft et al., 2010). These mechanisms would result in a wide distribution 

of small amounts of oil. This oil would be in the process of biodegradation from bacterial action, which 

would continue on the seafloor, resulting in scattered microhabitats with an enriched carbon environment 

(Hazen et al., 2010). This suggests that nonchemosynthetic communities could come in contact with 

small amounts of oil in various stages of biodegradation.

Sensitive deepwater communities appear to be widely scattered and not as rare as previously 

expected. Recent BOEM analyses of seafloor remote-sensing data indicate over 28,000 locations in the 

deep GOM that represent potential hard bottom habitats (Shedd, 2013). While it is likely that any subsea 

oil plume traveling more than a few miles on the deep seafloor would approach at least one of these 

potential habitats, the plume may not contact nonchemosynthetic communities at that point. If the plume 

did make contact, it would result in a localized effect that is not expected to alter the wider populations in 

the Gulf of Mexico. Due to the patchy nature of sensitive deepwater communities and the directional 

flow of subsea oil plumes, only localized patches of sensitive communities could be affected.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS activities such as anchoring, fishing, and trawling, and events such as shipwrecks and 

climate change can also potentially affect deepwater benthic communities. There are essentially only 

three fish (or “shellfish”) species considered important to deepwater commercial bottom fisheries—the 

yellowedge grouper (Epinephelus flavolimbatus), tilefish (Lopholatilus chameleonticeps), and royal red 

shrimp (Hymenopenaeus robustus). Yellowedge grouper habitat extends to about 275 m (902 ft). Bottom 

longlining for tilefish could potentially result in cumulative impacts to deepwater communities, as their 

habitat in the GOM extends to 540 m (1,772 ft) (FishBase, 2006). If contact did occur, impacts from 

bottom longlines would be minimal. Damage resulting from bottom trawling would have a much greater 

impact. The royal red shrimp is fished in depths of 250-475 m (820-1,558 ft) in the northeastern part of 

the Gulf of Mexico (GMFMC, 2004). This species is obtained from trawling using traditional but 

modified shrimp trawls. The use of traps for royal red shrimp was prohibited in Amendment 11 of the 

Shrimp Fishery Management Plan (GMFMC, 2006). If trawling occurred in sensitive areas of deepwater 

habitats, extensive damage to those communities could occur, but the areas where royal red shrimp are 

obtained are not known for hard bottom communities, and the shrimp prefer soft bottom composed of 

sand, clay, or mud (CSA, 2002). Unlike other areas in the Atlantic and in Europe, bottom fishing and 

trawling efforts in the deeper water of the CPA are currently minimal, and impacts to deepwater benthic 

communities are negligible.

Other non-OCS oil- and gas-related sources of cumulative impact to deepwater benthic communities 

would be possible, but they are considered unlikely to occur. Essentially no anchoring from non-OCS

oil- and gas-related activities occurs at the deeper water depths considered for these resources (>300 m; 

984 ft). Some impacts are highly unlikely yet not impossible, such as the sinking of a ship or barge, 
4-82 Central Planning Area Lease Sales 235, 241, and 247 EIS

resulting in collision or contaminant release directly on top of a sensitive, high-density 

nonchemosynthetic community.

One potential significant large-scale source of impact could be potential efforts of carbon 

sequestration in the deep sea as a technique to reduce atmospheric carbon dioxide. This concept is still 

being considered but could have major ramifications. One side of the issue, even beyond the problems of 

sea-level increase and climate change, includes the serious risk to shallow-water benthic organisms 

(particularly those with calcium carbonate shells and skeletons, e.g., corals, serpulid worms, bryozoa, 

calcareous algae, etc.) due to pH decreases (Kleypas et al., 1999; Barry et al., 2005; Shirayama and 

Thornton, 2005). However, the impacts of even very small excursions of pH and CO2 in the deep sea 

could also have serious, even global, deep-sea ecosystem impacts. Acidification in the deep waters of the 

oceans could impact deepwater corals by reducing respiration rates (Hennige et al., 2013). Kita and 

Ohsumi (2004) suggest that sequestration of anthropogenic CO2 could help reduce atmospheric CO2, but 

they also summarize the potentially substantial biological impact on marine organisms. The issue 

continues to gain attention with the increased emphasis on climate change. Scientists suggested in the

August 2006 issue of the Proceedings of the National Academy of Sciences that thousands of years of the 

Nation’s carbon emissions could be stored in undersea sediments along the coasts (Zenz House et al., 

2006). Such a plan needs further thought since nutrients in urban runoff to tropical seas are considered to 

be a major contributor to the decline of coral reefs. Substantial additional research is needed before any 

large-scale carbon sequestration actions would take place.

Summary and Conclusion

The most serious, impact-producing factor threatening nonchemosynthetic communities is physical 

disturbance of the seafloor, which could destroy the organisms of these communities. Such disturbance 

would most likely come from those OCS oil- and gas-related activities associated with pipelaying, 

anchoring, structure emplacement, and seafloor blowouts. There is evidence that substantial impacts on 

these communities could permanently prevent reestablishment.

Recent analyses reveal over 28,000 possible hard bottom locations across the deepwater Gulf of 

Mexico. Guidance provided in NTL 2009-G40 describes surveys and avoidance measures required prior 

to drilling or pipeline installation and greatly reduces risks. Studies have refined predictive information 

and have confirmed the effectiveness of these provisions throughout all depth ranges of the GOM (Brooks 

et al., 2009, Shedd, et al., 2011). With the success of this work, confidence is increasing regarding the 

use of geophysical signatures for the prediction of nonchemosynthetic communities. These geophysical 

signatures enable BOEM to locate possible nonchemosynthetic communities and to implement avoidance 

measures in plan and pipeline reviews, which substantially reduces the possibility of impacting a 

nonchemosynthetic community.

Possible catastrophic oil spills due to seafloor blowouts have the potential to devastate localized 

deepwater benthic habitats. Major impacts to localized benthic habitat are possible in such an event, 

particularly when chemical dispersants are applied to oil releases at depth. However, these events are rare 

and would only affect a small portion of the sensitive benthic habitat in the Gulf of Mexico. The recovery 

time from an oiling event, if reestablishment is not permanently prevented, would be similar to that 

occurring from physical disturbance. Refer to Appendix B for a more detailed discussion of catastrophic 

blowouts.

Among the activities unrelated to the OCS Program, fishing and trawling represent the greatest threat 

to nonchemosynthetic communities. Because of the water depths in areas of nonchemosynthetic 

communities (>300 m; 984 ft) and the low density of commercially valuable fishery species, these 

activities are not expected to impact deepwater benthic communities. Storms are unlikely to impact 

communities at such great water depths, but they could cause secondary impacts such as shipwrecks. 

Climate change would potentially impact such communities, primarily if carbon dioxide concentrations 

increased to projected levels, leading to ocean acidification and resulting in impacts to deepwater corals. 

Large-scale carbon sequestration programs, should they ever be initiated, could potentially affect levels of 

pH and CO2 in the deep sea, with potentially substantial biological impacts on marine organisms.

The overall and incremental contribution of a CPA proposed action to cumulative impacts is expected 

to be slight and to result from the effects of the possible impacts caused by physical disturbance of the 

seafloor and minor impacts from sediment resuspension or drill cutting discharges. Cumulative impacts 

to deepwater communities in the GOM are considered negligible because of the remoteness of 
Description of the Environment and Impact Analysis 4-83

communities from most impacts, the scattered and patchy nature of nonchemosynthetic communities, and 

the application of BOEM’s avoidance criteria as guidance provided in NTL 2009-G40. A CPA proposed 

activity considered under the cumulative scenario is expected to cause negligible damage to the ecological 

function or biological productivity of nonchemosynthetic communities as a whole.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A broad Internet search for relevant new information and scientific journal articles made available 

since publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS

was conducted using a publicly available search engine. The websites for Federal and State agencies, as 

well as other organizations, were reviewed for newly released information. Sources investigated include 

the NOAA Ocean Exploration website, the Gulf of Mexico Alliance, USEPA, USGS, Science Direct, 

Elsevier, the NOAA Central Library National Oceanographic Data Center, JSTOR, and coastal 

universities. Ongoing research projects funded by NOAA and the National Science Foundation are 

investigating nonchemosynthetic communities and impacts from the Deepwater Horizon explosion, oil 

spill, and response.

Several studies have been published that provide insight into aspects of the spill and its effects. 

White et al. (2012) provided evidence that the Deepwater Horizon oil spill impacted deepwater 

ecosystems including corals. One deepwater coral site at a depth of 1,370 m (4,495 ft) was reported as 

severely damaged following the Deepwater Horizon explosion and oil spill. The site is in Mississippi 

Canyon Block 294, 11 km (7 mi) southwest of the spill location. The site includes hard substrate 

supporting coral in an area approximately 10 x 12 m (33 x 39 ft) (White et al., 2012). Sabourin et al. 

(2012) found that corals are bioaccumulating PAH’s. Goodbody-Gringley et al. (2013) found that 

experimental exposure of coral larvae to oil and COREXIT significantly decreased larval settlement and 

survival in Montastraea faveolata and Porites astreoides. While the recent research has provided new 

information regarding impacts to nonchemosynthetic communities from oil spills, this new information 

does not change the conclusions of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS because such a low-probability catastrophic event is unlikely to occur and because 

BOEM considered the potential irreversible effects to nonchemosynthetic communities in Appendix B of 

this Supplemental EIS.

As identified in the resource analyses above and in Chapter 4.2.1.10 of the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 2321 Supplemental EIS, there remains incomplete or unavailable 

information on the effects of the Deepwater Horizon explosion, oil spill, and response on deepwater live 

bottom communities that may be relevant to reasonably foreseeable significant adverse impacts. BOEM 

has determined that the information is not essential to a reasoned choice among alternatives because 

deepwater live bottom communities are found throughout the Gulf and are in patchy distributions, 

minimizing the number that would be likely to be impacted by any single event. Available scientifically 

credible information has been applied by BOEM’s subject-matter experts using accepted scientific 

methodologies.

4.1.1.11.Soft Bottom Benthic Communities

BOEM has reexamined the analysis for soft bottom benthic communities presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented below. No new significant information was discovered that would alter the impact conclusion 

for soft bottom benthic communities presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS.

A detailed description of soft bottom benthic communities and the full analyses of the potential 

impacts of routine activities and accidental events associated with a CPA proposed action are presented in 

Chapter 4.2.1.11 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.11 of the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental 

contribution to the cumulative impacts is presented below. Any new information that has become 

available since those documents were published is presented below.
4-84 Central Planning Area Lease Sales 235, 241, and 247 EIS

Impacts of Routine and Accidental Events

A majority of the oil and gas exploration in the GOM is conducted on soft seafloor sediments. The 

potential routine impact-producing factors on soft bottom benthic communities of the CPA are 

infrastructure emplacement (i.e., anchors, structures, and pipelines), turbidity and smothering, drillingeffluent and produced-water discharges, and infrastructure removal. Disturbances of soft bottom benthic 

communities may cause localized disruptions to benthic community composition and an alteration in food 

sources for some large invertebrate and finfish species. A detailed impact analysis of the routine impacts 

of OCS activities associated with a CPA proposed action on soft bottom benthic communities can be 

found in Chapter 4.2.1.11.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.11 of the WPA 233/CPA 231 Supplemental EIS.

Structure placement and anchor damage from support boats and ships, floating drilling units, and 

pipeline-laying vessels are routine oil and gas OCS oil- and gas-related threats that disturb areas of the 

seafloor. The size of the areas affected by chains associated with anchors and pipeline-laying barges 

depends on the water depth, chain length, sizes of anchor and chain, method of placement, wind, and 

current (Lissner et al., 1991). Anchor damage could result in the crushing and smothering of infauna. 

Anchoring often destroys a wide swath of habitat when an anchor is dragged over the seafloor while 

being set or by the vessel swinging at anchor, causing the anchor chain to drag over the seafloor (Lissner 

et al., 1991). Damage to infauna as a result of anchoring may take approximately 1 year to recover, 

depending on the reproductive cycle and immigration of surrounding communities (Rhodes and Germano, 

1982).

Localized impacts to comparatively small areas of the soft bottom benthic communities would occur 

as a result of structure emplacement on the OCS, and the impacts would be on a relatively small area of 

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

; 103,831 mi2) and 

the entire GOM (645,825 km2

; 249,354 mi2). The estimated footprint of all active platforms on the 

continental shelf in the GOM is approximately 14,491,864 ft2 (1.346 km2

; 0.520 mi2) (USDOI, BOEM, 

2014; LGL Ecological Research Associates, Inc. and Science Applications International Corporation, 

1998), which is approximately 0.0002 percent of the estimated area of seafloor in the GOM. Based on 

these values, the impacts that may occur to the seafloor around platforms would be a fraction of the entire 

soft bottom community of the GOM. The placement of a structure on the seafloor would destroy some 

soft bottom benthic habitat; however, the impacts are localized. The greatest impact is the alteration of 

benthic communities as a result of smothering, chemical toxicity, and substrate change.

Routine discharges of drilling muds and cuttings by oil and gas operations could affect biological 

communities and organisms through a variety of mechanisms, including the smothering of organisms 

through deposition, sublethal toxic effects (impacts to growth and reproduction), and change in substrate 

grain size. Smothering of infauna by drilling discharges may be one of the greatest impacts to localized 

communities near a well, especially one that has shunted its cuttings to the seafloor to protect nearby 

sensitive, hard bottom features. The heaviest concentrations of well cuttings and drilling fluids, for both 

water-based and synthetic-based drilling muds, have been reported within 100 m (328 ft) of wells and are 

shown to decrease beyond that distance (Kennicutt et al., 1996; CSA, 2004). The impacts to the benthic 

communities from the deposition of cuttings and muds are localized, and impacts generally occur within a 

few hundred meters of platforms, with the greatest impacts close to the platform. Communities that are 

smothered by cuttings would be replaced by more tolerant pioneering species, resulting in a shift in 

species dominance (Montagna and Harper, 1996). These pioneer habitats would be similar to the early 

successional communities that predominate throughout areas of the Gulf of Mexico that are frequently 

disturbed (Gaston et al., 1998; Diaz and Solow, 1999; Rabalais et al., 2002a). Although impacts are 

locally drastic, cumulative impacts over the seafloor of the Gulf of Mexico are anticipated to be very 

small, as such comparatively small areas are affected.

Produced waters from petroleum production operations are not likely to have a great impact on soft 

bottom communities. Produced waters are rapidly diluted and impacts are generally only observed within 

proximity of the discharge point, and acute toxicity that may result from produced waters occurs “within 

the immediate mixing zone around a production platform” (Gittings et al., 1992a; Holdway, 2002). There 

have been no reported impacts to marine organisms or sediment contamination beyond 100 m (328 ft) of 

the produced-water discharge (Neff and Sauer, 1991; Trefry et al., 1995). Therefore, impacts to infauna 

are anticipated to be localized and only affect a small portion of the entire seafloor of the Gulf of Mexico.
Description of the Environment and Impact Analysis 4-85

Traditional pipeline-laying barges (as opposed to dynamically positioned barges) affect more seafloor 

than other anchoring impacts. These barges typically use an array of 8-12 anchors weighing about 

4,500 kg (10,000 lb) each. While the large anchors crush organisms in their footprint, a much larger area 

is affected by anchor cable sweep as the barge is pulled forward to lay the pipeline by reeling-in forward 

cables and reeling-out aft cables. The anchors are reset repeatedly to forward positions to allow the barge 

to “crawl” forward. In this way, the anchor sweep scours parallel paths on each side of the vessel where 

the cables touch the seafloor. The width of the scoured paths varies with water depth (deeper water 

equals longer cables) and may be as much as 1,500 m (5,000 ft) to each side (only a portion of the cable 

adjacent to the anchor touches the seafloor). Another major impact of the process is pipeline burial. In 

waters ≤60 m (200 ft), pipeline burial is required. This involves trenching up to 3.3 m (10.8 ft) deep in 

the seafloor from a water depth of ≤60 m (200 ft) to shore. This is a severe disturbance of the trenched 

area and creates a large turbidity plume. Resuspended sediments can cause obstruction of filter-feeding 

mechanisms of sedentary organisms and gills of fishes. Adverse impacts from resuspended sediments 

would be temporary, primarily sublethal in nature, and the effects would be limited to areas in the vicinity 

of the barge. Impacts may include “changes in respiration rate, abrasion and puncturing of structures, 

reduced feeding, reduced water filtration rates, smothering, delayed or reduced hatching of eggs, reduced 

larval growth or development, abnormal larval development, or reduced response to physical stimulus” 

(Anchor Environmental CA, L.P., 2003).

Explosive structure-removal operations disturb the seafloor and can physically lift nearby benthic 

organisms from their benthic habitat. An explosion may kill benthic organisms in the immediate blast 

zone by violent uplift or heavy deposition of disturbed sediments on top of organisms. Benthic organisms 

outside of the immediate blast zone are not expected to suffer much damage as many sessile benthic 

organisms are reported to resist the concussive force of structure-removal-type blasts (O’Keeffe and 

Young, 1984). O’Keeffe and Young (1984) also noted “. . . no damage to other invertebrates such as sea 

anemones, polychaete worms, isopods, and amphipods.” Impacts to invertebrates outside of the 

immediate blast zone are anticipated to be minimal as they do not have air bladders inside their bodies 

that may burst with explosions, as some fish do (Schroeder and Love, 2004).

Any activity that may affect the soft bottom communities would only impact a small portion of the 

overall area of the seafloor of the Gulf of Mexico. Because the soft bottom substrate is ubiquitous 

throughout the Gulf of Mexico, there are no lease stipulations to avoid these communities. However, 

other routine practices restrict detrimental activities that could cause undue harm to benthic habitats (e.g., 

discharge restrictions, debris regulations, and NPDES permits).

Accidental disturbances resulting from a CPA proposed action, including oil spills and blowouts, 

have the potential to cause damage to infaunal communities of the CPA. A detailed impact analysis of 

the accidental impacts that may be associated with proposed CPA Lease Sales 235, 241, and 247 on soft 

bottom benthic communities can be found in Chapter 4.2.1.11.3 of the 2012-2017 WPA/CPA Multisale 

EIS, and updated information is provided in Chapter 4.2.1.11 of the WPA 233/CPA 231 Supplemental 

EIS.

Only a very small portion of the seafloor of the Gulf of Mexico would experience lethal impacts as a 

result of blowouts, surface, and subsurface oil spills and the associated affects because of the small 

amount of proportional space that OCS activities occupy on the seafloor. The greatest impacts would be 

closest to the spill, and impacts would decrease with distance from the spill. Contact with spilled oil at a 

distance from the spill would likely cause sublethal to immeasurable effects to benthic organisms because 

the distance of activity would prevent contact with concentrated oil. Oil from a subsurface spill that 

eventually reaches benthic communities would be primarily sublethal, and impacts would be at the local 

community level. Any sedimentation and deposition of oil adhered to sediment would also be at low 

concentrations and widely dispersed by the time it reaches the seafloor, also resulting in sublethal 

impacts. Also, any local communities that are lost would be repopulated fairly rapidly (Neff, 2005). 

Although an oil spill may have some detrimental impacts, especially closest to the occurrence of the spill, 

the impacts may be no greater than natural biological fluctuations (Clark, 1982), and impacts would be to 

a relatively small portion of the overall Gulf of Mexico.

Summary and Conclusion

BOEM has reexamined the analysis for soft bottom benthic communities presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 
4-86 Central Planning Area Lease Sales 235, 241, and 247 EIS

presented above. No new significant information was discovered that would alter the impact conclusion 

for soft bottom benthic communities presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 

WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

The vast majority of the Gulf of Mexico seabed is comprised of soft sediments. Because drilling 

activity is concentrated on the soft seabed, the greatest number of impacts occurs on soft bottom, benthic 

environments and to the animals that live in and on the sediment. This cumulative analysis considers the 

effects of impact-producing factors related to soft bottoms of the Gulf of Mexico continental shelf. A 

CPA proposed action plus those activities related to prior and future OCS lease sales are considered; in 

this discussion, these are referred to as “OCS oil- and gas-related” factors. Specific OCS oil- and gasrelated, impact-producing factors considered in the analysis are structure emplacement and removal, 

anchoring, discharges from well drilling, produced waters, pipeline emplacement, oil spills, and blowouts. 

Other impacting factors (non-OCS oil- and gas-related factors) that may occur and adversely affect soft 

bottom benthic communities include commercial fisheries (bottom trawling), anchoring by recreational 

boats and other non-OCS commercial vessels, spillage from non-OCS oil- and gas-related vessels, cable 

laying, sand mining, hypoxia (low oxygen levels ≤2 ppm), and storm events, all which have the potential 

to damage soft bottom benthic communities.

OCS Oil- and Gas-Related Impacts 

There are no BOEM stipulations that require avoidance of soft bottom benthic communities because 

they are so ubiquitous throughout the seafloor of the Gulf of Mexico. Most of the bottom surface area of 

the GOM (645,825 km2

; 249,354 mi2) and specifically the CPA (268,922 km2; 103,831 mi2) are soft mud 

bottoms, and this substrate is where drilling occurs. It is important to note, however, that because the soft 

bottom benthic communities comprise a majority of the seafloor of the Gulf of Mexico, impacts are not 

detrimental to the Gulfwide community of these habitats. Also, because a large portion of the seafloor is 

subject to natural fluctuations and physical disturbances (such as storms and yearly hypoxic events), a 

permanent early successional community occupies much of the seafloor and enables rapid recovery of 

disturbed areas, including those impacted by OCS oil and gas activity.

Structure placement and anchor damage from support boats and ships, floating drilling units, and 

pipeline-laying vessels are routine OCS oil- and gas-related threats that disturb areas of the seafloor. The 

size of the areas affected by chains associated with anchors and pipeline-laying barges depends on the 

water depth, chain length, sizes of anchor and chain, method of placement, wind, and current (Lissner 

et al., 1991). Anchor damage could result in the crushing and smothering of infauna. Anchoring often 

destroys a wide swath of habitat when an anchor is dragged over the seafloor while being set or by the 

vessel swinging at anchor, causing the anchor chain to drag over the seafloor (Lissner et al., 1991). 

Damage to infauna as a result of anchoring may take approximately 1 year to recover, depending on the 

reproductive cycle and immigration of surrounding communities (Rhodes and Germano, 1982).

The placement of a structure on the seafloor also destroys some soft bottom benthic habitat; however, 

the impacts are localized to comparatively small areas of the seafloor compared with the overall area of 

the seafloor of the CPA (268,922 km2

; 103,831 mi2) and the entire GOM (645,825 km2; 249,354 mi2). 

The estimated footprint of all platforms on the continental shelf in the GOM is approximately 

14,491,864 ft2

 (1,346,338 m2; 0.520 mi2; 1.346 km2) (USDOI, BOEM, 2014; LGL Ecological Research 

Associates, Inc. and Science Applications International Corporation, 1998), which is approximately 

0.0002 percent of the estimated area of seafloor in the GOM. Based on these values, the impacts that may 

occur to the seafloor around platforms would be a fraction of the entire soft bottom community of the 

GOM.

Routine discharges of drilling muds and cuttings by oil and gas operations could affect biological 

communities and organisms through a variety of mechanisms, including the smothering of organisms 

through deposition, sublethal toxic effects (impacts to growth and reproduction), and change in substrate 

grain size. Smothering of infauna by drilling discharges may be one of the greatest impacts to localized 
Description of the Environment and Impact Analysis 4-87

communities near a well, especially one that has shunted its cuttings to the seafloor to protect nearby 

sensitive, hard bottom features. The heaviest concentrations of well cuttings and drilling fluids, for both 

water-based and synthetic-based drilling muds, have been reported within 100 m (328 ft) of wells and are 

shown to decrease beyond that distance (Kennicutt et al., 1996; CSA, 2004). The impacts to the benthic 

communities from the deposition of cuttings and muds are localized, and impacts generally occur within a 

few hundred meters of platforms, with the greatest impacts close to the platform. Communities that are 

smothered by cuttings would be replaced by more tolerant pioneering species, resulting in a shift in 

species dominance (Montagna and Harper, 1996). These pioneer habitats would be similar to the early 

successional communities that predominate throughout areas of the Gulf of Mexico that are frequently 

disturbed (Gaston et al., 1998; Diaz and Solow, 1999; Rabalais et al., 2002a). Although impacts are 

locally drastic, cumulative impacts over the seafloor of the Gulf of Mexico are anticipated to be very 

small, as such comparatively small areas are affected.

Produced waters from petroleum operations are not likely to have a great impact on soft bottom

communities. Produced waters are rapidly diluted and impacts are generally only observed within 

proximity of the discharge point, and acute toxicity that may result from produced waters occurs “within 

the immediate mixing zone around a production platform” (Gittings et al., 1992a; Holdway, 2002). There 

have been no reported impacts to marine organisms or sediment contamination beyond 100 m (328 ft) of 

the produced-water discharge (Neff and Sauer, 1991; Trefry et al., 1995). Therefore, impacts to infauna 

are anticipated to be localized and only affect a small portion of the entire seafloor of the Gulf of Mexico.

Traditional pipeline-laying barges (as opposed to dynamically positioned barges) affect more seafloor 

than other anchoring impacts. These barges typically use an array of 8-12 anchors weighing about 

4,500 kg (10,000 lb) each. While the large anchors crush organisms in their footprint, a much larger area 

is affected by anchor cable sweep as the barge is pulled forward to lay the pipeline by reeling-in forward 

cables and reeling-out aft cables. The anchors are reset repeatedly to forward positions to allow the barge 

to “crawl” forward. In this way, the anchor sweep scours parallel paths on each side of the vessel where 

the cables touch the seafloor. The width of the scoured paths varies with water depth (deeper water 

equals longer cables) and may be as much as 1,500 m (5,000 ft) to each side (only a portion of the cable 

adjacent to the anchor touches the seafloor). Another major impact of the process is pipeline burial. In 

waters ≤60 m (200 ft), pipeline burial is required. This involves trenching up to 3.3 m (10.8 ft) deep in 

the seafloor from a water depth of ≤60 m (200 ft) to shore. This is a severe disturbance of the trenched 

area and creates a large turbidity plume. Resuspended sediments can cause obstruction of filter-feeding 

mechanisms of sedentary organisms and gills of fishes. Adverse impacts from resuspended sediments 

would be temporary, primarily sublethal in nature, and the effects would be limited to areas in the vicinity 

of the barge. Impacts may include “changes in respiration rate, abrasion and puncturing of structures, 

reduced feeding, reduced water filtration rates, smothering, delayed or reduced hatching of eggs, reduced 

larval growth or development, abnormal larval development, or reduced response to physical stimulus” 

(Anchor Environmental CA, L.P., 2003).

Both explosive and nonexplosive structure-removal operations disturb the seafloor and can physically 

lift nearby benthic organisms from their benthic habitat. An explosion may kill benthic organisms in the 

immediate blast zone by violent uplift or heavy deposition of disturbed sediments on top of organisms. 

Benthic organisms outside of the immediate blast zone are not expected to suffer much damage as many 

sessile benthic organisms are reported to resist the concussive force of structure-removal-type blasts 

(O’Keeffe and Young, 1984). O’Keeffe and Young (1984) also noted “. . . no damage to other 

invertebrates such as sea anemones, polychaete worms, isopods, and amphipods.” Impacts to 

invertebrates outside of the immediate blast zone are anticipated to be minimal as they do not have air 

bladders inside their bodies that may burst with explosions, as some fish do (Schroeder and Love, 2004).

Accidental impacts from OCS oil- and gas-related activities can also affect benthic communities. 

Surface oil slicks (released offshore from vessels or released subsea and risen to the sea surface) can be 

moved toward shore by winds, but oil mixed into the water column is moved by water currents, which do 

not generally travel toward shore (Pond and Pickard, 1983; Inoue et al., 2008). Surface oil spills and 

physically dispersed oil released from tankers may impact shallow, nearshore benthic communities. 

Disturbance of the sea surface by storms can mix surface oil 10-20 m (33-66 ft) into the water column 

(McAuliffe et al., 1975 and 1981a; Lange, 1985; Tkalich and Chan, 2002). This may result in direct oil 

contact for shallow, nearshore benthic communities. Direct oiling or exposure to water soluble fractions 

of oil may result in lethal impacts to organisms (Byrne, 1989; Suchanek, 1993; Beiras and Saco-Álvarez, 

2006) or impaired embryonic development (Byrne and Calder, 1977; Nicol et al., 1977; Vashchenko, 
4-88 Central Planning Area Lease Sales 235, 241, and 247 EIS

1980). Benthic communities farther offshore, in deeper water, would be protected from direct physical 

contact of surface oil by depth below the sea surface. Any dispersed surface oil from a tanker or rig spill 

that may reach the benthic communities on the seafloor of the Gulf of Mexico at a depth greater than 

10 m (33 ft) would be expected to be at very low concentrations (less than 1 ppm) (McAuliffe et al., 

1981a and 1981b; Lewis and Aurand, 1997). Such concentrations may not be life threatening to adult 

stages, but they may harm larval or embryonic life stages of benthic organisms (Byrne, 1989; Suchanek, 

1993; Fucik et al., 1995; Beiras and Saco-Álvarez, 2006). 

Blowouts may impact the biota of the soft bottom benthic communities. If any blowouts from wells 

occur, the suspended sediments should settle out of the water column fairly quickly, locally smothering 

benthic organisms near the well. Any oil that adhered to the sediment would also smother the benthic 

communities below. The greatest impacts would be closest to the well, where the heaviest deposits of 

sediment would occur. Any oil that becomes entrained in a subsurface plume would be dispersed as it 

travels in the water column (Vandermuelen, 1982; Tkalich and Chan, 2002). Subsea oil plumes near the 

seafloor would pass over smooth soft bottom, continuing the processes of diffusion and biodegradation. 

These plumes would continue to be dispersed over a wide area in low concentrations with sublethal to 

immeasurable effect. If concentrated oil were to contact the soft bottom communities directly, the 

impacts may include lethal effects with loss of habitat and biodiversity, contamination of substrate, 

change in community structure, and failed reproductive success. Damage to infauna as a result of 

subsurface plume exposure may take approximately 1 year to recover, depending on the reproductive 

cycle and immigration of surrounding communities (Rhodes and Germano, 1982).

Oil that was deposited on the seafloor as a result of the Deepwater Horizon oil spill is discussed in 

this section as part of the cumulative impacts that may occur to soft bottom benthic communities. In 

November 2010, it was estimated that 26 percent of the released oil from the Macondo well remained in 

the environment as oil on or just below the water surface as a light sheen or tarballs; oil that was washed 

ashore or collected from the shore; and oil that was in the sediments (Lubchenco et al., 2010). Currently, 

the bulk deposits of oil have been removed from beaches, and the remaining oil that reached shorelines 

has been buried (e.g., through wave action and hurricanes) and is weathering over time (OSAT-2, 2011). 

The greatest concentrations of oil deposited on the seafloor were near the wellhead, and the 

concentrations decreased with distance from the source. Sediment concentrations of hydrocarbons that 

exceeded USEPA aquatic life benchmarks (concentration for potential adverse effects) occurred in only 

seven samples collected within 3 km (2 mi) of the Macondo well, and concentrations reached background 

levels at 10 km (6 mi) from the well, indicating a limited radius of severe impact (OSAT, 2010). Benthic 

abundance was reduced the most within the 3-km (2-mi) circular radius around the wellhead and was 

moderately affected along an elongated northeast-southwest axis that extends 8.5 km (5.3 mi) northeast 

and 17 km (11 mi) southwest of the wellhead (Montagna et al., 2013). The oil that was deposited on the 

floor of the Gulf has also weathered over time and biodegradation of oil in the sediment was greater with 

distance from the wellhead (OSAT, 2010; Liu et al., 2012). The concentrations of total n-alkanes 

(hydrocarbon chains) and total PAH’s (hydrocarbon rings) were approximately three times higher at a 

station 2 km (1.2 mi) from the wellhead than they were at a station 6 km (3.7 mi) from the wellhead 

1 year after the spill (Liu et al., 2012). The sediment was more enriched with the larger compounds (both

n-alkanes and PAH’s), indicating the biological degradation of the smaller compounds and 

biodegradation was more intense at the station farther from the wellhead.

The cumulative impact to soft bottoms of possible future oil spills, along with the Deepwater Horizon

oil spill, is anticipated to be small. The limited data currently available on the impacts of the Deepwater 

Horizon explosion, oil spill, and response make it difficult to define impacts to the soft bottom 

communities in the GOM; although, as described above, the greatest impacts were close to the well and 

decreased with distance. The PAH’s are also breaking down with time, reducing contamination in the 

affected areas. Also, seafloor samples indicated that the only sediment exceedances of USEPA’s chronic 

aquatic life benchmarks occurred within 3 km (2 mi) of the well and samples fell to background levels at 

a distance of 10 km (6 mi) from the well (OSAT, 2010). Therefore, the acute impacts of any large-scale 

blowout to soft bottom benthic communities would likely be limited in scale and influenced by directional 

currents, and any additive impacts of several blowouts should have acute effects in only small areas, with 

possible sublethal impacts occurring over a larger area. Overall, the locally impacted seafloor will be 

very small compared with the overall size of the seafloor of the CPA (268,922 km2

; 103,831 mi2) to the 

GOM (645,825 km2

; 249,354 mi2). It will not impact the overall infaunal population.
Description of the Environment and Impact Analysis 4-89

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related activities have a greater potential to affect the soft bottom communities 

of the region than BOEM-regulated OCS oil- and gas-related activities. Natural events such as storms, 

extreme weather, and fluctuations of environmental conditions may impact soft bottom infaunal 

communities. Soft bottom communities occur from the shoreline into the deep waters of the Gulf of 

Mexico. Storms can physically affect shallow bottom environments, causing an increase in 

sedimentation, burial of organisms by sediment, a rapid change in salinity or dissolved oxygen levels, 

storm surge scouring, remobilization of contaminants in the sediment, and abrasion and clogging of gills 

as a result of turbidity (Engle et al., 2008). Storms have also been shown to uproot benthic organisms 

from the sediment and suspend organisms in the water column (Dobbs and Vozarik, 1983). Large storms 

may devastate infaunal populations; for example, 2 months after Hurricane Katrina, a significant decrease 

in the number of species, species diversity, and species density occurred in coastal waters off Louisiana, 

Mississippi, and Alabama (Engle et al., 2008). Such impacts may have substantial effects on benthic 

communities, although these impacts are generally temporary as recolonization, and immigration from 

nearby benthic communities should occur within a year. As a result of storm events, a permanent early 

successional community occupies much of the seafloor and enables rapid recovery of disturbed areas.

Hypoxic conditions of inconsistent intensities and ranges also occur annually in a band that stretches 

along the Louisiana-Texas continental shelf each summer (Rabalais et al., 2002a). These conditions can 

be caused by a combination of several factors, including warm water temperature, nutrient input, storm 

runoff, drainage, and algal blooms. The dissolved oxygen levels in the Gulf of Mexico’s hypoxic zone 

are <2 ppm. Such low concentrations are lethal to many benthic organisms and may result in the loss of 

some benthic populations. Recolonization of devastated areas by populations from unaffected 

neighboring soft bottom substrate would be expected to occur within a relatively short period of time 

(Thistle, 1981; Dubois et al., 2009).

Recreational boating, fishing, and import tankering may have limited impact on soft bottom

communities. Ships anchoring near major shipping fairways of the GOM or recreational fishing boats 

setting anchor would impact bottom habitats. Anchor placement may crush and eliminate infauna in the 

footprint of the anchor. Anchoring impacts are localized to the anchor footprint and are temporary, as 

nearby organisms can repopulate the affected area rapidly. Oil spilled from any of these vessels could 

also result in similar impacts to oil spilled from OCS oil- and gas-related vessels.

Damage resulting from commercial fishing, especially bottom trawling, may have a severe impact on 

soft bottom benthic communities. Bottom trawling in the Gulf of Mexico primarily targets shrimp from 

nearshore waters to depths of approximately 90 m (295 ft) (NRC, 2002). Some studies have indicated 

that trawled seafloor has reduced species diversity compared with untrawled seafloor (McConnaughey 

et al., 2000), while others do not show a statistical difference between trawled and untrawled seafloor, 

although species dominance may shift (Van Dolah et al., 1991). Trawl trails may scour sediment, killing 

infauna, and epifaunal organisms may be physically removed (Engel and Kvitek, 1998). A review of the 

use of tickle chains on trawls indicated damage to shallow infauna and surface-dwelling benthic species 

(Van Dolah et al., 1991). Trawling also contributes regularly to turbidity, as nets drag the seafloor, 

leaving trails of suspended sediment. Repetitive disturbance by trawling activity may lead to a 

community dominated by opportunistic species (Engel and Kvitek, 1998). Recovery from the passing of 

a trawl net would begin to occur with the following reproduction cycle of surrounding benthic 

communities (Rhodes and Germano, 1982), but populations may be severely impacted by repetitive 

trawling activity (Engel and Kvitek, 1998).

Cable laying may involve trenching in the seafloor to bury the cable to protect it from seafloor 

disturbances, such as trawling. Seafloor trenching creates a large turbidity plume where resuspended 

sediments can cause obstruction of filter-feeding mechanisms of sedentary organisms and gills of fishes. 

Adverse impacts from resuspended sediments would be temporary, primarily sublethal in nature, and the 

effects would be limited to areas in the vicinity of the trenching activity. Impacts may include “changes 

in respiration rate, abrasion and puncturing of structures, reduced feeding, reduced water filtration rates, 

smothering, delayed or reduced hatching of eggs, reduced larval growth or development, abnormal larval 

development, or reduced response to physical stimulus” (Anchor Environmental CA, L.P., 2003). In turn, 

the suspended sediment may cause heavy depositions that could smother benthic communities below.

Sand mining of the seafloor for the use of replenishing beaches after storm damage can also impact 

soft bottom benthic communities. Mining the seafloor alters the seafloor, which would result in the 
4-90 Central Planning Area Lease Sales 235, 241, and 247 EIS

physical removal of infaunal and epifaunal benthic organisms, displacement of benthic fishes that feed on 

the benthic organisms, suspended sediment and turbidity that can clog gills, and sediment deposition that

can smother organisms (Byrnes et al., 2004; Diaz et al., 2004). Benthic infaunal abundance would 

recover from such activity within 1-3 years, but the recovery of species composition would take longer 

(Byrnes et al., 2004). Initial colonization would include the rapidly reproducing pioneering organisms 

that are abundant in the GOM.

As discussed above, severe physical damage may occur to soft bottom sediments and the associated 

benthic communities as a result of non-OCS oil- and gas-related activities. It is assumed infauna 

associated with soft bottom sediments of the GOM are well adapted to natural disturbances such as 

turbidity and storms. However, human disturbance, such as trawling and sand mining or non-OCS oiland gas- related activity oil spills, could cause severe damage to infauna, possibly leading to changes of 

physical integrity, species diversity, or biological productivity. If such non-OCS oil- and gas-related 

human disturbances were to occur, recovery to pre-impact conditions could take approximately a year 

(Neff, 2005; Lu and Wu, 2006), with the overall recovery time depending on the presence of recolonizers 

nearby, the time of year for reproduction of those colonizers, the currents and water circulation patterns, 

the extent of possible oiling, and the ability of the recolonizers to tolerate the sediment conditions 

(Ganning et al., 1984). Recovery of benthic populations in soft subtidal environments, however, has been 

reported to take up to 5-10 years after oiling (Ganning et al., 1984; Gómez Gesteira and Dauvin, 2000). 

However, because some benthic communities in the northern Gulf of Mexico are permanently in early 

community successional stages due to frequent disturbances, full recovery may occur very quickly 

(Gaston et al., 1998; Diaz and Solow, 1999; Rabalais et al., 2002a).

Summary and Conclusion

Impacts from routine activities of OCS oil- and gas-related operations including anchoring, structure 

emplacement and removal, pipeline emplacement, drilling discharges of muds and cuttings, operational 

discharges of produced waters, accidental oil spills, and blowouts associated with OCS activities may 

have locally devastating impacts on infaunal communities, but the cumulative effect on the overall 

seafloor and infaunal communities on the Gulf of Mexico would be very small. Soft bottom benthic 

communities are ubiquitous throughout the GOM and often remain in an early successional stage due to 

natural fluctuation. Therefore, the activities of OCS production of oil and gas would not cause additional 

severe cumulative impacts to soft bottom benthic communities. Long-term OCS oil- and gas- realted 

activities are not expected to adversely impact the entire soft bottom environment because the local 

impacted areas are extremely small compared with the entire seafloor of the Gulf of Mexico and because 

impacted communities are repopulated relatively quickly.

Non-OCS oil- and gas-related activities that may occur on soft bottom benthic substrate include 

recreational boating and fishing, commercial fishing, import tankering, cable laying, sand mining, and 

natural events such as extreme weather conditions, and extreme fluctuations of environmental conditions. 

These activities could cause temporary damage to soft bottom communities. Ships and fishermen 

anchoring on soft bottoms could crush and smother underlying organisms. Cable laying and sand mining 

could suspend sediments and impact benthic organisms through dermal abrasion, clogged gills, and 

burial. During severe storms, such as hurricanes, large waves may stir bottom sediments, which cause 

scouring, remobilization of contaminants in the sediment, abrasion and clogging of gills as a result of 

turbidity, uprooting benthic organisms from the sediment, and an overall result in decreased species 

diversity (Engle et al., 2008; Dobbs and Vozarik, 1983). Yearly hypoxic events may eliminate many 

species from benthic populations over a wide area covering most of the CPA and part of the WPA 

continental shelf (Rabalais et al., 2002a).

The incremental contribution of a CPA proposed action to the cumulative impact is expected to be 

slight, with possible impacts from physical disturbance of the bottom, discharges of drilling muds and 

cuttings, other OCS discharges, structure removals, and oil spills. Negative impacts, however, are small 

compared with the overall size and ubiquitous composition of the soft bottom benthic communities in the 

Gulf of Mexico. Non-OCS oil- and gas-related factors, such as storms, trawling, non-OCS oil- and gasrelated spills, and hypoxia, are likely to impact the soft bottom communities on a more frequent basis. 

Impacts from OCS activities are also somewhat minimized by the fact that these communities are 

ubiquitous throughout the CPA and can recruit quickly from neighboring areas.
Description of the Environment and Impact Analysis 4-91

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources (NOAA’s Gulf Spill Restoration Publications website, 

NOAA’s Environmental Response Management Application [ERMA] Gulf Response website, NOAA’s 

Deepwater Horizon Archive Publications and Factsheets; the Gulf of Mexico Sea Grant Deepwater 

Horizon Oil Spill Research and Monitoring Activities Database; the RestoreTheGulf.gov website, and the 

Deepwater Horizon Oil Spill Portal), as well as recently published journal articles and Federal documents 

was conducted to determine the availability of recent information on topographic features. The search 

revealed new information on the proposed threatened/endangered listing of coral species in the GOM, 

information that is pertinent to this Supplemental EIS.

Additional information has been published since the release of the OSAT 2010 report. Using the 

sediment data collected during the OSAT effort, the footprint of the Deepwater Horizon oil spill was 

mapped in Geographic Information Systems (GIS) (Montagna et al., 2013). In addition, analyses were 

conducted to determine the correlation between impacts to benthic organisms in relation to total PAH, 

barium, distance from the Deepwater Horizon wellhead, and distances to seeps. Benthic communities 

were altered in areas where there were strong positive correlations with organic enrichment, PAH, and 

barium. For example, nematodes (opportunistic worms) were abundant in areas that had increased 

organic enrichment as a result of the spill (Montagna et al., 2013). The impacts to benthic diversity were 

correlated with the deposition of oil around the wellhead and the directional flow of the subsea plume. 

Benthic abundance was reduced the most within a 3-km (1.9-mi) circular radius around the wellhead and 

was moderately affected along an elongated northeast-southwest axis that extends 8.5 km (5.3 mi) 

northeast and 17 km (10.6 mi) southwest of the wellhead (Montagna et al., 2013). There was not a 

correlation between benthic abundance and diversity and distance from seafloor hydrocarbon seeps, 

indicating that the alterations observed were probably a result of the Deepwater Horizon oil spill. Due to 

the cold temperature, low nutrient concentrations, contaminated sediments, and slow metabolic rates of

deep-sea benthic organisms, recovery to pre-spill conditions is anticipated to take decades or longer in the 

affected areas (Montagna et al., 2013).

The biodegradation of oil from the Deepwater Horizon oil spill on the seafloor was greater farther 

from the wellhead (6 km; 3.7 mi) than closer (2 km; 1.2 mi), likely due to the higher concentration of oil 

deposited on the seafloor closer to the wellhead. The concentrations of total n-alkanes (hydrocarbon 

chains) and total PAH’s (hydrocarbon rings) were approximately three times higher at a station 2 km 

(1.2 mi) from the wellhead than they were at a station 6 km (3.7 mi) from the wellhead one year after the 

spill (Liu et al., 2012). The sediment was more enriched with the larger compounds (both n-alkanes and 

PAH’s), indicating the biological degradation of the smaller compounds and biodegradation was more 

intense at the farther station. The more heavily contaminated site may have had a decreased 

biodegradation rate as a result of oxygen depletion caused by a combination of reduced oxygen 

penetration into the sediment by an oil barrier on the sediment surface and the local depletion of dissolved 

oxygen from bacterial consumption of labile hydrocarbons (Liu et al., 2012). The smaller compounds are 

easier for the bacteria to break down, leaving the sediment enriched in the larger compounds; however, 

labile n-alkanes were still present in the sediment 1 year after the spill, indicating that the biodegradation 

of the oil in sediment is occurring slowly, especially at the more heavily contaminated sites closer to the 

well (Liu et al., 2012).

Oysters from two separate studies have not shown impacts from the Deepwater Horizon oil spill. 

Oysters that were transplanted before, during, and after the Deepwater Horizon oil spill, in areas of 

Mobile Bay and the Mississippi and Alabama coast that were potentially exposed to oil, did not show 

evidence of oil-derived C and N in their shells or tissue (Carmichael et al., 2012). This finding indicates 

that the oysters sampled were either not exposed to oil, did not feed on oiled food sources, or consumed 

too little oiled food to detect in their shells and tissue. It is also possible that the oysters rapidly depurated 

any consumed oil or slowed filter feeding due to the stress of oil exposure. Whatever the reason, because 

oysters did not assimilate oil-derived C and N, they did not provide a contaminated food source to higher 

trophic levels (Carmichael et al., 2012). In addition, oysters collected from oil exposed areas of 

Mississippi Sound 6 months after the Macondo well was capped did not show PAH accumulation (Soniat 

et al., 2011). Oyster condition, infection rate, and reproductive state were no different from oysters 

sampled from areas not exposed to oil. Both oyster studies caution, however, that sample sizes were 

small and the findings of the study should not be extrapolated to all oysters in the GOM. Nonetheless, the 
4-92 Central Planning Area Lease Sales 235, 241, and 247 EIS

results indicate that oysters in the CPA should not have accumulated PAH or assimilated oil-derived C or 

N from the Deepwater Horizon oil spill either.

Many deepwater soft bottom benthic sites have been sampled by NRDA through visual 

documentation and sediment coring to assess the adverse effects of dispersed oil and drilling mud from 

the Deepwater Horizon explosion, oil spill, and response on these habitats. The information collected at 

site-specific locations will be used to model the extent of oiling in deepwater sediments (USDOC, 

NOAA, 2012a). This information has yet to be released.

Limited data are currently available on potential impacts of the Deepwater Horizon explosion, oil 

spill, and response on the soft bottom benthic communities in the CPA. This incomplete or unavailable 

information may be relevant to reasonably foreseeable significant impacts to soft bottom benthic 

communities. Relevant data on the status of soft bottom benthic communities after the Deepwater 

Horizon explosion, oil spill, and response may take years to acquire and analyze. Much of these data are 

being developed through the NRDA process, which may take years to complete. Little data from the 

NRDA process have been made available to date. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in the NEPA analysis of this Supplemental EIS, regardless 

of the cost or resources needed. BOEM has determined that this incomplete or unavailable information 

may be essential to a reasoned choice among alternatives for the reasons stated herein and in the 2012-

2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. In the place of this 

incomplete or unavailable information, BOEM’s subject-matter experts have used available scientifically 

credible evidence in this analysis and applied it using accepted scientific methods and approaches.

4.1.1.12.Marine Mammals

BOEM has reexamined the analysis for marine mammals presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for marine 

mammals presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

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

CPA proposed action are presented in the 2012-2017 WPA/CPA Multisale EIS, and updated information 

is provided in the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental 

contribution to the cumulative impacts is presented below. Any new information that has become 

available since those documents were published is presented below.

A detailed description of marine mammals can be found in Chapter 4.2.1.12.1 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.12 of the WPA 233/CPA 

231 Supplemental EIS.

Impacts of Routine and Accidental Events

The routine activities associated with proposed CPA Lease Sales 235, 241, and 247 that would 

potentially affect marine mammals include the following: the degradation of water quality from 

operational discharges; noise generated by aircraft, vessels, operating platforms, and drillships; vessel 

traffic; explosive structure removals; seismic surveys; and marine debris from service vessels and OCS 

structures. A detailed impact analysis of the routine impacts of proposed CPA Lease Sales 235, 241, and 

247 on marine mammals can be found in Chapter 4.2.1.12.2 of the 2012-2017 WPA/CPA Multisale EIS, 

and updated information is provided in Chapter 4.2.1.12 of the WPA 233/CPA 231 Supplemental EIS.

Some routine activities related to a CPA proposed action have the potential to have adverse, but not 

significant, impacts to marine mammal populations in the GOM. Impacts from vessel traffic, structure 

removals, and seismic activity could negatively impact marine mammals; however, when mitigated as 

required by BOEM and NMFS, these activities are not expected to have long-term impacts on the size and 

productivity of any marine mammal species or population. Most other routine activities are expected to 

have negligible effects.

Impact-producing factors associated with accidental events that may be associated with a CPA 

proposed action that could affect marine mammals include blowouts, oil spills, and spill-response 

activities. A detailed impact analysis of the accidental impacts that may be associated with proposed 
Description of the Environment and Impact Analysis 4-93

CPA Lease Sales 235, 241 and 247 on marine mammals can be found in Chapter 4.2.1.12.3 of the 2012-

2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.12 of the WPA 

233/CPA 231 Supplemental EIS.

Accidental events related to a CPA proposed action have the potential to have adverse, but not 

significant, impacts to marine mammal populations in the Gulf of Mexico. Accidental blowouts, oil 

spills, and spill-response activities may impact marine mammals in the Gulf of Mexico. Characteristics 

of impacts (i.e., acute vs. chronic impacts) depend on the magnitude, frequency, location, and date of 

accidents; characteristics of spilled oil; spill-response capabilities and timing; and various meteorological 

and hydrological factors.

Oil spills may cause chronic (long-term lethal or sublethal oil-related injuries) and acute (spill-related 

deaths occurring during a spill) effects on marine mammals. Long-term effects include decreases in prey 

availability and abundance because of increased mortality rates, change in age-class population structure 

because certain year-classes were impacted more by oil, decreased reproductive rate, and increased rate of 

disease or neurological problems from exposure to oil (Harvey and Dahlheim, 1994). The effects of 

cleanup activities are unknown, but increased human presence (e.g., vessels) could add to changes in 

marine mammal behavior and/or distribution, thereby additionally stressing animals and perhaps making 

them more vulnerable to various physiologic and toxic effects.

Even after the spill is stopped, oiling or deaths of marine mammals could still occur due to oil and 

dispersants persisting in the water, past marine mammal/oil or dispersant interactions, and ingestion of 

contaminated prey. The animals’ exposure to hydrocarbons persisting in the sea may result in sublethal 

impacts (e.g., decreased health, reproductive fitness, and longevity; behavioral effects; and increased 

vulnerability to disease) and some soft tissue irritation, respiratory stress from inhalation of toxic fumes, 

food reduction or contamination, direct ingestion of oil and/or tar, and temporary displacement from 

preferred habitats.

Summary and Conclusion

BOEM has reexamined the analysis for marine mammals presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for marine 

mammals presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS because of the available scientifically credible evidence in this analysis and based upon accepted 

scientific methods and approaches. The analysis and potential impacts detailed in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease 

Sale 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

The cumulative analysis considers past, ongoing, and foreseeable future human and natural activities

that may occur and adversely affect marine mammals in the same general area that may be affected by a 

CPA proposed action. The major potential impact-producing factors affecting protected marine mammals 

in the GOM as a result of cumulative OCS oil- and gas-related activities include marine debris, 

contaminant spills and spill-response activities, vessel traffic, noise, seismic surveys, and explosive 

structure removals. Non-OCS oil- and gas-related activities that may affect marine mammal populations 

include vessel traffic and related noise (including from commercial shipping and research vessels), 

military operations, commercial fishing, pollution, scientific research, and natural phenomena. Specific 

types of impact-producing factors considered in this cumulative analysis include noise from numerous 

sources, pollution, habitat degradation, vessel strikes, and ingestion and entanglement in marine debris.

OCS Oil- and Gas-Related Activities

The major impact-producing factors relative to a CPA proposed action are described below and in 

Chapter 4.2.1.12 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.12 of the WPA 233/CPA 231 Supplemental EIS. Chapters providing supportive material 

for the marine mammals analysis include Chapter 4.1.1.12 (description of marine mammals) of the 2012-
4-94 Central Planning Area Lease Sales 235, 241, and 247 EIS

2017 WPA/CPA Multisale EIS, updated information provided in Chapter 4.1.1.12 of the WPA 233/CPA 

231 Supplemental EIS, and Chapters 3.1.1.2 (exploration and delineation), 3.1.1.3 (development and 

production), 3.1.1.6 (noise), 3.1.2.1 (coastal impact-producing factors and scenario), and 3.2.1 (oil spills) 

of this Supplemental EIS. This Agency completed a Programmatic EA on G&G permit activities in the 

GOM (USDOI, MMS, 2004). The Programmatic EA includes a detailed description of the seismic 

surveying technologies, energy output, and operations, and it is hereby incorporated by reference.

Noise in the ocean has become a worldwide topic of concern, particularly in the last decade. The 

GOM is a very noisy place, and noise in the Gulf comes from a broad range of sources. Virtually all of 

the marine mammal species in the Gulf have been exposed to OCS industrial noise due to the rapid 

advance into GOM deep oceanic waters by the oil and gas industry in recent years; whereas, 20 years ago, 

the confinement of industry to shallower coastal and continental shelf waters generally only exposed two 

species of marine mammals (the bottlenose dolphin and the Atlantic spotted dolphin) to industry activities 

and the related sounds. Most marine mammal species in the Gulf, and particularly the deepwater

mammals, rely on echolocation for basic and vital life processes including feeding, navigation, and 

conspecific and mate communication. Noise levels that interfere with these basic functions could have 

impacts on individuals and populations. The OCS oil and gas industry’s operations contribute noise to 

the marine environment from several different operations. As noted below and in Chapter 4.2.1.12.2 of 

the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.12 of the WPA 233/CPA 231 Supplemental 

EIS, it is believed that most of the oil and gas industry-related noise is at lower frequencies than is 

detectable or in the sensitivity range of most of the GOM marine mammal species. However, most of the 

information on marine mammal hearing is inferred, and there are reports of species reacting to sounds that 

were not expected to be audible.

Industry noise sources include seismic operations, fixed platforms and drilling rigs, drilling ships, 

low-flying aircraft, vessel traffic, and explosive operations, particularly for structure removal. Chapter 

3.1.1.6 discusses the expected sources of many of these impacts for the OCS Program, as well as the 

expected sources from past, present, and future OCS oil and gas industry operations. Many other sources 

also contribute to the overall noise in the GOM. The dominant source of human sound in the sea is ship 

noise (Tyack, 2008). Both the noise from the vessel’s operation as well as the potential for ship strikes 

could potentially impact marine mammals. The primary sources of vessel noise are propeller cavitations, 

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 oil and 

gas industry 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. The GOM is a very active shipping area and supertankers are very common. Of the 

10 busiest ports in the United States, 7 are located in the Gulf of Mexico (USEPA, 2011e). Industry 

service boats are numerous and are expected to make 3,310-4,382 round trips in the GOM per year. 

Service vessels are a large contributor to ship noise; however, service boats are not nearly as large or as 

loud as commercial shipping vessels. Also, service vessels travel rapidly and, thus, an area is ensonified 

for only a brief time.

BOEM and BSEE issued NTL 2012-JOINT-G01, “Vessel Strike Avoidance and Injured/Dead 

Protected Species Reporting,” which provides guidance for vessel strike avoidance and reporting. This 

guidance should minimize the chance of marine mammals being subject to the increased noise level of an 

oil and gas service vessel in very close proximity. Aircraft overflights are another source of noise and can 

cause startle reactions in marine mammals, including rapid diving, change in travel direction, and 

dispersal of marine mammal groups. With approximately 1 million helicopter take offs/landings expected 

per year from activity related to past, proposed, and future lease sales, OCS oil and gas industry activity 

contributes greatly to this noise source. Although air traffic well offshore is limited, flight level minimum 

guidelines from NOAA and corporate helicopter policy should help mitigate the industry-related flight 

noise, although lower altitudes near shore and as the helicopter lands and departs from rigs could impact 

marine mammals in close proximity to the structures or shore bases. Occasional overflights are not 

expected to have long-term impacts on marine mammals.

Vessel strikes are a serious threat to marine mammals in the GOM. A collision between a marine 

mammal and a ship will result in injury and likely death. The increase in vessel traffic due to a CPA 

proposed action would increase the probability of a vessel strike and the injury or death of some animals. 

The increased vessel traffic may alter behavior of marine mammals by avoidance, displacement, or 

attraction to the vessel. However, those effects are expected to be short term. BOEM and BSEE issued 
Description of the Environment and Impact Analysis 4-95

NTL 2012-JOINT-G01, “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting,” which 

provides guidance for vessel strike avoidance and reporting in order to minimize the harassment of 

mammals by vessels approaching too closely. It also provides for the reporting of injured or dead 

protected species. Although OCS oil- and gas-related vessel traffic would be a major component of the 

cumulative vessel impacts, professional piloting and regulatory guidelines would minimize the impact of 

the OCS segment of vessel traffic.

The OCS oil and gas industry drilling impacts are discussed in Chapter 3.1.1. Although much of the 

focus is on industry operations in deep water, there is still interest and activity in more shallow and even 

coastal waters for oil and gas production. Similarly, explosive structure removals put considerable sound 

into the ocean, and these can occur in Federal or State waters. In 2005, this Agency petitioned NMFS for 

incidental-take regulations under the MMPA to address the potential injury and/or mortality of marine 

mammals that could result from the use of explosives during decommissioning activities. Similarly, this 

Agency initiated ESA section 7 consultation efforts with NMFS to cover potential explosive-severance 

impacts to threatened and endangered species such as sperm whales (and sea turtles). The consultation 

was completed in August 2006, and the final MMPA take rule was published in June 2008 (Federal 

Register (2008a). The mitigation, monitoring, and reporting requirements from the current ESA 

Biological Opinion/Incidental Take Statement and MMPA regulations mirror one another and allow 

explosive charges up to 500 lb (227 kg), internal and external placement, and both above-mudline and 

below-mudline detonations. The BOEMRE issued “Decommissioning Guidance for Wells and 

Platforms” (NTL 2010-G05) to offshore operators. This guidance specifies and references mitigation 

requirements in the new ESA and MMPA guidance and require trained observers to watch for protected 

species of sea turtles and marine mammals in the vicinity of the structures to be removed.

Seismic exploration is the source of the loudest, and perhaps most controversial, OCS oil and gas 

industry activity. Details on seismic impacts on marine mammals are given in the Chapter 4.2.1.12.2 of 

the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.12 of the WPA 233/CPA 231 Supplemental 

EIS, and complete information is included in the G&G Programmatic EA (USDOI, MMS, 2004). 

Seismic exploration is an integral part of oil and gas discovery, development, and production in the GOM. 

With technical advances that now allow extraction of petroleum from the ultra-deep areas of the Gulf, 

seismic surveys are routinely conducted in virtually all water depths of the western GOM, including the 

deep habitat of the endangered sperm whale. Noise and acoustic disturbance have been topics of great 

debate in the last several years, and there is general agreement that the use of sonar, particularly by the 

military, has in some cases been associated with very severe impacts to certain species of marine 

mammals in recent years. Seismic airgun sounds are often incorrectly lumped with sonar noise as sources 

of marine mammal disturbance. Although there are anecdotal associations between marine mammal 

disturbance and airgun noise, most of those have other factors occurring at the same time (i.e., sonar use) 

that may be responsible for any adverse impacts. However, seismic surveys have the potential to impact 

marine mammals. In 2003, NMFS published a notice of receipt of application for an incidental take 

authorization from this Agency, requesting comments and information on taking marine mammals 

incidental to conducting oil and gas exploration activities in the GOM (Federal Register, 2003). In 2004, 

NMFS published a notice of intent to prepare an EIS, notice of public meetings, and request for scoping 

comments for the requested authorizations (Federal Register, 2004). In April 2011, NMFS received a 

revised complete application from this Agency requesting an authorization for the take of marine 

mammals incidental to seismic surveys on the OCS in the GOM (Federal Register, 2011a). The National 

Marine Fisheries Service’s EIS has not been completed at this time. In response to terms and conditions 

in NMFS’s Biological Opinion for Lease Sale 184 in 2002, this Agency developed mitigations for the 

seismic industry that require, among other things, dedicated marine mammal observers aboard all seismic 

vessels, gradual ramp-up of the airgun array, and shutdowns of airgun firing if a whale gets within 500 m 

(1,640 ft) of an active airgun array. Although shutdowns are not extremely frequent, they do occur. Also, 

as reported in Chapter 4.2.1.12.1 of the 2012-2017 WPA/CPA Multisale EIS, current research by BOEM 

and partners did not detect avoidance of seismic vessels or airguns by sperm whales. Although that 

finding could be interpreted several ways, it is likely that the whales, which appear to generally remain in 

the northern Gulf year round, are habituated to seismic operations. Since the sperm whale is the only 

endangered cetacean (whale or dolphin) in the GOM, most of the research has focused on that species. 

However, other species may react very differently to seismic disturbances. Even with additional ongoing 

research, such changes in species abundance and distribution due to seismic disturbances would likely be 

very difficult to establish on a small scale. For the sperm whale, the most recent abundance for the GOM 
4-96 Central Planning Area Lease Sales 235, 241, and 247 EIS

population was estimated to be 763 individuals (Waring et al., 2013). Research has shown that sperm 

whales are distributed throughout the deeper waters of the northern GOM, not primarily in Mississippi 

Canyon as previously thought. With seismic surveys frequently conducted in the GOM, it is likely that 

there are few naive sperm whales (those that have not been exposed to seismic sound) in the northern 

Gulf. The GOM sperm whales have generally been smaller than sperm whales in other areas, and genetic 

research indicates a distinct stock or population that is almost exclusively females and immature males; 

mature males are thought to move into and out of the GOM. Observations of adult males are uncommon 

in the GOM (<10), yet calves are seen regularly. Reproduction is occurring in a highly industrialized 

environment, although stress, particularly at the individual animal level, is difficult to observe and 

measure. Over the long term, stress to a population could cause very significant adverse effects, 

including disease, reproductive failure, and population decline. Tools such as the satellite tag (s-tag) that 

allow the tracking of individual whales, and sometimes several individuals in a group, over the span of 

weeks and months may provide information on behavioral changes, as well as learning what is “typical” 

whale behavior.

Pollution of marine waters is another potentially adverse impact to marine mammals in the GOM. 

Information on drilling fluids and drill cuttings and produced waters that would be discharged offshore is 

discussed in Chapter 3.1.1.4. Effluents are routinely discharged into offshore waters and are regulated 

by the U.S. Environmental Protection Agency’s NPDES permits. Marine mammals may be periodically 

exposed to these discharges. Direct effects to marine mammals are expected to be sublethal. Indirect 

effects via food sources are not expected because of dilution and dispersion of offshore operational 

discharges. Another OCS oil and gas industry form of pollution is accidental oil spills. Impacts of these 

accidental events to marine mammals are discussed below and in Chapter 4.2.1.12.3 of the 2012-2017 

WPA/CPA Multisale EIS and Chapter 4.2.1.12 of the WPA 233/CPA 231 Supplemental EIS.

Marine debris is a serious concern in the ocean environment. Plastics in particular, and from many 

different sources, pose a threat to the environment and a serious threat to marine mammals. Ingestion of 

plastic can cause a digestive blockage and ultimately death for a marine mammal. Entanglement in 

anything from 6-pack rings to strapping bands to discarded monofilament nets can result in injury and 

very slow death for marine mammals. A wide variety of debris is commonly observed in the Gulf and it 

comes from both terrestrial and marine sources. Accidental release of debris from OCS activities is 

known to occur offshore, and ingestion of, or entanglement in, discarded material could injure or kill 

cetaceans. Sheavely (2007) reports that as much as 49 percent of marine debris is considered land-based. 

The offshore oil and gas industry was shown to contribute 13 percent of the debris found at Padre Island 

National Seashore in 1995 (Miller et al., 1995). Since that time, industry has implemented waste 

management programs and has greatly improved waste handling. More efficient gear packaging and 

better galley practices have significantly reduced the amount of waste generated offshore. The BSEE 

prohibits the disposal of equipment, containers, and other materials into coastal and offshore waters by 

lessees (30 CFR § 250.40). Prohibition of the discharge and disposal of vessel- and offshore structuregenerated garbage and solid waste items into both offshore and coastal waters was established January 1, 

1989, via the enactment of MARPOL, Annex V, Public Law 100-220 (101 Statute 1458), which the 

USCG enforces. BOEM 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 2012-

BSEE-G01).

In 2010, the Deepwater Horizon explosion occurred in Mississippi Canyon Block 252, and the 

resulting oil spill and related spill-response activities (including use of dispersants) have impacted marine 

mammals that have come into contact with oil and remediation efforts. According to NMFS’s website 

reports on stranded marine mammals during and after the Deepwater Horizon explosion, oil spill, and 

response, 171 marine mammals (the majority of which were deceased) have been collected as of April 17, 

2011 (USDOC, NMFS, 2013a). All marine mammals collected either alive or dead were found east of 

the Louisiana/Texas border. A recent study conducted as part of the NRDA process found strong 

evidence of petroleum hydrocarbon exposure and toxicity, some expected to result in death, in common 

bottlenose dolphins in Barataria Bay, Louisiana, an area that was heavily oiled during the Deepwater 

Horizon explosion and oil spill, as compared with common bottlenose dolphins in Sarasota Bay, Florida 

(Schwacke et al., 2013). Advances in oil-spill prevention technologies and safety requirements should 

greatly reduce the amount of oil that enters the marine environment accidentally. However, there is still 

the potential for an oil spill. Many small spills are estimated as a result of the OCS Program. The 

probability of a spill will decrease as the projected size of the spill increases. Marine mammals are likely 
Description of the Environment and Impact Analysis 4-97

to contact oil in the marine environment over their life span. However, because of dilution and 

weathering, such contact is expected to be sublethal in most situations. Indirect effects from the exposure 

of prey species to oil are also expected to be sublethal. Oil in the ocean can and does come from sources 

other than industry operations. Ships are known to illegally pump oily bilges into the environment. 

Mechanical failure on any type of vessel can lead to an oil spill, although these are usually small. Even 

natural seeps on the floor of the GOM can result in an oil slick or sheen on the surface (NRC, 2003).

An unusual mortality event (UME) is defined in the MMPA as “a stranding that is unexpected; 

involves a significant die-off of any marine mammal population; and demands immediate response.” The 

UME’s appear to be triggered by natural events (i.e., unusually cold weather and disease) but others are 

suspected to at least be indirectly caused by pollution of various contaminants. It is unclear at this time 

whether the UME occurring in the GOM is related partially, wholly, or not at all to the Deepwater

Horizon explosion, oil spill, and response. According to NMFS’s 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 NMFS as early as February 2010, several months prior to the Deepwater Horizon

explosion, oil spill, and response. However, the current data (Table 4-1) also show a marked increase in 

strandings during the Deepwater Horizon explosion, oil spill, and response and afterwards. According to 

the website, NMFS considers the investigation into the cause of the UME and the potential role of the 

Deepwater Horizon explosion, oil spill, and response to be “ongoing and no definitive cause has yet been 

identified for the increase in cetacean strandings in the northern Gulf in 2010 and 2011.” It is therefore 

unclear whether increases in stranded cetaceans during and after the Deepwater Horizon explosion, oil 

spill, and response period are or are not related to impacts from the Deepwater Horizon explosion, oil 

spill, and response and will likely remain unclear until NMFS completes its UME and NRDA evaluation 

processes.

Non-OCS Oil- and Gas-Related Activities

Non-OCS oil- and gas-related activities that may affect marine mammal populations include vessel 

traffic and related noise (including from commercial shipping, research vessels), military operations, 

commercial fishing, pollution, scientific research, and natural phenomena.

Other groups such as the military (U.S. Navy and USCG) and other Federal agencies (USEPA, COE, 

and NMFS), dredges, commercial fishermen, and recreational boaters operate vessels and contribute to 

the ambient noise in the Gulf. The COE also engages in some explosive and pile-driving operations that 

create loud but temporary noise. Such COE activities are consulted on with NMFS, and mitigations are 

included, often similar to the mitigations employed by BOEM in consultation with NMFS. Although air 

traffic well offshore is limited, the military maintains 11 military warning areas and 6 water test areas in 

the Gulf (Figure 2-2). Some commercial fisheries include aerial surveillance. Scientific research aerial 

surveys are occasionally scheduled over the GOM. Commercial and private aircraft also traverse the 

area. State oil and gas activities (Chapter 3.3.2) also create drilling and associated noise, particularly in 

Texas and Louisiana State waters. These effects are similar to those of OCS oil and gas operations 

discussed above.

Industry-related vessels are only a part of the shipping activity in the Gulf. All manner of commercial 

shipping vessels, commercial fishing vessels, military ships, research ships, recreational craft, and others 

are always present in the Gulf. Some factions of the boating public, mainly recreational fishermen and 

boaters, create adverse impacts by paying too much attention rather than not enough. Although most of 

these interactions are because of ignorance rather than malicious intent, 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. The presence of industry structure (platforms) in the deep 

waters of the Gulf may indirectly be encouraging these interactions. Recreational fishing vessels go much 

farther out to get to the improved fishing at OCS oil and gas structures. This also puts these vessels in 

oceanic marine mammal waters. Service-vessel crews that keep attention on the water and that 

intentionally avoid marine mammals should not pose a threat to marine mammal populations.

The Gulf 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 
4-98 Central Planning Area Lease Sales 235, 241, and 247 EIS

also the chance of entanglement by lines from crab traps to buoys. Gillnets, which have now been banned 

in many places around the Gulf, have been reported to take marine mammals. Reports of these impacts 

are uncommon.

Pollution in the ocean comes from many point and nonpoint 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 Gulf. 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). Since most of the 

marine mammals in the Gulf are oceanic dwellers that have the ability to alter their course depending on 

the surroundings, the impact of coastal and run-off pollution is greatly minimized as a result of dilution 

and dispersal. Primarily, the bottlenose dolphin and the manatee are most at risk for nearshore pollution. 

Bottlenose dolphins have been reported having very high levels of contaminants, including heavy metals, 

in tissue samples. Coastal dolphins generally have higher contaminant levels than offshore dolphins, 

which supports the dilution and dispersal theory. Prey species also affect the influence of pollution on 

marine mammals. Biomagnification in fish results in the generally higher contaminant levels of fisheating marine mammals over squid-eating species. Manatees are herbivores, but pollution and habitat 

degradation may impact the manatee. Manatees are exposed to pesticides by ingesting aquatic vegetation 

containing concentrations of these compounds. The propensity of manatees to aggregate at industrial and 

municipal outfalls also may expose them to high concentrations of contaminants. Antifouling bottom 

paint on the hulls of boats has been linked to the release of contaminants. 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.

Marine debris from non-OCS oil- and gas-related sources also has the potential to impact marine 

mammals. These impacts would not be different from those described above for OCS oil- and gas-related 

sources.

Scientific research can impact marine mammal species. BOEM has conducted numerous marine 

mammal research cruises, and permitted activities have included tagging and biopsy sampling. 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 could have the same impact with the same 

very loud noise as industry seismic work. 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 

Gulf, 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 markrecapture studies. This required the live capture and branding of dolphins. Both the U.S. Navy and the 

public-display industry took bottlenose dolphins from the Gulf 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.

Other activities may have adverse effects on marine mammals. Occasionally, numbers of marine 

mammals strand, either alive or already dead. Die-offs happen infrequently but can seriously deplete 

small, discreet stocks. The causes of die offs are not always well known and vary by event. Some appear 

to be triggered by natural events (i.e., unusually cold weather) but others are suspected to at least be 

indirectly caused by pollution of various 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 are being observed more frequently than in the past. A UME is 

defined under the MMPA as a “stranding that is unexpected, involves a significant die-off of any marine 

mammal population, and demands immediate response.” Several UME’s have been declared since 2010 

in the Gulf of Mexico. Some potential causes have been determined and an UME may have devastating 

effects on a marine mammal population depending on its extent and duration. More detail on UME’s can 

be found on NMFS’s website at http://www.nmfs.noaa.gov/pr/health/mmume/ (USDOC, NMFS, 2014a). 

Tropical storms and hurricanes are normal occurrences in the Gulf and along the coast. Generally, 

the impacts have been localized and infrequent. However, during the past 10 years, the GOM has been 

hit extremely hard by very powerful hurricanes. Few areas of the coast had not suffered some damage in 

2004 and 2005, and activities in the Gulf have also been severely impacted. In 2004, Hurricane Ivan took 

a large toll on oil and gas structures and operations in the Gulf 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. These storms 
Description of the Environment and Impact Analysis 4-99

caused damage to all five of the Gulf Coast States and damage to structures and operations both offshore 

and onshore. The actual impacts of these storms on the animals in the Gulf, and the listed species and 

critical habitat in particular, have not yet been determined and, for the most part, may remain very 

difficult to quantify. Examples of other impacts that may have affected species include oil, gas, and 

chemical spills from damaged and destroyed structures and vessels (although no major oil spills were 

reported, several lesser spills are known to have occurred), increased trash and debris in both offshore and 

inshore habitats, and increased runoff and silting from wind and rain. Not only are the impacts 

themselves difficult to assess but the seasonal occurrence of impacts from hurricanes is also impossible to 

predict. Generally, the far offshore species and the far offshore habitat are not expected to have been 

severely affected in the long term. However, species that occupy more nearshore or inshore habitats may 

have suffered more long-term impacts.

Summary and Conclusion

Cumulative impacts on marine mammals are 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) that may stress and/or weaken individuals of a local group or 

population and predispose them to infection from natural or anthropogenic sources (Harvey and 

Dahlheim, 1994). Disturbance (noise from vessel traffic and drilling operations) and/or exposure to 

sublethal levels of toxins and anthropogenic contaminants may stress animals, weaken their immune 

systems, and make them more vulnerable to parasites and diseases that normally would not be fatal 

(Harvey and Dahlheim, 1994). The net result of any disturbance will depend upon the size and 

percentage of the population likely to be affected, the ecological importance of the disturbed area, the 

environmental and biological parameters that influence an animal’s sensitivity to disturbance and stress, 

or the accommodation time in response to prolonged disturbance (Geraci and St. Aubin, 1980). As 

discussed in Appendix B, a low-probability catastrophic event could have population-level effects on 

marine mammals.

The effects of a CPA proposed action, when viewed in light of the effects associated with other past, 

present, and reasonably foreseeable future activities, may result in greater impacts to marine mammals

than before the Deepwater Horizon explosion, oil spill, and response; however, the magnitude of those 

effects cannot yet be determined. Nonetheless, operators are required to follow all applicable lease 

stipulations and regulations, as clarified by NTL’s, to minimize these potential interactions and impacts. 

The operator’s reaffirmed compliance with NTL 2012-JOINT-G01 (“Vessel Strike Avoidance and 

Injured/Dead Protected Species Reporting”) and NTL 2012-BSEE-G01 (“Marine Trash and Debris 

Awareness and Elimination”), as well as the limited scope, timing, and geographic location of a CPA 

proposed action, would result in negligible effects from the proposed drilling activities on marine 

mammals. In addition, NTL 2012-JOINT-G02, “Implementation of Seismic Survey Mitigation Measures 

and Protected Species Observer Program,” minimizes the potential of harm from seismic operations to 

marine mammals. These mitigations include onboard observers, airgun shut-downs for whales in the 

exclusion zone, ramp-up procedures, and the use of a minimum sound source. Therefore, no significant 

cumulative impacts to marine mammals would be expected as a result of the proposed exploration 

activities when added to the impacts of past, present, or reasonably foreseeable oil and gas development 

in the area, as well as other ongoing activities in the area.

Unavailable information on the effects to marine mammals from the UME and Deepwater Horizon

explosion, oil spill, and response (and thus, changes to the marine mammal baseline in the affected 

environment) makes an understanding of the cumulative effects less clear. Here, BOEM concludes that 

the unavailable information from these events may be relevant to foreseeable significant adverse impacts 

to marine mammals. 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 in the NEPA analysis of this 

Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable 

information, BOEM subject-matter experts have used available scientifically credible evidence in this 

analysis applied using accepted scientific methods and approaches. Nevertheless, a complete 
4-100 Central Planning Area Lease Sales 235, 241, and 247 EIS

understanding of the missing information is not essential to a reasoned choice among alternatives for this 

Supplemental EIS (including the No Action and Action alternatives) for the three main reasons listed 

below.

(1) The CPA is an active oil and gas region with ongoing (or the potential for) 

exploration, drilling, and production activities. The potential for effects from 

changes to the affected environment (post-Deepwater Horizon explosion, oil spill, 

and response), routine activities, accidental spills (including low-probability 

catastrophic spills), and cumulative effects remains whether or not the No Action or 

an Action alternative is chosen under this Supplemental EIS. Impacts on marine 

mammals from either smaller accidental events or low-probability catastrophic 

events will remain the same.

(2) Some marine mammal populations in the CPA do not generally travel throughout 

areas affected by spilled oil from the Deepwater Horizon explosion, oil spill, and 

response, and they would not be subject to a changed baseline or cumulative effects 

from the Deepwater Horizon explosion, oil spill, and response (e.g., coastal 

bottlenose dolphins resident in the CPA). Other marine mammals, such as Bryde’s 

whales and manatees, although potentially affected by the Deepwater Horizon 

explosion, oil spill, and response do not typically occur in the CPA.

(3) Other wide-ranging populations of marine mammals (e.g., sperm whales and killer 

whales) that may occur in the GOM and within areas affected by the spill are 

unlikely to have experienced population-level effects from the Deepwater Horizon

explosion, oil spill, and response given their wide-ranging distribution and 

behaviors.

Within the GOM, there is a long-standing and well-developed OCS Program (more than 50 years); 

there are no data to suggest that activities from the preexisting OCS Program are significantly impacting 

marine mammal populations. Therefore, in light of the above analysis for a CPA proposed action and its 

impacts, the incremental effect of a CPA proposed action on marine mammal populations is not expected 

to be significant when compared with non-OCS energy-related activities.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources (NOAA’s websites and the RestoreTheGulf.gov website), as 

well as recently published journal articles was conducted to determine the availability of recent 

information on marine mammals. 

On December 13, 2010, NMFS declared an UME for cetaceans (whales and dolphins) in the Gulf of 

Mexico. An UME is defined under the Marine Mammal Protection Act as a “stranding that is 

unexpected, involves a significant die-off of any marine mammal population, and demands immediate 

response.” Evidence of the UME was first noted by NMFS as early as February 2010, before the 

Deepwater Horizon explosion, oil spill, and response. As of February 2, 2014, a total of 1,086 cetaceans 

(6% stranded alive and 94% stranded dead) have stranded since the start of the UME, with a vast majority 

of these strandings between Franklin County, Florida, and the Louisiana/Texas border. After the initial 

response phase ended, six dolphins were killed incidental to fish-related scientific data collection and one 

dolphin was killed incidental to trawl relocation for a dredging project. More detail on the UME can be 

found on NMFS’s website (USDOC, NMFS, 2014a). 

In addition to investigating all other potential causes, scientists are investigating what role Brucella

may have played in the UME and this continues today. As of June 30, 2013, 27 out of 107 dolphins 

tested to date were positive or suspect positive for Brucella. 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. The total 

deaths for just one of the cetaceans, the bottlenose dolphin, currently well exceed the Potential Biological 

Removal. (The Potential Biological Removal is the product of minimum population size, one-half the 
Description of the Environment and Impact Analysis 4-101

maximum net productivity rate, and a recovery factor for endangered, depleted, threatened stocks, or 

stocks of unknown status relative to optimum sustainable population [Waring et al., 2013]). 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. The NMFS has documented 25 UME’s (17 of which involved 

cetaceans; the remaining 8 were specific to manatees only) that have occurred in the GOM for cetaceans 

since 1991.

According to their website, NMFS considers the investigation into the cause of the UME and the 

potential role of the Deepwater Horizon explosion, oil spill, and response to be “ongoing and no 

definitive cause has yet been identified for the increase in cetacean strandings in the northern Gulf from 

2010 to the present.” It is therefore unclear whether increases in stranded cetaceans during and after the 

Deepwater Horizon explosion, oil spill, and response period are or are not related to impacts from the

Deepwater Horizon explosion, oil spill, and response, and it will likely remain unclear until NMFS 

completes its UME and NRDA evaluation processes.

On May 9, 2012, NOAA declared an UME for bottlenose dolphins in five Texas counties (UME 

No. 56). The UME lasted from November 2011 through March 2012, when 123 bottlenose dolphins 

stranded in Aransas, Calhoun, Kleberg, Galveston, and Brazoria Counties in Texas. Of the 123 animals 

stranded, only 4 were found alive. Preliminary findings included infection in the lung, poor body 

condition, and discoloration of the teeth; in four animals, a black/grey, thick mud-like substance in the 

stomachs was found. The strandings were coincident with a harmful algal bloom of Karenia brevis that 

started in September 2011 in southern Texas, but researchers have not determined that was the cause of 

the event. Currently, there are no red tide blooms occurring in the region, and stranding rates have 

returned to normal levels (USDOC, NMFS, 2013b). 

As of October 3, 2013, a red-tide event in southwest Florida has claimed 288 manatees since first 

detecting the red tide bloom in late September 2012. Although results are preliminary, this is 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, 2013). Research into the 

causes of these deaths is currently ongoing and undetermined for UME No. 58 (Florida). A previous 

UME in 2011 (No. 52) was caused by ecological factors. A UME (No. 59) was declared in January 2013 

for bottlenose dolphins on the East Coast of Florida, the cause of which is still undetermined. Necropsies 

performed found most of the dolphins were emaciated and the timing coincided with the West Coast’s red 

tide-caused UME of manatees. There have been three separate manatee sitings near oil rigs in the CPA in 

water depths as great as 1,828 m (6,000 ft) (Epperson, official communication, 2013). Per the guidance 

provided in 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.

The final determinations on damages to marine mammal resources from the Deepwater Horizon

explosion, oil spill, and response will ultimately be made through the NRDA process. The Deepwater 

Horizon explosion, oil spill, and response will ultimately allow a better understanding of any realized 

effects from such a low-probability catastrophic spill. However, the best available information on 

impacts to marine mammals does not yet provide a complete understanding of the effects of the oil spill 

and active response/cleanup activities from the Deepwater Horizon explosion, oil spill, and response on 

marine mammals as a whole in the GOM and whether these impacts reach a population level. For 

example, although there has been a study published from the NRDA process regarding the possible 

effects from the Deepwater Horizon oil spill on Barataria Bay bottlenose dolphins, there were no effects 

detected on the Sarasota Bay bottlenose dolphins; therefore, it would be difficult to use this information to 

conclude anything different for the overall bottlenose dolphin population in the GOM (Schwacke et al., 

2013). There is also an incomplete understanding of the potential for population-level impacts from the 

ongoing UME.

Here, BOEM concludes that the unavailable information from these events may be relevant but not 

necessarily essential to reasonably foreseeable significant adverse impacts to marine mammals. In some 

specific cases, such as with bottlenose dolphins as noted below, the unavailable information may also be 

relevant to a reasoned choice among the alternatives based on the discussion below. The cost of obtaining 

data on the effects from the UME and/or Deepwater Horizon explosion, oil spill, and response are 

exorbitant; duplicative of efforts already being undertaken as part of the UME and NRDA; and would 

likewise take years to acquire and analyze through the existing NRDA and UME processes. Further, 

impacts from the Deepwater Horizon explosion, oil spill, and response may be difficult or impossible to 
4-102 Central Planning Area Lease Sales 235, 241, and 247 EIS

discern from other factors. For example, even 20 years after the Exxon Valdez spill, long-term impacts to 

marine mammal populations were still being investigated (Matkin et al., 2008). Therefore, it is not 

possible for BOEM to obtain this information within the timeline contemplated in the NEPA analysis of 

this Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or 

unavailable information, BOEM subject-matter experts have used available scientifically credible 

evidence in this analysis and applied it using accepted scientific methods and approaches. The 2012-2017 

WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, and EPA 225/226 EIS (USDOI, 

BOEM, 2013b) have further details on sperm whales, Bryde’s whales, bottlenose dolphins, and manatees.

4.1.1.13. Sea Turtles

BOEM has reexamined the analysis for sea turtles presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented below. No 

new significant information was discovered that would alter the impact conclusion for sea turtles 

presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The 

analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the 

WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

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

CPA proposed action are presented in the 2012-2017 WPA/CPA Multisale EIS, and updated information 

is provided in the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental 

contribution to the cumulative impacts is presented below. Any new information that has become 

available since those documents were published is presented below.

A detailed description of loggerhead, Kemp’s ridley, hawksbill, green, and leatherback sea turtles can 

be found in Chapter 4.2.1.13.1 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.13 of the WPA 233/CPA 231 Supplemental EIS. The FWS and NMFS share 

Federal jurisdiction for sea turtles under the ESA. The FWS has responsibility for sea turtles (i.e., eggs, 

hatchlings, and nesting turtles) on the nesting beaches. The NMFS has jurisdiction for sea turtles in the 

marine environment.

Impacts of Routine and Accidental Events

The routine activities associated with proposed CPA Lease Sales 235, 241, and 247 that would 

potentially affect sea turtles include the following: the degradation of water quality resulting from 

operational discharges; noise generated by helicopter and vessel traffic, platforms, drillships, and seismic 

exploration; vessel collisions; and marine debris generated by service vessels and OCS oil- and gasrelated facilities. A detailed impact analysis of the routine impacts of proposed CPA Lease Sales 235, 

241, and 247 on sea turtles can be found in Chapter 4.2.1.13.2 of the 2012-2017 WPA/CPA Multisale 

EIS, and updated information is provided in Chapter 4.2.1.13 of the WPA 233/CPA 231 Supplemental 

EIS.

Because of the mitigations (e.g., BOEM and BSEE proposed compliance with NTL’s) discussed in 

the 2012-2017 WPA/CPA Multisale EIS, routine activities (e.g., operational discharges, noise, vessel 

traffic, and marine debris) related to a CPA proposed action are not expected to have long-term adverse 

effects on the size and productivity of any sea turtle species or populations in the northern Gulf of 

Mexico. Lethal effects could occur from chance collisions with OCS oil- and gas-related service vessels 

or ingestion of accidentally released plastic materials from OCS vessels and facilities. However, there 

have been no reports to date on such incidences. Most routine OCS oil- and gas-related activities are 

expected to have sublethal effects that are not anticipated to rise to the level of significance.

Impact-producing factors associated with accidental events that may be associated with a CPA 

proposed action that could affect sea turtles include blowouts, oil spills, and spill-response activities. A 

detailed impact analysis of the accidental impacts that may be associated with proposed CPA Lease Sales 

235, 241, and 247 on sea turtles can be found in Chapter 4.2.1.13.3 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.13 of the WPA 233/CPA 231 

Supplemental EIS.

Accidental blowouts, oil spills, and spill-response activities resulting from a CPA proposed action 

have the potential to impact small to large numbers of sea turtles in the GOM, depending on the 

magnitude and frequency of accidents, the ability to respond to accidents, the location and date of 
Description of the Environment and Impact Analysis 4-103

accidents, and various meteorological and hydrological factors. Impacts on sea turtles from smaller 

accidental events are likely to affect individual sea turtles in the area, but they are unlikely to rise to the 

level of population effects (or significance) given the size and scope of such spills. Further, the potential 

remains for smaller accidental spills to occur in a CPA proposed action area, regardless of any alternative 

selected under this Supplemental EIS, given that it is an active oil and gas region with either ongoing or 

the potential for exploration, drilling, and production activities.

Summary and Conclusion

BOEM has reexamined the analysis for sea turtles presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented above. No 

new significant information was discovered that would alter the impact conclusion for sea turtles 

presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS because 

of the available scientifically credible evidence in this analysis and based upon accepted scientific 

methods and approaches. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA 

Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA 

Lease Sales 235, 241, and 247. 

Cumulative Impacts

Background/Introduction 

This cumulative analysis considers the effects of impact-producing factors related to a CPA 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 CPA proposed 

actions.

OCS Oil- and Gas-Related Impacts 

The major impact-producing factors resulting from cumulative OCS oil- and gas-related activities 

associated with a CPA proposed action that may affect loggerhead, Kemp’s ridley, hawksbill, green, and 

leatherback turtles and their habitats include marine debris, contaminant spills and spill-response 

activities, vessel traffic, noise, seismic surveys, and explosive structure removals. Major impactproducing factors related to a CPA proposed action that may occur are reviewed in detail in Chapter 

4.1.1.13. Chapters providing supporting material for the sea turtle analysis include Chapters 4.1.1.1 (air 

quality), 4.1.1.2.1 and 4.1.1.2.2 (water quality), 4.1.1.3 (coastal barrier beaches and associated dunes), 

4.1.1.5 (seagrass communities), 3.1.1 (offshore impact-producing factors and scenario), 3.1.2 (coastal 

impact-producing factors and scenario), 3.2 (impact-producing factors and scenario—accidental events), 

3.3 (cumulative activities scenario), and 5.7 (Endangered Species Act). The cumulative impact of these 

ongoing OCS oil- and gas-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 gasrelated 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.

Marine Debris

Sea turtles may be impacted by marine debris, whatever its source. Trash and flotsam generated by 

the oil and gas industry and other users of the Gulf (Miller and Echols, 1996) is transported around the 

Gulf and Atlantic via oceanic currents (Plotkin and Amos, 1988; Hutchinson and Simmonds, 1992). 

Turtles that consume or become entangled in trash or flotsam may become debilitated or die (Heneman 

and the Center for Environmental Education, 1988). While non-OCS oil- and gas-related monofilament 

debris is the most common entanglement debris, floating plastics and other debris, such as petroleum 

residues drifting on the sea surface, accumulate in Sargassum drift lines commonly inhabited by hatchling 

sea turtles (refer to Chapter 4.1.1.8 for Sargassum impacts). These materials could be toxic. In a review 

of worldwide sea turtle debris ingestion and entanglement, Balazs (1985) found that tar was the most 

common item ingested. A recent literature and data synthesis by Schuyler et al. (2013) found that smaller 

individuals in the oceanic life stage are more likely to ingest debris than are individuals foraging in 
4-104 Central Planning Area Lease Sales 235, 241, and 247 EIS

coastal areas; likewise, species that feed primarily on plants or gelatinous zooplankton (“jellyfish”) are 

more likely to ingest debris than carnivorous species. Ingestion of plastics sometimes interferes with food 

passage, respiration, and buoyancy and could reduce the fitness of a turtle or result in death (Carr, 1987; 

USDOC, NOAA, 1988; Heneman and the Center for Environmental Education, 1988; Lutz and AlfaroShulman, 1992). The BSEE regulate the disposal of equipment, containers, and other materials into 

offshore waters by lessees (30 CFR § 250.300). In addition, MARPOL Annex V (P.L. 100-220; 101 

Statute 1458) prohibits the disposal of plastics at sea or in coastal waters.

The BSEE proposes compliance with the guidance provided in NTL 2012-BSEE-G01, “Marine Trash

and Debris Awareness and Elimination,” which should appreciably reduce the likelihood of sea turtles

encountering marine debris from the proposed activity.

Effluents are routinely discharged into offshore waters and are regulated by the U.S. Environmental 

Protection Agency’s NPDES permits. Most operational discharges are diluted and dispersed when 

released in offshore areas and, due to USEPA’s permit regulations on discharges, are considered to have 

little effect (API, 1989; Kennicutt, 1995). Any potential that might exist for impact from drilling fluids 

would more likely be indirect, either by impact on prey items or possibly through ingestion via the food 

chain (API, 1989). Contaminants in drilling mud discharge may biomagnify and bioaccumulate in the 

trophic system, which may kill or debilitate important prey species of sea turtles or lower trophic level 

species. This could ultimately reduce reproductive fitness or survival in individual sea turtles.

Coastal Infrastructure and Pipelines 

Structure installation and removal, pipeline placement, dredging, and water quality degradation may 

adversely affect sea turtle foraging habitat through destruction of seagrass beds and live bottom

communities used by sea turtles (Gibson and Smith, 1999). Sea turtles, primarily loggerheads, in the 

GOM are known to occur regularly within the vicinity of oil and gas platforms (Hart et al., 2013). These 

structures provide habitat and foraging opportunities for subadult and adult sea turtles, which may 

enhance the recovery of some turtle populations.

Pollution 

Since sea turtle habitat in the Gulf includes both inshore and offshore areas, sea turtles are likely to 

encounter spills that may be related to OCS oil- and gas-related development activities or other sources. 

Oil-spill estimates project that there will be numerous, frequent, small spills; many, infrequent, 

moderately sized spills; and infrequent large spills occurring in coastal and offshore waters from 2012 to 

2050 (Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS). The probability that a sea turtle is 

exposed to hydrocarbons resulting from a spill extends well after the oil spill has dispersed from its initial 

aggregated mass. Oil spills can adversely affect sea turtles by toxic ingestion or blockage of the digestive 

tract, inflammatory dermatitis, ventilatory disturbance, disruption or failure of salt gland function, red 

blood cell disturbances, immune responses, and displacement from important habitat areas (Witham, 

1978; Vargo et al., 1986; Lutz and Lutcavage, 1989; Lutcavage et al., 1995). Sea turtles may become 

entrapped by tar and oil slicks and rendered immobile (Witham, 1978; Plotkin and Amos, 1988). In the 

past, tanker washings were a major source of oil in GOM waters (Van Vleet and Pauly, 1987). Although 

habitat disturbances may be temporary, chronic exposure to or ingestion of oil may result in illness or 

depressed fitness. Hatchling and juvenile turtles are particularly vulnerable to contacting or ingesting oil 

because currents that concentrate oil spills also form aggregates of Sargassum and other floating material 

that provide habitat in which these turtles are sometimes found (Carr, 1980; Collard and Ogren, 1990; 

Witherington, 1994). There is also evidence that sea turtles feed in surface convergence lines, which 

could prolong their contact with viscous weathered oil that becomes concentrated in these zones (Witham, 

1978; Hall et al., 1983). Fritts and McGehee (1982) noted that sea turtle eggs were damaged by contact 

with weathered oil released from the 1979 Ixtoc I spill. Skin damage in turtles can result in acute or 

irritant dermatitis; a break in the skin barrier could act as a portal of entry for pathogenic organisms, 

leading to infection and debilitation (Vargo et al., 1986). Captive turtles exposed to oil either reduced the 

amount of time spent at the surface, possibly avoiding oil, or became agitated and demonstrated short 

submergence levels (Lutcavage et al., 1995). Sea turtles sometimes pursue and swallow tarballs, and 

there is no conclusive evidence that wild turtles can detect and avoid oil (Odell and MacMurray, 1986; 

Vargo et al., 1986). A loggerhead turtle sighted during an aerial survey in the GOM surfaced repeatedly 
Description of the Environment and Impact Analysis 4-105

within a surface oil slick for over an hour (Lohoefener et al., 1989). Oil might have an indirect effect on 

the behavior of sea turtles. Oil fouling of a nesting area may disturb the imprinting of hatchling turtles or 

confuse turtles during their return migration after a 6- to 8-year absence (Geraci and St. Aubin, 1985). 

The effect on reproductive success could therefore be significant.

When an oil spill occurs, the severity of effects and the extent of damage to sea turtles is dependent 

on geographic location, oil type, oil dosage, impact area, oceanographic conditions, and meteorological 

conditions (NRC, 1985). Eggs, hatchlings, and small juveniles are particularly vulnerable upon contact 

(Fritts and McGehee, 1982; Lutz and Lutcavage, 1989). Potential toxic impacts to embryos will depend 

on the type of oil and degree of weathering, type of beach substrate, and especially upon the 

developmental stage of the embryo. Although many observed injuries and impacts to sea turtles were 

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).

Oil-spill and response activities, such as vehicular and vessel traffic in coastal areas of seagrass beds 

and live bottom communities, can alter sea turtle habitat and displace sea turtles from these areas. Effects 

on seagrass and reef communities have been noted (reviewed by Coston-Clements and Hoss, 1983). 

Impacting factors include artificial lighting from night operations, booms, machine and human activity, 

equipment on beaches and in intertidal areas, sand removal and cleaning, and changed beach landscape 

and composition. Some resulting impacts from cleanup could include interrupted or deferred nesting, 

crushed nests, entanglement in booms, and increased mortality of hatchlings because of predation during 

the extended time required to reach the water (Newell, 1995; Lutcavage et al., 1997; Witherington, 1999). 

The strategy for cleanup operations should vary depending on season, recognizing that disturbance to 

nests may be more detrimental than oil (Fritts and McGehee, 1982). Due to the Oil Pollution Act of 1990 

(Chapter 1.3), these areas are expected to receive individual consideration during oil-spill cleanup. 

Required oil-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. Accidental spills as a result of a low-probability catastrophic event are discussed in 

Appendix B. 

Vessel Strikes

Sea turtles must surface to breathe and may spend time at the surface for a variety of life-history 

functions. Collisions between service vessels or barges and sea turtles would likely cause fatal injury to 

the sea turtle. The speed of the vessel is correlated to the likelihood of strike; turtles are less likely to 

actively avoid or respond to the approach of a vessel moving at higher speeds (Hazel et al. 2007). Vessel 

traffic, particularly supply boats running from shore bases to offshore structures, is one of the industry 

activities included in a CPA proposed action. It is projected that 70,725-90,675 OCS oil- and gas-related, 

service-vessel round trips would occur annually in support of OCS oil- and gas-related activities in the 

CPA (Table 3-4). In the entire OCS, 82,750-109,550 service-vessel trips would occur annually (Table 

3-3). It is important to note that these numbers take into account all of the activities projected to occur 

from past, proposed, and future lease sales. In response to the terms and conditions of previous NMFS’s 

Biological Opinions, and in an effort to further minimize the potential for vessel strikes, BOEM and 

BSEE issued NTL 2012-JOINT-G01, “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting,” which clarifies 30 CFR § 550.282 and 30 CFR § 250.282 and provides NMFS guidelines for 

monitoring procedures related to vessel strike avoidance measures for sea turtles and other protected 

species.

Increased vessel traffic in the GOM increases the probability of sea turtle ship strikes. Regions of 

greatest concern may be those with high concentrations of recreational boat traffic, such as the many 

coastal bays in the GOM. Potential adverse effects from Federal vessel operations in the CPA proposed 

action area include operations of the U.S. Navy and USCG, which maintain the largest Federal vessel 

fleets; USEPA; NOAA; and COE. The NMFS has conducted formal consultations with USCG, U.S. 

Navy, NOAA, and other Federal agencies, including BOEM, on the activities of their vessels or the 

vessels considered part of any permitted activity. The NMFS has recommended conservation measures 

for operations of agency, contract, or private vessels to minimize impacts on listed species. However, 

these actions represent the potential for some level of interaction and, in some cases, conservation 

measures only apply to areas outside the CPA proposed action area. Thus, operations of vessels by 

Federal agencies within the CPA proposed action area (i.e., U.S. Navy, NOAA, USEPA, and COE) may 
4-106 Central Planning Area Lease Sales 235, 241, and 247 EIS

adversely affect sea turtles. However, the in-water activities of some of those agencies are limited in 

scope, as they operate a limited number of vessels or are engaged in research/operational activities that 

are unlikely to contribute a large amount of risk. (The NMFS reported in 2002 that, at that time, there 

were 14 active scientific research permits for sea turtles.) 

Noise

Noise from service-vessel and helicopter traffic may cause a startle reaction from sea turtles and 

produce temporary stress (NRC, 1990). Helicopter traffic would occur on a regular basis. It is projected 

that 594,500-1,112,500 OCS oil- and gas-related helicopter operations (take-offs and landings) would

occur annually in the support of OCS oil- and gas-related in the CPA (Table 3-4). In the entre OCS, 

717,750-1,376,625 helicopter trips would occur annually (Table 3-3). The Federal Aviation 

Administration’s Advisory Circular 91-36D (September 17, 2004) encourages pilots to maintain higher 

than minimum altitudes over noise-sensitive areas. The OCS oil- and gas-related helicopters are not the 

only aircraft that fly over the coastal and offshore areas.

Other sound sources potentially impacting sea turtles include seismic surveys and drilling noise. The 

potential impacts of anthropogenic sounds on sea turtles include physical auditory effects (temporary 

threshold shift), behavioral disruption, long-term effects, masking, and adverse impacts on prey species. 

Noise-induced stress has not been studied in sea turtles. Seismic surveys use airguns to generate sound 

pulses, which are a more intense sound than other nonexplosive sound sources. Loggerhead sea turtles in 

the Mediterranean Sea showed a startle response associated with airgun operation, with 57 percent of 

observed individuals diving upon or before reaching the airgun array. Of the observed individuals, 

7 percent dove immediately after the airgun shot (DeRuiter and Doukara, 2012). Seismic activities are 

expected to be primarily an annoyance to sea turtles and cause a short-term behavioral response. 

However, sea turtles are included in the mitigations required of all seismic vessels operating in the GOM, 

as stated in NTL 2012-JOINT-G02, “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program,” which minimizes the potential of harm from seismic operations to 

sea turtles. These mitigations include onboard observers, airgun shut-downs for whales in the exclusion 

zone, ramp-up procedures, and the use of a minimum sound source.

It is expected that drilling noise will periodically disturb and affect turtles in the GOM. Based on the 

conclusions of Lenhardt et al. (1983) and O’Hara and Wilcox (1990), low-frequency sound transmissions 

(such as those produced by operating platforms) could cause increased surfacing and deterrence behavior 

from the area near the sound source.

Explosive discharges, such as those used for BSEE and COE structure removals, can cause injury to 

sea turtles (Duronslet et al., 1986). Although sea turtles far from the site may suffer only disorientation, 

those near detonation sites could sustain fatal injuries. 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. An estimated 707-1,006 explosive structure removals 

are projected to occur in the CPA between 2012 and 2051 (Table 3-4). 

To minimize the likelihood of removals occurring when sea turtles may be nearby, BSEE issued 

guidelines for explosive platform removal to offshore operators. These guidelines include daylightlimited detonation, staggered charges, placement of charges 5 m (15 ft) below the seafloor, and pre- and 

post-detonation surveys of surrounding waters. With these existing protective measures (NMFS’s 

Observer Program and daylight-only demolition) in place, the “take” of sea turtles during structure 

removals has been limited. This Agency published a Programmatic EA on decommissioning operations 

(USDOI, MMS, 2005) that, in part, addresses the potential impacts of explosive and nonexplosive 

severance activities on OCS oil- and gas-related resources, particularly upon marine mammals and sea 

turtles. Pursuant to 30 CFR part 250 subpart Q, operators must obtain a permit from BSEE before 

beginning any platform removal or well-severance activities. During the review of the permit 

applications, terms and conditions of the August 2007 NMFS Biological Opinion/Incidental Take

Statement are implemented for the protection of marine protected species and to reduce the possible 

impacts from any potential activities resulting from a CPA proposed action.

In 30 CFR part 250 subpart B, BSEE requires operators of Federal oil and gas leases to meet the 

requirements of the ESA. The regulation outlines the environmental, monitoring, and mitigation 

information that operators must submit with plans for exploration, development, and production. This 
Description of the Environment and Impact Analysis 4-107

regulation requires OCS oil- and gas-related activities to be conducted in a manner that is consistent with 

the provisions of the ESA. Actual sea turtle impacts from explosive removals in recent years have been 

small. The updated pre- and post-detonation mitigations should ensure that injuries remain extremely 

rare. NTL 2010-G05, “Decommissioning Guidance for Wells and Platforms,” offers further guidance. 

Non-OCS Oil and Gas-Related Activities

Non-OCS oil- and gas-related activities that may affect sea turtle populations include State oil and gas 

activities, vessel traffic and related noise (including from commercial shipping, research vessels), military 

operations, commercial fishing, and pollution. Non-OCS oil- and gas-related related activities include 

historic overexploitation, commercial fishery interactions, habitat loss, dredging, pollution, vessel strikes, 

and pathogens. The Gulf Coast is a well-populated and growing area, and development of previously 

unusable land for residential and commercial purposes is common. Recreational boating and watercraft 

use may threaten individuals and their habitat. Increased human populations often result in increased 

runoff and dumping. Many areas around the Gulf already suffer from very high contaminant counts due 

to river and coastal runoff and discharges. Contaminants may accumulate in species or in prey species.

Dredge-and-fill activities occur in many of the coastal areas inhabited by sea turtles. Operations 

range in scope from propeller dredging (scarring) by recreational boats to large-scale navigation dredging 

and fill for land reclamation. Dredging operations affect turtles through accidental take and habitat 

degradation. The construction and maintenance of Federal navigation channels has been identified as a 

source of sea turtle mortality. Hopper dredges move relatively rapidly (compared with sea turtle 

swimming speeds) and can entrain and kill these species, presumably as the drag arm of the moving 

dredge overtakes the slower 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). In addition to direct take, channelization of the inshore and nearshore areas can degrade 

foraging and migratory habitats via sediment disposal, degraded water quality/clarity, and altered current 

flow.

Construction, vehicle traffic, beachfront erosion, and artificial lighting are activities that disturb sea 

turtles or their nesting beaches (Raymond, 1984; Garber, 1985). Traffic may compress nests, and beach 

cleaning may compact or destroy nests, lowering 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 of nesting beaches results in the loss of nesting habitat. 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 delay their entry into the sea, thereby increasing their 

vulnerability to terrestrial predators. 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 (discussed by Mrosovsky et al., 1995). Increased human 

activities, such as organized turtle watches, on nesting beaches may affect nesting activity (Fangman and 

Rittmaster, 1994; Johnson et al., 1996).

Sea turtles entering coastal or inshore areas have been affected by entrainment in the cooling water 

systems of electrical generating plants (NRC, 1990). At the St. Lucie nuclear power plant at Hutchinson 

Island, Florida, large numbers of green and loggerhead turtles have been captured in the seawater intake 

canal in the past several years. Annual capture levels from 1994 to 1997 ranged from almost 200 to 

almost 700 green turtles and from about 150 to over 350 loggerheads. Almost all of the turtles were 

caught and released alive; NMFS estimated the survival rate at 98.5 percent or greater. Other power 

plants in Florida, Texas, and North Carolina have also reported low levels of sea turtle entrainment. An 

offshore intake structure may appear as a suitable resting place to some turtles, and these turtles may be 

subsequently drawn into a cooling system (Witham, 1995). Feeding leatherbacks may follow large 

numbers of jellyfish into the intake (Witham, 1995). Deaths can result from injuries sustained in transit 

through the intake pipe, from drowning in the capture nets, and perhaps from causes before entrainment. 

Thermal effluents from power plants may cause hatchlings to become disoriented and reduce their 
4-108 Central Planning Area Lease Sales 235, 241, and 247 EIS

swimming speed (O’Hara, 1980). These effluents may also degrade seagrass and reef habitats (reviewed 

by Coston-Clements and Hoss, 1983).

Sand mining, beach renourishment, and oil-spill cleanup operations may remove sand from the littoral 

zone and temporarily disturb onshore sand transport, potentially disturbing nesting activities. The main 

causes of permanent nesting beach loss within the GOM are the reduction of sediment transport, rapid 

rate of relative sea-level rise, coastal construction and development, and recreational use of accessible 

beaches near large population centers. Crain et al. (1995) reviewed the literature on sea turtles and beach 

nourishment and found certain problems repeatedly identified. For nesting females, characteristics 

induced by nourishment can cause (1) beach compaction, which may decrease nesting success, alter nestchamber geometry, and alter nest concealment; and (2) escarpments, which can block turtles from 

reaching nesting areas. For eggs and hatchlings, nourishment can decrease survivorship and affect 

development by altering beach characteristics such as sand compaction, gaseous environment, hydric 

environment, contaminant levels, nutrient availability, and thermal environment. Additionally, nests can 

be covered with excess sand if beach nourishment occurs in areas with incubating eggs.

BOEM has evaluated the use of sand resources for levee, beach, and barrier island restoration 

projects. Between 1995 and 2013, this Agency provided over 77 million cubic yards of OCS sand for 

42 coastal projects, restoring over 370 km (230 mi) of national coastline. As the demand for sand for 

shoreline protection increases, OCS sand and gravel has become an increasingly important resource. For 

example, the Louisiana Coastal Area’s Ecosystem Restoration Study estimated that about 60 million 

cubic yards of OCS sand from Trinity Shoal, Ship Shoal, and other sites will be needed for barrier island 

and shoreline restoration projects in the next decade (U.S. Dept. of the Army, COE, 2004). Use of these 

resources will require coordination with BOEM for appropriate noncompetitive negotiated agreements. 

Sea turtles are included in the potential impacts identified for sand dredging projects under analyses and 

consultations that are separate from this Supplemental EIS. Based on the outcomes of these, required 

mitigating measures are included as stipulations in the negotiated agreements 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.

Human consumption of turtle eggs, meat, or byproducts occurs worldwide and depletes turtle 

populations (Cato et al., 1978; Mack and Duplaix, 1979). Commercial harvests are no longer permitted 

within continental U.S. waters, and Mexico has banned such activity (Aridjis, 1990). Since sea turtles are 

highly migratory species, the taking of turtles in subsistence and commercial sea turtle fisheries is still a 

concern.

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 (Hillestad et al., 1974; 

Stoneburner et al., 1980; Davenport et al., 1990), pesticides (Thompson et al., 1974; Clark and Krynitsky, 

1980; Davenport et al., 1990), and other toxins (Lutz and Lutcavage, 1989) in their tissues. 

Organochlorine pollutants have been documented in eggs, juveniles, and adult turtles (Rybitski et al., 

1995). Not all species accumulate residues at the same rate; for instance, loggerheads consistently have 

higher levels of both PCB’s (polychlorinated biphenyls) and DDE (dichloro-diphenyldichloro-ethylene) 

than green turtles, and it has been hypothesized that the variation is because of dietary differences 

(George, 1997). Contaminants could stress the immune system of turtles or act as carcinogens indirectly 

by disrupting neuroendocrine functions (Colborn et al., 1993). In some marine mammals, chronic 

pollution has been linked with immune suppression, raising a similar concern for sea turtles.

The OCS oil- and gas-related helicopters are not the only aircraft that fly over the coastal and offshore 

areas. The air space over the GOM is used extensively by the Dept. of Defense for conducting various 

air-to-air and air-to-surface operations. Eleven military warning areas and six water test areas are located 

within the Gulf, as stated in NTL 2009-G06, “Military Warning and Water Test Areas” (Figure 2-1). 

Additional activities, including vessel operations and ordnance detonation, also may affect sea turtles. 

Private and commercial air traffic also traverse these areas and have the potential to cause impacts to sea 

turtles.

Numerous commercial and recreational fishing vessels also use these areas. Tanker imports and 

exports of crude and petroleum products into the GOM are projected to increase. Crude oil will continue 

to be tankered into the Gulf for refining from Alaska, California, and the Atlantic. Recreational pursuits 

can have an adverse effect on sea turtles through propeller and boat strike damage. Private vessels 
Description of the Environment and Impact Analysis 4-109

participate in high-speed marine events concentrated in the southeastern U.S. and are a particular threat to 

sea turtles. The magnitude of the impacts resulting from such marine events is not currently known 

(USDOC, NMFS, 2002). Monofilament line was reported as the most common debris to entangle turtles 

(NRC, 1990). Fishing-related debris has been involved in about 68 percent of all cases of sea turtle 

entanglement (O’Hara and Iudicello, 1987).

A major source of mortality for loggerhead and Kemp’s ridleys is capture and drowning in shrimp 

trawls (Murphy and Hopkins-Murphy, 1989). Crowder et al. (1995) reported that 70-80 percent of turtle 

strandings were related to interactions with this fishery. Analysis of loggerhead strandings in South 

Carolina indicated a high turtle mortality rate from the shrimp fishery through an increase in strandings 

and that the use of turtle excluder devices could reduce strandings by 44 percent (Crowder et al., 1995). 

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. The NMFS has required the use of turtle excluder devices in southeast 

U.S. shrimp trawls since 1989. In response to increased numbers of dead sea turtles that washed up along 

the coasts of Texas, Louisiana, Georgia, and northeast Florida in 1994-1995, and coincident with coastal 

shrimp trawling activity, NMFS increased enforcement efforts (relative to turtle excluder devices), which 

decreased the number of strandings. After concerns arose that turtle excluder devices were not adequately 

protecting larger sea turtles, NMFS issued a Biological Opinion in 2002 that reported an estimated 

62,000 loggerhead and 2,300 leatherback sea turtles had been killed as a result of interaction with shrimp 

trawls. The Biological Opinion also stated that 75 percent of the loggerhead sea turtles in the GOM were 

too large to be protected by the turtle excluder devices. Subsequent regulation issued by NMFS in 2003 

required larger openings to better protect the larger sea turtles. The use of turtle excluder devices is 

believed to reduce hard-shelled sea turtle captures by 97 percent. Even so, NMFS estimated that 

4,100 turtles may be captured annually by shrimp trawling, including 650 leatherbacks that cannot be 

released through turtle excluder devices, 1,700 turtles taken in nets, and 1,750 turtles that fail to escape 

through the turtle excluder devices. Other fisheries and fishery-related activities are important sources of 

mortality but are collectively only one-tenth as important as shrimp trawling (NRC, 1990). Turtles may 

be accidentally caught and killed in finfish trawls, seines, gill nets, weirs, traps, longlines, and driftnets 

(Hillestad et al., 1982; NRC, 1990; Witzell, 1992; Brady and Boreman, 1994). Various fishing methods 

used in State fisheries, including trawling, pot fisheries, fly nets, and gillnets, are known to cause 

interactions with sea turtles. 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 Fisheries 

Council and is not federally regulated for sea turtle take. Condrey and Rester (1996) reported a hawksbill 

take in the fishery, and other takes have been reported in the fishery between 1992 and 1999 (De Silva, 

1998).

Coastal habitats such as algae and seagrass beds are frequented by sea turtles seeking food and shelter 

(Carr and Caldwell, 1956; Hendrickson, 1980). Submerged vegetated areas may be lost or damaged by 

activities altering salinity, turbidity, or natural tidal and sediment exchange. Natural catastrophes, 

including storms, floods, droughts, and hurricanes, can also substantially damage nesting beaches and 

coastal areas used by sea turtles (Agardy, 1990). 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-

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. The 

greatest surge effect from Hurricane Andrew in 1992 was experienced at beaches closest to the “eye” of 

the hurricane; egg mortality was 100 percent (Milton et al., 1994). In areas farther from the “eye,” the 

surge was lower and mortality was correspondingly decreased. Sixty-nine percent of eggs on Fisher 

Island in Miami, Florida, did not hatch after Hurricane Andrew and appeared to have “drowned” during 

the storm (Milton et al., 1994). Further mortality occurred when surviving turtles suffocated in nests 

situated in the beach zone where sand had accreted. This subsequent mortality may be reduced if beach 
4-110 Central Planning Area Lease Sales 235, 241, and 247 EIS

topography is returned to normal and beach debris is removed after a hurricane (Milton et al., 1994). 

Species that have limited nesting ranges, such as the Kemp’s ridley, would be greatly impacted if a 

hurricane made landfall at its nesting beach (Milton et al., 1994). Hurricane Erin in 1995 caused a 

40.2 percent loss in loggerhead hatchling production on the southern half of Hutchinson Island (Martin, 

1996). A beach can be completely unavailable to nesting after a hurricane. For example, at Buck Island 

Reef National Monument on St. Croix, after Hurricane Hugo in 1989, 90 percent of the shoreline trees on 

the North Shore were blown down parallel to the water, blocking access to nesting areas (Hillis, 1990). 

The number of false crawls (i.e., a nesting attempt) for hawksbill turtles increased significantly after the 

hurricane, mostly because of fallen trees and eroded root tangles blocking nesting attempts (Hillis, 1990). 

Other direct impacts of Hurricane Hugo on sea turtle habitats include the destruction of coral reef 

communities important to hawksbill and green turtles. Nooks and crannies in the reef used by these 

turtles for resting were destroyed in some areas (Agardy, 1990). Seagrass beds, which are important 

foraging areas for green turtles, were widely decimated in Puerto Rico (Agardy, 1990). Indirect effects 

(contamination of food or poisoning of reef-building communities) on the offshore and coastal habitats of 

sea turtles include pollution of nearshore waters from storm-associated runoff.

Summary and Conclusion

As described above, few deaths are expected from chance collisions with OCS oil- and gas-related

service vessels, ingestion of plastic material, commercial fishing, and pathogens. Disturbance (noise from 

vessel traffic and drilling operations) and/or exposure to sublethal levels of toxins and anthropogenic 

contaminants may stress animals, weaken their immune systems, and make them more vulnerable to 

parasites and diseases that normally would not be fatal during their life cycle. The net result of any 

disturbance depends upon the size and percentage of the population likely to be affected, the ecological 

importance of the disturbed area, the environmental and biological parameters that influence an animal’s 

sensitivity to disturbance and stress, or the accommodation time in response to prolonged disturbance 

(Geraci and St. Aubin, 1980). As discussed above, lease stipulations and regulations are in place to 

reduce vessel strike mortalities. As discussed in Appendix B, a low-probability catastrophic event could 

have population-level effects on sea turtles. 

The effects of a CPA proposed action, when viewed in light of the effects associated with other past, 

present, and reasonably foreseeable future activities, may result in greater impacts to sea turtles than 

before the Deepwater Horizon explosion, oil spill, and response; however, the magnitude of those effects 

cannot yet be determined. Nonetheless, operators are required to follow all applicable lease stipulations 

and regulations, as clarified by NTL’s, to minimize these potential interactions and impacts. The 

operator’s reaffirmed compliance with NTL 2012-JOINT-G01 (“Vessel Strike Avoidance and 

Injured/Dead Protected Species Reporting”) and NTL 2012-BSEE-G01 (“Marine Trash and Debris 

Awareness Elimination”), as well as the limited scope, timing, and geographic location of a CPA 

proposed action, would result in negligible effects from the proposed drilling activities on sea turtles. In 

addition, NTL 2012-JOINT-G02, “Implementation of Seismic Survey Mitigation Measures and Protected 

Species Observer Program,” minimizes the potential of harm from seismic operations to sea turtles and 

marine mammals; these mitigations include onboard observers, airgun shut-downs for whales in the 

exclusion zone, ramp-up procedures, and the use of a minimum sound source. Therefore, no significant 

cumulative impacts to sea turtles would be expected as a result of the proposed exploration activities 

when added to the impacts of past, present, or reasonably foreseeable oil and gas development in the area, 

as well as other ongoing activities in the area.

Adverse effects may result from the incremental contribution of a CPA proposed action combined 

with non-OCS oil- and gas-related activities. The biological significance of any mortality or adverse 

impact would depend, in part, on the size and reproductive rates of the affected populations, as well as the 

number, age, and size of animals affected. However, as the analyses above indicate, the potential for 

impacts is mainly focused on the individual, and population-level impacts are not anticipated based on the 

best available information.

Incremental injury effects from a CPA proposed action on sea turtles are expected to be negligible for 

drilling and vessel noise and minor for vessel collisions but will not rise to the level of significance

because of the limited scope, duration, and geographic area of the proposed drilling and vessel activities 

and the relevant regulatory requirements.
Description of the Environment and Impact Analysis 4-111

The effects of a CPA proposed action, when viewed in light of the effects associated with other 

relevant activities, may affect sea turtles occurring in the GOM. With the enforcement of regulatory 

requirements for drilling and vessel operations and the scope of a CPA proposed action, the incremental 

effects from the proposed drilling activities on sea turtles will be negligible (drilling and vessel noise) to 

minor (vessel strikes). The best available scientific information indicates that sea turtles do not rely on 

acoustics; therefore, vessel noise and related activities would have limited effect. Consequently, no 

significant cumulative impacts would be expected from a CPA proposed action’s activities or as the result 

of past, present, or reasonably foreseeable oil and gas leasing, exploration, development, and production 

in the GOM. Even taking into account additional effects resulting from non-OCS oil- and gas-related

activities, the potential for impacts from a CPA proposed action is mainly focused on the individual. 

Population-level impacts are not anticipated based on the best available information.

Within the CPA, there is a long-standing and well-developed OCS Program (more than 50 years); 

there are no data to suggest that activities from the preexisting OCS Program are significantly impacting 

sea turtle populations. Therefore, in light of the above analysis of a CPA proposed action and its impacts, 

the incremental effect of a CPA proposed action on sea turtle populations is not expected to be significant 

when compared with non-OCS oil- and gas-related activities.

Unavailable information on effects to sea turtles from the Deepwater Horizon explosion, oil spill, and 

response (and thus changes to the sea turtle baseline in the affected environment) makes an understanding 

of the cumulative effects less clear. Here, BOEM concludes that the unavailable information from these 

events may be relevant to foreseeable significant adverse impacts to sea turtles. Relevant data on the 

status of sea turtle populations after the Deepwater Horizon explosion, oil spill, and response and 

increased sea turtle GOM strandings may take years to acquire and analyze, and impacts from the 

Deepwater Horizon explosion, oil spill, and response may be difficult or impossible to discern from other 

factors. Therefore, it is not possible for BOEM to obtain this information within the timeline 

contemplated in the NEPA analysis of this Supplemental EIS, regardless of the cost or resources needed. 

In light of the incomplete or unavailable information, BOEM’s subject-matter experts have used available 

scientifically credible evidence in this analysis and based upon accepted scientific methods and 

approaches. Nevertheless, a complete understanding of the missing information is not essential to a 

reasoned choice among alternatives for this Supplemental EIS (including the No Action and Action 

Alternatives) for the two main reasons listed below:

(1) The CPA is an active oil and gas region with ongoing (or the potential for) 

exploration, drilling, and production activities. The potential for effects from 

changes to the affected environment (post-Deepwater Horizon explosion, oil spill, 

and response), routine activities, accidental spills (including low-probability 

catastrophic spills), and cumulative effects remains whether or not the No Action or 

an Action alternative is chosen under this Supplemental EIS. Impacts on sea turtles

from either smaller accidental events or low-probability catastrophic events will 

remain the same.

(2) All wide-ranging populations of sea turtles that may occur in the CPA and within 

areas affected by the spill are unlikely to have experienced population-level effects 

from the Deepwater Horizon explosion, oil spill, and response given their wideranging distribution and behaviors.

In any event, the incremental contribution of a CPA proposed action would not be likely to result in a 

significant incremental impact on sea turtles within the CPA; in comparison, non-OCS oil- and gasrelated activities such as overexploitation, commercial fishing, and pollution have historically proved to 

be of greater threat to the sea turtle species.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources (NOAA’s and FWS’s websites, and the RestoreTheGulf.gov 

website), as well as recently published journal articles was conducted to determine the availability of 

recent information on sea turtles. 
4-112 Central Planning Area Lease Sales 235, 241, and 247 EIS

The loggerhead sea turtle was listed as a threatened species on July 28, 1978 (Federal Register, 

1978). In 2011, NMFS and FWS listed nine distinct population segments (DPS) of loggerhead sea turtles

under the ESA (Federal Register, 2011b). Loggerheads found in the GOM are part of the Northwest 

Atlantic Ocean DPS. On March 25, 2013, the FWS published a proposed rule for the “Designation of 

Critical Habitat for the Northwest Atlantic Ocean Distinct Population Segment of the Loggerhead Sea 

Turtle (Caretta caretta)” (Federal Register, 2013c). On July 18, 2013, the NMFS published a proposed 

rule for the “Endangered and Threatened Species: Designation of Critical Habitat for the Northwest 

Atlantic Ocean Loggerhead Sea Turtle Distinct Population Segment (DPS) and Determination Regarding 

Critical Habitat for the North Pacific Ocean Loggerhead DPS” (Federal Register, 2013d).

To date for 2013, a notable increase in sea turtle strandings has occurred in the northern GOM as 

compared with 2012 stranding data. While turtle strandings in this region typically increase in the spring, 

the recent increase is a cause for concern. The Sea Turtle Stranding and Salvage Network is monitoring 

and investigating this increase. The network encompasses the coastal areas of the 18 states from Maine 

through Texas. There are many possible reasons for the increase in strandings in the northern GOM, both 

natural and human caused (USDOC, NMFS, 2013c). These sea turtle species include loggerhead, green, 

Kemp’s ridley, leatherback, hawksbill, and unidentified species. As of August 25, 2013, NMFS has 

identified 44 strandings in Alabama, 198 strandings in Louisiana, and 196 strandings in Mississippi.

Debris ingestion, particularly plastic debris, is an ongoing threat to marine turtles. A recent literature 

and data synthesis by Schuyler et al. (2013) found that smaller individuals in the oceanic life stage are 

more likely to ingest debris than are individuals foraging in coastal areas; likewise, species that feed 

primarily on plants or gelatinous zooplankton (“jellyfish”) are more likely to ingest debris than 

carnivorous species. In particular, oceanic green and leatherback turtles are at a higher risk for ingestion 

of pelagic floating plastics than benthic feeding carnivorous turtles. Increases in debris ingestion for 

leatherbacks in particular show an increasing trend until 1985, at which point the probabilities with 

ingestion leveled, suggesting that debris distribution may have stabilized and that the environment has 

reached a saturation point in which debris no longer reaches new areas but ends up in the same locations 

(Schuyler et al., 2013).

As of the conclusion of nesting season on August 31, 2013, 79 nests had been counted along the 

Alabama Gulf Coast (Share the Beach, 2013). In 2012, a total of 149 nests were counted along the 

Alabama Gulf Coast (Share the Beach, 2013). In 2011 and 2010, Alabama reported 84 and 41 sea turtle 

nests, respectively (Share the Beach, 2013). In Florida, the Northern Gulf of Mexico nesting loggerhead 

population declined by almost half between 1994 and 2010 (Lamont et al., 2012). Nesting surveys are not 

conducted in Mississippi or Louisiana due to logistical and funding limitations, although intermittent 

observations indicate that some nesting does occur (USDOI, FWS, 2013).

Postnesting Kemp’s ridley female sea turtles appear to have foraging hotspots in the northern Gulf of 

Mexico, particularly in waters off Louisiana (Shaver et al., 2013). Loggerheads have been observed using 

both neritic habitats and oceanic habitats to forage based on size; smaller sea turtles use oceanic habitats 

and larger sea turtles remain nearshore in coastal areas to forage following nesting (Eder et al., 2012). 

Nesting activities by the northern Gulf of Mexico subpopulation suggest that site fidelity is significantly 

less than originally estimated, with several individuals using geographically separate beaches in the same 

nesting season. Additionally, some loggerheads use large ranges during inter-nesting periods in relatively 

shallow water not necessarily adjacent to nesting beaches; these long distance movements overlap areas 

of trawling and OCS oil and gas activities. In particular, loggerheads use neritic habitats off of Florida 

and Alabama as movement corridors and inter-nesting sites (Hart et al., 2013). More analyses and an 

understanding of sea turtle foraging behavior and site selection in the northern GOM is needed.

Recent work on PAH’s (e.g., compounds found in crude oil, through combustion of fossil fuels, and 

urban runoff) suggests that PAH’s may not be bioaccumulated throughout their lifetime and likely are 

related to recent exposure to waters or food sources contaminated by PAH’s. High levels of PAH 

contaminants in smaller turtles may be related to their foraging strategies and suggest that, like other 

higher trophic organisms, sea turtles are able to metabolize PAH contaminants. Fluoranthene, in 

particular, was found at higher levels in sea turtles stranded following crude oil ingestion (Camacho et al., 

2012). Increased levels of total proteins, albumin, globulins, and creatinine correlated with persistent 

organic pollutants and PAH’s suggest that kidney function as well as other health parameters in sea turtles 

could be affected by exposure to these pollutants (Camacho et al., 2013).

Unavailable information on the effects to sea turtles from the Deepwater Horizon explosion, oil spill, 

and response (and thus changes to the sea turtle baseline in the affected environment), makes an 
Description of the Environment and Impact Analysis 4-113

understanding of the cumulative effects less clear. Here, BOEM concludes that the unavailable 

information from these events may be relevant to foreseeable significant adverse impacts to sea turtles. 

Relevant data on the status of sea turtle populations after the Deepwater Horizon explosion, oil spill, and 

response and increased sea turtle GOM strandings may take years to acquire and analyze, and impacts 

from the Deepwater Horizon explosion, oil spill, and response may be difficult or impossible to discern 

from other factors. Therefore, it is not possible for BOEM to obtain this information within the timeline 

contemplated in the NEPA analysis of this Supplemental EIS, regardless of the cost or resources needed. 

In light of the incomplete or unavailable information, BOEM’s subject-matter experts have used available 

scientifically credible evidence in this analysis based upon accepted scientific methods and approaches. 

Nevertheless, a complete understanding of the missing information is not essential to a reasoned choice 

among alternatives for this Supplemental EIS (including the No Action and Action alternatives) for the

two main reasons listed below:

(1) The CPA is an active oil and gas region with ongoing (or the potential for) 

exploration, drilling, and production activities. In addition, non-OCS oil- and gasrelated activities will continue to occur in the CPA irrespective of a CPA proposed 

action (i.e., fishing, military activities, scientific research, and shoreline 

development). The potential for effects from changes to the affected environment 

(post-Deepwater Horizon explosion, oil spill, and response), routine activities, 

accidental spills (including low-probability catastrophic spills), and cumulative 

effects remains whether or not the No Action or an Action alternative is chosen 

under this Supplemental EIS. Impacts on sea turtles from either smaller accidental 

events or low-probability catastrophic events will remain the same.

(2) All wide-ranging populations of sea turtles that may occur in the CPA and within 

areas affected by the spill are unlikely to have experienced population-level effects 

from the Deepwater Horizon explosion, oil spill, and response given their wideranging distribution and behaviors.

Nevertheless, there are existing leases in the CPA with either ongoing or the potential for exploration, 

drilling, and production activities. In addition, non-OCS oil- and gas-related activities discussed above

will continue to occur in the CPA irrespective of a CPA proposed action (i.e., fishing, military activities, 

and scientific research). The potential for effects from changes to the affected environment (postDeepwater Horizon explosion, oil spill, and response), routine activities, accidental spills (including lowprobability catastrophic spills), and cumulative effects remains whether or not the No Action or Action 

alternative is chosen under this Supplemental EIS.

4.1.1.14.Diamondback Terrapins

BOEM has reexamined the analysis for diamondback terrapins presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented below. No new significant information was discovered that would alter the impact conclusion 

for two species listed as vulnerable, the Mississippi diamondback terrapin (Malaclemys terrapin pileata) 

and the Texas diamondback terrapin (Malaclemys terrapin littoralis), presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The national and subnational 

conservation status ranks of Texas and Mississippi diamondback terrapins as vulnerable, at moderate risk 

of extirpation in the jurisdiction due to a fairly restricted range, relatively few populations or occurrences, 

recent and widespread declines, threats, or other factors. The analysis and potential impacts detailed in 

the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still 

apply for proposed CPA Lease Sales 235, 241, and 247.

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

CPA proposed action are presented in Chapter 4.2.1.14 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.14 of the WPA 233/CPA 231 Supplemental EIS. A 

CPA proposed action’s incremental contribution to the cumulative impacts is below. New information 

that has become available since those documents were published is presented below.
4-114 Central Planning Area Lease Sales 235, 241, and 247 EIS

A detailed description of both the Mississippi and the Texas diamondback terrapins can be found in 

Chapter 4.2.1.14.1 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.14 of the WPA 233/CPA 231 Supplemental EIS.

Impacts of Routine and Accidental Events

The following routine activities associated with proposed CPA Lease Sales 235, 241, and 247 would 

potentially affect diamondback terrapins: beach trash and debris generated by service vessels and OCS 

facilities; efforts undertaken for the removal of marine debris or for beach restoration; and vessel traffic 

(boat propeller strikes or groundings) with associated habitat (coastal marsh) erosion. A detailed impact 

analysis of the routine impacts of proposed CPA Lease Sales 235, 241, and 247 on diamondback terrapins 

can be found in Chapter 4.2.1.14.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information 

is provided in Chapter 4.2.1.14 of the WPA 233/CPA 231 Supplemental EIS.

Adverse impacts due to routine activities resulting from the CPA proposed action are possible but 

unlikely. Because of the greatly improved handling of waste and trash by industry and because of the 

annual awareness training required by the marine debris mitigations, the plastics in the ocean are 

decreasing and the devastating effects on offshore and coastal marine life are minimizing. The routine 

activities of a CPA proposed action are unlikely to have significant adverse effects on the size and 

recovery of any terrapin species or population in the GOM. Most routine, OCS oil- and gas-related

activities are expected to have sublethal effects, such as behavioral effects, that are not expected to rise to 

the level of population significance.

Impact-producing factors associated with accidental events that may be associated with a CPA 

proposed action that could affect diamondback terrapins include offshore and coastal oil spills and spillresponse activities. A detailed impact analysis of the accidental impacts that may be associated with 

proposed CPA Lease Sale 235 on diamondback terrapins can be found in Chapter 4.2.1.14.3 of the 2012-

2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.14 of the WPA 

233/CPA 231 Supplemental EIS.

Impacts on Mississippi and Texas diamondback terrapins from smaller accidental events are likely to 

affect individual diamondback terrapins in the spill area, but they are unlikely to rise to the level of 

population effects (or a level of significance) given the probable size and scope of such spills. Further, 

the potential remains for smaller accidental spills to occur in the CPA proposed action area, regardless of 

any alternative selected under this Supplemental EIS, given that it is an active oil and gas region with 

either ongoing or the potential for exploration, drilling, and production activities.

The analyses in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS 

conclude that there is a low probability for catastrophic spills. Appendix B of this Supplemental EIS also 

concludes that there is a potential for a low-probability catastrophic event, though not reasonably 

foreseeable and not part of a CPA proposed action, to result in significant, population-level effects on 

affected diamondback terrapin species. BOEM continues to concur with the conclusions from these 

analyses.

Malaclemys terrapin are federally listed as a species of concern. “Species of concern” is an informal 

term that refers to those species that might be in need of concentrated conservation actions. Such 

conservation actions vary depending on the health of the populations and degree and types of threats. At 

one extreme, there may only need to be periodic monitoring of populations and threats to the species and 

its habitat. At the other extreme, a species may need to be listed as a federally threatened or endangered 

species under the ESA. Species of concern receive no legal protection above those already afforded the 

species under other laws, and the use of the term does not necessarily mean that the species will 

eventually be proposed for listing as a threatened or endangered species. At the present time, the 

diamondback terrapin is neither a listed species nor a candidate for listing under the ESA.

Summary and Conclusion

The effects of a CPA proposed action, when viewed in light of the effects associated with other past, 

present, and reasonably foreseeable future activities may result in greater impacts to diamondback 

terrapins than before the Deepwater Horizon explosion, oil spill, and response; however, the magnitude of 

those effects cannot yet be determined. Nonetheless, to mitigate potential impacts from OCS oil- and gasrelated activities, operators are required to follow all applicable lease stipulations and regulations, as 
Description of the Environment and Impact Analysis 4-115

clarified by NTL’s, to minimize these potential interactions and impacts. The operator’s reaffirmed 

compliance with NTL 2012-BSEE-G01 (“Marine Trash and Debris Awareness and Elimination”), as well 

as the limited scope, timing, and geographic location of a CPA proposed action, would result in negligible 

effects from the proposed drilling activities on diamondback terrapins.

A complete understanding of the missing information is not essential to establish a reasoned choice 

among alternatives for this Supplemental EIS (including the No Action and Action alternatives). The 

potential for diamondback terrapins to be affected from changes to the affected environment (postDeepwater Horizon explosion, oil spill, and response), routine activities, accidental spills (including lowprobability catastrophic spills), and cumulative effects will remain regardless of whether or not the No 

Action an Action alternative is chosen under this Supplemental EIS. The rate of current and historic loss 

of terrapin habitat in Louisiana, for example, far exceeds the potential impacts to terrapin habitat from the 

Deepwater Horizon explosion, oil spill, and response. 

BOEM has reexamined the analysis for diamondback terrapins presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented above. No new significant information was discovered that would alter the impact conclusion 

for diamondback terrapins presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS because of the available scientifically credible evidence in this analysis and based upon 

accepted scientific methods and approaches. The analysis and potential impacts detailed in the 2012-

2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

The major impact-producing factors that may affect the Texas diamondback terrapin (Malaclemys 

terrapin littoralis) and the Mississippi diamondback terrapin (Malaclemys terrapin pileata) include oil 

spills and spill-response activities, alteration and reduction of habitat, and consumption of trash and 

debris.

OCS Oil- and Gas-Related Activities

The incremental contribution of a CPA proposed action to cumulative impacts on both the Texas and 

the Mississippi diamondback terrapins would be expected to be minimal. The major OCS oil- and gasrelated, impact-producing factors that may affect the diamondback terrapin include (1) habitat destruction, 

(2) vessel traffic and road mortality, (3) exposure or intake of OCS oil- and gas-related contaminates or 

debris, and (4) oil spills and spill response.

Spending most of their lives within their limited home ranges at the aquatic-terrestrial boundary in 

estuaries, terrapins are susceptible to OCS oil- and gas-related habitat destruction (i.e., infrastructure

construction, direct oil contact and associated cleanup efforts). Habitat loss has the potential to increase 

terrapin vulnerability to predation and increase competition. Pipelines from offshore oil and gas and other 

shoreline crossings have contributed to marsh erosion. However, a CPA proposed action would include 

only limited shoreline crossings and modern regulations requiring mitigation of wetland impacts. For 

additional effects of OCS oil- and gas-related habitat loss in beaches and dunes and in wetlands, refer to 

Chapters 4.2.1.3 and 4.2.1.4 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. Refer to Chapter 4.2.1.23.1 of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS for infrastructure-related habitat loss.

Vessel traffic and road mortality has the potential to affect diamondback terrapin populations. 

Terrapin populations are susceptible to propeller strikes by vessels traveling through wetland or beach 

habitat, and injury from strikes can cause mortality (Roosenburg, 1991). There have been no documented 

terrapin collisions with drilling and service vessels in the GOM. However, recreational vessel strikes in 

shallower waters of estuarine environments, where terrapins are most often found, is documented and 

suggests that there may be impacts associated with vessel traffic from OCS oil- and gas-related activities 

that require movement through estuarine habitat (Lester et al., 2012; Cecala et al., 2008). Vehicular 

traffic servicing ports or service bases located adjacent to terrapin habitat can lead to terrapin mortality, 

specifically during nesting season when gravid females emerge to lay their eggs (Szerlag and McRobert, 

2006).
4-116 Central Planning Area Lease Sales 235, 241, and 247 EIS

Behavioral effects and nonfatal exposure to or intake of OCS oil- and gas-related contaminants or 

discarded debris may stress and/or weaken individuals of a local group or population and predispose them 

to infection from natural or anthropogenic sources. Greatly improved handling of waste and trash by 

industry, along with the annual awareness training required by the marine debris mitigations, is 

decreasing the plastics in the ocean and minimizing the devastating effects on wildlife. The incidental 

ingestion of marine debris and entanglement could adversely affect terrapins. This Agency has 

established the guidance provided in NTL 2012-BSEE-G01, “Marine Trash and Debris Awareness and 

Elimination,” which appreciably reduces the likelihood of terrapin encountering marine debris from a 

CPA proposed action. A CPA proposed action is expected to contribute negligible marine debris or 

disruption to terrapin habitat. Unless properly regulated, removing marine debris may temporarily disturb 

terrapins or trample nesting sites. Due to the extended distance from shore, most activities associated 

with the OCS Program are not expected to impact terrapins or their habitat.

Most spills related to a CPA proposed action, as well as oil spills stemming from tankering and prior 

and future lease sales, are not expected to contact terrapins or their habitats. Even after the oil is no 

longer visible, terrapins may still be exposed while they forage in the salt marshes lining the edges of 

estuaries where oil may have accumulated under the sediments and within the food chain (Burger, 1994; 

Roosenburg et al., 1999; Holliday et al., 2008). Oil spills that affect beaches and dunes could potentially 

reduce terrapin nest size and lead to reduced hatchability (Wood and Hales, 2001). Nests can also be 

disturbed or destroyed by cleanup efforts. In addition, terrapins rarely move from one tidal creek to 

another (Gibbons et. al, 2001). Even if an oil spill is contained to one area, localized extirpation may 

occur in a subpopulation; however, total population-level effects would not be expected. Refer to 

Chapters 4.1.1.3 and 4.1.1.4 of this Supplemental EIS and Chapters 4.2.1.3 and 4.2.1.4 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS for additional effects OCS oil- and 

gas-related activity to habitat loss in beaches and dunes and in wetlands. 

Data collected by the Operational Science Advisory Team indicate that the Deepwater Horizon

explosion, oil spill, and response may have impacted the beach and brackish habitats associated with 

terrapin communities (OSAT, 2010). For those terrapin populations that may not have been impacted by 

the Deepwater Horizon explosion, oil spill, and response, it is unlikely that a future accidental event 

related to the CPA proposed action would result in significant impacts due to distance of most of the 

terrapin habitat from offshore OCS oil- and gas-related activities. As discussed in Appendix B, a lowprobability catastrophic event could have population-level effects on diamondback terrapins. The best 

available information does not provide a complete understanding of the effects of the spilled oil and 

active response/cleanup activities related to the Deepwater Horizon explosion, oil spill, and response on 

the potentially affected terrapin environment. 

Unavailable information on the effects to diamondback terrapins from the Deepwater Horizon

explosion, oil spill, and response (and thus changes to the diamondback terrapin baseline in the affected 

environment) makes an understanding of the cumulative effects less clear. Here, BOEM concludes that 

the unavailable information from these events may be relevant to foreseeable significant adverse impacts 

to diamondback terrapins. Relevant data on the status of diamondback terrapin populations after the 

Deepwater Horizon explosion, oil spill, and response may take years to acquire and analyze, and impacts 

may be difficult or impossible to discern from other factors. Therefore, it is not possible for BOEM to 

obtain this information within the timeline contemplated in the NEPA analysis of this Supplemental EIS, 

regardless of the cost or resources needed. In light of the incomplete or unavailable information, 

BOEM’s subject-matter experts have used available scientifically credible evidence in this analysis and 

based upon accepted scientific methods and approaches.

Nevertheless, a complete understanding of the missing information is not essential to a reasoned 

choice among alternatives for this Supplemental EIS (including the No Action and Action alternatives). 

The CPA is an active oil and gas region with ongoing (or the potential for) exploration, drilling and 

production activities. The potential for effects from changes to the affected environment (post-Deepwater

Horizon explosion, oil spill, and response), routine activities, accidental spills (including low-probability 

catastrophic spills), and cumulative effects remains whether or not the No Action or an Action alternative 

is chosen under this Supplemental EIS. Impacts on diamondback terrapins from either smaller accidental 

events or low-probability catastrophic events will remain the same.
Description of the Environment and Impact Analysis 4-117

Non-OCS Oil- and Gas-Related Activities

Activities posing the greatest potential harm to terrapins are non-OCS oil- and gas-related factors, 

including (1) habitat destruction, (2) overharvesting and crab pot fishing, (3) vessel traffic and road 

mortality, (4) nest depredation, (5) State oil- and gas-related activity, and (6) natural processes.

Terrapin populations are susceptible to non-OCS oil- and gas-related habitat destruction (i.e., urban 

development, subsidence/sea-level rise, coastal land uses, coastal restoration program, and maintenance 

dredging), and road construction. Wave action from non-OCS oil- and gas-related vessel traffic can cause 

the erosion of important hibernating or nesting habitat. The development of waterfront property 

continues to reduce shoreline habitats available as habitat to terrapins. In addition, the use of stabilization 

fences on dunes near developed areas can impact the accessibility of nesting sites. For additional effects 

of non-OCS oil- and gas-related habitat loss in beaches and dunes and in wetlands, refer to Chapters 

4.1.1.3 and 4.1.1.4 of this Supplemental EIS and Chapters 4.2.1.3 and 4.2.1.4 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

Historically, the terrapin population suffered an initial decline due to overharvesting in the 1800’s 

(Hogan, 2003). As the development of shoreline areas increased, there has been an increase in 

recreational and commercial crab fisheries. Terrapins are known to become entrapped in crab pots, 

especially young females and males. Long-term crab pot use has been suggested to influence the 

demographics of terrapin populations (Dorcas et al., 2007). While terrapin excluder devices have been 

developed, not all states require their use. Roosenburg et al. (1997) estimated that up to 78 percent of a 

terrapin subpopulation can die annually as a result of crab pot fishing.

Vessel traffic and road mortality has the potential to affect diamondback terrapin populations. 

Terrapin populations are susceptible to propeller strikes by vessels traveling through wetland or beach 

habitat, and injury from strikes can cause mortality (Roosenburg, 1991). Recent studies on behavioral 

responses of diamondback terrapin to recreational boat sounds suggest that terrapins are sensitive to boat 

frequencies but do not appear to respond behaviorally to the anthropogenic boat sounds (Lester et al., 

2012). This failure to respond to boat sounds may be limiting populations in areas with heightened boat 

traffic. Major shell injuries and limb loss, many of which are attributed to boat propeller impact, has been 

shown to significantly reduce survivorship and reproductive output (Cecala et al., 2008).

Non-OCS oil- and gas-related traffic on roadways (e.g., to/from recreation or tourism areas) adjacent 

to terrapin habitat can lead to terrapin mortality, specifically during nesting season when gravid females 

emerge to lay their eggs (Szerlag and McRobert, 2006). Studies suggest that terrapin are attracted to the 

roadside because it meets the requirements for suitable nesting habitat (Szerlag and McRobert, 2006).

Characteristics of terrapin life history render this species especially vulnerable. These characteristics 

include low reproductive rates, low survivorship, limited population movements, and nest site fidelity 

year after year. In addition, non-OCS development can introduce predators to terrapin habitat by 

increasing the accessibility of the site (via road construction or other anthropogenic source). Raccoons 

alone can depredate more than 90 percent of nests of a single population (Feinberg and Burke, 2003).

State oil- and gas-related activities would affect terrapin populations in similar ways to OCS oil- and 

gas-related activities. Spills that occur as a result of State activity are generally closer to shore and are 

more likely to affect terrapin habitat. Non-OCS oil- and gas-related contamination and debris are 

expected to affect terrapins in a similar manner to OCS oil- and gas-related contamination and debris. For 

additional effects of non-OCS oil- and gas-related activities in beaches and dunes and in wetlands, refer to 

Chapters 4.1.1.3 and 4.1.1.4 of this Supplemental EIS and Chapters 4.2.1.3 and 4.2.1.4 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

Natural processes (i.e., coastal erosion) and natural catastrophes (i.e., hurricanes and tropical storms), 

in combination, could potentially deplete some terrapin populations to unsustainable levels. Beach 

erosion from tropical storms and hurricanes could threaten their preferred nesting habitats.

Summary and Conclusion 

Texas and Mississippi diamondback terrapins have experienced impacting pressures from habitat 

destruction, road construction, drowning in crab traps, and past overharvesting resulting in historical 

reductions in their habitat range and declines in populations. Inshore oil spills from non-OCS oil- and 

gas-related sources are potential threats to terrapins in their brackish coastal marshes. Pipelines from 

offshore oil and gas and other shoreline crossings have contributed to marsh erosion. However, a CPA 
4-118 Central Planning Area Lease Sales 235, 241, and 247 EIS

proposed action includes only limited shoreline crossings, and modern regulations require mitigation of 

wetland impacts. Low-probability catastrophic offshore oil spills could affect the coastal marsh 

environment but such events are rare occurrences and may not reach the shore, even if they do occur. 

Therefore, the incremental contribution of a CPA proposed action is expected to be minimal, compared 

with non-OCS oil- and gas-related activities. The major impact-producing factors resulting from the 

cumulative activities associated with a CPA proposed action that may affect the diamondback terrapin 

include oil spills and spill-response activities, alteration and reduction of habitat, and consumption of 

trash and debris. Due to the extended distance from shore, impacts associated with activities occurring on 

the OCS are not expected to impact terrapins or their habitat. No substantial information was found at 

this time that would alter the overall conclusion that cumulative impacts on diamondback terrapins 

associated with a CPA proposed action would be expected to be minimal.

BOEM has considered this assessment and has reexamined the cumulative analysis for diamondback 

terrapins and the cited new information. Based on this evaluation, the conclusions in these analyses on 

effects to diamondback terrapins remain unchanged in regards to routine activities (no potential for 

significant adverse effects) and accidental spills (potential for significant adverse effects).

Overall, within the CPA, there is a long-standing and well-developed OCS Program (more than 

50 years); there are no data to suggest that activities from the preexisting OCS Program are significantly 

impacting diamondback terrapin populations. Non-OCS oil- and gas-related activities will continue to 

occur in the CPA irrespective of a proposed CPA lease sale (i.e., crabbing, fishing, military activities, 

scientific research, and shoreline development). Therefore, in light of the above analysis of a CPA 

proposed action and its impacts, the incremental effect of a CPA proposed action on diamondback 

terrapins populations is not expected to be significant when compared with historic and current non-OCS 

oil- and gas-related activities, such as habitat loss, overharvesting, crabbing, and fishing.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources (NOAA’s and FWS’s websites, and the RestoreTheGulf.gov 

website), as well as recently published journal articles was conducted to determine the availability of 

recent information on diamondback terrapins. The search revealed little new information pertinent to this 

Supplemental EIS.

Non-OCS impacts from boat injuries are prevalent in terrapins and may be detrimental to populations 

but has had limited research conducted on its impacts. Recent studies on behavioral responses of 

diamondback terrapins to recreational boat sounds suggest that terrapins are sensitive to boat frequencies 

but do not appear to respond behaviorally to the anthropogenic boat sounds (Lester et al., 2012). This 

failure to respond to boat sounds may be limiting populations in high boating traffic areas. Major shell 

injuries and limb loss, many of which are attributed to boat impact, have been shown to significantly 

reduce survivorship and reproductive output (Cecala et al., 2008).

Diamondback terrapins within the CPA may have been impacted by the Deepwater Horizon

explosion, oil spill, and response, based on the best available information and the CPA’s distance from 

the Macondo well. The best available information on impacts to diamondback terrapins and their habitat 

does not yet provide a complete understanding of the effects of the oil spilled and active response/cleanup 

activities from the Deepwater Horizon explosion, oil spill, and response. As identified in the resource 

analyses in this Supplemental EIS, 2012-2017 WPA/CPA Multisale EIS, and WPA 233/CPA 231 

Supplemental EIS, incomplete or unavailable information regarding diamondback terrapins in the CPA 

may be relevant to reasonably foreseeable significant adverse effects. As data continue to be gathered 

and impact assessments completed, a better characterization of the full scope of the impacts to the terrapin 

populations in the GOM from the Deepwater Horizon explosion, oil spill, and response will be available. 

Relevant data on the status of diamondback terrapin populations after the Deepwater Horizon explosion, 

oil spill, and response may take years to acquire and analyze, and impacts may be difficult or impossible 

to discern from other factors. Therefore, it is not possible for BOEM to obtain this information within the 

timeline contemplated in the NEPA analysis of this Supplemental EIS, regardless of the cost or resources 

needed. In light of the incomplete or unavailable information, BOEM’s subject-matter experts have used 

available scientifically credible evidence in this analysis and applied it using accepted scientific methods 

and approaches. BOEM has determined that the information is not essential to a reasoned choice among 

alternatives.
Description of the Environment and Impact Analysis 4-119

4.1.1.15.Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice

BOEM has reexamined the analysis for Alabama, Choctawhatchee, St. Andrew, and Perdido Key 

beach mice (hereafter “beach mice”) presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS, based on the additional information presented below. No new 

significant information was discovered that would alter the impact conclusion for beach mice presented in 

the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The analysis and 

potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 

231 Supplemental EIS still apply for proposed CPA Lease Sale 235, 241, and 247.

A detailed description of the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice

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

CPA proposed action are presented in Chapter 4.2.1.15 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s 

incremental contribution to the cumulative impacts is presented below. Any new information that has 

become available since those documents were published is presented below.

Impacts of Routine and Accidental Events

The major impact-producing factors associated with routine activities of a CPA proposed action that 

may affect beach mice include beach trash and debris, and efforts undertaken for the removal of marine 

debris or for beach restoration. A detailed impact analysis of the routine impacts of OCS activities 

associated with proposed CPA Lease Sales 235, 241, and 247 on beach mice can be found in Chapter 

4.2.1.15.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 

4.2.1.15 of the WPA 233/CPA 231 Supplemental EIS.

Impacts from the routine activities associated with a CPA proposed action on beach mice are possible 

but unlikely. Impacts may result from consumption of or entanglement in beach trash and debris. It is 

expected that debris from a CPA proposed action would account for a small portion of the total debris that 

would reach beach mice habitat; thus, the impacts from a CPA proposed action would be minimal. The 

BSEE prohibits the disposal of equipment, containers, and other materials into offshore waters by lessees 

(30 CFR § 250.300; also refer to NTL 2012-BSEE-G01 “Marine Trash and Debris Awareness and 

Elimination”). In addition, MARPOL, Annex V, Public Law 100-220 (101 Statute 1458) prohibits the 

disposal of any plastics at sea or in coastal waters. Unless all personnel are adequately trained, efforts 

undertaken for the removal of marine debris may temporarily scare away beach mice or destroy their food 

resources, such as sea oats. However, their burrows have a plugged escape tunnel that would become 

functional if the main entrance was trampled. Sea oats are a protected species at the State and local level 

throughout all beach mice habitat, theoretically reducing the potential for destruction (refer to City of 

Gulf Shores Ordinance No. 2012-1141, ADEM Administrative Code Regulations 335-8-2-.08, and 

Florida Statute Title XI 161.242).

The major impact-producing factors resulting from accidental events associated with a CPA proposed 

action that may affect beach mice include offshore and coastal oil spills, and spill-response activities. A 

detailed impact analysis of the accidental impacts that may be associated with proposed CPA Lease Sales 

235, 241, and 247 on beach mice can be found in Chapter 4.2.1.15.3 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.15 of the WPA 233/CPA 231 

Supplemental EIS.

The oiling of beach mice or beach mice critical habitat could result in local extinction. Oil-spillresponse and cleanup activities could also have a substantial impact to the beach mice and their habitat if 

all cleanup personnel are not adequately trained. However, potential spills that could result from a CPA 

proposed action are not expected to wash onto or over the foredunes of beach mouse habitat (refer to 

Appendix B of this Supplemental EIS and Figure 3-11 of the 2012-2017 WPA/CPA Multisale EIS). 

Also, inshore facilities related to a CPA proposed action are unlikely to be located on beach mouse 

habitat.

Within the last 20-30 years, the combination of habitat loss due to beachfront development, the 

isolation of remaining beach mouse habitat areas and populations, and the destruction of remaining 

habitat by tropical storms and hurricanes has increased the threat of extinction of several subspecies of 

beach mice. Destruction of the remaining habitat, including critical habitat, due to a low-probability 
4-120 Central Planning Area Lease Sales 235, 241, and 247 EIS

catastrophic spill and cleanup activities would increase the threat of extinction, but the potential for a 

catastrophic spill that would substantially affect beach mice habitat is low.

A review of the available information shows that impacts on beach mice from accidental impacts 

associated with a CPA proposed action would be minimal.

Summary and Conclusion

New information does not indicate a change in the conclusions identified in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. An impact from the routine 

activities associated with a CPA proposed action on Alabama, Choctawhatchee, St. Andrew, and Perdido 

Key beach mice is possible but unlikely. Impacts on beach mice from accidental impacts that may be 

associated with a CPA proposed action would also be minimal. The expected incremental contribution of 

a CPA proposed action to the cumulative impacts remains small.

No new significant information was discovered that would alter the impact conclusion for the beach 

mice presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. 

The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in th 

WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

This cumulative analysis considers the possible cumulative effects of all activities in the CPA on the 

Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice, which are protected species under 

the ESA, and the Santa Rosa beach mouse (located in the same area but not listed under the ESA). Also 

included in this analysis are the federally threatened southeastern beach mouse and the federally 

endangered Anastasia Island beach mouse on the east coast of Florida, which are discussed because they 

could be exposed to an oil spill in the CPA if it was entrained in the Loop Current and was carried to their 

locations.

The major impact-producing factors that affect beach mice include OCS oil- and gas-related 

impacting factors such as oil spills (offshore and coastal) and associated cleanup operations, consumption 

of and entanglement in beach trash and debris, and non-OCS oil- and gas-related impacting factors such 

as beach development and alteration and reduction of habitat, predation (especially from domestic cats), 

competition, and natural catastrophes (i.e., hurricanes and tropical storms).

OCS Oil- and Gas-Related Impacts 

The OCS oil- and gas-related beach trash and debris and associated removal efforts may impact beach 

mice. The beach mice may consume the trash and debris, and they may become entangled in the debris. 

If a burrow is trampled by foot traffic of insufficiently trained debris cleanup personnel, it is likely beach 

mice could dig themselves out. However, they would be subject to additional energetic expenditure 

associated with rebuilding the burrow.

Most proposed action-related spills, as well as oil spills stemming from prior and future lease sales, 

are not expected to contact beach mice or their habitats, and no major impacts from associated cleanup 

operations are expected. If personnel are properly trained (on short notice if under emergency conditions) 

and supervised, these impacts could be reduced. Cumulative impacts could potentially deplete some 

beach mice populations to unsustainable levels. However, the expected incremental contribution of a 

CPA proposed action to the cumulative impacts is negligible.

Due to the extended distance of most OCS activities from shore, the incremental impacts associated 

with a CPA proposed action are not expected to impact beach mice when compared with the cumulative 

effects of non-OCS oil- and gas-related factors nearer to shore.

Non-OCS Oil- and Gas-Related Impacts

Substantial habitat loss due to sea-level rise is not expected to seriously affect beach mice habitat. 

The eastern Gulf of Mexico (Alabama and Florida) is underlain by a stable carbonate platform 

(limestone) that is not subject to subsidence to any substantial degree, and so it is predominantly 
Description of the Environment and Impact Analysis 4-121

influenced by absolute sea-level rise. A tidal gauge at Pensacola, Florida, showed an average relative sealevel rise of 2.1 mm/year. Absolute long-term, sea-level rise is expected to result in landward movement 

of beach and dune habitat, but the total habitat area may not necessarily decline from this sea-level rise 

alone.

Non-OCS oil- and gas-related beach trash and debris and associated removal efforts may impact 

beach mice. The beach mice may consume trash and debris, and they may become entangled in the 

debris. If a burrow is trampled by foot traffic of insufficiently trained debris cleanup personnel, beach 

mice could dig themselves out. However, they would be subject to additional energetic expenditure 

associated with rebuilding the burrow.

Predation by domestic cats is a serious threat to many native rodent species. According to the most 

up-to-date reference on the subject (Cascades Raptor Center, 2013), the only two available sources of 

reliable data on outdoor cats and beach mouse populations are 20-32 years old and indicate that “...cats 

introduced by people living on the barrier islands of Florida’s coast have depleted several unique species 

of mice and woodrats to near extinction.” More generally, domestic cats are an invasive species and have 

impacts on wildlife that feral cats and natural predators do not. Cats in general have more impact on 

wildlife than do natural predators. Competition between the hispid cotton rat (Sigmodon hispidus) and 

Alabama beach mouse may increase after a hurricane if the beach mouse is forced into a smaller habitat 

area (interior dune refuges) by hurricane damage to foredune habitat (Falcy, 2011; Yuro, 2011). The 

effects of oil spills from State oil- and gas-related activity and import tankering are expected to be similar 

to those of OCS oil- and gas-related impacts, and they are not expected to contact beach mice or their 

habitats. If personnel are properly trained (on short notice if under emergency conditions) and 

supervised, these impacts could be reduced.

Population viability analysis (PVA) is a demographic modeling exercise to predict the likelihood a 

population will continue to persist over time given the influence of stochastic (i.e., unpredictable) events 

(Groom and Pascual, 1998). The PVA models have potential problems with usefulness to managers 

because they are untested and complex (Hanski, 1999). The objective of a PVA for beach mice is to 

determine how large and what configuration of habitat is necessary to reasonably assure that the species 

will survive to recover. In the first version of a PVA model of the Alabama beach mouse, many of the 

model parameters were uncertain and may have been inaccurate, resulting in uncertainty in the probability 

of Alabama beach mouse extinction (Traylor-Holzer et al., 2005). The model was revised after Hurricane

Ivan (Traylor-Holzer, 2005) and then data collected after Hurricane Katrina were used in a second 

revision of the model (Reed and Traylor-Holzer, 2006). The most recent revised model projects a risk of 

extinction of 26.8 ± 1.0 percent over the next 100 years. Destruction of migration corridors between 

populations raises the risk to 41.2 ± 1.1 percent, but only 34.9 ± 1.1 percent with the translocation of 

mice. Total loss of private land as suitable habitat raises the risk further to 46.8 ± 1.1 percent, but only

40.8 ± 1.1 percent with the translocation of mice.

Falcy (2011) used modelling to show smooth recovery of Alabama beach mouse populations during 

the 4 years after Hurricane Ivan (2004) and Hurricane Katrina (2005). Further modelling (Falcy, 2011) 

showed that increasing the rate of population growth in a refuge, like interior dunes after a hurricane, 

would have a much larger effect on population persistence than increasing the rate of recovery of 

damaged habitat, like foredunes after a hurricane. Occupancy of frontal dunes by Santa Rosa beach mice

dropped from 100 percent to 40 percent after Hurricane Ivan, but occupancy of interior (scrub) dunes at 

75 percent did not change (Pries et al., 2009). 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. 

Hurricanes cause increased fragmentation of habitat, which is correlated with increased distance (gap 

width) between fragments that must be crossed by beach mice at night if they are to move between habitat 

patches. Beach mice, which are nocturnal, may prefer to cross narrower gaps to avoid exposure to 

predators (Wilkinson et al., 2013). The frequency of gap crossing may decrease when visibility is good 

during the full moon when mice are more visible to predators, as compared with the frequency during the 

new moon (Wilkinson et al., 2013). Within the historic ranges of the four Gulf Coast beach mouse 

subspecies, between 1851 and 2006, 58 hurricanes have made landfall in northwest Florida and 

21 hurricanes have made landfall in Alabama (McAdie et al., 2009; USDOC, NOAA, National Hurricane 

Center, 2012). This high historic and contemporary frequency of extreme disturbance has been a form of 

natural selection to which the beach mice were adapted until it was combined with anthropogenic habitat 

loss and fragmentation.
4-122 Central Planning Area Lease Sales 235, 241, and 247 EIS

Summary and Conclusion

New information does not indicate a change in the conclusions identified in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/ CPA 231 Supplemental EIS. Cumulative activities have the 

potential to harm or reduce the numbers of Alabama, Choctawhatchee, St. Andrew, and Perdido Key 

beach mice. Those activities include oil spills, alteration and reduction of habitat, predation and 

competition, consumption of and entanglement in beach trash and debris, beach development, and natural 

catastrophes (hurricanes and tropical storms). Most spills related to a CPA proposed action and prior and 

future lease sales are not expected to contact beach mice or their habitats because the species lives above 

the mean high waterline where contact is less likely. Cumulative impacts could potentially deplete some 

beach mice populations to unsustainable levels, but non-OCS oil- and gas-related drivers are expected to 

have a greater impact than OCS activities. The expected incremental contribution of a CPA proposed 

action to the cumulative impacts is negligible.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search for new information available since the publication of the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS identified several new publications, but none were 

pertinent to OCS oil- and gas-related activities and their effects. Searches were made using EBSCO, 

ScienceDirect, Google Advanced Scholar Search, and Google Advanced Book Search using the keywords 

“beach mouse,” “dunes,” and “Peromyscus polionotus.” The Internet was searched for any new 

information, and a local FWS beach mouse expert was contacted (Frater, official communication, 2013). 

Updated information on hurricane frequencies that affected beach mice habitats was identified and 

incorporated into the cumulative impact analysis above.

BOEM acknowledges that there remains incomplete or unavailable information regarding beach 

mice, including information regarding the Deepwater Horizon explosion, oil spill, and cleanup and 

impacts from that spill to beach mice. Nevertheless, there is scientifically credible information regarding 

the likelihood that beach mice were minimally impacted by oil and related tarballs from the Deepwater 

Horizon explosion. Current studies are investigating the effects of Deepwater Horizon explosion, oil 

spill, and response activities on beach mice and their habitat (Frater, official communication, 2013). This 

research is being conducted through the NRDA process and may be years from completion. These data 

and conclusions are currently under litigation and are unavailable. 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 of this Supplemental EIS. In its place, BOEM has included what 

scientifically credible information is available and applied it using accepted scientific methodologies. 

Although information resulting from this study may be relevant to reasonably foreseeable adverse impacts 

on beach mice and their habitat, BOEM’s subject-matter experts have determined that it is not essential to 

a reasoned choice among the alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS. BOEM has conservatively considered the 

potential for impacts from cleanup activities.

4.1.1.16.Coastal and Marine Birds

BOEM has reexamined the analysis for coastal and marine birds presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS based on the additional information 

presented below. No new significant information was discovered that would alter the impact conclusion 

for coastal and marine birds presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 

231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA 

Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA 

Lease Sales 235, 241, and 247.

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

CPA proposed action are presented in Chapter 4.2.1.16 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s 

incremental contribution to the cumulative impacts is presented below. The following information is a 

summary of the resource description incorporated from the 2012-2017 WPA/CPA Multisale EIS and 
Description of the Environment and Impact Analysis 4-123

WPA 233/CPA 231 Supplemental EIS. Any new information that has become available since those 

documents were published is presented below.

Impacts of Routine and Accidental Events

The majority of the effects resulting from routine activities of a CPA proposed action (Tables 3-2 

through 3-4) on threatened or endangered (Table 4-1 of the WPA 233/CPA 231 Supplemental EIS) and 

nonthreatened and nonendangered coastal and marine birds are expected to be sublethal, primarily 

disturbance-related effects (Chapter 4.2.1.16.2 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 

4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS). Major potential impact-producing factors 

resulting from routine activities for marine birds in the offshore environment include the following:

• habitat loss and fragmentation (Fahrig, 1997 and 1998);

• behavioral effects primarily due to disturbance from OCS helicopter and servicevessel traffic and associated noise (Habib et al., 2007; Bayne et al., 2008);

• mortality due to exposure and intake of OCS oil- and gas-related contaminants, e.g., 

drilling discharges and produced waters (Wiese et al., 2001; Fraser et al., 2006) and 

discarded debris (Robards et al., 1995; Pierce et al., 2004);

• sublethal, chronic effects from air emissions (Newman, 1979; Newman and 

Schreiber, 1988); and

• mortality and energetic costs associated with structure presence and associated light 

(Russell, 2005; Montevecchi, 2006).

A detailed impact analysis of the routine OCS activities associated with proposed CPA Lease Sales 

235, 241, and 247 on coastal and marine birds can be found in Chapter 4.2.1.16.2 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.16 of the WPA 233/CPA 

231 Supplemental EIS.

Overall, impacts to avian species from routine activities are expected to be adverse but not significant.

Impact-producing factors from accidents include oil spills, regardless of size and despite oil-spill 

cleanup activities, including the release of rehabilitated birds. A detailed impact analysis of the accidental 

impacts of OCS activities associated with proposed CPA Lease Sales 235, 241, and 247 on coastal and 

marine birds can be found in Chapter 4.2.1.16.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated 

information is provided in Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS. 

Oil-spill impacts on birds from a CPA proposed action are expected to be adverse but not significant, 

given the number and relatively small size of spills expected over the 40-year life of a CPA proposed 

action (Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS). Impacts of oil-spill cleanup from a CPA 

proposed action are also expected to be adverse, but not significant, but may be negligible depending on 

the scope and scale of efforts. Significant impacts to coastal and marine birds could result in the event of 

a low-probability catastrophic spill, depending on the timing, location, and size of the spill. For 

additional information on a low-probability catastrophic spill, refer to Appendix B. 

Summary and Conclusion

BOEM has reexamined the analysis for coastal and marine birds presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

provided above. At the present time, there is no way to discern if the additional levels of annual 

(>200,000; 50 birds per platform [Russell, 2005] for about 4,000 platforms) or long-term mortality (over 

the life of newly installed platforms) for any of the affected trans-Gulf migrant species considered herein 

results in population-level impacts (Russell, 2005, Chapters 17 and 18). Given what we know about the 

life-history characteristics of many of these species (e.g., age at first reproduction, clutch size, and nest 

success), the potential for major population-level impacts seems relatively low (Arnold and Zink, 2011, 

page 2). Various Internet sources that may be pertinent to the CPA were examined to assess recent 

information regarding this resource. No new significant information was discovered that would alter the 

impact conclusion for these coastal and marine birds presented in the 2012-2017 WPA/CPA Multisale 
4-124 Central Planning Area Lease Sales 235, 241, and 247 EIS

EIS and WPA 233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-

2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

A detailed impact analysis of the coastal and marine birds for a CPA proposed action can be found in 

Chapters 4.2.1.16.1, 4.2.1.16.2, and 4.2.1.16.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated 

information is provided in Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS, all of which are 

hereby incorporated by reference. The following is an analysis of the cumulative impacts to coastal and 

marine birds. Additional information on impacts to birds and results from avian monitoring related to the 

Deepwater Horizon explosion, oil spill, and response can be found in Chapter 4.2.1.16.1 of the 2012-2017 

WPA/CPA Multisale EIS and Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS (Tables 4-8 

and 4-12 through 4-15 of the 2012-2017 WPA/CPA Multisale EIS; refer also to USDOI, FWS, 2011a). 

The incremental contribution of a CPA proposed action to the cumulative impact is considered adverse 

but not significant. 

A more detailed discussion of catastrophic OCS oil- and gas-related events can be found in 

Appendix B. Information regarding a CPA proposed action and the associated activity levels and oilspill information can be found in Tables 3-2 and 3-4 of this Supplemental EIS and in Tables 3-12, 3-18, 

and 3-21 of the 2012-2017 WPA/CPA Multisale EIS.

Background/Introduction 

This cumulative analysis considers impact-producing factors that may adversely affect populations of 

threatened and endangered avian species, as well as nonthreatened and nonendangered species, related to 

OCS oil- and gas- and non-OCS oil- and gas-related activities. For simplicity sake, both listed and 

nonlisted avian species are considered together, although it is recognized that potential impacts from OCS 

oil- and gas-related activities may have relatively greater overall negative effects to listed species than 

nonthreatened and nonendangered species.

Several OCS oil- and gas-related impact-producing factors could potentially affect coastal and marine 

birds, including the following: air pollution; degradation of water quality; oil spills and any improperly 

directed spill response as a result of OCS activity; structure lights and structure lighting; aircraft and 

vessel traffic and noise; maintenance and use of navigation waterways; habitat loss from coastal facility 

and OCS support structure construction; new pipeline landfalls; and impacts from OCS oil- and gasrelated trash and debris.

In addition to the factors listed above, there are several non-OCS oil- and gas-related impactproducing factors that could potentially impact coastal and marine birds. These factors include the 

following: air pollution; habitat loss, alteration, and fragmentation associated with commercial and 

residential construction and industrial growth; water pollution including State or tanker oil- and gasrelated spills and any spill-response activities and pollution of coastal waters resulting from municipal, 

industrial, and agricultural runoff and discharge; aircraft and vessel (including military) activities and 

noise; nonconsumptive and consumptive recreation; maintenance and use of navigation waterways; 

collisions with anthropogenic structures; predation; diseases; climate change and related impacts; impacts 

from storms and floods; fisheries interactions; and trash and debris.

OCS Oil- and Gas-Related Impacts 

Air Pollutants

Air pollutants include the amount of sulfur dioxide and other regulated pollutants (Chapter 4.1.1.1 of 

this Supplemental EIS, Chapter 4.2.1.1 and Table 4-1 of the 2012-2017 WPA/CPA Multisale EIS, and 

Chapter 4.2.1.1 of the WPA 233/CPA 231 Supplemental EIS) expected to be released due to a CPA 

proposed action, as well as from prior and future OCS lease sales. These pollutants may adversely affect 

coastal and marine birds and their habitats (Chapter 4.2.1.16.2 of the 2012-2017 WPA/CPA Multisale EIS

and Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS). Pollutant emissions into the 

atmosphere from OCS oil- and gas-related activities under the cumulative analysis are expected to have 

minimal effects on offshore air quality because of the prevailing atmospheric conditions, emission 
Description of the Environment and Impact Analysis 4-125

heights, and pollutant concentrations, as regulated by USEPA (Wilson et al., 2010, Tables 8-1 and 8-2). 

Onshore impacts to air quality from emissions under the OCS oil- and gas-related cumulative analysis are 

expected to be within both PSD Class I and Class II allowable increments, as applied to the respective 

subareas. Emissions of pollutants into the atmosphere under the OCS oil- and gas-related cumulative 

analysis are projected to have minimal effects on onshore air quality because of the atmospheric regime, 

emission rates (Table 4-1 of the 2012-2017 WPA/CPA Multisale EIS), and the distance of these 

emissions from the coastline. Increases in onshore annual average concentrations of NOx, SOx, and PM10

under the OCS oil- and gas-related cumulative analysis are estimated to be less than PSD Class I and 

Class II allowable increments for the respective subareas as per both the steady-state and plume 

dispersion analyses, and they are assumed to be below concentrations that could harm coastal and marine 

birds (Chapter 4.1.1.16 of this Supplemental EIS, Chapter 4.2.1.16.2 of the 2012-2017 WPA/CPA 

Multisale EIS, and Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS; also refer to Newman, 

1979; Newman and Schreiber, 1988).

For coastal and marine birds, direct impacts (on individuals) and indirect impacts (on habitat or food 

supply) due to air quality under the OCS oil- and gas-related cumulative analysis may include chronic, 

sublethal effects leading to overall reduced recruitment. The incremental contributions of offshore 

emissions are below or within those allowed by USEPA, but it is uncertain to what extent air pollutants 

from OCS oil- and gas-related activities could adversely impact birds in the GOM region. Nevertheless, 

these impacts would not be expected to rise to population-level impacts across the GOM.

Degradation of Water Quality 

Water quality (Chapter 4.1.1.2 of this Supplemental EIS, Chapter 4.2.1.2 and Tables 3-8, 3-9, and 

3-23 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.2 of the WPA 233/CPA 231 

Supplemental EIS) of coastal environments will be affected by bilge water from service vessels and pointand nonpoint-source discharges from supporting infrastructure. Water quality in marine waters will be 

impacted by the discharges from drilling, production, and platform removal operations. Degradation of 

water quality resulting from factors related to a CPA proposed action, plus those related to prior and 

future OCS lease sales, is expected to adversely impact coastal and marine birds (Chapter 4.1.1.16 of this 

Supplemental EIS, Chapter 4.2.1.16.2 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.16 

of the WPA 233/CPA 231 Supplemental EIS). 

The overall coastal condition of the Gulf Coast estuaries was evaluated from 2003 to 2006 by USEPA 

and was rated 2.4 on a scale of 1 (poor) to 5 (good). This represented an improvement from the early 

1990’s (USEPA, 2012a). The incremental addition related to a CPA proposed action will contribute to 

further degradation of water quality, but this remains a small addition when compared with all other 

natural and anthropogenic sources.

Produced water is an important OCS oil- and gas-related activity factor affecting birds. Pollutants 

discharged into navigable waters of the U.S. are regulated by USEPA under the Clean Water Act of 1972 

and subsequent provisions (33 U.S.C. § 1251 et seq.; Chapter 3.1.1.4 of this Supplemental EIS). 

Specifically, an NPDES permit must be obtained from USEPA under Sections 301(h) and 403 (Federal 

Register, 1980) of the Clean Water Act. From 2000 to 2012, OCS oil- and gas-related activities generated 

between 489.0 and 648.2 MMbbl of produced waters (Chapter 3.1.1.4 and Table 3-5 of this 

Supplemental EIS and Chapter 3.1.1.4 of the 2012-2017 WPA/CPA Multisale EIS). Produced water, 

including its constituent pollutants, is the largest waste stream associated with oil and gas production 

(Veil et al., 2004; Welch and Rychel, 2004; Clark and Veil, 2009). The volume of produced water is not 

constant over time and increases over the life of an individual well (Veil et al., 2004). Produced water is 

comprised of a number of different substances, including trace heavy metals, radionuclides, sulfates, 

treatment chemicals, produced solids, and hydrocarbons (Veil et al., 2004). Impacts to birds from 

pollutants remaining in produced water may be from ingestion or contact (direct) or from the changes in 

the abundance, distribution, or composition of preferred foods (indirect). O’Hara and Morandin (2010) 

documented measurable oil transfer to feathers and impacts to feather microstructure at sheen thickness as 

low as 0.1-0.3 micrometers. Even a light coating of hydrocarbons and other substances found in 

produced water can negatively affect feather microstructure, potentially compromising its buoyancy, 

insulation (i.e., thermoregulatory function and capacity), and flight characteristics (Stephenson, 1997; 

O’Hara and Morandin, 2010). Analyses herein are based, in part, on the following assumptions: (1) the 

regulatory limits established by USEPA eliminate or significantly reduce the potential for negative effects 
4-126 Central Planning Area Lease Sales 235, 241, and 247 EIS

to most birds; and (2) produced water and its constituent pollutants will be diluted simply as a function of 

the dilution potential of the ocean, minimizing potential harm to birds. BOEM relies on self-reporting 

and self-monitoring by individual companies relative to produced waters. There is uncertainty as to the 

potential effects of this routine activity on seabirds that overlap spatially and temporally with producedwater discharge events in the CPA (Stephenson, 1997; Wiese et al., 2001; Burke et al., 2012).

Platform and Pipeline Oil Spills and Any Improperly Directed Spill-Response Activities

The potential effects associated with accidental oil spills are only briefly discussed here. A more 

detailed discussion of oil-spill effects/impacts to avian resources (birds) is provided in Chapter 4.1.1.18

of this Supplemental EIS, Chapter 4.2.1.18.3 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 

4.2.1.18 of the WPA 233/CPA 231 Supplemental EIS. Oil spills have the greatest potential to impact 

coastal and marine birds (Tables 4-8, 4-12, and 4-13 of the 2012-2017 WPA/CPA Multisale EIS). 

Mortality is associated with oil spills or chronic oil pollution (Wiese and Robertson, 2004; Wilhelm et al., 

2007; Camphuysen, 2010). It is well understood that the anthropogenic input of accidental spills varies 

temporally and, in the GOM, the years in which major hurricanes occurred resulted in a higher frequency 

of spills as well as a greater annual volume (USDOI, MMS, 2009b; Anderson et al., 2012). Oil spills and 

chronic oil pollution both result in the direct mortality of seabirds worldwide and result in major avian 

losses regionally and locally (Newton, 1998, pages 429-431; also refer to Table 4-15 of the 2012-2017 

WPA/CPA Multisale EIS). Use of waterbird, marshbird, shorebird, and seabird feeding areas at the sea 

surface and at the intertidal wetland zone, where spilled oil may accumulate, makes many avian species 

extremely vulnerable to spilled oil (Tables 3-11, 3-12, 3-17, 3-18, and 3-21 of the 2012-2017 WPA/CPA 

Multisale EIS). Depending on the timing and location of the spill, even small spills can result in major 

avian mortality events (refer to Dunnet, 1982; Piatt et al., 1990; Castège et al., 2007). One or many 

episodes of exposure to small amounts of oil may result in sublethal impacts on birds, with the potential 

to impact preferred food resources through changes in distribution and abundance (i.e., availability) of 

preferred foods (Golet et al., 2002). Mortality from oil spills is often related to numerous symptoms of 

toxicity. Data on spill size, frequency, and source are given in Tables 3-11, 3-12, and 3-21 of the 2012-

2017 WPA/CPA Multisale EIS.

The extensive oil and gas industry operating in the Gulf area may have caused low-level, chronic, 

petroleum contamination of coastal waters (Tables 3-11, 3-17, 3-18, and 3-23 of the 2012-2017 

WPA/CPA Multisale EIS; Holdway, 2002; Jernelöv, 2010). Outside of a low-probability catastrophic 

event, petroleum spills or releases that result from a CPA proposed action or OCS energy program would 

be expected to be small, particularly when compared with naturally occurring seeps in the GOM (Tables 

3-8 and 3-9 of the 2012-2017 WPA/CPA Multisale EIS). Nevertheless, lethal effects are expected 

primarily from uncontained, inshore oil spills and associated spill-response activities in wetlands and 

other biologically sensitive coastal habitats (National Audubon Society, Inc., 2010; USDOI, FWS, 2010). 

Recruitment of birds and a population’s recovery from a major mortality event may take many years, 

depending upon the species and its life-history strategy (Table 4-13 of the 2012-2017 WPA/CPA 

Multisale EIS; Figures 4-18 and 4-19 of the 2012-2017 WPA/CPA Multisale EIS). Long-term effects, in 

some cases, may persist for ≥20 years (e.g., Peterson et al., 2003). Though the Deepwater Horizon

explosion, oil spill, and response only resulted in the collection of >7,000 birds (Figure 4-17 of the 2012-

2017 WPA/CPA Multisale EIS), the total model-estimated mortality associated with this spill has not yet 

been determined. The effects on impacted populations are presently poorly understood, though speciesspecific life-history traits will largely determine a given species response to the spill (Table 4-13 of the 

2012-2017 WPA/CPA Multisale EIS). Refer to Anderson et al. (2012) for additional information specific 

to OCS oil- and gas-related oil spills. A more detailed discussion of catastrophic OCS oil- and gasrelated events can be found in Appendix B. 

Structure Lights and Structure Presence 

Migratory land birds may be impacted by OCS oil- and gas-related attraction to platforms, nocturnal 

circulation (night flights) around platforms, and collision with platforms. Every spring, about 300 million 

migratory landbirds, mostly neotropical passerines, cross the Gulf of Mexico from wintering grounds in 

Latin America to breeding grounds north of the Gulf of Mexico (Russell, 2005). Migration peaks from 

mid-March through the end of May. The reverse migration is repeated again in the fall with a peak 
Description of the Environment and Impact Analysis 4-127

around mid-August through early November (Russell, 2005). Migrants sometimes arrive at platforms 

shortly after night fall or later and proceed to circle those platforms (referred to as a nocturnal circulation 

event) for variable periods ranging from minutes to hours (Russell, 2005). Nocturnal circulation events 

around platforms may create lethal effects from collisions with platforms (Table 4-7 of the 2012-2017 

WPA/CPA Multisale EIS), acute sublethal stress from energy loss, and increased predation risks. At 

present, it is unknown if birds participating in nocturnal circulation events actually have sufficient energy 

reserves post-event to successfully complete their migration. It is estimated that collisions with platforms 

in the GOM leads to an annual mortality of 200,000-321,000 birds (Table 4-7, footnote 5 of the 2012-

2017 WPA/CPA Multisale EIS). Conservatively, a CPA proposed action may increase this level of 

mortality by 1,750-3,350 birds/year. Over the life of the entire platform archipelago, a range of 

7.6-12.2 million birds may be killed, primarily due to collisions (Table 4-7, footnote 5 of the 2012-2017 

WPA/CPA Multisale EIS). Mitigating measures such as changing the lighting type, light color, and/or 

light intensity may decrease the attraction to platforms and the associated collision risk to migratory birds 

(Wiese et al., 2001; Montevecchi, 2006) and may potentially reduce the frequency and duration of 

nocturnal circulation events associated with well-lit (standard white lights) platforms.

It is uncertain if this level of mortality has population-level effects for any of the species involved, but 

it appears unlikely because of what is known of their life-history strategies (e.g., age at first reproduction, 

clutch size, nest success, etc.) (Arnold and Zink, 2011, page 2).

Though presently there are no mitigations in place to address circulation events and attraction of birds 

to platforms and the associated collision risk, BOEM has recently proposed a study to determine if 

changes to present lighting systems on platforms might reduce associated avian mortality. The attraction 

of birds by visible light varies with the wavelength of the light and may not happen (Poot et al., 2008).

Aircraft and Vessel Traffic and Noise from Helicopters and Service Vessels

Helicopter and service-vessel traffic related to OCS oil- and gas-related activities would likely disturb 

the behavior of birds (at least temporarily). Effects tend to manifest themselves through behavioral 

changes such as decreased foraging time, reduced foraging efficiency, and increased energy expenditure 

due to flight associated with a disturbance. The Federal Aviation Administration (Advisory Circular 

91-36C) and corporate helicopter policy states that helicopters must maintain a minimum altitude of 

700 ft (213 m) while in transit offshore and 500 ft (152 m) while working between platforms. When 

flying over land, the specified minimum altitude is 1,000 ft (305 m) over unpopulated areas or across 

coastlines and 2,000 ft (610 m) over populated areas and biologically sensitive areas such as wildlife 

refuges and national parks. The net effect of OCS oil- and gas-related flights on coastal and marine birds

is expected to result in temporary, often sporadic disturbances, which may result in the displacement of 

localized flocks. Service vessels are expected to use selected nearshore and coastal (inland) navigation 

waterways and are further expected to adhere to guidelines established by USCG for reduced vessel 

speeds within inland areas. Routine presence and low speeds of service vessels within these waterways is 

expected to reduce the disturbance effects from service vessels on nearshore and inland populations of 

coastal and marine birds. It is estimated that the effects of both OCS oil- and gas-related and non-OCS 

oil- and gas-related vessel traffic on birds within coastal areas are not substantial.

For a more detailed discussion of disturbance-related impacts, refer to Chapter 4.1.1.16 of this 

Supplemental EIS, Chapter 4.2.1.16.2 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.16 

of the WPA 233/CPA 231 Supplemental EIS.

Maintenance and Use of Navigation Waterways 

Construction of navigation canals for OCS oil- and gas- related development have generated 

substantial adverse impacts to coastal wetlands (Ko and Day, 2004; Morton et al., 2006; Day et al., 2007; 

Figures 3-5 and 3-7 of the 2012-2017 WPA/CPA Multisale EIS). Initial impacts are locally substantial 

but largely limited to where canals and channels pass through wetlands. Periodic maintenance dredging is 

necessary and expected in existing OCS oil- and gas-related navigation channels through barrier passes 

and associated bars (Johnston et al., 2009). Much of the impacts from OCS oil- and gas-related oil and 

gas development on coastal wetlands has already occurred. From 1998 through 2004, wetland losses 

from all causes for all coastal wetland types were estimated at 442,200 ac (178,952 ha) (Stedman and 

Dahl, 2008; Engle, 2011, Table 1). Current channels should not be altered dramatically as a result of a 
4-128 Central Planning Area Lease Sales 235, 241, and 247 EIS

CPA proposed action. In addition, no new channels will be required by a CPA proposed action (refer to 

Chapters 3.3.4.3 and 4.1.1.4 of this Supplemental EIS for more information on navigation canals).

Habitat Loss, Alteration, and Fragmentation Resulting from OCS Oil- and Gas-Related 

Coastal Facility Construction and Development 

Under the cumulative activities scenario, factors contributing to coastal landloss or modification 

include the construction of 0-1 gas processing plants for a CPA proposed action, as well as other 

associated roads, pads, and facilities (for existing installations and transportation bases and various types 

of infrastructure, refer to Tables 3-13, 3-15, and 3-16 and Figures 3-5, 3-6, and 3-7 of the 2012-2017 

WPA/CPA Multisale EIS). The realized footprints of this construction tend to be relatively small based 

on an acreage basis. The OCS activities that include oil and gas processing terminals and associated 

roads and infrastructure result in the destruction or fragmentation of otherwise suitable avian habitats and 

can force affected individuals to disperse to other nonimpacted habitats, assuming it is available and of 

similar or greater quality. In the offshore environment, disturbance-related effects can result in temporary 

functional loss of habitat, as individuals are forced to disperse from impacted sites. Many of the 

overwintering shorebird species remain within relatively well-defined, winter-use areas throughout the 

season, and some species exhibit among-year wintering site fidelity, at least when not disturbed by

humans. These species are particularly vulnerable to localized impacts, resulting in habitat loss or 

fragmentation, unless they disperse to other favorable habitats when disturbed. Cumulative activities 

related to a CPA proposed action will likely contribute to further loss, alteration, and fragmentation of 

avian habitat although certainly at a much smaller spatial scale than non-OCS residential, commercial, 

and industrial construction and development activities.

Pipeline Landfalls

Under the cumulative activities scenario, factors contributing to coastal landloss or modification 

include the construction of 0-1 pipeline landfalls for a CPA proposed action. From 1996 through 2009, 

there were 12 OCS oil- and gas-related pipeline landfalls in Louisiana and Texas (Table 3-16 of the 2012-

2017 WPA/CPA Multisale EIS). Refer to Figure 3-5 of the 2012-2017 WPA/CPA Multisale EIS for 

transitioning pipelines in Louisiana and Texas. Refer to Chapters 4.1.1.4 of this Supplemental EIS for 

more details regarding the impacts to wetlands; also refer to reviews by Gosselink et al. (1998). Dahl 

(2006) estimated an annual loss rate of 5,540 ac (2,242 ha) for the intertidal estuarine and marine wetland 

class, mostly in Louisiana, from all impacting factors.

Trash and Debris 

Coastal and marine birds may experience chronic physiological stress from sublethal exposure to or 

intake of debris-related contaminants or discarded debris associated with OCS oil- and gas-related 

activities. This may result in disturbances to and displacement of single birds or in some cases entire 

flocks. Much of the floating material discarded from vessels and structures offshore presumably drifts 

ashore, remains within coastal waters, or eventually sinks. These materials may include lost or discarded 

fishing gear such as gill nets and monofilament lines, which cause the greatest overall damage to birds 

(Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS; Tasker et al., 2000; Dau et al., 2009; Ryan et al., 

2009).

It is believed that coastal and marine birds are less likely to become entangled in or ingest OCS oiland gas-related trash and debris as a result of BSEE’s regulations (NTL 2012-BSEE-G01) regarding the 

disposal of equipment, containers, and other materials into offshore waters by lessees (30 CFR § 

250.300(c)). In addition, MARPOL, Annex V, Public Law 100-220 (101 Statute 1458), prohibits the 

disposal of any plastics at sea or in coastal waters (effective January 1, 1989).

Non-OCS Oil- and Gas-Related Impacts

There are no mitigations in place that consider potential non-OCS oil- and gas-related effects on avian 

resources due to climate change and habitat impacts. A Memorandum of Understanding between this 

Agency and FWS regarding the conservation of migratory birds was signed in June 2009 (USDOI, FWS 

and USDOI, MMS, 2009).
Description of the Environment and Impact Analysis 4-129

Non-OCS Oil- and Gas-Related Air Pollutants

Air pollutants include the amount of sulfur dioxide (and other regulated pollutants; refer to Chapter 

4.1.1.1 of this Supplemental EIS, Chapter 4.2.1.1 and Table 4-1 of the 2012-2017 WPA/CPA Multisale 

EIS, and Chapter 4.2.1.1 of the WPA 233/CPA 231 Supplemental EIS) expected to be released due to a 

CPA proposed action, as well as from prior and future OCS lease sales, and State oil and gas activity. 

These pollutants may adversely affect coastal and marine birds and their habitats (Chapter 4.1.1.16 of 

this Supplemental EIS, Chapter 4.2.1.16.2 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 

4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS). Pollutant emissions into the atmosphere from the 

activities under the non-OCS oil- and gas-related cumulative analysis are expected to have minimal 

effects on offshore air quality because of the prevailing atmospheric conditions, emission heights, and 

pollutant concentrations, as regulated by USEPA (Wilson et al., 2010, Tables 8-1 and 8-2). Emissions of 

pollutants into the atmosphere under the non-OCS oil- and gas-related cumulative analysis are projected 

to have minimal effects on onshore air quality because of the atmospheric regime, emission rates (Table 

4-1 of the 2012-2017 WPA/CPA Multisale EIS), and the distance of these emissions from the coastline. 

Increases in onshore annual average concentrations of NOx, SOx, and PM10 under the non-OCS oil- and 

gas-related cumulative analysis are estimated to be less than PSD Class I and Class II allowable 

increments for the respective subareas as per both the steady-state and plume dispersion analyses, and 

they are assumed to be below concentrations that could harm coastal and marine birds (Chapter 4.1.1.16

of this Supplemental EIS, Chapter 4.2.1.16.2 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 

4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS; also refer to Newman, 1979, and Newman and 

Schreiber, 1988).

For coastal and marine birds, direct impacts (on individuals) and indirect impacts (on habitat or food 

supply) due to air quality under the non-OCS oil- and gas-related cumulative analysis may include 

chronic, sublethal effects leading to overall reduced recruitment. Nevertheless, these impacts would not 

be expected to rise to population-level impacts across the GOM.

Habitat Loss, Alteration, and Fragmentation Associated with Commercial and Residential 

Construction and Industrial Growth 

Habitat loss, alteration, and fragmentation has the potential to affect all aspects of an avian 

community’s annual life cycle and the overall population size for some species of birds that occur in the 

Gulf of Mexico (Arlt and Pärt, 2007). Much habitat loss, alteration, and fragmentation occurs in the 

nearshore environment or onshore and is not OCS oil- and gas-related, e.g., commercial and residential 

construction and industrial development. Non-OCS oil- and gas-related impacts on habitat operate in a 

way similar to the OCS oil- and gas-related impacts on habitat discussed previously in this chapter. 

Cumulative activities will stress individuals and their populations, causing them to avoid or emigrate from 

traditional breeding, feeding, or wintering areas or alter migratory routes. Some of the species may be 

declining (Table 4-14 of the 2012-2017 WPA/CPA Multisale EIS) and are further being displaced from 

areas along the coast (and elsewhere) as a result of the destruction of or encroachment on their preferred 

habitat(s) (Andrén, 1994; Withers, 2002). As these birds emigrate to and settle in undisturbed areas of 

similar habitat (assuming it is available), their presence may increase intra- and interspecific competition 

for space and food (Goss-Custard, 1980).

Bird habitat loss, alteration, and fragmentation associated with commercial and residential 

development and industrial growth are probably occurring at a faster pace and on a spatial scale 

exceeding that compared with OCS oil- and gas-related activities. Avian species are adaptable with 

ephemeral settling patterns, but the pace with which they can adapt may be too slow compared with the 

pace with which human-induced habitat loss, alteration, or fragmentation is occurring across the U.S. (and 

Canada). This appears to be resulting in some species of breeding birds making poor “choices” (i.e., 

selecting habitats that negatively affect survival or fecundity; “sinks” or “traps”), at least in the short term 

(Clark and Shutler, 1999; Kristan, 2003; Battin, 2004). Delayed responses to habitat loss by some avian 

species are likely to occur when the rate of habitat loss or modification and/or environmental perturbation 

(e.g., climate change) exceeds the demographic potential of the population decoupling population 

dynamics from landscape dynamics (With et al., 2008). Habitat loss and fragmentation may be occurring 

at multiple spatial scales or across multiple areas, i.e., breeding, staging, and wintering, and therefore, 

connectivity of suitable habitats is reduced (Haig et al., 1998; Mönkkönen and Reunanen, 1999). Also, 
4-130 Central Planning Area Lease Sales 235, 241, and 247 EIS

access to resources (either habitat itself or food resources) within these sites may be limiting or may 

become limiting. That is, resources are no longer available in sufficient quantities and/or of sufficient 

quality to meet the demands of migration and breeding (Goss-Custard et al., 2006; Newton, 2006; 

Skagen, 2006). Coastal habitat loss, alteration, and fragmentation are a major concern for those interested 

in managing these migratory bird populations (Erwin, 1996; USDOI, FWS, 2008; North American Bird 

Conservation Initiative, 2009). Development, both commercial and residential, was recognized as a 

major threat to remaining coastal habitats, ecological diversity, wildlife populations, and species 

persistence in the southeastern U.S. by Czech and Krausman (1997) and Czech et al. (2000).

Refer to Chapter 4.1.1.4 of this Supplemental EIS, Chapters 4.2.1.4.1-4.2.1.4.3 of the 2012-2017 

Multisale EIS, and Chapter 4.2.1.4 of the WPA 233/CPA 231 Supplemental EIS for more details 

regarding impacts to wetlands. Dahl (2006) estimated an annual loss rate of 5,540 ac (2,242 ha) for the 

intertidal estuarine and marine wetland class, mostly in Louisiana, from all impacting factors.

Tanker Oil Spills and Spills Related to Oil and Gas Activities in Coastal State Waters and 

Spill-Response Activities

Most offshore non-OCS oil- and gas-related spills occur from vessel and barge operations (Helm 

et al., 2008; Tables 3-8, 3-9, and 3-11 of the 2012-2017 WPA/CPA Multisale EIS). Based on the OSRA

model for coastal spills >1,000 bbl, the estimated total number of spills is 3 per 6 years for the total of 

non-OCS oil- and gas-related sources; for offshore spills >1,000 bbl, the estimated total number of spills 

for non-OCS oil- and gas-related sources is <1 per year for tank ships and <1 per year for tank barges. In 

summary, the use of waterbird, marshbird, shorebird, and seabird feeding areas at the sea surface and at 

the intertidal wetland zone, where spilled oil tends to accumulate makes many avian species extremely 

vulnerable to spilled oil (Tables 4-8, 4-12, and 4-13 of the 2012-2017 WPA/CPA Multisale EIS). Oil 

spills in the cumulative case have the greatest potential impact to coastal and marine birds (e.g., Tables 4-

8 and 4-15 of the 2012-2017 WPA/CPA Multisale EIS). 

Oil-spill-related impacts on birds from the total cumulative scenario are expected to range from 

moderate to adverse, but not significant, in the absence of another major spill. The incremental increase 

of oil spills from a CPA proposed action to the total cumulative impacts is also expected to be moderate 

to adverse but not significant.

Pollution of Coastal Waters Resulting from Municipal, Industrial, and Agricultural Runoff 

and Discharge 

There exists a wide variety of contaminant inputs into coastal waters bordering the Gulf of Mexico 

(USEPA, 2012a; USDOC, NOAA, 2011a). Non-OCS oil- and gas-related activities and natural processes 

that can impact marine water quality include bilge water discharges from large ships and tankers, and 

coastal pollutants that are transported away from shore, including municipal, industrial, and agricultural 

runoff, river input, sewerage discharges, industrial discharge, and natural seepage of oil and gas. 

Contaminants from non-OCS oil- and gas-related pollution of coastal waters resulting from runoff and 

discharge may have acute (single episode) or chronic (multiple episode) impacts to avian populations in 

the GOM and impacts may be lethal or sublethal. The dominant pollution source is the large volume of 

water from the Mississippi River, which drains over two-thirds of the contiguous United States, creating a 

seasonal zone of hypoxia offshore at the continental shelf (Rabalais et al., 2001, 2002a, and 2002b). 

Major activities that have added to the contamination of Gulf coastal waters include the petrochemical 

industry, agriculture, forestry, urban expansion, extensive dredging operations, municipal sewerage 

treatment processes, marinas and recreational boating, maritime shipping, hydro-modification activities, 

large commercial waste disposal operations, livestock farming, manufacturing industry activities, power 

plant operations, and pulp and paper mills (Schmitt, 1998; White and Wilds, 1998). Vessel traffic is 

likely to impact water quality through routine releases of bilge and ballast waters, chronic fuel and tank 

spills, trash and debris, and domestic and sanitary discharges. All of these factors, as well as 

sedimentation, greatly contribute to the diminishing water quality in the GOM and associated rivers and 

wetlands within the southeastern United States (USEPA, 2012a; USDOC, NOAA, 2011a). Refer to 

Chapter 4.1.1.2 for more information on coastal water quality.
Description of the Environment and Impact Analysis 4-131

Aircraft and Vessel Traffic (Including Military Activities)

Helicopters may have more impact on bird behavior than airplanes, probably because of a much 

higher noise level associated with the prop wash (Komenda-Zehnder et al., 2003; Rojek et al., 2007). 

Military activities will include vessel and aircraft traffic. Ward et al. (1999) recommended that all aircraft 

follow not only the Federal Aviation Administration’s (1984) minimum altitude of 610 m (2,000 ft) but 

also adopt a lateral buffer distance of 1.6 km (~1 mi). Based on results for disturbance to wintering 

waterbirds (mostly ducks), Komenda-Zehnder et al. (2003) recommended minimum flight altitudes 

(above sea level) of 450 m (1,476 ft) for helicopters and 300 m (984 ft) for airplanes. Disturbance effects 

(e.g., air and vessel traffic) can have variable impacts to avian populations depending on the type, 

intensity, duration, distance to and frequency of the disturbance, as well as due to species-specific 

differences in tolerance levels (Blumstein, 2006; Blumstein et al., 2005; Wright et al., 2010). 

Disturbance-related impacts typically result in behavioral changes, decreasing available habitat, and 

decreases in reproductive effort or nest success. In the CPA, disturbance impacts from helicopter traffic 

and service vessels (Tables 3-2 and 3-4 of this Supplemental EIS and Table 3-13 of the 2012-2017 

WPA/CPA Multisale EIS) represent incremental increases to the total cumulative scenario. Impacts to 

affected avian populations are expected to range from negligible to moderate (Chapter 4.1.1.16 of this 

Supplemental EIS, Chapters 4.2.1.16.1-4.2.1.16.3 of the 2012-2017 WPA/CPA Multisale EIS, and 

Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS).

Nonconsumptive and Consumptive Recreation 

Impacts of nonconsumptive recreation depend on many factors, including species and type of 

recreation and associated disturbance. Even visitation by those most interested in conserving wildlife 

may result in birds abandoning areas that wildlife managers are trying to protect (Burger and Gochfeld, 

1998; Klein, 1993). Ecotourists (including bird watchers and wildlife photographers) and outdoor 

recreationists are not likely to be aware of the negative impacts that their presence may have on wildlife 

(Carney and Sydeman, 1999). Ecotourists can introduce high levels of disturbance to nesting waterbird 

colonies (Rodgers and Schwikert, 2002 and 2003). Ecotourists often closely approach birds, return to the 

same sites repeatedly, and visit sites year-round.

Energy cost in birds is highest for flight. Fleeing from disturbance may affect feeding behavior and 

the effects of predation in complex ways; staying put may increase or decrease fitness.

Recreational vessel traffic is assumed to be a much greater source of impact to birds in coastal 

habitats relative to those offshore.

Despite the number of waterfowl killed annually (consumptive recreation) under Federal hunting 

laws, duck and goose populations remain strong.

For additional discussion on the topic, refer to Chapter 4.1.1.14 of this Supplemental EIS, Chapter 

4.1.1.14.1 of the 2012-2017 Multisale EIS; and Chapter 4.1.1.14 of the WPA 233/CPA 231 Supplemental 

EIS.

Maintenance and Use of Navigation Waterways 

Adverse impacts related to the construction of navigation canals for oil and gas development in State 

waters and for commercial shipping and recreational/fishing boat traffic have generated substantial 

impacts to coastal wetlands (Ko and Day, 2004; Morton et al., 2006; Day et al., 2007; Figures 3-5 and 3-7 

of the 2012-2017 WPA/CPA Multisale EIS). Initial impacts are locally substantial but largely limited to 

where canals and channels pass through wetlands. Periodic maintenance dredging is necessary and 

expected in existing non-OCS oil- and gas-related navigation channels through barrier passes and 

associated bars (Johnston et al., 2009). Much of the impact from State oil and gas development on coastal 

wetlands has already occurred. The continued long-term effects of saltwater intrusion, wind and wave 

action from storms, and erosion from wave action created by State oil- and gas-related, commercial 

shipping, and recreational vessel traffic and recreational/commercial fishing boats continue to take their 

toll on coastal salt marshes and associated wildlife and fisheries communities in the Gulf Coast region 

(Gosselink et al., 1998). From 1998 through 2004, wetland losses from all causes for all coastal wetland 

types were estimated at 442,200 ac (178,952 ha) (Stedman and Dahl, 2008; Engle, 2011, Table 1).
4-132 Central Planning Area Lease Sales 235, 241, and 247 EIS

Collisions of Coastal and Marine Birds with Various Anthropogenic Structures 

Wide-scale, long-term, standardized and systematic assessments of bird collisions with manmade 

structures are limited (Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS; Erickson et al., 2001). The 

most important structural features related to collision risk may be size, height, light intensity, and light 

color associated with a given structure (Bevanger, 1994 and 1998). No hypotheses for the apparent 

attraction of birds, especially nocturnally migrating songbirds, to lights have been conclusively supported 

(Drewitt and Langston, 2008; Martin, 2011). The placement of elevated structures along migration 

corridors appear to be particularly problematic for birds, resulting in increased collision risk and collisionrelated mortality. Warning lights for aircraft on towers >200 ft (61 m) are mandatory in the United States 

(Drewitt and Langston, 2008). Combining collision mortality estimates for communication towers, power 

lines, and window strikes, the total mortality may be approaching 1 billion birds killed annually 

(Manville, 2005a and 2009; Klem, 2009).

Predation 

Predation, although a natural process, can be a threat to coastal and marine birds if predator 

populations are artificially high, non-native predators are introduced, or predators have easier access to 

nesting sites because of human activities.

Domestic cats have become an increasingly devastating introduced predator in many ecological 

systems throughout the world. In the U.S. alone, estimates based on the number of domestic cats 

multiplied by average annual bird mortality per cat results in estimates of 468 million to 8.4 billion birds 

killed (Dauphiné and Cooper, 2009 and 2011; Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS). 

The lower range would place domestic cat mortality second only behind collisions with 

windows/buildings (Klem, 2009), whereas if the upper range even remotely approximates reality, then 

domestic cat-related mortality would far exceed all other anthropogenic sources of avian mortality. 

Domestic cats are especially important predators on land birds that are trans-Gulf migrants, preying on 

them while they are on land.

A study done on the Isle Dernieres barrier island complex in Louisiana suggests that colonial nesting 

seabirds are impacted on some barrier island breeding habitat by raccoon, rat, and coyote predation on 

eggs and young (Leumas, 2010).

Diseases

Throughout North America, avian mortality associated with diseases, broadly defined here to include 

lead poisoning, probably results in the death of millions of birds annually (Table 4-7 of the 2012-2017 

WPA/CPA Multisale EIS). Friend and Franson (1999) list seven broad classes of primarily avian 

diseases and under each are varying numbers or kinds of specific diseases. The most commonly 

diagnosed viral diseases were duck plague, paramyxovirus, and West Nile virus, together causing almost 

all deaths due to infectious diseases; fungal and parasitical infections were relatively minor (Newman 

et al., 2007). The impact of influenza viruses on wild animal host survival, reproduction, and behavior 

are almost completely unknown (Vandegrift et al., 2010). LaDeau et al. (2007) stated that “Emerging 

infectious diseases present a formidable challenge to the conservation of native species in the twenty-first 

century.” Avian diseases may become an increasingly important mortality factor to consider, particularly 

since environmental contaminants are prevalent in many ecosystems, and in some cases avian populations 

may be occurring at densities promoting the spread of diseases. Though the level of mortality associated 

with most diseases is unknown, avian death due to various diseases is likely in the millions annually. 

Many diseases are more easily spread amongst individuals at high densities, e.g., botulism in molting 

waterfowl.

Climate Change and Related Impacts 

In general, climate change as it relates to migratory birds may impact certain species in myriad ways. 

Effects may manifest themselves through relatively “simple” range contractions or expansions, either 

elevationally or latitudinally. The relatively recent overlap of species previously segregated in space or 

by microhabitat features may increase interspecific competition for resources, which may lead to changes 

in species composition and abundance. In some cases where long-term data are available, results 
Description of the Environment and Impact Analysis 4-133

unequivocally demonstrate phenological changes like earlier nesting (Møller et al., 2008). Declines 

happened in species that had not changed the timing of nesting in response to changing environmental 

conditions (Møller et al., 2008). It is possible that species that cannot adapt relatively rapidly could incur 

temporal mismatches (Visser et al., 1998 and 2004). Before climate change, timing of departure from the 

wintering grounds tended to be optimized such that peak arrival and/or peak hatching overlapped the peak 

in food resource availability.

Impacts from predicted sea-level rise will affect the availability and distribution of preferred habitats. 

Many species of birds are closely linked to shallow-water habitats, primarily for food resources (e.g., 

marshbirds, waterbirds, and shorebirds) but also for nesting. Numerous species of coastal and marine 

birds are vulnerable to the effects associated with climate change (North American Bird Conservation 

Initiative, 2010). In particular, those species that select low-lying habitats such as islands, beaches, flats, 

dunes, sand bars, gravel bars, dredge spoils, shorelines, estuaries, and similar inshore habitat are 

particularly vulnerable due to annual increases in sea level. Sea-level rise is expected to inundate much of 

the low-lying areas and also increase water depths in areas farther inland. As the sea-level rises, impacts 

from storm surges and flooding will extend farther inland. Also, saltmarsh obligate species (e.g., seaside 

sparrow, Nelson’s sharp-tailed sparrow, yellow rail, black rail, clapper rail, and king rail) are also 

extremely sensitive to loss of salt marsh habitat. Other climate change impacts include increasing seasurface temperature and the increasing frequency and intensity of storms (and associated erosion) 

(Michener et al., 1997). Effects from these various factors will most likely dramatically alter the species 

composition and abundance, as well as the distribution of potentially affected species primarily due to 

major reductions in available habitat and zones shifting inland and secondarily to changes in the 

distribution and abundance of preferred foods.

Storms and Floods 

Coastal storms and hurricanes can often result in the direct mortality of many species of birds, but 

likely the larger impact is to the habitat on which the populations rely. Associated storm surges and 

flooding can destroy active nests and force birds into suboptimal habitats. Nesting territories and colonial 

waterbird and marshbird rookeries with optimum food and/or nest-building materials may also be 

destroyed. Species reliant on the beaches, flats, islands, sand bars, gravel bars, dredge spoil-piles, 

shorelines, estuaries, and other coastal low-lying features for nesting are particularly vulnerable to habitat 

loss or alteration associated with such storms (USDOI, FWS, 2010). Elevated levels of municipal, 

industrial, and agricultural pollutants in coastal wetlands and waters will probably expose greater numbers 

of resident breeding birds and wintering migrants to chronic physiological stress due to these 

contaminants being redistributed across the landscape as a result of storms and flooding (Burger and 

Gochfeld, 2001).

Hurricane-related impacts to birds are provided in more detail in Chapter 4.1.1.16 of this 

Supplemental EIS, Chapter 4.2.1.16.1 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.16 

of the WPA 233/CPA 231 Supplemental EIS.

Fisheries Interactions 

Commercial fisheries may incidentally entangle and drown or otherwise injure birds during fishing 

operations or due to lost or discarded fishing gear (Manville, 2005b; Bull, 2007; Brothers et al., 2010). 

Avian mortality estimates associated with commercial fisheries (i.e., seabird bycatch) is likely on the 

order of high thousands to low millions (Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS). Both 

NMFS and FWS have taken proactive steps to mitigate these losses through modifications to the 

equipment used, fishery closures in certain areas, time-of-year and time-of-day closures by some states, 

and use of fishery observers (Melvin et al., 1999 and 2001; Cooper et al., 2001). With these recent 

changes in policy, procedures, and techniques, cumulative impacts to future bird bycatch of longline 

fisheries on marine birds in the northern Gulf of Mexico should be much reduced. There is likely overlap 

between many species of seabirds, their prey, and some fisheries. Fisheries may impact certain seabird 

populations by removing preferred prey or may alter trophic dynamics by removing top-level predators 

(e.g., bluefin and yellowfin tuna) (Furness, 2003). In addition, substantial quantities of bycatch (i.e., 

nontarget species + offal + discards) are discarded as waste overboard, and though detrimental to the 

ecosystem as a whole (Crowder and Murawski, 1998; Harrington et al., 2005), may actually benefit some 
4-134 Central Planning Area Lease Sales 235, 241, and 247 EIS

species of seabirds (Furness, 2003; Votier et al., 2004). Overharvest of some fish populations, 

particularly top-level predatory fishes, appears to be occurring at unprecedented levels worldwide (Myers 

and Worm, 2003). Unfortunately, the loss of these top-level predators can have unknown and potentially

dramatic effects on marine food-web dynamics and the ocean ecosystem as a whole, including seabird 

populations reliant on various species of smaller prey fish (Furness and Camphuysen, 1997; Piatt et al., 

2007).

Trash and Debris 

Coastal and marine birds may experience chronic physiological stress from sublethal exposure to or 

intake of debris-related contaminants or discarded debris associated with non-OCS oil- and gas-related 

activities. This may result in disturbances to and displacement of single birds or in some cases entire 

flocks. Much of the floating material discarded from State oil and gas vessels and structures offshore as 

well as recreational debris presumably drifts ashore, remains within coastal waters, or eventually sinks. 

These materials may include lost or discarded fishing gear such as gill nets and monofilament lines, 

which cause the greatest overall damage to birds (Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS; 

Tasker et al., 2000; Dau et al., 2009; Ryan et al., 2009).

It is believed that coastal and marine birds are less likely to become entangled in or ingest non-OCS

oil- and gas-related trash and debris as a result of MARPOL, Annex V, Public Law 100-220 (101 Statute 

1458), which prohibits the disposal of any plastics at sea or in coastal waters (effective January 1, 1989).

Summary and Conclusion

Human-induced disturbance effects often tend to get overlooked or underestimated as a potential 

population-limiting factor for birds. The cumulative effect on coastal and marine birds from all sources is 

expected to result in changes in species composition and distribution and in a discernible decline in the 

number of birds that form localized groups or populations. Some of these changes are expected to be 

permanent and possibly result from impacts to and declines in critical habitat for some endangered 

species. However, the incremental contribution of a CPA proposed action to the cumulative impact is 

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

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

sublethal; and some displacement of local individuals or flocks may occur to other habitat, if available.

In general, the net effect of habitat loss from oil spills, OCS pipeline landfalls, and maintenance and 

use of navigation waterways, as well as habitat loss and modification resulting from coastal facility 

construction and development, will probably reduce the overall carrying capacity of the disturbed 

habitat(s). That is, impacted habitats may result in reductions to both species composition (fewer species) 

and abundance (lower numbers) as compared with what the area supported historically. These would be 

the most serious cumulative impacts on birds.

Nocturnal circulation events at platforms are assumed to have mostly sublethal impacts on migrating 

bird populations. However, oil and gas platforms in the GOM (and associated lighting) result in 

collision-related mortality of 200,000-321,000 birds/year (Table 4-7 of the 2012-2017 WPA/CPA 

Multisale EIS); these numbers will increase as a result of a CPA proposed action. Overall, offshore oil 

and gas platform-related avian mortality, though representing an additional source of human-induced 

mortality, represents a small fraction compared with other sources of human-induced mortality. The 

mortality estimates related to offshore oil and gas activities are well below that for vehicles, buildings and 

windows, power lines, and communication towers.

The Deepwater Horizon explosion and spilled oil that made it into the nearshore and coastal 

environment resulted in the loss of ~7,250 birds based on counts of dead and/or oiled birds (Table 4-2 of 

the WPA/CPA 231 Supplemental EIS). This is a low estimate because many individuals were not 

collected. In addition, spill-response activities likely exacerbated impacts, particularly for breeding birds 

nesting on the beaches, barrier islands, and other habitats that were intensively monitored. The total 

number of birds killed by the Deepwater Horizon explosion, oil spill, and response was likely biased low. 

In addition, it will be years before a reliable, model-based estimate of mortality that accounts for 

detection-related issues is provided. At present, the best available information does not provide a 

complete understanding of the effects of the spilled oil or the recovery potential for the most impacted 

species. Unavailable information on the effects on birds, including from the Deepwater Horizon
Description of the Environment and Impact Analysis 4-135

explosion, oil spill, and response (and thus changes to the birds baseline in the affected environment), 

makes an understanding of the cumulative effects less clear. Here, BOEM concludes that the unavailable 

information from this event may be relevant to foreseeable significant adverse impacts to birds. Relevant 

data on the status of seabird populations after the Deepwater Horizon explosion, oil spill, and response 

may take years to acquire and analyze, and impacts from the Deepwater Horizon explosion, oil spill, and 

response may be difficult or impossible to discern from other factors. Therefore, it is not possible for 

BOEM to obtain this information within the timeline contemplated in the NEPA analysis of this

Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable 

information, BOEM’s subject-matter experts have used available scientifically credible evidence in this 

analysis and based upon accepted methods and approaches. Nevertheless, a complete understanding of 

the missing information is not essential to a reasoned choice among alternatives for this Supplemental EIS 

(including the No Action and an Action alternative) for the following reasons. The CPA is an active oil 

and gas region with ongoing (or the potential for) exploration, drilling, and production activities. In 

addition, non-OCS oil- and gas-related activities will continue to occur in the CPA irrespective of a CPA 

proposed action (e.g., fishing, military activities, and scientific research). The potential for effects from 

changes to the affected environment (post-Deepwater Horizon explosion, oil spill, and response), routine 

activities, accidental spills (including low-probability catastrophic spills), and cumulative effects remains 

whether or not the No Action or an Action alternative is chosen under this Supplemental EIS. Impacts on 

birds from either smaller accidental events or low-probability catastrophic events will remain the same.

Disease is often lethal and may take millions of birds annually, but it should be considered a 

“naturally” occurring avian mortality factor unless the pathogen is introduced by humans. Storms and 

floods represent natural, often major disturbances to which exposed organisms are generally adapted. An 

exception would be hurricane-related storm surges, which are exacerbated by coastal wetland loss in 

Louisiana and throughout the northern GOM. Effects from sea-level rise may be particularly severe for 

many species of breeding marsh- and shorebirds as well as several species of wintering shorebirds that 

rely on beaches, flats, dunes, sandbars, gravel bars, shorelines, islands, estuaries, and other low-lying, 

tidally influenced habitats in the Gulf of Mexico . Even a nominal rise in sea level would inundate much 

of this habitat, making it unsuitable for many, if not most, of these species.

In conclusion, the incremental contribution of a CPA proposed action to the cumulative impact is 

considered adverse but not significant when compared with the impacts of non-OCS Program-related 

factors.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A detailed treatment of the potential effects of impact-producing factors on coastal and marine birds

associated with a CPA proposed action can be found in Chapters 4.2.1.16.2 and 4.2.1.16.3 of the 2012-

2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.16 of the WPA 

233/CPA 231 Supplemental EIS. A search of Internet information sources (recent publications on 

NOAA’s, USGS’s, and FWS’s websites), as well as recently published journal articles, was conducted to 

determine the availability of recent information on coastal and marine birds. New information pertinent 

to the consideration of the red knot (Calidris canutus rufa) as a federally threatened species was 

discovered.

The red knot (Calidris canutus rufa) is presently considered a Federal candidate species. It was 

originally (September 2006) considered as a Category 6 Candidate, but it was upgraded (more urgently) 

to a Category 3 Candidate in December 2008. As of September 30, 2013, FWS proposed to list the rufa 

red knot (Calidris canutus rufa) as a threatened species (USDOI, FWS, 2014). Three of the six 

subspecies of red knot occur in North America, all three of which breed in the Arctic (central Canadian 

Arctic and on the north coast of Alaska from the Seward Peninsula to the Canadian border). It uses 

coastal beaches, bays, tidal flats, salt marshes, and lagoons primarily along the Atlantic Coast (a major 

stopover is in Delaware Bay) during spring and fall migration in transit from its breeding grounds in the

Arctic to its wintering grounds at Tierra del Fuego, Argentina, and back. Rather steep declines 

(~505 between the late 1980’s and 2003; Morrison et al., 2004) have been observed in the population that 

departs the central Canadian Arctic in August, embarking on a 15,000-km (9,321-mi) migration to 

northern Brazil and Tierra del Fuego, Argentina (Morrison et al., 2006; Niles et al., 2008). During the fall 

migration, this population stops on its way south in Delaware Bay where individuals almost exclusively 
4-136 Central Planning Area Lease Sales 235, 241, and 247 EIS

consume (and require) large quantities (both in number and volume) of horseshoe crab (Limulus 

polyphemus) eggs to fatten-up prior to departure (Harrington, 2001). On the spring return flight, these 

same birds spend ~2 weeks in the same general area in an effort to recover energy lost (some as much as 

30% lighter) during the migration from the wintering grounds (Niles et al., 2008). This is the single most 

important staging area for this population of red knots. There has been a major increase in the 

commercial fishing harvest of adult horseshoe crabs, likely resulting in major reductions in availability of 

the species that produce the eggs on which the red knots rely (Karpanty et al., 2006; Wells, 2007).

The FWS received its first petition to list this species on August 9, 2004, with two additional 

petitions, both received on August 5, 2005. The associated formal review, which was completed on 

September 12, 2006 (Federal Register, 2006b), indicated a listing priority of 6. Subsequently, FWS has 

completed formal reviews for this species in 2007 (December 6, 2007; Federal Register, 2007), 2008 

(December 10, 2008; Federal Register, 2008a), 2009 (November 9, 2009; Federal Register, 2009), and 

2010 (November 10, 2010; Federal Register, 2010). As indicated above, it is now considered a 

Category 3 Candidate species and is currently being considered to list as threatened (Federal Register, 

2013f). 

Within the Gulf of Mexico region, wintering birds are found primarily in Florida, but the species has 

also been observed in Texas (e.g., Bolivar Flats), Louisiana (e.g., barrier islands and headlands along the 

coast), Mississippi, and Alabama (e-Birds, 2013), and it is considered a State Species of Conservation 

Concern in Florida and Mississippi. Apparently, the numbers of wintering and staging red knots using 

coastal beaches in Gulf Coast States other than Florida have declined dramatically; now more are found 

along the Gulf and Atlantic Coasts of Florida and the Atlantic Coast of Georgia and South Carolina 

(Harrington, 2001; Niles et al., 2008, Figures 8-9 and 11). Both natural (i.e., hurricanes, subsidence, and 

saltwater intrusion) and anthropogenic (i.e., coastal development, oil and gas infrastructure onshore, and 

disturbance) factors influencing coastal wetlands and associated barrier island and beach habitats on the 

wintering and staging areas in the southeastern U.S. may be contributing to the change in distribution 

(and possibly population declines) of red knots over time (Wells, 2007; Niles et al., 2010).

The Deepwater Horizon explosion, oil spill, and response activities that made it into the nearshore 

and coastal environment resulted in the loss of ~7,250 birds across all Gulf of Mexico planning areas 

(Table 4-2 of the WPA 233/CPA 231 Supplemental EIS). In addition, spill-response activities likely 

exacerbated impacts, particularly for breeding birds nesting on the beaches, barrier islands, and other 

habitats that were intensively monitored. The total number of birds killed by the Deepwater Horizon

explosion, oil spill, and response was likely biased low (Table 4-2 of the WPA 233/CPA 231 

Supplemental EIS). In addition, it will be years before a reliable, model-based estimate of mortality that 

accounts for detection-related issues is provided (e.g., Flint et al., 1999; also refer to Byrd et al., 2009). 

At present, the best available information (e.g., Henkel et al., 2012) does not provide a complete 

understanding of the effects of the spilled oil or the recovery potential for the most impacted species 

(Tables 4-12, and 4-13 of the 2012-2017 WPA/CPA Multisale EIS and Table 4-2 of the WPA 233/CPA 

231 Supplemental EIS). 

Unavailable information on the cumulative effects to coastal and marine birds, including information 

from after the Deepwater Horizon explosion, oil spill, and response (and thus related changes to the avian 

baseline in the affected environment), makes an understanding of the potential impacts from a CPA 

proposed action less clear. BOEM concludes that the unavailable information from these events may be 

relevant to foreseeable significant adverse impacts to coastal and marine birds. Nevertheless, relevant 

data on the status of bird populations after the Deepwater Horizon explosion, oil spill, and response may 

take years to acquire and analyze through the NRDA process, and impacts from the Deepwater Horizon

explosion and oil spill may be difficult or impossible to discern from other factors. It is not possible for 

BOEM to obtain this information within the timeline contemplated in the NEPA analysis of this 

Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable 

information, BOEM’s subject-matter experts have used available scientifically credible evidence in this 

analysis based upon accepted methods and approaches. However, BOEM believes that this incomplete or 

unavailable information regarding effects of the Deepwater Horizon explosion, oil spill, and response on 

birds (refer to Table 4-2 of the WPA 233/CPA 231 Supplemental EIS) would not likely be essential to a 

reasoned choice among alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS. Compared with non-OCS Program factors, 

such as habitat loss, collisions with non-OCS oil- and gas-related structures, disease, and other 

anthropogenic factors, which may result in billions of bird deaths per year, the incremental effect of a 
Description of the Environment and Impact Analysis 4-137

CPA proposed action is particularly small. Any information obtained from the Deepwater Horizon

explosion, oil spill, and response is unlikely to be so significant as to change the relative importance of 

non-OCS oil- and gas-related factors to bird populations (Table 4-7 of the 2012-2017 WPA/CPA 

Multisale EIS and Table 4-2 of the WPA 233/CPA 231 Supplemental EIS).

4.1.1.17.Gulf Sturgeon

BOEM has reexamined the analysis for Gulf sturgeon presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for Gulf 

sturgeon presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental 

EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated 

in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

A detailed description of Gulf sturgeon and the full analyses of the potential impacts of routine and 

accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.17 of the 2012-

2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.17 of the WPA 

233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the cumulative 

impacts is presented below, as well as any new information that has become available since those 

documents were published.

The following information is a summary of the resource description incorporated from the 2012-2017 

WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, and any new information that has 

become available since these documents were published. Gulf sturgeon were federally listed as 

threatened on September 30, 1991. A recovery plan was subsequently developed and critical habitat was 

designated on April 18, 2003. Threats to this anadromous species include overfishing and habitat 

destruction. Historically, Gulf sturgeon were commercially harvested, which dramatically declined 

population numbers. Subsequent dam construction intensified habitat loss and restricted access to historic 

spawning areas. Designated critical rivers and their associated estuaries include the Pearl, Pascagoula, 

Escambia, Yellow, Choctawhatchee, Apalachicola, and the Suwannee Rivers. Migration areas include 

the nearshore northern GOM from Lake Pontchartrain in Louisiana east to the Suwannee River in Florida. 

Although estimates are relatively imprecise, population trends have stabilized or shown slight increases in 

recent years at the riverine population scale (USDOI, FWS and USDOC, NMFS, 2009), suggesting that 

they may be making a slow comeback. Groups of Gulf sturgeon have been observed to remain for 

periods of time in foraging “holding areas,” or in deeper, darker, slower-moving areas of rivers or 

estuaries (Sulak et al., 2012). Natural or other accidental catastrophes have the potential to be detrimental 

to Gulf sturgeon populations and their habitats. 

Impacts of Routine and Accidental Events

A detailed impact analysis of the routine impacts of OCS activities associated with proposed CPA 

Lease Sales 235, 241, 247 on Gulf sturgeon can be found in Chapter 4.2.1.17.2 of the 2012-2017

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.17 of the WPA 233/CPA 

231 Supplemental EIS. Potential impacts to the threatened Gulf sturgeon and their designated critical 

habitat from routine activities associated with a CPA proposed action may occur from drilling and 

produced-water discharges, degradation of estuarine and marine water quality from infrastructure, 

dredging activities, vessel traffic, pipeline installation, and explosive platform removal. Designated Gulf 

sturgeon critical habitat is confined to State waters, and navigation channels are exempt from the critical 

habitat status. Most activities related to a CPA proposed action would occur in Federal waters (i.e., 

structure placement, drilling, removal, etc.). Though critical habitat may be impacted directly or 

indirectly, such impacts are expected to be negligible due to the distance of Gulf sturgeon habitat and life 

cycles from most activities related to a CPA proposed action.

Potential routine impacts on Gulf sturgeon and their designated critical habitat may occur from 

drilling and produced-water discharges, bottom degradation of estuarine and marine water quality by 

nonpoint runoff from estuarine OCS oil- and gas-related facilities, vessel traffic, pipeline installation, and 

explosive removal of structures. Because of the permitted discharge limits mandated and enforced in the 

Federal and State regulatory process, the dilution and low toxicity of this pollution is expected to result in 

negligible impacts of a CPA proposed action on Gulf sturgeon. Vessel traffic would generally only pose 
4-138 Central Planning Area Lease Sales 235, 241, and 247 EIS

a risk to Gulf sturgeon when the vessels are leaving and returning to port. Major navigation channels are 

excluded from critical habitat. Also, the Gulf sturgeon’s characteristics of bottom-feeding and general 

avoidance of disturbance make the probability of vessel strikes extremely remote. If pipeline is installed 

nearshore as a result of a CPA proposed action, regulatory permit requirements governing pipeline 

placement and dredging, as well as recent noninvasive techniques for locating pipelines, would result in a 

minimal impact to the Gulf sturgeon’s critical habitat. Explosive removal of structures as a result of a 

CPA proposed action would occur well offshore of the Gulf sturgeon’s critical habitat and the riverine, 

estuarine, and shallow Gulf habitats where sturgeon are generally located. There is no publicly available 

data indicating that sturgeons are using the deeper Gulf waters where most of the OCS activities occur. In 

general, the mud substrates found in the Gulf waters do not support the appropriate benthic food source 

for Gulf sturgeon. Due to regulations, mitigations, and the distance of routine activities from known Gulf 

sturgeon habitats, impacts from routine activities of a CPA proposed action would be expected to have 

negligible effects on Gulf sturgeon and their designated critical habitat.

Potential accidental impacts on Gulf sturgeon and the designated critical habitat may occur primarily 

from oil spills. A detailed impact analysis of the accidental impacts that may be associated with proposed 

CPA Lease Sales 235, 241 and 247 on Gulf sturgeon can be found in Chapter 4.2.1.17.3 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.17 of the WPA 233/CPA 

231 Supplemental EIS

Unusually low tidal events, increased wave energy, or the use of oil dispersants increases the risk of 

impact with bottom-feeding and bottom-dwelling fauna. For this reason, dispersants are not expected to 

be used with coastal spills. Winds and currents would also diminish the volume of a slick. For the 

Louisiana waters and beaches with a higher probability of oil-spill occurrence than the surrounding areas, 

the Mississippi River outflow would also serve to help break up a slick that might otherwise contact the 

area. Spreading of the slick would reduce the oil concentrations that would potentially impact the coastal 

Gulf sturgeon critical habitat.

The potential risk to sturgeon would result from either direct contact with oil spills (or the potential 

PAH’s introduced through the spill) or, in some cases, long-term exposure to produced water, or water 

associated with extraction process. The PAH’s could also reach the Gulf sturgeon through its diet of 

benthic invertebrates; PAH’s can accumulate in invertebrates (USDOI, GS, 2012a). The likelihood of 

Gulf sturgeon impacts in coastal waters as a result of OCS activity is reduced by both the distance from a 

potential spill or production area and the concentration of contaminants that actually reach the area of 

sturgeon activity. Except for oil spills in the nearshore environment, the Gulf sturgeon would be at 

greater risk of a PAH encounter from sources other than the OCS during the inland river migrations due 

to the industrial and farm waste introduced into these coastal rivers from the adjacent agricultural and 

urban land use. 

If there is contact with spilled oil, it could have detrimental physiological effects on Gulf sturgeon. In 

the rare event contact with oil occurs, this could cause nonlethal effects, including causing the fish to 

temporarily migrate from the affected area, irritation of gill epithelium, an increase of liver function in a 

few adults, and possibly interference with reproductive activity. The juvenile and subadult Gulf sturgeon, 

at a minimum, seasonally use the nearshore coastal waters and could potentially be at risk from both 

coastal and offshore spills. Due to the distance of the activity from shore and Gulf sturgeon critical 

habitat, there is a minimal risk of any oil coming in contact with Gulf sturgeon from an offshore spill. 

For a low-probability catastrophic spill, the proximity, type of oil, weather conditions, as well as the 

amount and location (distance offshore and water depth) of the dispersant treatment, may contribute to the 

severity of the spill’s impact to the sturgeon and its habitat (for more information regarding a lowprobability catastrophic spill, refer to Appendix B). 

Summary and Conclusion

BOEM has reexamined the analysis for Gulf sturgeon presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information provided 

above. Various Internet sources were examined to assess recent information regarding this resource that 

may be pertinent to a CPA proposed action. No new significant information was discovered that would 

alter the impact conclusion for these Gulf sturgeon presented in the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 
Description of the Environment and Impact Analysis 4-139

WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241 and 247.

The incremental contribution of a CPA proposed action to the cumulative impacts on Gulf sturgeon is 

negligible. This is because the effect of contact between lease sale-specific oil spills and Gulf sturgeon is 

expected to be sublethal, and regulations and mitigations decrease impacts from routine events. Other 

non-OCS oil- and gas-related activities, including storms and anthropogenic factors on habitat, are 

expected to result in more incremental and cumulative impacts to this species.

Cumulative Impacts

Background/Introduction 

This cumulative analysis summary considers the impacts of all past, present, and reasonably 

foreseeable future activities plus the contribution of a CPA proposed action that may adversely affect 

Gulf sturgeon within its range and critical habitat in the northern Gulf of Mexico. The cumulative 

impacts from routine OCS oil- and gas-related, impact-producing factors considered in this cumulative 

analysis include oil spills. Potential non-OCS oil- and gas-related impact-producing factors considered in 

this analysis include natural catastrophes, fishing, and other factors that can result in changes to habitats.

OCS Oil- and Gas-Related Impacts 

Gulf sturgeon could be impacted by oil spills resulting from a CPA proposed action. The effects on 

Gulf sturgeon from contact with spilled oil would be sublethal (Berg, 2006). Other potential impacts may 

occur from drilling and produced-water discharges, bottom degradation of estuarine and marine water 

quality by nonpoint runoff from estuarine OCS oil- and gas-related facilities, vessel traffic, pipeline 

installation, and explosive removal of structures. However, these impacts are expected to have negligible 

effects on Gulf sturgeon and their designated critical habitat, and will not be discussed as part of the 

cumulative impacts analysis.

Currently, there is little public data to ascertain the short-term and long-term effects of the Deepwater

Horizon explosion, oil spill, and response on the Gulf sturgeon or its critical habitat. It is known that its 

critical habitat was exposed to oil and could possibly have been repeatedly exposed to oil in some cases. 

Until rigorous analysis on the quantity, type, and toxicity of the oil and where its spatial subsurface 

location is performed, no assessment can be made to the benthic forage base of the Gulf sturgeon. In 

addition, the oil underwent evaporation and was quickly emulsified and diluted at the wellhead by 

dispersants, which made it readily available for biodegradation.

Because of the low probability of an offshore oil spill from a CPA proposed action occurring and 

contacting Gulf sturgeon critical habitat (≤4%; Figure 3-22 of the 2012-2017 WPA/CPA Multisale EIS), 

Gulf sturgeon contact with oil is expected to be minimal. The amount of oil projected to spill with a 

coastal spill is small, and it would have localized effects. For a more detailed analysis of low-probability 

catastrophic spills, refer to Appendix B. 

Non-OCS Oil- and Gas-Related Impacts

The Gulf sturgeon and its critical habitat can be cumulatively impacted by natural catastrophes, 

commercial fishing, State oil and gas activities, and other factors that can result in habitat changes. 

Recent climate trends and projections indicate more frequent and higher intensity storms, flooding, 

droughts, coastal erosion, and rising sea levels (Parry et al., 2007), all of which could impact Gulf 

sturgeon critical habitat, spawning areas and life history stages. Other naturally occurring events that can 

impact Gulf sturgeon may increase, such as the 1999 and 2005 red tides in Choctawhatchee Bay that 

resulted in sturgeon deaths (USDOI, FWS, 2000; State of Florida, Dept. of Environmental Protection, 

2012) or El Niño/La Niña events, which can cause fish to extend their range (USDOC, NOAA, 2013d). 

Deaths of adult sturgeon and potential habitat alterations are expected to occur from commercial fishing. 

Non-OCS oil- and gas-related accidental spills can happen, such as the 2008 industrial spill in the Pearl 

River in Louisiana that resulted in the mortality of juvenile and adult Gulf sturgeon (USDOI, FWS, 

2011b) and the February 2013 spill of wastewater from a water pollution control plant into the 

Withlacoochee River in Georgia (Schaefer, 2013). While these events have happened recently and there 
4-140 Central Planning Area Lease Sales 235, 241, and 247 EIS

is ongoing monitoring of the impacted areas, it is unknown how the related mortalities affect the Gulf 

sturgeon population.

BOEM does not regulate State oil and gas activities, which could result in potential cumulative 

impacts to Gulf sturgeon from oil spills, drilling and produced-water discharges, and bottom degradation 

from dredging and vessel traffic all near the coast. These activities generally occur in the marine and 

higher salinity estuarine coastal waters and not in the rivers and holding areas that the Gulf sturgeon 

frequent. Coastal land uses are not expected to affect Gulf sturgeon directly because of the protection set 

by critical habitat designation. However, upstream urbanization and commercial or residential 

development can adversely affect the water quality downstream and therefore can have potential 

cumulative impacts to Gulf sturgeon.

A CPA proposed action would not require dredging near natal rivers used as migratory routes to 

upstream spawning areas. While there could be a need for maintenance dredging not directly related to 

OCS oil- and gas-related activities in the nearshore waters, juvenile or adult sturgeon using these areas 

have the ability to avoid the regulated dredging activity.

On August 8, 2013, a notice of issuance of permits was published in the Federal Register for take of 

Gulf sturgeon for scientific research (Federal Register, 2013f). Substantial damage to Gulf sturgeon 

critical habitat is expected from natural catastrophes and inshore alteration activities, such as dam 

building or maintenance dredging. As a result, it is expected that the Gulf sturgeon would experience a 

decline in population sizes and a displacement from their current distribution that would last more than 

one generation. Non-OCS oil- and gas-related impacts are seen as the primary cumulative impacts on 

Gulf sturgeon, compared with a CPA proposed action, even in light of incomplete or unavailable 

information.

Summary and Conclusion

BOEM has reexamined the analysis for Gulf sturgeon presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information provided 

above. Various Internet sources were examined to assess recent information regarding this resource that 

may be pertinent to the CPA. No new significant information was discovered that would alter the impact 

conclusion for these Gulf sturgeon presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 

WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

The incremental contribution of a CPA proposed action to the cumulative impacts on Gulf sturgeon is 

negligible. This is because the effect of contact between lease sale-specific oil spills and Gulf sturgeon is 

expected to be sublethal, and regulations and mitigations decrease impacts from routine events. Other 

non-OCS oil- and gas-related activities, including storms and anthropogenic factors on habitat, are 

expected to result in more incremental and cumulative impacts to this species.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search was conducted for information published on Gulf sturgeon, and various Internet sources 

were examined to determine any recent information regarding this species. Sources investigated include 

BOEM, NMFS, FWS, USGS, IPCC, Florida Fish and Wildlife Conservation Commission, American 

Fisheries Society, State environmental agencies, current news events, and coastal universities. Other 

websites from scientific publication databases were checked for new information using general Internet 

searches based on major themes. No new significant information relevant to the above analysis was 

discovered since publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS.

The NRDA team has completed an assessment plan for nearshore resources following the Deepwater

Horizon explosion, oil spill, and response. The goals set forth are to characterize the extent and 

distribution of nearshore sediment oiling, to model exposure of organisms in the water column and 

benthos to hydrocarbons in nearshore sediments, and to evaluate and quantify injury to nearshore benthic 

organisms (USDOC, NOAA, 2012a). Workplans for this assessment can be found on NOAA’s website 

(USDOC, NOAA, 2013c). Analyses of available data are unavailable.
Description of the Environment and Impact Analysis 4-141

BOEM acknowledges that there remains incomplete or unavailable information on Gulf sturgeon, 

including potential impacts from the Deepwater Horizon explosion, oil spill, and response (and thus 

changes to the Gulf sturgeon baseline in the affected environment). This makes an understanding of the 

affected environment and impacts from a CPA proposed action less clear. BOEM concludes that the 

unavailable information from these events may be relevant to foreseeable significant adverse impacts to 

Gulf sturgeon. Nevertheless, BOEM believes that this incomplete or unavailable information regarding 

the effects of the Deepwater Horizon explosion, oil spill, and response on Gulf sturgeon may be essential 

to a reasoned choice among alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS. Relevant data on the status of Gulf sturgeon 

populations after the Deepwater Horizon explosion, oil spill, and response may take years to acquire and 

analyze, and impacts from the Deepwater Horizon explosion, oil spill, and response may be difficult or 

impossible to discern from other factors. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in the NEPA analysis of this Supplemental EIS, regardless 

of the cost or resources needed. In light of the incomplete or unavailable information, BOEM’s subjectmatter experts have used available scientifically credible evidence in this analysis (including data on 

related fish species) and applied this information based upon accepted scientific methods and approaches.

4.1.1.18.Fish Resources and Essential Fish Habitat

BOEM has reexamined the analysis for fish resources and essential fish habitat (EFH) presented in 

the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the 

additional information presented below. No new significant information was discovered that would alter 

the impact conclusion for fish resources and EFH presented in the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS.

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

CPA proposed action are presented in Chapter 4.2.1.18 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.18 of the WPA 233/CPA 231 Supplemental EIS. A 

CPA proposed action’s incremental contribution to the cumulative impacts is presented below. Any new 

information that has become available since those documents were published is presented below.

A detailed description of fish resources and EFH can be found in Chapter 4.2.1.18 and Appendix D of 

the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.18 of the 

WPA 233/CPA 231 Supplemental EIS. Also, EFH is discussed in the following chapters of this 

Supplemental EIS: water quality (Chapter 4.1.1.2); wetlands (Chapter 4.1.1.4); seagrass communities

(Chapter 4.1.1.5); live bottoms (Chapter 4.1.1.6); topographic features (Chapter 4.1.1.7); Sargassum

communities (Chapter 4.1.1.8); chemosynthetic deepwater benthic communities (Chapter 4.1.1.9); 

nonchemosynthetic deepwater benthic communities (Chapter 4.1.1.10); and soft bottom benthic 

communities (Chapter 4.1.1.11). 

Impacts of Routine and Accidental Events

Effects on fish resources and EFH from routine activities associated with a CPA proposed action 

could result from coastal environmental degradation, marine environmental degradation, pipeline 

trenching, and offshore discharges of drilling muds and produced waters. A detailed impact analysis of 

the routine impacts that may be associated with proposed CPA Lease Sales 235, 241, and 247 on fish 

resources and EFH can be found in Chapter 4.2.1.18.2 and Appendix D of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.18 of the WPA 233/CPA 231 

Supplemental EIS. Since the majority of fish species within the CPA are estuary dependent, any 

modification of the coastal environment resulting from a CPA proposed action has the potential to 

adversely affect EFH and fish resources through the loss of nursery habitat or functional impairment of 

existing habitat through decreased water quality (Chambers, 1992; Stroud, 1992). Although the potential 

exists, it is expected that any possible coastal and marine environmental degradation from a CPA 

proposed action would have little effect on fish resources or EFH.

With a CPA proposed action, BOEM projects no new coastal infrastructure with the exception of a 

potential new pipeline landfall and a potential new gas processing facility. Although the installation of 

pipelines has the potential to temporarily resuspend sediment in localized areas, this is expected to have a 

negligible impact. Depending on the sediment characteristics, sediment load, and duration of exposure, 
4-142 Central Planning Area Lease Sales 235, 241, and 247 EIS

impacts to commercially valuable species within a sediment plume can vary. Responses range in severity 

from no effect to mortality, but mobile species can avoid severe effects by limiting exposure. Sessile 

organisms and those with limited mobility may be exposed for longer durations, leading to increasingly 

severe impacts (e.g., increased respiratory rates, reduced feeding, and mortality). Regulations, 

mitigations, and practices reduce the undesirable effects on coastal habitats from dredging and other 

construction activities; permit requirements should ensure that pipeline routes avoid sensitive coastal 

habitat types. At the expected level of impact, the resultant influence on fish resources would be short 

term and localized, affecting only small portions of fish populations and selected areas of EFH. As a 

result, there would be little disturbance to fish resources or EFH.

The primary impacting sources to water quality in coastal waters are point-source and storm-water 

discharges from support facilities, vessel discharges, and nonpoint-source runoff. These activities are not 

only highly regulated but also localized and temporary in nature. The impacts to coastal water quality 

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

to shore of most routine activities and USEPA regulations that restrict discharges. Offshore water quality 

is affected temporarily and in a limited area by the discharge of produced water and the overboard 

discharge of drill muds. Maintenance dredging and canal widening in inshore areas causes only the 

temporary suspension of sediments. Negative impacts from most of these routine operations would 

require a short time for fish resources to recover. This is because of multiple life history and 

environmental factors such as fecundity or year-class recruitment through oceanographic circulation.

Offshore, many of the EFH’s are protected under the stipulations and regulations currently in place. 

Without these measures, there could be major negative impacts to topographic features and live bottoms. 

However, with routine impact-producing factors mitigated by BOEM through the Topographic Feature 

Stipulation and the Live Bottom (Pinnacle Trend and Low Relief) Stipulations, negative impacts are 

expected to be avoided. These stipulations establish a No Activity Zone around BOEM-protected 

topographic features, such as the Flower Gardens Banks, and NTL 2009-G39 and NTL 2009-G40 advise 

operators of BOEM’s distancing requirements for bottom disturbing activity from identified seafloor 

features (live bottoms, Pinnacles, topographic features, Potentially Sensitive Biologic Feature’s, and 

features capable of supporting high-density deepwater benthic communities). Additionally, hardsubstrate habitat provided by structure installation in areas where natural hard bottom is rare will tend to 

increase fish populations or attract fish populations. The removal of these structures will eliminate that 

habitat, except when decommissioned platforms are used as artificial reef material. This practice is 

expected to increase over time. A more detailed discussion of decommissioning and the impacts of these 

activities on marine fishes can be found in Chapters 3.1.1.10 and 4.2.1.19 of this Supplemental EIS,

respectively.

For these reasons, as well as the fact that Gulf of Mexico fish stocks have retained both diversity and 

relatively stable biomass throughout the years of offshore development and other disturbances, a CPA 

proposed action is expected to result in a minimal decrease in fish resources and/or standing stocks or in 

EFH. 

Accidental disturbances resulting from a CPA proposed action, including oil or chemical spills and 

blowouts, have the potential to adversely affect fish resources and EFH within the CPA. A detailed 

impact analysis of the accidental impacts that may be associated with proposed CPA Lease Sales 235, 

241, and 247 on fish resources and EFH can be found in Chapter 4.2.1.18.3 and Appendix D of the 2012-

2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.18 of the WPA 

233/CPA 231 Supplemental EIS.

If oil or chemical spills due to a CPA proposed action were to occur in open waters of the OCS 

proximate to mobile adult finfish, the effects would likely be nonfatal and the extent of damage would be 

reduced because adult fish have the ability to move away from a spill, to metabolize hydrocarbons, and to 

excrete both metabolites and parent compounds. Weathered crude oil has been shown in laboratory 

experiments and field research to cause a range of sublethal effects including malformation, genetic 

damage, and physiological impairment in different life history stages of different fish species (Carls et al., 

1999; Whitehead et al., 2011). Oil can be lethal to fish, especially in larval and egg stages, since early life 

stages of animals are usually more sensitive to environmental stress than adults (Moore and Dwyer, 

1974). Therefore, fish populations would primarily be affected if oil reaches the coastal and estuarine 

areas because many species reside in estuaries for at least part of their life cycle or are dependent on the 

nutrients exported from the estuaries to the shelf region. However, pelagic species may also be affected. 

Offshore spawning and nursery habitat supports several valuable species that could likewise be impacted 
Description of the Environment and Impact Analysis 4-143

by widespread contamination of the epipelagic region. However, due to natural variability in spawning 

success, recruitment, oceanographic conditions, and other factors, it is difficult to attribute specific causes 

to short-term shifts in stocks and research to date has been inconclusive with respect to the individual 

contributions of the many factors impacting these fishes (Rijnsdorp et al., 2009; Atlantic Bluefin Tuna 

SRT, 2011; Rooker et al., 2013). The probability of a spill impacting these nursery habitats is low. Much 

of the coastal northern Gulf of Mexico is a moderate- to high-energy environment; therefore, sediment 

transport and tidal stratification should reduce the chances for oil persisting in these areas if they are 

oiled. The extent to which a spill could impact offshore spawning and nursery habitat is highly dependent 

upon the time of year of the event.

The effect of oil spills that may be associated with a CPA proposed action on fish resources is 

expected to cause a minimal decrease in standing stocks of any population because most spill events 

would be small in scale and localized. Historically, there have been no oil spills of any size in the Gulf of 

Mexico that have had a long-term impact on fishery populations. Although many potential effects of the 

Deepwater Horizon explosion, oil spill, and response have been alleged, the actual effects are largely 

unknown and likely to remain so for several years, until more research is completed and the analyses 

become available. Recent analysis of early stage survival of fish species inhabiting seagrass nursery 

habitat from Chandeleur Islands, Louisiana, to St. Joseph Bay, Florida, pre- and post-Deepwater Horizon

oil spill show that immediate catastrophic losses of 2010 cohorts were largely avoided and that no shifts 

in species composition occurred following the spill (Fodrie and Heck, 2011). Analysis of the effects of a 

catastrophic oil spill can be found in Appendix B. The fish populations of the Gulf of Mexico have 

repeatedly proven to be resilient to large, annually occurring areas of anoxia, major hurricanes, and oil 

spills. Accidental events from a CPA proposed action are not expected to significantly affect fish 

populations or EFH in the Gulf of Mexico.

Summary and Conclusion

BOEM has reexamined the analysis for fish resources and EFH presented in the 2012-2017 

WPA/CPA Multisale EIS and the WPA 233/CPA 231 Supplemental EIS, based on the additional 

information provided above. Various printed and Internet sources (including NMFS’s databases, 

GMGFMC’s website, EBSCO, Elsevier, PLoS ONE, and BioOne) were examined to assess recent 

information regarding this resource that may be pertinent to the CPA. No new significant information 

was discovered that would alter the impact conclusion for the fish resources and EFH presented in the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. The analysis and 

potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 

231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

This cumulative analysis includes effects on fish resources and EFH’s as a result of the OCS Program 

(a CPA proposed action and past and future OCS lease sales), State oil and gas activity, coastal 

development, commercial and recreational fishing, and natural phenomena. For a detailed analysis of the 

cumulative impacts to EFH, refer to Appendix D of the 2012-2017 WPA/CPA Multisale EIS. An 

example of impact-producing factors considered in this analysis include cumulative onshore impacts on 

EFH’s, such as wetland loss as a result of human population expansion, as well as natural factors such as 

hurricane loss of wetlands, in addition to the cumulative impacts of OCS activities. Marine 

environmental degradation factors affecting water quality, such as hypoxia, are discussed in Chapter 

4.1.1.2, and they are summarized here.

Healthy fishery stocks depend on EFH’s, which are waters and substrate necessary to fish for 

spawning, breeding, feeding, and growth to maturity. Due to the wide variation of habitat requirements 

for all life history stages (as described in Appendix D of the 2012-2017 WPA/CPA Multisale EIS) for 

marine species, a large portion of the GOM is designated as EFH. The cumulative effects of OCS oiland gas- related and non-OCS oil- and gas-related factors on EFH’s can be found in the respective 

resource chapters: water quality (Chapter 4.1.1.2); wetlands (Chapter 4.1.1.4); seagrass communities

(Chapter 4.1.1.5); live bottom (pinnacle trend/low relief) (Chapter 4.1.1.6); topographic features

(Chapter 4.1.1.7); Sargassum communities (Chapter 4.1.1.8); chemosynthetic deepwater benthic 
4-144 Central Planning Area Lease Sales 235, 241, and 247 EIS

communities (Chapter 4.1.1.9); nonchemosynthetic deepwater benthic communities (Chapter 4.1.1.10); 

and soft bottom benthic communities (Chapter 4.1.1.11). The direct and/or indirect effects from 

cumulative OCS oil- and gas-related and non-OCS oil- and gas-related activities on fish resources are 

reanalyzed, while EFH’s are summarized in this chapter. 

OCS Oil- and Gas-Related Impacts 

Infrastructure projections reflect long-term industry trends, and existing oil and gas infrastructure is 

expected to be sufficient to handle development associated with a CPA proposed action. Any expansion 

of existing facilities or construction of new facilities would be closely scrutinized by State and Federal 

permitting agencies to ensure that potential impacts to estuarine habitats are avoided or mitigated. 

Secondary factors, such as vessel traffic supporting ongoing operations, will continue to have the greatest 

probability of producing impacts to fish resources and EFH and should receive greater attention. The 

present number of major navigation canals appears to be adequate for the OCS Program and most other 

developments. Some of these canals may be deepened or widened, and marine traffic causes erosion of 

adjacent wetlands. These secondary impacts of canals to wetlands will continue. The incremental 

contribution of a CPA proposed action would be a small part of the cumulative impacts to wetlands, 

seagrass communities, and coastal water quality; however, with new technologies and continual 

regulation and monitoring by COE, these activities will cause fewer effects.

Pipeline installation would cause sediment resuspension. Depending on the sediment characteristics, 

sediment load, and duration of exposure, impacts to commercially valuable species within a sediment 

plume can vary. Responses range in severity from no effect to mortality, but mobile species can avoid 

severe effects by limiting exposure. Sessile organisms and those with limited mobility may be exposed 

for longer durations, leading to increasingly severe impacts (e.g., increased respiratory rates, reduced 

feeding, and mortality). However, OCS activities resulting in sediment suspension are temporary and 

localized, and because of regulations, permitting processes, and protective stipulations, the OCS activities 

are expected to have minimal impact on fish resources and EFH. BOEM has conservatively estimated 

that 0-1 new pipelines will make landfall in the Gulf of Mexico, and a total of 30,428-69,749 km 

(18,907-43,340 mi) of pipeline could be installed in the GOM during the 40-year analysis period (Table 

3-3). Most oil and gas operations are assumed to use existing onshore structures and pipelines, which 

would have a small effect on coastal EFH and fish resources.

Topographic features in the GOM include the East and West Flower Garden Banks and Sonnier and 

Stetson Banks. The Topographic Features Stipulation, applied to appropriate leases and clarified in NTL 

2009-G39, would prevent most of the potential impacts on topographic features from offshore oil and gas 

bottom-disturbing activities. Also, the guidance provided in NTL 2009-G40 would distance bottomdisturbing activities from deepwater benthic communities such as chemosynthetic communities and 

deepwater corals. The projected total number of production structure installations resulting from OCS 

oil- and gas-related activities in the CPA and GOM during the next 40 years and for all water depths is 

1,180-1,640 (Table 3-4) and 1,435-2,026 (Table 3-3), respectively. Bottom disturbance from structure 

emplacement operations associated with a CPA proposed action would produce localized and temporary 

increases in suspended sediment loading. This would result in decreased water clarity and little 

reintroduction of pollutants. There is evidence that structure emplacements can act as fish-attracting 

devices and provide artificial habitat, resulting in the aggregation of migratory and reef fish species. It 

has also been reported that artificial habitat, such as that represented by some of the associated structures, 

can in some instances enhance production of fish (Stone et al., 1979; Carr and Hixon, 1997; Gallaway

et al., 2009; Shipp and Bortone, 2009).

It is estimated that 1,046-1,485 structures would be removed as a result of the OCS Program in the 

CPA during the next 40 years (Table 3-4) and that 1,279-1,837 structures would be removed as a result of 

the entire OCS Program during the next 40 years (Table 3-3). For more details on structure removal, 

please refer to Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf, 

Programmatic Environmental Assessment (USDOI, MMS, 2005). The removal of structures results in 

the loss of artificial habitat that was temporarily available for the life of particular OCS oil- and gasrelated activities, unless redeployed as artificial reef substrate. Redeployment of any structure as artificial 

reef substrate is contingent upon many factors, including operator interest and State and Federal approval 

of an application to participate in a State artificial reef program (Chapter 3.3.3.5). BOEM estimates that 

of the production structures removed in the next 40 years, 868-1,247 structures will be removed using 
Description of the Environment and Impact Analysis 4-145

explosives (Table 3-3). The potential for injury and mortality to fishes resulting from underwater blasts 

has been well documented (Hubbs and Rechnitzer, 1952; Ferguson, 1962; Teleki and Chamberlain, 1978; 

Govoni et al., 2008). Fish within the area of effect are subjected to a shock wave that expands radially, 

causing rapid contraction and over extension of the swim bladder, which may result in internal injury or 

mortality (Keevin and Hempen, 1997; Govoni et al., 2008). Invertebrates and fish with no swim bladder, 

or less well-developed swim bladders, are extremely resistant to underwater blasts. Other factors such as 

age, general health, water temperature, and reproductive condition may also influence mortality (Keevin 

and Hempen, 1997). It is expected that structure removals would have a major effect on fish resources

near the removal sites. However, these expected impacts to fish resources have been shown to be small 

overall and would not alter determinations of status for impacted species or result in changes in 

management strategies (Gitschlag et al., 2001). The Topographic Features Stipulation (NTL 2009-G39) 

and the guidelines provided in NTL 2009-G40 would decrease impacts on benthic communities from 

bottom-disturbing activities such as anchoring and structure emplacement and removal.

Localized, minor degradation of coastal water quality is expected from a CPA proposed action within 

the immediate vicinity of the waterbodies proximate to the proposed service bases, commercial wastedisposal facilities, and gas processing facilities as a result of routine effluent discharges and runoff 

(Chapter 4.1.1.2.1). The degradation of water quality can cause increased physiological stress in marine 

organisms or can result in hypoxia, causing mobile species to avoid or leave low quality habitat. Because 

the input of effluent, runoff, and nutrients from a CPA proposed action is very limited, the incremental 

contribution of a CPA proposed action would be a very small part of the cumulative impacts to coastal 

water quality. A CPA proposed action would add slightly to the overall offshore water quality 

degradation through the disposal of offshore operational wastes and sedimentation/sediment resuspension 

(Chapter 4.1.1.2.2). Offshore vessel traffic and OCS operations would contribute in a small way to 

regional degradation of offshore waters through different waste discharges and spills. 

Drilling mud discharges contain chemicals toxic to marine fishes; however, this is only at 

concentrations four or five orders of magnitude higher than those found more than a few meters from the 

discharge point. This is because offshore discharges of drilling mud dilute to near background levels 

within 1,000 m (3,280 ft) of the discharge point. Biomagnification of pollutants such as mercury are 

often associated with drilling discharges; however, the bioavailability of trace concentrations of mercury 

in discharged drilling mud has not been demonstrated. A recent study has concluded that platforms do 

not contribute to higher mercury levels in marine organisms (Sluis et al., 2013). Another study suggests 

that mercury in sediment from drilling platforms is not in a bioavailable form (Trefry et al., 2003). 

Because the deposition of drilling mud is limited in space around the platform and because the mercury 

contained in the mud is not in bioavailable form, the discharge of drilling mud around platforms is 

expected to have a negligible effect on fish at a population level.

Produced-water discharges contain components and properties potentially detrimental to fish 

resources. These include petroleum hydrocarbons, trace metals, radionuclides, and brine. Limited 

petroleum concentrations and metal contamination of sediments and the upper water column would occur 

out to several hundred meters or feet downcurrent from the discharge point. Because produced waters are 

limited in space and are quickly diluted, the effects of produced waters on fish populations in the OCS 

environment are expected to be small. Fish populations inhabiting offshore live bottoms would similarly 

not be impacted by produced waters because they are released and disperse near the surface and because 

the deposition of drilling mud is limited because of current mitigation. Offshore discharges and 

subsequent changes to marine water quality are also regulated by the U.S. Environmental Protection 

Agency’s NPDES permits.

In the unlikely event of an offshore spill, the biological resources of hard/topographic features are 

expected to remain unharmed as the spilled substances would likely reach the seafloor in minute 

concentrations. These minute quantities may cause very short-term sublethal effects such as reduced 

feeding and photosynthesis or altered behavior (Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 

1984). A more detailed analysis of the potential impacts to topographic features from an offshore spill 

can be found in Chapter 4.1.1.7. 

Surface oil spills would have the greatest chance of impacting high-relief topographic features located 

in depths <20 m (65 ft; mostly sublethal impacts). A comprehensive survey of all low-relief live bottoms

in the CPA has yet to be conducted, but all major topographic features are well described (Chapter 

4.2.1.7.1 of the 2012-2017 WPA/CPA Multisale EIS). Only three high-relief features in the Gulf rise to 
4-146 Central Planning Area Lease Sales 235, 241, and 247 EIS

water depths shallower than 20 m (65 ft). These are the East Flower Garden Bank (16 m; 52 ft), Stetson 

Bank (17 m; 55 ft), and Sonnier Bank (17 m; 55 ft).

Subsurface blowouts of both oil and natural gas wells and subsurface spills (pipeline spills) have the 

potential to adversely affect fishery resources and could cause localized, sublethal (short-term, 

physiological changes such as reduced feeding or increased respiration) impacts on the biologically 

sensitive underwater features, areas, and deepwater benthic communities. The range of potential impacts 

and most likely effects are discussed in the following chapters: live bottoms (Pinnacle Trend and low 

relief) (Chapter 4.1.1.6); topographic features (Chapter 4.1.1.7); chemosynthetic deepwater benthic 

communities (Chapter 4.1.1.9); nonchemosynthetic deepwater benthic communities (Chapter 4.1.1.10); 

and soft bottom benthic communities (Chapter 4.1.1.11). However, these events are rare and, should one 

occur, protective lease stipulations mitigate the potential impacts on the live bottoms of the entire activity 

area, so community-wide impacts should not occur. Sandy sediments resuspended as a result of a 

blowout would be quickly redeposited within 400 m (1,312 ft) of the blowout site, and finer sediments 

would be widely dispersed and redeposited within a few thousand meters over a period of 30 days or 

longer. Effects on fish resources as a result of sediment resuspension due to a blowout, though longer in 

duration, would be similar to those described for other bottom-disturbing activities. These events are 

expected to have a negligible impact on fish populations.

Oil spills that contact coastal bays, estuaries, and offshore waters (each are EFH) when pelagic eggs 

and larvae are present have the greatest potential to affect fish resources. Early life stages of animals are 

usually more sensitive to environmental stress than adults (Moore and Dwyer, 1974), and oil can be lethal 

to fish, especially in larval and egg stages. Weathered crude oil has been shown in laboratory 

experiments to cause malformation, genetic damage, and even mortality at low levels in fish embryos of 

Pacific herring (Carls et al., 1998). However, the results of recent studies of fish resources (species and 

communities) indicate impacts resulting from the Deepwater Horizon oil spill have been largely 

indistinguishable from natural fluctuations or variability due to other anthropogenic activities (Atlantic 

Bluefin Tuna Status Review Team, 2011; Fodrie and Heck, 2011; Soniat et al., 2011; Carmichael et al., 

2012; Moody et al., 2013; Rooker et al., 2013). Although there is a large body of information being 

developed through the NRDA process that is not yet available, these early results are not indicative of 

significant population-level responses. If spills were to occur in coastal bays, estuaries, or waters of the 

OCS proximate to mobile adult finfish or shellfish, the effects would likely be sublethal and the extent of 

damage would be reduced due to the capability of adult fish and shellfish to avoid a spill, to metabolize 

hydrocarbons, and to excrete both metabolites and parent compounds. For eggs and larvae contacted by 

spilled diesel, the effect is expected to be lethal.

Contamination from oil and hazardous substance spills should be primarily localized and not long 

term enough to preclude designated uses of the waters. For example, a large coastal spill that could occur 

from OCS oil- and gas-related activity in the CPA would likely originate near terminal locations, which 

are most numerous in the coastal zone of Louisiana (Figure 3-5 of the 2012-2017 Multisale EIS). As a 

result of spill response, containment, and recovery efforts, most of the inland spills’ contents are expected 

to be recovered and what is not recovered would affect a small area and dissipate rapidly. The 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS analyzed the effect for oil spills

≥1,000 bbl if a spill was to occur due to a CPA proposed action. The probabilities of that spill contacting 

different EFH after 10 days and a spill (≥ 1,000 bbl) contacting an EFH after 30 days are presented in the 

following chapters of the 2012-2017 WPA/CPA Multisale EIS: water quality (Chapters 4.2.1.2.1.3 and 

4.2.1.2.2.3); wetlands (Chapter 4.2.1.4.3); seagrass communities (Chapter 4.2.1.5.3); live bottoms

(Chapters 4.2.1.6.1.3 and 4.2.1.6.2.3); topographic features (Chapter 4.2.1.7.3); Sargassum communities 

(Chapter 4.2.1.8.3); chemosynthetic deepwater benthic communities (Chapter 4.2.1.9.3); 

nonchemosynthetic deepwater benthic communities (Chapter 4.2.1.10.3); and soft bottom benthic 

communities (Chapters 4.2.1.11.3).

Loss of well control and resultant blowouts and pipeline spills seldom occur on the Gulf of Mexico 

OCS. Estimated occurrences and probabilities of these events for all water depths in the OCS are 

presented in Tables 3-19 and 3-20 of the 2012-2017 WPA/CPA Multisale EIS.

Subsurface blowouts, such as the Deepwater Horizon explosion, that include both oil and natural gas 

have the potential to affect fish populations, particularly eggs, larvae, and juveniles. The specific effects 

of this type of spill on individual fish populations in the GOM are currently being investigated. Few, if 

any, definitive results have been obtained at this time. Spills from this type of a blowout have a low 

probability of occurring. The cumulative impact on EFH and fish populations is, therefore, not 
Description of the Environment and Impact Analysis 4-147

anticipated to be large as a result of a CPA proposed action. For a more detailed analysis of lowprobability catastrophic spills, refer to Appendix B. 

Non-OCS Oil- and Gas-Related Impacts

Much of coastal wetland loss is a result of agricultural, commercial, and residential development; 

inshore oil and gas extraction; and river modification. The conversion of wetlands for agricultural, 

residential, and commercial uses has been substantial. The trend is projected to continue into the future, 

although at a slower rate because of regulatory pressures. The most serious impact to EFH is the 

cumulative effects on wetlands that are occurring at an ever-increasing rate as the Gulf Coast States’ 

human populations increase and with relative sea-level rise (GMFMC, 1998). Residential, commercial, 

and industrial developments are directly impacting EFH by dredging and filling coastal areas or by 

affecting the watersheds. Also, the conversion of wetland habitat into open water is projected to continue 

in the foreseeable future. This is actually a shift in EFH from important nursery habitat to open-water 

habitat. State oil and gas activities are projected to have greater and more frequent adverse impacts on 

wetlands than would the OCS Program offshore activities because of their proximity to the shore. Other 

factors that impact coastal wetlands include marsh burning and marsh-buggy traffic. Tracks left by marsh 

buggies open new routes of water flow through relatively unbroken marsh and can persist for up to 

30 years, thereby inducing and accelerating erosion and sediment export. The Federal and State 

governments are also funding research and coastal restoration projects; however, it may take decades of 

monitoring to ascertain the long-term feasibility of these coastal restoration efforts.

Canal dredging primarily accommodates commercial, residential, and recreational development. 

Increased population and commercial pressures on the Gulf Coast are also causing the expansion of ports 

and marinas. Where new channels are dredged, wetlands would be adversely impacted by the channel, 

the disposal of dredged materials, and the development that it attracts. The continuing erosion of 

waterways maintained by COE is projected to adversely impact the productivity of wetlands along 

channel banks. Also, increased turbidity from dredging operations projected to continue within the 

coastal zone constitutes another considerable type of pollution. However, continual advances in 

technologies and mitigation required by COE in permits decrease many adverse effects on coastal habitats 

and water quality from dredging and related activities.

Estuarine water quality degradation is largely due to urban and agricultural runoff. The coastal 

waters of the CPA are expected to continue to experience nutrient enrichment, low-dissolved oxygen, and 

toxin and pesticide contamination, resulting in the loss of both commercial and recreational uses of the 

affected waters. Fish kills, shellfish-ground closures, and restricted swimming areas will likely increase 

in numbers over the next 30-40 years based on impacts from the non-OCS oil- and gas-related impacts 

described above. The degradation of water quality is expected to continue due to contamination by pointand nonpoint-source discharges due to eutrophication of waterbodies, primarily due to runoff and 

hydrologic modifications. However, stringent water quality standards are monitored and enforced by 

USEPA and USCG. Municipal, agricultural, and industrial coastal discharges and land runoff would 

impact the health of marine waters. As the assimilative capacity of coastal waters is exceeded, there will 

be a subsequent, gradual movement of the area of degraded waters farther offshore over time. This 

degradation will cause short-term loss of the designated uses of some shallow offshore waters due to 

hypoxia and red or brown tide impacts and to the levels of contaminants in some fish, thereby exceeding 

human health standards. Coastal sources are assumed to exceed all other sources, with the Mississippi 

River continuing to be the major source of contaminants to the north-central Gulf area.

Commercial fishing activities that could impact topographic features would include trawl fishing and 

trap fishing. With the exception of localized harvesting techniques, most wild-caught shrimp are 

collected using bottom trawls—nets towed along the seafloor—held apart with heavy bottom sled devices 

called “doors” made of wood or steel. In addition to the nonselective nature of bottom trawls, they can be 

potentially damaging to the bottom community as they drag. Trawls pulled over the bottom disrupt the 

communities that live on and just below the surface and also increase turbidity of the water (GMFMC, 

1998).

Throughout the Gulf Coast, commercial trap fishing is used for the capture of reef fish, and 

commercial and recreational trap fishing is used for the capture of spiny lobster, stone crab, and blue crab. 

Reef fish traps are primarily constructed of vinyl-covered wire mesh and include a tapered funnel where 

the fish can enter but not escape. Traps can potentially damage the bottom community, depending on 
4-148 Central Planning Area Lease Sales 235, 241, and 247 EIS

where they are placed. If they are deployed and retrieved from coral habitats or live bottoms, they can 

damage the corals and other attached invertebrates on the reef. Seagrasses can also be broken or 

destroyed by the placement and retrieval of traps in shallow environments (GMFMC, 1998).

Overfishing (commercial and recreational) has been determined to be a major factor in four 

populations of reef fish in the Gulf of Mexico. According to the NMFS Status of Stocks 2012 report, 

Gulf of Mexico overfished species included gag (Mycteroperca microlepis), greater amberjack (Seriola 

dumerili), red snapper (Lutjanus campechanus), and gray triggerfish (Balistes capriscus); all but red 

snapper were still subject to overfishing (USDOC, NMFS, 2013d). These species are reef fish that range 

throughout the Gulf and are discussed in Chapters 4.2.1.18.1 and 4.2.1.19.1 and Appendix D of the 2012-

2017 WPA/CPA Multisale EIS and Chapters 4.1.1.16 and 4.1.1.17 of the WPA 233/CPA 231 

Supplemental EIS. Many of the important species harvested from the Gulf of Mexico are believed to 

have been overfished, but managers are making progress in rebuilding or sustainably managing those 

stocks with known status (USDOC, NMFS, 2013d). However, there remain stocks with an unknown 

status and, while these represent a smaller fraction of commercial and recreational landings, it is possible 

that some are subject to overfishing and that continued fishing at the present levels may result in declines 

of fish resource populations and the eventual failure of certain fisheries. It is expected that overfishing of 

targeted species and trawl fishery bycatch will adversely affect fish resources. The impact of overfishing 

on fish resources is expected to cause a measurable decrease in populations, although the Gulf of Mexico 

Fisheries Management Council (GMFMC) has taken action to avoid the exploitation of overfished species 

in the form of increased regulations. The Magnuson-Stevens Fishery Conservation and Management Act 

and its amendments address sustainable fisheries and set guidelines for protecting marine resources and 

habitat from fishing- and nonfishing-related activities. Under this Act, fisheries management plans, 

including limits on catch and fishing seasons, are developed and proposed by the regional fisheries 

management councils for approval and implementation by NMFS. State agencies regulate inshore fishing 

seasons and limits.

Invasive species such as lionfish are a threat to commercially important species native to the Gulf of 

Mexico. Lionfish have been observed on natural bottom, reefs, and artificial structures across the 

northern Gulf of Mexico. These fish are voracious predators and have the potential to displace native 

species through competition for food sources and habitat space.

Finally, some natural phenomena can impact fish resources and EFH’s. Nearshore habitat can be 

affected through events such as severe storms and floods. These events can accelerate wetland loss or 

damage oyster reef habitat. Offshore resources such as biologically sensitive underwater features may be 

damaged or buried by events like storms or turbidity flows, potentially affecting fish resources. 

Additionally, variability in spawning success and juvenile survival directly affect Gulf of Mexico fish 

populations. These natural phenomena are all continual, integral elements of the ecosystem, and impacts 

attributed to these events are often exacerbated by anthropogenic activities.

Summary and Conclusion 

In summary, there are widespread anthropogenic and natural factors that impact EFH and fish 

populations in the Gulf of Mexico. Many State and Federal agencies have shared or sole responsibility 

for implementing the laws and regulations within their jurisdiction that ensure coastal development and 

industrial operations are performed responsibly and that potential impacts are avoided or properly 

mitigated. Despite this concerted effort, incremental, accidental and natural or unavoidable impacts 

occur. However, the forecasted activities associated with a proposed CPA action, planned, executed and 

mitigated in accordance with applicable regulations and guidelines, are expected to contribute minimally 

to the cumulative impact on fish resources and EFH.

As noted in Chapter 4.1.1.18 of this Supplemental EIS, Chapter 4.2.1.18.1 of the 2012-2017 

WPA/CPA Multisale EIS, and Chapter 4.2.1.18 of the WPA 233/CPA 231 Supplemental EIS, most of the 

Gulf of Mexico is designated as EFH and encompasses many different types of habitats and resources, 

which are described in this Supplemental EIS. The extent of impacts from the Deepwater Horizon

explosion, oil spill, and response to fish resources and EFH remains unclear at this time. This 

information is being developed through the NRDA process, data are still incoming and have not been 

made publicly available, and it is expected to be years before the information is available. No evidence of 

significant impacts to fisheries populations in the Gulf of Mexico have been shown to date.
Description of the Environment and Impact Analysis 4-149

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources and scientific journals was conducted to determine the 

availability of recent information (including NMFS’s databases, GMFMC’s website, Science Direct, 

EBSCO, Elsevier, PLoS ONE, JSTOR, and BioOne). No new significant scientific information has been 

identified as relevant to this analysis since the publication of the 2012-2017 WPA/CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS.

The severity and the duration of the effects of the Deepwater Horizon explosion, oil spill, and 

response on the fish assemblages and fisheries of the Gulf of Mexico are largely speculative at this time. 

No evidence of significant impacts to fish populations in the Gulf of Mexico have been shown to date. It 

is also difficult to gather reliable population information on all species, including highly migratory 

species, and to distinguish between population fluctuations due to the spill as opposed to other, naturally 

occurring environmental factors. Credible scientific information that is available on the impacts to the 

species has been applied using accepted methodologies. In any event, although some information is 

currently unavailable, it is not essential to a reasoned choice among alternatives for the reasons stated in 

this Supplemental EIS and in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. Nevertheless, information on the effects of the Deepwater Horizon explosion, oil 

spill, and response on fish resources and EFH is incomplete at this time and may take years to obtain and 

analyze. This information will be developed through the NRDA process, is not expected to be complete 

or released to the public for years, and will certainly not be available within the timeline contemplated in 

the NEPA analysis of this Supplemental EIS. Regardless of cost, it is not within BOEM’s ability to 

obtain this information from the ongoing NRDA process. This information may be relevant to reasonably 

foreseeable significant impacts, and BOEM cannot definitively state at the present time whether this 

information may be essential to a reasoned choice among alternatives. BOEM’s subject-matter experts, 

however, have used the scientifically credible information that is available and applied it using accepted 

scientific methodologies.

4.1.1.19.Commercial Fisheries

BOEM has reexamined the analysis for commercial fisheries presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

commercial fisheries presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts discussed in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 

247.

A detailed description of commercial fisheries and the full analyses of the potential impacts of routine 

activities and accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.19 

of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.19 of 

the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the 

cumulative impacts is presented below. Any new information that has become available since those 

documents were published is presented below.

Impacts of Routine and Accidental Events

The potential routine impact-producing factors on commercial fisheries in the CPA are seismic 

surveys and operational noise, drilling, platform emplacement, platform removal, pipeline installation, 

waste discharge, channel dredging and oil spills. Analysis of the routine impacts of OCS activities 

associated with a CPA proposed action on commercial fisheries can be found in Chapter 4.2.1.19.2 of the 

2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.19 of the 

WPA 233/CPA 231 Supplemental EIS.

Routine activities such as seismic surveys, platform operation, and vessel traffic produce noise of 

varying intensity and duration; a description of this factor can be found in Chapter 3.1.1.2.1 of this 

Supplemental EIS, with a more detailed description provided in Chapters 3.1.1.2 and 3.1.1.6 of the 2012-

2017 WPA/CPA Multisale EIS. A CPA proposed action, throughout the 40-year life cycle, is estimated 
4-150 Central Planning Area Lease Sales 235, 241, and 247 EIS

to result in numerous seismic survey activities. Studies have shown that air guns can produce behavioral 

responses in fishes, possibly even resulting in species- or gear-specific effects on catch rate (Popper and 

Hastings, 2009; Fewtrell and McCauley, 2012; Lokkeborg et al., 2012). However, there is insufficient 

data to consistently predict that responses and important variables, such as the duration of exposure and 

repeated exposure, have not been fully addressed. Seismic surveys are cyclical, temporary, localized 

events, and they are not expected to have a significant impact on commercial fisheries. 

Exploratory drilling rigs cause temporary interference to commercial fishing, lasting approximately 

30-150 days, and emplaced structures represent a semipermanent obstruction to some forms of 

commercial fishing, trawling and longlining in particular. BOEM estimates that 31-60 platforms would 

be installed in waters 200 m (656 ft) or less in depth as the result of a CPA proposed action. At these 

depths, the structures would yield approximately 62-120 ha (310-600 ac) unavailable to trawling. 

Longline fishing is performed in water depths greater than 100 m (328 ft) and usually beyond 300 m 

(984 ft). BOEM estimates that 7-13 platforms will be installed in this depth range, presenting a minor 

space-use conflict. Concerns that an areal comparison insufficiently considers geological formations and 

other features that constitute “high-quality” fishing grounds are not justified since the stipulations and 

regulations currently in place protect these habitats from being impacted by OCS activities. In addition, 

the current paradigm posits these structures act as both fish-attracting and production-enhancing devices, 

depending upon the species (Carr and Hixon, 1997; Gallaway et al., 2009; Shipp and Bortone, 2009). 

The resultant assemblages frequently include commercially valuable fishes, such as tunas (Thunnus spp.), 

red snapper (Lutjanus campechanus) and wahoo (Acanthocybium solanderi), and attract fishermen 

targeting these species. However, OCS platforms and supporting infrastructure do pose a hazard to 

commercial fishing vessels and gear. The Fishermen’s Contingency Fund was created to compensate 

fishermen for economic and property losses as a result of oil and gas industry activities on the OCS 

(Sharp and Sumaila, 2009; USDOC, NMFS, 2013e). According to NMFS, claims were approved for 

$188,168 in FY 2010, $126,608 in FY 2011 and $63,588 in 2012.

The most commonly discharged offshore wastes are drilling mud and produced water. Drill mud 

contains metals such as mercury and cadmium, which are toxic to fishery resources, and produced water 

commonly contains brine, trace metals, hydrocarbons, organic acids, and radionuclides. Studies of 

drilling mud and produced-water discharges from platforms show that the plume disperses rapidly in both 

cases and does not pose a threat to commercial fisheries. Because of concern about bioaccumulation of 

mercury in some fishes (Oken et al., 2012), the Gulf of Mexico in general, and areas with OCS oil and gas 

infrastructure in particular, have been the subject of several studies on mercury concentrations in 

sediment and uptake of mercury associated with drilling. As of the writing of this document, the latest 

study to investigate potential relationships between mercury concentrations in fish tissues and habitat 

compared fish caught near platforms with those caught at non-platform habitat. The researchers found no 

significant difference in the total mercury concentrations in tissue samples taken from fish captured at 

either habitat type (Sluis et al., 2013). This study supports earlier research, which resulted in similar 

findings (Trefry et al., 2003; Lowery and Garrett, 2005).

Pipeline trenching, navigation channel dredging, and canal construction resuspend sediments, but 

they are expected to cause negligible impacts and would not deleteriously affect overall CPA commercial 

fishing activities. Depending on the sediment characteristics, sediment load, and duration of exposure, 

impacts to commercially valuable species within a sediment plume can vary. Responses range in severity 

from no effect to mortality, but mobile species can avoid severe effects by limiting exposure. Sessile 

organisms and those with limited mobility may be exposed for longer durations, leading to increasingly 

severe impacts (e.g., increased respiratory rates, reduced feeding, and mortality). Regulations, 

mitigations, and permit requirements should ensure that impacts to habitat are avoided or minimized. 

Platform emplacement would cause displacement of commercial fishing while operations are ongoing, 

and explosive removal of platforms will cause temporary displacement of commercial fishing activities 

and localized fish mortality. These effects are limited to a small percentage of the area fished and will not 

significantly impact commercial fishing or fish stocks in the CPA. Furthermore, some platforms will be 

decommissioned using nonexplosive methods and redeployed as artificial reef substrate. For more 

information, refer to Chapter 3.3.3.5. 

Accidental disturbances resulting from a CPA proposed action, including oil spills and blowouts, 

have the potential to result in temporary closures and/or direct impacts to fish populations, both inshore 

and offshore, thereby affecting commercial fisheries within the CPA. Additional impact analysis of 

accidental events that may be associated with proposed CPA Lease Sales 235, 241, and 247 on 
Description of the Environment and Impact Analysis 4-151

commercial fisheries can be found in Chapter 4.2.1.19.3 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.19 of the WPA 233/CPA 231 Supplemental EIS.

In the event of an oil spill or blowout (refer to Chapter 3.2.1 and Appendix B for a detailed risk 

analysis), fish populations will primarily be impacted if the oil reaches the productive shelf and estuarine 

areas. Although there is a risk of spills occurring in coastal waters (0-5.6 km; 0-3.5 mi; 0-3.0 nmi), the 

majority of these would be small and unlikely to impact commercial fisheries. Most of these incidents 

would occur at or near pipeline terminals or shore bases and are expected to only temporarily affect a 

localized area. The probability of an offshore spill impacting these nearshore environments is low, and 

oil would generally be volatilized or dispersed by currents in the offshore environment. The most 

damaging oil spills to commercial fishery harvests would be those reaching the productive coastal waters 

or estuaries. However, while short-term negative impacts may be greatest on those populations that are 

short-lived and harvested annually, such as crabs and shrimp, or those populations that are sessile, such as 

oysters, these species have evolved to cope with high mortality through large population growth potential 

and should not suffer long-term population effects. Longer-lived species such as snapper and grouper 

have more resilience because these populations consist of multiple year classes that can breed, and the 

failure of any one year-class does not necessarily threaten the survival of the population. Historically, 

spills of sufficient magnitude to potentially and broadly affect these sensitive areas have a very low 

probability of occurrence.

Fisheries closures may result from a large spill event. When closures occur, they are generally small 

and short lived. Most fishermen should be able to avoid these closures, causing only localized economic 

impacts. Large-scale closures are rare, but can inflict more widespread negative economic impacts on 

commercial fishermen due to inability to fish and decreased marketability of their catch. These closures 

may also relieve fishing pressure and allow fisheries populations to increase the following year.

The potential impacts due to accidental events (i.e., a well blowout or an oil spill) from a CPA 

proposed action are anticipated to be minimal. The most typical events are small and of short duration, 

and the effects are so localized that fish may avoid the area adversely impacted.

Summary and Conclusion

The activities associated with a CPA proposed action would cause short-term, localized disturbances 

to fishes in the vicinity (e.g., acoustic surveys and resuspension of sediments) or highly localized fish 

mortality (e.g., explosive severance activities). However, these impacts do not extend to population-level 

effects due to the limited spatial and temporal nature of routine activities. Although structure 

emplacement represents a long-term, space-use conflict, the area excluded is insignificant in comparison 

with the area available for some commercial fishers. Furthermore, historical landings data do not support 

an argument for regional negative impacts to commercial fisheries through either stock reduction or 

access limitations. While accidental disturbances have the potential to result in broader impacts to 

commercial fisheries through closures or juvenile mortality, these are very low-probability events.

In conclusion, impacts to commercial fisheries due to routine activities or accidental events resulting 

from a CPA proposed action are expected to be minimal. No new information was discovered that would 

alter the conclusion for commercial fisheries presented in the 2012-2017 WPA/CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS.

Cumulative Impacts

Background/Introduction 

This cumulative analysis considers activities that have occurred, are currently occurring, and could 

occur and adversely affect commercial fishing for the years 2012-2051. These activities include the 

effects of the OCS Program (proposed action and prior and future OCS sales), State oil and gas activity, 

oil transport by tankers, natural phenomena, and commercial and recreational fishing. 

The potential impact-producing factors considered in the cumulative analysis include seismic surveys 

and operational noise, drilling, platform emplacement, platform removal, pipeline installation, waste 

discharge, channel dredging, oil spills, State oil and gas activity, coastal commercial and residential 

development, commercial and recreational fishing techniques and practices, and natural phenomena.
4-152 Central Planning Area Lease Sales 235, 241, and 247 EIS

OCS Oil- and Gas-Related Impacts 

Seismic surveys are used in both shallow- and deepwater areas of the Gulf of Mexico. Seismic 

surveys and operational noise have been shown to produce behavioral responses in fishes, but the results 

of studies are inconclusive and specific behaviors or effects on catch rate cannot be predicted. 

Furthermore, there is evidence that repeated episodes may elicit reduced or different responses from fish 

(Fewtrell and McCauley, 2012). Seismic surveys also cause space-use conflicts but are limited in time 

and space. Although fishermen may be precluded from an area for several days, this should not 

significantly affect the annual landings or the value of landings for commercial fisheries. Targeted 

species are usually found in many adjacent locations, and commercial fishermen typically do not fish only 

one locale.

Production facilities also compete with commercial fishing interests for physical space in the open 

ocean, and associated underwater OCS obstructions can pose hazards to fishing gear. BOEM estimates 

there will be 1,180-1,640 production structures installed in the CPA over the next 40 years (Table 3-4). 

Each production platform excludes a small area from the resources available for most commercial fishing. 

However, even the cumulative impact of these exclusions is small in comparison to the total area 

available for commercial fishing in the CPA. Concerns that an areal comparison insufficiently considers 

geological formations and other features that constitute “high-quality” fishing grounds are not justified 

since the stipulations and regulations currently in place protect these habitats from being impacted by 

OCS activities. In addition, the current paradigm posits these structures act as both fish-attracting and 

production-enhancing devices, depending upon the species (Carr and Hixon, 1997; Gallaway et al., 2009; 

Shipp and Bortone, 2009). As such, it is expected that these benefits, over the 40-year analysis period, 

will outweigh localized disturbances and fish mortality resulting from exploration, installation, and 

decommissioning activities. The impact of a CPA proposed action on commercial fisheries is anticipated 

to be small.

Offsetting the projected installation of facilities is the removal of existing platforms that have reached 

the end of their useful life. Approximately 1,046-1,485 production structures are expected to be removed 

from the CPA over the next 40 years (Table 3-4). Although each removal frees an area for commercial 

fishing, it also removes artificial hard substrate. Since BSEE encourages the reuse of obsolete oil and gas 

structures as artificial reefs, a lessee may be granted a departure from the requirement to remove a 

platform if the necessary conditions are met (BSEE Interim Policy Document 2013-07). In these 

instances, decommissioned structures may be used in State-managed Rigs-to-Reefs programs, and 

accepted structures would continue to serve as artificial reef substrate. It is estimated that 60 percent of 

the projected removals will involve explosive severance activities. These removal operations result in 

localized mortality of fishes. A study of explosive removals found that associated mortality for three 

commercially important fishes did not significantly alter projected stocks (Gitschlag et al., 2000). To 

account for inherent variations in species composition and abundance among platforms (e.g., Stanley and 

Wilson, 1997; Gitschlag et al., 2000; Stanley and Wilson, 2000; Wilson et al., 2003), mortality estimates 

were doubled and stock estimates were recalculated. Although Gitschlag et al. (2000) was limited and 

cannot be directly applied to all species or habitats, it is reasonable to assume that other commercially 

important fishes would respond similarly. At the projected rate of removal, these activities are not 

expected to have a substantial negative impact on stocks of commercially important fishes.

Pipeline trenching, dredging, and canal construction activities resuspend sediments. Depending on 

the sediment characteristics, sediment load, and duration of exposure, impacts to commercially valuable 

species within a sediment plume can vary. Responses range in severity from no effect to mortality, but 

mobile species can avoid severe effects by limiting exposure. Sessile organisms and those with limited 

mobility may be exposed for longer durations, leading to increasingly severe impacts (e.g., increased 

respiratory rates, reduced feeding, and mortality). However, sandy sediments are quickly redeposited 

within 400 m (1,312 ft) of a trench, and finer sediments are widely dispersed and redeposited over a 

period of hours to days within a few thousand meters of the event. No significant effects to commercial 

fisheries are anticipated as a result of pipeline trenching because these are localized, temporary events. 

The cumulative effect on commercial fisheries from pipeline trenching is not expected to be 

distinguishable from natural events or natural population variations.

Drilling mud discharges contain chemicals toxic to marine fishes that include brine, hydrocarbons, 

radionuclides, and metals. One of the main concerns of the concentrations of metals in the drilling muds 

is that mercury can be magnified in the food chain. Because of concern about bioaccumulation of 
Description of the Environment and Impact Analysis 4-153

mercury in some fishes (Oken et al., 2012), the Gulf of Mexico in general, and areas with OCS oil and gas 

infrastructure in particular, have been the subject of several studies on mercury concentrations in 

sediment and uptake of mercury associated with drilling. Recent studies have concluded that platforms 

do not contribute to higher mercury levels in marine organisms (Sluis et al., 2013). Offshore discharges 

of drilling mud have been shown to dilute to near background levels within 1,000 m (3,281 ft) of the 

discharge point and would not cause a concentration of mercury in the food chain. These discharges 

would therefore have a negligible cumulative effect on fisheries because of the dilution of the metal to 

background levels before it enters the food chain. Produced-water discharges (Chapter 3.1.1.4.2 of the 

2012-2017 WPA/CPA Multisale EIS) contain components and properties potentially detrimental to 

commercial fishery resources. However, offshore discharges of produced water also disperse and dilute 

to near background levels within 1,000 m (3,281 ft) of the discharge point and have a negligible 

cumulative effect on fisheries. No mortality has been attributed to produced-water discharges, and no 

consensus of sublethal effects to fish has been reported in the literature. Offshore discharges and 

subsequent changes to marine water quality are closely regulated by the U.S. Environmental Protection 

Agency’s NPDES permits. The input of drilling mud and produced waters are limited and are diluted 

very quickly in the marine environment. Their environmental effects are, therefore, expected to be 

limited.

Loss of well control and resultant blowouts in the Gulf OCS are uncommon and, since 1970, there 

have been only 13 losses of well control that have resulted in >50 bbl of oil being spilled. Oil spills, 

including catastrophic subsurface blowouts that include both oil and natural gas, have the potential to 

affect fish populations, in particular eggs and larvae. However, the probability of an offshore spill

impacting these nearshore environments is low, and oil would generally be volatilized or dispersed by 

currents in the offshore environment. The most damaging oil spills to commercial fisheries harvests 

would be those reaching the productive waters of the continental shelf or estuaries. However, while 

short-term negative impacts may be greatest on those populations that are short-lived and harvested 

annually, such as crabs and shrimp, or those populations that are sessile, such as oysters, these species 

have evolved to cope with high mortality through large population growth potential and should not suffer 

long-term population effects. Longer-lived species such as snapper and grouper have more resilience 

because these populations consist of multiple year-classes that can breed, and the failure of any one yearclass does not necessarily threaten the survival of the population. Historically, spills of sufficient 

magnitude to potentially and broadly affect these sensitive areas have a very low probability of 

occurrence. Furthermore, potential population losses may be somewhat offset by commercial fisheries

closure areas necessitated by a large spill.

The full effects of catastrophic subsurface blowouts, such as the Deepwater Horizon explosion, on 

individual fisheries in the Gulf of Mexico are currently unknown, but spills of this type are a lowprobability event. This type of spill is not expected to occur with a CPA proposed action. However, in 

the unlikely event a spill of that extent does occur, the potential impacts are discussed in Appendix B. 

Non-OCS Oil- and Gas-Related Impacts

There is competition among large numbers of commercial fishermen, commercial operations

employing different fishing methods, and commercial and recreational fishermen for a given fishery 

resource. The effects of overfishing of finfish resources are discussed in Chapter 4.1.1.19 of this 

Supplemental EIS and Chapter 4.2.1.19 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 

231 Supplemental EIS. When practiced nonselectively, fishing techniques such as trawling, gill netting, 

or purse seining may reduce the standing stocks of the desired target species. This can also significantly 

affect species other than the target. For example, bycatch of the commercial shrimping industry is 

believed to have been a significant factor in the population decline of red snapper. In addition, continued 

fishing of most commercial species at the present levels can result in rapid declines in the landings and 

the eventual failure of certain fisheries if not actively managed.

Space-use conflicts and conflicts over possession of the resources can result from different forms of 

commercial operations and can occur between commercial and recreational fisheries. These effects have 

resulted in State and Federal constraints such as weekday fishing only, quotas, and/or gear restrictions on 

commercial fishing activity. The Magnuson-Stevens Fishery Conservation and Management Act and its 

amendments address sustainable fisheries and set guidelines for protecting marine resources and habitat 

from fishing- and nonfishing-related activities. Under this Act, fisheries management plans, including 
4-154 Central Planning Area Lease Sales 235, 241, and 247 EIS

limits on catch and fishing seasons, are developed and proposed by the regional fisheries management 

councils for approval and implementation by NMFS. State agencies regulate inshore fishing seasons and 

limits. Another important consideration is the variability in fish populations, which fluctuate in numbers 

from year to year due to natural factors such as spawning success and juvenile survival.

The size of non-OCS oil- and gas-related or coastal spills is expected to be small and to cause a 

minimal decrease in commercial fishing activity local to the spill area. Because these spills are small, the 

resultant influence on commercial fishing, landings, or the value of those landings is not expected to be 

distinguishable from that of natural population variations.

The most serious impact on commercial fisheries is the cumulative loss of wetlands. Wetland loss as 

a result of commercial and residential development is one of the major factors in this trend, although this 

is regulated and mitigated by COE. Wetland conversion to open water results in a permanent loss of 

nursery and foraging habitat for many commercial fish stocks. The loss of wetlands also contributes to 

the intrusion of saltwater into oyster-producing waters, resulting in increased disease and predation. 

Resource management agencies, both State and Federal, set restrictions and issue permits in an effort to 

mitigate the effects of development projects and industry activities. The Federal and State governments 

are also funding research and coastal restoration projects; however, it may take decades of monitoring to 

ascertain the long-term feasibility of these coastal restoration efforts. In comparison to the large area of 

wetland loss due to commercial and recreational development (such as marinas and camps) as well as to 

natural forces such as hurricanes, any incremental wetland loss due to a CPA proposed action is expected 

to be minor. A detailed discussion of the impacts to wetlands due to commercial and recreational 

development can be found in Chapter 4.2.1.4 of the 2012-2017 WPA/CPA Multisale EIS, and updated 

information is provided in the WPA 233/CPA 231 Supplemental EIS. 

Hurricanes may impact commercial fishing by damaging gear and shore facilities, and by dispersing 

resources over a wide geographic area. Hurricanes may also affect the availability and price of key 

supplies and services (e.g., fuel), therefore affecting commercial fishing. Hurricanes suspend fishing 

activity and are destructive to wetlands that are nursery grounds to many commercial fish. Hurricanes 

can be extremely destructive to oyster beds by causing siltation over the beds and smothering spat along 

with adult oysters as evidenced by Hurricanes Katrina, Rita, Gustav, and Ike. Commercial fisheries

landings of the central Gulf Coast were drastically impacted by Hurricanes Katrina and Rita in 2005 as a 

result of the severe impact on coastal port facilities and fishing vessels. Equally as destructive were 

Hurricanes Gustav and Ike in 2008. These impacts to commercial fisheries from the hurricanes were so 

severe that Commerce Secretary Gutierrez determined a fisheries resource disaster as a result (Upton, 

2010). However, natural disaster impacts such as these are easily distinguished from incremental impacts 

of OCS activities.

Other phenomena that could impact commercial fisheries include hypoxia events and red and brown 

tides. Hypoxia events can kill or displace different species, such as brown shrimp, so they are more 

difficult to catch in known fishing grounds. Red and brown tides can close areas to fishing. A CPA 

proposed action is expected to have minimal additive adverse impacts on commercial fisheries when 

combined with other anthropogenic and natural disturbances.

Summary and Conclusion

Activities resulting from the OCS oil- and gas-related and non-OCS oil- and gas-related events have 

the potential to cause limited detrimental effects to commercial fishing, landings, and the value of those 

landings. The impact-producing factors of the cumulative scenario are the installation of production 

platforms and underwater OCS obstructions, production platform removals, seismic surveys and 

operational noise, petroleum spills, subsurface blowouts, pipeline trenching, offshore discharges of 

drilling mud and produced waters, commercial and recreational fishing techniques or practices 

(overfishing), wetland loss, hurricanes, and other phenomena.

The installation of each production platform excludes a small area from the resources available for 

most commercial fishing. However, even the cumulative impact of these exclusions is small in 

comparison to the total area available for commercial fishing in the CPA. Concerns that the areal 

comparison insufficiently considers geological formations and other features that constitute “highquality” fishing grounds are not justified since the stipulations and regulations currently in place protect 

these habitats from being impacted by OCS activities. Furthermore, the addition of OCS structures 

potentially enhances production for some commercially valuable species (Stone et al., 1979; Carr and 
Description of the Environment and Impact Analysis 4-155

Hixon, 1997; Gallaway et al., 2009; Shipp and Bortone, 2009). It is expected that these benefits, over the 

40-year analysis period, will outweigh the localized disturbances and fish mortality resulting from 

exploration, installation, and decommissioning activities. Because the impacts from platform removals 

are so localized, the cumulative impact of these activities to commercial fisheries is anticipated to be 

minor. The effects of seismic surveys have been determined to be limited in time and space. The effects 

of seismic surveys are, therefore, expected to be minimal overall.

Subsurface blowouts, such as the Deepwater Horizon explosion that include both oil and natural gas, 

have the potential to affect fish populations, particularly eggs and larvae. The potential impacts are 

discussed in Appendix B. Because spills of this magnitude are low-probability events, their contribution 

to the cumulative impact on commercial fisheries populations is not expected to be large as a result of a 

CPA proposed action.

Significant contributions to cumulative impacts from OCS oil- and gas-related and non-OCS oil- and 

gas-related activities are not anticipated as a result of pipeline trenching because sandy sediments are 

quickly redeposited within 400 m (1,312 ft) of a trench and because finer sediments are widely dispersed 

and redeposited over a period of hours to days within a few thousand meters of the event. These are small 

areas as compared with the rest of the Gulf of Mexico, and they are temporary disturbances.

Offshore discharges of drilling mud have been shown to dilute to near background levels within 

1,000 m (3,281 ft) of the discharge point. The mercury in sediments near drilling platforms is not in a 

bioavailable form. For these reasons stated here and in the section above, the contribution of drilling 

discharge and produced-water discharge to the cumulative impacts of a CPA proposed action is not 

anticipated to be significant.

Overfishing (including bycatch) has contributed to the decline of some populations of commercial 

fish species in the Gulf of Mexico. It is the responsibility of the regional fisheries management councils 

and NMFS to propose, implement, and enforce guidelines for protecting marine resources and habitat 

from fishing- and nonfishing-related activities.

Overall, of the many anthropogenic and natural factors impacting fish resources in the Gulf of 

Mexico, those stemming directly from OCS oil- and gas-related activities are federally regulated or 

mitigated, and are small. Commercial fish and shellfish populations have remained relatively healthy in 

the Gulf of Mexico in spite of ongoing anthropogenic and natural disturbances. Compared with non-OCS 

oil- and gas-related activities, the incremental effect of a CPA proposed action is not expected to be 

significant.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A thorough search of information sources, including Internet research databases (EBSCO, PLoS 

ONE, JSTOR, Elsevier, and BioOne), coastal universities, and State and Federal environmental agencies, 

was conducted to determine the availability of new pertinent scientific information since the publication 

of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. Information 

relevant to this analysis is summarized below.

Two separate studies investigating potential impacts from the Deepwater Horizon oil spill on eastern 

oysters (Crassostrea virginica) were recently published. In the first, oysters that were transplanted 

before, during, and after the Deepwater Horizon oil spill, in areas of Mobile Bay and the Mississippi and 

Alabama coast that were potentially exposed to oil, did not show evidence of oil-derived C and N in their 

shells or tissue (Carmichael et al., 2012). This finding indicates that the oysters sampled were either not 

exposed to oil, did not feed on oiled food sources, or consumed too little oiled food to detect in their 

shells and tissue. It is also possible that the oysters rapidly depurated any consumed oil or slowed filter 

feeding due to the stress of oil exposure. Whatever the reason, because oysters did not assimilate oilderived C and N, they did not provide a contaminated food source to higher trophic levels (Carmichael 

et al., 2012). In the second study, oysters collected from oil exposed areas of Mississippi Sound 6 months 

after the Macondo well was capped did not show PAH accumulation (Soniat et al., 2011). Although the 

study was limited, the observed oyster condition, infection rate, and reproductive state were within 

expected ranges for oysters sampled at the salinities recorded, but not exposed to oil. Both oyster studies 

caution, however, that sample sizes were small and the findings of the study should not be extrapolated to 

all oysters in the GOM.
4-156 Central Planning Area Lease Sales 235, 241, and 247 EIS

The NMFS has released its annual update to its Fisheries Economics of the U.S. report (USDOC, 

NMFS, 2012). This report provides a variety of information regarding the economic significance of 

commercial fishing activity in the Nation, by region and state. Table 4-2 presents data from this report on 

each State’s landings revenue, sales impacts, job impacts, and commercial fishing location quotient 

(CFLQ). In 2011, landings revenue in all Gulf Coast States except Mississippi was higher than in any 

year from 2002 through 2010. Landings revenue in Mississippi was higher in 2011 than in 2010 but still 

lower than levels that prevailed in prior years; this is largely because Gulf menhaden (Brevoortia 

patronus) prices in Mississippi fell from 0.08 cents per pound in 2009 and 2010 to 0.04 cents per pound 

in 2011. While Louisiana had the highest landings revenue, Florida had the largest amount of sales and 

job impacts due its large seafood processing industry. The final column in Table 4-2 presents each state’s 

CFLQ, which is a measure of the scale of the seafood industry in each state relative to that state’s total 

economy. Louisiana has the highest CFLQ in the Gulf (1.58), which means that the seafood industry is 

1.58 times as large in Louisiana as in the average U.S. state.

The NMFS reports each year to the Congress and Fishery Management Councils on the status of all 

fish stocks in the Nation. As of the 2012 status report (USDOC, NMFS, 2013d), overfished species in the 

Gulf of Mexico are red snapper, greater amberjack (Seriola dumerili), gag grouper (Mycteroperca 

microlepis), and gray triggerfish (Balistes capriscus). Although the report has been updated, there have 

been no changes in the species considered overfished in the Gulf of Mexico. Annual landings data may 

be obtained from NMFS’s website (USDOC, NMFS, 2014b). These data are updated regularly, but 

delays in submission and processing may lead to data discrepancies between extracts over a period of 

months or years; refer to the website for the most up-to-date commercial fisheries information. Annual 

landings are subject to a wide array of factors that result in fluctuations from year to year. Many State 

and Federal agencies have shared or sole responsibility for implementing the laws and regulations within 

their jurisdiction, ensuring that coastal development and industrial operations are performed responsibly 

and that potential impacts are avoided or properly mitigated. The Magnuson-Stevens Fishery 

Conservation and Management Act and its amendments address sustainable fisheries and set guidelines 

for protecting marine resources and habitat from fishing- and nonfishing-related activities. Under this 

Act, fisheries management plans, including limits on catch and fishing seasons, are developed and

proposed by the regional fisheries management councils for approval and implementation by NMFS. 

State agencies regulate inshore fishing seasons and limits. Furthermore, natural variability in spawning 

success and recruitment affect populations, and severe weather events and persistent changes in 

environmental conditions may also elicit species-specific responses that impact fishing success in any 

given year.

In 2012, Gulf menhaden constituted the largest Gulf fishery, by weight, although landings were at the 

lowest level since 2006. White shrimp (Litopenaeus setiferus) catch was at its highest since 2009, but 

brown shrimp (Farfantepenaeus aztecus) production in the Gulf was down from 2011. Blue crab 

(Callinectes sapidus) harvest was down slightly from 2011, but the value increased. The eastern oyster 

harvest was the highest since 2009 and the total value of the harvest was the highest in the past 10 years. 

Red snapper landings have increased for the past 5 years, but it is worth noting that quota increases have 

also occurred in each of the past 4 years (GMFMC, 2013).

As discussed in Chapter 4.2.1.19 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS, BOEM has identified incomplete information regarding impacts of the Deepwater

Horizon explosion, oil spill, and response to commercial fish species in the CPA. This information 

cannot be obtained because the overall costs are exorbitant. This incomplete information may be relevant 

to evaluating adverse effects because the full extent of potential impacts on commercially valuable 

species and commercial harvests are not known. BOEM used existing information and reasonably 

accepted scientific methodologies to extrapolate from available information in completing the relevant 

analysis, such as studies investigating the evidence of oil and impacts stemming from exposure to oil in 

oysters, and NMFS stock assessments and reports. None of these sources reveal reasonably foreseeable 

significant adverse impacts. For example, studies of oysters from areas known or suspected to have been 

exposed to oil have not found evidence of significant adverse impacts, and the organizations responsible 

for fisheries management have not reported stock or harvest fluctuations outside the range of historical 

variation for commercially important species such as brown shrimp and Gulf menhaden. Although the 

body of available information is incomplete and long-term effects cannot yet be known, the evidence 

currently available supports past analyses and does not indicate severe adverse impacts to commercial 
Description of the Environment and Impact Analysis 4-157

fisheries. Therefore, BOEM has determined that the information is not essential to a reasoned choice

among alternatives.

4.1.1.20.Recreational Fishing

BOEM has reexamined the analysis for recreational fishing presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

recreational fishing presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analyses and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

A detailed description of recreational fishing and the full analyses of the potential impacts of routine 

activities and accidental events associated with a CPA proposed action are presented in Chapter 4.2.1.20 

of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.20 of 

the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the 

cumulative impacts is presented below. Any new information that has become available since the 

publication of these documents is presented below.

Impacts of Routine and Accidental Events

A detailed analysis of the routine impacts of proposed CPA Lease Sales 235, 241, and 247 on 

recreational fishing can be found in Chapter 4.2.1.20 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.20 of the WPA 233/CPA 231 Supplemental EIS.

Activities during the initial phases of a CPA proposed action, such as seismic surveying operations 

and other forms of vessel traffic, may lead to some space-use conflicts with recreational fishermen. 

Vessel traffic during subsequent infrastructure emplacement, structure installation, and production 

operations could also lead to some space-use conflicts with recreational fishing activities. The OCS oiland gas-related activities could also affect the aesthetics of fishing in a particular location, which could 

dissuade anglers from fishing in specific locations. Proposed CPA Lease Sales 235, 241, and 247 may 

also lead to low-level environmental degradation of fish habitat (Chapter 4.1.1.18), which would 

negatively impact recreational fishing activity. However, these minor negative effects would likely be 

outweighed by the beneficial addition of hard substrate and complex habitat provided by oil and gas 

infrastructure. The level of participation in any particular State Rigs-to-Reefs program will be an 

important determinant of the long-term impact of a CPA proposed action on recreational fishing activity. 

As structures are scheduled for decommissioning, a higher level of participation may benefit fishermen 

through the retention of complex habitat and potentially enhanced production for some recreationally 

desirable species, as opposed to structure removals (particularly those that use explosives) that can 

negatively impact the recreational activity that depends on any particular platform.

A detailed analysis of the accidental impacts that may be associated with proposed CPA Lease Sales 

235, 241, and 247 on recreational fishing can be found in Chapter 4.2.1.20 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.20 of the WPA 233/CPA 231 

Supplemental EIS.

Oil spills can arise from accidents with respect to vessels, pipelines, drilling operations, or production 

operations. An oil spill would likely lead to recreational fishing closures in the vicinity of the oil spill. 

Small-scale spills should not affect recreational fishing to a large degree due to the likely availability of 

substitute fishing sites in neighboring regions. The longer-term effects of an oil spill will be determined 

by its effects on fish populations (Chapter 4.1.1.18), as well as by its effects on people and firms that 

support recreational fishing activity. The impacts of low-probability catastrophic oil spills are described 

in Appendix B. 

Summary and Conclusion

BOEM has reexamined the analysis for recreational fishing presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for 

recreational fishing presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 
4-158 Central Planning Area Lease Sales 235, 241, and 247 EIS

Supplemental EIS because the new information was consistent with prior expectations. The analysis and 

potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 

231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

The cumulative impacts to recreational fishing activity will arise from a CPA proposed action, the 

existing OCS Program, and the expected progression of the recreational fishing industry in the Gulf of 

Mexico. These impacts would arise from the cumulative effects on fish resources in the Gulf of Mexico, 

which are discussed in Chapter 4.1.1.18. Because many of the recreationally sought fishes are also 

harvested commercially, a number of the cumulative impacts to the recreational fishing industry are 

similar to those of the commercial fishing industry (Chapter 4.1.1.19). This is true even though 

recreational fishing is primarily confined to smaller, closer inshore areas of the Gulf of Mexico than 

commercial fishing. The cumulative impacts unique to recreational fishing activity are discussed below.

OCS Oil- and Gas-Related Impacts 

Routine OCS Processes

The impacts of production platforms, underwater obstructions, seismic surveys, pipeline trenching, 

and discharges of drilling mud and produced waters on commercial fishing activity are discussed in 

Chapter 4.1.1.19. The impacts of these factors will be similar for recreational fishing activity to a large 

extent. In particular, these routine processes can cause space-use conflicts and can impact the habitats of 

certain fish species. The main difference is that recreational fishing activity generally occurs closer to 

shore than commercial fishing; therefore, these impacts will occur for recreational fishing activity mainly 

if these activities occur close to shore. Recreational fishing activity could also be negatively impacted if 

the aforementioned activities temporarily negatively affect the aesthetics of fishing in nearby areas. For 

example, the visual impacts or the noise impacts from OCS oil- and gas-related activities and structures 

could dissuade anglers from fishing in a certain location. However, in most instances, there would likely 

be a number of suitable substitute recreational fishing sites if any temporary disruptions arose due to OCS 

oil- and gas-related activities.

Oil Spills

A CPA proposed action would contribute to the risk of an oil spill arising from the broader OCS 

Program. An oil spill would likely lead to recreational fishing closures in the vicinity of the oil spill. 

Small-scale spills should not affect recreational fishing to a large degree due to the likely availability of 

substitute fishing sites in neighboring regions. The longer-term effects of an oil spill will be determined 

by its effects on fish populations (Chapter 4.1.1.18). The impacts of a low-probability catastrophic oil 

spill are discussed in Appendix B. 

Artificial Reef Development and Structure Removals 

Proposed CPA Lease Sales 235, 241, and 247 are expected to result in oil and gas development, and 

the semipermanent addition of artificial substrate in the form of platforms and supporting infrastructure. 

These structures incidentally serve as artificial reefs for the duration of their life cycle, providing habitat 

for some epifauna and associated fish communities. The extent to which a platform will support 

recreational fishing activity is dependent on fish species in the area and accessibility to recreational 

fishermen.

Since oil/gas platforms are hypothesized to attract and/or support a large fish population, the effects 

of OCS oil- and gas-related actions become particularly important during the decommissioning stage of 

an oil platform’s life cycle. Namely, the removal of a platform from a particular site has the potential to 

damage the fish assemblages associated with that structure. This in turn will also affect recreational 

fishing activity in a particular area. Gitschlag et al. (2000) conducted an analysis of the impacts to fish 

populations from the use of explosives to remove decommissioned oil platforms. They found that species 
Description of the Environment and Impact Analysis 4-159

such as red snapper and sheepshead are particularly vulnerable to the use of explosives; however, they 

also reported that the scale of these impacts relative to the stock of these species were relatively small at 

the sites that were included in the study.

As an alternative to removing an oil platform, the owner of an oil platform has the option to apply for 

participation in the Rigs-to-Reefs program of the appropriate state. These programs allow for portions of 

oil platforms to remain in the water as reefs after the productive life of a platform has ended. Platforms 

that are a part of these programs are either toppled in place or are moved to a location that is a suitable 

fish habitat. The U.S. policy towards artificial reef creation is outlined in the National Artificial Reef 

Plan: Guidelines for Siting, Construction, Development, and Assessment of Artificial Reefs (USDOC, 

NOAA, 2007). The BSEE policy regarding Rigs-to-Reefs programs is outlined in Rigs-to-Reefs Policy, 

Progress, and Perspective (Dauterive, 2000) and was updated in Rigs to Reefs Policy Addendum: 

Enhanced Reviewing and Approval Guidelines in Response to the Post-Hurricane Katrina Regulatory 

Environment (USDOI, MMS, 2009c) in light of Hurricane Katrina. Hiett and Milon (2002) present 

estimates of the scale of recreational fishing activity near oil and gas structures. This study found that 

20 percent of private boat fishing, 32 percent of charter boat fishing, 51 percent of party boat fishing, and 

94 percent of diving activities in Texas, Louisiana, Mississippi, and Alabama occur near oil and gas 

structures.

Deepwater Horizon Explosion, Oil Spill, and Response 

The Deepwater Horizon explosion, oil spill, and response may make recreational fishing activity in 

the GOM more sensitive to additional oil spills that may occur. This is because the fish populations in the 

Gulf of Mexico are still responding to the spill, the ultimate outcome of which is not yet clear (Chapter 

4.1.1.18). The particular sensitivity of recreational fishing to the Deepwater Horizon explosion, oil spill, 

and response is also due to the complex manner in which recreational fishing activity and tourism

interact. Namely, recreational fishing activity is one of a number of factors that draw tourists to a 

particular region. The high level of national attention focused on the Deepwater Horizon explosion, oil 

spill, and response suggests that future oil spills, even if smaller in scale, could raise greater concerns 

regarding recreational fishing in affected areas among tourists. While this effect may be offset by 

additional fishing by others, any decrease in fishing-based tourism could have broader impacts to a local 

economy.

Non-OCS Oil- and Gas-Related Impacts

State and Federal Fisheries Management Plans 

State and Federal Fisheries Management Plans determine the manner in which recreational fishing

activities can occur in any particular area. Recreational fishing activity is highly regulated, primarily to 

ensure a sustainable fisheries population through time. This often takes the form of catch limits per trip 

and quotas for overall catch per species during a given season. Recreational fishing activity in Federal 

waters is governed by the Gulf of Mexico Fishery Management Council (GMFMC). Each State has its 

own guidelines for recreational fishing in State waters. Fisheries Management Plans could serve to 

mitigate the effects of an oil spill since these plans are often designed to maintain stable fishing activity. 

For example, the GMFMC allowed for a supplemental red snapper season in October 2010 since red 

snapper catch was unusually low during the Deepwater Horizon explosion, oil spill, and response 

(GMFMC, 2010). This supplemental red snapper season was designed to allow the 2010 quota for red 

snapper catch to be reached.

Hurricanes

The impacts of a CPA proposed action on recreational fishing should be viewed in light of the 

ongoing risk of hurricanes in the Gulf of Mexico. Hurricanes cause short-term disruptions to recreational 

fishing activity in the immediate geographic area. Recreational fishing activity is also vulnerable to the 

disruptions in overall tourism activity that would arise in light of a hurricane. Finally, hurricanes can 

degrade the wetland areas that play important roles in fish ecosystems (Chapter 4.1.1.4). 
4-160 Central Planning Area Lease Sales 235, 241, and 247 EIS

Economic Factors 

The level of recreational fishing activity is dependent on various economic factors. Recreational 

fishing activity will likely positively correlate to overall economic conditions. This is both due to the 

costs of recreational fishing activity and to the tendency of consumers to direct lower levels of spending 

towards leisure activities during a recession. Recreational fishing activity should also correlate with 

broader tourism trends in particular areas. In addition, recreational fishing activity will likely correlate 

with trends in input costs, particularly fuel prices. Finally, recreational fishing activity is fairly seasonal, 

often peaking during summer months. The NMFS provides angler effort data in 2-month increments. In 

2012, the percentage of overall angler effort that occurred in each 2-month period in Louisiana, 

Mississippi, Alabama, and West Florida combined were as follows: January/February (13.0%); 

March/April (16.4%); May/June (22.0%); July/August (21.6%); September/October (15.4%); and 

November/December (11.7%).

State Oil and Gas Activities

State oil and gas activities will impact recreational fishing in the GOM. The space-use conflicts and 

the impacts of accidental events are similar to the impacts that will arise from the OCS Program. 

However, since recreational fishing activity usually occurs fairly close to shore, State activities that occur 

in popular fishing areas will have more noticeable impacts. For example, the impacts of artificial reefs

and structure removals discussed above have the potential to have more noticeable effects in State waters.

Space-Use Conflicts

There are a variety of activities that could create space-use conflicts with recreational fishermen. 

Some of these activities include military vessel traffic, recreational vessel traffic, and commercial fishing

activities. The extent of these conflicts would depend on their proximity to recreational fishing areas, 

which are often fairly close to shore.

Summary and Conclusion

A CPA proposed action and the broader OCS Program have varied effects on recreational fishing

activity. The OCS Program has generally enhanced recreational fishing opportunities due to the role of 

oil platforms as artificial reefs. This effect depends importantly on the extent to which rigs are removed 

at decommissioning or are maintained through Rigs-to-Reefs programs. However, oil spills can have 

important negative consequences on recreational fishing activity due to the resultant fishing closures and 

longer-term effects oil spills can have on fish populations. These are discrete and rare events, however, 

and recreational fishing activity is largely driven by broader economic and tourism trends. Recreational 

fishing activity is also influenced by a number of non-OCS oil- and gas-related activities, particularly 

those that could impact fishing grounds such as wetlands areas. In addition, it is likely that Fisheries

Management Plans of the Federal and State governments would serve to keep overall recreational fishing 

activity reasonably stable through time. The incremental contribution of a CPA proposed action to these 

positive and negative cumulative effects would be minimal.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

BOEM examined a variety of Internet sources, as well as known data providers, for new information 

regarding the impacts of a CPA proposed action on recreational fishing. The primary new data source is 

an annual update to recreational fishing data provided by NMFS (USDOC, NMFS, 2013f). This data 

source provides data on both the species caught and the amount of angler effort in any particular year. 

Table 4-3 presents data on the number of angler trips taken in Louisiana, Mississippi, Alabama, and West 

Florida from 2008 to 2012. In these states combined, there were 24.8 million angler trips in 2008, 

22.6 million angler trips in 2009, 21.0 million angler trips in 2010, 22.6 million angler trips in 2011, and 

23.2 million angler trips in 2012. Table 4-3 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. For the Gulf as a 
Description of the Environment and Impact Analysis 4-161

whole, all forms of ocean-based fishing were higher in 2012 than in 2011. Shore-based and charter-based 

inland recreational fishing increased in 2012, while private/rental-based inland recreational fishing 

slightly decreased in 2012. Overall recreational fishing activity in West Florida and Mississippi was 

slightly higher in 2012 than in 2011, while recreational fishing activity in Alabama and Louisiana was 

slightly lower in 2012 than in 2011.

Table 4-4 presents data on the most commonly landed species by recreational fishermen (both in 

terms of numbers of fish and pounds of fish) in Louisiana, Mississippi, Alabama, and West Florida 

combined during each year from 2008 through 2012. Landings for most species were roughly consistent 

with landings observed in prior years. However, there were higher landings of species such as gray 

snapper (Lutjanus griseus), pinfishes (Lagodon rhomboides), and blackfin tuna (Thunnus atlanticus) in 

2012 than in prior years. There were lower landings of species such as gag (Mycteroperca microlepis) 

and greater amberjack (Seriola dumerili). 

The NMFS has also released its annual update to its Fisheries Economics of the U.S. 2011 report 

(USDOC, NMFS, 2012). This report presents various data regarding the economic significance of 

recreational fishing in the Gulf of Mexico. Table 4-5 presents data from this report on expenditures, 

sales, value added, and employment in each Gulf Coast State. Recreational fishing activity supported 

$9.8 billion in expenditures, $9.3 billion in sales, $4.8 billion in value added, and 89,319 jobs in the Gulf 

of Mexico in 2011. The largest economic impacts from recreational fishing occurred in West Florida. 

Louisiana and Texas had the next largest impacts, followed by Alabama and Mississippi.

4.1.1.21.Recreational Resources

BOEM has reexamined the analysis for recreational resources presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

recreational resources presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

A detailed description of recreational resources and the full analyses of the potential impacts of 

routine activities and accidental events associated with a CPA proposed action are presented in the 

Chapter 4.2.1.21 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.21 of the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental 

contribution to the cumulative impacts is presented below. Any new information that has become 

available since the publication of these documents is presented below.

Impacts of Routine and Accidental Events

Routine OCS actions in the CPA can cause various disturbances to recreational resources. For 

example, marine debris can noticeably affect the aesthetic value of coastal areas, particularly beaches. 

Vessel noise and the visibility of OCS infrastructure can also conflict with some recreational activities. 

Similarly, vessel traffic can cause space-use conflicts with recreational activities. The OCS activities can 

also change the composition of local economies through changes in employment, land use, and demand 

for activities related to recreation and tourism. The presence of OCS oil and gas platforms can enhance 

some recreational activities such as fishing and diving, although the long-term impacts of platforms 

depend on the nature of the decommissioning of the platform. However, the small scale of a CPA 

proposed action relative to the scale of the existing oil and gas industry suggests that these potential 

impacts on recreational resources are likely to be minimal.

A detailed analysis of the routine impacts of a CPA proposed action on recreational resources can be 

found in Chapter 4.2.1.21.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.21 of the WPA 233/CPA 231 Supplemental EIS.

Accidental spills most likely to result from a CPA proposed action will be small, of short duration, 

and not likely to impact Gulf Coast recreational resources. Should an oil spill occur and contact a beach 

area or other recreational resource, it will cause some disruption during the impact and cleanup phases of 

the spill. Beaches, nature parks, and wetland areas could be impacted during these phases of a spill. 

These disruptions could also have impacts on firms and consumers that depend on the use of these 
4-162 Central Planning Area Lease Sales 235, 241, and 247 EIS

resources. Media coverage and public perception regarding the extent of the oil damage can also 

influence the ultimate economic impacts of the spill. The economic impacts of a spill would be mitigated 

to some extent if a legal damage claims process were to be implemented subsequent to an oil spill. 

However, all of these effects would likely be small in scale and of short duration.

A detailed analysis of the accidental impacts of a CPA proposed action on recreational resources can 

be found in Chapter 4.2.1.21.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.21 of the WPA 233/CPA 231 Supplemental EIS.

Summary and Conclusion

BOEM has reexamined the analysis for recreational resources presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for 

recreational resources presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS because the new information was roughly consistent with prior expectations. The 

analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the 

WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

The cumulative impacts to recreational resources would occur due to a CPA proposed action, the 

existing OCS Program, and various non-OCS events and actions. A CPA proposed action would 

contribute to a number of aesthetic, space-use, oil-spill, and infrastructure emplacement and removal 

impacts arising from existing and future oil and gas programs. Recreational resources along the Gulf 

Coast can also be impacted by non-OCS aesthetic and space-use conflicts, as well as a variety of other 

factors, such as coastal erosion, beach disruptions, impacts from military operations, and economic 

factors. 

OCS Oil- and Gas-Related Impacts 

Aesthetic Impacts

A CPA proposed action would contribute to effects of the overall OCS Program. For example, the 

94,000-168,000 service-vessel trips and 696,000-1,815,000 helicopter operations that are projected to 

arise from a CPA proposed action would contribute to the 3,310,000-4,382,000 service-vessel trips and 

28,710,000-55,605,000 helicopter operations that are projected to arise from the entire OCS Program 

from 2012 to 2051. These activities would have some aesthetic impacts on recreational resources. For 

example, the OCS Program contributes to the marine debris problems along the Gulf Coast. The BSEE 

guidance regarding marine debris prevention is outlined in NTL 2012-BSEE-G01, “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. 

These various laws and regulations will likely minimize the potential damage to recreational resources 

from the discharge of marine debris from non-OCS oil- and gas-related operations.

There are also potential negative impacts on beach tourism from vessel noise and from the visibility 

of OCS infrastructure. While the potential effects of noise on tourism are difficult to quantify, several 

characteristics of the OCS oil and gas industry serve to minimize these effects. First, most OCS oil- and 

gas-related vessel traffic moves between onshore support bases and production areas far offshore. 

Support bases are located in industrial ports, which are usually distant from recreational use areas. 

Second, OCS vessel use of approved travel lanes should keep noise fairly transitory and thus unlikely to 

noticeably impact tourism. The extent to which the visibility of an OCS platform would affect tourism 

would depend on the size and distance from shore of a particular platform.
Description of the Environment and Impact Analysis 4-163

Space-Use Conflicts

A CPA proposed action would also contribute to space-use conflicts between recreational activities 

and the broader OCS Program. Space-use conflicts could arise particularly near Port Fourchon

(Lafourche Parish, Louisiana) due to the high concentration of the OCS oil and gas industry in this area. 

The vessel traffic near OCS 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 recreational sites would be available. In addition, given the entrenched nature of the 

OCS oil and gas industry along the Gulf Coast, it is unlikely that any particular OCS oil- and gas-related

action would significantly add to space-use conflicts in this area.

Oil Spills

A CPA proposed action would contribute incrementally to the likelihood of an oil spill caused by the 

broader OCS Program. Accidental spills most likely will be small, of short duration, and not likely to 

impact Gulf Coast recreational resources. Should an oil spill occur and contact a beach area or other 

recreational resource, it will cause some disruption during the impact and cleanup phases of the spill. 

However, these effects are also likely to be small in scale and of short duration. An OCS oil- and gasrelated activity could also contribute to the possibility of a low-probability catastrophic oil spill, which is 

not reasonably foreseeable and not part of a CPA proposed action; the impacts of a catastrophic oil spill 

on recreational resources are discussed in Appendix B. 

Infrastructure Emplacement and Removal 

Routine OCS oil- and gas-related actions 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 actions on coastal beaches and dunes is presented in Chapter 4.1.1.3. Further 

information on the cumulative impacts of OCS oil- and gas-related activities on wetlands resources can be 

found in Chapter 4.1.1.4. These effects could cause impacts to recreational activities, such as fishing and 

wildlife viewing, which depend on beaches and wetland areas. However, platform emplacements can 

encourage some recreational activities, such as diving. However, decommissioning of these structures 

can have negative impacts on recreational diving if a particular platform were a popular diving site.

Non-OCS Oil- and Gas-Related Impacts

Aesthetic Impacts

Marine debris can noticeably affect the aesthetic value of coastal areas, particularly beaches. This is 

particularly true given the high levels of marine debris that already exist in some areas. Non-OCS oiland 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. Adler et al. (2009) present a broad overview of the nature of the marine debris problem. Various 

government agencies participate in a coordinated effort to combat marine debris; a broad summary of the 

issues involved and the policy structure with respect to marine debris can be found in the report of the 

Interagency Marine Debris Coordinating Committee (USDOC, NOAA, 2008). There is also a national 

monitoring program in place to track the progression of the marine debris problem in various locations. 

Ocean Conservancy (2007) describes the structure of the National Marine Debris Monitoring Program, as 

well as the methods used to measure marine debris on various coastlines. McIlgorm et al. (2009) present 

an economic analysis of the costs of marine debris and of programs designed to minimize debris. This 

study explains that marine debris has a particular impact on fishing activity, the shipping industry, 

tourism activity, and on activities related to marine ecosystems. 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.
4-164 Central Planning Area Lease Sales 235, 241, and 247 EIS

Space-Use Conflicts

State oil and gas activities would contribute to the space-use and aesthetic conflicts experienced by 

the Gulf Coast. For example, State oil and gas platforms are closer to shore than OCS platforms and thus 

would be more likely to impact the viewshed from certain areas. State oil and gas helicopter and vessel 

traffic could would also have visual and noise impacts, which would have impacts on recreational 

experiences if those activities occur near popular recreation and tourism locations.

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. An overview of issues related to 

coastal erosion can be found in Evaluation of Erosion Hazards (The Heinz Center, 2000). This study 

characterizes the changes in the shorelines along the United States (including the Gulf Coast), describes 

the National Flood Insurance Program, describes current approaches to erosion management, describes 

the economic impacts of erosion, and discusses various policy options. The ongoing risk of hurricanes is 

a particular coastal erosion threat in the Gulf of Mexico; coastal erosion also lessens protection against 

future hurricanes. More information regarding these issues can be found in Chapters 4.1.1.3, 4.1.1.4, 

and 4.1.1.23.1. 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 a variety of ocean processes. For example, red 

tides, which are caused by growth of microscopic algae, can negatively affect the aesthetic value of 

beaches. Red tides can also cause respiratory problems and skin irritation for beachgoers (Mote Marine 

Laboratory, 2013). The recreational value of beaches can also be negatively impacted by degradations of 

air quality and water quality (Chapters 4.1.1.1 and 4.1.1.2). 

Military Operations

There are areas in the CPA where both OCS oil- and gas-related activities and military operations 

occur. Military operations in these areas can cause both space-use conflicts and aesthetic impacts to 

recreational resources. These effects would largely occur to offshore recreational activities such as 

boating, although aesthetic impacts could occur to onshore resources such as beaches if the military 

activities occurred close enough to these activities.

Impacts due to Economic Factors 

The recreational resources along the Gulf Coast will 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 will be influenced by national 

economic trends. Recreational and tourism activity is positively correlated to the state of the overall 

economy, primarily 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 4.1.1.23.3. 

Summary and Conclusion

A CPA proposed action would contribute to a number of aesthetic, space-use, oil spill, and 

infrastructure emplacement and removal impacts arising from existing and future oil and gas programs. 

Recreational resources along the Gulf Coast can also be impacted by non-OCS oil- and gas-related 

aesthetic and space-use conflicts, as well as a variety of other factors, such as coastal erosion, beach 

disruptions, and economic factors. However, the incremental contribution of a CPA proposed action is 
Description of the Environment and Impact Analysis 4-165

expected to be minimal in light of all OCS oil- and gas-related and non-OCS oil- and gas-related 

activities. This is because of the small scale of a CPA proposed action, as well as the fact that most 

impacts to recreational resources will be temporary.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

BOEM conducted a search of Internet sources and known data providers for new information 

regarding recreational resources. The Bureau of Labor Statistics has released final data regarding the 

scale of employment in various industries in Gulf Coast States in 2012 (U.S. Department of Labor, 

Bureau of Labor Statistics, 2013). Table 4-6 presents data on the levels of employment in leisure and 

hospitality industries in various Economic Impact Areas (EIA’s) and coastal areas. Leisure and 

hospitality employment was higher in 2012 than in any year from 2008 through 2011 in all EIA’s and 

coastal areas. This is likely primarily due to the gradual improvement in overall economic conditions 

since the most recent economic recession.

Lowe and Stokes (2013) presents a variety of information regarding the scale of wildlife tourism in 

various Gulf Coast areas. For example, this report finds that over 1,100 wildlife guide businesses support 

over 11,000 dining and lodging businesses. This report also estimates 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.

New data regarding the extent of shoreline oiling arising from the Deepwater Horizon oil spill has 

become available (USDOC, NOAA, 2013d). These data show that the majority of the shoreline of 

Louisiana has been cleaned. However, some areas, particularly areas near Chandeleur Sound and 

Barataria Bay, still had areas of oiled shoreline (the data were as of October 24, 2013). Finally, Ocean 

Conservancy (2013) provides data regarding the levels of marine debris found on the coastlines of various 

states. The amounts of trash found on the coastlines of the states along the Gulf of Mexico were (the data 

are presented in terms of pounds of trash): Alabama (173,637); Florida (428,962); Louisiana (7,801); 

Mississippi (54,680); and Texas (305,560).

Incomplete or unavailable information related to recreational resources may be relevant to reasonably 

foreseeable adverse impacts on these resources, as described in this chapter and in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. With regard to the Deepwater

Horizon explosion, oil spill, and response, BOEM has determined that the incomplete or unavailable 

information would not be essential to a reasoned choice among alternatives for the reasons described 

herein and in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

4.1.1.22.Archaeological Resources

4.1.1.22.1. Historic

BOEM has reexamined the analysis for historic archaeological resources presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented below. No new significant information was discovered that would alter the impact conclusion 

for historic archaeological resources presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 

WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

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

CPA proposed action are presented in Chapter 4.2.1.22.1.2 and 4.2.1.22.1.3 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.22.1 of the WPA 233/CPA 231 

Supplemental EIS. A CPA proposed action’s incremental contribution to the cumulative impacts is 

presented below. Any new information that has become available since those documents were prepared is 

presented below.
4-166 Central Planning Area Lease Sales 235, 241, and 247 EIS

A detailed description of historic archaeological resources can be found in Chapter 4.2.1.22.1.1 of the 

2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.22.1 of the 

WPA 233/CPA 231 Supplemental EIS.

Impacts of Routine and Accidental Events

Routine impact-producing factors associated with a CPA proposed action that could affect historical 

archaeological resources include direct physical contact with a shipwreck site; the placement of drilling 

rigs and production systems on the seafloor; pile driving associated with platform emplacement; pipeline 

placement; dredging of new channels, as well as maintenance dredging of existing channels; anchoring 

activities; pipeline installation; post-decommissioning trawling clearance; and the masking from 

geophysical sensors of archaeological resources from industry-related debris. A detailed impact analysis 

of the routine impacts from OCS activities associated with proposed CPA Leases Sale 235, 241, and 247 

on historic archaeological resources can be found in Chapter 4.2.1.22.1.2 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.22.1 of the WPA 233/CPA 231 

Supplemental EIS.

The greatest potential impact to an archaeological resource as a result of a CPA proposed action 

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

emplacement, and dredging or pipeline project) and a historic site because of incomplete knowledge of 

the location of these sites in the Gulf. The risk of contact to archaeological resources is greater in 

instances where archaeological survey data are inadequate or unavailable. Such an event could result in 

the disturbance or destruction of important archaeological information. Archaeological surveys provide 

the necessary information to develop avoidance strategies that reduce the potential for impacts on 

archaeological resources.

Archaeological surveys, where required prior to an operator beginning oil and gas activities on a 

lease, are expected to be effective at identifying possible archaeological sites. The technical requirements 

of the archaeological resource reports are detailed in NTL 2005-G07, “Archaeological Resource Surveys 

and Reports.” Under 30 CFR § 550.194(c) lessees are required to immediately notify BOEM’s Regional 

Director of the discovery of any potential archaeological resources. Under 30 CFR § 250.194(c) and 

30 CFR § 250.1010(c), lessees are also required to immediately notify BSEE’s Regional Director of the 

discovery of any potential archaeological resources.

Except for the projected 0-1 new gas processing facilities and 0-1 new pipeline landfalls, a CPA 

proposed action would require no new oil and gas coastal infrastructure. It is expected that archaeological 

resources would be protected through the review and approval processes of the various Federal, State, and 

local agencies involved in permitting onshore activities.

Impacts to documented and undocumented historic archaeological resources could occur as a result of 

an accidental oil spill and the associated cleanup operations. Should a spill contact a historic 

archaeological site (including submerged sites), damage might include contamination of materials, direct 

impact from oil-spill cleanup equipment, and/or looting. An additional major effect from an oil spill 

could be viewshed pollution of a historic coastal site, such as a fort or lighthouse. Although such effects 

may be temporary and reversible, cleaning oil from historic structures can be a complex, time-consuming, 

and expensive process, and the use of dispersants may result in long-term chemical contamination of 

submerged cultural heritage sites (e.g., Chin and Church, 2010). It is expected, however, that any spill 

cleanup operations would be considered a Federal action for the purposes of Section 106 of the National 

Historic Preservation Act and would be conducted in such a way as to minimize impacts to historic 

archaeological resources. A detailed impact analysis of the accidental impacts that may be associated 

with proposed CPA Lease Sales 235, 241, and 247 on historic archaeological resources can be found in 

Chapter 4.2.1.22.1.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in 

Chapter 4.2.1.22.1 of the WPA 233/CPA 231 Supplemental EIS. Detailed risk analyses of offshore oil 

spills ranging from <1,000 bbl to ≥1,000 bbl and coastal spills associated with a CPA proposed action are 

provided in Chapters 3.2.1.5, 3.2.1.6, and 3.2.1.7 of this Supplemental EIS and Chapters 3.2.1.5, 3.2.1.6, 

and 3.2.1.7 of the 2012-2017 WPA/CPA Multisale EIS. When oil is spilled in offshore areas, much of the 

oil volatilizes or is dispersed by currents, so it has a low probability of contacting coastal areas.

Impacts to documented and undocumented historic archaeological resources could occur as a result of 

an accidental oil spill and the associated cleanup operations; however, the potential for spills is low, the 

effects would generally be localized, and the cleanup efforts would be regulated. A CPA proposed action, 
Description of the Environment and Impact Analysis 4-167

therefore, is not expected to result in impacts to historic archaeological sites; however, should such 

impacts occur, unique or significant archaeological information could be lost and this impact could be 

irreversible.

Summary and Conclusion

BOEM has reexamined the analysis for historic archaeological resources presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented above. No new significant information was discovered that would alter the impact conclusion 

for historic archaeological resources presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS because the only new relevant documentation describes the survey 

procedures undertaken by Shoreline Cleanup and Assessment Technique (SCAT) teams and a summation 

of site discoveries. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

Cumulative Impacts

Background/Information 

Archaeological surveys, where required prior to an operator beginning oil and gas activities on a 

lease, are assumed to be highly effective in reducing the potential for an interaction between an impactproducing activity and a historic resource. The surveys are expected to be most effective in areas where 

there is only a thin veneer of unconsolidated Holocene sediments. In these areas, shipwreck remains are 

more likely to be exposed at the seafloor where they can be detected by sidescan sonar as well as a 

magnetometer. In areas of thicker unconsolidated sediments, shipwreck remains are more likely to be 

completely buried, with detection relying solely on magnetometry.

Of the cumulative scenario activities, those that could potentially impact historic archaeological 

resources include the OCS Program’s routine and accidental impacts; OCS sand borrowing; artificial 

Rigs-to-Reefs development; offshore LNG projects; renewable energy and alternative-use conversions; 

oil-spill response and cleanup operations; new channel dredging and maintenance dredging; State oil and 

gas activity, artificial reef development, renewable energy and alternative-use conversions; commercial 

fishing trawling; sport diving and commercial treasure hunting; and natural processes, including wave 

action and hurricanes. 

OCS Oil- and Gas-Related Impacts 

The OCS oil- and gas-related impact-producing factors that could potentially impact historic 

archaeological resources include the OCS Program’s routine and accidental impacts (refer to Chapters 

4.2.1.22.1.2 and 4.2.1.22.1.3 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.22.1 of the 

WPA 233/CPA 231 Supplemental EIS for more detail), artificial Rigs-to-Reefs development, and 

renewable energy and alternative-use conversions.

According to estimates presented in Table 3-3, between 2012 and 2051, an estimated 15,440-22,007 

exploration, delineation, development, and production wells would be drilled and 1,435-2,026 production 

platforms would be installed as a result of the OCS Program. Of this range, between 6,110 and 8,720 

exploration, delineation, production, and development wells would be drilled, and 1,210-1,720 production 

structures would be installed in water depths of 60 m (196 ft) or less. In support of a typical CPA lease 

sale, an estimated 168-329 exploration and delineation wells and 215-417 development and production 

wells would be drilled, and 35-67 production platforms would be installed (Table 3-4). Of this range, 

between 140 and 273 exploration, delineation, production, and development wells would be drilled and 

28-54 production structures would be installed in water depths of 60 m (196 ft) or less. All of the lease 

blocks in this water depth have a high potential for historic shipwrecks. The potential of an interaction 

between an MODU or platform emplacement and a historic shipwreck is greatly diminished by requisite 

site surveys, where required, but it still exists in areas where surveys have not been required in the past or 

have been acquired at insufficient transect spacing. Such an interaction could result in the loss of or 

damage to significant or unique historic resources. Archaeological surveys provide the necessary 

information to develop avoidance strategies that reduce the potential for impacts on archaeological 
4-168 Central Planning Area Lease Sales 235, 241, and 247 EIS

resources. Current archaeological survey guidance is provided in NTL 2005-G07 (“Archaeological 

Resource Surveys and Reports”) and NTL 2011-JOINT-G01 (“Revisions to the List of OCS Lease Blocks 

Requiring Archaeological Resource Surveys and Reports”), and in BOEM’s pre-seabed disturbance 

mitigation for the avoidance of archaeological resources (USDOI, BOEM, 2011).

Table 3-3 indicates that the placement of between 30,428 and 69,749 km (18,907-43,340 mi) of 

pipelines is projected in the cumulative activity area for 2012-2051. While the required archaeological 

survey minimizes the chances of impacting a historic shipwreck, there remains a possibility that a wreck 

could be impacted by pipeline emplacement. Such an interaction could result in the loss of significant or 

unique historic resources.

The setting of anchors for drilling rigs, platforms, and pipeline lay barges, and anchoring associated 

with oil and gas service-vessel trips to the OCS have the potential to impact historic wrecks. 

Archaeological surveys, when required, serve to minimize the chance of impacting historic wrecks; 

however, these surveys are not infallible and the chance of an impact from future activities does exist. 

Impacts from anchoring on a historic shipwreck have occurred in the past and may occur again. In 2004 

an anchor associated with an exploration well was dragged across the wreck of the World War II-era 

tanker Gulfstag, due in part to inadequate survey coverage of the area Such an interaction can result in 

the loss of or damage to significant or unique historic resources and the scientific information they 

contain.

The OCS sand borrowing is expected to increase in volume during the OCS cumulative activities

period. Approximately 76 million yd3 of OCS sand are liable to be accessed for coastal restorations over 

the next 5-10 years, primarily from Ship Shoal Blocks 88 and 89 and from South Pelto Blocks 12 and 13. 

For this type of bottom-disturbing activity, a preconstruction archaeological survey is required by BOEM 

for the borrow site lease. These surveys are expected to be effective at identifying potential cultural 

resources within the sand borrow area and at establishing proper dredging setback distances for these 

potential resources. No new disturbance of historic shipwrecks would be expected when these surveys 

are conducted and the setback distances adhered to.

The Rigs-to-Reefs program, offshore LNG projects, and renewable energy projects and alternativeuse conversions are expected to remain at, respectively, a steady pace of activity, to decrease, and to 

increase as competing uses of the OCS. A preconstruction archaeological survey is typically required 

before bottom-disturbing activities are permitted for new artificial reef placement areas, deepwater ports 

for LNG facilities, and newly built renewable energy facilities. Alternative-use conversions of existing 

infrastructure likely would not involve new bottom-disturbing activities; for permit applications that do 

involve new bottom-disturbing activities, a preconstruction survey would be required. No new 

disturbance of historic shipwrecks would be expected when these surveys are conducted and when proper 

setback distances of potential resources are adhered to.

Past, present, and future OCS oil and gas exploration and development would result in the deposition 

of a significant mass of steel debris on the seafloor. The loss or discard of steel debris associated with oil 

and gas exploration and development, and trawling activities could result in the masking of historic 

shipwrecks or the identification of false negatives on archaeological surveys (an anomaly that does not 

appear to be of historical significance, but actually is). Such masking of the signatures characteristic of 

historic shipwrecks may have resulted or may yet result in OCS oil- and gas-related activities in the 

cumulative activity area impacting a shipwreck containing significant or unique historic information.

The probabilities of offshore oil spills ≥1,000 bbl occurring from OCS Program activities is presented 

in Chapter 3.2.1.5.1 and Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS. Oil spills have the 

potential to impact submerged or coastal historic sites directly or indirectly by physical impacts caused by 

oil-spill cleanup operations. Table 3-23 of the 2012-2017 WPA/CPA Multisale EIS presents coastal spills

categorized by source. 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 OCS oil- and gasrelated commercial and recreational activities remain the same. Should such oil spills contact a historic 

site, the effects may be temporary and reversible; however, cleaning oil from historic structures can be a 

complex, time-consuming, and expensive process, and the use of dispersants may result in long-term 

chemical contamination of submerged cultural heritage sites (e.g., Chin and Church, 2010). Accidental 

spills as a result of a low-probability catastrophic event are discussed in Appendix B. 
Description of the Environment and Impact Analysis 4-169

Non-OCS Oil- and Gas-Related Impacts

The non-OCS oil- and gas-related impact-producing factors that could potentially impact historic 

archaeological resources include State oil and gas activity; offshore LNG projects; new channel dredging 

and maintenance dredging; State renewable energy and alternative-use conversions; State artificial reefs

and Rigs-to Reefs development; commercial fishing, sport diving, and commercial treasure hunting; and 

natural processes, including wave action and hurricanes. 

Most channel dredging occurs at the entrances to bays, harbors, and ports. These areas have a high 

potential for historic shipwrecks, and the greatest concentrations of historic wrecks are likely associated 

with these features (Pearson et al., 2003). It is reasonable to assume that significant or unique historic 

archaeological information has been lost as a result of past channel dredging activity. In many areas, 

COE requires remote-sensing surveys prior to dredging activities to minimize such impacts. Maintenance 

dredging takes place in existing, often well-used, and marked seaways and transit corridors. Any historic 

wrecks within maintenance dredged areas would have been already disturbed or their historical context 

destroyed. Routine maintenance dredging, as an ongoing activity in heavily trafficked channels, is not 

likely to result in any new disturbance or disruption to historic wrecks.

Within State waters, oil- and gas-related activities, sand borrow projects, renewable energy projects, 

artificial reef creation, and alternative-use conversions are not under the jurisdiction of BOEM with 

respect to the archaeological resource protection requirements of the National Historic Preservation Act 

(NHPA). Under the NHPA, other Federal agencies, such as COE, which issues permits associated with 

pipelines and sand borrow projects in State waters, are responsible for taking into consideration the 

effects of activities permitted by such agencies on archaeological resources. Therefore, the impacts that 

might occur to archaeological resources by pipeline construction, sand borrowing, renewable energy 

infrastructure, or alternative-use conversions within State waters should be mitigated under the 

requirements of the NHPA. Any activities resulting in new bottom disturbances may require a preclearance archaeological survey at the discretion of the State or lead Federal agency.

Past, present, and future oil and gas exploration and development within State waters, renewable 

energy development, LNG processing facilities, and commercial fishing trawling would also result in the 

deposition of tons of steel debris on the seafloor. Modern marine debris associated with these activities 

may mask the magnetic signatures of historic shipwrecks, particularly in areas that were developed prior 

to requiring archaeological surveys. Such masking of the signatures characteristic of historic shipwrecks 

may have resulted or may yet result in non-OCS oil- and gas-related activities in the cumulative activity 

area impacting a shipwreck containing significant or unique historic information.

Commercial fishing trawling activity may also have a direct impact on historic shipwrecks resulting 

from contact between a wreck and trawl nets. This activity specifically would only affect the uppermost 

portions of the sediment column (Garrison et al., 1989) in water depths generally <600 ft (183 m). Many 

wooden-hulled wrecks in these areas may be buried below the expected depth of sediment column 

impacts or may already be disturbed by natural factors that have minimized the wreck’s archaeological 

context.

Sport diving, which is generally restricted to water depths <130 ft (40 m), and commercial treasure 

hunting are significant factors in the loss of historic data from wreck sites. Efforts to educate sport divers 

and to foster the protection of historic shipwrecks, such as those of the Florida Keys National Marine 

Sanctuary and the Florida Public Archaeology Network, serve to lessen these potential impacts. While 

commercial treasure hunters generally impact wrecks with intrinsic monetary value, sport divers may 

collect souvenirs from all types of wrecks within their diving limits. Since the extent of these activities is 

unknown, the impact cannot be quantified. A Spanish war vessel, El Cazador, was discovered in the 

CPA; it contained a large amount of silver coins and has been impacted by treasure hunting salvage 

operations (McLaughlin, 1995). Another vessel, the 19th-century steamship New York, was discovered in 

the WPA in the 1990’s. This wreck has also been subjected to extensive impacts related to treasure 

hunting salvage of coins, shipboard artifacts and personal artifacts (Gearhart et al., 2011). The historic 

data available from these wrecks and from other wrecks that have been impacted by treasure hunters and 

sport divers represent a localized significant or unique loss of archaeological information.

Shipwrecks and other historic archaeological sites in shallow waters may be eroded and dispersed by 

normal coastal wave activity, which is intensified during hurricanes and tropical storms. On average, 

15-20 hurricanes make landfall along the northern Gulf Coast per decade. Shipwrecks in shallow waters 

are exposed to a greatly intensified, longshore current during tropical storms (Clausen and Arnold, 1975). 
4-170 Central Planning Area Lease Sales 235, 241, and 247 EIS

Under such conditions, it is highly likely that artifacts (e.g., ceramics and glass) would be dispersed. 

Some of the original information contained in the site would be lost in this process, but a significant 

amount of information would also remain. Overall, a significant loss of data from historic sites has 

probably occurred, and will continue to occur, in the northwestern Gulf from the effects of tropical 

storms. Some of the data lost have most likely been significant or unique. Hurricane-induced damage to 

shipwrecks sunk as artificial reefs have been observed in over 200 ft (61 m) of water (Gearhart et al., 

2011).

Summary and Conclusion

Several impact-producing factors may threaten historic archaeological resources, all related to 

bottom-disturbing activities. An impact could result from contact between a historic shipwreck and OCS 

Program or State oil and gas activities (i.e., pipeline and platform installations, drilling rig emplacement 

and operation, dredging, anchoring activities, structure removal, and site clearance). Bottom-disturbing 

activities on the OCS and within State waters also may include maintenance dredging, sand borrowing, 

transported artificial reef emplacement, liquefied natural gas facility construction, and renewable energy 

facility construction. With the exception of maintenance dredging, preconstruction surveys may be 

required by BOEM or the lead Federal permitting agency. Archaeological surveys, where required prior 

to an operator beginning oil and gas activities on a lease, are assumed to be highly effective in reducing 

the potential for an interaction between an impact-producing activity and a historic resource. Impacts 

resulting from the imperfect knowledge of the location of historic resources, however, may still occur in 

areas where a high-resolution survey is conducted at insufficient transect spacing or not at all. The loss or 

discard of steel debris associated with oil and gas exploration and development and trawling activities 

could result in the masking of historic shipwrecks or the identification of false negatives on 

archaeological surveys (an anomaly that does not appear to be of historical significance, but actually is).

Non-OCS oil- and gas-related factors that may impact historic shipwrecks include maintenance 

dredging, commercial fishing trawling, sport-diving and treasure hunting, and hurricanes and tropical 

storms. It is expected that these elements have impacted and will continue to impact historic period 

shipwrecks on the shelf where such activities occur, and independent of a CPA lease sale.

Development onshore as a result of a CPA proposed action could result in the direct physical contact 

between a historic site and pipeline trenching. Such activities are not under the jurisdiction of BOEM 

with respect to the archaeological resource protection requirements of the NHPA and would instead be 

the responsibility of other Federal agencies, which issue permits associated with pipelines in State waters. 

It is assumed that archaeological investigations prior to construction would serve to satisfy the lead 

agency’s NHPA requirements and to mitigate these potential impacts. 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. Oil spills have the potential to impact coastal historic sites directly or indirectly by 

physical impacts caused by oil-spill cleanup operations. The number and most likely spill sizes to occur 

in coastal waters in the future are expected to resemble the patterns that have occurred in the past. 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). Damage to or 

loss of significant or unique historic archaeological information from commercial fisheries (i.e., trawling) 

is highly likely in water depths <600 ft (183 m) (Foley, 2010).

The effects of the various impact-producing factors discussed in this analysis have likely resulted in 

the localized loss of significant or unique historic archaeological information. In the case of factors 

related to OCS Program activities within the cumulative activity area, it is reasonable to assume that most 

impacts would have occurred where development occurred prior to any archaeological survey 

requirements. The incremental contribution of a CPA proposed action is expected to be very small due to 

the efficacy of remote-sensing surveys and archaeological reports, where required. Future OCS Program 

activities and the bottom-disturbing activities permitted by BOEM and other agencies may require 

preconstruction archaeological surveys that, when completed, are highly effective in identifying bottom 

anomalies that could be avoided or investigated before bottom-disturbing activities begin. When surveys 

are not required, it is impossible to anticipate what might be imbedded in or lying directly on the seafloor, 

and impacts to these sites are likely to be major in scale. Despite diligence in site-clearance survey 
Description of the Environment and Impact Analysis 4-171

reviews, there is still the possibility of an unanticipated interaction between bottom-disturbing activity 

(i.e., rig emplacement, pipeline trenching, anchoring, and other ancillary activities) and a historic 

shipwreck.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources, as well as interviews with Larry Murphy, Historic 

Properties Specialist Officer for the Section 106 response to the Deepwater Horizon explosion, oil spill, 

and response, and Dan Odess, DOI Consulting Archaeologist, were conducted to determine the 

availability of recent information. Various Internet sources were examined to assess recent information

regarding impacts to archaeological resources or potential new threats to archaeological resources that 

may be pertinent to the CPA. These Internet sources included various online indexes to periodical 

literature, such as EBSCO Online (http://web.ebscohost.com), JSTOR (http://www.jstor.org/), the 

National Technical Information Service’s National Technical Reports Library (https://ntrlr3.ntis.gov), and 

ScienceDirect (http://www.sciencedirect.com/). A 2011 interim report describes activities to support 

response activities related to the Deepwater Horizon explosion, oil spill, and response and to evaluate the 

impact or potential impact of the event and subsequent cleanup operations to previously recorded and 

unidentified cultural resources. This cultural resources undertaking involves both Federal and State 

agencies within the States of Louisiana, Mississippi, Alabama, and Florida. The cultural resources 

investigation for the Deepwater Horizon explosion, oil spill, and response was managed as a component 

of the SCAT process, and archaeologists have been involved throughout this process. Cultural resources 

investigations utilized a combination of pedestrian surveys, shovel testing, auger test sampling, and trench 

sampling. In addition, archaeological and Tribal monitors have been embedded with all cleanup 

operations. This report summarizes the findings of the pre-field investigations, field surveys, and cleanup 

monitoring associated with the response to the Deepwater Horizon explosion and oil spill through 

March 31, 2011 (HDR, 2011).

In April 2012, BOEM, working with NOAA’s Office of Ocean Exploration and Research from the 

research vessel Okeanos Explorer, investigated a sonar target reported by Shell Oil in over 4,000 ft 

(1,200 m) of water in an area of the CPA almost 200 mi (320 km) offshore where an archaeological 

survey had previously not been required. The target proved to be the intact remains of an armed sailing 

ship dating from around 1790 to 1840. The following year in July 2013, BOEM participated in an 

expedition that identified two additional shipwrecks from the same time period less than 4 mi (6 km) 

away that also had been reported by Shell Oil as sonar targets. These discoveries highlight situations 

where site-specific surveys prior to bottom-disturbing activities may mitigate potential impacts, and they 

reinforce BOEM’s need to acquire imagery of the seafloor in order to make informed management 

decisions during its NEPA analyses.

Although there is incomplete or unavailable information on reasonably foreseeable impacts to historic 

archaeological resources, BOEM feels that this information is not essential to a reasoned choice among 

alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. The locations of many archaeological resources remain unknown, some 

resources are buried under heavy sedimentation and therefore likely protected from many impacts, and 

archaeological surveys, where required, are expected to be highly effective in identifying resources to 

allow for protection of the resource during oil and gas activities. Nevertheless, this incomplete or 

unavailable information is not likely to be available within the timeline contemplated in the NEPA

analysis of this Supplemental EIS. Hundreds of known historic archaeological resources are scattered 

throughout the Gulf of Mexico and thousands more may exist, but their locations are unknown to date. 

The costs of a Gulfwide study would be exorbitant, and it could take years before data confirming the 

presence of additional historic archaeological resources and the status of each could be compiled and 

analyzed. In place of this incomplete or unavailable information, BOEM’s subject-matter experts have 

included what credible scientific information is available and applied it using accepted scientific 

methodologies as noted herein and in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS.
4-172 Central Planning Area Lease Sales 235, 241, and 247 EIS

4.1.1.22.2. Prehistoric

BOEM has reexamined the analysis for prehistoric archaeological resources presented in the 2012-

2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional 

information presented below. No new significant information was discovered that would alter the impact 

conclusion for prehistoric archaeological resources presented in the 2012-2017 WPA/CPA Multisale EIS. 

The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the 

WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

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

the CPA proposed action are presented in Chapters 4.2.1.22.2.2 and 4.2.1.22.2.3 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.22.2 of the WPA 

233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental contribution to the cumulative 

impacts is presented below. Any new information that has become available since those documents were 

published is presented below.

A detailed description of prehistoric archaeological resources can be found in Chapter 4.2.1.22.2.1 of 

the 2012-2017 WPA/CPA Multisale EIS, and updated information provided in Chapter 4.2.1.22.2 of the 

WPA 233/CPA 231 Supplemental EIS.

Impacts of Routine and Accidental Events

Offshore development as a result of a CPA proposed action could result in an interaction between a 

drilling rig, platform, pipeline, dredging activity, or anchors and an inundated prehistoric site. This direct 

physical contact with a site could destroy fragile artifacts or site features and could disturb artifact 

provenance and site stratigraphy. The result would be the loss of archaeological data on prehistoric 

migrations, settlement patterns, subsistence strategies, and archaeological contacts for North America, 

Central America, South America, and the Caribbean. A detailed impact analysis of the routine impacts of 

OCS activities that may be associated with proposed CPA Lease Sales 235, 241, and 247 on prehistoric 

archaeological resources can be found in Chapter 4.2.1.22.2.2 of the 2012-2017 WPA/CPA Multisale 

EIS, and updated information is provided in Chapter 4.2.1.22.2 of the WPA 233/CPA 231 Supplemental 

EIS.

Prehistoric archaeological sites are thought to be preserved shoreward of the 45-m (148-ft) 

bathymetric contour, where the Gulf of Mexico continental shelf was exposed during the Late 

Pleistocene. The greatest potential impact to an archaeological resource as a result of a CPA proposed 

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

emplacement, dredging, pipeline emplacement) and a prehistoric site. Archaeological surveys provide the 

necessary information to develop avoidance strategies that reduce the potential for impacts on 

archaeological resources.

Archaeological survey and archaeological clearance of sites, where required prior to an operator 

beginning oil and gas activities on a lease, are expected to be somewhat effective at identifying 

submerged landforms that could support possible archaeological sites. The NTL 2005-G07 suggests a 

300-m (984-ft) line spacing for remote-sensing surveys of leases within areas having a high potential for 

prehistoric sites. While surveys, where required, provide a reduction in the potential for a damaging 

interaction between an impact-producing factor and a prehistoric archaeological site, there is a possibility 

of an OCS activity contacting an archaeological site because of an insufficiently dense survey grid. 

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

information.

Impacts to documented and undocumented prehistoric archaeological resources could occur as a 

result of an accidental oil spill and the associated cleanup operations. Should a spill contact a prehistoric 

archaeological site, damage might include loss of radiocarbon-dating potential, direct impact from oilspill cleanup equipment, and/or looting. Previously unrecorded sites could be impacted by oil-spill 

cleanup operations on beaches. Detailed risk analyses of offshore oil spills ranging from <1,000 bbl to 

≥1,000 bbl and coastal spills that may be associated with a CPA proposed action is provided in Chapters 

3.2.1.5, 3.2.1.6, and 3.2.1.7 of this Supplemental EIS and Chapters 3.2.1.5, 3.2.1.6 and 3.2.1.7 of the 

2012-2017 WPA/CPA Multisale EIS. When oil is spilled in offshore areas, much of the oil volatilizes or 

is dispersed by currents, so it has a low probability of contacting coastal and barrier island prehistoric 
Description of the Environment and Impact Analysis 4-173

sites as a result of a CPA proposed action. A CPA proposed action, therefore, is not expected to result in 

impacts to prehistoric archaeological sites.

Oil spills resulting from a well blowout in the CPA and related spill-response activities have the 

potential to impact cultural resources near the spill site and landfall areas. A detailed impact analysis of 

the accidental impacts OCS activities that may be associated with proposed CPA Lease Sales 235, 241, 

and 247 on prehistoric archaeological resources can be found in Chapter 4.2.1.22.2.3 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.22.2 of the WPA

233/CPA 231 Supplemental EIS.

Summary and Conclusion

BOEM has reexamined the analysis for prehistoric archaeological resources presented in the 2012-

2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional 

information presented above. No new significant information was discovered that would alter the impact 

conclusion for prehistoric archaeological resources presented in the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS because the only new relevant document describes the survey 

procedures undertaken by SCAT teams and a summation of site discoveries. The analysis and potential 

impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 

Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Information 

Prehistoric archaeological sites are thought potentially to be preserved shoreward of the 45-m (148-ft) 

bathymetric contour, where the Gulf of Mexico continental shelf was exposed during the Late 

Pleistocene. Archaeological surveys, where required prior to an operator beginning oil and gas activities 

on a lease, are expected to be somewhat effective at identifying submerged landforms that could support 

possible prehistoric archaeological sites. While surveys provide a reduction in the potential for a 

damaging interaction between an impact-producing factor and a prehistoric archaeological site, there is 

still a possibility of an OCS oil- and gas-related activity contacting an archaeological site. Should such 

impacts occur, there could be damage to or loss of significant and/or unique archaeological information.

Of the cumulative scenario activities, those that could potentially impact prehistoric archaeological 

resources include the OCS Program’s routine and accidental impacts; OCS sand borrowing; artificial 

Rigs-to-Reef development; renewable energy and alternative-use conversions; oil-spill response and 

cleanup operations; new channel dredging and maintenance dredging; State oil and gas activity, artificial 

reef development, renewable energy and alternative-use conversions; commercial fishing trawling; and 

natural processes, including wave action and hurricanes. 

OCS Oil- and Gas-Related Impacts 

The OCS oil- and gas-related impact-producing factors that could potentially impact prehistoric 

archaeological resources include the OCS Program’s routine and accidental impacts (refer to Chapters 

4.2.1.22.2.2 and 4.2.1.22.2.3 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.22.2 of the 

WPA 233/CPA 231 Supplemental EIS for more detail); renewable energy and alternative-use conversion; 

and artificial Rigs-to-Reefs development.

According to estimates presented in Table 3-3, between 2012 and 2051, an estimated 15,440-22,007 

exploration, delineation, development, and production wells would be drilled, and 1,435-2,026 production 

platforms would be installed as a result of the OCS Program. Of this range, between 6,110 and 8,720 

exploration, delineation, production, and development wells would be drilled and 1,210-1,720 production 

structures would be installed in water depths of 60 m (196 ft) or less. In support of a typical CPA lease 

sale, an estimated 168-329 exploration and delineation wells and 215-417 development and production 

wells would be drilled, and 35-67 production platforms would be installed (Table 3-4). Of this range, 

between 140 and 273 exploration, delineation, production, and development wells would be drilled, and 

28-54 production structures would be installed in water depths of 60 m (196 ft) or less. Relative sea-level 

curves for the Gulf of Mexico indicate there is no potential for the occurrence of prehistoric 

archaeological sites in water depths >60 m (196 ft). Archaeological surveys are assumed to be highly 
4-174 Central Planning Area Lease Sales 235, 241, and 247 EIS

effective in reducing the potential for an interaction between an impact-producing activity and a 

prehistoric resource by providing the necessary information to develop avoidance strategies. The 

potential of an interaction between rig or platform emplacement and a prehistoric site is diminished by the 

survey, but it still exists in areas where surveys have not been required in the past or have been acquired 

at insufficient transect spacing. Such an interaction could result in the loss of or damage to significant or 

unique prehistoric information. Archaeological surveys provide the necessary information to develop 

avoidance strategies that reduce the potential for impacts on archaeological resources. Current 

archaeological survey guidance is provided in NTL 2005-G07 (“Archaeological Resource Surveys and 

Reports”) and NTL 2011-JOINT-G01 (“Revisions to the List of OCS Lease Blocks Requiring 

Archaeological Resource Surveys and Reports”), and in BOEM’s pre-seabed disturbance mitigation for 

the avoidance of archaeological resources (USDOI, BOEM, 2011).

Table 3-3 indicates that the placement of between 30,428 and 69,749 km (18,907 and 43,340 mi) of 

pipelines is projected in the cumulative activity area for 2012-2051. While archaeological surveys 

minimize the chances of impacting a prehistoric site, there remains a possibility that a site could be 

impacted by pipeline emplacement. Such an interaction would result in the loss of significant or unique 

archaeological information.

The setting of anchors for drilling rigs, platforms, and pipeline lay barges, and anchoring associated 

with oil and gas service-vessel trips to the OCS have the potential to impact shallowly buried prehistoric 

sites in water depths <60 m (197 ft). Archaeological surveys minimize the chance of impacting these 

sites; however, these surveys are not seen as infallible, and the chance of an impact from future activities 

exists. Impacts from anchoring on a prehistoric site may have occurred. Such an interaction could result 

in the loss of significant or unique archaeological information.

The OCS sand borrowing is expected increase in volume during the OCS cumulative activities period. 

Approximately 76 million yd3 (58 million m3

) of OCS sand are liable to be accessed for coastal 

restorations over the next 5-10 years, primarily from Ship Shoal Blocks 88 and 89 and from South Pelto 

Blocks 12 and 13. For these types of bottom-disturbing activities, a preconstruction archaeological 

survey is required by BOEM for the borrow site lease. These surveys are expected to be effective at 

identifying potential cultural resources within the sand borrow area and at establishing proper dredging 

setback distances for these potential resources. No new disturbance of prehistoric archaeological

resources would be expected when these surveys are conducted and the setback distances adhered to.

The Rigs-to-Reefs program, renewable energy projects, and alternative-use conversions are expected 

to remain at, respectively, a steady pace of activity, to decrease, and to increase as competing uses of the 

OCS. A preconstruction archaeological survey is typically required before bottom-disturbing activities 

are permitted for new artificial reef placement areas and newly built renewable energy facilities. 

Alternative-use conversions of existing infrastructure likely would not involve new bottom-disturbing 

activities; for permit applications that do involve new bottom-disturbing activities, a preconstruction 

survey would be required. No new disturbance of prehistoric sites would be expected when these surveys 

are conducted and when proper setback distances of potential resources are adhered to.

The probabilities of offshore oil spills ≥1,000 bbl occurring from the OCS Program in the cumulative 

activity area are presented in Chapter 3.2.1.5.1 and Table 3-12 of the 2012-2017 WPA/CPA Multisale 

EIS. Oil spills have the potential to impact coastal prehistoric sites directly or indirectly by physical 

impacts caused by oil-spill cleanup operations. Coastal oil-spill scenario numbers are presented in Table 

3-23 of the 2012-2017 WPA/CPA Multisale EIS and are categorized by source. 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. There is a small possibility of these spills contacting a prehistoric site. The impacts caused by 

oil spills to coastal prehistoric archaeological resources can severely distort information relating to the age 

of the site. Contamination of the organic site materials by hydrocarbons can make radiocarbon dating of 

the site more difficult or even impossible. This loss might be partially ameliorated by using artifact 

seriation or other relative dating techniques. Coastal prehistoric sites might also suffer direct impact from 

oil-spill cleanup operations as well as looting resulting from interactions between persons involved in 

cleanup operations and unrecorded prehistoric sites. Interaction between oil-spill cleanup equipment or 

personnel and a site could destroy fragile artifacts or disturb site context, possibly resulting in the loss of 

information on the prehistory of North America and the Gulf Coast region. Some coastal sites may 

contain significant or unique information. Accidental spills as a result of a low-probability catastrophic 

event are discussed in Appendix B. 
Description of the Environment and Impact Analysis 4-175

Non-OCS Oil- and Gas-Related Impacts

The non-OCS oil- and gas-related impact-producing factors that could potentially impact prehistoric 

archaeological resources include State oil and gas activity, new channel dredging and maintenance 

dredging, State renewable energy and alternative-use conversions, State artificial reefs and Rigs-to-Reefs 

development, OCS sand borrowing, offshore LNG projects, commercial fishing, and natural processes, 

including wave action and hurricanes. 

Most channel dredging occurs at the entrances to bays, harbors, and ports. Bay and river margins 

have a high potential for the occurrence and preservation of prehistoric sites. Prior channel dredging has 

disturbed buried and/or inundated prehistoric archaeological sites in the coastal plain of the Gulf of 

Mexico. It is assumed that some of the sites and associated archaeological data were unique or 

significant. In many areas, regulatory agencies require surveys prior to dredging activities to minimize 

such impacts. Maintenance dredging takes place in existing, often well-used, and marked seaways and 

transit corridors. Any prehistoric sites within maintenance dredged areas would have been already 

disturbed or their historical context destroyed. Routine maintenance dredging, as an ongoing activity in 

heavily trafficked channels, is not likely to result in any new disturbance or disruption to prehistoric sites.

Within State waters, oil- and gas-related activities, sand borrow projects, renewable energy projects, 

artificial reef creation, and alternative-use conversions are not under the jurisdiction of BOEM with 

respect to the archaeological resource protection requirements of the NHPA. Under the NHPA, other 

Federal agencies, such as COE, which issues permits associated with pipelines and sand borrow projects 

in State waters, are responsible for taking into consideration the effects of activities permitted by such 

agencies on archaeological resources. Therefore, the impacts that might occur to prehistoric 

archaeological resources by pipeline construction, sand borrowing, LNG processing facility construction, 

State oil and gas infrastructure construction, renewable energy infrastructure construction, or alternativeuse conversions within State waters should be mitigated under the requirements of the NHPA. Any 

activities resulting in new bottom disturbances may require a pre-clearance archaeological survey at the 

discretion of the State or lead Federal agency.

Commercial fishing trawling activity may also have an impact on prehistoric archaeological sites in 

State waters, resulting from contact between a site and trawl nets. This activity specifically would only 

affect the uppermost portions of the sediment column (Garrison et al., 1989). Most, if not all, of the 

prehistoric resources in these areas may be buried below the expected depth of sediment column impacts 

or would otherwise already be disturbed by natural factors that have minimized the resources’ 

archaeological context through wave-based erosion and redeposition.

Submerged prehistoric archaeological sites will be eroded and dispersed by normal coastal wave 

activity, which is intensified during hurricanes and tropical storms. Over 100 hurricanes have made 

landfalls along the northern Gulf of Mexico coast from the Florida Panhandle to Texas over the past 

century (Liu and Fearn, 2000; Keim and Muller, 2009). Prehistoric sites in shallow waters and on coastal 

beaches are exposed to the destructive effects of wave action and scouring currents. Under such 

conditions, it is highly likely that artifacts would be dispersed and the site context disturbed. Some of the 

original information contained in the site would be lost in this process. Overall, loss of data from 

prehistoric sites has probably occurred, and will continue to occur, in the northeastern Gulf from the 

effects of tropical storms.

Summary and Conclusion

Several impact-producing factors may threaten prehistoric archaeological resources of the Gulf of 

Mexico. An impact could result from contact between proposed oil and gas activities (including pipeline 

construction, platform installation, drilling rig emplacement and operation, dredging, and anchoring 

activities) and an oil spill and subsequent cleanup efforts. Each of these activities or events could damage 

and destroy a prehistoric archaeological site located on the continental shelf. Archaeological surveys, 

where required, and the resulting archaeological analyses completed prior to an operator beginning oil 

and gas activities on a lease are expected to be highly effective at identifying possible prehistoric sites. 

The OCS development has possibly impacted sites containing significant or unique prehistoric

information in areas where surveys have not been required in the past or have been acquired at 

insufficient transect spacing. It is also possible that, even with current survey methods, prehistoric 

archaeological sites may be missed. No significant new information was found at this time that would 
4-176 Central Planning Area Lease Sales 235, 241, and 247 EIS

alter the overall conclusion that cumulative impacts on prehistoric archaeological sites associated with a 

CPA proposed action is expected to be minimal. Should an oil spill occur and contact a coastal 

prehistoric site, loss of significant or unique information could result. Oil spills have the potential to 

impact coastal prehistoric sites directly or indirectly by physical impacts caused by oil-spill cleanup 

operations.

The initial dredging of ports and navigation channels and tropical storms are assumed to have caused 

the localized loss of significant or unique archaeological information.

Onshore development as a result of the OCS Program could result in the direct physical contact 

between a prehistoric site and new facility construction and pipeline trenching. It is assumed that 

archaeological investigations prior to construction would serve to mitigate these potential impacts.

The shallow depth of sediment disturbance caused by commercial fisheries activities (trawling) is not 

expected to exceed that portion of the sediments that have been disturbed by wave-generated forces.

The effects of the various impact-producing factors discussed in this analysis have likely resulted in 

localized losses of significant or unique prehistoric archaeological information. In the case of factors 

related to OCS Program activities in the cumulative activity area, it is reasonable to assume that most 

impacts have occurred in areas where surveys have not been required in the past or have been acquired at 

insufficient transect spacing. The incremental contribution of a CPA proposed action is expected to be 

very small due to the efficacy of the required remote-sensing survey and concomitant archaeological 

report and clearance.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of Internet information sources, as well as interviews with Larry Murphy, Historic 

Properties Specialist Officer for the Section 106 response to the Deepwater Horizon explosion, oil spill, 

and response, and Dan Odess, DOI Consulting Archaeologist, were conducted to determine the 

availability of recent information. Various Internet sources were examined to assess recent information 

regarding impacts to archaeological resources or potential new threats to archaeological resources that 

may be pertinent to the CPA. These Internet sources included various online indexes to periodical 

literature such as EBSCO Online (http://web.ebscohost.com), JSTOR (http://www.jstor.org/), the 

National Technical Information Service’s National Technical Reports Library (https://ntrlr3.ntis.gov), and 

ScienceDirect (http://www.sciencedirect.com/). A 2011 interim report describes activities to support 

response activities related to the Deepwater Horizon explosion, oil spill, and response and to evaluate the 

impact or potential impact of the event and subsequent cleanup operations to previously recorded and 

unidentified cultural resources. This cultural resources undertaking involves both Federal and State 

agencies within the States of Louisiana, Mississippi, Alabama, and Florida. The cultural resources 

investigation for the Deepwater Horizon explosion, oil spill, and response was managed as a component 

of the SCAT process, and archaeologists have been involved throughout the SCAT process. Cultural 

resources investigations utilized a combination of pedestrian surveys, shovel testing, auger test sampling, 

and trench sampling. In addition, archaeological and Tribal monitors have been embedded with all 

cleanup operations. This report summarizes the findings of the pre-field investigations, field surveys, and 

cleanup monitoring associated with the response to the Deepwater Horizon explosion and oil spill, up 

until March 31, 2011 (HDR, 2011).

Although there is incomplete or unavailable information on reasonably foreseeable impacts to 

prehistoric archaeological resources, BOEM feels that this information is not essential to a reasoned 

choice among alternatives for the reasons stated herein and in the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS. The locations of many prehistoric archaeological resources 

remain unknown, and those that have been identified are subject to Federal and State protections. 

Nevertheless, this incomplete or unavailable information is not likely to be available within the timeline 

contemplated in the NEPA analysis of this Supplemental EIS. There are numerous prehistoric 

archaeological resources scattered throughout the Gulf of Mexico and more may exist, but their locations 

and conditions are unknown to date. The costs of a Gulfwide study would be exorbitant and it could take 

years before data confirming the presence of additional prehistoric archaeological resources and the status 

of each could be compiled and analyzed. In place of this incomplete or unavailable information, BOEM’s 

subject-matter experts have included what credibly scientific information is available and applied it using 
Description of the Environment and Impact Analysis 4-177

accepted scientific methodologies as noted herein and in the 2012-2017 WPA/CPA Multisale EIS and 

WPA 233/CPA 231 Supplemental EIS.

4.1.1.23.Human Resources and Land Use

4.1.1.23.1. Land Use and Coastal Infrastructure

BOEM has reexamined the analysis for land use and coastal infrastructure presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented below. No new significant information was discovered that would alter the impact conclusion 

for land use and coastal infrastructure presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 

WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for 

proposed CPA Lease Sales 235, 241, and 247.

A detailed description of land use and coastal infrastructure can be found in Chapter 4.2.1.23.1.1 of 

the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.23.1 of 

the WPA 233/CPA 231 Supplemental EIS. The full analyses of the potential impacts of routine activities 

and accidental events associated with a CPA proposed action are presented in Chapters 4.2.1.23.1.2 and 

4.2.1.23.1.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 

4.2.1.23.1 of the WPA 233/CPA 231 Supplemental EIS. A CPA proposed action’s incremental 

contribution to the cumulative impacts is presented below. Any new information that has become 

available since those documents were published is presented below.

Impacts of Routine and Accidental Events

Many of the impacts of the Deepwater Horizon explosion, oil spill, and response to land use and 

infrastructure have been temporary and short-term, such as the ship decontamination sites and the waste 

staging areas established in the immediate aftermath of the Deepwater Horizon explosion, oil spill, and 

response (USDOT, Bureau of Transportation Statistics, 2010). These indirect effects on infrastructure 

had a short-term impact on the industry, and development drilling activity is expected to grow as several 

projects go online. Gulf of Mexico OCS oil production averaged 1.27 MMbbl of oil per day in 2013, 

which is unchanged from 2012. The Energy Information Administration forecasts GOM production of 

1.38 MMbbl of oil per day in 2014 and 1.59 MMbbl of oil per day in 2015. Production growth in 2014 

comes from eight projects expected to come online: Jack; St. Malo; Entrada; Big Foot; Tubular Bells; 

Atlantis Phase 2; Hadrian South; and Lucius. Further production growth in 2015 comes from an 

additional 10 projects: Axe; Cardamom Deep; Dalmatian; Deimos South; Kodiak; Pony; Samurai; West 

Boreas; Winter; and Mars B (USDOE, Energy Information Administration, 2014). In the future, the longterm impacts of the Deepwater Horizon explosion, oil spill, and response will be clearer as time allows 

the production of peer-reviewed research and targeted studies that determine those impacts. The 

Deepwater Horizon explosion (and subsequent oil spill and response) was a low-probability catastrophic 

event. Many non-OCS oil- and gas-related factors contribute substantially to the baseline conditions for 

existing land use and coastal infrastructure, including, but not limited to, housing and other residential 

developments; the development of private and publicly owned recreational facilities; the construction and 

maintenance of industrial facilities and transportation systems; urbanization; city planning and zoning; 

changes to public facilities such as water, sewer, educational, and health facilities; changes to military 

bases and reserves; changes in population density; changes in State and Federal land use regulations; and 

changes in non-OCS oil- and gas-related demands for water transportation systems and ports.

The impacts of routine events associated with a CPA-proposed action are expected to remain at 

historic activity levels. The OCS oil- and gas-related infrastructure has developed over many decades and 

is an extensive and mature system that provides support for offshore activities. The expansive presence 

of this coastal infrastructure is the result of long-term industry trends, and it is not subject to rapid 

fluctuations. Relatively low operating costs in the Gulf of Mexico and a stable regulatory regime make 

the region both a more profitable and a more stable operating environment for service contractors than 

places such as Brazil and Africa (Bloomberg, 2013). BOEM projects 0-1 new gas processing facilities 

and 0-1 new pipeline landfalls for a CPA proposed action. However, based on the most current 

information available, there is only a very slim chance that either would result from a CPA proposed 

action; and, if a new, greenfield gas processing facility or pipeline landfall were to result, it would likely 
4-178 Central Planning Area Lease Sales 235, 241, and 247 EIS

occur toward the end of the 40-year analysis period. The likelihood of a newbuild gas processing facility 

or pipeline landfall is much closer to zero than to one (Dismukes, official communication, 2013b). 

Because of the current near zero estimates for a pipeline landfall and gas processing facility construction, 

the routine activities associated with a CPA proposed action would have little effect on land use. BOEM 

anticipates that there would be maintenance dredging of navigation channels, provided funding is 

appropriated, in support of routine activity at services bases as a result of a CPA proposed action. In 

regard to land use and infrastructure, it does not appear that there would be adverse impacts from routine 

events associated with a CPA proposed action.

Accidental events (impact-producing factors) associated with a CPA proposed action that could affect 

land use and coastal infrastructure include, but are not limited to, oil spills, vessel collisions, and 

chemical/drilling-fluid spills. Accidental events associated with a CPA proposed action would occur at 

differing levels of severity, based in part on the location and size of event. The Deepwater Horizon

explosion, oil spill, and response resulted in the implementation of new drilling and environmental 

safeguards adopted by industry. These new safeguards have reduced the probability of a low- probability 

catastrophic spill, which is not reasonably foreseeable and not part of a CPA proposed action. Such lowprobability catastrophic events should be distinguished from accidental events that are smaller in scale 

and that occur more frequently. A detailed impact analysis of the accidental impacts that may be 

associated with proposed CPA Lease Sales 235, 241, and 247 on land use and coastal infrastructure can 

be found in Chapter 4.2.1.23.1.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.2.1.23.1 of the WPA 233/CPA 231 Supplemental EIS.

Summary and Conclusion

BOEM has reexamined the analysis for land use and coastal infrastructure presented in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information 

presented above. BOEM has determined that the additional information does not alter the impact 

conclusion for land use and coastal infrastructure because the plans to build the new gas-to-liquids facility 

are very preliminary and are dependent upon not only the outcome of the 18-month feasibility study but 

also because of future fluctuations in the natural gas supply market. Therefore, the analysis and potential 

impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 

Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

The cumulative analysis considers impacts that may result from a CPA proposed action within the 

context of OCS oil- and gas-related and non-OCS oil- and gas-related impacts, and future OCS lease 

sales. The non-OCS oil- and gas-related factors consist of prior, current, and future OCS lease sales, as 

well as other impact-producing factors not related to the OCS oil and gas leasing program. The OCS oiland gas-related impacts include a proposed action and the OCS Program, onshore waste disposal, and the 

Deepwater Horizon explosion, oil spill, and response. Non-OCS oil- and gas-related impacts include 

State oil and gas activity, downstream activities, coastal erosion and subsidence, and coastal storms. 

Many non-OCS oil- and gas-related factors contribute substantially to the cumulative impacts to land use

and coastal infrastructure, including the following: housing and other residential developments; the 

development of private and publicly owned recreational facilities; the construction and maintenance of 

industrial facilities and transportation systems; urbanization; city planning and zoning; changes to public 

facilities such as water, sewer, educational, and health facilities; changes to military bases and reserves; 

changes in population density; changes in State and Federal land use regulations; and changes in nonOCS oil- and gas-related demands for water transportation systems and ports. Chapter 4.2.1.23.1.1 of the 

2012-2017 WPA/CPA Multisale EIS and updated information provided Chapter 4.2.1.23.1 of the WPA 

233/CPA 231 Supplemental EIS discuss the socioeconomic analysis area, land use, and OCS oil- and gasrelated infrastructure associated with the analysis area. The vast majority of this infrastructure also 

supports oil and gas production in State waters, as well as in coastal areas onshore.

According to BOEM’s development scenario analysis, the construction of 0-1 new gas processing 

facilities would be expected to occur near the end of the 40-year life of a CPA proposed action. Most 

new pipelines would be offshore and would tie into the existing offshore pipeline infrastructure. 
Description of the Environment and Impact Analysis 4-179

According to the scenario analysis, 0-1 new pipeline landfalls would be expected to occur toward the end 

of the 40-year lifespan of a CPA proposed action. Those projections also called for no new waste 

disposal facilities due to existing excess capacity along the Gulf Coast. Research based on the analysis of 

historical data further validated BOEM’s past scenario projections of new gas processing facilities and 

new pipeline landfalls and found its projections to be conservative; that is, the actual numbers proved to 

be equal to, or less than, the projected numbers (Dismukes et al., 2007). Current scenario projections are 

also likely to be conservative (Dismukes, official communication, 2013b). 

OCS Oil- and Gas-Related Impacts 

The OCS oil- and gas-related onshore coastal infrastructure is extensive, covers a wide-ranging area, 

supports OCS development, and is owned, operated, maintained, and/or utilized by thousands of large and 

small companies. Lease sales will serve mostly to maintain ongoing activity levels associated with the 

current OCS Program. Industry will more or less maintain its current usage of infrastructure according to 

the proposed lease sale schedule. Macroeconomic shifts, such as a change in commodity prices or an 

economic upturn or downturn, will also determine future utilization of this infrastructure.

These industries cover every facet of OCS activity, including, but not limited to, the following: 

service bases; helicopter hubs; platform fabrication yards; shipbuilding and shipyards; pipecoating 

facilities and yards; refineries; gas processing facilities; LNG facilities; pipeline shore facilities, barge 

terminals and tanker port areas; coastal pipelines; coastal barging; and navigation channels.

Refer to Chapter 4.2.1.23.1.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.23.1 of 

the WPA 233/CPA 231 Supplemental EIS for a more detailed description of these infrastructure types. 

Impact-producing factors associated with a CPA proposed action that could affect land use and coastal 

infrastructure include, but are not limited to, gas processing facilities, pipeline landfalls, service bases, 

navigation channels, waste disposal facilities, oil spills, vessel collisions, and chemical/drilling-fluid 

spills. Impacts from these routine and accidental impact-producing factors are discussed above and in 

Chapters 4.2.1.23.1.2 and 4.2.1.23.1.3 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.23.1 

of the WPA 233/CPA 231 Supplemental EIS. BOEM’s staff continually monitors developments in the 

OCS onshore-related industries and will update analyses as new information becomes available.

Gas Processing Facilities

The majority of change is likely to occur from general, regional economic and demographic growth 

rather than from activities associated with current OCS and/or State offshore petroleum production or 

future planned OCS or State lease sales. BOEM’s development scenarios consider demand from both 

current and future OCS and State leases. These scenarios project 0-1 new gas processing facilities to 

result from a CPA proposed action. However, this number is derived from the estimated demand for 

future processing capacity. Given current industry practice, it is likely that few (if any) new, greenfield 

gas processing facilities would actually be constructed along the CPA. Instead, it is likely that a large 

share (and possibly all) of any additional natural gas processing capacity that is needed in the industry 

would be developed at existing facilities through future investments in expansions and/or replacement of 

depreciated capital equipment. Also, these BOEM scenario projections are conservative; that is, they 

likely overestimate the additional capacity that would be required.

Over the past several years, there has been a substantial decrease in offshore natural gas production, 

partially as a result of increasing emphasis on onshore shale gas development, which is less expensive to 

produce and provides larger per-well production opportunities and reserve growth. Also, there has been a 

trend toward more efficient gas processing facilities with greater processing capacities (Dismukes, 

2011a). For example, in Texas the average daily processing capacity per plant increased from 95 MMcf 

to 121 MMcf per day between 2004 and 2009. Louisiana, Mississippi, and Alabama also saw their perplant capacity increase, with the average capacity per plant in Mississippi more than doubling from 262 

MMcf per day to 568 MMcf per day (USDOE, Energy Information Administration, 2011a). While 

natural gas production on the OCS (shallow water) has been rapidly declining, deepwater gas production 

has been increasing, but not quickly enough to make up the difference. The U.S. Energy Information 

Administration’s Annual Energy Outlook 2013 forecasts that Gulf offshore natural gas production will 

decrease from 2.15 Tcf per day in 2012 to 1.89 Tcf per day in 2013 and to 1.79 Tcf per day in 2014 

(USDOE, Energy Information Administration, 2013b). These production trends are driven by many 
4-180 Central Planning Area Lease Sales 235, 241, and 247 EIS

factors, including price pressures arising from increasing onshore natural gas production (Humphries, 

2013). Increasing onshore shale gas development, declining offshore gas production, and the increasing 

efficiency and capacity of existing gas processing facilities are trends that have combined to lower the 

need for new gas processing facilities along the Gulf Coast. In terms of both capacity and the number of 

plants, Texas and Louisiana accounted for nearly half of all U.S. capacity and plants (USDOE, Energy 

Information Administration, 2011b). Spare capacity at existing facilities should be sufficient to satisfy 

new gas production for many years, although there remains a slim chance that a new gas processing 

facility may be needed by the end of the 40-year life of a CPA proposed action (Dismukes, official 

communication, 2013b). Any additions to, or expansions of, current facilities would also support State oil 

and gas production and, should any occur, the land in the analysis area is sufficient to handle 

development. Thus, the results of OCS and State oil and gas activities are expected to minimally alter the 

current land use of the area.

Pipeline Landfalls

BOEM analyzes the potential for new pipeline landfalls to determine the potential impacts to 

wetlands and other coastal habitats. In Chapter 3.1.2.1 of this Supplemental EIS, Chapter 3.1.2.1.6 of 

the 2012-2017 WPA/CPA Multisale EIS, and Chapter 3.1.2.1 of the WPA 233/CPA 231 Supplemental 

EIS, BOEM assumes that the majority of new Federal OCS pipelines would connect to the existing 

infrastructure in Federal and State waters and that very few would result in new pipeline landfalls. 

Therefore, BOEM projects up to one pipeline landfall for a CPA proposed action; however, it is generally 

unlikely that even one landfall would result from a CPA proposed action.

Service Bases/Ports

Service-base infrastructure supports offshore petroleum-related activities in both OCS and State 

waters. Any changes to offshore support infrastructure that occurs in the cumulative case are expected to 

be contained on available land. Service bases are industrial ports and are located in designated industrial 

parks designed with the intent to accommodate future oil and gas needs. Also, most of these are located 

in BOEM analysis areas that have strong industrial bases. Shore-based OCS and State servicing is 

expected to increase in the ports of Galveston, Texas; Port Fourchon, Louisiana; and Mobile, Alabama. 

There is sufficient land designated in commercial and industrial parks and adjacent to the Galveston port 

area. This would minimize disruption possible from port expansions to current residential and business 

use patterns.

In contrast, while Port Fourchon has land designated for future expansion, the port has a limited 

amount of waterfront land available and, because of surrounding wetlands, may face capacity constraints 

in the long term. Louisiana has the greatest rate of landloss in the Nation. A Louisiana State-sponsored 

study found that the “gradual erosion of Louisiana’s coast may force the oil and gas industry to interrupt, 

postpone, or permanently delay the production and transportation of oil and gas products” (Richardson 

and Scott, 2004). It is unknown how current subsidence and erosion is impacting industry or whether 

industry is making plans to mitigate current or future impacts. BOEM will continue to monitor industry 

and its infrastructure footprint over time to document short- and long-term impacts of continued landloss. 

For a more detailed discussion on deltaic landloss, refer to Chapter 4.1.1.4. Port Fourchon serves as the 

primary support base for over 90 percent of existing deepwater projects, with 270 large supply vessels 

using the port’s waterways each day (Greater Lafourche Port Commission, 2013). The OCS oil- and gasrelated demands upon coastal infrastructure and land use tend to be geographically concentrated as 

compared with historic residential settlement within the region. For instance, Port Fourchon is the service 

base for over 90 percent of OCS deepwater production and serves as a conduit for 15-18 percent of the 

Nation’s entire oil supply (Greater Lafourche Port Commission, 2011). As one of the most significant 

footprints within the OCS oil- and gas-related infrastructure corridor, Port Fourchon comprises only 

2.7 developed square miles (7 km2

) within a close to 44,000-mi2 (113,959-km2) state. In Louisiana, there 

are 105 persons per square mile, and in Lafourche Parish (where Port Fourchon is located), there are 

90 persons per square mile, both above the national average of 87 persons per square mile (USDOC, 

Census Bureau, 2010).
Description of the Environment and Impact Analysis 4-181

Navigation Canals

Chapter 3.1.2.1 of this Supplemental EIS, Chapter 3.1.2.1.8 of the 2012-2017 WPA/CPA Multisale 

EIS, and Chapter 3.1.2.1 of the WPA 233/CPA 231 Supplemental EIS discuss navigation channels along 

the Gulf Coast. Much of the traffic navigating these channels is unrelated to OCS activity, and the current 

system of navigation channels in the northern GOM is projected to be adequate for accommodating any 

additional traffic generated by a CPA proposed action. The Gulf-to-port channels and the Gulf 

Intracoastal Waterway that support prospective OCS ports are generally deep and wide enough to handle 

OCS oil- and gas-related traffic and are maintained by regular dredging if funding is available (Figure 3-7 

of the 2012-2017 WPA/CPA Multisale EIS). All single lease sales contribute to the demand for offshore 

supply/service vessel support; hence, they also contribute to the vessel traffic that moves in and out of 

support facilities. Therefore, a CPA proposed action is likely to contribute to the continued need for 

maintenance dredging of existing navigation channels. However, no new navigation channels are 

expected to be dredged as a result of a CPA proposed action because the existing system of navigation 

channels is projected to be adequate to allow proper accommodation for vessel traffic that will occur as a 

result of a CPA proposed action.

Transportation 

There is increasing demand to transport crude oil from Canadian and U.S. shale plays locations and 

send it by barge to Gulf Coast refineries. Scheduled to have opened in the second quarter of 2013 is the 

new Gulf Gateway Terminal, a crude oil destination terminal located at the Port of New Orleans. The 

terminal’s unloading capacity is designed to handle one unit train per day and to be equipped to transfer 

up to 10,000 bbl per hour directly into barges or into tanks with 103,000 bbl of usable storage (Gulf 

Gateway Terminal, 2013).

Louisiana Highway 1 (LA Hwy 1) is the only highway connecting Port Fourchon with the rest of 

Louisiana. This two-lane highway is surrounded by marshland and has been prone to extreme flooding 

over the years, jeopardizing critical access to Port Fourchon, which has up to 1,200 trucks travelling in 

and out of the port each day (Greater Lafourche Port Commission, 2013). Currently, LA Hwy 1 is closed 

an average of 3.5 days annually due to inundation. However, within 15 years, NOAA anticipates that the 

at-grade portions of LA Hwy 1 will be inundated by tides an average of 30 times annually, even in the 

absence of extreme weather. Because of Port Fourchon’s significance to the national, State, and local oil 

industry, the U.S. Department of Homeland Security, in July 2011, estimated that “a closure of 90 days 

could reduce national gross domestic product by $7.8 billion” (LA 1 Coalition, 2013). While, in the 

absence of planned expansions, LA Hwy 1 would not be able to handle future OCS and State activities, a 

multiphase LA Hwy 1 improvement project is currently underway. On July 8, 2009, the new LA Hwy 1 

fixed-span toll bridge over Bayou Lafourche connecting Port Fourchon and Leeville, Louisiana, was 

opened and marks partial completion of the first phase of improvements to LA Hwy 1 (Toll Roads News, 

2009). A large portion of the tolls collected will be paid by transportation activities associated with OCS 

oil- and gas-related activities. The remaining portion of Phase 1 construction, a two-lane elevated 

highway from the bridge to Port Fourchon, was completed in 2011. There are continuing efforts to get 

Federal funding to construct Phase 2 of the project—an elevated highway from the Golden Meadow 

floodgates to Leeville, Louisiana (Wilson, 2012).

The South Lafourche Leonard Miller Jr. Airport opened a partial parallel taxiway, and the Port 

Commission has plans to extend it to full length. In the past several years, $20 million has been invested 

in the airport for improvements that include the paving of airport roadways, runway expansion and 

overlay, installation of fuel tanks, and construction of an extra-large hangar. As a result of recent 

improvements, the airport is showing growth. Between 2012 and 2013, total aircraft operations at the 

South Lafourche Airport were the highest in airport history, exceeding 20,000 aircrafts (Greater 

Lafourche Port Commission, 2014).

If the service base expansion occurs in the cumulative case at the port of Galveston, Texas, or Mobile, 

Alabama, this expansion would occur in areas that are already industrialized and would have little effect 

on land use and infrastructure. This is also true for Port Fourchon, Louisiana, although, in the cumulative 

case, expansion of this service base may eventually be constrained by surrounding wetlands. Limited 

highway access and airport capacity could also constrain service base expansion at Port Fourchon in the 

cumulative case. However, ongoing and planned improvement projects make this unlikely.
4-182 Central Planning Area Lease Sales 235, 241, and 247 EIS

Waste Disposal Facilities

The OCS waste disposal is discussed above and in Chapter 3.1.2.2 of this Supplemental EIS, 

Chapters 4.2.1.23.1.1 and 3.1.2.2 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.23 of the 

WPA 233/CPA 231 Supplemental EIS. The scenario analysis concluded that no new solid-waste 

facilities would be built as a result of a single lease sale. Focused scenario analysis research into onshore 

waste disposal further supports the conclusion that existing solid-waste disposal infrastructure is adequate 

to support both existing and projected offshore oil and gas drilling and production needs (Dismukes et al., 

2007).

Oil Spills and Chemical/Drilling Fluid Spills 

Oil spills may be associated with exploration, production, or transportation activities that result from 

a CPA proposed action. A detailed risk analysis of offshore oil spills ranging from <1,000 bbl to ≥1,000 

bbl and coastal spills associated with a WPA proposed action is provided in Chapters 3.2.1.5, 3.2.1.6, 

and 3.2.1.7 of this Supplemental EIS and Chapters 3.2.1.5, 3.2.1.6, and 3.2.1.7 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS. 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 CPA proposed action are also presented in Table 3-12 of the 2012-2017 WPA/CPA 

Multisale EIS. Accidental spills as a result of a low-probability catastrophic event are discussed in 

Appendix B. 

Chemical and drilling-fluid spills may be associated with exploration, production, or transportation 

activities that result from a CPA proposed action. Chapter 3.2.5 of this Supplemental EIS and Chapter 

3.2.5 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS provide a 

detailed discussion of chemical and drilling-fluid spills. Each year, between 5 and 15 chemical spills are 

expected to occur; most of these are ≤50 bbl in size. Large spills are much less frequent. For example, 

from 1964 to 2005, only two chemical spills ≥1,000 bbl occurred. Even though additional production 

chemicals are needed in deepwater operations where hydrate formation is a possibility, spill volumes are 

expected to remain stable because of advances in subsea processing.

Non-OCS Oil- and Gas-Related Impacts

For a CPA proposed action, the primary region of geographic influence is coastal Texas, Louisiana, 

Mississippi, and Alabama. Land-use patterns vary greatly by region, reflecting differences in soils, 

climate, topography, and patterns of population settlement. Land-use changes will 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. The following sections are divided into those land use categories and other nonOCS oil- and gas-related, impact-producing factors including the following: (1) State oil and gas 

activities; (2) agriculture; (3) forest, parks, and special use areas; (4) urban areas; (5) miscellaneous areas; 

(6) inland navigable waterways and ports; and (7) natural processes.

State Oil and Gas Activities

Effects of State oil- and gas-related activities are expected to be similar to the effects from OCS oiland gas-related activities. 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. As described in Chapter 3.1.2.1 of this Supplemental EIS and Chapter 3.1.2.1 of the 

2012-2017 WPA/CPA Multisale EIS and the WPA 233/CPA 231 Supplemental EIS, 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. In 2011, Cheniere’s Sabine Pass facility in 

Louisiana received approval from DOE to export to any country in the world (Helman, 2013; USDOE, 

Federal Energy Regulatory Commission, 2013). Seventeen additional project sponsors have applied to 
Description of the Environment and Impact Analysis 4-183

DOE for authorization to export domestically produced LNG to free trade agreement and non-free trade 

agreement countries. BOEM will continue to monitor future development of new LNG export facilities, 

but these should not on their own represent a significant development or change in land use. 

Agriculture 

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 (State of Texas, Dept. of Agriculture, 2013). 

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 of close to 262,000 mi2 (679,095 km2

) for 

grassland pasture and range. Agriculture places many demands on 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.

Forest, Parks, and Special-Use Areas

Forest land, which the U.S. Forest Service defines as land at least 10 percent stocked by trees of any 

size, including land that formerly had such tree cover and that will be naturally or artificially regenerated, 

makes up 28 percent of the total land area in these four coastal states. Alabama has the most forest use 

land, with 70 percent of the State’s 53,868 mi2 (139,517 km2

) covered in forest, followed by Mississippi 

with 65 percent of its total land area covered in forest. From the Gulf Coast Flatwoods to the Upper 

Coastal Plains, forest resources abound in Mississippi. Forest resources represent the State’s largest 

single land use, covering more than 19.8 million ac (8.0 million ha) (Mississippi Forestry Commission, 

2009). Rural lands, including privately owned forest, total 144 million ac (58 million ha), 86 percent of 

the Texas’s total land area (State of Texas, Dept. of Agriculture, 2013). Forest use land includes 

timberland and reserved forest land, but it excludes forest land in parks, wildlife areas, and similar special 

purpose uses. Special-use areas (which include areas in highway, road, and railroad rights-of-way and 

airports; Federal and State parks, wilderness areas, and wildlife refuges; and national defense and 

industrial areas) make up 4 percent of the total land area for these four coastal states. Louisiana has the 

highest percentage of special-use area, with 7 percent of the land used for special-use purposes 

(Lubowski, et al., 2006). Texas, for instance, has 2 national parks and well over 100 State parks, national 

parks, and historic sites. Texas has 15 military bases throughout the state, Louisiana has 4 military bases, 

and Mississippi and Alabama each have 5 military bases (MilitaryBases.com, 2013a and b). The U.S. 

Congress decides when and where a military base will be established, but regardless of the branch of 

military, the new site and its associated environmental impacts would be subject to NEPA. 

Texas has more than 10,000 mi (16,093 km) of railroad tracks, more than any other state. Those 

tracks are owned or operated by Union Pacific Railroad (6,408 mi; 10,313 km), the Burlington 

Northern/Santa Fe Railway (4,645 mi; 7,475 km), and the Kansas City Southern Railway (379 mi; 

610 km). Also, the Texas State highway system consists of about 79,696 centerline miles (miles traveled 

in a one-way direction regardless of the number of lanes) of road and carries about 74 percent of the 

State’s vehicular traffic. Included are 28,374 mi (45,664 km) of U.S. and State highways, carrying 

36 percent of traffic (including 22 centerline miles of toll roads); 40,988 mi (65,967 km) of farm-tomarket roads, carrying 11 percent of traffic; 9,953 mi (16,018 km) of interstate highways and frontage 

roads, carrying 26 percent of traffic; and 339 mi (546 km) of parks and recreation roads, carrying less 

than 1 percent of traffic. An additional 65 centerline miles of toll roads are under construction (State of 

Texas, Comptroller of Public Accounts, 2013).

Louisiana’s highway network is the 32nd largest in the Nation, with the State highway system the 11th

largest. The network is comprised of over 60,000 mi (96,561 km) and more than 13,000 bridges under 

the jurisdiction of Federal, State, and local governments and entities. The 27.4 percent of highway 

network centerline mileage that are State-owned places Louisiana 10th nationally, while the 30 percent of 
4-184 Central Planning Area Lease Sales 235, 241, and 247 EIS

total highway network lane mileage that are State-owned places Louisiana 11th (State of Louisiana, Dept. 

of Transportation and Development, 2013). The network typically handles just under 41 billion mi 

(66 billion km) traveled annually. Louisiana also has 2,656 mi (4,274 km) of Class I railroad trackage 

and 2,823 mi (4,543 km) of inland waterways (State of Louisiana, Dept. of Transportation and 

Development, 2013). Five interstate highways converge in Alabama, allowing goods to be shipped to 

major markets. The I-22 is planned to be completed by 2014, making this the sixth interstate in Alabama 

(Economic Development Partnership of Alabama, 2013). The impacts of transportation corridors include 

noise, air pollution, and potential loss of living quality. Wildlife and plants suffer from habitat 

destruction and various forms of pollution. Ecosystems suffer fragmentation with habitats, and biomes 

that had worked in cohesion are separated. Transportation projects may also necessitate the draining or 

contamination of wetlands, crucial habitat for many species and important for flood control and filtering 

and cleaning water (USEPA, 1994). As a large-scale infrastructure project with potential environmental 

impacts, any new highway or rail corridor would be subject to Federal NEPA requirements as well as 

local and State regulatory scrutiny.

Urban Areas 

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. The total urban land area for all four states 

is just 3 percent of the total land area, with Louisiana and Alabama tied for the highest percentage of 

urban areas, with 4 percent of each state being utilized for high population 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 effects 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 will be largely 

determined by economics, demographic shifts, local ordinances, and zoning (USEPA, 2013c).

Miscellaneous Areas

The final land use category according to the Economic Research Service, “Miscellaneous,” includes 

industrial and commercial sites in rural areas, cemeteries, golf courses, mining areas, quarry sites, 

marshes, swamps, sand dunes, bare rocks, deserts, tundra, rural residential, and other unclassified land. 

For Alabama, Mississippi, and Texas, 4 percent of land use is classified as miscellaneous; however, in 

Louisiana, 16 percent of land use is classified as miscellaneous. Louisiana contains 40-45 percent of the 

wetlands found in the lower states within its 195,000-mi2 (505,048-km2

) footprint (USDOI, GS, 2012b). 

Inland Navigable Waterways and Ports

Coastal states with inland navigable waterways and direct access to the Gulf of Mexico are uniquely 

positioned to benefit from international trade and facilitate domestic trade. The Ports of South Louisiana 

and Houston rank 12th and 13th, respectively, in total trade for all world ports and 1st and 2nd, respectively, 

for American ports (American Association of Port Authorities, 2011). With direct access to the 

Mississippi River and its system of inland rivers, the Port of South Louisiana averages 223 million metric 

tons per year. In Louisiana, there are 2,823 mi (4,543 km) of inland waterways (State of Louisiana, Dept. 

of Transportation and Development, 2013). Alabama’s water corridors connect to over 15,000 mi 

(24,140 km) of inland waterways in 23 states (Economic Development Partnership of Alabama, 2013). 

The Gulf Intracoastal Waterway runs 1,050 mi (1,690 km), connecting Gulf ports from Carrabelle, 

Florida, to Brownsville, Texas. In Texas alone, the waterway extends 423 mi (681 km). The Port of 

Houston handled 215 million metric tons in total cargo in 2011 (American Association of Port 

Authorities, 2011). The primary issue facing ports and inland navigable waterways is availability of 

funds and dredge vessels to maintain navigable depths and widths. The Harbor Maintenance Tax, 

established in 1986, is an ad valorem tax paid on the value of imports entering the U.S. on domestic 
Description of the Environment and Impact Analysis 4-185

cargo. Appropriations for the Harbor Maintenance Tax Fund, which are primarily used by COE for 

maintenance dredging, dredged material disposal areas, jetties and breakwaters, have lagged behind 

revenues (Ojard, 2013). While industry continues to plan for improvements and set aside funding, 

Congress has not appropriated funds to meet the demand for repairs and improvements, which have 

resulted in channels not being maintained to their constructed depths and widths. The America Society of 

Civil Engineers rated inland waterways with a D+ (poor) and gave ports a C (mediocre) in its 2013 report 

card (American Society of Civil Engineers, 2013). The Big River Coalition completed a study in 2013, 

which looked at the economic impact of dredging the Mississippi River to deeper depths. It found that for 

every 1,000 tons of cargo gained due to the deepening, the local economy will gain $14,691 in spending 

on ship services (e.g., loading, unloading, freight forwarding, dockage, etc.); inland transportation; and 

increased business for port users, mostly manufacturing firms. This gain in direct spending creates 

additional impacts in the local economy in secondary spending, sometimes referred to as the “ripple 

effect,” total spending (direct plus secondary spending), earnings of affected workers, jobs, and tax 

revenues for local, State, and Federal governments (Big River Coalition, 2013).

The U.S. Energy Sector has long prepared for all hazards, but natural disasters have traditionally been 

a key focus of sector efforts. The National Infrastructure Protection Plan, a comprehensive risk 

management framework that defines critical infrastructure protection roles and responsibilities for all 

levels of government, private industry, and other sector partners has evolved to identify and prepare other 

hazards that include terrorism (domestic and international), cyber security, and pandemics (USDHS, 

2010). The Energy Sector-Specific Plan: An Annex to the National Infrastructure Protection Plan details 

how the National Infrastructure Protection Plan risk management framework is implemented within the 

context of the unique characteristics and risk landscape of the sector (USDHS, 2010). Each SectorSpecific Agency develops a sector-specific plan through a coordinated effort involving its public and 

private sector partners. The DOE is designated as the Sector-Specific Agency for the Energy Sector. The 

energy infrastructure provides essential fuel to all of the other critical infrastructures, and in turn depends 

on the Nation’s transportation, information technology, communications, finance, and government 

infrastructures. Over time, cyber/information technology dependencies have increased. For example, 

electricity and natural gas suppliers rely heavily on data collection systems to ensure accurate billing. 

Energy control systems and the information and communications technologies on which they rely play a 

key role in the North American energy infrastructure. Energy infrastructure resilience is defined as the 

ability to reduce the magnitude and/or duration of disruptive events. The resilience of an infrastructure or 

enterprise depends on its ability to anticipate, absorb, adapt to, and/or rapidly recover from a disruptive 

event. The DOE, in cooperation with other Federal agencies, State and local governments, and sector 

partners, has undertaken programs to assess the risks of key energy infrastructure assets and to provide 

technology, tools, and expertise to Federal, State, local, Tribal, and territorial entities, and to public and 

private owners and operators of critical infrastructure. These programs are designed to assist all entities 

within the energy infrastructure in securing systems against physical and cyber attacks.

Natural Processes

A U.S. Geological Survey study published in spring 2013, Economic Vulnerability to Sea-Level Rise 

along the Northern U.S. Gulf Coast (Thatcher et al., 2013), applied a Coastal Economic Vulnerability 

Index (CEVI) to the northern Gulf coastal region in order to measure economic vulnerability to sea-level 

rise. Coastal landloss in Louisiana is an ongoing threat to the people and industry of that region—

Louisiana has the greatest rate of landloss in the Nation. Louisiana contains 40-45 percent of the 

wetlands found in the lower states within its 195,000-mi2 (505,048-km2

) footprint (USDOI, GS, 2012b). 

Louisiana also has the greatest rate of landloss in the Nation. The U.S. Geological Survey projects that 

coastal Louisiana has undergone a net change in land area of about 1,883 mi2 (4,897 km2

) from 1932 to 

2010. 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 Gulf 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 (Thatcher, et al, 2013). 

For a more detailed discussion of this study and how it relates to environmental justice communities, refer 

to Chapter 4.1.1.23.4 of this Supplemental EIS, Chapter 4.2.1.23.4 of the 2012-2017 WPA/CPA 

Multisale EIS, and Chapter 4.2.1.23.4 of the WPA 233/CPA 231 Supplemental EIS. A Louisiana State-
4-186 Central Planning Area Lease Sales 235, 241, and 247 EIS

sponsored study found that the “gradual erosion of Louisiana’s coast may force the oil and gas industry to 

interrupt, postpone, or permanently delay the production and transportation of oil and gas products” 

(Richardson and Scott, 2004). It is unknown how current subsidence and erosion is impacting industry or 

whether industry is making plans to mitigate current or future impacts. BOEM will continue to monitor 

industry and its infrastructure footprint over time to document short- and long-term impacts of continued 

landloss. For a more detailed discussion on deltaic landloss, refer to Chapter 4.1.1.4 of this 

Supplemental EIS, Chapter 4.2.1.4 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.4 of the 

WPA 233/CPA 231 Supplemental EIS. 

While coastal infrastructure is subject to the impacts of coastal landloss and routine tropical storm 

activity, there is still considerable investment to expand and improve existing infrastructure. In June 

2013, Governor Bobby Jindal of Louisiana signed Senate Bill 122, which modified the Investor Tax 

Credit and the Import-Export Tax Credit. The new credits now include projects like warehousing and 

storage, port operations, marine cargo handling, ship building and repairs, and oil and gas activities (State 

of Louisiana, Office of Governor, 2013). Additionally, the decision criteria for the State of Louisiana’s 

5-year coastal restoration planning document places a higher value on collections of risk reduction and 

restoration projects that improve coastal conditions for oil and gas infrastructure and increase the 

resilience of coastal communities that support the industry. The criterion also puts a higher value on 

projects that benefit the navigation industry and places a lower value on projects that impede navigation 

(State of Louisiana, Coastal Protection and Restoration Authority, 2012). Meanwhile, Texas experiences 

an overall loss of almost 6,000 ac (2,428 ha) of tidal and nontidal wetlands per year (State of Texas, 

General Lands Office, 2010). The Texas Coastal Erosion Planning and Response Act Program, which is 

administered by the Texas General Land Office, oversees restoration projects throughout the state. 

Restoration plans also focus on mitigating the impacts of tropical storms and land subsidence. Landsurface subsidence, or land subsidence, in areas including Harris County, Texas, which encompasses 

much of the Houston area, has been occurring for decades. Land subsidence has increased the frequency 

and extent of flooding, damaged buildings, and transportation infrastructure (Kasmarek et al., 2009). In 

addition to public efforts, private industry has teamed up with nongovernment organizations like the 

Nature Conservancy to mitigate risks from storms and flooding through small-scale restoration projects 

near private infrastructure. For instance, the Dow Chemical Company Collaboration partnered with The 

Nature Conservancy to evaluate green infrastructure solutions (e.g., protecting or restoring marshes, 

oyster reefs, etc.) alongside gray infrastructure solutions in their coastal hazard mitigation planning for 

their Freeport, Texas, facilities (Dow Chemical Company Collaboration, 2011).

Summary and Conclusion 

Activities relating to the OCS Program and State oil and gas production are expected to minimally 

affect the current land use of the analysis area because most subareas have strong industrial bases and 

designated industrial parks to accommodate future growth in oil and gas businesses. BOEM projects 

0-1 new gas processing facilities and 0-1 new pipeline landfalls for a CPA proposed action, although this 

is a conservative estimate and the number is much closer to zero than to one. If a new gas processing 

facility or pipeline landfall were to occur, it would likely be toward the end of the 40-year analysis period 

(Dismukes, official communication 2011b). There may be a new increased demand for waste disposal

services as a result of a CPA proposed action. Any service base expansion in the cumulative case would 

be limited, would occur on lands designated for such purposes, and would have minimal effects on land 

use and infrastructure. However, in the cumulative case, it is possible that Port Fourchon expansions may 

eventually be constrained by surrounding wetlands. Based on the available information and current 

BOEM scenario projections, the cumulative impacts on land use and coastal infrastructure from OCS oiland gas-related activities are expected to be minor. Therefore, the incremental contribution of a CPA 

proposed action to the cumulative impacts on land use and coastal infrastructure is also expected to be 

minor.

The coastal infrastructure supporting a CPA proposed action represents only a small portion of the 

coastal land and infrastructure throughout the CPA and Gulf of Mexico, and little change is expected to 

occur due to changing agricultural and extractive (e.g., lumbering and petroleum) uses of onshore land. 

Many non-OCS oil- and gas-related factors contribute substantially to the cumulative impacts to land use

and coastal infrastructure, including housing and other residential developments; the development of 

private and publicly owned recreational facilities; the construction and maintenance of industrial facilities 
Description of the Environment and Impact Analysis 4-187

and transportation systems; urbanization; city planning and zoning; changes to public facilities such as 

water, sewer, educational, and health facilities; changes to military bases and reserves; changes in 

population density; changes in State and Federal land-use regulations; and changes in non-OCS oil- and 

gas-related demands for water transportation systems and ports. Given the overwhelming contribution of 

these non-OCS oil- and gas-related factors to the cumulative impacts on land use and coastal 

infrastructure and the small incremental contribution of a CPA proposed action, the cumulative impacts 

on land use and coastal infrastructure are also expected to be minor.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

Additional research was conducted to investigate the availability of recent information affecting land 

use and coastal infrastructure since publication of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. Various Internet sources were examined, including the websites of 

numerous Federal and State agencies (USDHS, Federal Emergency Management Agency; USDOC, 

Bureau of the Census; USDOC, NOAA; USDOE, Energy Information Administration; USDOT, 

Maritime Administration; USDOI, FWS; RestoreTheGulf.gov website; Deepwater Horizon Oil Spill

Portal; USEPA; Louisiana Department of Environmental Quality; Louisiana Recovery Authority; 

Louisiana Office of Community Development; Mississippi Department of Environmental Quality; 

Alabama Department of Environmental Management; and the Florida Department of Environmental 

Protection). Further information was sought from other organizations, recently published journal articles, 

and trade publications such as The Greater Lafourche Port Commission, LA1 Coalition, The Oil Drum, 

Rigzone, Oil and Gas Journal, Offshore Magazine, TOLLROADS News, and The Energy Journal. This 

research revealed Sasol, Inc.’s plan to build a gas-to-liquids processing facility in Calcasieu Parish, 

Louisiana. This would be the first gas-to-liquids facility constructed in the United States. Plans call for 

an 18-month feasibility study to consider two development options, specifically, whether it will produce 

2 million tons per year or 4 million tons per year (Troy, 2011). At present, BOEM believes that most of 

this gas will be sourced from onshore unconventional reserves rather than from OCS supplies. BOEM 

will continue to monitor future development of this new coastal infrastructure category (gas-to-liquids 

facilities), but this one proposed plan would not be expected to on its own represent a significant 

development or change in land use.

BOEM will continue to monitor these infrastructure effects as they evolve over time. Although this 

information on infrastructure effects is evolving and may be relevant to reasonably foreseeable significant 

impacts to the Gulf economy, this information would not be essential to a reasoned choice among the 

alternatives because regardless of whether the decisionmaker chooses to hold a proposed lease sale under 

the Action alternatives or chooses the No Action alternative, there remain many preexisting OCS leases in 

the CPA that would continue to support the economy. A CPA proposed action would not be expected to, 

on its own, result in significant impacts. The incomplete or unavailable information, even if available, 

would not be expected to change these conclusions.

A U.S. Geological Survey study published in spring 2013, Economic Vulnerability to Sea-Level Rise 

along the Northern U.S. Gulf Coast (Thatcher et al., 2013), applied a CEVI to the northern Gulf coastal 

region in order to measure economic vulnerability to sea-level rise. Coastal landloss in Louisiana is an 

ongoing threat to the people and industry of that region. Louisiana has the greatest rate of landloss in the 

Nation. The U.S. Geological Survey projects that coastal Louisiana has undergone a net loss in land area 

of about 1,883 mi2 (4,897 km2

) from 1932 to 2010. 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 

Gulf 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 (Thatcher et al, 2013). For a more detailed discussion of this study and how it 

relates to environmental justice communities, refer to Chapter 4.1.1.23.4 of this Supplemental EIS, 

Chapter 4.2.1.23.4 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.23.4 of the WPA 

233/CPA 231 Supplemental EIS.

While coastal infrastructure is subject to the impacts of coastal landloss and routine tropical storm 

activity, there is still considerable investment to expand and improve existing infrastructure. In June 

2013, Governor Bobby Jindal of Louisiana signed Senate Bill 122, which modified the Investor Tax 
4-188 Central Planning Area Lease Sales 235, 241, and 247 EIS

Credit and the Import-Export Tax Credit. The new credits now include projects like warehousing and 

storage, port operations, marine cargo handling, ship building and repairs, and oil and gas activities (State 

of Louisiana, Office of Governor, 2013). Additionally, the decision criteria for the State of Louisiana’s 

5-year coastal restoration planning document places a higher value on collections of risk reduction and 

restoration projects that improve coastal conditions for oil and gas infrastructure and increase the 

resilience of coastal communities that support the industry. The criteria also put a higher value on 

projects that benefit the navigation industry and places a lower value on projects that impede navigation 

(State of Louisiana, CPRA, 2012). In addition to public efforts, private industry has teamed up with 

nongovernment organizations like The Nature Conservancy to mitigate risks from storms and flooding

through small-scale restoration projects near private infrastructure. For instance, the Dow Chemical 

Company Collaboration partnered with The Nature Conservancy to evaluate green infrastructure solutions 

(e.g., protecting or restoring marshes, oyster reefs, etc.) alongside gray infrastructure solutions in their 

coastal hazard mitigation planning for their Freeport, Texas, facilities (Dow Chemical Company 

Collaboration, 2011).

The Gulf of Mexico OCS exploration and production industry has more or less recovered from the 

effects of the Deepwater Horizon explosion, oil spill, and response, including the related drilling 

suspensions and the development of needed adaptations to new Federal requirements for drilling safety. 

In 2012, Federal regulators issued the most permits for deepwater drilling in the Gulf of Mexico since 

2007, with BSEE approving 520 deepwater well permit applications in 2012 alone (Dupre, 2013; USDOI, 

BSEE, 2013b). If drilling activity continues with its current upward trajectory, there may be new 

increased demand for waste disposal services as a result of a CPA proposed action. Current capacity, 

however, should be able to accommodate any increased demand. The Argonne National Laboratory 

reported that there were 46 waste management facilities that serviced the oil and gas industry along the 

GOM, with 18 in Louisiana and 18 in Texas, as well as numerous salt caverns used for oil and gas waste 

disposal scattered throughout Texas (Dismukes, official communication, 2013b). There are also facilities 

equipped to recycle some of the wastes associated with exploration and production, and industry and 

universities are also working on technologies to utilize exploration and production wastes, such as drill 

cuttings, as inputs for construction materials (Saunders, 2012).

As described in Chapter 3.1.2.1 of this Supplemental EIS and Chapter 3.1.2.1 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, 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. In 2011, Cheniere’s Sabine Pass, Louisiana, facility received approval from 

DOE to export to any country in the world (Helman, 2013; USDOE, Federal Energy Regulatory 

Commission, 2013). Seventeen additional project sponsors have applied to DOE for authorization to 

export domestically produced LNG to free trade agreement and non-free trade agreement countries. 

BOEM will continue to monitor future development of new LNG export facilities, but these should not on 

their own represent a significant development or change in land use. 

4.1.1.23.2. Demographics

BOEM has reexamined the analysis for demographics presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

demographics presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

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

CPA proposed action are presented in Chapter 4.2.1.23.2 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.23.2 of the WPA 233/CPA 231 Supplemental EIS. A 

CPA proposed action’s incremental contribution to the cumulative impacts is presented below. Any new 

information that has become available since the publication of these documents is presented below. A 

detailed description of demographics can be found in Chapter 4.2.1.23.2.1 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.23.2 of the WPA 233/CPA 231 

Supplemental EIS.
Description of the Environment and Impact Analysis 4-189

Impacts of Routine and Accidental Events

A detailed impact analysis of the routine impacts of proposed CPA Lease Sales 235, 241, and 247 on 

demographics can be found in Chapter 4.2.1.23.2.2 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.23.2 of the WPA 233/CPA 231 Supplemental EIS.

In general, impact producing factors that cause employment impacts, such as exploration and 

delineation activities, development and production activities, and coastal infrastructure development, can 

have some impacts on the demographic characteristics of a particular area. However, routine activities 

associated with a CPA proposed action are projected to minimally affect the demography of the analysis 

area. The projected impacts to population arising from a lease sale are calculated by multiplying the 

employment estimates from the mathematical model MAG-PLAN by an estimate of the number of 

members in a typical family. The projected population increases arising from a lease sale are then divided 

by the population forecasts in Woods and Poole, Inc. (2013), which yields the percentage impacts to 

population of a lease sale. Population impacts from a CPA proposed action are projected to be minimal 

(<1% of the total population) for all Economic Impact Areas (EIA’s) in the Gulf of Mexico region.

A detailed analysis of the accidental impacts that may be associated with proposed CPA Lease Sales 

235, 241, and 247 on demographics can be found in Chapter 4.2.1.23.2.3 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.23.2 of the WPA 233/CPA 231 

Supplemental EIS.

Accidental events associated with a CPA proposed action, such as low to moderate scale oil or 

chemical spills, blowouts, and vessel collisions, would likely have no effects on the long-term 

demographic characteristics of the Gulf coastal communities. This is because accidental events typically 

cause only short-term population movements as individuals seek employment related to the event or have 

their existing employment displaced during the event. For a detailed discussion on the employment and 

demographic impacts of a low-probability catastrophic spill, refer to Appendix B. 

Summary and Conclusion

BOEM has reexamined the analysis for demographics presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for 

demographics presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS because the new Woods and Poole data did not change much from what was presented 

in those documents. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

Cumulative Impacts

Background/Introduction 

This section considers the combined effects of OCS oil- and gas-related and non-OCS oil- and gasrelated factors on demographics in the Gulf of Mexico. The demographic characteristics of any area 

include the distribution of population, age, gender, ethnicity, employment, and earnings in that area. The 

OCS oil- and gas-related factors that could impact the demographics of any area consist of routine 

activities and accidental events arising from prior, current, and future OCS lease sales. The impacts of 

routine activities and accidental events on demographics are discussed above; the impacts of a lowprobability catastrophic oil spill are discussed in Appendix B. There are numerous non-OCS oil- and 

gas-related factors that could impact demographics, including fluctuations in workforce, net migration, 

relative income, oil and gas activity in State waters, and offshore liquefied natural gas activity. Most 

approaches to analyzing cumulative effects begin by assembling a list of projects and actions that will 

likely be associated with a CPA proposed action. However, no such list of future projects and actions 

could be assembled that would be sufficiently current and comprehensive to support a cumulative analysis 

for all 132 of the coastal counties and parishes in the analysis area over a 40-year period. Instead, this 

analysis uses the economic and demographic projections from Woods & Poole Economics, Inc. (2013) as 

a reasonable approximation to define the contributions of other likely projects, actions, and trends to the 

cumulative case. These projections include population associated with the continuation of current 
4-190 Central Planning Area Lease Sales 235, 241, and 247 EIS

patterns of OCS leasing activity as well as the continuation of trends in other industries important to the 

region.

OCS Oil- and Gas-Related Impacts 

The projected impacts to population arising from the OCS Program are calculated by multiplying the 

employment estimates from the mathematical model MAG-PLAN by an estimate of the number of 

members in a typical family. The projected population increases arising from the OCS Program are then 

divided by the population forecasts in Woods and Poole, Inc. (2013), which yields the percentage impacts 

of the OCS Program. For more information about MAG-PLAN, refer to Chapter 4.1.1.23.3 of this 

Supplemental EIS and Chapter 4.2.1.23.3.2 of the 2012-2017 WPA/CPA Multisale EIS. Table 4-7

presents estimates of the population impacts of the OCS Program under the low-case and high-case 

exploration and development scenarios. These cumulative scenarios reflect activities that are expected to 

arise from prior, current, and future OCS lease sales. The cumulative projections reflect the positive 

contribution to population that will arise from increased employment arising from OCS oil and gas 

activities, as well as the positive impacts to population that will arise from maintaining current 

employment in OCS oil- and gas-related industries. The OCS Program is projected to have the greatest 

positive impacts on population in the following EIA’s (the low-case and high-case percentage impacts are 

in parenthesis, respectively): LA-2 (3.3%, 5.1%); LA-3 (2.5%, 3.9%); LA-1 (2.2%, 3.6%); MS-1 (1.6%, 

2.6%); TX-3 (1.5%, 2.2%); and AL-1 (1.3%, 2.2%). A CPA proposed action would represent a small 

fraction of these broader impacts.

A CPA proposed action would also incrementally contribute to the risk of oil spills that could arise 

from the OCS Program. However, oil spills typically cause only short-term population movements as 

individuals seek employment related to the event or have their existing employment displaced during the 

event.

Non-OCS Oil- and Gas-Related Impacts

Table 4-8 provides projections of the evolution of the total population in all EIA’s in future years. 

These projections incorporate the impacts from all non-OCS oil- and gas-related sources, such as 

fluctuations in workforce, net migration, relative income, oil and gas activity in State waters, and offshore 

liquefied natural gas activity. In 2012, the total Gulf Coast population was 25.19 million. In 2012, the 

EIA’s with the largest populations were TX-3 (6.44 million), FL-4 (6.36 million), and FL-3 

(3.72 million). The EIA’s with the smallest populations were LA-1 (349,640), MS-1 (489,210), and LA-2 

(598,630). For all EIA’s combined, it is expected that the total population will grow at a 1.3 percent rate 

between 2012 and 2051. The fastest population growth is expected in TX-3 (1.6%), LA-2 (1.4%), and 

TX-1 (1.4%); the slowest population growth is expected in LA-4 (0.5%) and MS-1 (0.6%). Tables 4-9 

through 4-21 provide projections of employment, income, wealth, business patterns, and racial 

composition for individual EIA’s.

The racial and ethnic composition of the analysis area is influenced by many non-OCS oil- and gasrelated sources, including settlement patterns and employment opportunities in various economic sectors. 

For example, those areas in Texas where Hispanics are the dominant group (i.e., EIA TX-1 where they 

represent 82% of the population) were also first settled by people from Mexico. By TX-3, the size of the 

African-American population increases, and there is a more diversified racial mix. In Louisiana, 

Mississippi, Alabama, and northern Florida (FL-1 and FL-2), African Americans outnumber Hispanics. 

A more detailed discussion of minority populations in the area can be found in Chapter 4.1.1.23.4. As 

discussed above, the impacts of a CPA proposed action to these projected demographic trends are 

expected to be minimal.

Summary and Conclusion

A CPA proposed action is projected to have an incremental contribution of less than 1 percent to the 

population level in any of the EIA’s, in comparison to other factors influencing population growth, such 

as the status of the overall economy, fluctuations in workforce, net migration, and changes in income. 

Given both the low levels of population growth and industrial expansion associated with a CPA proposed 

action, it is expected that the baseline age and racial distribution pattern will continue through the analysis 

period.
Description of the Environment and Impact Analysis 4-191

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

BOEM conducted a search of known data sources related to demographics and Internet resources. 

The primary source of new information is Woods & Poole Economics, Inc. (2013), which is an annual 

update of the data that were used in the WPA 233/CPA 231 Supplemental EIS. Woods & Poole 

Economics, Inc. (2013) provides projections of economic and demographic variables at the county level. 

Table 4-8 provides projections of the evolution of the total population in all EIA’s in future years. These 

projections assume the continuation of existing social, economic, and technological trends at the time of 

the forecast. In 2012, the total Gulf Coast population was 25.19 million. In 2012, the EIA’s with the 

largest populations were TX-3 (6.44 million), FL-4 (6.36 million), and FL-3 (3.72 million). The EIA’s 

with the smallest populations were LA-1 (349,640), MS-1 (489,210), and LA-2 (598,630). For all EIA’s 

combined, it is expected that the total population will grow at a 1.3 percent rate through 2051. The fastest 

population growth is expected in TX-3 (1.6%), LA-2 (1.4%), and TX-1 (1.4%); the slowest population 

growth is expected in LA-4 (0.5%) and MS-1 (0.6%). Tables 4-9 through 4-21 provide projections of 

employment, income, wealth, business patterns, and racial composition for individual EIA’s. In general, 

the projections of these variables have not changed noticeably from the projections in the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

4.1.1.23.3. Economic Factors

BOEM has reexamined the analysis for economic factors presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

economic factors presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

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

CPA proposed action are presented in Chapters 4.2.1.23.3.2 and 4.2.1.23.3.3 of the 2012-2017 WPA/CPA 

Multisale EIS and Chapter 4.2.1.23.3 of the WPA 233/CPA 231 Supplemental EIS. A CPA proposed 

action’s incremental contribution to the cumulative impacts is presented below. Any new information 

that has become available since those documents were published is presented below.

A detailed description of economic factors can be found in Chapter 4.2.1.23.3.1 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.23.3 of the WPA 

233/CPA 231 Supplemental EIS.

Impacts of Routine and Accidental Events

A detailed impact analysis of the routine impacts of proposed CPA Lease Sales 235, 241, and 247 on 

economic factors can be found in Chapter 4.2.1.23.3.2 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.2.1.23.3 of the WPA 233/CPA 231 Supplemental EIS.

As a result of proposed CPA Lease Sales 235, 241, and 247, there would be only minor economic 

changes in the Texas, Louisiana, Mississippi, Alabama, and Florida EIS’s. This is because the demand 

would be met primarily with the existing population and labor force. Most of the employment related to 

proposed CPA Lease Sales 235, 241, and 247 is expected to occur in Texas (primarily in the EIA TX-3) 

and in the coastal areas of Louisiana. A CPA proposed action, irrespective of whether one analyzes the 

high-case or low-case production scenario, would not cause employment effects >1 percent in any EIA 

along the Gulf Coast.

A detailed impact analysis of the accidental impacts that may be associated with proposed CPA Lease 

Sales 235, 241, and 247 on economic factors can be found in Chapter 4.2.1.23.3.3 of the 2012-2017 

WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.23.3 of the WPA 

233/CPA 231 Supplemental EIS.

An oil spill can cause a number of disruptions to local economies. Many of these effects are due to 

industries that depend on damaged resources. However, the impacts of an oil spill can be somewhat 

broader if companies further along industry supply chains are affected. These effects depend on issues 
4-192 Central Planning Area Lease Sales 235, 241, and 247 EIS

such as the duration, methods, and logistics of the cleanup operations and the responses of policymakers 

to a spill. However, the impacts of small-to medium-sized spills should be localized and temporary.

Summary and Conclusion

BOEM has reexamined the analysis for economic factors presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. No new significant information was discovered that would alter the impact conclusion for 

economic factors presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS because the new information was roughly in line with prior expectations. The analysis 

and potential impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 

233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction 

The cumulative impacts on economic factors will arise from the expected progression of the broader 

OCS Program, the expected progression of overall economic activity, the potential risks of oil spills, and 

the potential risks of natural events such as hurricanes. 

OCS Oil- and Gas-Related Impacts 

A CPA proposed action would contribute to the economic effects of the broader OCS Program. The 

OCS Program directly affects firms that are responsible for well drilling, equipment manufacturing, 

pipeline construction, and servicing OCS activities. The OCS oil- and gas-related activities also impact 

the suppliers to those firms, as well as firms that depend on consumer spending of oil and gas industry 

workers. These activities support employment (and the corresponding levels of population) in various 

areas in the Gulf of Mexico region. In order to estimate the scale of these effects, BOEM has developed 

the mathematical model MAG-PLAN, which is a two-stage 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; these scenarios include estimates of activities such as drilling, platform installations, and 

structure removals. These estimates arise from a detailed analysis of the numerous activities that are 

needed to directly support OCS oil- and gas-related operations. The second stage estimates the impacts of 

oil and gas industry spending on the broader economies along the Gulf Coast. First, direct OCS oil- and 

gas-related industry spending will support activities further down the supply chain; these are referred to as 

“indirect” economic impacts. In addition, the incomes of employees along the OCS industry’s supply 

chain will support consumer spending throughout the economy; these are referred to as “induced” 

economic impacts. These indirect and induced effects are estimated using the widely used economic 

modeling software IMPLAN. In particular, MAG-PLAN uses IMPLAN “multipliers” to compute how 

direct OCS spending circulates within the economy and translates into additional indirect and induced 

economic impacts. The MAG-PLAN has some limitations. For example, its employment estimates are 

not able to fully take into account the expected progression of the economy in future years. However, 

MAG-PLAN still provides reasonable estimates of the relative scale of the economic impacts of OCS 

activities. The initial version of MAG-PLAN is outlined in Manik et al. (2005). BOEM has made a 

number of adjustments to MAG-PLAN in recent years. For example, BOEM has incorporated the use of 

a number of new technologies, such as subsea systems and floating production, storage, and offloading 

system units, into MAG-PLAN. BOEM has also incorporated additional data regarding onshore support 

activities into the model. More information regarding the most recent version of MAG-PLAN can be 

found in Eastern Research Group, Inc. (2012). 

Table 4-22 presents data on the peak levels of employment in EIA’s that are forecasted to arise from 

the entire Gulf of Mexico OCS Program. The peak employment levels for the entire OCS industry are 

primarily felt in Louisiana and Texas (primarily in the EIA TX-3). The OCS activities will support 

53,000 jobs in TX-3 in the peak employment year according to the low-production scenario and over 

78,000 jobs in the high-production scenario. However, as can be seen in Table 4-22, the OCS industry 

will make up a larger fraction of the economy of south Louisiana. For example, in LA-2, under the highcase scenario, the OCS industry will support 3.5 percent of total employment, while in TX-3, the OCS 
Description of the Environment and Impact Analysis 4-193

industry will support 1.5 percent of total employment. Employment demand will continue to be met 

primarily with the existing population and available labor force in most EIA’s. The vast majority of these 

cumulative employment estimates represent existing jobs from previous OCS Program actions. BOEM 

does expect some employment will be met through in-migration; however, this level is projected to be 

small and localized. As discussed in Chapter 4.1.1.23.3, a CPA proposed action is expected to 

contribute less than 1 percent to the employment level in each of the EIA’s.

Oil Spills

A CPA proposed action would contribute to the risk of an oil spill arising from the broader OCS 

Program. The impacts of low to moderate oil spills are discussed in Chapter 4.2.1.23.3.3 of the 2012-

2017 WPA/CPA Multisale EIS and Chapter 4.2.1.23.3 of the WPA 233/CPA 231 Supplemental EIS. The 

impacts of a low-probability catastrophic oil spill are discussed in Appendix B. In general, a CPA 

proposed action would only slightly increase the likelihood of oil spills.

Non-OCS Oil- and Gas-Related Impacts

Most approaches to analyzing cumulative effects begin by assembling a list of other likely projects 

and actions that would be included with a CPA proposed action for analysis. However, no such list of 

future projects and actions could be assembled that would be sufficiently current and comprehensive to 

support a cumulative analysis for all 132 of the coastal counties and parishes in the analysis area over a 

40-year period. Instead of an arbitrary assemblage of future possible projects and actions, this analysis 

employs the economic and demographic projections from Woods & Poole Economics, Inc. (2013) to 

define the contributions of other likely projects, actions, and trends to the cumulative case. These 

projections are based on local, regional, and national trend data as well as likely changes to local, 

regional, and national economic and demographic conditions. Therefore, the projections include 

employment associated with the continuation of current patterns in OCS leasing activity and 

infrastructure development (refer to Chapter 4.1.1.23.1), as well as the continuation of trends in other 

industries important to the region. For example, these forecasts include the contributions of State oil and 

gas activities, renewable energy activities, coastal land use, tourism-related activities, and beach 

restoration projects using sand and gravel. Table 4-23 provides projections of employment, income, 

wealth, and business patterns for individual EIA’s; these data were obtained from the 2013 CEDDS data 

provided by Woods & Poole Economics, Inc. (2013). As discussed in the previous section, the OCS oil 

and gas industry comprises a modest percentage of the economies of most EIA’s.

Hurricanes

The impacts of a CPA proposed action on economic factors should be viewed in light of the ongoing 

risk of hurricanes in the Gulf of Mexico. Hurricanes can cause impacts to the OCS oil and gas industry 

by shutting down production in the immediate vicinity. Hurricanes can also cause disruptions to the 

functioning of economies and, if severe enough, can cause labor migrations to occur. Finally, hurricanes 

can cause damage to a number of base resources on which local economies depend.

Summary and Conclusion

The cumulative impacts of a CPA proposed action would be determined by the expected path of the 

economy and by the expected progression of the OCS oil and gas industry in upcoming years. The 

expected path of the overall economy is projected using the data provided by Woods and Poole 

Economics, Inc. (2013). The expected economic impacts of the OCS oil and gas industry in upcoming 

years are estimated using the mathematical model MAG-PLAN. The cumulative impacts of a CPA 

proposed action to the economies along the Gulf Coast are expected to be relatively small.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

BOEM conducted a search of Internet sources and of known data sources regarding economic factors. 

A study report that describes the most recent updates to BOEM’s economic model MAG-PLAN has 
4-194 Central Planning Area Lease Sales 235, 241, and 247 EIS

become available (Eastern Research Group, 2012). This report describes the methods used to reflect 

developments in new technologies, to incorporate costs for major activities, to incorporate detailed 

onshore distribution data, and to estimate onshore distributions of industry sectors at different levels of 

granularity. The MAG-PLAN’s estimates of the levels of employment impacts of lease sales are the same 

as was presented in the WPA 233/CPA 231 Supplemental EIS. Kaiser et al. (2013) provide additional 

information regarding the structures of the various components of the offshore drilling industry in the 

Gulf of Mexico. For example, this report describes the trends, major firms, and determinants of activity 

levels in both the drilling service market and the rig newbuild market.

Beaubouef (2013) and Dupre (2013) provide updates regarding the status of oil and gas exploration 

and development activities in the Gulf of Mexico. These reports find that exploration and development 

activities are increasing and that drilling has rebounded to levels seen prior to the Deepwater Horizon

explosion, oil spill, and response. These reports also forecast that exploration and development activities 

will continue to increase in future years. IHS Petrodata (2013) finds that its jackup day rate index for the 

Gulf of Mexico increased from 417 in October 2012 to 535 in October 2013. Workboat.com (2013) finds 

that day rates for offshore supply boats less than 200 deadweight tons increased from $5,840 in 

September 2012 to $11,736 in September 2013, while day rates for offshore crewboats under 170 feet 

long increased from $3,410 in September 2012 to $5,180 in September 2013.

The U.S. Energy Information Administration has also released its Annual Energy Outlook 2013

(USDOE, Energy Information Administration, 2013b). This report provides forecasts regarding a wide 

variety of issues related to energy markets. For example, this report provides forecasts of the levels of oil 

and gas production that will occur in Gulf offshore waters in future years. In its reference scenario, this 

report forecasts that Gulf offshore oil production will increase from 1.32 MMbbl per day in 2012 to 

1.40 MMbbl per day in 2013 and 1.51 MMbbl per day in 2014. This report forecasts that Gulf offshore 

natural gas production will decrease from 2.15 Tcf per day in 2012 to 1.89 Tcf per day in 2013 and 

1.79 Tcf per day in 2014. These production trends are driven by many factors, including price pressures 

arising from increasing onshore natural gas production (Humphries, 2013). Future production will also 

be influenced by a variety of factors that could affect oil and gas prices, such as the potential for increased 

energy production in Mexico that could arise from reforms of its energy sector (Hill, 2013).

The impacts of a proposed CPA lease sale and the OCS Program should be viewed in the context of 

overall economic conditions. In Table 4-8, data from Woods and Poole Economics, Inc. (2013) is used to 

generate forecasts of overall employment in EIA’s during the life of activities that would arise from a 

proposed CPA lease sale. Woods and Poole Economics, Inc. (2013) is also used to forecast various 

demographic variables; refer to Chapter 4.1.1.23.2 for more information regarding demographics. 

There remains some incomplete or unavailable information that may be relevant to reasonably

foreseeable impacts on economic factors. This information relates to the ultimate economic effects of the 

Deepwater Horizon oil spill, as well to gradual changes that may be made to MAG-PLAN over time. 

Given the available data that have been released, as described in this chapter, BOEM believes that this 

incomplete or unavailable information is not essential to a reasoned choice among alternatives. This is 

because this information is not expected to significantly change BOEM’s estimates of the routine, 

accidental, or cumulative impacts of a proposed CPA lease sale.

4.1.1.23.4. Environmental Justice

BOEM has reexamined the analysis for environmental justice presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

below. No new significant information was discovered that would alter the impact conclusion for 

environmental justice presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

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

CPA proposed action are presented in Chapters 4.2.1.23.4.2 and 4.2.1.23.3 of the 2012-2017 WPA/CPA 

Multisale EIS, and updated information is provided in Chapter 4.2.1.23.4 of the WPA 233/CPA 231 

Supplemental EIS. A CPA proposed action’s incremental contribution to the cumulative impacts is 

presented below. Any new information that has become available since those documents were published 

is presented below. A detailed description of environmental justice can be found in Chapter 4.2.1.23.4.1 
Description of the Environment and Impact Analysis 4-195

of the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.23.4 of 

the WPA 233/CPA 231 Supplemental EIS.

The oil and gas industry and its associated support sectors are interlinked and widely distributed along 

the Gulf Coast. Offshore OCS oil- and gas-related industry operations within the CPA may utilize 

onshore facilities located within the WPA, CPA, or both planning areas. In accordance with NEPA and 

the Executive Orders, BOEM must provide opportunities for community input during the NEPA process. 

Minority and low-income populations are provided the same opportunities as other communities to 

engage in the decisionmaking process.

Impacts of Routine and Accidental Events

The following routine activities associated with proposed CPA Lease Sales 235, 241, and 247 could 

potentially affect environmental justice: potential infrastructure changes/expansions including fabrication 

yards, support bases, and onshore disposal sites for offshore waste; increased commuter and truck traffic; 

and employment changes and immigration. An analysis of the routine impacts of a CPA proposed action 

on environmental justice can be found in Chapter 4.2.1.23.4.2 of the 2012-2017 WPA/CPA Multisale 

EIS, and updated information is provided in Chapter 4.2.1.23.4 of the WPA 233/CPA 231 Supplemental 

EIS.

Because of the existing extensive and widespread support system for OCS oil- and gas-related 

industry and the associated labor force, the effects of routine events related to a CPA proposed action are 

expected to be widely distributed and to have little impact. This is because a CPA proposed action is not 

expected to significantly change most of the existing conditions, such as traffic or the amount of 

infrastructure. Where such change might occur is impossible to predict but, in any case, it would be very 

limited. Because of Louisiana’s extensive oil-related support system, that State is likely to experience 

more employment effects related to a CPA proposed action than are the other coastal states, and because 

of the concentration of this system in Lafourche Parish, that parish is likely to experience the greatest 

benefits from employment benefits and burdens from traffic and infrastructure demand. Impacts related 

to a CPA proposed action on minority and low-income populations are expected to be primarily economic 

in nature and to have a limited but positive effect on low-income and minority populations because a CPA 

proposed action would contribute to the sustainability of current industry and related support services. 

Given the existing distribution of the industry and the limited concentrations of minority and low-income 

peoples adjacent to the OCS infrastructure (Chapter 4.2.1.23.4 of the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS) (Kaplan, et al., 2011), a CPA proposed action is not 

expected to have a disproportionate effect on these populations, even in Lafourche Parish.

Accidental events with impact-producing factors that may be associated with a CPA proposed action 

that could affect environmental justice include oil spills, vessel collisions, and chemical/drilling-fluid 

spills. These factors could affect environmental justice through direct exposure to oil, dispersants, 

degreasers, and other chemicals that can affect human health; decreased access to natural resources due to 

environmental damages, fisheries closures, or wildlife contamination; and proximity to onshore disposal 

sites used in support of oil and chemical spill cleanup efforts. A detailed impact analysis of the accidental 

impacts that may be associated with proposed CPA Lease Sales 235, 241, and 247 on environmental 

justice can be found in Chapter 4.2.1.23.4.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated 

information is provided in Chapter 4.2.1.23.4 of the WPA 233/CPA 231 Supplemental EIS.

Chemical and drilling-fluid spills may be associated with exploration, production, or transportation 

activities that result from a CPA proposed action. Low-income and minority populations might be more 

sensitive to oil spills in coastal waters than is the general population because of their dietary reliance on 

wild coastal resources, their reliance on these resources for other subsistence purposes such as sharing and 

bartering, their limited flexibility in substituting wild resources with purchased ones, and their likelihood 

of participating in cleanup efforts and other mitigating activities. Little is known about subsistence along 

the Gulf Coast, and BOEM is currently funding a study to better document subsistence in the region. 

BOEM’s subject-matter experts have utilized available, credible information for this analysis. Although 

most criteria related to environmental justice may not be essential to a reasoned choice among 

alternatives, subsistence impacts may be essential. Nevertheless, subsistence research is pending and 

outcomes will not be available within the timeline contemplated in the NEPA analysis of this 

Supplemental EIS. What credible information is available was applied using accepted methodologies. 

BOEM will continue to seek additional information as it becomes available and bases this analysis on the 
4-196 Central Planning Area Lease Sales 235, 241, and 247 EIS

best information currently available. With the exception of a low-probability catastrophic accidental 

event, such as the Deepwater Horizon explosion, oil spill, and response, which is not reasonably 

foreseeable and not part of a CPA proposed action, the impacts of oil spills, vessel collisions, and 

chemical/drilling fluid spills are not likely to be of sufficient duration to have adverse and 

disproportionate long-term effects for low-income and minority communities in the analysis area.

An event like the Deepwater Horizon explosion, oil spill, and response, which is not reasonably 

foreseeable and not part of a CPA proposed action, potentially could have adverse and disproportionate 

health effects for low-income and minority populations in the analysis area; however, to date, there has 

been little concrete evidence that such effects have occurred (Brown et al., 2011; Dickey, 2012; King and 

Gibbons, 2011; Middlebrook et al., 2011; U.S. Dept. of Labor, OSHA, 2010a and 2010b), although there 

is some dispute in the scientific community about proper risk assessment standards in seafood 

contamination research (Rotkin-Ellman et al., 2012; Rotkin-Ellman and Soloman, 2012). Whether or not 

disproportionate long-term health impacts to low-income and minority populations will occur is 

unknown, although scientific research continues.

The Gulf Coast Claims Facility was replaced by a Court Supervised Settlement Program that has been 

in operation since June 4, 2012 (Gulf Coast Claims Facility, 2012). An Economic and Property Damages 

Settlement was reached in early 2012 and includes the following types of claims: seafood compensation; 

business economic loss; individual economic loss; loss of subsistence; vessel physical damage; Vessel-ofOpportunity charter payment; coastal real property damage; wetlands real property damage; and real 

property sales loss. A Medical Benefits Settlement was also reached in early 2012 and offers benefits to 

qualifying people who resided in the United States as of April 16, 2012, who were either “Clean-Up 

Workers” or who were residents in certain defined beachfront areas and wetlands (“Zones”) during 

certain time periods in 2010. On May 2, 2012, the Court granted preliminary approval for the settlement 

and ordered that the Court-supervised settlement program begin accepting claims on June 4, 2012. For 

economic and property damages, valid claims will be paid as they are approved. For medical claims, 

payments and other benefits will be distributed after the final approval of the settlement and any appeals 

are resolved. The official Court-authorized claims administration website can be found on the Deepwater

Horizon Claims Center website (Deepwater Horizon Claims Center, 2013a). Persons who filed a claim 

with the Gulf Coast Claims Facility for losses, such as subsistence, whose claims were rejected or who 

have not already accepted a final settlement from British Petroleum, may file a new claim with the 

Deepwater Horizon Claims Center (Deepwater Horizon Claims Center, 2013b).

While economic impacts were partially mitigated by employers retaining employees for delayed 

maintenance or through the Gulf Coast Claims Facility Program’s emergency funds, the physical and 

mental health effects to both children and adults within these populations could potentially unfold for 

many years. As studies of past oil spills have highlighted, different cultural groups can possess varying 

capacities to cope with these types of events (Palinkas et al., 1992). Likewise, some low-income and/or 

minority groups may be more reliant on natural resources and/or less equipped to substitute contaminated 

or inaccessible natural resources with private market offerings. Because lower-income and/or minority 

populations may live near and may be directly involved with spill cleanup efforts, the vectors of exposure 

can be higher for them than for the general population, increasing the potential risks of long-term health 

effects. The post-Deepwater Horizon’s human environment remains dynamic, and BOEM will continue 

to monitor these populations over time and to document short- and long-term impacts. BOEM has funded 

a study on the social impacts of the oil spill. This study is currently ongoing and explores impacts 

through a two-pronged approach that involves ethnographic fieldwork combined with demographic 

analysis. The long-term impacts of the Deepwater Horizon explosion, oil spill, and response will become 

clearer as time allows the production of peer-reviewed research and targeted studies that determine those 

impacts.

The types of accidental events (smaller, shorter time scale) that are likely to result from a CPA 

proposed action may affect low-income and/or minority populations more than the general population, at 

least in the shorter term. These higher risk groups may lack the financial or social resources and may be 

more sensitive and less equipped to cope with the disruption these events pose. These smaller events, 

however, are not likely to significantly affect minority and low-income populations in the long term.
Description of the Environment and Impact Analysis 4-197

Summary and Conclusion 

BOEM has reexamined the analysis for environmental justice presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional information presented 

above. BOEM has determined that the additional information does not alter the impact conclusion for 

environmental justice because the information is currently inconclusive with regard to environmental 

justice issues and will remain so for an indefinite period of time. Therefore, the analysis and potential 

impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 

Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247.

Cumulative Impacts

Background/Introduction

The cumulative analysis considers impacts that may result from a CPA proposed action within the 

context of OCS oil- and gas-related and non-OCS oil- and gas-related, impact-producing factors for 

environmental justice. The OCS oil- and gas-related, impact-producing factors include OCS leasing, 

exploration, development, and production activities, and accidental events arising from these OCS 

activities. Non-OCS oil- and gas-related, impact-producing factors include human activities and natural 

events. The context in which people may find themselves and how that context affects their ability to 

respond to an additional change in the socioeconomic or physical environment is the heart of an 

environmental justice analysis. The OCS Program in the GOM is large and has been ongoing for more 

than 50 years, with established infrastructure, resources, and labor pools to accommodate it. That said, 

low-income and/or minority groups lacking financial, social, or environmental resources or practical 

alternatives may be more sensitive than other groups to the consequences of an oil spill, such as 

interruptions to municipal services or fisheries closures, and they may be less equipped to cope with these 

consequences. In studies on social disaster resiliency, variables such as income inequality can negatively 

impact a community’s ability to respond, and recover, from a disaster (Norris et al., 2008). Groups may 

be even less equipped to respond to these types of events if they are already in the process of recovering 

from a disaster, such as a hurricane. On the other hand, Cutter et al. (2008) found that previous disaster 

experience, defined as the number of paid disaster declarations, positively affected disaster resilience. 

This cumulative impact analysis examines how incremental additions to an established program from a 

CPA proposed action may potentially interact within these ongoing external impacts along the Gulf 

Coast. The oil and gas industry and its associated support sectors are interlinked and widely distributed 

along the Gulf Coast. Offshore OCS oil- and gas-related industry operations within the CPA may utilize 

onshore facilities located within the WPA, CPA, or both planning areas. In accordance with NEPA and 

the Executive Orders, BOEM must provide opportunities for community input during the NEPA process. 

Minority and low-income populations are provided the same opportunities as other communities to 

engage in the decisionmaking process.

OCS Oil- and Gas-Related Impacts 

A CPA proposed action and the OCS Program have the potential to adversely impact low-income, 

minority, and other environmental justice communities either directly or indirectly from onshore activities 

conducted in support of OCS exploration, development, and production and in onshore response activities 

associated with accidental events such as the Deepwater Horizon explosion, oil spill and response. 

Potential vectors for impacts include increases in onshore activity (such as employment, migration, 

commuter traffic, and truck traffic), additions to the infrastructure supporting this activity (such as 

fabrication yards, supply ports, and onshore disposal sites for offshore waste), and additional accidental 

events such as oil or chemical spills. BOEM estimates that production from a CPA proposed action will 

be 0.460-0.894 BBO and 1.939-3.903 Tcf of gas (Table 3-1). The cumulative oil and gas production in 

the CPA for the OCS Program (2012-2051) is estimated at 15.825-21.733 BBO and 63.347-92.691 Tcf of 

gas. Chapters 4.2.1.23.1.1 and 4.2.1.23.3.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapters 

4.2.1.23.1 and 4.2.1.23.3 of the WPA 233/CPA 231 Supplemental EIS describe the widespread and 

extensive OCS support system and associated labor force, as well as economic factors related to OCS 

activities. The widespread nature of the OCS oil- and gas-related infrastructure serves to limit the 

magnitude of effects that a single CPA proposed action or the overall OCS Program may have on any 
4-198 Central Planning Area Lease Sales 235, 241, and 247 EIS

particular community. Future lease sales will serve mostly to maintain the ongoing activity levels 

associated with the current OCS Program.

For most of the Gulf Coast, the OCS Program will result in only minor economic changes. Generally, 

effects will be widely yet thinly distributed across the Gulf Coast and will consist of slight increases in 

employment and few, if any, increases in population. Some places could experience elevated 

employment, population, infrastructure, and/or traffic effects because of local concentrations of 

fabrication and supply operations. Because of Louisiana’s extensive oil-related support system, it is 

likely to experience more employment effects related to a CPA proposed action than are the other coastal 

states. Because 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, it is likely to continue 

experiencing benefits from the OCS Program (Loren C. Scott & Associates, 2008). Except in Louisiana, 

the OCS Program is expected to provide little additional employment, although it will serve to maintain 

current activity levels, which is expected to be beneficial to Gulf region low-income and minority 

populations generally. Evidence also suggests that a healthy offshore petroleum industry also indirectly 

benefits low-income and minority populations. One Agency-funded study found income inequality in 

Louisiana decreased during the oil boom and increased with the decline (Tolbert, 1995).

A CPA proposed action will generate significant new infrastructure demand. Pipeline shore facilities 

are small structures, such as oil metering stations, associated with pipeline landfalls. In the Gulf of 

Mexico region, there are 129 OCS oil- and gas-related pipeline landfalls and 53 OCS oil- and gas-related 

pipeline shore facilities in the GOM region (Table 4-24). Chapter 3.1.2 discusses projected new coastal 

infrastructure that may result from a CPA proposed action, including the potential need for the 

construction of new facilities and/or the expansion of existing facilities. Each OCS oil- and gas-related 

facility that may be constructed onshore must receive approval by the relevant Federal, State, and local 

agencies. Each onshore pipeline must obtain similar permit approval and concurrence. BOEM assumes 

that all such approval would be consistent with appropriate land-use plans, zoning regulations, and other 

Federal/State/regional/local regulatory mechanisms. Should a conflict occur, BOEM assumes that 

approval would not be granted or that appropriate mitigating measures would be enforced by the 

responsible political entities, such as USEPA, the Louisiana Department of Natural Resources, the 

Louisiana Department of Environmental Quality, or the Alabama Department of Environmental 

Management.

The Gulf Coast region as a whole is not homogenous, but there are several potentially vulnerable 

ethnic and socioeconomic groups, some residing in enclaves, dispersed throughout Gulf of Mexico OCS 

economic impact areas. Ten counties/parishes possess high concentrations of oil-related infrastructure, 

but they do not generally include high concentrations of minority and low-income populations. In the 

10 high infrastructure concentration counties/parishes, many of the low-income and minority populations 

reside in large urban areas where the complexity and dynamism of the economy and labor force preclude 

measurable lease sale-level or programmatic-level OCS effects (Kaplan et al., 2011). A list of the 

counties and parishes in the Gulf of Mexico region with high, medium, and low concentrations of OCS 

oil- and gas-related infrastructure can be found in Table 4-25. 

Two local infrastructure issues analyzed in Chapter 4.2.1.23.4.1 of the 2012-2017 WPA/CPA 

Multisale EIS and Chapter 4.2.1.23.4 of the WPA 233/CPA 231 Supplemental EIS could possibly have 

related environmental justice concerns: traffic on LA Hwy 1 and the ongoing Port Fourchon expansion. 

This analysis concludes that the minority and low-income populations of Lafourche Parish will share the 

negative impacts of the OCS Program with the rest of the population. However, most effects are expected 

to be economic and positive, as in the areas of job creation and economic stimulation. Improvements to 

the Port Fourchon highway system are ongoing and upon completion will alleviate many of the associated 

transportation issues.

Impacts, including how communities respond to fluctuations in industry activity, vary from one 

coastal community to the next. Expansion or contraction of offshore or onshore oil and gas activity has 

produced moderate impacts in some communities, whereas other communities have dealt with episodes of 

rapid industry change with negligible to minor impact. Overall, OCS programmatic impacts to 

environmental justice over the next 40 years will likely represent a very small proportion of the 

cumulative impacts of all activities that affect environmental justice.

Based on operator data provided in filed plans, BOEM estimates that there is an average of 2,000 ft3

(57 m3

) of trash and debris generated per exploration well drilled, 102 ft3 (3 m3) of trash and debris 

generated per development well drilled, and 1,000 ft3 (28 m3

) of trash and debris generated per year per 
Description of the Environment and Impact Analysis 4-199

manned platform of its 25-year life (Dismukes et al., 2007). A single CPA proposed action usually 

represents <1 percent of the total current permitted landfill capacity in a GOM economic impact area. 

Because of technological improvements on how waste is compacted, landfill capacity has increased, with 

Texas landfills having increased useful life by 19 years from the mid-1990’s to 2005. Drilling muds and 

wastewater streams can be used as landfill cover, and landfills will often accept these materials at a 

reduced price or even at no charge (The Louis Berger Group, Inc., 2004). The occurrence of hazardous 

offshore, oil-field waste is minimal and infrequent. Industry representatives contracted for a BOEM study 

indicated that the need for hazardous storage could occur as infrequently as once in 5 years for a typical 

offshore facility with drilling and production activities (Dismukes et al., 2007). Table 4-26 lists where 

existing waste sites are located and the amount of waste that was generated by the Deepwater Horizon

explosion, oil spill, and response and that was distributed between Gulf landfills and waste processing 

facilities. Argonne National Laboratory reported that there are 46 waste management facilities that 

service the oil and gas industry along the GOM, with 18 in Louisiana, 18 in Texas, 5 in Mississippi, 4 in 

Alabama, and 1 in Florida (Puder and Veil, 2006). Because of existing capacity, no new waste disposal

sites are projected for the cumulative case (The Louis Berger Group, Inc., 2004). Therefore, no changes 

in impacts to minority and low-income communities are expected.

While the long-term social impacts of the Deepwater Horizon explosion, oil spill, and response have 

yet to be determined, anecdotal evidence from media coverage and early survey studies suggested the 

possibility of trends that might disproportionately affect low-income and minority communities for some 

time to come. A phone survey conducted by a team of Louisiana State University sociologists found that 

nearly 60 percent of the 925 coastal Louisiana residents interviewed reported being almost constantly 

worried by the Deepwater Horizon explosion, oil spill, and response (Lee and Blanchard, 2010). Studies 

of residents near past oil spills (such as the Exxon Valdez in Prince William Sound, Alaska) have noted 

impacts to social cohesion and increased distrust in government and other institutions, which contributed 

to community anxiety (Tuler et al., 2009). Refer to Appendix B for a detailed discussion of a lowprobability, high-impact catastrophic oil spill.

Cumulative effects from oil-spill events on social organization could include fragmentation of the 

family, cooperation, sharing, and subsistence availability. Long-term effects on wild resource harvest 

patterns might also be expected. While acute health effects from oil-spill events have been somewhat 

studied, the long-term impacts from exposure are unknown (Aguilera et al., 2010; Meo, 2009; Morita 

et al., 1999; Sathiakumar, 2010). The National Institutes of Health’s long-term health surveillance studies 

of possible long-term health effects from exposure to either the Deepwater Horizon explosion, oil spill, 

and response’s oil or dispersants, such as the possible bioaccumulation of toxins in tissues and organs, are 

ongoing. The potential for the long-term human health effects remains largely unknown. Participants in 

the Deepwater Horizon “Vessels of Opportunity” program, which recruited local boat owners (including 

Cajun, Houma Indian, and Vietnamese fishermen) to assist in cleanup efforts, may be one of the exposed 

groups. African Americans are thought to have made up a high percentage of the cleanup workforce. In 

Gulf coastal areas, low-income and minority groups are heavy subsistence users of local seafood. Worker 

and shoreline monitoring data indicate that the concentrations of oil and dispersants to which low-income 

and minority communities may have been exposed are unlikely to result in adverse health effects (King 

and Gibbons, 2011; Middlebrook et al., 2011; U.S. Dept. of Labor, OSHA, 2010a and 2010b). One 

concern is that heavy subsistence users may face higher than expected, and potentially harmful, exposure 

rates to PAH’s from the Deepwater Horizon explosion, oil spill, and response. However, fisheries

closures may have temporarily limited access to subsistence foods, thereby also reducing the potential of 

oil dispersant exposure, especially since fisheries were not reopened until testing indicated that the waters 

were safe for fishing. Extensive seafood testing for PAH’s and dispersant compounds found levels that 

were within the risk assessment protocol established by the U.S. Food and Drug Administration, NOAA, 

and the Gulf Coast States (Brown et al., 2011; Dickey, 2012). It should be noted that there is some 

dispute within the scientific community over the validity of the risk assessment protocol that was used, 

and there is concern that the levels of concern established by the protocol may have underestimated the 

risk from seafood contaminants among vulnerable populations such as pregnant women and children 

(Rotkin-Ellman et al., 2012; Rotkin-Ellman and Soloman, 2012). The U.S. Food and Drug 

Administration defended the protocol as valid (Dickey, 2012). Future long-term studies may help to 

resolve the dispute. For purposes of this Supplemental EIS, BOEM has conservatively assumed that fish 

consumption remains a potential pathway for impacting the local population in the event of a lowprobability catastrophic event. 
4-200 Central Planning Area Lease Sales 235, 241, and 247 EIS

The National Institutes of Health’s proposed study, known as the Gulf Long-Term Follow-Up Study 

(GuLF STUDY), is expected to provide a better understanding of the long-term and cumulative health 

impacts, such as the consequences of working close to a spill and of consuming contaminated seafood. 

The GuLF STUDY will monitor oil-spill cleanup workers for 10 years. The GuLF STUDY has closed 

enrollment with nearly 33,000 participants. Of the study participants, 82 percent live in the five Gulf 

Coast States and 18 percent are from other states. Minority and low-income persons comprise 38 percent 

and 26 percent, respectively, of study participants. All of the participants either helped with the cleanup 

effort (74%) or were trained but did not actually help with the cleanup (26%) (National Institute of 

Environmental Health Sciences, 2013).

Studies that seek to understand the short- and long-term impacts of the Deepwater Horizon explosion, 

oil spill, and response are ongoing regarding environmental justice concerns. BOEM modified an 

ethnicity study immediately after the oil spill started and added an oil-spill impact component, which 

allowed them to task ethnographers who were already on the ground in Louisiana and Mississippi. In 

mid-2010, BOEM also funded a study to document subsistence in the region. In 2012, BOEM kicked-off 

a study on the social impacts of the oil spill and explores impacts through a two-pronged approach that 

involves ethnographic fieldwork combined with demographic analysis. The NRDA process may also 

help us to understand issues relating to subsistence and other indigenous reliance on natural resources.

The National Institute of Environmental Health Sciences awarded a 5-year $7.85 million grant to a 

consortium of university researchers and regional community groups; the consortium will be led by the 

University of Texas Medical Branch at Galveston. The study, known as Gulf Coast Health Alliance: 

Health Risks Related to the Macondo Spill (GC-HARMS), will be focused on gaining an understanding of 

the long-term health effects attributable to the Deepwater Horizon oil spill. The GC-HARMS will 

examine and analyze human exposure and seafood contamination by “measuring the distribution of 

potentially carcinogenic petrogenic polycyclic aromatic hydrocarbons (PAH) present in weathered oil” 

(University of Texas Medical Branch, 2013). University researchers will work closely with community 

partners using a Community-Based Participatory Research approach. The community groups will 

connect researchers with local fishermen who will be trained to do sampling from not only their 

commercial catches but also from their bycatch, which they consume and frequently share or barter 

through extended families. They will also serve as partners in the effort to determine how seafood is 

distributed in local subsistence communities. The GC-HARMS will also include an outreach effort to 

inform Gulf Coast residents of the study’s findings and other relevant research (University of Texas 

Medical Branch, 2013).

The Deepwater Horizon explosion, oil spill, and response stimulated increased community outreach 

projects. For example, the Mississippi Coalition for Vietnamese-American Fisher Folks and Families 

(MCVAFF) continued its extensive post-oil spill outreach efforts by helping to facilitate a NRDA/Early 

Coastal Restoration training in 2012 that over 80 Vietnamese-American fisher folks attended. The 

MCVAFF provided qualified interpreters and translated materials to ease communication throughout the 

training. A series of early Coastal Restoration public meetings in the coastal counties of Mississippi were 

also widely attended by fisher folks who were able to participate in the process and present ideas for 

coastal restoration projects (USEPA, 2013d). 

Minority and low-income populations who may have a claim against the responsible party have faced 

a difficult claim-resolution process that evolved in the post-spill environment. The Gulf Coast Claims 

Facility was replaced by a Court Supervised Settlement Program that started operations on June 4, 2012 

(Gulf Coast Claims Facility, 2012). An Economic and Property Damages Settlement was reached in early 

2012 and includes the following types of claims: seafood compensation; business economic loss; 

individual economic loss; loss of subsistence; vessel physical damage; Vessel-of-Opportunity charter 

payment; coastal real property damage; wetlands real property damage; and real property sales loss. A 

Medical Benefits Settlement was also reached in early 2012 and offers benefits to qualifying people who 

resided in the United States as of April 16, 2012, who were either “Clean-Up Workers” or who were 

residents in certain defined beachfront areas and wetlands (“Zones”) during certain time periods in 2010. 

The official Court-authorized claims administration website can be found on the Deepwater Horizon

Claims Center website (Deepwater Horizon Claims Center, 2013a). Persons who filed a claim with the 

Gulf Coast Claims Facility for losses, such as subsistence, whose claims were rejected, or who have not 

already accepted a final settlement from British Petroleum may file a new claim with the Deepwater 

Horizon Claims Center (Deepwater Horizon Claims Center, 2013b).
Description of the Environment and Impact Analysis 4-201

Whether or not long-term impacts to low-income and minority populations will occur is unknown. 

As studies of past oil spills have highlighted, different cultural groups can possess varying capacities to 

cope with these types of events (Palinkas et al., 1992). Likewise, some low-income and/or minority 

groups may be more reliant on natural resources and/or less equipped to substitute contaminated or 

inaccessible natural resources with private market offerings. Because lower-income and/or minority 

populations may live near and may be directly involved with spill cleanup efforts, the vectors of exposure 

can be higher for them than for the general population, increasing the potential risks of long-term health 

effects. BOEM will continue to monitor these populations over time and to document short- and longterm impacts. Information regarding the long-term impacts of the Deepwater Horizon explosion, oil spill, 

and response remains incomplete, and scientific research is ongoing. Information from the NRDA 

process is unavailable and unobtainable at this time. In its place, BOEM’s subject-matter experts have 

used credible information that is available and applied it using accepted socioeconomic methodologies. 

BOEM will continue to seek additional information as it becomes available and bases the previous 

analysis on the best information currently available.

In addition to oil-spill events, public health also may be affected by routine OCS oil- and gas-related 

activities, though it is difficult to determine whether the impact is directly or indirectly related to oil and 

gas activities on the OCS since there are also extensive oil and gas activities onshore. Public health is a 

unique factor for this cumulative analysis because it is applicable to either or both OCS oil- and gasrelated and non-OCS oil- and gas-related analyses. The complexity of making that determination, teasing 

out which does what and where, is far beyond the scope of this analysis.

The Natural Resources Defense Council and the National Disease Clusters Alliance identify and track 

disease clusters in the U.S. An unusually large number of people sickened by a disease in a certain place 

and time is known as a “disease cluster” (Natural Resources Defense Council and National Disease 

Clusters Alliance, 2011). The underlying causes of a disease cluster can be genetic, environmental, or 

both. The State of Louisiana’s Center for Environmental Health defines an environmental disease cluster 

when evidence of a known connection between the hazard and the disease or health outcome of concern is 

established (State of Louisiana, Dept. of Health and Hospitals, 2008). The Natural Resources Defense 

Council and the National Disease Clusters Alliance identified disease clusters in 13 states, with four 

clusters in Louisiana and three clusters in Florida. The four locations in Louisiana include Mossville in 

Calcasieu Parish, Amelia in St. Mary Parish, Coteau in Iberville Parish, and New Orleans in Orleans 

Parish. The exact cause of these clusters is unknown, but experts suspect environmental contaminants. 

The Agency for Toxic Substances and Disease Registry identified a cluster of breast cancer in an urban 

census tract at the Agricultural Street Landfill Superfund Site in New Orleans in a 2003 study. According 

to the Agency for Toxic Substances and Disease Registry, the site and neighborhood are contaminated 

with metals, PAH’s, VOC’s, and pesticides due to a contaminated landfill that operated from 1909 to 

1962 and then was covered with dirt and used as a site for residential development in 1976. The area was

designated a hazardous waste site in 1993. From 1986 through 1987, researchers from Louisiana State 

University Medical School identified a cluster of neuroblastoma, a type of brain cancer adjacent to a 

marine shale processor plant in Amelia, located in St. Mary Parish, Louisiana. There was insufficient 

data to link a hazardous waste incinerator at the marine shale processor plant, but in 2007 the owners paid 

the State government a settlement to close and remediate the site. In Florida, Palm Beach, Collier, and 

Manatee Counties each have confirmed disease clusters. Loxahatchee, Florida, located in Palm Beach 

County, has a pediatric brain cancer cluster thought to be caused by spills of chemicals, solvents, and 

pesticides from a rocket and jet engine company. Immokalee, Florida, located in Collier County, is site of 

a birth defect disease cluster believed to be caused by an agricultural corporation that used six of the most 

dangerous pesticides in excessive levels. Tallevast, Florida, located in Manatee County, is home to a 

cancer disease cluster caused by prior long-term use of contaminated groundwater that resulted from 

improper disposal of a cancer-causing solvents such as trichloroethylene at a machine parts 

manufacturing plant (Natural Resources Defense Council and the National Disease Clusters Alliance, 

2011). Disease clusters are included here because even though a direct cause-effect relationship has not 

been established between OCS activities and the occurrence of these clusters, it cannot be stated 

emphatically that OCS activities have or have not been a contributing factor to some of these problems. 

Clearly, impacts to public health can occur because of non-OCS and OCS oil- and gas-related activities 

whether from marine shale processors or waste brought to landfills or from environmental contamination 

from non-OCS oil- and gas-related industrial concerns or upstream and downstream facilities attached to 

either or both onshore and offshore oil and gas activities. The most important question, and one that has 
4-202 Central Planning Area Lease Sales 235, 241, and 247 EIS

proved impossible to answer, is how much of actual OCS oil- and gas-related activities, i.e., offshore 

activity in Federal waters, may contribute to these problems. This cannot be definitively determined. 

There are numerous non-OCS oil- and gas-related activities that also contribute to these public health 

problems, such as State oil and gas activities, both onshore and offshore in State waters, as well as other 

industrial activities onshore that have produced various landfill-destined waste products and/or discharged 

toxic liquid waste and air emissions.

Due to the distance of OCS oil- and gas- related activities offshore, routine events related to a CPA 

proposed action would not be expected to directly affect public health in these communities, though it is 

not unlikely that members of these communities could participate in cleanup efforts if there was an oilspill event. An environmental justice analysis seeks to identify populations that, through a variety of 

mechanisms, may become disproportionately impacted by a CPA proposed action and associated 

activities. Research like this suggests that there may be a correlation between downstream oil and gas 

processing (after any OCS Program-related oil and gas comes ashore) and diminished health in adjacent 

populations. As a result, communities appearing to have disease clusters are probably more sensitive to 

potential impacts in a cumulative scenario.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related impacts cover a wide range of potential impact-producing factors, 

including all human activities and natural events and processes that are not related to OCS oil- and gasrelated activities. Some of the human activities that may disproportionately affect low-income and 

minority populations include, but are not limited to, the following: urbanization; pollution (air, light, 

noise, garbage dumping, and contaminated runoff); commercial/residential/agricultural development; 

zoning ordinances; community development strategies (multi-purpose, single-use); expansions to the 

Federal, State and local highway systems; expansions to regional port facilities; military activities; 

demographic shifts (in-migration, out-migration); economic shifts on the national, State and local levels 

(job creation and job losses); military activities; educational systems (quality, availability, expansions or 

contractions); family support systems (availability, proximity and quality of mental health services, foster 

care, charity hospital systems, addictive disorders rehabilitation centers, planned parenthood, head start 

programs, etc.); governmental functions (municipal waterworks systems, sewage systems, tax structures, 

revenue collection, law enforcement, fire protection, traffic control, voting processes, legislative 

processes, court procedures and processes, real estate property assessments, construction permits, 

environmental protection services, land-use permits, etc.); contraction or expansion of the tourism

industry; financial system (banking and investment services); State renewable energy activities; river 

channelization, dredging of waterways; State oil and gas activity; existing infrastructure associated with 

downstream activities such as petrochemical processing; and public health.

Urbanization may disproportionately impact low-income and minority populations who make up the 

larger portion of an urban population and thus may be subjected to high levels of pollution (air, light, 

noise, litter/dumping) that often exist in urban areas. Commercial and residential developments may 

produce a disproportionate affect if the low-income and minority population’s interests are not adequately 

represented at public hearings. Agricultural development has often contributed (and may continue to 

contribute) to the loss of wetlands and deforestation, which is a problem for subsistence populations who

are often low-income and minority and depend on the wetlands and forests for their subsistence activities. 

When Federal, State, and local highway systems and regional port facilities are expanded, there is a 

tradeoff between the benefits of expansion and the potential negative impact to the local environment. 

Low-income and minority populations share in those positive and negative impacts. Likewise, when the 

Federal, State, and/or local economic conditions deteriorate (job losses), low-income and minority 

populations with less financial resources may bear the brunt of the impact. Military activities such as 

military base closures resulting in job losses and the resulting direct, indirect, and induced economic 

impacts for surrounding communities, as well as infrastructure expansion at military bases, may produce 

both negative and positive effects on nearby low-income and minority populations. Demographic shifts, 

such as out-migration, which often occur with major economic downturns, affect whole communities. 

However, economic upturns and demographic in-migration may benefit low-income and minority 

populations. 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 
Description of the Environment and Impact Analysis 4-203

towns, and the availability of special education services in the public schools. All of these factors 

contribute to the quality of the educational system in these communities. Another very important nonOCS oil- and gas-related, impact-producing factor for low-income and minority populations involves 

family support services systems, namely their availability, proximity, and quality. Social services such as 

mental health support, charity hospitals, addictive disorder rehabilitation, foster care, head start programs, 

and planned parenthood are often hard to find in rural areas, but these services may be more accessible in 

larger cities, towns, and urban areas.

Other human activities that also may have disproportionate positive or negative impacts on lowincome and minority populations are related to local, State, and Federal government functions, which are 

numerous and expansive. Two of the more crucial government functions for basic community 

functioning involve municipal waterworks and sewage systems. If these are not maintained in good 

condition with adequate capacity, low-income and minority populations may suffer disproportionate 

negative impacts. 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 effects are felt by all those connected, but the effects may 

be disproportionately felt by low-income and minority populations in any area that they may constitute a 

larger presence. These same populations may experience disproportionate negative effects related to the 

financial system, namely access to loans, investment planning, and insurance. State renewable energy 

programs are non-OCS oil- and gas-related and may also provide a vector for disproportionate impacts 

due to their potential placement on or near fishing and hunting grounds that are crucial for subsistence 

users. River channelization and dredging of other waterways are also potential negative impacts for lowincome and minority populations where they may have traditionally fished and tended oyster beds.

Additionally, onshore human activities conducted in support of State oil and gas exploration, 

development, and production have the potential to adversely impact low-income, minority, and other 

environmental justice communities either directly or indirectly. Louisiana, Mississippi, and Alabama’s 

jurisdiction over mineral resources extends 3 nmi (3.5 mi; 5.6 km) from the shore; Texas and the west 

coast of Florida’s jurisdiction over the seabed extends out 9 nmi (10.4 mi; 16.7 km). The annual gas 

production from Alabama State waters has ranged from 150 to 200 billion cubic feet or approximately 

50 percent of the State’s total gas production (State of Alabama, n.d.). While offshore leasing in shallow 

waters is in general decline, states like Louisiana are attempting to incentivize increased activity closer to 

the shore. In 2006, the Louisiana Legislature authorized the Louisiana Department of Environmental 

Quality to implement an Expedited Permit Processing Program, which has so far resulted in a 55-percent 

reduction in coastal permitting time (State of Louisiana, Dept. of Natural Resources, 2009). In November 

2010, Louisiana voters passed the Louisiana Natural Resource Severance Tax Amendment, which 

effectively decreases the amount of taxes retained by the State on the severance of natural resources, but it 

increases what can be collected by the parishes where resources are extracted (State of Louisiana, 2010). 

Whether this measure will increase individual parishes’ incentive to encourage production closer to the 

coast is still unknown.

State offshore oil and gas programs pose the same potential issues as does the OCS Program, 

although since State leases are closer to land, their petroleum-related activities are generally viewed as 

having greater potential for directly impacting coastal communities. BOEM assumes that sitings of any 

future facilities associated with State programs will 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 

(that can be used to purchase better equipment for subsistence), better health care, and improved 

educational facilities. While industrialization generally leads to a shift in community organization and 

cultural development, the offshore oil and gas industry and its concentrated work schedule has been more 

accommodating of “traditional” activities, such as trapping and fishing, during their time at home (Luton 

and Cluck, 2004).

Existing onshore infrastructure associated with petrochemical processing, including refineries (such 

as polyvinyl plants) and the production of petroleum-based goods, poses potential health and other related 

risks to minority and low-income communities. Expectations for new gas processing facilities being built 

during the period 2012-2051 as a direct result of the OCS Program are dependent on long-term market 

trends that are not easily predictable over the next 40 years. Existing facilities will experience equipment 

switch-outs or upgrades during this time. The marginal contribution of a CPA proposed action does not 
4-204 Central Planning Area Lease Sales 235, 241, and 247 EIS

change the estimate. The geographic distribution of projected gas processing facilities differs markedly 

from the current distribution. BOEM cannot predict and does not regulate the siting of future gas 

processing plants. BOEM assumes that sitings of any future facilities will be based on the same 

economic, logistical, zoning, and permitting considerations that determined past sitings and that they will 

not disproportionately affect minority and low-income populations. An environmental justice study of 

industrial siting patterns in Jefferson, St. Bernard, and Lafourche Parishes in Louisiana (Hemmerling and 

Colten, 2003) found that “people appear to be moving into densely populated, largely industrial areas 

where the costs of rent are lower. In addition, people tend to be moving into newer housing.” This 

historical analysis revealed little evidence of systematic environmental injustice of various oil-related 

industries, with the demographic makeup of the communities changing after facilities arrived.

While human activities are extensive and nearly all-encompassing, there are a substantial number of 

natural events and processes that may be classified as non-OCS oil- and gas-related impacts and that are 

unassociated with OCS-based oil and gas activities. Some of the natural events and processes that lowincome and minority populations may be disproportionately 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; beach strandings; coastal erosion/subsidence; sealevel rise; and coastal storms.

Low-income and minority populations in the coastal region are often subsistence users, and many 

depend on the harvesting of oysters for either subsistence or financial income. There are a large number 

of African-American oyster harvesters in Plaquemines Parish, Louisiana, for example. The health of the 

oyster beds is critical to these populations. When degradation of oyster reefs occurs, it may negatively 

and disproportionately affect low-income and minority populations by decreasing the number of oysters 

that are able to harvest for economic and subsistence uses. Saltwater intrusion affects oyster reefs and the 

overall wetlands ecosystem, which is where these populations hunt and fish. In some places there is too 

much sediment deposited in waterways, and in others there is sediment deprivation; both of these serve to 

negatively impact the delicate ecosystem upon which these people depend. Barrier islands are very 

important to low-income and minority populations who make their living fishing these areas. The barrier 

islands in the regions have been migrating and eroding for decades. This natural process is one of the 

challenges faced in the region and contributes to cumulative effects. Low-income and minority 

populations may also be disproportionally affected by the negative impacts of fish kills, red tide, and 

beach strandings, which all may interfere with their use of the land for subsistence and economic 

purposes.

Coastal erosion and subsidence in some parts of the southeastern coastal plain serves to amplify the 

vulnerability of communities, infrastructure, and natural resources to storm-surge flooding (Dalton and 

Jones, 2010). Submergence in the Gulf 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 river channelization and canal dredging is a major cause of coastal habitat deterioration 

(Tiner, 1984; National Wetlands Inventory Group, 1985; Cox et al., 1997); refer to Chapter 4.2.1.4 of the 

2012-2017 WPA/CPA Multisale EIS for a detailed discussion of wetlands in the CPA. As discussed in 

Chapter 4.2.1.23.4.1 of the 2012-2017 WPA/CPA Multisale EIS, tropical storms may be the norm in the 

region, but low-income and minority communities may bear a larger burden than the general populations 

when the amount of coastal erosion resulting from those storms is considered. Native Americans, 

Vietnamese, Cajuns, African Americans, and other ethnic enclaves have all borne catastrophic losses in 

recent storm events. An estimated 4,500 Native Americans living on the southeast Louisiana coast lost 

their possessions to Hurricane Katrina, according to State officials and tribal leaders. Cajuns were also 

impacted by Hurricane Katrina, and especially by Hurricane Rita, whose 20-ft (6-m) storm surges flooded 

low-lying communities in Cameron, Calcasieu, and other coastal parishes (Kaplan et al., 2011). 

According to a USGS 5-year, post-Katrina survey, the wetland loss in Louisiana from all four storms 

(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 mi 2 (4,877 km2

) 

from 1932 to 2010 (Couvillion et al., 2010).

A U.S. Geological Survey study published in early 2013, Economic Vulnerability to Sea-Level Rise 

along the Northern U.S. Gulf Coast, applied a CEVI to the northern Gulf coastal region in order to 
Description of the Environment and Impact Analysis 4-205

measure economic vulnerability to sea-level rise. 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 Gulf 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).

Coastal erosion, subsidence, and sea-level rise can increase community vulnerability to future hazards 

and 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 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). 

Hurricanes, tropical storms, and other wind-driven tidal or storm events are a fact of life for 

communities living along the Gulf of Mexico coastal zone. For low-income and minority populations, 

however, the impacts of coastal storm events can be particularly profound because of factors like limited 

resources to evacuate or to mitigate hazards. Baseline conditions pertaining to environmental justice were 

reevaluated in light of recent hurricane activity in the Gulf of Mexico. The intensity and frequency of 

hurricanes in the Gulf 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). Impacts from future hurricanes and tropical storm events are uncertain. One study found that 

Galveston neighborhoods with higher proportions of renters, households in poverty, and minorities were 

more likely to have waited to evacuate the urbanized barrier island in advance of Hurricane Ike (Van 

Zandt et al., 2010). Municipal programs like the New Orleans Office of Homeland Security and Public 

Safety’s City Assisted Evacuation Plan are being implemented to help citizens who want to evacuate 

during an emergency but lack the capability to self-evacuate (City of New Orleans, n.d.). Hazard 

mitigation funds available through individual states and the Federal Emergency Management Agency also 

seek to mitigate potential damage to homes in flood zones throughout the Gulf. While hurricanes and 

tropical storms are inevitable, lessons learned from Hurricanes Katrina, Rita, Gustav, and Ike are shaping 

local and national policies as well as nongovernmental organizations efforts to protect low-income, 

minority, and other vulnerable communities.

In addition to coastal storms, public health also may be considered a non-OCS oil- and gas-related 

factor. Public health is a unique factor for this cumulative analysis because it is applicable to both OCS 

oil- and gas-related and non-OCS oil- and gas-related analysis. Problems that the affect public health 

may be cause by either or both non-OCS oil- and gas-related and OCS oil- and gas-related activities. The 

complexity of making that determination, teasing out which does what and where, is far beyond the scope 

of this analysis. The Natural Resources Defense Council and the National Disease Clusters Alliance 

identify and track disease clusters in the U.S. An unusually large number of people sickened by a disease 

in a certain place and time is known as a “disease cluster” (Natural Resources Defense Council and 

National Disease Clusters Alliance, 2011). The underlying causes of a disease cluster can be genetic, 

environmental, or both. The State of Louisiana’s Center for Environmental Health defines an 

environmental disease cluster when evidence of a known connection between the hazard and the disease 

or health outcome of concern is established (State of Louisiana, Dept. of Health and Hospitals, 2008). 

The Natural Resources Defense Council and the National Disease Clusters Alliance identified disease 

clusters in 13 states, with four clusters in Louisiana and three clusters in Florida. The four locations in 
4-206 Central Planning Area Lease Sales 235, 241, and 247 EIS

Louisiana include Mossville in Calcasieu Parish, Amelia in St. Mary Parish, Coteau in Iberville Parish, 

and New Orleans in Orleans Parish. The exact cause of these is unknown, but experts suspect 

environmental contaminants. The Agency for Toxic Substances and Disease Registry identified a cluster 

of breast cancer in an urban census tract at the Agricultural Street Landfill Superfund Site in New Orleans 

in a 2003 study. According to the Agency for Toxic Substances and Disease Registry, the site and 

neighborhood are contaminated with metals, PAH’s, VOC’s, and pesticides due to a contaminated landfill 

that operated from 1909 to 1962 and then was covered with dirt and used as a site for residential 

development in 1976. The area was designated a hazardous waste sight in 1993. From 1986 through 

1987, researchers from Louisiana State University Medical School identified a cluster of neuroblastoma, a 

type of brain cancer adjacent to a marine shale processor plant in Amelia, located in St. Mary Parish, 

Louisiana. There was insufficient data to link a hazardous waste incinerator at the marine shale processor 

plant, but in 2007 the owners paid the State government a settlement to close and remediate the site. In 

Florida, Palm Beach, Collier, and Manatee Counties each have a confirmed disease cluster. Loxahatchee, 

Florida, located in Palm Beach County, has a pediatric brain cancer cluster thought to be caused by spills

of chemicals, solvents, and pesticides from a rocket and jet engine company. Immokalee, Florida, located 

in Collier County, is site of a birth defect disease cluster believed to be caused by an agricultural 

corporation that used six of the most dangerous pesticides in excessive levels. Tallevast, Florida, located 

in Manatee County, is home to a cancer disease cluster caused by prior long-term use of contaminated 

groundwater that resulted from improper disposal of cancer-causing solvents such as trichloroethylene at 

a machine parts manufacturing plant. The complexity and inherent difficulty of investigating potential 

and suspected disease clusters often lead to inconclusive results. Scientific tools used to determine causeand-effect in small populations are limited (Natural Resources Defense Council and the National Disease 

Clusters Alliance, 2011). This discussion shows that impacts to public health can occur because of nonOCS oil- and gas-related and OCS oil- and gas-related activities whether they are from marine shale 

processors or waste brought to landfills or from environmental contamination from non-OCS oil- and gasrelated industrial concerns or upstream and downstream facilities attached to either or both onshore and 

offshore oil and gas activities.

Summary and Conclusion

The cumulative impacts of a CPA proposed action would occur within the context of other impactproducing factors for environmental justice. The OCS oil- and gas-related, impact-producing factors 

include OCS leasing, exploration, development, and production activities, and accidental events arising 

from these OCS activities. Non-OCS oil- and gas-related, impact-producing factors include human 

activities and natural events. Because of the presence of an extensive and widespread support system for 

the OCS and associated labor force, the OCS oil- and gas-related effects of the cumulative case are 

expected to be widely distributed and, except in Louisiana, little felt. In general, the cumulative OCS oiland gas-related effects are expected to be economic and to have a limited but positive effect on lowincome and minority populations. In Louisiana, these positive economic effects are expected to be 

greater. In general, who will be hired and where new infrastructure might be located is impossible to 

predict. Given the existing distribution of the OCS oil- and gas-related industry and the limited 

concentrations of minority and low-income peoples, a CPA proposed action and the cumulative OCS 

Program are not expected to have disproportionate high/adverse environmental or health effects on 

minority or low-income populations. Lafourche Parish will experience the most concentrated effects of 

cumulative OCS oil- and gas-related impacts. However, these groups are not expected to be differentially 

affected because the parish is not heavily low-income or minority and because the effects of road traffic 

and port expansion would not occur in areas of low-income or minority concentration.

In the Gulf coastal area, the contribution of a CPA proposed action and the OCS Program to the 

cumulative effects of all non-OCS oil- and gas-related activities and trends affecting environmental 

justice issues over the next 40 years are expected to be negligible to minor. The cumulative effects will 

be concentrated in coastal areas, and particularly Louisiana.. Most OCS Program effects are expected to 

be in the areas of job creation and the stimulation of the economy, and they are expected to make a 

positive contribution to environmental justice. The contribution of the cumulative OCS Program to the 

cumulative impacts of all factors affecting environmental justice is expected to be minor; therefore, the 

incremental contribution of a CPA proposed action to the cumulative impacts would also be minor. State 

offshore leasing programs in Alabama and Louisiana have similar, although more limited, effects due to 
Description of the Environment and Impact Analysis 4-207

their smaller scale. Cumulative effects from onshore infrastructure, including waste facilities, is also 

expected to be minor because existing infrastructure is regulated, because little new infrastructure is 

expected to result in the cumulative case, and because any new infrastructure will be subject to relevant 

permitting requirements. Other human activities and natural events and processes also may raise 

environmental justice issues. The cumulative consequences to environmental justice cannot be 

determined at this time. Nevertheless, when added to existing State and Federal leasing programs, the 

associated onshore infrastructure, and all of the non-OCS oil- and gas-related impacting factors, a single 

proposed CPA lease sale will make only minor contributions to the cumulative effects on environmental 

justice communities.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS

A search of various Internet information sources and trade publications (U.S. Department of Health 

and Human Services, National Institutes of Health; USEPA; USDOC, Bureau of the Census and Bureau 

of Labor Statistics; USDHS, Federal Emergency Management Agency; RestoreTheGulf.gov website; 

Deepwater Horizon Claims Center; Deepwater Horizon Oil Spill Portal; Louisiana Department of 

Environmental Quality; Mississippi Department of Environmental Quality; Alabama Department of 

Environmental Management; Florida Department of Environmental Protection; Louisiana Recovery 

Authority; and Louisiana Office of Community Development, The Greater Lafourche Port Commission, 

LA1 Coalition, Rigzone, Oil and Gas Journal and The Oil Drum), as well as recently published journal 

articles, was conducted to determine the availability of recent information on environmental justice. The 

search revealed the following new information.

The Deepwater Horizon explosion, oil spill, and response stimulated increased community outreach 

projects. For example, the Mississippi Coalition for Vietnamese-American Fisher Folks and Families 

continued its extensive outreach efforts by helping to facilitate a NRDA/Early Coastal Restoration 

training in 2012 that over 80 Vietnamese-American fisher folks attended. The Mississippi Coalition for 

Vietnamese-American Fisher Folks and Families provided qualified interpreters and translated materials 

to ease communication throughout the training. A series of Early Coastal Restoration public meetings in 

coastal counties of Mississippi were also widely attended by fisher folks who were able to participate in 

the process and present ideas for coastal restoration projects (USEPA, 2013d). 

The National Institute of Environmental Health Sciences awarded a 5-year $7.85 million grant to a 

consortium of university researchers and regional community groups that will be led by the University of 

Texas Medical Branch at Galveston. The study, known as Gulf Coast Health Alliance: Health Risks 

Related to the Macondo Spill (GC-HARMS), will be focused upon gaining an understanding of the longterm health effects attributable to the Deepwater Horizon oil spill. The GC-HARMS will examine and 

analyze human exposure and seafood contamination by “measuring the distribution of potentially 

carcinogenic PAH’s present in weathered oil” (University of Texas Medical Branch, 2013). University 

researchers will work closely with community partners using a Community-Based Participatory Research 

approach. The community groups will connect researchers with local fishermen who will be trained to do 

sampling from not only their commercial catches but also from their bycatch, which they consume and 

frequently share or barter through extended families. They will also serve as partners in the effort to 

determine how seafood is distributed in local subsistence communities. The GC-HARMS will also 

include an outreach effort to inform Gulf Coast residents of the study’s findings and other relevant 

research (University of Texas Medical Branch, 2013).

A related effort, GuLF STUDY (a national effort to determine if the Deepwater Horizon oil spill led 

to physical or mental health problems), has enrolled nearly 33,000 participants. Of the study participants, 

82 percent live in the five Gulf Coastal States and 18 percent are from other states. Minority and lowincome persons comprise 38 percent and 26 percent, respectively, of study participants. All of the 

participants either helped with the cleanup effort (74%) or were trained but did not actually help with the 

cleanup (26%) (National Institute of Environmental Health Sciences, 2013).

A U.S. Geological Survey study, Economic Vulnerability to Sea-Level Rise along the Northern U.S. 

Gulf Coast, was published in spring 2013and applied a CEVI to the northern Gulf coastal region in order 

to measure economic vulnerability to sea-level rise. 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 it revealed areas along the Gulf Coast that could most benefit from long-term 
4-208 Central Planning Area Lease Sales 235, 241, and 247 EIS

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 Gulf 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 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).

Information regarding the impacts of the Deepwater Horizon explosion, oil spill, and response 

remains incomplete. Studies regarding environmental justice concerns in light of the Deepwater Horizon

explosion, oil spill, and response are still ongoing, and it may be years before data are available. The 

NRDA process, which is ongoing, may help to inform issues relating to subsistence and other indigenous 

reliance on natural resources. However, information related to NRDA is unavailable and unobtainable at 

this time, regardless of costs. In its place, BOEM’s subject-matter experts have used credible information 

that is available and applied it using accepted socioeconomic methodologies. Although most criteria 

related to environmental justice may not be essential to a reasoned choice among alternatives, health 

impacts may be essential. Nevertheless, long-term health studies are pending and may not be available 

for use for several years or longer. BOEM will continue to seek additional information as it becomes 

available and bases the previous analysis on the best information currently available.

Incomplete or unavailable information, identified in this Supplemental EIS, 2012-2017 WPA/CPA 

Multisale EIS, and WPA 233/CPA 231 Supplemental EIS, related to environmental justice may be 

relevant to reasonably foreseeable adverse impacts on minority and low-income communities. With 

regard to the Deepwater Horizon explosion, oil spill, and response, BOEM has determined that the 

incomplete or unavailable information would not be essential to a reasoned choice among alternatives for 

the reasons stated in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS.

4.1.1.24.Species Considered due to U.S. Fish and Wildlife Service Concerns

BOEM has reexamined the analysis for species considered due to FWS concerns presented in the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional 

information presented below. The species considered are the Louisiana black bear, gopher tortoise, 

Alabama red-belly turtle, ringed map turtle, black pine snake, yellow-blotched map turtle, eastern indigo 

snake, Mississippi gopher frog, frosted flatwoods salamander, reticulated flatwoods salamander, pallid 

sturgeon, pearl darter, inflated heelsplitter, Louisiana quillwort, and telephus spurge. The conclusions for 

the following species can be found in their respective chapters: West Indian manatee (Chapter 4.1.1.12

of this Supplemental EIS and Chapter 4.2.1.12 of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS); green, hawksbill, Kemp’s ridley, leatherback, and loggerhead sea 

turtles (Chapter 4.1.1.13 of this Supplemental EIS and Chapter 4.2.1.13 of the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS); and red knot (Calidris canutus rufa), piping 

plover, whooping crane, and mountain plover (Chapter 4.1.1.16 of this Supplemental EIS and Chapter 

4.2.1.16 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS). No new 

significant information was discovered that would alter the impact conclusion for species considered due 

to FWS concerns presented in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS. The analysis and potential impacts detailed in the 2012-2017 WPA/CPA Multisale 

EIS and updated in the WPA 233/CPA 231 Supplemental EIS still apply for proposed CPA Lease Sales 

235, 241, and 247.

BOEM has only focused on species within coastal counties because those are the species that could 

potentially be impacted by oil and gas development activities, including a potential OCS spill. Because 

of the mitigations that may be implemented (Chapter 2.3.1.3), routine activities (e.g., operational 

discharges, noise, and marine debris) related to a CPA proposed action are not expected to have long-term 

adverse effects on the size and productivity of any of these species or populations (one mammal species, 

six reptile species, three amphibian species, two fish species, one bivalve species, and two plant species) 
Description of the Environment and Impact Analysis 4-209

in the Gulf of Mexico. Lethal effects could occur from ingestion of accidentally released plastic materials 

from OCS vessels and facilities. However, there have been no reports to date on such incidences.

A detailed description of species considered due to FWS concerns can be found in Chapter 4.2.1.24 of 

the 2012-2017 WPA/CPA Multisale EIS, and updated information is provided in Chapter 4.2.1.24 of the 

WPA 233/CPA 231 Supplemental EIS. A detailed explanation of the routine and accidental impactproducing factors can be found in Chapters 3.1 and 3.2 of this Supplemental EIS and Chapters 3.1 and 

3.2 of the 2012-2017 WPA/CPA Multisale EIS. The cumulative analysis in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS considers the effects of impact-producing 

factors related to past CPA lease sales, proposed CPA Lease Sales 235, 241, and 247, and reasonably 

foreseeable lease sale programs in the CPA. Cumulative impacts attributed to OCS activity co-occur with 

State oil and gas activities, other governmental and private projects and activities, and pertinent natural 

processes and events that may occur that adversely affect wetlands. 

Adverse impacts due to routine activities resulting from a CPA proposed action are possible but 

unlikely. Because of the greatly improved handling of waste and trash by industry and the annual 

awareness training required by the marine debris mitigations, it is likely that there are not as many plastics 

being added to the GOM and the devastating effects on offshore and coastal marine life are decreasing 

(USDOC, NOAA, 2011e). The routine activities of a CPA proposed action are unlikely to have 

significant adverse effects on the size and recovery of any above-mentioned species or population in the 

GOM due to the distance from shore of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements.

Adverse impacts due to accidental events are also likely to be small. Accidental blowouts, oil spills, 

and spill-response activities resulting from a CPA proposed action have the potential to impact small to 

large areas in the Gulf of Mexico, depending on the magnitude and frequency of accidents, the ability to 

respond to accidents, the location and date of accidents, and various meteorological and hydrological 

factors (including tropical storms). The incremental contribution of a CPA proposed action would not be 

likely to result in a significant incremental impact on these species within the CPA. A CPA proposed 

action would be expected to have little or no effect on these species of concern.

Cumulative activities posing the greatest potential harm to species considered due to FWS concerns

are non-OCS oil- and gas-related factors such as habitat loss and competition. These factors have 

historically proved to be of greater threat to these species of concern. 

At this time, there is no known record of a hurricane crossing the path of a large oil spill; the impacts 

of such have yet to be determined. The experience from Hurricanes Katrina and Rita in 2005 was that the 

oil released during the storms widely dispersed as far as the surge reached (USDOC, NOAA, 2010b). 

Due to their species’ reliance on terrestrial habitats to carryout their life-history functions at a 

considerable distance from the GOM, the activities of a CPA proposed action are unlikely to have 

significant adverse effects on the size and recovery of any of the above-mentioned species or populations 

in Texas, Louisiana, Mississippi, Alabama, and Florida.

As BOEM has previously noted in the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS, relevant data on the status of populations after the Deepwater Horizon explosion, oil 

spill, and response may take years to acquire and analyze, and impacts from the Deepwater Horizon

explosion, oil spill, and response may be difficult or impossible to discern from other factors. As data 

continue to be gathered and impact assessments completed, a better characterization of the full scope of 

impacts to populations in the GOM from the Deepwater Horizon explosion, oil spill, and response will be 

available. Therefore, it is not possible for BOEM to obtain this information within the timeline 

contemplated in the NEPA analysis of this Supplemental EIS, regardless of the cost or resources needed. 

In light of the incomplete or unavailable information, BOEM’s subject-matter experts have used available 

scientifically credible evidence in this analysis and applied it using accepted methods and approaches. 

Nevertheless, a complete understanding of the unavailable information is not essential to a reasoned 

choice among alternatives for this Supplemental EIS. There are existing leases in the CPA with either 

ongoing or the potential for exploration, drilling, and production activities. In addition, non-OCS energyrelated activities will continue to occur in the CPA irrespective of a CPA proposed action (i.e., habitat 

loss and competition). The potential for effects from changes to the affected environment (postDeepwater Horizon), routine activities, accidental spills, low-probability catastrophic spills), and 

cumulative effects remains whether or not an Action or No Action alternative is chosen under this 

Supplemental EIS.
4-210 Central Planning Area Lease Sales 235, 241, and 247 EIS

Summary and Conclusion 

Because of the mitigations that may be implemented, routine activities (e.g., operational discharges, 

noise, and marine debris) related to a CPA proposed action are not expected to have long-term adverse 

effects on the size and productivity of any of these species or populations in the GOM. Lethal effects 

could occur from ingestion of accidentally released plastic materials from OCS oil- and gas-related and 

non-OCS oil- and gas-related vessels and facilities. However, there have been no reports to date on such 

incidences. BOEM employs several measures (e.g., marine debris mitigations) to reduce the potential 

impacts to any animal from routine activities associated with a CPA proposed action. Accidental 

blowouts, oil spills, and spill-response activities resulting from a CPA proposed action have the potential 

to impact small to large areas in the GOM, depending on the magnitude and frequency of accidents, the 

ability to respond to accidents, the location and date of accidents, and various meteorological and 

hydrological factors (including tropical storms). The incremental contribution of a CPA proposed action 

would not be likely to result in a significant incremental impact on the above-mentioned species within 

the CPA; in comparison, non-OCS oil- and gas-related activities, such as habitat loss and competition, 

have historically proven to be a greater threat to the above-mentioned species. 

BOEM has reexamined the analysis for species considered due to FWS concerns presented in the 

2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, based on the additional 

information presented above. No new significant information was discovered that would alter the impact 

conclusion for species considered due to FWS concerns presented in the 2012-2017 WPA/CPA Multisale 

EIS and WPA 233/CPA 231 Supplemental EIS because of the available scientifically credible evidence in 

this analysis and based upon accepted scientific methods and approaches. The analysis and potential 

impacts detailed in the 2012-2017 WPA/CPA Multisale EIS and updated in the WPA 233/CPA 231 

Supplemental EIS still apply for proposed CPA Lease Sales 235, 241, and 247. 

There is a long-standing and well-developed OCS Program of more than 50 years within the CPA, 

and there are no data to suggest that activities from the preexisting OCS Program are significantly 

impacting the above-mentioned species populations; therefore, a CPA proposed action would be expected 

to have little or no effect on the above-mentioned species. 

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS 

and WPA 233/CPA 231 Supplemental EIS 

A search of Internet information sources (FWS’s websites), as well as recently published journal 

articles was conducted to determine the availability of recent information on species considered due to 

FWS concerns. The search revealed no new information pertinent to this Supplemental EIS. 

These one mammal species, six reptile species, three amphibian species, two fish species, one bivalve 

species, and two plant species within the CPA were not affected to any discernible degree by the 

Deepwater Horizon explosion, oil spill, and response, based on the best available information and the 

distance from the Macondo well. As identified in the resource analyses in this Supplemental EIS and 

2012-2017 WPA/CPA Multisale EIS, and in the updated information provided in the WPA 233/CPA 231 

Supplemental EIS, incomplete or unavailable information regarding these one mammal species, six reptile 

species, three amphibian species, two fish species, one bivalve species, and two plant species in the CPA 

are not relevant to reasonably foreseeable significant adverse effects. BOEM has determined that the 

information is not essential to a reasoned choice among alternatives. 

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

Biologically Sensitive Topographic Features 

Description of the Alternative 

Alternative B differs from Alternative A (the proposed action) by not offering blocks that are possibly 

affected by the proposed Topographic Features Stipulation (Chapter 2.3.1.3.1 of this Supplemental EIS 

and Chapter 2.4.1.3.1 of the 2012-2017 WPA/CPA Multisale EIS). All of the assumptions (including the 

seven other potential mitigating measures) and estimates are the same as for the proposed action 

(Alternative A). A description of Alternative A is presented in Chapter 2.3.1.1. 
Description of the Environment and Impact Analysis 4-211

Effects of the Alternative 

The following analyses are based on the scenario for a CPA proposed action (Alternative A). The 

scenario provides assumptions and estimates on the amounts, locations, and timing for OCS exploration, 

development, and production operations and facilities, both offshore and onshore. These are estimates 

only and not predictions of what would happen as a result of holding proposed CPA Lease Sales 235, 

241, and 247. A detailed discussion of the scenario and related impact-producing factors is presented in

Chapter 3.1 of this Supplemental EIS and in Chapter 3.1 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 3.1 of the WPA 233/CPA 231 Supplemental EIS. 

The analyses of impacts to the various resources under Alternative B are very similar to those for 

Alternative A. The reader should refer to the appropriate discussions under Alternative A for additional 

and more detailed information regarding impact-producing factors and their expected effects on the 

various resources. Impacts under Alternative B are expected to be the same as a CPA proposed action 

(Chapter 4.1.1) for the following resources:

— Air Quality

— Water Quality

— Coastal Barrier Beaches and Associated 

Dunes

— Wetlands

— Seagrass Communities

— Live Bottoms (Pinnacle Trend and 

Low Relief) 

— Sargassum Communities

— Chemosynthetic and Nonchemosynthetic 

Deepwater Benthic Communities

— Soft Bottom Benthic Communities

— Marine Mammals

— Sea Turtles

— Diamondback Terrapins

— Alabama, Choctawhatchee, St. Andrew 

and Perdido Key Beach Mice

— Coastal and Marine Birds

— Gulf Sturgeon

— Fish Resources and Essential Fish 

Habitat

— Commercial Fisheries

— Recreational Fishing

— Recreational Resources

— Archaeological Resources

— Human Resources and Land Use

The impacts to some Gulf of Mexico resources under Alternative B would be slightly different from 

the impacts expected under a CPA proposed action (Alternative A). These impacts are described below.

Impacts on Topographic Features

The sources and severity in impacts associated with this alternative are those lease sale-related 

activities discussed for a CPA proposed action. The potential impact-producing factors to the topographic 

features of the CPA are anchoring and structure emplacement, effluent discharge, blowouts, oil spills, and 

structure removal. A more detailed discussion of these potential impact-producing factors and the 

appropriate mitigating measures are presented in Chapter 2.3.1.3.1 of this Supplemental EIS and Chapter 

2.4.1.3.1 of the 2012-2017 WPA/CPA Multisale EIS.

Impacts of Routine and Accidental Events

Of the 16 topographic features in the CPA, 15 are located within water depths less than 200 m 

(656 ft). Geyer Bank is located in water depths of 190-210 m (623-689 ft). These features occupy a very 

small portion of the entire area. Of the potential impact-producing factors that may affect the topographic 

features, anchoring, structure emplacement, and structure removal would be eliminated by the adoption of 

this alternative. Effluent discharge and blowouts would not be a threat to the topographic features 

because blocks near enough to the banks for these events to have an impact on the biota of the banks 

would have been excluded from leasing under this alternative. Thus, the only impact-producing factor 

remaining from operations in blocks included in this alternative (i.e., those blocks not excluded by this 

alternative) is an oil spill. The potential impacts from oil spills are summarized below and are discussed 

further in Chapter 3.2.1 of this Supplemental EIS and in Chapter 3.2.1 of the 2012-2017 WPA/CPA 

Multisale EIS and the WPA 233/CPA 231 Supplemental EIS. 

A subsurface spill would have no effect on a biologically sensitive feature unless the oil or its 

dissolved components comes into direct contact with the habitat. Oil from a subsurface spill is expected 

to rise to the sea surface, based on the specific gravity of Gulf of Mexico oil. An exception to this could 
4-212 Central Planning Area Lease Sales 235, 241, and 247 EIS

occur if oil is released at the seafloor under high pressure, having the effect of atomizing the oil into 

micro-droplets that have very little buoyancy. Under these conditions, a subsea oil plume could form and 

travel laterally with the prevailing currents. This can also happen if chemical dispersants are used 

underwater, forming a plume. If a subsea oil plume does form, the oil is expected to be swept clear of the 

banks because prevailing currents travel around the banks rather than over them (Rezak et al., 1983). As 

the oil travels in the water column, it will become diluted from its original concentration. Transient 

concentrations of oil below 20 ppm are not expected to result in lasting harm to a coral reef (Shigenaka, 

2001). The fact that the topographic features are widely dispersed in the CPA, combined with the random 

nature of spill events, would serve to limit the likelihood of a spill occurring near a topographic feature. 

In addition, the exclusion of blocks adjacent to topographic features from a proposed CPA lease sale 

would further distance potential spills from the habitat. Chapter 4.2.1.7 of the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS discusses the risk of spills interacting with 

topographic features in more detail. The currents that move around the banks would likely steer any 

spilled oil around the banks rather than directly upon them, lessening impact severity. In the unlikely 

event that oil from a subsurface spill would reach the biota of a topographic feature, the effects would be 

primarily sublethal for most of the adult sessile biota. Lethal effects would probably be limited to a few 

coral colonies (CSA, 1992 and 1994). If oil from a subsurface spill contacted a coral-covered area, the 

areal extent of coral mortality would be limited, but long-lasting sublethal effects may be incurred by 

organisms surviving the initial effects of a spill (Jackson et al., 1989). Stress resulting from the oiling of 

reef coral colonies could affect their resilience to natural disturbances (e.g., elevated water temperature 

and diseases) and may hamper their ability to reproduce. A complete recovery of such an affected area 

could take in excess of 10 years. 

Cumulative Impacts

With the exception of the topographic features, the cumulative impacts of Alternative B on the 

environmental and socioeconomic resources of the CPA would be identical to Alternative A. The 

incremental contribution of a CPA proposed action to the cumulative impacts on topographic features is 

expected to be slight, and negative impacts should be restricted by the implementation of the Topographic 

Features Stipulation and site-specific mitigations, the depths of the features, and water currents in the 

topographic feature area.

Summary and Conclusion

Alternative B, if adopted, would prevent any oil and gas activity whatsoever in the blocks containing 

topographic features and their surrounding protective zones ; thus, it would eliminate any potential direct 

impacts to the biota of those blocks from routine oil and gas activities within the blocks. In the unlikely 

event that oil from a subsurface spill contacts the biota of a topographic feature, the effects would be 

localized and primarily sublethal for most of the adult sessile biota. Some lethal effects would probably 

occur upon oil contact to coral colonies.

Environmental impacts of Alternative B would be almost indistinguishable from Alternative A with 

the Topographic Features Stipulation in place. There would be an economic impact to the extent that 

economic returns from the excluded lease blocks would not be realized.

4.1.3. Alternative C—No Action

Description of the Alternative

Alternative C is the cancellation of a proposed CPA lease sale. If this alternative is chosen, the 

opportunity for development of the estimated 0.460-0.894 BBO and 1.939-3.903 Tcf of gas that could 

have resulted from a proposed CPA lease sale would be precluded during the current 2012-2017 FiveYear Program, but it could again be contemplated as part of a future Five-Year Program. The No Action 

alternative encompasses the same potential impacts as a decision to delay a proposed CPA lease sale to a 

later scheduled lease sale under the Five-Year Program, when another decision on whether to hold that 

future lease sale is made. Delay of a proposed CPA lease sale was not considered as a separate alternative 

from Alternative C because the potential impacts are the same, namely that most impacts related to 

Alternative A would not occur as described below. Any potential environmental impacts resulting from a 
Description of the Environment and Impact Analysis 4-213

proposed CPA lease sale would not occur or would be postponed to a future lease sale decision. This 

alternative is also analyzed in the EIS for the 2012-2017 Five-Year Program on a nationwide 

programmatic level.

Effects of the Alternative

This Agency published a report that examined previous exploration and development activity 

scenarios (USDOI, MMS, 2007). This Agency compared forecasted activity with the actual activity from 

14 WPA and 14 CPA lease sales. The report shows that many lease sales contribute to the present level 

of OCS activity, and any single lease sale accounts for only a small percentage of the total OCS activities. 

In 2006, leases from 92 different sales contributed to Gulf of Mexico production, while an average CPA 

lease sales contributed to 2 percent of oil production and 2 percent of gas production in the CPA. In 

2006, leases from 15 different sales contributed to the installation of production structures in the Gulf of 

Mexico, while an average CPA lease sale, for example, contributed to 6 percent of the installation of 

production structures in the CPA. In 2006, leases from 70 different sales contributed to wells drilled in 

the Gulf of Mexico, while an average CPA lease sale contributed to 4 percent of the wells drilled in the 

CPA.

As in the past, a proposed CPA lease sale would contribute to maintaining the present level of OCS 

activity in the Gulf of Mexico. Exploration and development activity, including service-vessel trips, 

helicopter trips, and construction that would result from a proposed CPA lease sale would replace activity 

resulting from existing leases that have reached, or are near the end of, their economic life.

Environmental Impacts

If a proposed CPA lease sale would be cancelled, the resulting development of oil and gas would 

most likely be postponed to a future sale; therefore, the overall level of OCS activity in the CPA would 

only be reduced by a small percentage, if any. Therefore, the cancellation of a proposed CPA lease sale 

would not significantly change the environmental impacts of overall OCS activity in the long term. The 

environmental impacts expected to result from a CPA proposed action, which are described above, would 

not occur in the short term, but they would likely be postponed to any future lease sale.

Economic Impacts 

Although environmental impacts may be reduced or postponed by cancelling a proposed CPA lease 

sale, the economic impacts of cancelling the scheduled lease sale should be given consideration. Chapter 

4.2.1.23.3.2 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.23.3 of the WPA 233/CPA 231 

Supplemental EIS discusses the potential economic impacts of a CPA proposed action. In the event that a 

proposed CPA lease sale is cancelled or postponed, there may be impacts to employment along the Gulf 

Coast, but these are not expected to be significant (e.g., less than 1% of total employment) or long term 

given the existing OCS infrastructure. 

Federal, State, and local governments would also have to forgo the revenue that would have been 

received from a proposed CPA lease sale. There could be minor impacts on global energy prices from 

cancelling the proposed CPA lease sale, along with minor changes in energy consumption patterns that 

would result from these price changes. 

Other factors may minimize or exacerbate the economic impacts of cancelling a proposed CPA lease 

sale. For example, the longer-term economic impacts of cancelling the CPA proposed lease sale could be 

minimized if they were offset by a larger lease sale at a later date. The economic impacts may be 

exacerbated if additional lease sales are cancelled. The OCS industry is dependent on high capital 

investment costs and there may be long lags between the lease sale and the majority of production 

activities. Therefore, firms’ investment and spending decisions are dependent on their confidence that the 

OCS Program will be maintained in the future. In addition, while firms in the OCS industry are generally 

likely to be able to weather the cancellation of a single lease sale, the cancellation of multiple lease sales 

could lead to broader damage to firms and workers in the industry or decisions to operate in areas other 

than the Gulf. These economic impacts would be particularly damaging to the coastal counties in Texas 

and Louisiana for which the OCS industry as a whole is an important component of their economies.

From a programmatic perspective, cancellation of a Five-Year Program of lease sales in the Gulf of 

Mexico would have much greater effects in terms of economic impacts, energy strategy, and 
4-214 Central Planning Area Lease Sales 235, 241, and 247 EIS

environmental impacts. For a more detailed discussion of the effects of the cancellation of a Five-Year 

Program of lease sales in the Gulf of Mexico, refer to Appendix G of the 2012-2017 WPA/CPA Multisale 

EIS.

Summary and Conclusion

Cancelling a proposed CPA lease sale would eliminate the effects described for Alternative A 

(Chapter 4.1.1). Other sources of energy would substitute for the lost production. Principal substitutes 

would be additional imports, conservation, additional domestic production, and switching to other fuels. 

These alternatives, except conservation, have significant negative environmental impacts of their own. 

For example, tankering of fuels from alternate sources over longer distances would also have significant 

potential negative impacts, including through the increased risk of spills. 

4.2. UNAVOIDABLE ADVERSE IMPACTS OF THE PROPOSED ACTIONS

Unavoidable adverse impacts associated with a CPA proposed action are expected to be primarily 

short term and localized in nature and are summarized below. Adverse impacts from low-probability 

catastrophic events could be of longer duration and extend beyond the local area. All OCS oil- and gasrelated activities involve temporary and exclusive use of relatively small areas of the OCS over the 

lifetimes of specific projects. Lifetimes for these activities can be days, as in the case of seismic surveys; 

or decades, as in the case of a production structure or platform. No activities in the OCS Program involve 

the permanent or temporary use or “taking” of large areas of the OCS on a semicontinuous basis. 

Cumulatively, however, a multitude of individual projects results in a major use of OCS space.

Sensitive Coastal Habitats: If an oil spill contacts beaches or barrier islands, the removal of beach 

sand during cleanup activities could result in adverse impacts if the sand is not replaced. In addition, a 

beach could experience several years of tarballs washing ashore over time, causing an aesthetic impact. 

Sand borrowing on the OCS for coastal restorations involves the taking of a quantity of sand from the 

OCS and depositing it onshore, essentially moving small products of the deltaic system to another 

location. If sand is left where it is, it would eventually be lost to the deltaic system by redeposition or 

burial by younger sediments; if transported onshore, it would be lost to burial and submergence caused by 

subsidence and sea-level rise.

If an oil spill contacts coastal wetlands, adverse impacts could be high in localized areas. In more 

heavily oiled areas, wetland vegetation could experience suppressed productivity for several years; in 

more lightly oiled areas, wetland vegetation could experience die-back for one season. Epibionts on 

wetland vegetation and grasses in the tidal zone could be killed, and the productivity of tidal marshes for 

the vertebrates and invertebrates that use them to spawn and develop could be impaired. Much of the 

wetland vegetation would recover over time, but some wetland areas could be converted to open water. 

Some unavoidable impacts could occur during pipeline and other related coastal construction, but 

regulations are in place to avoid and minimize these impacts to the maximum extent practicable. 

Unavoidable impacts resulting from dredging, wake erosion, and other secondary impacts related to 

channel use and maintenance would occur as a result of a CPA proposed action.

Sensitive Coastal and Offshore Biological Habitats: Unavoidable adverse impacts would take place 

if an oil spill occurred and contacted sensitive coastal and offshore biological habitats, such as Sargassum

at the surface; fish, turtles, and marine mammals in the water column; or benthic habitats on the bottom. 

There could be some adverse impacts on organisms contacted by oil, dispersant chemicals, or emulsions 

of dispersed oil droplets and dispersant chemicals that, at this time, are not completely understood, 

particularly in subsurface environments.

Water Quality: 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. The 

discharge of treated sewage from manned rigs and platforms would increase the levels of suspended 

solids, nutrients, chlorine, and biochemical oxygen demand in a small area near the discharge point for a 

short period of time. Accidental spills from platforms and the discharge of produced waters could result 

in increases of hydrocarbon levels and trace metal concentrations in the water column in the vicinity of 
Description of the Environment and Impact Analysis 4-215

the platforms. Spilled oil from a tanker collision would affect the water surface in combination with 

dispersant chemicals used during spill response. A subsurface blowout would subject the surface, water 

column, and near-bottom environment to spilled oil and gas released from solution, dispersant chemicals, 

or emulsions of dispersed oil droplets and dispersant chemicals.

Unavoidable impacts to onshore water quality would occur as a result of chronic point- and nonpointsource discharges such as runoff and effluent discharges from existing onshore infrastructure used in 

support of lease sale activities. Vessel traffic contributes to the degradation of water quality by chronic 

low-quantity oil leakage, treated sanitary and domestic waste, bilge water, and contaminants known to 

exist in ship paints. Regulatory requirements of the State and Federal water authorities and some local 

jurisdictions would be applicable to point-source discharges from support facilities such as refineries and 

marine terminals.

Air Quality: Unavoidable short-term impacts on air quality could occur after large oil spills and 

blowouts because of evaporation and volatilization of the lighter components of crude oil, combustion 

from surface burning, and aerial spraying of dispersant chemicals. Short-term effects from spill events 

are uncontrollable and are likely to be aggravated or mitigated by the time of year the spills take place. 

Mitigation of long-term effects from offshore engine combustion during routine operations would be 

accomplished through existing regulations and the development of new control emission 

technology.Threatened and Endangered Species: Because the proposed CPA lease sales do not in and of 

themselves make any irreversible or irretrievable commitment of resources that would foreclose the 

development or implementation of any reasonable and prudent measures to comply with the Endangered 

Species Act, BOEM may proceed with publication of this Supplemental EIS and finalize a decision 

among these alternatives even if consultation is not complete, consistent with section 7(d) of the ESA 

(also refer to Chapter 5.7). Irreversible loss of individuals that are ESA-listed species may occur after a 

large oil spill from the acute impact of being oiled or the chronic impact of oil having eliminated, 

reduced, or rendered suboptimal the food species upon which they were dependent.

Nonendangered and Nonthreatened Marine Mammals: Unavoidable adverse impacts to 

nonendangered and nonthreatened marine mammals would be those that also affect endangered and 

threatened marine mammal species. Routine operation impacts (such as seismic surveys, water quality

and habitat degradation, helicopter disturbance, vessel collision, and discarded trash and debris) would be 

negligible or minor to a population, but they could be lethal to individuals as in the case of a vessel 

collision. A large oil spill would temporarily degrade habitat if spilled oil, dispersant chemicals, or 

emulsions of dispersed oil droplets and dispersant chemicals contact free-ranging pods or spawning 

grounds.

Coastal and Marine Birds: Unavoidable adverse impacts from routine operations on coastal birds 

could result from helicopter and OCS service-vessel traffic, facility lighting, and floating trash and debris. 

Marine birds could be affected by noise, platform lighting, aircraft disturbances, and trash and debris 

associated with offshore activities. Cross-Gulf migrating species could be affected by lighted platforms, 

helicopter and vessel traffic, and floating trash and debris. If a large oil spill occurs and contacts coastal 

or marine bird habitats, some birds could experience lethal and sublethal impacts from oiling, and birds 

feeding or resting in the water could be oiled and die. Coastal birds coming into contact with oil may 

migrate more deeply into marsh habitats, out of reach from spill responders seeking to count them or 

collect them for rehabilitation. Oil spills and oil-spill cleanup activities could also affect the food species 

for coastal, marine, and migratory bird species. Depending on the time of year, large oil spills could 

decrease the nesting success of species that concentrate nests in coastal environments due to direct effects 

of the spill and also disruption from oil-spill cleanup activities.

Fish Resources, Commercial Fisheries, and Recreational Fishing: Unavoidable adverse impacts 

from routine operations are loss of open ocean or bottom areas desired for fishing by the presence or 

construction of OCS oil- and gas-related facilities and pipelines. Loss of gear could occur from bottom 

obstructions around platforms and subsea production systems. Routine discharges from vessels and 

platforms are minor given the available area for fish habitat. If a large oil spill occurs, the oil, dispersant

chemicals, or emulsions of oil droplets and dispersant chemicals could temporarily displace mobile fish 

species on a population or local scale. There could also be impacts on prey and sublethal effects on fish. 

It is unlikely that fishermen would want, or be permitted, to harvest fish in the area of an oil spill, as 

spilled oil could coat or contaminate commercial fish species, rendering them unmarketable.

Recreational Beaches: Unavoidable adverse impacts from routine operations may result in the 

accidental loss overboard of some floatable debris that may eventually come ashore on frequented 
4-216 Central Planning Area Lease Sales 235, 241, and 247 EIS

recreational beaches. A large oil spill could make landfall on recreational beaches, leading to local or 

regional economic losses and stigma effects, causing potential users to avoid the area after acute impacts 

have been removed. Some recreational beaches become temporarily soiled by weathered crude oil, and 

tarballs may come ashore long after stranded oil has been cleaned from shoreline areas.

Economic Activity: Net economic, political, and social benefits accrue from the production of 

hydrocarbon resources. Once these benefits become routine, unavoidable adverse impacts from routine 

operations follow trends in supply and demand based on the commodity prices for oil, gas, and refined 

hydrocarbon products. Declines in oil and gas prices can lead to activity ramp downs by operators until 

prices rise. A large oil spill would cause temporary increases in economic activity associated with spillresponse activity. An increase in economic activity from the response to a large spill could be offset by 

temporary work stoppages that are associated with spill-cause investigations and would involve a transfer 

or displacement of demand to different skill sets. An oil spill could also negatively impact industries such 

as tourism and fishing. 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 dropoff of activity as operators adjust to new expectations or use the opportunity to move resources to other 

basins where they have interests.

Archaeological Resources: Unavoidable adverse impacts from routine operations could lead to the 

loss of unique or significant archaeological information if unrecognized at the time an area is disturbed. 

Required archaeological surveys significantly reduce the potential for this loss by identifying potential 

archaeological sites prior to an interaction occurring, thereby making avoidance or mitigation of impacts 

possible. A large oil spill that makes landfall on or near protected archaeological landmarks could cause 

temporary aesthetic or cosmetic impacts until the oil is cleaned or degrades.

4.3. IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES

Irreversible or irretrievable commitment of resources refers to impacts or losses to resources that 

cannot be reversed or recovered. Examples are when a species becomes extinct or when wetlands are 

permanently converted to open water. In either case, the loss is permanent.

Wetlands: An irreversible or irretrievable loss of wetlands and associated biological resources could 

occur if wetlands are permanently lost because of impacts caused by dredging and construction activities 

that displace existing wetlands or from oil spills severe enough to cause permanent die-back of vegetation 

and conversion to open water. Construction and emplacement of onshore pipelines in coastal wetlands 

displace coastal wetlands in disturbed areas that are then subject to indirect impacts like saltwater 

intrusion or erosion of the marsh soils along navigation channels and canals. Ongoing natural and 

anthropogenic processes in the coastal zone, only one of which is OCS oil- and gas-related activity, can 

result in direct and indirect loss of wetlands. Natural losses as a consequence of the coastal area 

becoming hydrologically isolated from the Mississippi River that built it, sea-level rise, and subsidence of 

the delta platform in the absence of new sediment added to the delta plain appear to be much more 

dominant processes impacting coastal wetlands.

Sensitive Nearshore and Offshore Biological Resources: An irreversible loss or degradation of 

ecological habitat caused by cumulative activity tends to be incremental over the short term. Irretrievable 

loss may not occur unless or until a critical threshold is reached. It can be difficult or impossible to 

identify when that threshold is, or would be, reached. Oil spills and chronic low-level pollution can injure 

and kill organisms at virtually all trophic levels. Mortality of individual organisms can be expected to 

occur, and possibly a reduction or even elimination of a few small or isolated populations. The proposed 

biological stipulations, however, are expected to eliminate most of these risks.

Threatened and Endangered Species: Irreversible loss of individuals that are protected species may 

occur after a large oil spill from the acute impact of being oiled or the chronic impact of oil having 

eliminated, reduced, or rendered suboptimal the food species upon which they were dependent.

Fish Resources and Commercial Fisheries: Irreversible loss of fish and coral resources, including 

commercial and recreational species, are caused by structure removal using explosives. Fish in proximity 

to an underwater explosion can be killed. Without the structure to serve as habitat area, sessile, attached 

invertebrates and the fish that live among them are absent. Removing structures eliminates these special 

and local habitats and the organisms living there, including such valuable species as red snapper. 
Description of the Environment and Impact Analysis 4-217

Continued structure removal, regardless of the technique used, would reduce the net benefits to 

commercial fishing due to the presence of these structures.

Recreational Beaches: Impacts on recreational beaches from a large oil spill may, at the time, seem 

irreversible, but the impacts are 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: Irreversible loss of a prehistoric or historic archaeological resource can 

occur if bottom-disturbing activity takes place without the surveys, where required, to demonstrate its 

absence before work proceeds. A resource can be completely destroyed, severely damaged, or the 

scientific context badly impaired by well drilling, subsea completions, and platform and pipeline 

installation, or sand borrowing.

Oil and Gas Development: Leasing and subsequent development and extraction of hydrocarbons as a 

result of a CPA 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 CPA proposed action is presented in Table 3-1. 

Loss of Human and Animal Life: The OCS oil and gas exploration, development, production, and 

transportation are carried out under comprehensive, state-of-the-art, enforced regulatory procedures 

designed to ensure public and work place safety and environmental protection. Nevertheless, some loss 

of human and animal life may be inevitable from unpredictable and unexpected acts of man and nature 

(i.e., unavoidable accidents, accidents caused by human negligence or misinterpretation, human error, 

willful noncompliance, and adverse weather conditions). Some normal and required operations, such as 

structure removal, can kill sea life in proximity to explosive charges or by removal of the structure that 

served as the framework for invertebrates living on it and the fish that lived with it.

4.4. RELATIONSHIP BETWEEN THE SHORT-TERM USE OF MAN’S ENVIRONMENT 

AND THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY

The short-term effects on various components of the environment in the vicinity of a CPA proposed 

action are related to long-term effects and the maintenance and enhancement of long-term productivity.

Short-Term Use

Short-term refers to the total duration of oil and gas exploration and production activities. Extraction 

and consumption of offshore oil and natural gas is a short-term benefit. Discovering and producing 

domestic oil and gas now reduces the Nation’s dependency on foreign imports. Depleting a 

nonrenewable resource now removes these domestic resources from being available for future use. The 

production of offshore oil and natural gas as a result of a CPA 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 

0.460-0.894 BBO and 1.939-3.903 Tcf of gas from a typical CPA proposed action. The cumulative 

impacts scenario in this Supplemental EIS extends approximately from 2012 to 2051. The 40-year time 

period is used because it is the approximate longest life span of activities conducted on an individual 

lease. The 40 years following a proposed CPA lease sale is the period of time during which the activities 

and impacting factors that follow as a consequence of a proposed CPA lease sale would be influencing 

the environment.

The specific impacts of a CPA 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 CPA 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 
4-218 Central Planning Area Lease Sales 235, 241, and 247 EIS

of the habitat for encrusting invertebrates and fish living among them. Many of the effects on physical, 

biological, and socioeconomic resources discussed in Chapter 4.1 are considered to be short term (being 

greatest during the construction, exploration, and early production phases). These impacts would be 

further reduced by the mitigating measures discussed in Chapter 2.2.2. 

The OCS development off Texas, Louisiana, Mississippi, and Alabama 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. A 

CPA proposed action could increase these incidental benefits of offshore development. Offshore fishing 

and diving has gradually increased in the past three decades, with offshore structures and platforms 

becoming the focus of much of that activity. As mineral resources become depleted, platform removals 

would occur and may result in a decline in these activities.

The short-term exploitation of hydrocarbons for the OCS Program in the Gulf of Mexico may have 

long-term impacts on biologically sensitive coastal and offshore resources and areas if a large oil spill

occurs. A spill and spill-response activity could temporarily interfere with commercial and recreational 

fishing, beach use, and tourism in the area where the spill makes landfall and in a wider area based on 

stigma effects. The proposed leasing may also result in onshore development and population increases 

that could cause very short-term adverse impacts to local community infrastructure, particularly in areas

of low population and minimal existing industrial infrastructure (Chapter 4.2.1.23.1 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS). 

Relationship to Long-Term Productivity

Long-term refers to an indefinite period beyond the termination of oil and gas production. Over a 

period of time after peak oil production has occurred in the Gulf of Mexico, a gradual easing of the 

specific impacts caused by oil and gas exploration and production would occur as the productive 

reservoirs in the Gulf have been discovered and produced, and have become depleted. The Oil Drum 

(2009) showed a graphic demonstrating that peak oil production in the Gulf occurred in June 2002 at 

1.73 MMbbl/day. Whether or not this date is correct can only be known in hindsight and only after a 

period of years while production continues. At this time, however, the trend is fairly convincing (The Oil 

Drum, 2009). There is disagreement on what future production trends may be in the Gulf of Mexico after 

several operators, BP among them, announced discoveries over the last 5 years (Oil and Gas Journal, 

2009) in the Lower Tertiary in ultra-deepwater (>5,000 ft; 1,524 m) with large projected reserves. These 

claims are as yet unproven and there are questions as to the difficulties that may be encountered 

producing these prospects because of their geologic age; burial depth and high-temperature, high-pressure 

in-situ conditions; lateral continuity of reservoirs; and the challenges of producing from ultra-deepwater 

water depths.

The Gulf of Mexico’s large marine ecosystem is considered a Class II, moderately productive 

ecosystem (mean phytoplankton primary production 150-300 gChlorophyll a/m2

-yr [The Encyclopedia of 

Earth, 2008]) based on Sea-viewing Wide Field-of-view Sensor (SeaWiFS) global primary productivity 

estimates (USDOC, NASA, 2003). After the completion of oil and gas production, a gradual ramp-down 

to economic conditions without oil and gas activity would be experienced, while the marine environment 

is generally expected to remain at or return to its normal long-term productivity levels that, in recent 

years, has been described as stressed (The Encyclopedia of Earth, 2008). The Gulf of Mexico’s large 

marine ecosystem shows signs of ecosystem stress in bays, estuaries, and coastal regions (Birkett and 

Rapport, 1999). There is shoreline alteration, pollutant discharge, oil and gas development, and nutrient 

loading. The overall condition for the U.S. section of this large marine ecosystem, according to USEPA’s 

seven primary indicators (Jackson et al., 2000), is good dissolved oxygen, fair water quality, poor coastal 

wetlands, poor eutrophic condition, and poor sediment, benthos, and fish tissue (The Encyclopedia of 

Earth, 2008).

To help sustain the long-term productivity of the Gulf of Mexico ecosystem, the OCS Program 

provides structures to use as site-specific artificial reefs and fish-attracting devices for the benefit of 

commercial and recreational fishermen and to sport divers and spear fishers. Additionally, the OCS 

Program continues to improve the knowledge and mitigation practices used in offshore development. 

Approximately 10 percent of the oil and gas structures removed from the OCS are eventually used for 

State artificial reef programs.
CHAPTER 5 

CONSULTATION AND COORDINATION

Consultation and Coordination 5-3 

5. CONSULTATION AND COORDINATION

5.1. DEVELOPMENT OF THE PROPOSED ACTIONS

This Supplemental EIS addresses three proposed Federal OCS oil and gas lease sales, i.e., Lease Sales

235, 241, and 247 in the CPA of the Gulf of Mexico OCS, as scheduled in the Five-Year Program 

(USDOI, BOEM, 2012a). BOEM conducted early coordination with appropriate Federal and State 

agencies and other concerned parties to discuss and coordinate the prelease process for the proposed CPA 

lease sales and this Supplemental EIS. Key agencies and organizations included the National Oceanic 

and Atmospheric Administration (NOAA), NOAA’s National Marine Fisheries Service (NMFS), 

U.S. Fish and Wildlife Service (FWS), U.S. Coast Guard (USCG), U.S. Department of Defense (DOD), 

U.S. Environmental Protection Agency (USEPA), State governors’ offices, and industry groups.

5.2. NOTICE OF INTENT TO PREPARE A SUPPLEMENTAL EIS AND CALL FOR 

INFORMATION

On August 23, 2013, the Notice of Intent to Prepare a Supplemental EIS (NOI) for the proposed CPA 

lease sales was published in the Federal Register (2013b). Additional public notices were distributed via 

the U.S. Postal Service, and the Internet. A 30-day comment period was provided; it closed on 

September 23, 2013. Federal, State, and local governments, along with other interested parties, were 

invited to send written comments to the Gulf of Mexico OCS Region on the scope of the Supplemental 

EIS. BOEM received eleven comment letters in response to the NOI. These comments are summarized 

below in Chapter 5.3.1. Public scoping meetings were held in Louisiana, Mississippi, and Alabama on 

the following dates and at the times and locations indicated below:

Monday, September 9, 2013

6:30 p.m. CDT 

Courtyard by Marriott

 Gulfport Beachfront MS Hotel

1600 East Beach Boulevard

Gulfport, Mississippi 39501

5 registered attendees

2 speakers

Tuesday, September 10, 2013

6:30 p.m. CDT 

Hilton Garden Inn Mobile West

828 West I-65 Service Road South

Mobile, Alabama 36609

2 registered attendees

0 speakers

Wednesday, September 12, 2012

1:00 p.m. CDT 

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

1201 Elmwood Park Boulevard

New Orleans, Louisiana 70123

1 registered attendee

0 speakers

On July 9, 2012, the Call for Information (Call) for proposed CPA Lease Sales 231, 235, 241, and 

247 was published in the Federal Register (2012c). The comment period closed on August 8, 2012. This 

Agency received two comment letters in response to the Call. These comments are summarized below in 

Chapter 5.3.2. 

5.3. DEVELOPMENT OF THE DRAFT SUPPLEMENTAL EIS

Scoping for the Draft Supplemental EIS was conducted in accordance with CEQ regulations 

implementing NEPA. Scoping provides those with an interest in the OCS Program an opportunity to 

provide comments on the proposed actions. In addition, scoping provides BOEM an opportunity to 

update the Gulf of Mexico OCS Region’s environmental and socioeconomic information base.
5-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

5.3.1. Summary of Scoping Comments

Eleven comments were received in response to the NOI from Federal agencies, State government, 

interested groups, industry, and the general public on the scope of the Supplemental EIS, significant 

issues that should be addressed, alternatives that should be considered, and mitigating measures. All 

scoping comments received, which were appropriate for a lease sale NEPA document, were considered in 

the preparation of the Draft Supplemental EIS. Comments received included the following:

• BOEM must oversee oil and gas development in a way that protects Alabama from 

future incidents; BOEM must constantly examine their practices and procedures to 

improve their ability to provide safe offshore operations; Alabama understands the 

importance of the oil and gas industry to the Nation and supports its safe production

offshore provided those developments comply with applicable Alabama laws, rules, 

and regulations, and is in compliance with Alabama’s Coastal Zone Management

Plan; Alabama asks for protection of live bottom, pinnacle reefs, chemosynthetic 

communities, and other sensitive areas (including archaeological sites); Alabama 

opposes leases within 15 mi (24 km) south of Baldwin County; and Alabama requests 

just and equitable revenue sharing under the Gulf of Mexico Energy Security Act and 

calls for new legislation for additional revenue sharing;

• the Gulf is contaminated enough so leave it alone;

• no more drilling; opposes lease sales; BOEM cannot monitor the oil industry; oil 

companies do not care about regulations and will continue to destroy our lands;

• there is a way to produce oil and gas in the Gulf near the barrier islands without 

permanent derricks and platforms; use dredge material to rebuild barrier islands that 

can hold, protect, and hide wells; and use horizontal drilling techniques; 

• BOEM must focus EIS analyses on currently available, new information and should 

not speculate on future results from ongoing studies. BOEM should also take into 

consideration the new safety and regulatory improvements since the Deepwater

Horizon explosion, oil spill, and response as a part of the new information analyzed. 

Suggest that this Supplemental EIS be designed specifically for use as a tiering 

document for future environmental reviews. Data from the best-available, peerreviewed scientific literature should be the basis of environmental analyses, and not 

speculation;

• BOEM and BSEE must evaluate regulatory oversight, safety procedures, and new 

technologies in light of recent accidents around the world to ensure safe oil and gas 

operations on the United States’ OCS; 

• “. . . BOEM should suspend preparation of the SEIS and establish a fundamental 

revision to the planning, oversight, and approval process for offshore drilling 

activities. It should also allow for site assessment and permitting activities for 

renewable energy in the Gulf of Mexico. . . . BOEM must fully consider how the 

impacts of the DWH Spill changed the ecological baselines of the Gulf of Mexico, 

regardless of the amount of time it takes to attain this information. . . . BOEM must 

not approve any new activities in the CPA until these actions are complete”; 

• the USEPA provided guidance on topics including the following: statement of 

purpose and need; alternatives analysis; affected environment; environmental 

consequences; Marine Protection, Research and Sanctuaries Act; oil management and 

spill analysis; discharge of dredged or fill materials; water quality; biological 

resources, habitat, and wildlife; air quality; greenhouse gases; climate change; 

hazardous materials; hazardous waste and solid waste; National Historic Preservation 

Act and Executive Order 13007; environmental justice and impacted communities; 

Tribal consultation; children’s health and safety; indirect and cumulative impacts; 

mitigation and monitoring; and additional non-OCS activities;
Consultation and Coordination 5-5 

• Louisiana supports continued expansion of OCS oil and gas development, but 

requests that BOEM adequately address the cumulative, secondary, and indirect 

impacts of these activities and discuss compensatory mitigation for the impacts;

• the Consumer Energy Alliance supports the proposed action for the socioeconomic 

and national security benefits, and urges BOEM to reject requests to delay or prohibit 

leasing in the CPA; and

• BOEM should expand leasing to all areas of the Eastern Planning Area due to the 

socioeconomic benefits for the Nation and Gulf Coast.

5.3.2. Summary of Comments Received in Response to the Call for Information

In response to the Call, BOEM received two comment letters: one letter from the Louisiana 

Department of Natural Resources and one letter from the American Petroleum Institute. The Louisiana 

Department of Natural Resources hopes that BOEM will be more attentive to the State of Louisiana’s 

comments during the prelease planning phase, believes that a better appraisal of coastal effects is 

necessary, and believes that BOEM must more efficiently revisit reviews of earlier OCS lease sales to 

determine whether the models and predictive techniques used were accurate. The American Petroleum 

Institute states that annual, predictable lease sales in these planning areas are needed to help ensure 

continued offshore exploration and production in the future because production from lease sales will take 

many years to develop. The American Petroleum Institute further encourages BOEM to pursue 

legislation that will allow the entry into force of the “Agreement between the United States of America 

and the United Mexican States Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of 

Mexico” (Agreement). This Agreement will govern the development of reservoirs of petroleum and 

natural gas straddling the U.S.-Mexico maritime and continental shelf boundary in the Gulf of Mexico. 

Although the Agreement has received Congressional approval and the President’s signature, it has not yet 

entered into force. Please note that the United States and Mexico, by exchange of diplomatic notes on 

January 17, 2014, extended a treaty prohibition on exploration and development in the 1.4-nmi buffer 

zone until July 17, 2014, or the day the Agreement enters into force, whichever is sooner.

5.3.3. Additional Scoping Opportunities

Although the scoping process is formally initiated by the publication of the NOI and Call, scoping 

efforts and other coordination meetings have proceeded and will continue to proceed throughout this 

NEPA process. The Gulf of Mexico OCS Region’s Information Transfer Meetings provide an 

opportunity for BOEM’s analysts to attend technical presentations related to OCS Program activities and 

to meet with representatives from Federal, State, and local agencies; industry; BOEM contractors; and 

academia. Scoping and coordination opportunities were also available during BOEM’s requests for 

information, comments, input, and review of its other NEPA documents, included the following: 

• scoping and comments on the Five-Year Program EIS;

• requests for comments on the 2012-2017 WPA/CPA Multisale EIS; and

• scoping and comments on the WPA 233/CPA 231 Supplemental EIS. 

5.3.4. Cooperating Agency

According to Part 516 of the DOI Departmental Manual, BOEM must invite eligible governmental 

entities to participate as cooperating agencies when developing an EIS in accordance with the 

requirements of NEPA and the CEQ regulations. BOEM must also consider any requests by eligible 

government entities to participate as a cooperating agency with respect to a particular EIS, and then to 

either accept or deny such requests.

The NOI, which was published on August 23, 2013, included an invitation to other Federal agencies 

and State, Tribal, and local governments to consider becoming cooperating agencies in the preparation of 

this EIS. No Federal agencies or State, Tribal, or local governments requested to participate as a 

cooperating agency.
5-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

5.4. DISTRIBUTION OF THE DRAFT SUPPLEMENTAL EIS FOR REVIEW AND 

COMMENT

BOEM sent copies of the Draft Supplemental EIS to the government, public, and private agencies and 

groups listed below. Local libraries along the Gulf Coast were provided copies of this document; a list of 

these libraries is available on BOEM’s Internet website at http://www.boem.gov/EnvironmentalStewardship/Environmental-Assessment/NEPA/nepaprocess.aspx. 

Federal Agencies

Congress

Congressional Budget Office

House Resources Subcommittee on Energy 

and Mineral Resources

Senate Committee on Energy and Natural 

Resources

Department of Commerce

National Oceanic and Atmospheric 

Administration

National Marine Fisheries Service

Department of Defense

Corps of Engineers

Department of the Air Force

Department of the Army

Corps of Engineers

Department of the Navy

Naval Mine and Anti-Submarine 

Warfare Command

Department of Energy

Strategic Petroleum Reserve PMD

Department of Homeland Security

U.S. Coast Guard

Department of State

Bureau of Oceans and International 

Environmental and Scientific Affairs

Department of the Interior

Bureau of Ocean Energy Management

Fish and Wildlife Service

Geological Survey

National Park Service

Office of Environmental Policy and 

Compliance

Office of the Solicitor

Department of Transportation

Pipeline and Hazardous Materials Safety 

Administration

Office of Pipeline Safety

Environmental Protection Agency

Region 4

Region 6

Marine Mammal Commission

State and Local Agencies

Alabama

Governor’s Office

Alabama Highway Department

Alabama Historical Commission and State

Historic Preservation Officer

Alabama Public Service Commission

Department of Conservation and Natural 

Resources

Department of Environmental Management

South Alabama Regional Planning 

Commission

State Docks Department

State Legislature Natural Resources 

Committee

State Legislature Oil and Gas Committee

Florida

Governor’s Office

Bureau of Archaeological Research

City of Gulf Breeze

City of Panama City

City of Pensacola

Department of Economic Opportunity

Department of Environmental Protection

Department of State Archives, History and 

Records Management

Escambia County

Florida Coastal Zone Management Office 

Sarasota County Coastal Resources

State Legislature Natural Resources and 

Conservation Committee

State Legislature Natural Resources 

Committee

West Florida Regional Planning Council

Louisiana

Governor’s Office

City of Grand Isle

City of Morgan City

City of New Orleans

Department of Culture, Recreation, and 

Tourism

Department of Environmental Quality

Department of Natural Resources
Consultation and Coordination 5-7 

Department of Transportation and 

Development

Department of Wildlife and Fisheries

Houma-Terrebonne Chamber of Commerce

Jefferson Parish Director

Jefferson Parish President

Lafourche Parish CZM

Lafourche Parish Water District #1

Louisiana Geological Survey

South Lafourche Levee District

St. Bernard Planning Commission

State House of Representatives, Natural 

Resources Committee

State Legislature, Natural Resources 

Committee

Mississippi

Governor’s Office

City of Gulfport

Department of Archives and History

Department of Natural Resources

Department of Wildlife Conservation

Mississippi Development Authority

State Legislature Oil, Gas, and Other 

Minerals Committee

Industry

Alabama Petroleum Council

American Petroleum Institute

Area Energy LLC

Baker Atlas

Bellwether Group

B-J Services Co

BP Amoco

Chevron U.S.A. Inc.

Coastal Conservation Association

Coastal Environments, Inc.

Continental Shelf Associates, Inc.

Dominion Exploration & Production, Inc.

Ecological Associates, Inc.

Ecology and Environment

Energy Partners, Ltd.

EOG Resources, Inc.

Exxon Mobil Production Company

Freeport-McMoRan, Inc.

Fugro Geo Services, Inc.

Gulf Environmental Associates

Gulf of Mexico Newsletter

Horizon Marine, Inc.

Industrial Vehicles International, Inc.

International Association of Geophysical 

Contractors 

J. Connor Consultants

John Chance Land Surveys, Inc.

Marine Safety Office

Midstream Fuel Service

Murphy Exploration & Production

Newfield Exploration Company

Petrobras America, Inc.

PPG Industries, Inc.

Propane Market Strategy Newsletter

Science Applications International 

Corporation

Seneca Resources Corporation

Shell Exploration & Production Company

Stone Energy Corporation

Strategic Management Services-USA

T. Baker Smith, Inc.

Texas Geophysical Company, Inc.

The Houston Exploration Company

The Washington Post

Triton Engineering Services Co.

W & T Offshore, Inc.

WEAR-TV

Special Interest Groups

Alabama Oil & Gas Board

Alabama Wildlife Federation

American Cetacean Society

Apalachee Regional Planning Council

Audubon of Florida

Audubon Louisiana Nature Center

Capital Region Planning Commission

Center for Marine Conservation

Clean Gulf Associates

Coalition to Restore Coastal Louisiana

Coastal Conservation Association

Concerned Shrimpers of America

Earthjustice

Gulf and South Atlantic Fisheries

Foundation, Inc.

Gulf Coast Environmental Defense

Gulf Restoration Network

Houma-Terrebonne Chamber of Commerce

Izaak Walton League of America, Inc.

JOC Venture

LA 1 Coalition, Inc.

Louisiana Wildlife Federation

Marine Mammal Commission

Mission Enhancement Office

Mobile Area Chamber of Commerce

Mobile Bay National Estuary Program

Natural Resources Defense Council

Nature Conservancy

Offshore Operators Committee

Organized Fishermen of Florida

Population Connection

Portersville Revival Group
5-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

Restore or Retreat

Roffers Ocean Fishing Forecast Service

Ports/Docks

Alabama

Alabama State Port Authority

Port of Mobile

Louisiana

Abbeville Harbor and Terminal District

Grand Isle Port Commission

Greater Baton Rouge Port Commission

Greater Lafourche Port Commission

Lake Charles Harbor and Terminal District

Plaquemines Port, Harbor and Terminal 

District

Port of Baton Rouge

Port of Iberia District

Port of New Orleans

Twin Parish Port Commission

St. Bernard Port, Harbor and Terminal 

District

West Cameron Port Commission

Mississippi

Greenville Port Commission

Mississippi State Port Authority

Port of Gulfport

Educational Institutions/Research Laboratories

Dauphin Island Sea Laboratory

Foley Elementary School

Gulf Coast Research Laboratory

Jackson State University

Louisiana Sea Grant College Program

Louisiana State University

Louisiana Tech University

Louisiana Universities Marine Consortium

Loyola University

McNeese State University

Mississippi-Alabama Sea Grant Consortium

Mississippi State University

Mote Marine Laboratory

Nicholls State University

Pensacola Junior College

Tulane University

University of Alabama

University of Florida

University of Miami

University of New Orleans

University of South Alabama

University of South Florida

University of Southern Mississippi

University of Texas at Arlington

University of Texas at Austin

University of Texas Law School

University of Texas Libraries

University of West Florida

5.5. COASTAL ZONE MANAGEMENT ACT

If a Federal agency’s activities or development projects within or outside of the coastal zone will have 

reasonably foreseeable coastal effects in the coastal zone, then the activity is subject to a Federal 

Consistency Determination (CD). A consistency review will be performed pursuant to the Coastal Zone 

Management Act (CZMA) and CD’s will be prepared for the each CZMA State prior to each of the

proposed CPA lease sales. To prepare the CD’s, BOEM reviews each CZMA State’s Coastal 

Management Plan (CMP) and analyzes the potential impacts as outlined in this Supplemental EIS, new 

information, and applicable studies as they pertain to the enforceable policies of each CMP. The CZMA 

requires that Federal actions that are reasonably likely to affect any land or water use or natural resource 

of the coastal zone be “consistent to the maximum extent practicable” with relevant enforceable policies 

of the State’s federally approved coastal management program (15 CFR part 930 subpart C).

Based on these and other analyses, BOEM’s Director makes an assessment of consistency, which is 

then sent to each State with the Proposed Notice of Sale. If a State concurs, BOEM can proceed with the 

lease sale. A State’s concurrence may be presumed when a State does not provide a response within the 

60-day review period. A State may request an extension of time to review the CD within the 60-day 

period, which the Federal agency shall approve for an extension of 15 days or less. If a State objects, it 

must do the following under the CZMA: (1) indicate how BOEM’s prelease proposal is inconsistent with 

their CMP and suggest alternative measures to bring BOEM’s proposal into consistency with their CMP; 

or (2) describe the need for additional information that would allow a determination of consistency. In 

the event of an objection, the Federal and State agencies should use the remaining portion of the 90-day 

review period to attempt to resolve their differences (15 CFR § 930.43(b)). At the end of the 90-day 

review period, the Federal agency shall not proceed with the activity over a State agency’s objection 

unless the Federal agency concludes that, under the “consistent to the maximum extent practicable” 

standard described in 15 CFR § 930.32, consistency with the enforceable policies of the CMP is 
Consultation and Coordination 5-9 

prohibited by existing law applicable to the Federal agency and the Federal agency has clearly described, 

in writing, to the State agency the legal impediments to full consistency; or, the Federal agency has 

concluded that its proposed action is fully consistent with the enforceable policies of the CMP, though the 

State agency objects. Unlike the consistency process for specific OCS plans and permits, there is no 

procedure for administrative appeal to the Secretary of Commerce for a Federal CD for prelease activities. 

In the event that there is a serious disagreement between BOEM and a State, either agency may request 

mediation. Mediation is voluntary, and the Department of Commerce would serve as the mediator. 

Whether there is mediation or not, the final CD is made by DOI, and it is the final administrative action 

for the prelease consistency process. Each Gulf State’s CMP is described in Appendix F of the 2012-

2017 WPA/CPA Multisale EIS.

5.6. ENDANGERED SPECIES ACT

The Endangered Species Act of 1973 (ESA) (16 U.S.C. §§ 1631 et seq.) establishes a national policy 

designed to protect and conserve threatened and endangered species and the ecosystems upon which they 

depend. BOEM is currently in consultation with NMFS and FWS regarding the OCS oil and gas program 

in the Gulf of Mexico, including as it relates to the CPA proposed actions. BOEM is acting as the lead 

agency in the ongoing consultation, with BSEE’s assistance and involvement. The programmatic 

consultation was expanded in scope after the reinitiation of consultation by BOEM following the 

Deepwater Horizon explosion and oil spill, and it will include both existing and future OCS oil and gas 

leases in the Gulf of Mexico through 2022. This consultation also considers any changes in baseline 

environmental conditions following the Deepwater Horizon explosion, oil spill, and response. The 

programmatic consultation will also include postlease activities associated with OCS oil and gas activities 

in the Gulf of Mexico, including G&G and decommissioning activities. While the programmatic 

Biological Opinion is in development, BOEM and NMFS have agreed to interim consultations on 

postlease approvals.

With consultation ongoing, BOEM and BSEE will continue to comply with all reasonable and 

prudent measures and the terms and conditions under the existing consultations, along with implementing 

the current BOEM- and BSEE-required mitigation, monitoring, and reporting requirements. Based on the 

most recent and best available information at the time, BOEM and BSEE will also continue to closely 

evaluate and assess risks to listed species and designated critical habitat in upcoming environmental 

compliance documentation under NEPA and other statutes.

5.7. MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT ACT

Pursuant to Section 305(b) of the Magnuson-Stevens Fishery Conservation and Management Act, 

Federal agencies are required to consult with NMFS on any action that may result in adverse effects to 

essential fish habitat (EFH). The NMFS published the final rule implementing the EFH provisions of the 

Magnuson-Stevens Fisheries Conservation and Management Act (50 CFR part 600) on January 17, 2002. 

Certain OCS activities authorized by BOEM may result in adverse effects to EFH, and therefore, require 

EFH consultation.

Following the Deepwater Horizon explosion, oil spill, and response, NMFS requested a 

comprehensive review of the existing EFH consultation in a response letter dated September 24, 2010. In 

light of this request, Regional staff of BOEM and NMFS agreed on procedures that would incorporate a 

new programmatic EFH consultation into each prepared Five-Year Program EIS and that began with the 

2012-2017 Five-Year Program. BOEM has an EFH Assessment (Appendix D of the 2012-2017 

WPA/CPA Multisale EIS) that describes the OCS proposed activities, analyzes the effects of the proposed 

activities on EFH, and identifies proposed mitigating measures. The programmatic EFH consultation, 

which covers proposed CPA Lease Sales 235, 241, and 247 was initiated with the distribution and review 

of the 2012-2017 WPA/CPA Multisale EIS and with the subsequent written communications between 

BOEM and NMFS. These documents formalized the conservation recommendations put forth by NMFS 

and by BOEM’s acceptance and response to these recommendations. While the necessary components of 

the EFH consultation are complete (as per BOEM’s June 8, 2012, response letter to NMFS), there is 

ongoing coordination among NMFS, BOEM, and BSEE. This coordination includes annual reports from 

BOEM to NMFS, meetings with Regional staff, and discussions of mitigation and relevant topics. All 

agencies will continue to communicate for the duration of the Five-Year Program.
5-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

5.8. NATIONAL HISTORIC PRESERVATION ACT

In accordance with the National Historic Preservation Act (16 U.S.C. § 470 et seq.), Federal agencies 

are required to consider the effect of their undertakings on historic properties. The implementing 

regulations for Section 106 of the National Historical Preservation Act (16 U.S.C. § 470f), issued by the 

Advisory Council on Historic Preservation (16 CFR part 800), specify the required review process.

This Agency initiated a request for consultation on the 2012-2017 WPA/CPA Multisale EIS on 

November 12, 2010, via a formal letter. That letter was addressed to each of the affected Gulf Coast 

States and Tribal Nations, including the Alabama-Coushatta Tribes of Texas, Chitimacha Tribe of 

Louisiana, Choctaw Nation of Oklahoma, Coushatta Indian Tribe, Jena Band of Choctaw Indians, 

Miccosukee Indian Tribe of Florida, Mississippi Band of Choctaw Indians, Poarch Band of Creek 

Indians, Seminole Tribe of Florida, and Tunica-Biloxi Indian Tribe of Louisiana. A response timeline of 

30 days was provided and three responses were received.

The State of Louisiana, in a letter to this Agency dated December 16, 2010, indicated that no known 

historic properties on State land or within State waters will be affected by this undertaking and that 

consultation regarding the CPA proposed actions is not necessary. The State of Alabama, in a letter to 

BOEM referencing proposed WPA Lease Sale 233 and proposed CPA Lease Sale 231 dated July 18, 

2012, requested that a “Maritime Cultural Resource Assessment which meets the AHC [Alabama 

Historical Commission] standards should be conducted for any action within these sale blocks” and that 

the resulting report should be forwarded to their office for review and approval. Additional 

correspondence with the State of Alabama explained that cultural resource assessments are completed as 

part of BOEM’s postlease requirements and that they are site specific and are completed prior to 

authorization or approval of all proposed oil and gas activities. When necessary, cultural resource reports 

are also forwarded to the appropriate State agency as part of the Section 106 consultation process. A 

subsequent letter from the State of Alabama, dated August 16, 2012, agreed with the proposed lease 

actions, provided that submerged cultural resources are addressed prior to disturbance, as outlined above.

The Seminole Tribe of Florida-Tribal Historic Preservation Officer (STOF-THPO) responded to this 

Agency’s request for consultation on December 6, 2010. The STOF-THPO indicated that there was no 

objection to the proposed undertakings at this time. The STOF-THPO requested to review the impending 

remote-sensing survey reports that are to be conducted over the high-probability zones within the project 

area. Additionally, the STOF-THPO requested to be notified if cultural resources that are potentially 

ancestral or historically relevant to the Seminole Tribe of Florida are inadvertently discovered at any 

point during this process.

None of the above-referenced responses requested consultation. No further responses were received 

beyond the 30-day timeline and no requests for consultation were received. BOEM will continue to 

impose mitigating measures and monitoring and reporting requirements to ensure that historic properties 

are not affected by the proposed undertakings. BOEM will reinitiate the consultation process with the 

affected parties should such circumstances warrant further consultation.
CHAPTER 6 

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Prepared by ENVIRON International Corporation, Novato, CA. September 1, 2004.
References Cited 6-55

Yoshioka, P.M. and B.B. Yoshioka. 1987. Variable effects of Hurricane David on the shallow water 

gorgonians of Puerto Rico. Bulletin of Marine Science 40(1):132-144.

Yuro, A.M. 2011. The impact of storm surge from successive hurricanes on the Alabama beach mouse 

population. M.S. Thesis, Geography Dept., University of Alabama, Tuscaloosa.

Zengel, S. and J. Michel. 2013. Deepwater Horizon oil spill: Salt marsh oiling conditions, treatment 

testing, and treatment history in northern Barataria Bay, Louisiana (Interim Report October 2011). 

U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Emergency Response 

Division, Seattle, WA. NOAA Technical Memorandum NOS OR&R 42. 74 pp.

Zenz House, K., D.P. Schrag, C.F. Harvey, and K.A. Lackner. 2006. Permanent carbon dioxide storage 

in deep-sea sediments. Proceedings of the National Academy of Sciences 103(33):12291-12295.

Zieman, J.C. 1976. The ecological effects of physical damage from motor boats on turtle grass beds in 

Southern Florida. Aquatic Botany 2:127-139.

Zieman, J.C., R. Orth, R.C. Phillips, G. Thayer, and A. Thorhaug. 1984. The effects of oil on seagrass 

ecosystems. In: Cairns, J., Jr. and A.L. Buikema, Jr., eds. Restoration of habitats impacted by oil 

spills. Boston, MA: Butterworth Publishers.

Zuijdgeest, A. and M. Huettel. 2012. Dispersants as used in response to the MC252-spill lead to higher 

mobility of polycyclic aromatic hydrocarbons in oil-contaminated Gulf of Mexico sand. PLoS ONE 

7(11):e50549. doi:10.1371/journal.pone.0050549.

CHAPTER 7 

PREPARERS

Preparers 7-3 

7. PREPARERS

Gary D. Goeke, Chief, Regional Assessment Section

Lissa Lyncker, Unit Supervisor, Environmental Scientist

Tershara Matthews, Unit Supervisor, Environmental Scientist

Brian Cameron, NEPA Coordinator, Senior Environmental Scientist

Poojan Tripathi, Headquarters’ Coordinator, Environmental Protection Specialist

Pat Adkins, Information Management Specialist

Bruce Baird, Marine Biologist

Mark Belter, Marine Biologist

Darice Breeding, Environmental Protection Specialist

Alicia Caporaso, Marine Archaeologist

Bruce Cervini, Physical Scientist

Sindey Chaky, Environmental Protection Specialist

Ross Del Rio, Environmental Scientist

Chris DuFore, Oceanographer

Donald (Tre) W. Glenn III, Protected Species Biologist

Allison Hernandez, Protected Species Biologist

Jose Hernandez, Physical Scientist

Mark Jensen, Economist

Jack Irion, Unit Supervisor, Marine Archaeologist

Agatha-Marie Kaller, Unit Supervisor, Marine Biologist

Carla Langley, Geographer

Jessica Mallindine, Protected Species Biologist

Stacie Merritt, Physical Scientist

Margaret Metcalf, Unit Supervisor, Physical Scientist

Deborah H. Miller, Technical Editor

Megan Milliken, Economist

Mike Miner, Geologist

David P. Moran, Biologist

Michelle Nannen, Marine Biologist

S. Erin O’Reilly, Physical Scientist

Steve Pomes, Librarian

Catherine A. Rosa, Environmental Assessment Program Specialist

Scott Sorset, Marine Archaeologist

Ariel White, Environmental Scientist

CHAPTER 8 

GLOSSARY

Glossary 8-3 

8. GLOSSARY

Acute—Sudden, short term, severe, critical, 

crucial, intense, but usually of short duration.

Anaerobic—Capable of growing in the absence of 

molecular oxygen.

Annular preventer—A component of the 

pressure control system in the BOP that forms 

a seal in the annular space around any object 

in the wellbore or upon itself, enabling well 

control operations to commence.

Anthropogenic—Coming from human sources, 

relating to the effect of humankind on nature.

API gravity—A standard adopted by the 

American Petroleum Institute for expressing 

the specific weight of oil.

Aromatic—Class of organic compounds 

containing benzene rings or benzenoid 

structures.

Attainment area—An area that is shown by 

monitored data or by air-quality modeling 

calculations to be in compliance with primary 

and secondary ambient air quality standards 

established by USEPA.

Barrel (bbl)—A volumetric unit used in the 

petroleum industry; equivalent to 42 U.S. 

gallons or 158.99 liters.

Benthic—On or in the bottom of the sea.

Biological Opinion—The FWS or NMFS 

evaluation of the impact of a proposed action 

on endangered and threatened species, in 

response to formal consultation under 

Section 7 of the Endangered Species Act.

Block—A geographical area portrayed on official 

BOEM protraction diagrams or leasing maps 

that contains approximately 2,331 ha (9 mi2

). 

Blowout—An uncontrolled flow of fluids below 

the mudline from appurtenances on a wellhead 

or from a wellbore.

Blowout preventer (BOP)—One of several 

valves installed at the wellhead to prevent the 

escape of pressure either in the annular space 

between the casing and drill pipe or in open 

hole (i.e., hole with no drill pipe) during 

drilling completion operations. Blowout 

preventers on jackup or platform rigs are 

located at the water’s surface; on floating 

offshore rigs, BOP’s are located on the 

seafloor.

Bottom kill—A wild well-control procedure 

involving the intersection of an uncontrolled 

well with a relief well for the purpose of 

pumping heavy mud or cement into the wild 

well to stanch the flow of oil or gas (the wellcontrol strategy for the Macondo spill 

deployed in mid-July 2010 that resulted in the 

successful capping of the well). 

Cetacean—Aquatic mammal of the order Cetacea, 

such as whales, dolphins, and porpoises.

Chemosynthetic—Organisms that obtain their 

energy from the oxidation of various inorganic 

compounds rather than from light 

(photosynthetic).

Coastal waters—Waters within the geographical 

areas defined by each State’s Coastal Zone 

Management Program.

Coastal wetlands—forested and nonforested 

habitats, mangroves, and marsh islands 

exposed to tidal activity. These areas directly 

contribute to the high biological productivity 

of coastal waters by input of detritus and 

nutrients, by providing nursery and feeding 

areas for shellfish and finfish, and by serving 

as habitat for birds and other animals.

Coastal zone—The coastal waters (including the 

lands therein and thereunder) and the adjacent 

shorelands (including the waters therein and 

thereunder) strongly influenced by each other 

and in proximity to the shorelines of several 

coastal states; the zone includes islands, 

transitional and intertidal areas, salt marshes, 

wetlands, and beaches, and it extends seaward 

to the outer limit of the United States 

territorial sea. The zone extends inland from 

the shorelines only to the extent necessary to 

control shorelands, the uses of which have a 

direct and significant impact on the coastal 

waters. Excluded from the coastal zone are 

lands the use of which is by law subject to the 

discretion of or which is held in trust by the 

Federal Government, its officers, or agents. 

See also State coastal zone boundaries.

Completion—Conversion of a development well 

or an exploration well into a production well.

Condensate—Liquid hydrocarbons produced with

natural gas; they are separated from the gas by 

cooling and various other means. Condensates 

generally have an API gravity of 50o

-120o. 
8-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

Continental margin—The ocean floor that lies 

between the shoreline and the abyssal ocean 

floor, includes the continental shelf, 

continental slope, and continental rise.

Continental shelf—General term used by 

geologists to refer to the continental margin 

province that lies between the shoreline and 

the abrupt change in slope called the shelf 

edge, which generally occurs in the Gulf of 

Mexico at about the 200-m (656-ft) water 

depth. The continental shelf is characterized 

by a gentle slope (about 0.1o

). This is 

different from the juridical term used in 

Article 76 of the Convention on the Law of the 

Sea (see the definition of Outer Continental 

Shelf). 

Continental slope—The continental margin 

province that lies between the continental 

shelf and continental rise, characterized by a 

steep slope (about 3o

-6o). 

Critical habitat—Specific areas essential to the 

conservation of a protected species and that 

may require special management 

considerations or protection.

Crude oil—Petroleum in its natural state as it 

emerges from a well or after it passes through 

a gas-oil separator, but before refining or 

distillation. An oily, flammable, bituminous 

liquid that is essentially a complex mixture of 

hydrocarbons of different types with small 

amounts of other substances.

Delineation well—A well that is drilled for the 

purpose of determining the size and/or volume 

of an oil or gas reservoir. 

Demersal—Living at or near the bottom of the 

sea.

Development—Activities that take place 

following discovery of economically 

recoverable mineral resources, including 

geophysical surveying, drilling, platform 

construction, operation of onshore support 

facilities, and other activities that are for the 

purpose of ultimately producing the resources.

Development and Production Plan (DPP)—A 

document that must be prepared by the 

operator and submitted to BOEM for approval 

before any development and production 

activities are conducted on a lease or unit in 

any OCS area other than the western Gulf of 

Mexico.

Development Operations Coordination 

Document (DOCD)—A document that must 

be prepared by the operator and submitted to 

BOEM for approval before any development

or production activities are conducted on a 

lease in the western Gulf of Mexico.

Development well—A well drilled to a known 

producing formation to extract oil or gas; a 

production well; distinguished from a wildcat 

or exploration well and from an offset well.

Direct employment—Consists of those workers 

involved the primary industries of oil and gas 

exploration, development, and production 

operations (Standard Industrial Classification 

Code 13—Oil and Gas Extraction).

Discharge—Something that is emitted; flow rate 

of a fluid at a given instant expressed as 

volume per unit of time.

Dispersant—A suite of chemicals and solvents 

used to break up an oil slick into small 

droplets, which increases the surface area of 

the oil and hastens the processes of weathering 

and microbial degradation.

Dispersion—A suspension of finely divided 

particles in a medium.

Drilling mud—A mixture of clay, water or 

refined oil, and chemical additives pumped 

continuously downhole through the drill pipe 

and drill bit, and back up the annulus between 

the pipe and the walls of the borehole to a 

surface pit or tank. The mud lubricates and 

cools the drill bit, lubricates the drill pipe as it 

turns in the wellbore, carries rock cuttings to 

the surface, serves to keep the hole from 

crumbling or collapsing, and provides the 

weight or hydrostatic head to prevent 

extraneous fluids from entering the well bore 

and to downhole pressures; also called drilling 

fluid.

Economically recoverable resources—An 

assessment of hydrocarbon potential that takes 

into account the physical and technological 

constraints on production and the influence of 

costs of exploration and development and 

market price on industry investment in OCS 

exploration and production.

Effluent—The liquid waste of sewage and 

industrial processing.

Effluent limitations—Any restriction established 

by a State or the USEPA on quantities, rates, 

and concentrations of chemical, physical, 
Glossary 8-5 

biological, and other constituents discharged 

from point sources into U.S. waters, including 

schedules of compliance.

Epifaunal—Animals living on the surface of hard 

substrate.

Essential habitat—Specific areas crucial to the 

conservation of a species and that may 

necessitate special considerations.

Estuary—Coastal semienclosed body of water 

that has a free connection with the open sea 

and where freshwater meets and mixes with 

seawater.

Eutrophication—Enrichment of nutrients in the 

water column by natural or artificial methods 

accompanied by an increase of respiration, 

which may create an oxygen deficiency.

Exclusive Economic Zone (EEZ)—The maritime 

region extending 200 nmi (230 mi; 370 km)

from the baseline of the territorial sea, in 

which the United States has exclusive rights 

and jurisdiction over living and nonliving 

natural resources.

Exploration Plan (EP)—A plan that must be 

prepared by the operator and submitted to 

BOEM for approval before any exploration or 

delineation drilling is conducted on a lease.

Exploration well—A well drilled in unproven or 

semi-proven territory to determining whether 

economic quantities of oil or natural gas 

deposit are present.

False crawls—Refers to when a female sea turtle 

crawls up on the beach to nest (perhaps) but 

does not and returns to the sea without laying 

eggs.

Field—An accumulation, pool, or group of pools 

of hydrocarbons in the subsurface. A 

hydrocarbon field consists of a reservoir in a 

shape that will trap hydrocarbons and that is 

covered by an impermeable, sealing rock.

Floating production, storage, and offloading 

(FPSO) system—A tank vessel used as a 

production and storage base; produced oil is 

stored in the hull and periodically offloaded to 

a shuttle tanker for transport to shore.

Gathering lines—A pipeline system used to bring 

oil or gas production from a number of 

separate wells or production facilities to a 

central trunk pipeline, storage facility, or 

processing terminal.

Geochemical—Of or relating to the science 

dealing with the chemical composition of and 

the actual or possible chemical changes in the 

crust of the earth.

Geophysical survey—A method of exploration in 

which geophysical properties and relationships 

are measured remotely by one or more 

geophysical methods.

Habitat—A specific type of environment that is 

occupied by an organism, a population, or a 

community.

Hermatypic coral—Reef-building corals that 

produce hard, calcium carbonate skeletons and 

that possess symbiotic, unicellular algae 

within their tissues.

Harassment—An intentional or negligent act or 

omission that creates the likelihood of injury 

to wildlife by annoying it to such an extent as 

to significantly disrupt normal behavior 

patterns that include, but are not limited to, 

feeding or sheltering.

Hydrocarbons—Any of a large class of organic 

compounds containing primarily carbon and 

hydrogen. Hydrocarbon compounds are 

divided into two broad classes: aromatic and 

aliphatics. They occur primarily in petroleum, 

natural gas, coal, and bitumens.

Hypoxia—Depressed levels of dissolved oxygen 

in water, usually resulting in decreased 

metabolism.

Incidental take—Takings that result from, but are 

not the purpose of, carrying out an otherwise 

lawful activity (e.g., fishing) conducted by a 

Federal agency or applicant (see Taking).

Indirect employment—Secondary or supporting 

oil- and gas-related industries, such as the 

processing of crude oil and gas in refineries, 

natural gas plants, and petrochemical plants.

Induced employment—Tertiary industries that 

are created or supported by the expenditures of 

employees in the primary or secondary 

industries (direct and indirect employment), 

including consumer goods and services such 

as food, clothing, housing, and entertainment.

Infrastructure—The facilities associated with oil 

and gas development, e.g., refineries, gas 

processing plants, etc.

Jack-up rig—A barge-like, floating platform with 

legs at each corner that can be lowered to the 
8-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

sea bottom to raise the platform above the 

water.

Kick—A deviation or imbalance, typically sudden 

or unexpected, between the downward 

pressure exerted by the drilling fluid and the 

upward pressure of in-situ formation fluids or 

gases.

Landfall—The site where a marine pipeline 

comes to shore.

Lease—Authorization that is issued under 

Section 8 or maintained under Section 6 of the 

Outer Continental Shelf Lands Act and that 

authorizes exploration for, and development 

and production of, minerals.

Lease sale—The competitive auction of leases 

granting companies or individuals the right to 

explore for and develop certain minerals under 

specified conditions and periods of time.

Lease term—The initial period for oil and gas 

leases, usually a period of 5, 8, or 10 years 

depending on water depth or potentially 

adverse conditions.

Lessee—A party authorized by a lease, or an 

approved assignment thereof, to explore for 

and develop and produce the leased deposits in 

accordance with regulations at 30 CFR 250

and 30 CFR 550. 

Lower marine riser package—The head 

assembly of a subsurface well at the point 

where the riser connects to a blowout 

preventer.

Macondo—Prospect name given by BP to the 

Mississippi Canyon Block 252 exploration 

well that the Deepwater Horizon rig was 

drilling when a blowout occurred on April 20, 

2010.

Macondo spill—The name given to the oil spill 

that resulted from the explosion and sinking of 

the Deepwater Horizon rig from the period 

between April 24, 2010, when search and 

recovery vessels on site reported oil at the sea 

surface, and September 19, 2010, when the 

uncontrolled flow from the Macondo well was 

capped. 

Marshes—Persistent, emergent, nonforested 

wetlands characterized by predominantly 

cordgrasses, rushes, and cattails.

Military warning area—An area established by 

the U.S. Department of Defense within which 

military activities take place.

Minerals—As used in this document, minerals 

include oil, gas, sulphur, and associated 

resources, and all other minerals authorized by 

an Act of Congress to be produced from 

public lands as defined in Section 103 of the 

Federal Land Policy and Management Act of 

1976.

Naturally occurring radioactive materials 

(NORM)—naturally occurring material that 

emits low levels of radioactivity, originating 

from processes not associated with the 

recovery of radioactive material. The 

radionuclides of concern in NORM are 

Radium-226, Radium-228, and other isotopes 

in the radioactive decay chains of uranium and 

thorium.

Nepheloid—A layer of water near the bottom that 

contains significant amounts of suspended 

sediment.

Nonattainment area—An area that is shown by 

monitoring data or by air-quality modeling 

calculations to exceed primary or secondary 

ambient air quality standards established by 

USEPA.

Nonhazardous oil-field wastes (NOW)—Wastes 

generated by exploration, development, or 

production of crude oil or natural gas that are 

exempt from hazardous waste regulation under 

the Resource Conservation and Recovery Act 

(Regulatory Determination for Oil and Gas 

and Geothermal Exploration, Development 

and Production Wastes, dated June 29, 1988, 

53 FR 25446; July 6, 1988). These wastes 

may contain hazardous substances.

Offloading—Unloading liquid cargo, crude oil, or 

refined petroleum products.

Operational discharge—Any incidental 

pumping, pouring, emitting, emptying, or 

dumping of wastes generated during routine 

offshore drilling and production activities.

Operator—An individual, partnership, firm, or 

corporation having control or management of 

operations on a leased area or portion thereof. 

The operator may be a lessee, designated 

agent of the lessee, or holder of operating 

rights under an approved operating agreement.

Organic matter—Material derived from living 

plants or animals.

Outer Continental Shelf (OCS)—All submerged 

lands that comprise the continental margin 
Glossary 8-7 

adjacent to the United States and seaward of 

State offshore lands.

Pelagic—Of or pertaining to the open sea; 

associated with open water beyond the direct 

influence of coastal systems.

Plankton—Passively floating or weakly motile 

aquatic plants (phytoplankton) and animals 

(zooplankton).

Platform—A steel or concrete structure from 

which offshore development wells are drilled.

Play—A prospective subsurface area for 

hydrocarbon accumulation that is 

characterized by a particular structural style or 

depositional relationship.

Primary production—Organic material produced 

by photosynthetic or chemosynthetic 

organisms.

Produced water—Total water discharged from 

the oil and gas extraction process; production 

water or production brine.

Production—Activities that take place after the 

successful completion of any means for the 

extraction of resources, including bringing the 

resource to the surface, transferring the 

produced resource to shore, monitoring 

operations, and drilling additional wells or 

workovers.

Province—A spatial entity with common geologic 

attributes. A province may include a single 

dominant structural element such as a basin or 

a fold belt, or a number of contiguous related 

elements.

Ram—The main component of a blowout 

preventer designed to shear casing and tools in 

a wellbore or to seal an empty wellbore. A 

blind shear ram accomplishes the former and a 

blind ram the latter.

Recoverable reserves—The portion of the 

identified hydrocarbon or mineral resource 

that can be economically extracted under 

current technological constraints.

Recoverable resource estimate—An assessment 

of hydrocarbon or mineral resources that takes 

into account the fact that physical and 

technological constraints dictate that only a 

portion of resources can be brought to the 

surface.

Recreational beaches—Frequently visited, sandy 

areas along the Gulf of Mexico shorefront that 

support multiple recreational activities at the 

land-water interface. Included are National 

Seashores, State Park and Recreational Areas, 

county and local parks, urban beachfronts, and 

private resorts.

Refining—Fractional distillation of petroleum, 

usually followed by other processing (e.g., 

cracking).

Relief—The difference in elevation between the 

high and low points of a surface.

Reserves—Proved oil or gas resources.

Rig—A structure used for drilling an oil or gas 

well.

Riser insertion tube tool—A “straw” and gasket 

assembly improvised during the Macondo spill 

response that was designed to siphon oil and 

gas from the broken riser of the Deepwater 

Horizon rig lying on the sea bottom (an early 

recovery strategy for the Macondo spill in 

May 2010). 

Royalty—A share of the minerals produced from 

a lease paid in either money or “in-kind” to the 

landowner by the lessee.

Saltwater intrusion—Saltwater invading a body 

of freshwater.

Sciaenids—Fishes belonging to the croaker family 

(Sciaenidae).

Seagrass beds—More or less continuous mats of 

submerged, rooted, marine, flowering vascular 

plants occurring in shallow tropical and 

temperate waters. Seagrass beds provide 

habitat, including breeding and feeding 

grounds, for adults and/or juveniles of many 

of the economically important shellfish and 

finfish. 

Sediment—Material that has been transported and 

deposited by water, wind, glacier, 

precipitation, or gravity; a mass of deposited 

material.

Seeps (hydrocarbon)—Gas or oil that reaches the 

surface along bedding planes, fractures, 

unconformities, or fault planes.

Sensitive area—An area containing species, 

populations, communities, or assemblages of 

living resources, that is susceptible to damage 

from normal OCS-related activities. Damage 

includes interference with established 

ecological relationships.

Shear ram—The component in a BOP that cuts, 

or shears, through the drill pipe and forms a 
8-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

seal against well pressure. Shear rams are 

used in floating offshore drilling operations to 

provide a quick method of moving the rig 

away from the hole when there is no time to 

trip the drill stem out of the hole.

Shoreline Cleanup and Assessment Team—The

on-the-scene responders for post-spill 

shoreline protection who established priorities, 

standardized procedures, and terminology. 

Spill of National Significance—Designation by 

the USEPA Administrator under 40 CFR 

300.323 for discharges occurring in the inland 

zone and the Commandant of the U.S. Coast 

Guard for discharges occurring in the coastal 

zone, authorizing the appointment of a 

National Incident Commander for spillresponse activity.

State coastal zone boundary—The State coastal 

zone boundaries for each CZMA-affected 

State are defined at http://

coastalmanagement.noaa.gov/mystate/docs/

StateCZBoundaries.pdf. 

Structure—Any OCS facility that extends from 

the seafloor to above the waterline; in 

petroleum geology, any arrangement of rocks 

that may hold an accumulation of oil or gas.

Subarea—A discrete analysis area.

Subsea isolation device—An emergency 

disconnection and reconnection assembly for 

the riser at the seafloor. 

Supply vessel—A boat that ferries food, water, 

fuel, and drilling supplies and equipment to an 

offshore rig or platform and returns to land 

with refuse that cannot be disposed of at sea.

Taking—To harass, harm, pursue, hunt, shoot, 

wound, kill, trap, capture, or collect any 

endangered or threatened species, or to attempt to 

engage in any such conduct (including actions that 

induce stress, adversely impact critical habitat, or 

result in adverse secondary or cumulative 

impacts). Harassments are the most common form 

of taking associated with OCS Program activities.

Tension-leg platform (TLP)—A production 

structure that consists of a buoyant platform 

tethered to concrete pilings on the seafloor 

with flexible cable.

Total dissolved solids—The total amount of 

solids that are dissolved in water.

Total suspended particulate matter—The total 

amount of suspended solids in water.

Total suspended solids—The total amount of 

suspended solids in water.

Trunkline—A large-diameter pipeline receiving 

oil or gas from many smaller tributary 

gathering lines that serve a large area; 

common-carrier line; main line.

Turbidity—Reduced water clarity due to the 

presence of suspended matter.

Volatile organic compound (VOC)—Any 

organic compound that is emitted to the 

atmosphere as a vapor.

Water test areas—Areas within the eastern Gulf 

where U.S. Department of Defense research, 

development, and testing of military planes, 

ships, and weaponry take place.

Weathering (of oil)—The aging of oil due to its 

exposure to the atmosphere, causing marked 

alterations in its physical and chemical 

makeup.
FIGURES

Figures Figures-3

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

Figures-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

Figure 2-1. Location of Proposed Stipulations and Deferrals.
Figures Figures-5

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

Figures-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

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

Tables Tables-3 

Table 3-1

Projected Oil and Gas in the Gulf of Mexico OCS

Typical Lease Sale OCS Cumulative 

(2012-2051)

Western Planning Area

 Reserve/Resource Production

 Oil (BBO) 0.116-0.200 2.510-3.696

 Gas (Tcf) 0.538-0.938 12.539-18.434

Central Planning Area

 Reserve/Resource Production

 Oil (BBO) 0.460-0.894 15.825-21.733

 Gas (Tcf) 1.939-3.903 63.347-92.691

Eastern Planning Area

 Reserve/Resource Production

 Oil (BBO) 0-0.071 0-0.211

 Gas (Tcf) 0-0.162 0-0.502

BBO = billion barrels of oil.

Tcf = trillion cubic feet.
Tables-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 3-2

Offshore Scenario Information Related to a Typical Lease Sale in the Central Planning Area

 

Offshore Subareas1

Total CPA2

0-60 m 60-200 m 200-800 m 800-1,600 m 1,600-2,400 m >2,400 m

Wells Drilled

 Exploration and Delineation Wells 62-121 24-46 21-42 15-29 18-36 28-55 168-329

 Development and Production Wells 78-152 32-58 26-53 20-38 24-46 35-70 215-417

 Producing Oil Wells 11-21 5-8 16-32 12-23 15-29 22-43 81-156

 Producing Gas Wells 58-115 23-44 7-15 5-10 6-11 9-19 108-241

Production Structures

 Installed 28-54 3-6 1-2 1 1-2 1-2 35-67

 Removed Using Explosives 18-36 2-4 0 0 0 0 20-40

 Total Removed 25-49 3-5 1-2 1 1-2 1-2 32-61

Method of Transportation3

 Percent Piped >99% >99% >99% >99% 90->99% 93->99%

 Percent Barged <1% 0% 0% 0% 0% <1%

 Percent Tankered4 0% 0% 0% 0% 0-10% 0-6%

Length of Installed Pipelines (km)5 216-586 NA NA NA NA NA 628-1870

Service-Vessel Trips (1,000’s round trips) 32-61 5-10 3-6 17-19 18-35 19-37 94-168

Helicopter Operations (1,000’s operations) 557-1,470 63-163 21-54 14-36 21-54 21-54 696-1,815

1 See Figure 3-1. 2 Subareas totals may not add up to the planning area total because of rounding.

3 100% of gas is assumed to be piped.

4 Tankering is forecasted to occur only in water depths >1,600 m (5,249 ft). 5 Projected length of pipelines does not include length in State waters.

NA = not available.
Tables Tables-5

Table 3-3

Offshore Scenario Information Related to OCS Program Activities

in the Gulf of Mexico (WPA, CPA, and EPA) for 2012-2051

 

Offshore Subareas1

Total OCS2

0-60 m 60-200 m 200-800 m 800-1,600 m 1,600-2,400 m >2,400 m

Wells Drilled

 Exploration and Delineation Wells 2,730-3,900 990-1,390 920-1,350 700-960 770-1,030 790-1,170 6,910-9,827

 Development and Production Wells 3,380-4,820 1240-1,730 1130-1670 860-1,190 950-1,280 970-1,450 8,530-12,180

 Producing Oil Wells 520-701 215-278 704-1030 574-783 663-873 620-915 3,296-4,605

 Producing Gas Wells 2,510-3,629 885-1272 306-470 196-287 187-267 250-385 4,334-6,320

Production Structures

 Installed 1,210-1,720 110-160 26-40 25-30 32-33 32-38 1,435-2,026

 Removed Using Explosives 796-1,139 69-104 3-4 0 0 0 868-1,247

 Total Removed 1,090-1,560 100-150 24-34 20-28 23-30 22-33 1,279-1,837

Method of Transportation3

 Percent Piped >99% >99% >99% >99% 87->99% 92->99%

 Percent Barged <1% 0% 0% 0% 0% <1%

 Percent Tankered4 0% 0% 0% 0% 0-13% 0-7%

Length of Installed Pipelines (km)5 10,482-21,121 NA NA NA NA NA 30,428-69,749

Service-Vessel Trips (1,000’s round trips) 1,366-1,942 196-280 111-162 466-619 584-626 587-719 3,310-4,382

Helicopter Operations (1,000’s operations) 24,221-47,322 2,297-4,444 595-1,174 574-1,111 676-1,287 888-1,738 28,710-55,605

1 See Figure 3-1. 2 Subareas totals may not add up to the planning area total because of rounding.

3 100% of gas is assumed to be piped.

4 Tankering is forecasted to occur only in water depths >1,600 m (5,249 ft). 5 Projected length of pipelines does not include length in State waters.

NA = not available.
Tables-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 3-4

Offshore Scenario Information Related to OCS Program Activities

in the Central Planning Area for 2012-2051

 

Offshore Subareas1

Total CPA2

0-60 m 60-200 m 200-800 m 800-1,600 m 1,600-2,400 m >2,400 m

Wells Drilled

 Exploration and Delineation Wells 2,230-3,160 820-1,160 700-1,030 540-730 700-940 730-1,090 5,720-8,110

 Development and Production Wells 2,760-3,900 1,020-1,440 860-1,270 670-900 870-1,160 900-1,350 7,080-10,020

 Producing Oil Wells 446-592 188-240 534-775 449-592 609-796 575-848 2,801-3,843

 Producing Gas Wells 2,034-2,918 722-1,050 236-365 151-218 171-244 235-362 3,549-5,157

Production Structures

 Installed 990-1,390 90-130 20-30 20-25 30 30-35 1,180-1,640

 Removed Using Explosives 650-920 55-83 2-3 0 0 0 707-1,006

 Total Removed 890-1,260 80-120 18-26 16-21 21-27 21-31 1,046-1,485

Method of Transportation3

 Percent Piped >99% >99% >99% >99% 90->99% 93->99%

 Percent Barged <1% 0% 0% 0% 0% >1%

 Percent Tankered4 0% 0% 0% 0% 0-10% 0-6%

Length of Installed Pipelines (km)5 8,515-16,993 NA NA NA NA NA 25,204-57,177

Service-Vessel Trips (1,000’s round trips) 1,117-1,570 161-230 85-126 371-469 546-569 549-663 2,829-3,627

Helicopter Operations (1,000’s operations) 19,975-37,825 1,902-3,560 404-801 404-668 595-801 595-890 23,780-44,500

1 See Figure 3-1. 2 Subareas totals may not add up to the planning area total because of rounding.

3 100% of gas is assumed to be piped.

4 Tankering is forecasted to occur only in water depths >1,600 m (5,249 ft). 5 Projected length of pipelines does not include length in State waters.

NA = not available.
Tables Tables-7 

Table 3-5 

Annual Volume of Produced Water Discharged by Depth

(millions of bbl)

Year Shelf

0-60 m

Shelf

60-200 m

Slope

200-400 

m

Deepwater

400-800 m

Deepwater

800-1,600 m

UltraDeepwater

1,601-2,400 m

UltraDeepwater

>2,400 m

Total

2000 370.6 193.1 35.5 25.6 12.2 0.0 0.0 637.0

2001 364.2 185.2 35.0 32.0 16.6 0.0 0.0 633.0

2002 344.6 180.4 32.5 35.2 21.4 0.0 0.0 614.1

2003 359.4 182.9 31.2 39.0 35.5 0.2 0.0 648.2

2004 346.7 160.5 29.3 36.9 39.2 1.9 0.0 614.5

2005 270.1 113.5 23.1 33.5 43.0 5.8 0.0 489.0

2006 260.3 99.7 20.6 35.1 61.5 12.4 0.0 489.6

2007 307.0 139.4 22.2 40.0 70.3 15.5 0.1 594.5

2008 252.7 118.6 15.9 32.7 60.1 16.5 0.1 496.6

2009 263.9 108.3 19.9 39.2 65.3 25.0 0.1 521.7

2010 275.8 115.7 20.9 40.7 56.7 32.5 0.1 542.4

2011 271.3 116.9 20.5 39.7 67.7 32.2 0.1 548.4

2012 237.2 109.0 20.8 35.0 71.3 31.8 0.1 505.2

Source: Langley, official communication, 2013.

Table 3-6

Annual Summary of Number and Total Volume of Oil Spilled into the Gulf of Mexico, 2001-2011

Year Number of Spills 

in the Gulf of Mexico

Volume of Spills in the Gulf of Mexico

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)

2011 498 483 (20,276)

Note: The volume does not include oil spilled in rivers that enter the Gulf of Mexico. The reported spills 

include spills of crude and refined hydrocarbon products.

Source: U.S. Dept. of Homeland Security, CG, 2012.
Tables-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 3-7

Waterway Length, Depth, Traffic, and Number of Trips for 2011

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 230 12 661 0 375

Panama City to Pensacola Bay, FL 187 12 1,812 0 1,306

Pensacola Bay, FL to Mobile Bay, AL 78 12 4,733 0 4,559

Mobile Bay, AL to New Orleans, LA 228 12, 14 17,295 0 21,952

Mississippi River, LA to Sabine River, TX 452 12, 10 63,384 0 52,470

Sabine River to Galveston, TX 143 12 59,132 0 33,756

Galveston to Corpus Christi, TX 322 11, 11, 10.2 25,561 0 19,333

Corpus Christi, TX to Mexican Border 226 10, 12, 7 2,212 0 1,641

Morgan City - Port Allen Route, LA 109 10 16,985 0 8,958

Florida Harbors, Channels, and Waterways

Escambia and Conecuh Rivers, FL and AL; 

Escambia Bay, FL

12 10 2,273 0 2,789

La Grange Bayou, FL 3 9 249 0 81

Panama City Harbor, FL 9 34, 32, 10 2,142 313 879

Pensacola Harbor, FL 21 35, 33, 15, 14 752 33 336

St. Marks River, FL 61 9 62 0 28

Tampa Harbor, FL 140.5 45, 43, 34, 12, 9 31,408 1,190 822

Port Manatee, FL 5.1 40 3,724 17 231

Alabama Harbors, Channels, and Waterways

Mobile Harbor, AL 71 47, 45, 40, 13-39 55,552 1,480 27,110

Theodore Ship Channel, AL 14 4 5,567 1,003 233

Mississippi Harbors, Channels, and Waterways

Biloxi Harbor, MS 39 12, 10, 12 1,612 2 1,828

Gulfport Harbor, MS 34 30, 32, 8 2,151 2,119 1,899

Pascagoula Harbor, MS 18 40, 38, 38, 22, 12 36,863 637 3,216

Bayou Casotte, MS 2 38 36,557 558 3,019

Louisiana Harbors, Channels, and Waterways

Atchafalaya River (Lower), LA 62 20 1,225 471 8,618

Barataria Bay Waterway, LA 71 16 156 0 3,056

Bayou Lafourche and Bayou LafourcheJump Waterway85 28, 27, 27, 9 4,754 2,083 15,037

Bayou Little Caillou, LA 56 12 134 0 473

Bayou Teche, LA 181 3,3,4,7 733 0 576

Bayou Teche and Vermilion River, LA 88 8,11,9,8,5 613 23 2,627

Bayou Terrebonne, LA 61 10 174 0 681

Calcasieu River and Pass, LA 186 42, 42, 41-42, 36, 12, 7 54,247 1,558 61,847
Tables Tables-9 

Source: U.S. Dept. of the Army, COE, 2011.

Table 3-7. Waterway Length, Depth, Traffic, and Number of Trips for 2011 (continued)

Waterway

Canal 

Length 

(km)

Maintained Depth 

(ft)

Traffic 

(1,000 

short tons)

Number of Trips

Foreign Domestic

Louisiana Harbors, Channels, and Waterways (continued)

Freshwater Bayou, LA 39 12 442 112 6,121

Houma Navigation Canal, LA 62 16, 15, 16 465 35 1,668

Mermentau River, LA 131 4, 7, 12, 10, 10, 9, 11, 

6, 8, 4, 4, 7

321 0 1,298

Mermentau River, Bayou Nezpique, and 

Des Cannes, LA

122 9, 14, 10 394 0 499

Mississippi River, Baton Rouge LA to the 

Mouth of Passes

461 - 446,346 233,019 5,611

Port of New Orleans, LA 88 45, 30, 32, 36, 37, 12 77,175 25,881 1,789

Port of Baton Rouge, LA 152 45, 40, 9, 12 57,872 51,140 51,797

Port of South Louisiana 91 45 246,509 78,410 2,528

Port of Plaquemines, LA 138 45 54,093 71,245 604

Passes of the Mississippi River, LA 60.18 13, 45 227,981 3,264 5596

Mississippi River Gulf Outlet via Venice 

Vicinity Consolidation

22 16, 14, 14 1,881 38 7,408

Petit Anse, Tigre, and Carlin Bayous 28 6, 9, 5, 7 2,724 0 2,943

Port of Iberia 14 13 2,200 NA NA

Port of Morgan City, LA - 12 1,558 212 10,363

Waterway from Empire, LA to the 

Gulf of Mexico

17 6, 9, 14 865 0 7,374

Waterway from Intracoastal Waterway 

to Bayou Dulac, LA

61 14 75 0 893

Texas Harbors, Channels, and Waterways

Brazos Island Harbor, TX 50 36.5, 31, 38, 12, 14, 7 5,907 236 1,273

Cedar Bayou, TX 23 11 1,177 0 1,075

Channel to Aransas Pass, TX 12 14 945 3 1,075

Channel to Port Bolivar, TX 17 12 0 18,111

Corpus Christi Ship Channel, TX 58 47, 45, 46, 47, 14, 9 70,538 1,415 99,280

Dickenson Bayou, TX 34 9 150 0 92

Freeport Harbor, TX 15 44, 37, 18, 40 23,312 866 2,966

Galveston Channel, TX 7 41 13,744 2,703 22,419

Houston Ship Channel, TX 119 45, 40, 32-39, 9, 7, 

35-37, 7, 40, 12

237,799 6,029 79,118

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

Texas City Channel, TX 14 43, 41, 42, 42 57,758 776 6,625
Tables-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 3-8

Number and Volume of Chemical and Synthetic-Based Fluid Spills 

in the Gulf of Mexico during 2005-2012

Spill Size 

(bbl)

2005 2006 2007 2008

Chemical SBF Chemical SBF Chemical SBF Chemical SBF

50-<100 3 0 1 1 0 0 5 0

100-<500 2 5 1 4 0 1 4 1

500-<1,000 1 0 0 0 1 0 3 0

>1,000 0 0 0 0 0 1 0 1

Spill Size 

(bbl)

2009 2010 2011 2012

Chemical SBF Chemical SBF Chemical SBF Chemical SBF

50-<100 1 1 0 2 0 1 1 2

100-<500 2 3 1 0 0 1 2 1

500-<1,000 0 0 0 0 0 0 1 0

>1,000 0 0 0 0 0 0 0 0

Notes: SBF = synthetic-based fluid.

The SBF fraction of the whole drilling fluid was recorded, not the total volume of drilling fluid.

Source: USDOI, BSEE, 2013.
Tables Tables-11

Table 3-9

Quantities of Dredged Materials Disposed of 

in Ocean Dredged-Material Disposal Sites between 2001 and 2010

Galveston District

Year Amount Disposed of in ODMDS

yd3 m3

2001 6,828,807 5,221,000

2002 4,874,468 3,726,800

2003 8,221,774 6,286,000

2004 4,079,104 3,118,700

2005 1,250,923 956,400

2006 9,182,594 7,020,600

2007 6,361,607 4,863,800

2008 5,665,124 4,331,300

2009 16,295,749 12,459,000

2010 6,226,627 4,760,600

Average 6,898,678 5,274,420

New Orleans District

Year Amount Disposed of in ODMDS

yd3 m3

2001 23,273,662 17,794,000

2002 57,646,327 44,073,800

2003 22,547,619 17,238,900

2004 21,157,530 16,176,100

2005 21,404,471 16,364,900

2006 13,494,251 10,317,100

2007 17,551,773 13,419,300

2008 16,801,795 12,845,900

2009 7,619,332 5,825,400

2010 15,386,985 11,764,200

Average 21,688,375 16,581,960

ODMDS = ocean dredged-material disposal sites.

Sources: U.S. Dept. of the Army, COE, 2002, 2003, 2004, 2005, 2006, 2007, 

2008, 2009, 2010a, and 2010b.
Tables-12 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 3-10

 

Number of Vessel Calls at U.S. Gulf Ports Between 2002 and 20111 

Vessel Type 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Tanker-Product2,3 5,100 5,143 5,764 6,171 6,594 6,784 6,597 6,451 7,000 8,413

Tanker - Crude2,4 3,698 4,227 4,361 4,303 4,343 4,614 4,574 4,502 5,150 5,626

Container 5 1,262 1,263 1,284 1,378 1,354 1,306 1,372 1,641 1,934 2,338

Dry Bulk6 4,983 4,837 4,959 4,575 5,289 4,988 4,563 4,021 3,475 3,917

RO-RO (Roll-on 

Roll-off)7 431 398 370 337 423 386 374 491 549 566

Gas8 514 624 548 558 622 628 462 441 500 604

Combo9 418 375 258 201 155 135 116 102 94 66

General10 1,267 1,167 1,141 1,160 1,246 1,362 1,363 1,300 1,387 1,459

All Types 17,673 18,034 18,685 18,683 20,026 20,203 19,421 18,949 20,089 22,989

 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% 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. 10 General cargo carriers, partial containerships, refrigerated ships, barge carriers, livestock carriers.

Source: USDOT, MARAD, 2013.
Tables Tables-13

Table 3-11

Corps of Engineers’ Galveston District Maintenance Dredging Activity 

for Federal Navigation Channels in Texas, 2001-2010*

Harbor, Channel, or Waterway Year Volume Dredged

yd3 m3

Sabine-Neches Waterway 2001 4,063,801 3,107,000

Freeport Harbor and Channel 2001 2,478,565 1,895,000

Matagorda Ship Channel 2001 285,656 218,400

Freeport Harbor and Channel 2002 1,996,455 1,526,400

Sabine-Neches Waterway 2002 2,878,013 2,200,400

Corpus Christi Ship Channel 2003 930,737 711,600

Sabine-Neches Waterway 2003 3,545,198 2,710,500

Freeport Harbor 2003 1,650,110 1,261,600

Galveston Harbor and Channel 2003 2,095,728 1,602,300

Freeport Harbor 2004 1,854,150 1,417,600

Matagorda Ship Channel 2004 365,180 279,200

Sabine-Neches Waterway 2004 1,859,774 1,421,900

Sabine-Neches Waterway 2005 1,062,709 812,500

Freeport Harbor 2005 188,214 143,900

Sabine-Neches Waterway 2006 1,523,762 1,165,000

Freeport Harbor 2006 3,427,221 2,620,300

Galveston Harbor and Channel 2006 3,744,661 2,863,000

Matagorda Ship Channel 2006 336,666 257,400

Corpus Christi Ship Channel 2006 149,760 114,500

Freeport Harbor 2007 2,427,817 1,856,200

Galveston Harbor 2007 2,939,094 2,247,100

Corpus Christi Ship Channel 2007 954,673 729,900

Sabine-Neches Waterway 2007 40,023 30,600

Sabine-Neches Waterway 2008 1,691,964 1,293,600

Freeport Harbor 2008 1,577,257 1,205,900

Galveston Harbor and Channel 2008 2,422,062 1,851,800

Freeport Harbor 2009 2,420,885 1,850,900

Corpus Christi Ship Channel 2009 118,108 90,300

Sabine-Neches Waterway 2009 5,811,876 4,443,500

Houston Ship Channel 2009 883,520 675,500

Galveston Harbor and Channel 2009 7,061,360 5,398,800

Corpus Christi Ship Channel 2010 791,964 605,500

Sabine-Neches Waterway 2010 2,669,395 2,040,900

Houston Ship Channel 2010 261,067 199,600

Galveston Harbor and Channel 2010 2,066,823 1,580,200

Freeport Harbor 2010 429,923 328,700

Total 69,004,172 52,757,500

* Dredged material disposed of in Ocean Dredged-Material Disposal Site.

Sources: U.S. Dept. of the Army, COE, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010a, and 2010b.
Tables-14 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 3-12

Corps of Engineers’ New Orleans District Maintenance Dredging Activity 

for Federal Navigation Channels in Louisiana, 2001-2010*

Harbor, Channel, or Waterway Year Volume Dredged

yd3 m3

Atchafalaya River Bar Channel, St. Mary Parish -

Atchafalaya River and Bayous Chene, Boeuf, and Black, LA 2001 14,371,885 10,988,100

Calcasieu River Bar Channel, Cameron Parish 2001 240,532 183,900

Mississippi River Gulf Outlet Bar Channel 2001 1,449,732 1,108,400

Mississippi River, Baton Rouge to Southwest Pass 2001 7,211,513 5,513,600

Atchafalaya River Bar Channel, St. Mary Parish -

Atchafalaya River and Bayous Chene, Boeuf, and Black, LA 2002 29,644,948 22,665,200

Mississippi River, Baton Rouge to Southwest Pass 2002 15,758,312 12,048,100

Mississippi River Gulf Outlet Bar Channel 2002 2,907,311 2,222,800

Calcasieu River Bar Channel, Cameron Parish 2002 9,335,755 7,137,700

Mississippi River Gulf Outlet 2003 2,265,369 1,732,000

Calcasieu River and Pass Bar Channel, Cameron Parish 2003 1,703,736 1,302,600

Atchafalaya River Bar Channel, St. Mary Parish -

Atchafalaya River and Bayous Chene, Boeuf, and Black, LA 2003 11,700,921 8,946,000

Mississippi River Southwest Pass 2003 6,877,593 5,258,300

Mississippi River Gulf Outlet 2004 3,810,582 2,913,400

Atchafalaya River Bar Channel 2004 10,818,708 8,271,500

Calcasieu River and Pass Bar Channel, Cameron Parish 2004 688,766 526,600

Mississippi River Southwest Pass 2004 5,839,474 4,464,600

Mississippi River Gulf Outlet Bar Channel 2005 909,156 695,100

Atchafalaya River Bar Channel 2005 12,811,239 9,794,900

Calcasieu River and Pass Bar Channel 2005 1,683,724 1,287,300

Mississippi River Southwest Pass 2005 6,000,351 4,587,600

Atchafalaya River Bar Channel 2006 8,169,063 6,245,700

Calcasieu River and Pass Bar Channel 2006 1,740,358 1,330,600

Mississippi River Southwest Pass 2006 3,584,829 2,740,800

Mississippi River Southwest Pass 2007 3,004,492 2,297,100

Calcasieu River and Pass Bar Channel 2007 241,840 184,900

Atchafalaya River Bar Channel 2007 14,305,442 10,937,300

Atchafalaya River Bar Channel 2008 9,546,335 7,298,700

Calcasieu River and Pass Bar Channel 2008 364,656 278,800

Mississippi River Southwest Pass 2008 6,890,804 5,268,400

Atchafalaya River Bar Channel 2009 672,417 514,100

Calcasieu River and Pass Bar Channel 2009 1,149,426 878,800

Mississippi River Southwest Pass 2009 5,797,488 4,432,500

Calcasieu River and Pass Bar Channel 2010 829,502 634,200

Mississippi River Southwest Pass 2010 6,070,588 4,641,300

Total 208,396,847 159,330,900

* Dredged material disposed in Ocean Dredged-Material Disposal Site.

Sources: U.S. Dept. of the Army, COE, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010a, and 2010b.
Tables Tables-15

Table 3-13

Corps of Engineers’ Mobile District Maintenance Dredging Activity 

for Federal Navigation Channels in Mississippi, Alabama, and Florida, 2000-2010*

Harbor, Channel, or Waterway Year Volume Dredged

yd3 m3

Mobile Harbor 2001 4,594,174 3,512,500

Pascagoula Harbor 2001 3,200,030 2,446,600

Pascagoula Harbor and Bayou Casotte Extension 2001 294,812 225,400

Mobile Harbor 2002 4,101,600 3,135,900

Gulfport Harbor 2002 943,032 721,000

Pascagoula Harbor 2002 630,301 481,900

Mobile River 2003 2,067,607 1,580,800

Mobile Harbor 2003 1,723,355 1,317,600

Mobile Bay Channel 2003 2,741,725 2,096,200

Mobile Bay 2003 253,350 193,700

Gulfport Bar 2003 128,310 98,100

Pascagoula Bar 2003 123,340 94,300

Pascagoula Navy Channel 2003 558,756 427,200

Gulfport Harbor 2003 542,799 415,000

Bayou Casotte 2003 294,681 225,300

Pascagoula Sound 2003 120,855 92,400

Mobile Harbor 2004 7,849,270 6,001,200

Pascagoula Harbor 2004 1,203,576 920,200

Gulfport Harbor 2004 849,514 649,500

Mobile Harbor 2005 3,224,097 2,465,000

Pensacola Harbor 2005 63,043 48,200

Pascagoula Bar 2005 120,070 91,800

Gulfport Bar 2005 390,031 298,200

Mobile Harbor 2006 2,546,709 1,947,100

Pascagoula Harbor 2006 672,548 514,200

Mobile Harbor 2007 1,952,900 1,493,100

Mobile Harbor Federal Navigation Project 2008 3,725,303 2,848,200

Mobile Harbor 2009 5,980,209 4,572,200

Pascagoula Harbor 2009 152,769 116,800

Gulfport Harbor 2009 4,218,924 3,225,600

Mobile Harbor 2010 4,362,013 3,335,000

Gulfport Harbor 2010 8,486,895 6,488,700

Total 68,116,598 52,078,900

* Dredged material disposed in Ocean Dredged-Material Disposal Site.

Sources: U.S. Dept. of the Army, COE, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010a, and 2010b.
Tables-16 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-1 

Unusual Mortality Event Cetacean Data for the Northern Gulf of Mexico

Cetaceans Stranded Phase of Oil-Spill Response Dates

114 cetaceans stranded Prior to the response phase for the oil 

spill

February 1, 2010-April 29, 2010

122 cetaceans stranded or 

were reported dead offshore

During the initial response phase to 

the oil spill

April 30, 2010-November 2, 2010

850 cetaceans stranded* After the initial response phase ended November 3, 2010-November 24, 

2013**

Note: Numbers are preliminary and may be subject to change. As of February 2, 2014, the unusual mortality 

event involves 1,086 cetacean “strandings” in the northern Gulf of Mexico (USDOC, NMFS, 2014).

* This number includes six dolphins that were killed incidental to fish-related scientific data collection and 

one dolphin that was killed incidental to trawl relocation for a dredging project.

** The initial response phase ended for all four states on November 3, 2010, but then reopened for eastern and 

central Louisiana on December 3, 2010, and closed again on May 25, 2011.

Table 4-2

Economic Significance of Commercial Fishing 2011

State Landings Revenue

(thousand $)1

Sales Impacts

(thousand $)1 Job Impacts1 CFLQ2

Alabama 50,941 499,805 11,011 0.87

Louisiana 333,619 1,801,568 32,818 1.58

Mississippi 30,300 247,106 5,550 ND

Texas 239,082 2,277,959 27,717 0.20

West Florida 164,076 14,250,006 72,341 1.00

Total 818,018 19,076,444 149,437 –

Notes: CFLQ = commercial fishing quotient.

 ND = These data are confidential, thus not disclosable. 1 Landings Revenue, Sales Impacts, and Job Impacts are based on 2011 data. 2 The CFLQ data are based on 2010 data.

Source: USDOC, NMFS, 2013a.
Tables Tables-17

Table 4-3

Angler Trips in the Gulf of Mexico by Location and Mode from 2008 through 2012

State Area 2008 2009 2010 2011 2012 % State Total in 2012

Alabama Shore Ocean (< 3 nmi) 249,893 322,126 447,041 603,546 750,159 32.54%

Shore Inland 452,192 449,470 365,234 598,700 461,221 20.01%

Charter Ocean (<3 nmi) 9,967 9,166 8,860 19,874 15,785 0.68%

Charter Ocean (>3 nmi) 38,046 36,259 17,424 48,616 28,340 1.23%

Charter Inland 7,700 10,656 7,221 6,351 14,536 0.63%

Private/Rental Ocean (<3 nmi) 247,876 131,997 114,816 191,563 137,321 5.96%

Private/Rental Ocean (>3 nmi) 74,074 134,411 69,335 188,994 131,897 5.72%

Private/Rental Inland 624,197 618,502 656,226 825,821 766,027 33.23%

Total 1,703,945 1,712,587 1,686,157 2,483,465 2,305,286

West Florida Shore Ocean (< 9 nmi) 3,076,591 2,688,011 1,610,807 1,982,194 2,199,810 14.88%

Shore Inland 3,704,990 3,793,756 4,034,208 3,862,665 4,016,544 27.18%

Charter Ocean (<9 nmi) 187,810 196,753 159,317 179,880 242,666 1.64%

Charter Ocean (>9 nmi) 255,300 262,005 203,201 236,088 307,121 2.08%

Charter Inland 127,801 113,842 98,440 119,826 149,315 1.01%

Private/Rental Ocean (<9 nmi) 3,624,073 2,605,196 2,257,349 1,901,217 2,087,991 14.13%

Private/Rental Ocean (>9 nmi) 1,242,935 751,869 681,551 500,067 755,470 5.11%

Private/Rental Inland 5,277,665 5,265,888 5,221,323 5,118,740 5,021,267 33.97%

Total 17,497,165 15,677,320 14,266,196 13,900,677 14,780,184

Louisiana Shore Ocean (< 3 nmi) 62,712 38,930 11,664 48,893 152,094 3.68%

Shore Inland 870,042 730,053 717,006 1,073,035 978,657 23.66%

Charter Ocean (<3 nmi) 10,468 3,931 2,762 6,937 3,646 0.09%

Charter Ocean (>3 nmi) 32,805 21,173 8,106 15,742 19,827 0.48%

Charter Inland 135,915 157,692 68,018 90,057 91,192 2.20%

Private/Rental Ocean (<3 nmi) 97,797 81,008 59,347 77,986 116,854 2.82%

Private/Rental Ocean (>3 nmi) 89,859 99,352 11,568 80,952 88,503 2.14%

Private/Rental Inland 3,320,459 2,995,875 2,984,016 3,182,645 2,685,791 64.93%

Total 4,620,057 4,128,014 3,862,487 4,576,247 4,136,564
Tables-18 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-3. Angler Trips in the Gulf of Mexico by Location and Mode from 2008 through 2012 (continued)

State Area 2008 2009 2010 2011 2012 % State Total in 2012

Mississippi Shore Ocean (< 3 nmi) 0 143 0 0 811 0.04%

Shore Inland 359,438 309,612 596,544 760,788 947,075 48.56%

Charter Ocean (<3 nmi) 4,286 2,803 904 3,123 1,628 0.08%

Charter Ocean (>3 nmi) 718 330 949 221 125 0.01%

Charter Inland 8,229 7,656 4,989 7,891 9,738 0.50%

Private/Rental Ocean (<3 nmi) 12,056 16,962 12,419 18,682 4,116 0.21%

Private/Rental Ocean (>3 nmi) 28,007 26,316 4,626 12,974 41,137 2.11%

Private/Rental Inland 555,951 715,505 612,162 811,711 945,819 48.49%

Total 968,685 1,079,327 1,232,593 1,615,390 1,950,449

Gulf Total Shore Ocean (< 3 nmi) 3,389,196 3,049,210 2,069,512 2,634,633 3,102,874 13.39%

Shore Inland 5,386,662 5,282,891 5,712,992 6,295,188 6,403,497 27.63%

Charter Ocean (<3 nmi) 212,531 212,653 171,843 209,814 263,725 1.14%

Charter Ocean (>3 nmi) 326,869 319,767 229,680 300,667 355,413 1.53%

Charter Inland 279,645 289,846 178,668 224,125 264,781 1.14%

Private/Rental Ocean (<3 nmi) 3,981,802 2,835,163 2,443,931 2,189,448 2,346,282 10.13%

Private/Rental Ocean (>3 nmi) 1,434,875 1,011,948 767,080 782,987 1,017,007 4.39%

Private/Rental Inland 9,778,272 9,595,770 9,473,727 9,938,917 9,418,904 40.65%

Total 24,789,852 22,597,248 21,047,433 22,575,779 23,172,483

Notes: This table presents the sum of fishing data from Louisiana, Mississippi, Alabama, and West Florida.

State waters in Florida extend 9 nmi from the coast rather than the typical 3 nmi. 

Source: USDOC, NMFS, 2013b.
Tables Tables-19

Table 4-4

Fish Species Caught by Recreational Anglers from 2008 through 2012

Species/Year 2008 2009 2010 2011 2012

Panel A: Number of Fish

Atlantic Croaker 5,020,732 5,029,701 5,337,312 7,950,146 5,226,056

Black Drum 1,975,432 1,770,479 1,763,633 1,884,447 1,742,449

Blackfin Tuna 137,887 84,978 32,147 53,829 108,196

Cobia 160,155 86,106 62,400 109,388 94,150

Dolphins 640,488 401,891 270,119 456,829 368,565

Gag 4,556,734 2,969,559 2,260,741 1,269,038 1,125,765

Gray Snapper 7,316,720 4,446,255 2,451,867 2,800,767 4,525,563

Great Amberjack 248,910 212,229 382,672 250,954 167,585

King mackerel 374,338 673,530 291,065 244,812 367,142

Little Tuny 203,560 168,356 140,474 201,761 336,497

Pinfishes 16,112,529 9,876,807 10,415,589 8,851,759 13,360,140

Red Drum 10,310,311 8,132,874 9,718,538 9,992,160 9,018,589

Red Grouper 3,105,159 3,172,238 2,242,746 2,009,532 2,010,089

Red Snapper 2,789,675 2,941,448 1,769,536 2,041,512 2,015,848

Sand Seatrout 5,335,003 6,632,448 6,329,040 8,268,113 7,352,122

Sheepshead 3,055,781 2,911,901 2,884,114 3,849,215 2,968,888

Southern Flounder 594,926 837,108 991,760 987,796 1,050,315

Southern Kingfish 1,590,202 1,417,523 1,450,408 1,163,302 835,582

Spanish Mackerel 3,938,013 3,138,754 4,040,757 3,475,966 3,278,437

Spotted Seatrout 35,141,138 30,700,217 24,703,470 32,700,839 32,997,778

Striped Mullet 1,405,717 967,398 1,791,862 2,214,375 2,559,404

White Grunt 3,721,050 2,285,007 2,494,075 2,852,807 3,405,536

Panel B: Pounds

Atlantic Croaker 746,737 417,298 529,427 816,562 608,874

Black Drum 3,329,225 2,720,006 2,433,846 2,487,203 3,195,532

Blackfin Tuna 854,254 1,225,530 276,947 415,204 1,450,081

Cobia 797,585 510,151 483,465 1,132,455 876,210

Dolphins 1,758,506 2,114,876 685,194 1,295,453 1,435,715

Gag 3,250,623 1,485,256 1,630,999 665,580 1,018,029

Gray Snapper 2,016,456 1,525,684 882,715 1,250,520 1,506,738

Great Amberjack 1,407,076 1,523,734 1,483,609 946,467 1,326,805

King Mackerel 1,804,192 3,677,465 1,808,493 1,679,476 2,501,381

Little Tuny 439,608 517,938 418,973 455,612 1,195,713

Pinfishes 2,029,509 801,445 2,028,069 1,574,080 1,172,020

Red Drum 14,496,283 11,773,528 13,509,248 15,340,878 11,964,241

Red Grouper 879,028 981,966 762,208 640,002 1,784,678

Red Snapper 2,806,925 3,648,516 1,655,857 3,486,486 4,446,272
Tables-20 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-4. Fish Species Caught by Recreational Anglers from 2008 through 2012 (continued)

Species/Year 2008 2009 2010 2011 2012

Panel B: Pounds

Sand Seatrout 1,880,159 2,308,490 2,579,227 3,412,201 2,545,250

Sheepshead 4,415,722 3,904,616 3,296,696 6,990,784 3,816,260

Southern Flounder 687,368 910,196 1,104,725 1,120,655 1,039,927

Southern Kingfish 553,205 638,419 568,799 390,627 292,906

Spanish Mackerel 2,943,974 2,072,995 2,546,029 2,132,604 2,677,171

Spotted Seatrout 16,156,781 15,393,934 12,259,023 17,924,543 16,211,441

Striped Mullet 1,614,209 899,038 2,674,277 2,055,630 1,981,230

White Grunt 1,131,685 1,030,272 930,723 1,266,126 1,407,171

Source: USDOC, NMFS, 2013c.

Table 4-5

Economic Impact of Recreational Fishing in the Gulf of Mexico in 2011

Expenditures Sales Value Added Employment

Alabama 856,334 797,280 410,222 8,177

West Florida 5,494,694 4,881,831 2,653,677 47,047

Mississippi 149,129 145,769 60,735 1,181

Louisiana 1,879,471 1,602,913 806,349 17,764

Texas 1,402,516 1,853,361 952,284 15,150

Total 9,782,144 9,281,154 4,883,267 89,319

Note: Expenditures, Sales, and Value Added are presented in thousands of dollars.

Source: USDOC, NMFS, 2013a.
Tables Tables-21 

Table 4-6

Employment in the Leisure/Hospitality Industry in Selected Geographic Regions

Region 2008 2009 2010 2011 2012

Panel A: EIA

TX-1 54,551 53,772 54,750 56,753 60,670

TX-2 16,883 16,718 16,934 18,197 19,915

TX-3 240,231 240,425 244,821 253,071 267,390

LA-1 14,295 14,214 13,979 14,489 14,635

LA-2 21,364 20,675 20,618 21,345 22,137

LA-3 46,037 44,414 44,796 47,121 48,930

LA-4 68,605 68,161 72,757 76,552 78,978

MS-1 27,702 26,904 26,981 27,826 28,409

AL-1 26,516 25,872 26,925 27,300 28,307

FL-1 40,001 41,002 42,550 45,160 46,720

FL-2 22,502 21,689 22,111 22,466 23,579

FL-3 146,368 142,302 145,324 148,103 158,030

FL-4 283,359 279,839 289,247 304,093 319,912

TX EIA total 311,665 310,915 316,505 328,021 347,975

LA EIA total 150,301 147,464 152,150 159,507 164,680

MS EIA total 27,702 26,904 26,981 27,826 28,409

AL EIA total 26,516 25,872 26,925 27,300 28,307

FL EIA total 492,230 484,832 499,232 519,822 548,241

EIA total 1,008,414 995,987 1,021,793 1,062,476 1,117,612

Panel B: Coastal

TX 67,087 67,818 68,260 71,041 75,895

LA 45,545 45,418 49,432 51,742 53,802

MS 25,575 25,055 25,186 25,900 26,353

AL 24,319 23,825 24,816 25,145 25,941

FL 386,892 383,959 396,485 415,379 437,509

Coastal total 549,418 546,075 564,179 589,207 619,500

Panel C: Statewide

TX 995,445 982,840 1,006,277 1,039,839 1,094,916

LA 194,905 190,589 194,387 202,704 208,284

MS 121,033 115,868 116,204 117,874 120,472

AL 168,413 165,953 165,230 166,671 170,854

FL 922,534 896,383 929,448 962,616 1,011,874

State total 2,402,330 2,351,633 2,411,546 2,489,704 2,606,400

(1) Economic Impact Areas are defined in Figure 4-20 of the 2012-2017 WPA/CPA Multisale EIS.

(2) The Coastal category refers to counties within EIA’s that are directly along the coast of the U.S.

(3) The Statewide category refers to the number of employees within the borders of the entire state.

(4) The leisure/hospitality industry is defined according to the North American Industrial Classification 

System (NAICS). 

(5) The employment figure for any given year corresponds to the total number of employees in 

December of that year.

Source: U.S. Dept. of Labor, Bureau of Labor Statistics, 2013. 
Tables-22 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-7

Peak Population Projected from Cumulative OCS Programs as a Percent of Total Population

EIA 

Low Case High Case

Peak 

Annual Peak Year Baseline in Peak Year Percent Peak Annual Peak Year Baseline in Peak Year Percent

Texas (TX)

TX-1 16,250 2030 2,453,620 0.66% 25,369 2031 2,485,990 1.02%

TX-2 6,620 2031 854,250 0.77% 10,759 2031 854,250 1.26%

TX-3 137,573 2030 8,927,830 1.54% 203,022 2031 9,061,710 2.24%

Louisiana (LA)

LA-1 8,959 2030 410,370 2.18% 14,763 2031 413,690 3.57%

LA-2 25,960 2030 792,830 3.27% 40,748 2031 803,500 5.07%

LA-3 33,867 2030 1,375,330 2.46% 54,048 2031 1,387,050 3.90%

LA-4 17,490 2030 1,389,220 1.26% 27,980 2031 1,396,050 2.00%

Florida (FL)

FL-1 4,773 2031 1,119,900 0.43% 7,726 2031 1,119,900 0.69%

FL-2 9,402 2031 835,070 1.13% 15,307 2031 835,070 1.83%

FL-3 8,265 2031 4,857,480 0.17% 13,509 2031 4,857,480 0.28%

FL-4 5,916 2031 8,090,210 0.07% 9,658 2031 8,090,210 0.12%

Alabama (AL)

AL-1 11,251 2030 848,420 1.33% 18,405 2031 854,710 2.15%

Mississippi (MS)

MS-1 8,726 2030 546,670 1.60% 14,116 2031 549,830 2.57%

Sources: Peak employment output from BOEM’s economic impact model (MAG-PLAN)

Baseline employment projections based on Woods & Poole Economics, Inc. (2013).
Table 4-8 Baseline Population Projections (in thousands) by Economic Impact Area Model Year Calendar Year TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 

2010 1,799.29 626.91 6,202.21 346.02 585.06 1,142.41 1,242.69 482.30 725.87 882.80 659.96 3,62

 2011 1,827.28 633.41 6,309.03 346.51 588.41 1,147.53 1,260.01 486.36 727.78 889.79 661.80 3,66 2012 1,858.83 644.11 6,442.79 349.64 598.63 1,158.87 1,265.95 489.21 733.64 900.72 670.02 3,72 2013 1,890.78 654.92 6,577.78 352.85 608.98 1,170.43 1,272.16 492.17 739.67 911.84 678.38 3,77 2014 1,923.07 665.83 6,713.83 356.11 619.45 1,182.18 1,278.59 495.21 745.81 923.11 686.86 3,83 2015 1,955.52 676.78 6,850.35 359.40 629.98 1,194.01 1,285.13 498.29 752.02 934.45 695.39 3,89 2016 1,988.13 687.77 6,987.28 362.72 640.58 1,205.90 1,291.75 501.40 758.28 945.85 703.97 3,95 2017 2,020.90 698.81 7,124.69 366.07 651.23 1,217.87 1,298.48 504.55 764.59 957.31 712.59 4,01 2018 2,053.85 709.89 7,262.62 369.43 661.96 1,229.92 1,305.31 507.74 770.96 968.84 721.28 4,07 2019 2,086.93 721.00 7,400.96 372.82 672.73 1,242.03 1,312.22 510.96 777.37 980.44 730.00 4,13 2020 2,120.07 732.12 7,539.40 376.22 683.54 1,254.14 1,319.15 514.19 783.79 992.04 738.73 4,19 2021 2,152.43 742.96 7,673.56 379.58 694.11 1,266.08 1,326.11 517.41 790.17 1,003.45 747.33 4,25 2022 2,185.28 753.96 7,810.10 382.98 704.85 1,278.14 1,333.11 520.65 796.60 1,015.00 756.02 4,31 2023 2,218.63 765.12 7,949.07 386.40 715.75 1,290.31 1,340.14 523.91 803.08 1,026.67 764.81 4,37 2024 2,252.49 776.44 8,090.52 389.85 726.83 1,302.60 1,347.21 527.19 809.61 1,038.48 773.71 4,43 2025 2,286.87 787.94 8,234.48 393.34 738.07 1,315.00 1,354.31 530.49 816.20 1,050.43 782.71 4,49 2026 2,319.29 798.75 8,368.70 396.69 748.71 1,326.85 1,361.22 533.69 822.55 1,061.81 791.29 4,55 2027 2,352.16 809.70 8,505.11 400.06 759.50 1,338.81 1,368.17 536.91 828.94 1,073.32 799.96 4,61 2028 2,385.51 820.81 8,643.74 403.47 770.45 1,350.88 1,375.15 540.14 835.38 1,084.95 808.72 4,67 2029 2,419.33 832.08 8,784.64 406.90 781.56 1,363.05 1,382.17 543.40 841.88 1,096.70 817.59 4,73 2030 2,453.62 843.49 8,927.83 410.37 792.83 1,375.33 1,389.22 546.67 848.42 1,108.59 826.55 4,79 2031 2,485.99 854.25 9,061.71 413.69 803.50 1,387.05 1,396.05 549.83 854.71 1,119.90 835.07 4,85 2032 2,518.78 865.14 9,197.61 417.03 814.31 1,398.87 1,402.90 553.01 861.04 1,131.33 843.69 4,91 2033 2,552.00 876.17 9,335.54 420.41 825.27 1,410.78 1,409.79 556.20 867.42 1,142.87 852.40 4,97 2034 2,585.67 887.34 9,475.53 423.81 836.37 1,422.80 1,416.71 559.41 873.84 1,154.53 861.20 5,03 2035 2,619.77 898.65 9,617.63 427.24 847.63 1,434.92 1,423.67 562.64 880.32 1,166.31 870.08 5,09 2036 2,652.33 909.44 9,752.11 430.57 858.40 1,446.66 1,430.55 565.82 886.64 1,177.68 878.66 5,15 2037 2,685.30 920.36 9,888.47 433.94 869.31 1,458.50 1,437.47 569.02 893.01 1,189.15 887.32 5,21 2038 2,718.67 931.41 10,026.73 437.32 880.36 1,470.43 1,444.43 572.23 899.42 1,200.74 896.06 5,27
Tables-24 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-8. Baseline Population Projections (in thousands) by Economic Impact Area (continued)

Model

Year 

Calendar 

Year TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 Total 

2039 2,752.46 942.59 10,166.93 440.74 891.55 1,482.46 1,451.41 575.46 905.88 1,212.44 904.89 5,336.57 8,819.54 35,882.93

2040 2,786.67 953.91 10,309.09 444.18 902.89 1,494.59 1,458.44 578.72 912.38 1,224.25 913.81 5,397.92 8,912.76 36,289.59

2041 2,821.31 965.36 10,453.24 447.65 914.36 1,506.82 1,465.49 581.99 918.93 1,236.18 922.81 5,459.96 9,006.96 36,701.06

2042 2,856.37 976.95 10,599.40 451.15 925.99 1,519.14 1,472.58 585.27 925.53 1,248.23 931.90 5,522.72 9,102.17 37,117.41

2043 2,891.87 988.68 10,747.60 454.67 937.76 1,531.57 1,479.70 588.58 932.18 1,260.39 941.09 5,586.20 9,198.37 37,538.68

2044 2,927.82 1,000.55 10,897.88 458.22 949.68 1,544.10 1,486.86 591.91 938.87 1,272.67 950.36 5,650.41 9,295.60 37,964.94

2045 2,964.20 1,012.57 11,050.26 461.80 961.75 1,556.73 1,494.05 595.25 945.61 1,285.07 959.73 5,715.36 9,393.85 38,396.25

2046 3,001.05 1,024.72 11,204.77 465.41 973.98 1,569.47 1,501.28 598.61 952.40 1,297.59 969.18 5,781.06 9,493.14 38,832.67

2047 3,038.35 1,037.03 11,361.44 469.05 986.36 1,582.31 1,508.54 602.00 959.24 1,310.24 978.73 5,847.51 9,593.49 39,274.27

2048 3,076.11 1,049.48 11,520.30 472.71 998.90 1,595.26 1,515.84 605.40 966.13 1,323.00 988.38 5,914.72 9,694.89 39,721.11

2049 3,114.34 1,062.08 11,681.38 476.40 1,011.59 1,608.31 1,523.17 608.82 973.07 1,335.89 998.12 5,982.71 9,797.36 40,173.24

2050 3,153.05 1,074.83 11,844.72 480.12 1,024.45 1,621.46 1,530.54 612.26 980.06 1,348.91 1,007.95 6,051.48 9,900.92 40,630.75

2051 3,192.24 1,087.73 12,010.34 483.87 1,037.47 1,634.73 1,537.94 615.72 987.09 1,362.05 1,017.89 6,121.04 10,005.57 41,093.69

2052 3,231.91 1,100.79 12,178.27 487.65 1,050.66 1,648.10 1,545.38 619.19 994.18 1,375.33 1,027.92 6,191.40 10,111.33 41,562.12

2053 3,272.08 1,114.01 12,348.55 491.46 1,064.02 1,661.59 1,552.86 622.69 1,001.32 1,388.73 1,038.05 6,262.57 10,218.20 42,036.12

2054 3,312.75 1,127.39 12,521.21 495.30 1,077.54 1,675.18 1,560.37 626.21 1,008.51 1,402.26 1,048.28 6,334.55 10,326.21 42,515.76

2055 3,353.92 1,140.92 12,696.29 499.17 1,091.24 1,688.89 1,567.92 629.75 1,015.75 1,415.92 1,058.61 6,407.36 10,435.35 43,001.10

2012/2051 Growth 1.40% 1.35% 1.61% 0.84% 1.42% 0.89% 0.50% 0.59% 0.76% 1.07% 1.08% 1.28% 1.17% 1.26%

Notes: Actual Woods & Poole data for 2010 through 2020, 2025, 2030, 2035, and 2040. 

Missing estimates through 2040 calculated using average annual growth rate for the 5-year period; projections after 2040 calculated using the average annual growth rate from 2035 to 2040.

Source: Woods & Poole Economics, Inc., 2013.
Tables Tables-25

Table 4-9

Demographic and Employment Baseline Projections for Economic Impact Area AL-1 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 692.65 725.87 727.78 733.64 739.67 745.81 752.02 777.37 816.20 848.42 912.38

Age Under 19 Years 28.1% 27.1% 26.7% 26.6% 26.5% 26.4% 26.3% 26.2% 25.9% 25.5% 24.6%

Age 20 to 34 18.7% 18.6% 18.8% 18.8% 18.7% 18.6% 18.4% 17.6% 16.7% 16.5% 17.0%

Age 35 to 49 21.3% 19.7% 19.3% 19.0% 18.8% 18.6% 18.5% 18.5% 18.6% 18.5% 17.4%

Age 50 to 64 18.3% 20.1% 20.4% 20.5% 20.6% 20.6% 20.6% 20.1% 18.6% 17.8% 18.5%

Age 65 and over 13.5% 14.4% 14.7% 15.1% 15.5% 15.8% 16.2% 17.6% 20.2% 21.8% 22.6%

Median Age of Population (years) 38.2 39.9 40.2 40.5 40.8 41.0 41.1 41.8 43.0 43.8 45.0

White Population (in thousands) 66.2% 65.2% 65.0% 65.0% 64.9% 64.8% 64.8% 64.4% 63.9% 63.3% 62.4%

Black Population (in thousands) 29.6% 29.6% 29.6% 29.6% 29.5% 29.5% 29.5% 29.4% 29.4% 29.3% 29.1%

Native American Population (in thousands) 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2%

Asian and Pacific Islander Population (in thousands) 1.2% 1.4% 1.4% 1.5% 1.5% 1.5% 1.5% 1.6% 1.7% 1.9% 2.0%

Hispanic or Latino Population (in thousands) 1.9% 2.7% 2.8% 2.9% 3.0% 3.1% 3.1% 3.4% 3.9% 4.3% 5.3%

Male Population (in thousands) 48.3% 48.4% 48.4% 48.4% 48.4% 48.4% 48.4% 48.5% 48.5% 48.5% 48.4%

Total Employment (in thousands of jobs) 363.84 373.38 378.73 379.89 385.02 390.21 395.45 417.11 451.70 482.56 550.51

Farm Employment 1.4% 1.5% 1.4% 1.4% 1.4% 1.4% 1.3% 1.3% 1.2% 1.1% 1.0%

Forestry, Fishing, Related Activities 1.0% 0.9% 0.9% 1.0% 1.0% 1.0% 1.0% 0.9% 0.9% 0.9% 0.8%

Mining 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

Utilities 0.4% 0.4% 0.4% 0.5% 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3%

Construction 8.5% 7.6% 7.2% 7.4% 7.3% 7.3% 7.2% 7.0% 6.8% 6.5% 6.0%

Manufacturing 8.7% 7.2% 7.4% 7.6% 7.5% 7.3% 7.1% 6.6% 5.8% 5.1% 4.0%

Wholesale Trade 3.5% 3.1% 2.9% 2.8% 2.8% 2.8% 2.7% 2.7% 2.5% 2.4% 2.2%

Retail Trade 12.4% 11.9% 11.9% 12.1% 12.0% 12.0% 11.9% 11.8% 11.5% 11.2% 10.6%

Transportation and Warehousing 3.7% 3.6% 3.6% 3.6% 3.5% 3.5% 3.5% 3.4% 3.3% 3.1% 2.9%

Information Employment 1.3% 0.9% 0.9% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7%

Finance and Insurance 3.4% 4.0% 4.1% 3.9% 3.9% 3.9% 3.9% 3.8% 3.7% 3.7% 3.5%

Real Estate/Rental and Lease 4.4% 5.0% 5.0% 4.7% 4.7% 4.7% 4.7% 4.7% 4.7% 4.7% 4.7%

Professional and Technical Services 4.4% 4.5% 4.5% 4.6% 4.6% 4.6% 4.6% 4.7% 4.9% 5.0% 5.2%

Management 0.2% 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.5% 0.5% 0.6%

Administrative and Waste Services 6.4% 7.0% 7.3% 7.5% 7.6% 7.7% 7.8% 8.1% 8.5% 8.9% 9.7%

Educational Services 1.4% 1.8% 1.9% 2.0% 2.0% 2.1% 2.1% 2.2% 2.4% 2.6% 2.9%
Tables-26 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-9. Demographic and Employment Baseline Projections for Economic Impact Area AL-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 8.5% 9.4% 9.4% 9.3% 9.4% 9.5% 9.7% 10.1% 10.8% 11.4% 12.5%

Arts, Entertainment, and Recreation 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.4% 1.4%

Accommodation and Food Services 6.8% 7.3% 7.5% 7.8% 7.9% 7.9% 8.0% 8.3% 8.8% 9.2% 10.0%

Other Services, Except Public Administration 7.7% 8.0% 8.1% 8.0% 8.0% 8.1% 8.2% 8.5% 8.9% 9.2% 9.8%

Federal Civilian Government 0.9% 1.0% 1.0% 1.0% 1.0% 1.0% 0.9% 0.9% 0.8% 0.7% 0.6%

Federal Military 1.3% 1.2% 1.2% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 0.9% 0.8%

State and Local Government 12.0% 11.6% 11.3% 10.9% 10.9% 10.8% 10.8% 10.5% 10.2% 9.9% 9.2%

Total Earnings (in millions of 2005 dollars) 12,929.16 13,560.46 13,587.24 13,806.61 14,074.10 14,370.28 14,672.46 15,943.93 18,055.24 20,023.71 24,628.20

Farm 0.8% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3%

Forestry, Fishing, Related Activities 1.0% 1.0% 1.0% 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.8%

Mining 0.4% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7%

Utilities 1.0% 1.0% 1.0% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 1.0% 0.9%

Construction 8.9% 8.7% 8.3% 8.5% 8.5% 8.4% 8.3% 7.9% 7.3% 6.9% 6.0%

Manufacturing 13.6% 12.6% 13.3% 14.3% 14.3% 14.1% 14.0% 13.3% 12.4% 11.6% 10.0%

Wholesale Trade 5.1% 4.7% 4.4% 4.2% 4.2% 4.2% 4.2% 4.1% 4.0% 3.9% 3.7%

Retail Trade 8.9% 8.2% 8.2% 8.2% 8.2% 8.1% 8.0% 7.6% 7.1% 6.7% 5.9%

Transportation and Warehousing 4.8% 5.1% 5.2% 5.3% 5.2% 5.2% 5.1% 5.0% 4.7% 4.5% 4.0%

Information 1.6% 1.2% 1.2% 1.1% 1.2% 1.2% 1.2% 1.2% 1.2% 1.3% 1.3%

Finance and Insurance 4.9% 4.4% 4.3% 3.9% 3.9% 3.9% 3.9% 3.9% 3.8% 3.8% 3.7%

Real Estate/Rental and Lease 2.3% 1.8% 1.8% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7%

Professional and Technical Services 5.5% 5.8% 5.9% 6.0% 6.1% 6.1% 6.2% 6.5% 6.9% 7.2% 7.9%

Management 0.3% 0.5% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% 0.9% 1.0% 1.4%

Administrative and Waste Services 3.7% 4.3% 4.5% 4.7% 4.8% 4.8% 4.9% 5.2% 5.6% 6.0% 6.8%

Educational Services 0.9% 1.0% 1.1% 1.2% 1.2% 1.2% 1.2% 1.3% 1.5% 1.6% 1.9%

Health Care and Social Assistance 9.8% 10.8% 10.5% 10.3% 10.4% 10.6% 10.7% 11.4% 12.3% 13.1% 14.8%

Arts, Entertainment, and Recreation 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5%

Accommodation and Food Services 3.2% 3.5% 3.6% 3.7% 3.8% 3.8% 3.8% 4.0% 4.3% 4.5% 4.9%

Other Services, Except Public Administration 4.8% 5.0% 5.0% 5.0% 5.0% 5.1% 5.1% 5.3% 5.5% 5.7% 6.2%

Federal Civilian Government 2.2% 2.4% 2.4% 2.4% 2.3% 2.3% 2.3% 2.3% 2.2% 2.1% 2.0%

Federal Military 1.8% 1.8% 1.7% 1.6% 1.4% 1.4% 1.4% 1.4% 1.5% 1.5% 1.5%

State and Local Government 13.8% 14.8% 14.3% 13.8% 13.8% 13.8% 13.8% 13.7% 13.6% 13.5% 13.2%

Total Personal Income per Capita (in 2005 dollars) 26,923 28,669 29,148 29,334 29,496 29,782 30,134 31,910 35,178 38,384 46,143

Woods & Poole Economics Wealth Index (U.S. = 100) 68.7 72.3 71.7 71.7 71.6 71.7 71.8 72.2 72.7 72.9 73.3

Persons per Household (in number of people) 2.5 2.6 2.6 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Tables Tables-27

Table 4-9. Demographic and Employment Baseline Projections for Economic Impact Area AL-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Mean Household Total Personal Income (in 2005 dollars) 68,478 73,643 74,608 74,670 74,691 75,003 75,510 79,057 87,161 95,764 116,991

Number of Households (in thousands) 272.33 282.58 284.33 288.21 292.10 296.14 300.12 313.77 329.42 340.07 359.86

Income <$10,000 (thousands of households, 2000$) 13.4% 11.9% 11.7% 11.5% 11.3% 11.1% 10.9% 9.9% 8.2% 7.0% 5.0%

Income $10,000 to $19,999 14.6% 13.1% 12.9% 12.7% 12.6% 12.4% 12.2% 11.1% 9.3% 8.0% 5.8%

Income $20,000 to $29,999 13.1% 11.9% 11.7% 11.5% 11.4% 11.2% 11.1% 10.2% 8.5% 7.4% 5.3%

Income $30,000 to $44,999 18.8% 18.4% 18.2% 18.1% 18.0% 17.8% 17.6% 16.4% 14.0% 12.1% 8.7%

Income $45,000 to $59,999 14.8% 16.4% 16.7% 16.9% 17.1% 17.3% 17.5% 18.7% 19.5% 18.5% 13.8%

Income $60,000 to $74,999 9.5% 10.6% 10.8% 11.0% 11.1% 11.3% 11.5% 12.6% 15.1% 17.4% 19.3%

Income $75,000 to $99,999 8.3% 9.3% 9.5% 9.6% 9.8% 9.9% 10.1% 11.1% 13.3% 15.5% 21.9%

Income $100,000 or more 7.5% 8.4% 8.6% 8.7% 8.8% 9.0% 9.1% 10.0% 12.1% 14.2% 20.2%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; persons per household calculated using total population/number of households for the EIA

Source: Woods & Poole Economics, Inc., 2013.
Tables-28 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-10

Demographic and Employment Baseline Projections for Economic Impact Area FL-1 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 861.80 882.80 889.79 900.72 911.84 923.11 934.45 980.44 1,050.43 1,108.59 1,224.25

Age Under 19 Years 26.1% 25.0% 24.5% 24.3% 24.2% 24.2% 24.1% 24.3% 24.5% 24.3% 23.6%

Age 20 to 34 20.1% 20.5% 20.9% 21.0% 21.1% 21.1% 21.0% 19.9% 18.1% 17.5% 18.7%

Age 35 to 49 22.3% 20.1% 19.5% 18.9% 18.4% 18.0% 17.7% 17.8% 19.0% 19.6% 17.3%

Age 50 to 64 18.2% 20.1% 20.6% 20.7% 20.8% 20.9% 21.0% 20.4% 18.2% 16.3% 17.9%

Age 65 and over 13.3% 14.3% 14.6% 15.0% 15.5% 15.8% 16.2% 17.5% 20.1% 22.2% 22.6%

Median Age of Population (years) 39.5 40.3 40.5 40.6 40.7 40.8 40.8 40.9 41.6 42.3 42.6

White Population (in thousands) 79.1% 77.2% 76.8% 76.6% 76.4% 76.2% 76.0% 75.2% 73.9% 72.7% 70.3%

Black Population (in thousands) 13.5% 14.0% 14.2% 14.2% 14.2% 14.3% 14.3% 14.4% 14.6% 14.8% 15.0%

Native American Population (in thousands) 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7% 0.7% 0.7% 0.6% 0.5%

Asian and Pacific Islander Population (in thousands) 2.5% 2.8% 2.8% 2.9% 2.9% 2.9% 2.9% 3.0% 3.1% 3.2% 3.3%

Hispanic or Latino Population (in thousands) 4.0% 5.1% 5.4% 5.5% 5.7% 5.9% 6.0% 6.6% 7.7% 8.6% 10.8%

Male Population (in thousands) 50.1% 50.2% 50.2% 50.2% 50.3% 50.3% 50.3% 50.4% 50.7% 50.8% 51.1%

Total Employment (in thousands of jobs) 487.45 473.21 483.35 489.04 495.84 502.71 509.67 538.36 584.04 624.72 713.84

Farm Employment 0.5% 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4%

Forestry, Fishing, Related Activities 0.5% 0.5% 0.5% 0.6% 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5%

Mining 0.2% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2%

Utilities 0.3% 0.5% 0.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7%

Construction 9.0% 6.1% 6.1% 6.3% 6.2% 6.2% 6.2% 6.0% 5.8% 5.6% 5.2%

Manufacturing 3.4% 3.0% 3.0% 3.1% 3.0% 2.9% 2.9% 2.6% 2.3% 2.1% 1.6%

Wholesale Trade 2.6% 2.2% 2.1% 2.1% 2.1% 2.1% 2.1% 2.0% 1.9% 1.9% 1.7%

Retail Trade 12.0% 11.3% 11.1% 11.1% 11.1% 11.0% 11.0% 10.9% 10.6% 10.4% 10.0%

Transportation and Warehousing 1.8% 1.7% 1.7% 1.7% 1.7% 1.6% 1.6% 1.6% 1.6% 1.5% 1.4%

Information Employment 1.9% 1.5% 1.5% 1.5% 1.5% 1.4% 1.4% 1.4% 1.4% 1.3% 1.2%

Finance and Insurance 3.6% 4.4% 4.5% 4.2% 4.3% 4.3% 4.3% 4.4% 4.5% 4.7% 4.8%

Real Estate/Rental and Lease 5.5% 5.4% 5.4% 5.3% 5.3% 5.3% 5.3% 5.4% 5.4% 5.5% 5.5%

Professional and Technical Services 5.2% 5.8% 6.0% 6.1% 6.2% 6.3% 6.4% 6.8% 7.3% 7.8% 8.8%

Management 0.5% 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

Administrative and Waste Services 7.0% 6.6% 6.5% 6.4% 6.5% 6.5% 6.5% 6.7% 6.9% 7.1% 7.5%

Educational Services 1.0% 1.3% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4%
Tables Tables-29

Table 4-10. Demographic and Employment Baseline Projections for Economic Impact Area FL-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 8.9% 10.2% 10.4% 10.5% 10.7% 10.8% 10.9% 11.4% 12.1% 12.7% 14.0%

Arts, Entertainment, and Recreation 1.7% 2.0% 2.0% 2.1% 2.1% 2.2% 2.2% 2.3% 2.4% 2.5% 2.7%

Accommodation and Food Services 8.8% 9.4% 9.5% 9.5% 9.5% 9.6% 9.6% 9.6% 9.6% 9.6% 9.5%

Other Services, Except Public Administration 6.2% 6.2% 6.2% 6.2% 6.3% 6.3% 6.3% 6.5% 6.6% 6.8% 7.0%

Federal Civilian Government 3.5% 4.0% 4.0% 4.1% 4.0% 4.0% 3.9% 3.8% 3.5% 3.3% 2.9%

Federal Military 6.9% 7.0% 6.9% 6.8% 6.7% 6.6% 6.6% 6.2% 5.8% 5.4% 4.8%

State and Local Government 9.1% 9.6% 9.4% 9.2% 9.1% 9.1% 9.0% 8.8% 8.4% 8.1% 7.5%

Total Earnings (in millions of 2005 dollars) 19,144.97 18,884.77 19,048.20 19,025.90 19,536.31 19,997.79 20,469.77 22,467.72 25,823.44 28,988.08 36,494.20

Farm 0.1% 0.2% 0.2% 0.2% 0.2% 0.2% 0.1% 0.1% 0.1% 0.1% 0.1%

Forestry, Fishing, Related Activities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Mining 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1%

Utilities 0.5% 0.9% 1.1% 1.3% 1.1% 1.1% 1.2% 1.2% 1.4% 1.5% 1.7%

Construction 8.1% 5.5% 5.5% 5.8% 5.7% 5.6% 5.5% 5.2% 4.8% 4.5% 3.8%

Manufacturing 4.8% 4.2% 4.1% 4.1% 4.1% 4.0% 3.9% 3.7% 3.3% 3.0% 2.5%

Wholesale Trade 3.0% 2.7% 2.6% 2.6% 2.6% 2.6% 2.6% 2.5% 2.5% 2.4% 2.3%

Retail Trade 7.9% 7.0% 7.0% 7.1% 7.0% 6.9% 6.8% 6.5% 6.0% 5.6% 4.9%

Transportation and Warehousing 1.8% 1.7% 1.7% 1.7% 1.6% 1.6% 1.6% 1.5% 1.4% 1.4% 1.2%

Information 2.4% 1.9% 1.9% 1.8% 1.8% 1.8% 1.8% 1.8% 1.9% 1.9% 1.9%

Finance and Insurance 3.9% 3.8% 3.8% 3.6% 3.6% 3.7% 3.7% 3.8% 3.9% 4.0% 4.2%

Real Estate/Rental and Lease 3.1% 1.8% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9%

Professional and Technical Services 6.6% 7.5% 7.7% 7.8% 7.9% 8.1% 8.2% 8.7% 9.6% 10.3% 11.9%

Management 0.8% 0.4% 0.3% 0.3% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% 0.7%

Administrative and Waste Services 4.5% 4.1% 4.1% 4.0% 4.1% 4.1% 4.2% 4.3% 4.5% 4.7% 5.0%

Educational Services 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% 0.8% 0.8% 0.8% 0.8%

Health Care and Social Assistance 10.0% 11.5% 11.6% 11.8% 11.9% 12.0% 12.2% 12.7% 13.6% 14.3% 15.8%

Arts, Entertainment, and Recreation 0.6% 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% 0.8% 0.8%

Accommodation and Food Services 4.6% 4.6% 4.6% 4.6% 4.6% 4.6% 4.6% 4.6% 4.6% 4.6% 4.5%

Other Services, Except Public Administration 4.4% 4.0% 4.0% 4.1% 4.1% 4.1% 4.1% 4.2% 4.2% 4.3% 4.3%

Federal Civilian Government 6.8% 8.2% 8.1% 8.1% 8.1% 8.0% 8.0% 7.9% 7.6% 7.4% 7.0%

Federal Military 14.5% 17.1% 16.9% 16.7% 16.7% 16.7% 16.6% 16.4% 16.1% 15.9% 15.3%

State and Local Government 10.5% 11.3% 11.0% 10.6% 10.5% 10.5% 10.5% 10.3% 10.0% 9.7% 9.2%

Total Personal Income per Capita (in 2005 dollars) 31,073 32,385 32,979 32,765 32,929 33,163 33,486 35,242 38,588 41,917 50,041

Woods & Poole Economics Wealth Index (U.S. = 100) 85.9 86.8 86.4 85.5 85.5 85.4 85.3 85.2 85.2 85.2 85.3

Persons per Household (in number of people) 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Tables-30 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-10. Demographic and Employment Baseline Projections for Economic Impact Area FL-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Mean Household Total Personal Income (in 2005 dollars) 78,593 82,502 83,713 82,744 82,738 82,886 83,286 86,728 95,078 104,101 126,566

Number of Households (in thousands) 340.73 346.54 350.54 356.67 362.90 369.34 375.70 398.40 426.33 446.38 484.04

Income <$10,000 (thousands of households, 2000$) 8.6% 7.7% 7.6% 7.5% 7.4% 7.3% 7.2% 6.6% 5.5% 4.7% 3.4%

Income $10,000 to $19,999 12.3% 11.1% 10.8% 10.8% 10.6% 10.5% 10.3% 9.4% 7.9% 6.8% 4.9%

Income $20,000 to $29,999 13.7% 12.4% 12.1% 12.0% 11.8% 11.7% 11.5% 10.5% 8.8% 7.6% 5.5%

Income $30,000 to $44,999 19.6% 18.3% 17.9% 17.8% 17.6% 17.3% 17.1% 15.6% 13.1% 11.3% 8.2%

Income $45,000 to $59,999 16.6% 18.1% 18.4% 18.5% 18.7% 18.8% 19.0% 19.6% 18.8% 16.7% 12.2%

Income $60,000 to $74,999 11.3% 12.5% 12.8% 13.0% 13.1% 13.3% 13.5% 14.8% 17.7% 20.1% 20.2%

Income $75,000 to $99,999 9.3% 10.2% 10.5% 10.6% 10.7% 10.9% 11.0% 12.1% 14.5% 16.8% 23.4%

Income $100,000 or more 8.7% 9.6% 9.9% 10.0% 10.1% 10.2% 10.4% 11.4% 13.7% 15.9% 22.2%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables Tables-31

Table 4-11

Demographic and Employment Baseline Projections for Economic Impact Area FL-2 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 619.13 659.96 661.80 670.02 678.38 686.86 695.39 730.00 782.71 826.55 913.81

Age Under 19 Years 26.0% 24.9% 24.7% 23.9% 23.6% 23.6% 23.6% 23.8% 23.6% 23.3% 22.6%

Age 20 to 34 24.1% 24.2% 24.4% 24.9% 25.0% 24.7% 24.2% 22.6% 20.1% 19.1% 19.7%

Age 35 to 49 20.5% 18.9% 18.5% 18.2% 17.9% 17.8% 17.8% 18.4% 20.1% 21.0% 17.9%

Age 50 to 64 17.6% 19.2% 19.3% 19.3% 19.3% 19.4% 19.3% 18.5% 17.1% 16.3% 19.0%

Age 65 and over 11.8% 12.8% 13.2% 13.7% 14.1% 14.5% 15.0% 16.7% 19.0% 20.3% 20.9%

Median Age of Population (years) 37.9 39.3 39.4 39.7 39.9 40.0 40.2 40.8 41.8 42.7 43.6

White Population (in thousands) 66.7% 65.0% 64.6% 64.5% 64.3% 64.1% 63.9% 63.2% 61.9% 60.8% 58.6%

Black Population (in thousands) 26.8% 27.2% 27.2% 27.2% 27.3% 27.3% 27.4% 27.7% 28.3% 28.8% 29.8%

Native American Population (in thousands) 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4%

Asian and Pacific Islander Population (in thousands) 1.5% 1.7% 1.8% 1.8% 1.8% 1.9% 1.9% 2.0% 2.1% 2.2% 2.3%

Hispanic or Latino Population (in thousands) 4.6% 5.7% 5.9% 6.0% 6.1% 6.2% 6.3% 6.7% 7.2% 7.8% 8.8%

Male Population (in thousands) 50.4% 50.9% 50.8% 50.9% 51.0% 51.1% 51.1% 51.4% 51.7% 51.8% 52.1%

Total Employment (in thousands of jobs) 322.62 322.32 323.02 324.07 328.11 332.19 336.31 353.35 380.57 404.92 458.68

Farm Employment 2.6% 2.9% 2.9% 2.9% 2.9% 2.8% 2.8% 2.7% 2.6% 2.5% 2.3%

Forestry, Fishing, Related Activities 1.3% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.5% 1.5% 1.4%

Mining 0.2% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2% 0.2% 0.2% 0.2%

Utilities 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3%

Construction 6.5% 4.9% 4.8% 5.0% 5.0% 5.0% 5.0% 4.9% 4.9% 4.8% 4.7%

Manufacturing 4.6% 3.7% 3.8% 3.9% 3.8% 3.8% 3.7% 3.6% 3.3% 3.1% 2.7%

Wholesale Trade 2.1% 2.0% 2.0% 2.2% 2.2% 2.1% 2.1% 2.1% 2.0% 2.0% 1.9%

Retail Trade 11.0% 9.9% 9.9% 10.0% 10.0% 10.0% 10.0% 10.0% 9.9% 9.8% 9.7%

Transportation and Warehousing 1.6% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4%

Information Employment 1.8% 1.5% 1.4% 1.4% 1.4% 1.4% 1.3% 1.3% 1.3% 1.2% 1.2%

Finance and Insurance 3.2% 3.9% 3.9% 3.8% 3.8% 3.8% 3.8% 3.8% 3.9% 3.9% 4.0%

Real Estate/Rental and Lease 3.1% 3.1% 3.1% 3.0% 3.0% 3.0% 3.1% 3.1% 3.2% 3.2% 3.2%

Professional and Technical Services 5.8% 6.0% 5.8% 5.7% 5.7% 5.8% 5.8% 5.9% 6.1% 6.3% 6.5%

Management 0.3% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Administrative and Waste Services 4.8% 4.8% 4.7% 4.8% 4.8% 4.8% 4.9% 5.0% 5.3% 5.4% 5.8%

Educational Services 1.1% 1.5% 1.5% 1.5% 1.5% 1.5% 1.6% 1.7% 1.9% 2.1% 2.5%
Tables-32 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-11. Demographic and Employment Baseline Projections for Economic Impact Area FL-2 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 8.6% 10.0% 10.2% 10.3% 10.4% 10.5% 10.7% 11.2% 12.1% 12.8% 14.4%

Arts, Entertainment, and Recreation 1.2% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.5% 1.5% 1.6% 1.7%

Accommodation and Food Services 6.6% 6.8% 6.8% 6.7% 6.7% 6.7% 6.8% 6.8% 6.9% 6.9% 7.0%

Other Services, Except Public Administration 6.2% 6.1% 6.2% 6.2% 6.2% 6.2% 6.2% 6.3% 6.4% 6.5% 6.5%

Federal Civilian Government 1.2% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.3% 1.2% 1.2% 1.0%

Federal Military 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3%

State and Local Government 25.3% 26.1% 26.1% 25.9% 25.7% 25.6% 25.4% 24.7% 23.7% 22.8% 21.2%

Total Earnings (in millions of 2005 dollars) 11,927.62 11,830.85 11,712.99 11,626.75 11,900.96 12,162.84 12,430.40 13,560.23 15,449.18 17,222.67 21,408.09

Farm 1.3% 1.2% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2% 1.1% 1.1% 1.0%

Forestry, Fishing, Related Activities 1.3% 1.4% 1.4% 1.4% 1.5% 1.5% 1.4% 1.4% 1.3% 1.3% 1.2%

Mining 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Utilities 0.8% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.6% 0.6% 0.6% 0.6%

Construction 6.4% 4.5% 4.4% 4.5% 4.5% 4.4% 4.4% 4.3% 4.0% 3.9% 3.5%

Manufacturing 5.9% 5.3% 5.4% 5.5% 5.4% 5.4% 5.3% 5.2% 5.0% 4.8% 4.5%

Wholesale Trade 2.7% 2.4% 2.5% 2.6% 2.7% 2.7% 2.6% 2.6% 2.6% 2.5% 2.4%

Retail Trade 7.2% 6.8% 6.9% 7.1% 7.0% 6.9% 6.9% 6.6% 6.2% 5.9% 5.3%

Transportation and Warehousing 1.5% 1.1% 1.1% 1.0% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0%

Information 2.4% 2.0% 1.9% 1.9% 1.8% 1.9% 1.9% 1.9% 1.9% 1.9% 2.0%

Finance and Insurance 4.2% 4.3% 4.3% 4.2% 4.2% 4.3% 4.3% 4.4% 4.5% 4.6% 4.7%

Real Estate/Rental and Lease 1.1% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8%

Professional and Technical Services 7.9% 8.2% 8.2% 8.2% 8.2% 8.3% 8.3% 8.6% 9.1% 9.5% 10.3%

Management 0.4% 0.4% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3%

Administrative and Waste Services 2.8% 2.9% 3.0% 3.2% 3.2% 3.2% 3.3% 3.4% 3.6% 3.8% 4.1%

Educational Services 0.5% 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% 0.9% 1.0% 1.2%

Health Care and Social Assistance 9.5% 11.3% 11.5% 11.7% 11.8% 12.0% 12.1% 12.8% 13.8% 14.7% 16.5%

Arts, Entertainment, and Recreation 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

Accommodation and Food Services 2.7% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8%

Other Services, Except Public Administration 5.2% 5.1% 5.2% 5.2% 5.2% 5.2% 5.2% 5.3% 5.3% 5.3% 5.3%

Federal Civilian Government 2.7% 3.2% 3.1% 3.1% 3.1% 3.1% 3.1% 3.0% 2.9% 2.9% 2.7%

Federal Military 0.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6%

State and Local Government 32.3% 34.1% 33.5% 32.9% 32.7% 32.5% 32.4% 31.8% 30.9% 30.1% 28.6%

Total Personal Income per Capita (in 2005 dollars) 26,967 26,978 27,107 26,654 26,837 27,090 27,407 29,022 32,034 35,017 42,303

Woods & Poole Economics Wealth Index (U.S. = 100) 66.4 66.8 66.0 64.9 65.1 65.1 65.1 65.1 65.0 65.0 64.9

Persons per Household (in number of people) 2.6 2.7 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.7
Tables Tables-33

Table 4-11. Demographic and Employment Baseline Projections for Economic Impact Area FL-2 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Mean Household Total Personal Income (in 2005 dollars) 70,426 71,664 71,763 70,245 70,421 70,757 71,281 74,883 83,068 91,805 113,624

Number of Households (in thousands) 237.07 248.45 249.98 254.23 258.53 262.97 267.37 282.92 301.84 315.27 340.21

Income <$10,000 (thousands of households, 2000$) 13.7% 12.6% 12.4% 12.4% 12.2% 12.0% 11.8% 10.9% 9.2% 7.9% 5.9%

Income $10,000 to $19,999 14.3% 13.2% 13.0% 13.0% 12.7% 12.6% 12.4% 11.4% 9.6% 8.3% 6.1%

Income $20,000 to $29,999 13.9% 12.9% 12.7% 12.6% 12.4% 12.2% 12.1% 11.1% 9.4% 8.1% 6.0%

Income $30,000 to $44,999 18.7% 18.7% 18.7% 18.7% 18.6% 18.4% 18.3% 17.4% 15.0% 12.9% 9.4%

Income $45,000 to $59,999 14.1% 15.3% 15.6% 15.6% 15.9% 16.1% 16.4% 17.6% 19.3% 19.2% 15.5%

Income $60,000 to $74,999 9.3% 10.1% 10.3% 10.3% 10.5% 10.6% 10.8% 11.8% 13.9% 16.3% 20.0%

Income $75,000 to $99,999 8.1% 8.8% 8.9% 8.9% 9.1% 9.2% 9.4% 10.2% 12.1% 14.1% 19.3%

Income $100,000 or more 7.7% 8.3% 8.5% 8.5% 8.6% 8.8% 8.9% 9.7% 11.4% 13.2% 18.0%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables-34 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-12

Demographic and Employment Baseline Projections for Economic Impact Area FL-3 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 3,435.22 3,626.40 3,663.94 3,721.36 3,779.50 3,838.27 3,897.31 4,136.02 4,498.17 4,799.12 5,397.92

Age Under 19 Years 23.9% 23.2% 22.8% 22.7% 22.6% 22.5% 22.5% 22.5% 22.6% 22.6% 22.9%

Age 20 to 34 18.5% 18.6% 18.9% 19.1% 19.2% 19.2% 19.2% 18.9% 18.3% 18.0% 18.4%

Age 35 to 49 21.3% 19.8% 19.4% 18.9% 18.6% 18.2% 18.0% 17.6% 17.8% 18.3% 17.7%

Age 50 to 64 18.5% 20.2% 20.6% 20.7% 20.7% 20.8% 20.8% 20.3% 18.6% 16.9% 16.8%

Age 65 and over 17.8% 18.2% 18.3% 18.6% 18.9% 19.2% 19.5% 20.6% 22.8% 24.2% 24.2%

Median Age of Population (years) 41.7 42.9 43.3 43.5 43.7 43.8 44.0 44.4 44.6 44.8 44.7

White Population (in thousands) 73.9% 70.0% 69.4% 68.9% 68.4% 67.8% 67.3% 65.2% 62.0% 59.2% 53.5%

Black Population (in thousands) 11.4% 12.0% 12.3% 12.4% 12.4% 12.5% 12.6% 12.8% 13.2% 13.4% 13.8%

Native American Population (in thousands) 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2%

Asian and Pacific Islander Population 

(in thousands)

2.6% 3.1% 3.2% 3.3% 3.3% 3.4% 3.5% 3.8% 4.2% 4.6% 5.4%

Hispanic or Latino Population (in thousands) 11.8% 14.5% 14.8% 15.2% 15.6% 15.9% 16.3% 17.9% 20.4% 22.5% 27.1%

Male Population (in thousands) 48.6% 48.6% 48.6% 48.6% 48.7% 48.7% 48.7% 48.8% 48.9% 48.9% 48.9%

Total Employment (in thousands of jobs) 1,944.15 1,842.54 1,880.65 1,915.18 1,945.11 1,975.41 2,006.07 2,132.46 2,333.86 2,513.15 2,905.81

Farm Employment 1.0% 1.2% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 0.9%

Forestry, Fishing, Related Activities 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4%

Mining 0.1% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Utilities 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0.3% 0.3% 0.3%

Construction 7.3% 5.1% 4.8% 4.9% 4.9% 4.9% 4.9% 4.9% 5.0% 5.1% 5.2%

Manufacturing 5.0% 4.1% 4.2% 4.2% 4.2% 4.1% 4.0% 3.8% 3.5% 3.2% 2.7%

Wholesale Trade 3.4% 3.2% 3.1% 3.1% 3.1% 3.1% 3.1% 3.1% 3.0% 3.0% 2.9%

Retail Trade 11.4% 11.2% 11.3% 11.6% 11.7% 11.7% 11.7% 11.8% 12.0% 12.1% 12.2%

Transportation and Warehousing 2.3% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2%

Information Employment 2.2% 1.9% 1.8% 1.8% 1.8% 1.8% 1.8% 1.7% 1.7% 1.6% 1.5%

Finance and Insurance 5.8% 6.8% 6.9% 6.6% 6.6% 6.6% 6.5% 6.5% 6.3% 6.2% 5.9%

Real Estate/Rental and Lease 4.5% 4.4% 4.4% 4.2% 4.2% 4.2% 4.1% 4.1% 4.0% 3.9% 3.7%

Professional and Technical Services 6.4% 7.2% 7.2% 7.3% 7.3% 7.3% 7.3% 7.3% 7.2% 7.2% 7.1%

Management 0.8% 1.2% 1.3% 1.4% 1.4% 1.4% 1.4% 1.4% 1.5% 1.5% 1.6%

Administrative and Waste Services 10.8% 7.9% 7.7% 7.7% 7.7% 7.7% 7.7% 7.6% 7.6% 7.5% 7.4%

Educational Services 1.3% 1.8% 1.9% 1.9% 1.9% 1.9% 2.0% 2.1% 2.4% 2.7% 3.2%

Health Care and Social Assistance 10.3% 12.3% 12.5% 12.5% 12.6% 12.7% 12.8% 13.2% 13.7% 14.2% 15.1%
Tables Tables-35

Table 4-12. Demographic and Employment Baseline Projections for Economic Impact Area FL-3 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Arts, Entertainment, and Recreation 2.0% 2.4% 2.5% 2.6% 2.7% 2.7% 2.7% 2.8% 3.0% 3.1% 3.4%

Accommodation and Food Services 6.8% 7.1% 7.2% 7.3% 7.2% 7.2% 7.2% 7.0% 6.8% 6.6% 6.2%

Other Services, Except Public Administration 5.9% 6.0% 6.0% 6.0% 6.0% 6.0% 6.1% 6.3% 6.5% 6.8% 7.3%

Federal Civilian Government 1.3% 1.6% 1.6% 1.7% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.5%

Federal Military 0.7% 0.8% 0.8% 0.8% 0.8% 0.7% 0.7% 0.7% 0.6% 0.6% 0.5%

State and Local Government 9.9% 10.6% 10.4% 10.2% 10.1% 10.1% 10.0% 9.8% 9.4% 9.1% 8.5%

Total Earnings (in millions of 2005 dollars) 79,115.35 75,206.53 75,733.42 76,242.07 78,415.64 80,420.58 82,471.24 91,149.87 105,706.84 119,398.09 151,682.46

Farm 0.5% 0.3% 0.3% 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3%

Forestry, Fishing, Related Activities 0.3% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Mining 0.3% 0.1% 0.1% 0.1% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.4%

Utilities 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%

Construction 7.5% 4.8% 4.5% 4.5% 4.4% 4.4% 4.4% 4.3% 4.2% 4.1% 3.8%

Manufacturing 6.8% 6.1% 6.2% 6.3% 6.3% 6.2% 6.2% 5.9% 5.6% 5.3% 4.8%

Wholesale Trade 4.9% 4.8% 4.7% 4.7% 4.6% 4.6% 4.6% 4.6% 4.6% 4.6% 4.5%

Retail Trade 8.3% 7.8% 7.9% 8.2% 8.1% 8.1% 8.0% 7.8% 7.4% 7.1% 6.5%

Transportation and Warehousing 2.2% 2.1% 2.2% 2.1% 2.1% 2.1% 2.1% 2.0% 2.0% 1.9% 1.8%

Information 3.3% 3.0% 2.9% 2.7% 2.7% 2.7% 2.7% 2.7% 2.7% 2.8% 2.8%

Finance and Insurance 8.0% 7.8% 7.8% 7.5% 7.5% 7.5% 7.5% 7.4% 7.2% 7.1% 6.8%

Real Estate/Rental and Lease 2.3% 1.5% 1.4% 1.4% 1.4% 1.3% 1.3% 1.3% 1.2% 1.2% 1.1%

Professional and Technical Services 8.1% 9.7% 10.0% 10.1% 10.1% 10.1% 10.2% 10.3% 10.4% 10.5% 10.7%

Management 1.6% 2.3% 2.5% 2.8% 2.8% 2.9% 2.9% 3.1% 3.3% 3.5% 3.9%

Administrative and Waste Services 7.1% 5.2% 5.0% 5.0% 5.0% 5.0% 5.0% 5.0% 5.0% 5.0% 5.0%

Educational Services 0.8% 1.2% 1.3% 1.3% 1.3% 1.4% 1.4% 1.5% 1.8% 2.0% 2.5%

Health Care and Social Assistance 12.1% 14.6% 14.6% 14.6% 14.7% 14.8% 14.9% 15.3% 16.0% 16.6% 17.7%

Arts, Entertainment, and Recreation 1.5% 1.8% 1.9% 2.0% 2.0% 2.0% 2.0% 2.1% 2.2% 2.3% 2.4%

Accommodation and Food Services 3.9% 3.7% 3.9% 3.9% 3.9% 3.9% 3.9% 3.8% 3.6% 3.5% 3.3%

Other Services, Except Public Administration 4.0% 3.8% 3.8% 3.7% 3.7% 3.8% 3.8% 3.8% 4.0% 4.0% 4.2%

Federal Civilian Government 2.7% 3.5% 3.5% 3.4% 3.4% 3.4% 3.4% 3.5% 3.6% 3.6% 3.7%

Federal Military 1.2% 1.6% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.4%

State and Local Government 11.8% 13.2% 13.0% 12.6% 12.5% 12.5% 12.4% 12.3% 11.9% 11.7% 11.2%

Total Personal Income per Capita (in 2005 dollars) 33,038 32,184 32,448 32,086 32,189 32,388 32,679 34,329 37,521 40,713 48,510

Woods & Poole Economics Wealth Index 

(U.S. = 100)

78.9 77.6 76.9 75.6 75.8 75.8 75.8 76.0 76.2 76.3 76.6
Tables-36 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-12. Demographic and Employment Baseline Projections for Economic Impact Area FL-3 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Persons per Household (in number of people) 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.3 2.4 2.4 2.4

Mean Household Total Personal Income 

(in 2005 dollars)

78,298 77,951 78,338 77,085 76,977 77,075 77,425 80,614 88,451 96,951 118,165

Number of Households (in thousands) 1,449.50 1,497.25 1,517.61 1,549.00 1,580.47 1,612.89 1,644.98 1,761.29 1,908.13 2,015.30 2,216.00

Income <$10,000 (thousands of households, 

2000$)

9.0% 8.4% 8.3% 8.2% 8.1% 8.0% 7.9% 7.2% 6.1% 5.3% 4.0%

Income $10,000 to $19,999 13.6% 12.8% 12.5% 12.4% 12.3% 12.1% 11.9% 10.9% 9.2% 8.0% 6.0%

Income $20,000 to $29,999 14.5% 13.6% 13.3% 13.3% 13.1% 12.9% 12.7% 11.7% 9.9% 8.5% 6.4%

Income $30,000 to $44,999 19.6% 19.1% 18.8% 18.8% 18.6% 18.4% 18.3% 17.0% 14.4% 12.5% 9.4%

Income $45,000 to $59,999 15.3% 16.3% 16.7% 16.7% 17.0% 17.2% 17.4% 18.5% 19.4% 18.3% 14.2%

Income $60,000 to $74,999 9.9% 10.6% 10.8% 10.8% 11.0% 11.1% 11.3% 12.3% 14.6% 16.9% 19.5%

Income $75,000 to $99,999 8.5% 9.1% 9.3% 9.3% 9.5% 9.6% 9.7% 10.6% 12.5% 14.5% 19.3%

Income $100,000 or more 9.6% 10.1% 10.4% 10.4% 10.6% 10.7% 10.8% 11.7% 13.8% 16.0% 21.2%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables Tables-37

Table 4-13

Demographic and Employment Baseline Projections for Economic Impact Area FL-4 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 5,934.95 6,170.12 6,273.04 6,360.03 6,448.27 6,537.57 6,627.34 6,990.77 7,542.74 8,001.19 8,912.76

Age Under 19 Years 24.4% 23.3% 23.0% 22.8% 22.7% 22.6% 22.5% 22.3% 22.0% 21.9% 21.6%

Age 20 to 34 18.4% 18.3% 18.6% 18.6% 18.7% 18.8% 18.8% 18.6% 17.9% 17.3% 17.3%

Age 35 to 49 22.2% 21.1% 20.7% 20.3% 19.9% 19.5% 19.2% 18.5% 18.2% 18.5% 17.6%

Age 50 to 64 17.8% 19.4% 19.7% 19.8% 19.9% 20.1% 20.2% 20.1% 19.2% 17.6% 16.8%

Age 65 and over 17.1% 17.9% 18.1% 18.4% 18.8% 19.0% 19.4% 20.6% 22.7% 24.7% 26.6%

Median Age of Population (years) 44.0 45.5 45.9 46.0 46.2 46.3 46.4 46.9 46.9 46.9 46.6

White Population (in thousands) 45.8% 42.3% 42.1% 41.6% 41.1% 40.6% 40.1% 38.3% 35.6% 33.4% 29.3%

Black Population (in thousands) 16.7% 16.7% 16.8% 16.8% 16.8% 16.8% 16.9% 16.9% 17.0% 17.1% 17.2%

Native American Population (in thousands) 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.1%

Asian and Pacific Islander Population (in thousands) 2.0% 2.2% 2.2% 2.3% 2.3% 2.4% 2.4% 2.5% 2.7% 2.9% 3.1%

Hispanic or Latino Population (in thousands) 35.3% 38.6% 38.7% 39.2% 39.6% 40.0% 40.5% 42.1% 44.4% 46.5% 50.2%

Male Population (in thousands) 48.6% 48.6% 48.7% 48.7% 48.7% 48.7% 48.7% 48.7% 48.7% 48.6% 48.4%

Total Employment (in thousands of jobs) 3,395.35 3,351.08 3,452.11 3,548.46 3,610.06 3,672.52 3,735.84 3,997.92 4,418.49 4,795.40 5,626.66

Farm Employment 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4%

Forestry, Fishing, Related Activities 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

Mining 0.1% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.3%

Utilities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.1% 0.1%

Construction 8.0% 5.0% 4.8% 4.7% 4.7% 4.7% 4.7% 4.8% 4.8% 4.9% 4.9%

Manufacturing 3.6% 2.8% 2.7% 2.8% 2.7% 2.6% 2.6% 2.4% 2.1% 1.9% 1.6%

Wholesale Trade 4.5% 4.3% 4.3% 4.5% 4.4% 4.4% 4.4% 4.3% 4.1% 4.0% 3.7%

Retail Trade 11.2% 11.1% 11.2% 11.4% 11.5% 11.5% 11.5% 11.5% 11.5% 11.5% 11.4%

Transportation and Warehousing 3.8% 3.7% 3.8% 3.7% 3.7% 3.8% 3.8% 3.8% 3.8% 3.8% 3.8%

Information Employment 2.0% 1.6% 1.6% 1.6% 1.6% 1.6% 1.5% 1.5% 1.4% 1.4% 1.3%

Finance and Insurance 5.0% 6.1% 6.3% 6.1% 6.1% 6.1% 6.1% 6.1% 6.0% 6.0% 6.0%

Real Estate/Rental and Lease 6.0% 6.2% 6.2% 6.0% 6.0% 6.0% 6.0% 5.9% 5.9% 5.8% 5.8%

Professional and Technical Services 6.5% 7.0% 7.0% 7.1% 7.1% 7.1% 7.2% 7.2% 7.3% 7.3% 7.4%

Management 0.7% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.9%

Administrative and Waste Services 9.0% 8.1% 8.1% 8.2% 8.3% 8.3% 8.4% 8.6% 9.0% 9.3% 9.9%

Educational Services 1.8% 2.4% 2.5% 2.4% 2.4% 2.5% 2.5% 2.6% 2.7% 2.8% 3.0%

Health Care and Social Assistance 9.1% 10.7% 10.7% 10.7% 10.7% 10.8% 10.8% 11.1% 11.4% 11.6% 12.1%
Tables-38 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-13. Demographic and Employment Baseline Projections for Economic Impact Area FL-4 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Arts, Entertainment, and Recreation 2.2% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2.3%

Accommodation and Food Services 7.2% 7.7% 7.9% 8.2% 8.2% 8.1% 8.1% 8.1% 8.1% 8.0% 8.0%

Other Services, Except Public Administration 7.7% 8.1% 8.1% 8.1% 8.1% 8.2% 8.2% 8.3% 8.5% 8.6% 8.9%

Federal Civilian Government 1.0% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 0.9%

Federal Military 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.3%

State and Local Government 9.0% 9.0% 8.7% 8.4% 8.3% 8.3% 8.2% 8.0% 7.6% 7.3% 6.7%

Total Earnings (in millions of 2005 dollars) 146,349.28 135,702.12 137,788.29 140,117.22 143,722.21 147,475.18 151,316.36 167,601.21 195,009.39 220,880.16 282,175.15

Farm 0.5% 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.3%

Forestry, Fishing, Related Activities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Mining 0.1% 0.0% 0.0% 0.0% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1%

Utilities 0.4% 0.5% 0.5% 0.4% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.4%

Construction 9.4% 5.6% 5.3% 5.2% 5.2% 5.2% 5.1% 5.0% 4.9% 4.8% 4.5%

Manufacturing 4.4% 3.8% 3.8% 3.9% 3.9% 3.8% 3.8% 3.6% 3.3% 3.1% 2.7%

Wholesale Trade 6.8% 7.1% 7.2% 7.5% 7.4% 7.4% 7.4% 7.3% 7.1% 6.9% 6.6%

Retail Trade 8.5% 8.3% 8.4% 8.7% 8.6% 8.6% 8.5% 8.2% 7.8% 7.5% 6.8%

Transportation and Warehousing 4.0% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.0% 3.9% 3.9% 3.7%

Information 3.6% 3.1% 3.2% 3.3% 3.3% 3.3% 3.3% 3.3% 3.3% 3.3% 3.4%

Finance and Insurance 6.9% 6.8% 6.9% 6.7% 6.6% 6.6% 6.6% 6.7% 6.7% 6.7% 6.7%

Real Estate/Rental and Lease 3.7% 2.1% 2.1% 2.0% 2.0% 2.0% 2.0% 1.9% 1.9% 1.8% 1.8%

Professional and Technical Services 8.3% 9.6% 9.8% 10.0% 10.1% 10.2% 10.2% 10.5% 10.8% 11.1% 11.7%

Management 1.3% 1.8% 1.8% 1.8% 1.8% 1.8% 1.9% 2.0% 2.2% 2.4% 2.8%

Administrative and Waste Services 6.2% 5.0% 5.0% 5.2% 5.2% 5.3% 5.3% 5.5% 5.8% 6.0% 6.5%

Educational Services 1.5% 2.1% 2.1% 2.0% 2.0% 2.0% 2.1% 2.2% 2.3% 2.4% 2.7%

Health Care and Social Assistance 9.5% 12.0% 11.9% 11.9% 12.0% 12.0% 12.1% 12.5% 12.9% 13.3% 14.1%

Arts, Entertainment, and Recreation 1.6% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.6% 1.6% 1.6%

Accommodation and Food Services 4.3% 4.7% 4.9% 5.1% 5.1% 5.1% 5.1% 5.1% 5.1% 5.1% 5.0%

Other Services, Except Public Administration 4.2% 4.6% 4.6% 4.6% 4.6% 4.6% 4.6% 4.7% 4.8% 4.8% 5.0%

Federal Civilian Government 2.2% 2.6% 2.5% 2.5% 2.5% 2.5% 2.5% 2.4% 2.4% 2.4% 2.3%

Federal Military 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6%

State and Local Government 11.8% 13.3% 12.7% 12.1% 12.0% 12.0% 11.9% 11.7% 11.4% 11.1% 10.5%

Total Personal Income per Capita (in 2005 dollars) 37,492 36,585 36,920 36,834 36,830 37,094 37,486 39,719 44,049 48,404 59,208

Woods & Poole Economics Wealth Index (U.S. = 100) 118.7 115.0 114.1 112.9 112.7 112.6 112.6 113.3 114.9 116.4 119.8

Persons per Household (in number of people) 2.5 2.6 2.6 2.6 2.6 2.5 2.5 2.5 2.5 2.5 2.6

Mean Household Total Personal Income (in 2005 dollars) 94,609 94,796 95,361 94,651 94,174 94,359 94,905 99,547 110,629 122,624 152,996
Tables Tables-39

Table 4-13. Demographic and Employment Baseline Projections for Economic Impact Area FL-4 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Number of Households (in thousands) 2,351.92 2,381.27 2,428.65 2,475.06 2,521.79 2,570.01 2,617.71 2,789.28 3,003.29 3,158.35 3,449.13

Income <$10,000 (thousands of households, 2000$) 9.1% 8.5% 8.4% 8.3% 8.2% 8.1% 8.0% 7.4% 6.3% 5.6% 4.2%

Income $10,000 to $19,999 12.1% 11.3% 11.2% 11.1% 11.0% 10.8% 10.7% 9.9% 8.5% 7.4% 5.6%

Income $20,000 to $29,999 12.6% 11.9% 11.7% 11.6% 11.5% 11.4% 11.2% 10.3% 8.9% 7.8% 5.8%

Income $30,000 to $44,999 17.3% 16.5% 16.3% 16.2% 16.0% 15.8% 15.6% 14.4% 12.4% 10.9% 8.1%

Income $45,000 to $59,999 15.0% 15.7% 15.9% 16.0% 16.1% 16.2% 16.3% 16.6% 15.7% 14.0% 10.5%

Income $60,000 to $74,999 10.7% 11.3% 11.5% 11.6% 11.7% 11.9% 12.0% 13.1% 15.1% 16.5% 15.2%

Income $75,000 to $99,999 10.1% 10.7% 10.8% 10.9% 11.0% 11.2% 11.3% 12.3% 14.3% 16.4% 21.5%

Income $100,000 or more 13.2% 14.0% 14.2% 14.3% 14.4% 14.6% 14.8% 16.1% 18.8% 21.4% 29.1%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables-40 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-14

Demographic and Employment Baseline Projections for Economic Impact Area LA-1 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 338.48 346.02 346.51 349.64 352.85 356.11 359.40 372.82 393.34 410.37 444.18

Age Under 19 Years 29.3% 28.5% 28.0% 28.2% 28.3% 28.3% 28.3% 28.7% 28.9% 28.5% 27.5%

Age 20 to 34 21.6% 21.3% 21.5% 21.2% 20.9% 20.7% 20.4% 18.9% 17.9% 18.3% 19.6%

Age 35 to 49 20.9% 19.3% 19.0% 18.8% 18.6% 18.5% 18.5% 19.0% 19.3% 18.5% 16.6%

Age 50 to 64 16.4% 18.5% 18.9% 18.9% 19.1% 19.2% 19.2% 18.7% 17.2% 16.8% 18.0%

Age 65 and over 11.8% 12.4% 12.6% 12.9% 13.1% 13.3% 13.5% 14.6% 16.7% 17.9% 18.3%

Median Age of Population (years) 34.9 36.2 36.3 36.4 36.5 36.6 36.8 37.4 38.0 38.2 38.4

White Population (in thousands) 74.8% 73.4% 73.0% 72.8% 72.7% 72.6% 72.5% 72.1% 71.4% 70.7% 69.3%

Black Population (in thousands) 20.7% 21.4% 21.6% 21.6% 21.6% 21.6% 21.6% 21.6% 21.6% 21.6% 21.5%

Native American Population (in thousands) 0.7% 0.9% 0.8% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%

Asian and Pacific Islander Population (in thousands) 1.0% 1.2% 1.2% 1.3% 1.3% 1.3% 1.3% 1.4% 1.6% 1.7% 1.9%

Hispanic or Latino Population (in thousands) 2.7% 3.1% 3.3% 3.4% 3.5% 3.6% 3.7% 4.0% 4.6% 5.2% 6.4%

Male Population (in thousands) 50.0% 50.0% 49.9% 49.9% 50.0% 50.0% 50.0% 50.1% 50.1% 50.1% 50.1%

Total Employment (in thousands of jobs) 171.64 177.41 175.82 175.74 177.96 180.22 182.51 191.90 206.92 220.30 249.67

Farm Employment 1.9% 2.0% 2.0% 1.9% 1.9% 1.9% 1.9% 1.9% 1.8% 1.7% 1.6%

Forestry, Fishing, Related Activities 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.1% 1.1% 1.1%

Mining 1.1% 1.2% 1.2% 1.2% 1.2% 1.1% 1.1% 1.1% 1.1% 1.0% 0.9%

Utilities 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0.2%

Construction 8.7% 8.0% 7.6% 7.4% 7.4% 7.4% 7.5% 7.6% 7.7% 7.8% 7.9%

Manufacturing 6.7% 6.5% 6.8% 7.2% 7.0% 6.8% 6.7% 6.0% 5.2% 4.6% 3.5%

Wholesale Trade 2.2% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.0% 2.0% 1.9% 1.8%

Retail Trade 11.0% 10.3% 10.2% 10.2% 10.3% 10.3% 10.4% 10.5% 10.8% 10.9% 11.2%

Transportation and Warehousing 3.2% 2.8% 2.8% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9%

Information Employment 1.0% 0.9% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7% 0.7% 0.7% 0.6%

Finance and Insurance 2.5% 3.0% 3.2% 3.0% 3.0% 3.0% 2.9% 2.9% 2.8% 2.7% 2.5%

Real Estate/Rental and Lease 2.4% 2.8% 2.9% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.7%

Professional and Technical Services 4.7% 4.2% 4.2% 4.2% 4.3% 4.3% 4.3% 4.5% 4.7% 4.9% 5.3%

Management 0.7% 0.8% 0.8% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%

Administrative and Waste Services 3.8% 4.3% 4.3% 4.3% 4.3% 4.4% 4.4% 4.6% 4.8% 5.0% 5.4%

Educational Services 1.0% 1.1% 1.2% 1.3% 1.3% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1%

Health Care and Social Assistance 9.5% 10.4% 10.4% 10.2% 10.4% 10.5% 10.7% 11.3% 12.2% 13.0% 14.6%
Tables Tables-41

Table 4-14. Demographic and Employment Baseline Projections for Economic Impact Area LA-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Arts, Entertainment, and Recreation 2.3% 1.4% 1.4% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2% 1.1% 1.0%

Accommodation and Food Services 7.9% 7.8% 8.0% 8.1% 8.2% 8.2% 8.3% 8.4% 8.7% 8.9% 9.2%

Other Services, Except Public Administration 6.2% 6.3% 6.3% 6.4% 6.4% 6.5% 6.6% 6.8% 7.1% 7.4% 8.0%

Federal Civilian Government 2.1% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.1% 2.0% 1.9% 1.7%

Federal Military 5.7% 6.3% 6.3% 6.3% 6.3% 6.2% 6.1% 5.9% 5.5% 5.1% 4.6%

State and Local Government 14.0% 14.3% 13.9% 13.9% 13.8% 13.7% 13.6% 13.3% 12.7% 12.3% 11.3%

Total Earnings (in millions of 2005 dollars) 6,873.26 7,544.84 7,610.27 7,610.52 7,850.34 8,014.26 8,181.56 8,886.17 10,058.07 11,152.07 13,712.63

Farm 0.5% 0.3% 0.3% 0.3% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4%

Forestry, Fishing, Related Activities 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%

Mining 1.7% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.3% 1.3% 1.3%

Utilities 0.8% 0.8% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.8% 0.8% 0.7%

Construction 7.6% 8.1% 7.5% 7.1% 7.1% 7.0% 7.0% 6.9% 6.8% 6.6% 6.3%

Manufacturing 14.6% 14.0% 14.9% 15.9% 15.5% 15.2% 14.9% 13.8% 12.2% 11.0% 8.8%

Wholesale Trade 2.7% 2.6% 2.5% 2.4% 2.4% 2.4% 2.4% 2.3% 2.3% 2.3% 2.2%

Retail Trade 6.3% 5.6% 5.6% 5.5% 5.4% 5.4% 5.4% 5.3% 5.1% 5.0% 4.7%

Transportation and Warehousing 3.6% 3.2% 3.4% 3.5% 3.4% 3.4% 3.4% 3.4% 3.4% 3.3% 3.3%

Information 2.6% 1.0% 0.9% 1.0% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2% 1.2%

Finance and Insurance 2.3% 2.3% 2.3% 2.2% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.0%

Real Estate/Rental and Lease 1.2% 1.3% 1.3% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1%

Professional and Technical Services 5.4% 5.0% 5.0% 5.0% 5.1% 5.1% 5.2% 5.5% 6.0% 6.4% 7.2%

Management 1.5% 0.6% 0.6% 0.6% 0.9% 0.9% 0.9% 1.0% 1.0% 1.1% 1.2%

Administrative and Waste Services 2.3% 2.4% 2.4% 2.4% 2.4% 2.5% 2.5% 2.7% 2.9% 3.1% 3.5%

Educational Services 0.6% 0.7% 0.7% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8%

Health Care and Social Assistance 8.7% 10.6% 10.6% 10.5% 10.6% 10.8% 10.9% 11.7% 12.9% 13.9% 16.1%

Arts, Entertainment, and Recreation 1.5% 0.6% 0.6% 0.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5%

Accommodation and Food Services 3.7% 3.9% 3.8% 3.8% 3.8% 3.8% 3.8% 3.9% 4.1% 4.2% 4.4%

Other Services, Except Public Administration 3.7% 3.5% 3.5% 3.5% 3.5% 3.6% 3.6% 3.7% 3.9% 4.0% 4.3%

Federal Civilian Government 3.8% 3.9% 3.8% 3.8% 3.7% 3.7% 3.7% 3.7% 3.6% 3.6% 3.5%

Federal Military 10.6% 13.2% 13.6% 13.4% 13.4% 13.4% 13.5% 13.6% 13.7% 13.8% 13.8%

State and Local Government 13.8% 14.3% 13.8% 13.6% 13.4% 13.4% 13.3% 13.2% 13.0% 12.7% 12.2%

Total Personal Income per Capita (in 2005 dollars) 27,227 30,312 30,763 30,470 30,593 30,948 31,371 33,456 37,259 40,991 50,082

Woods & Poole Economics Wealth Index (U.S. = 100) 69.2 80.2 79.9 79.1 79.1 79.4 79.7 80.6 81.9 82.9 84.6

Persons per Household (in number of people) 2.6 2.7 2.7 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6

Mean Household Total Personal Income (in 2005 dollars) 71,904 80,936 81,820 80,597 80,477 80,944 81,615 85,962 95,585 105,750 130,964
Tables-42 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-14. Demographic and Employment Baseline Projections for Economic Impact Area LA-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Number of Households (in thousands) 128.17 129.59 130.28 132.19 134.13 136.16 138.15 145.10 153.32 159.07 169.86

Income <$10,000 (thousands of households, 2000$) 12.2% 10.7% 10.5% 10.5% 10.3% 10.2% 10.1% 9.1% 7.6% 6.5% 4.7%

Income $10,000 to $19,999 15.0% 13.0% 12.8% 12.8% 12.6% 12.4% 12.3% 11.1% 9.3% 7.9% 5.8%

Income $20,000 to $29,999 13.2% 11.4% 11.2% 11.2% 11.0% 10.9% 10.7% 9.7% 8.1% 6.9% 5.0%

Income $30,000 to $44,999 19.6% 18.5% 18.2% 18.1% 17.9% 17.7% 17.6% 16.0% 13.5% 11.4% 8.2%

Income $45,000 to $59,999 14.9% 17.4% 17.7% 17.8% 18.0% 18.2% 18.5% 19.8% 20.3% 18.6% 13.6%

Income $60,000 to $74,999 9.5% 11.0% 11.2% 11.3% 11.4% 11.6% 11.8% 13.1% 15.8% 18.6% 20.2%

Income $75,000 to $99,999 8.7% 10.1% 10.3% 10.3% 10.5% 10.6% 10.8% 12.0% 14.4% 17.0% 24.1%

Income $100,000 or more 6.8% 7.9% 8.0% 8.1% 8.2% 8.3% 8.4% 9.3% 11.1% 13.1% 18.3%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables Tables-43

Table 4-15

Demographic and Employment Baseline Projections for Economic Impact Area LA-2 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 558.42 585.06 588.41 598.63 608.98 619.45 629.98 672.73 738.07 792.83 902.89

Age Under 19 Years 30.0% 29.0% 28.6% 28.5% 28.6% 28.5% 28.5% 28.6% 28.5% 28.1% 26.9%

Age 20 to 34 20.6% 21.1% 21.4% 21.3% 21.1% 21.0% 20.7% 19.5% 18.0% 18.0% 19.0%

Age 35 to 49 21.8% 19.5% 19.1% 18.7% 18.4% 18.2% 18.2% 18.5% 19.7% 19.4% 17.4%

Age 50 to 64 16.1% 18.6% 19.0% 19.3% 19.5% 19.6% 19.6% 19.2% 17.2% 16.4% 18.3%

Age 65 and over 11.5% 11.9% 12.0% 12.2% 12.5% 12.7% 13.0% 14.1% 16.6% 18.1% 18.4%

Median Age of Population (years) 35.0 35.7 35.7 35.8 36.0 36.1 36.2 37.0 38.1 38.9 39.1

White Population (in thousands) 69.3% 67.6% 67.4% 67.2% 67.1% 67.0% 66.8% 66.2% 65.3% 64.5% 62.8%

Black Population (in thousands) 27.1% 27.9% 27.9% 27.9% 28.0% 28.0% 28.0% 28.1% 28.2% 28.3% 28.5%

Native American Population (in thousands) 0.3% 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

Asian and Pacific Islander Population (in thousands) 1.2% 1.3% 1.4% 1.4% 1.4% 1.4% 1.4% 1.5% 1.6% 1.7% 1.9%

Hispanic or Latino Population (in thousands) 2.1% 2.8% 3.0% 3.1% 3.2% 3.3% 3.4% 3.8% 4.4% 5.0% 6.4%

Male Population (in thousands) 48.7% 48.8% 48.8% 48.8% 48.8% 48.8% 48.9% 49.0% 49.1% 49.1% 49.2%

Total Employment (in thousands of jobs) 297.51 325.85 326.83 339.22 344.71 350.28 355.90 379.08 415.91 448.58 519.72

Farm Employment 1.9% 1.9% 1.8% 1.8% 1.7% 1.7% 1.7% 1.6% 1.5% 1.4% 1.2%

Forestry, Fishing, Related Activities 0.6% 0.6% 0.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6%

Mining 6.9% 7.6% 7.6% 7.6% 7.6% 7.5% 7.5% 7.3% 7.0% 6.8% 6.3%

Utilities 0.2% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2%

Construction 6.7% 6.3% 6.1% 6.0% 6.0% 6.0% 6.0% 6.0% 6.0% 5.9% 5.9%

Manufacturing 6.1% 5.9% 6.0% 6.2% 6.2% 6.1% 6.0% 5.7% 5.3% 4.9% 4.3%

Wholesale Trade 3.7% 3.6% 3.7% 3.9% 3.9% 3.8% 3.8% 3.7% 3.6% 3.5% 3.2%

Retail Trade 11.5% 10.8% 10.8% 10.9% 10.9% 10.9% 10.9% 10.9% 10.9% 10.9% 10.8%

Transportation and Warehousing 3.5% 2.9% 2.9% 2.7% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8%

Information Employment 1.5% 1.2% 1.1% 1.1% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1%

Finance and Insurance 3.4% 3.7% 3.7% 3.5% 3.5% 3.4% 3.4% 3.3% 3.1% 2.9% 2.6%

Real Estate/Rental and Lease 4.0% 4.2% 4.4% 4.3% 4.3% 4.3% 4.3% 4.2% 4.2% 4.1% 4.0%

Professional and Technical Services 4.7% 5.1% 5.2% 5.4% 5.4% 5.4% 5.4% 5.5% 5.6% 5.6% 5.8%

Management 1.1% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3%

Administrative and Waste Services 4.6% 4.8% 4.9% 5.0% 5.0% 5.1% 5.1% 5.2% 5.4% 5.6% 6.0%

Educational Services 1.2% 1.3% 1.3% 1.3% 1.3% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4%

Health Care and Social Assistance 11.2% 11.9% 12.0% 11.9% 12.0% 12.1% 12.3% 12.7% 13.5% 14.1% 15.5%
Tables-44 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-15. Demographic and Employment Baseline Projections for Economic Impact Area LA-2 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Arts, Entertainment, and Recreation 1.5% 1.7% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.7% 1.7% 1.8%

Accommodation and Food Services 6.4% 6.2% 6.3% 6.4% 6.4% 6.4% 6.4% 6.5% 6.7% 6.8% 7.0%

Other Services, Except Public Administration 7.0% 6.7% 6.6% 6.5% 6.6% 6.6% 6.7% 6.9% 7.2% 7.4% 8.0%

Federal Civilian Government 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.5%

Federal Military 0.9% 0.9% 0.9% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7% 0.7% 0.6%

State and Local Government 10.8% 10.5% 10.2% 10.1% 10.1% 10.1% 10.0% 9.9% 9.7% 9.6% 9.2%

Total Earnings (in millions of 2005 dollars) 11,484.00 13,494.78 13,752.84 14,349.59 14,682.89 15,067.24 15,460.41 17,124.71 19,916.17 22,539.61 28,709.70

Farm 0.8% 1.1% 1.2% 1.2% 1.2% 1.2% 1.1% 1.1% 1.0% 1.0% 0.8%

Forestry, Fishing, Related Activities 0.3% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Mining 13.7% 13.4% 13.7% 13.9% 13.6% 13.6% 13.6% 13.5% 13.4% 13.2% 12.9%

Utilities 0.4% 0.4% 0.4% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.4%

Construction 7.1% 7.2% 6.9% 6.7% 6.6% 6.6% 6.5% 6.3% 6.0% 5.8% 5.3%

Manufacturing 7.5% 7.8% 8.0% 8.2% 8.5% 8.5% 8.4% 8.2% 7.9% 7.7% 7.1%

Wholesale Trade 4.7% 4.7% 5.0% 5.3% 5.2% 5.2% 5.2% 5.1% 4.9% 4.8% 4.6%

Retail Trade 7.9% 7.0% 6.9% 6.9% 6.9% 6.8% 6.8% 6.5% 6.1% 5.8% 5.2%

Transportation and Warehousing 4.6% 4.1% 4.1% 4.0% 3.8% 3.8% 3.7% 3.7% 3.6% 3.6% 3.4%

Information 1.7% 1.2% 1.1% 1.2% 1.2% 1.2% 1.2% 1.2% 1.3% 1.3% 1.4%

Finance and Insurance 4.1% 2.8% 2.9% 2.6% 2.7% 2.6% 2.6% 2.5% 2.4% 2.3% 2.0%

Real Estate/Rental and Lease 3.5% 3.6% 3.8% 3.7% 3.7% 3.7% 3.7% 3.6% 3.5% 3.4% 3.2%

Professional and Technical Services 6.0% 6.7% 6.9% 7.2% 7.3% 7.3% 7.4% 7.6% 7.9% 8.2% 8.8%

Management 1.6% 1.8% 1.8% 1.8% 1.9% 1.9% 1.9% 2.0% 2.1% 2.2% 2.4%

Administrative and Waste Services 3.1% 3.3% 3.2% 3.1% 3.1% 3.2% 3.2% 3.3% 3.5% 3.6% 3.9%

Educational Services 0.7% 0.8% 0.8% 0.9% 0.9% 0.9% 0.9% 0.9% 1.0% 1.0% 1.0%

Health Care and Social Assistance 11.3% 12.5% 12.5% 12.4% 12.6% 12.7% 12.9% 13.4% 14.2% 14.9% 16.4%

Arts, Entertainment, and Recreation 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5%

Accommodation and Food Services 2.5% 2.7% 2.8% 2.9% 2.9% 2.9% 2.9% 3.0% 3.1% 3.1% 3.2%

Other Services, Except Public Administration 4.5% 4.5% 4.4% 4.3% 4.3% 4.4% 4.4% 4.5% 4.6% 4.8% 5.1%

Federal Civilian Government 1.2% 1.1% 1.1% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0%

Federal Military 0.9% 0.9% 0.9% 0.9% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%

State and Local Government 11.3% 11.6% 11.0% 10.7% 10.7% 10.7% 10.7% 10.7% 10.6% 10.5% 10.4%

Total Personal Income per Capita (in 2005 dollars) 28,507 32,772 33,321 33,752 33,768 34,047 34,402 36,219 39,557 42,806 50,543

Woods & Poole Economics Wealth Index (U.S. = 100) 72.9 82.8 81.9 81.5 81.1 81.1 81.0 80.7 80.2 79.7 78.7

Persons per Household (in number of people) 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.5 2.5 2.5 2.5
Tables Tables-45

Table 4-15. Demographic and Employment Baseline Projections for Economic Impact Area LA-2 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Mean Household Total Personal Income (in 2005 dollars) 74,766 86,052 87,168 87,764 87,280 87,455 87,855 91,179 99,160 107,670 128,326

Number of Households (in thousands) 212.92 222.81 224.93 230.22 235.61 241.16 246.69 267.23 294.43 315.20 355.62

Income <$10,000 (thousands of households, 2000$) 15.8% 13.6% 13.4% 13.2% 13.0% 12.8% 12.5% 11.7% 9.7% 8.3% 6.0%

Income $10,000 to $19,999 15.2% 13.2% 12.9% 12.7% 12.5% 12.3% 12.2% 11.4% 9.5% 8.2% 6.0%

Income $20,000 to $29,999 13.0% 11.4% 11.1% 10.9% 10.8% 10.7% 10.5% 9.8% 8.3% 7.1% 5.2%

Income $30,000 to $44,999 18.3% 18.2% 18.0% 17.7% 17.6% 17.5% 17.4% 16.8% 14.6% 12.6% 9.1%

Income $45,000 to $59,999 14.0% 16.2% 16.4% 16.6% 16.8% 16.9% 17.1% 17.9% 18.8% 18.6% 15.2%

Income $60,000 to $74,999 9.1% 10.6% 10.8% 11.0% 11.2% 11.4% 11.5% 12.4% 14.8% 17.0% 19.5%

Income $75,000 to $99,999 7.4% 8.7% 8.9% 9.1% 9.2% 9.4% 9.5% 10.2% 12.3% 14.4% 19.9%

Income $100,000 or more 7.1% 8.2% 8.5% 8.7% 8.8% 9.0% 9.1% 9.8% 11.9% 13.8% 19.2%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables-46 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-16

Demographic and Employment Baseline Projections for Economic Impact Area LA-3 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 1,051.06 1,142.41 1,147.53 1,158.87 1,170.43 1,182.18 1,194.01 1,242.03 1,315.00 1,375.33 1,494.59

Age Under 19 Years 29.6% 28.3% 28.0% 27.9% 27.8% 27.8% 27.8% 28.0% 28.1% 27.8% 26.9%

Age 20 to 34 22.3% 22.8% 22.9% 22.9% 22.8% 22.6% 22.3% 20.8% 19.2% 19.1% 20.4%

Age 35 to 49 21.5% 19.6% 19.2% 18.9% 18.6% 18.5% 18.4% 18.9% 19.9% 19.7% 17.3%

Age 50 to 64 16.4% 18.3% 18.6% 18.7% 18.8% 18.9% 18.9% 18.4% 16.8% 16.1% 17.9%

Age 65 and over 10.3% 11.0% 11.3% 11.6% 11.9% 12.2% 12.5% 13.9% 16.1% 17.3% 17.5%

Median Age of Population (years) 34.6 35.7 35.8 35.9 36.1 36.2 36.4 37.2 38.4 39.2 39.6

White Population (in thousands) 65.3% 62.4% 62.2% 61.9% 61.7% 61.4% 61.2% 60.1% 58.6% 57.2% 54.5%

Black Population (in thousands) 29.4% 31.1% 31.1% 31.2% 31.3% 31.4% 31.5% 31.9% 32.4% 32.7% 33.2%

Native American Population (in thousands) 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% 1.3%

Asian and Pacific Islander Population (in thousands) 1.5% 1.7% 1.7% 1.8% 1.8% 1.8% 1.9% 2.0% 2.1% 2.3% 2.6%

Hispanic or Latino Population (in thousands) 2.6% 3.7% 3.9% 4.0% 4.1% 4.2% 4.4% 4.9% 5.7% 6.6% 8.5%

Male Population (in thousands) 48.7% 48.9% 48.8% 48.8% 48.8% 48.8% 48.9% 48.9% 48.9% 48.9% 49.0%

Total Employment (in thousands of jobs) 606.81 669.39 667.49 674.34 684.23 694.25 704.39 746.15 812.61 871.69 1,000.90

Farm Employment 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6% 0.6% 0.6% 0.5% 0.4%

Forestry, Fishing, Related Activities 0.7% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%

Mining 1.5% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% 1.8% 1.7% 1.6% 1.5%

Utilities 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2% 0.2% 0.2% 0.2%

Construction 9.8% 9.0% 8.9% 8.9% 8.8% 8.7% 8.7% 8.5% 8.1% 7.8% 7.2%

Manufacturing 6.8% 6.3% 6.4% 6.5% 6.4% 6.3% 6.2% 5.8% 5.2% 4.8% 4.0%

Wholesale Trade 3.2% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 2.8% 2.7% 2.6% 2.4%

Retail Trade 10.9% 10.3% 10.4% 10.5% 10.5% 10.5% 10.4% 10.3% 10.0% 9.8% 9.2%

Transportation and Warehousing 4.4% 4.4% 4.4% 4.5% 4.5% 4.5% 4.5% 4.5% 4.6% 4.6% 4.7%

Information Employment 1.4% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 0.9%

Finance and Insurance 3.5% 4.0% 4.1% 3.9% 3.8% 3.8% 3.8% 3.7% 3.6% 3.5% 3.3%

Real Estate/Rental and Lease 3.6% 4.1% 4.2% 4.1% 4.1% 4.1% 4.1% 4.1% 4.0% 4.0% 3.9%

Professional and Technical Services 4.8% 5.1% 5.1% 5.2% 5.2% 5.3% 5.3% 5.4% 5.6% 5.7% 5.9%

Management 1.0% 1.2% 1.2% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.4%

Administrative and Waste Services 5.8% 6.1% 6.0% 5.7% 5.8% 5.8% 5.9% 6.1% 6.4% 6.6% 7.1%

Educational Services 1.1% 1.3% 1.4% 1.5% 1.5% 1.6% 1.6% 1.7% 1.8% 2.0% 2.3%

Health Care and Social Assistance 8.8% 9.8% 10.0% 10.0% 10.1% 10.3% 10.4% 10.9% 11.7% 12.4% 13.8%
Tables

Tables-47

Table 4-16. Demographic and Employment Baseline Projections for Economic Impact Area LA-3 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Arts, Entertainment, and Recreation 1.3% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.7% 1.8% 1.8% 1.9%

Accommodation and Food Services 6.6% 6.3% 6.5% 6.6% 6.6% 6.6% 6.7% 6.8% 7.0% 7.2% 7.5%

Other Services, Except Public Administration 6.7% 6.8% 6.8% 6.8% 6.9% 7.0% 7.0% 7.4% 7.9% 8.3% 9.2%

Federal Civilian Government 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6% 0.6% 0.5% 0.5%

Federal Military 0.8% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.8% 0.7% 0.7% 0.6%

State and Local Government 15.6% 14.6% 14.1% 13.9% 13.9% 13.8% 13.7% 13.3% 12.8% 12.3% 11.4%

Total Earnings (in millions of 2005 dollars) 24,055.56 28,740.68 29,009.30 29,302.09 29,854.78 30,546.72 31,253.42 34,234.30 39,202.81 43,846.48 54,710.37

Farm 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2% 0.2% 0.2% 0.2% 0.2%

Forestry, Fishing, Related Activities 0.3% 0.1% 0.1% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Mining 2.6% 2.9% 2.9% 3.0% 3.0% 3.0% 3.0% 2.9% 2.9% 2.8% 2.7%

Utilities 0.7% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4%

Construction 10.3% 11.0% 10.8% 10.7% 10.4% 10.3% 10.2% 9.7% 9.0% 8.4% 7.3%

Manufacturing 12.4% 11.3% 11.5% 11.8% 11.9% 11.8% 11.6% 11.1% 10.4% 9.8% 8.5%

Wholesale Trade 4.4% 4.0% 4.1% 4.2% 4.2% 4.2% 4.2% 4.2% 4.1% 4.0% 3.8%

Retail Trade 7.2% 6.3% 6.3% 6.4% 6.3% 6.3% 6.2% 5.9% 5.4% 5.1% 4.4%

Transportation and Warehousing 6.0% 7.1% 7.3% 7.5% 7.6% 7.6% 7.6% 7.6% 7.6% 7.6% 7.5%

Information 1.7% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.4% 1.4%

Finance and Insurance 4.3% 4.2% 4.4% 4.1% 3.9% 3.9% 3.9% 3.9% 3.9% 3.8% 3.7%

Real Estate/Rental and Lease 2.1% 2.2% 2.3% 2.2% 2.1% 2.1% 2.1% 2.1% 2.0% 2.0% 1.9%

Professional and Technical Services 6.0% 6.4% 6.4% 6.4% 6.5% 6.5% 6.6% 6.9% 7.3% 7.7% 8.4%

Management 1.4% 1.8% 2.0% 2.1% 2.1% 2.1% 2.2% 2.3% 2.6% 2.8% 3.2%

Administrative and Waste Services 3.5% 4.0% 3.7% 3.5% 3.6% 3.7% 3.7% 3.9% 4.3% 4.6% 5.2%

Educational Services 0.6% 0.7% 0.7% 0.8% 0.8% 0.8% 0.8% 0.9% 1.0% 1.1% 1.3%

Health Care and Social Assistance 9.2% 9.4% 9.6% 9.6% 9.8% 9.9% 10.0% 10.6% 11.5% 12.3% 13.9%

Arts, Entertainment, and Recreation 0.7% 0.6% 0.6% 0.6% 0.5% 0.5% 0.5% 0.6% 0.6% 0.6% 0.6%

Accommodation and Food Services 2.7% 2.6% 2.7% 2.7% 2.8% 2.8% 2.8% 2.9% 3.0% 3.1% 3.2%

Other Services, Except Public Administration 4.1% 3.9% 3.9% 3.9% 3.9% 4.0% 4.0% 4.2% 4.4% 4.6% 5.1%

Federal Civilian Government 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1% 1.1% 1.0%

Federal Military 0.9% 1.0% 1.0% 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%

State and Local Government 17.5% 17.1% 16.4% 16.2% 16.3% 16.3% 16.2% 16.1% 15.9% 15.6% 15.1%

Total Personal Income per Capita (in 2005 dollars) 30,406 33,467 33,978 33,975 34,080 34,410 34,810 36,797 40,422 43,957 52,429

Woods & Poole Economics Wealth Index (U.S. = 100) 78.2 87.9 87.2 87.0 87.2 87.3 87.5 87.9 88.2 88.4 88.4

Persons per Household (in number of people) 2.7 2.7 2.7 2.7 2.6 2.6 2.6 2.6 2.6 2.6 2.6

Mean Household Total Personal Income (in 2005 dollars) 81,039 89,653 90,645 90,103 89,862 90,187 90,726 94,626 103,650 113,236 136,682
Tables-48 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-16. Demographic and Employment Baseline Projections for Economic Impact Area LA-3 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Number of Households (in thousands) 394.36 426.46 430.14 436.98 443.89 451.05 458.12 482.99 512.84 533.89 573.30

Income <$10,000 (thousands of households, 2000$) 12.5% 11.1% 10.9% 10.8% 10.7% 10.5% 10.4% 9.6% 8.1% 7.1% 5.2%

Income $10,000 to $19,999 13.3% 11.9% 11.7% 11.6% 11.5% 11.3% 11.1% 10.3% 8.7% 7.6% 5.5%

Income $20,000 to $29,999 12.2% 10.9% 10.7% 10.6% 10.5% 10.4% 10.2% 9.4% 8.0% 7.0% 5.1%

Income $30,000 to $44,999 17.6% 16.3% 16.1% 16.1% 15.9% 15.8% 15.6% 14.5% 12.4% 10.8% 7.9%

Income $45,000 to $59,999 14.6% 16.2% 16.4% 16.5% 16.6% 16.8% 16.9% 17.4% 17.2% 15.7% 11.7%

Income $60,000 to $74,999 11.0% 12.5% 12.7% 12.8% 12.9% 13.1% 13.3% 14.5% 17.1% 19.1% 19.5%

Income $75,000 to $99,999 9.9% 11.1% 11.3% 11.4% 11.5% 11.7% 11.9% 12.9% 15.2% 17.6% 24.4%

Income $100,000 or more 9.0% 10.0% 10.1% 10.2% 10.3% 10.4% 10.6% 11.4% 13.3% 15.2% 20.8%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables Tables-49

Table 4-17

Demographic and Employment Baseline Projections for Economic Impact Area LA-4 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 1,431.31 1,242.69 1,260.01 1,265.95 1,272.16 1,278.59 1,285.13 1,312.22 1,354.31 1,389.22 1,458.44

Age Under 19 Years 28.0% 26.1% 25.8% 25.8% 25.8% 25.8% 25.8% 26.0% 26.0% 25.7% 24.8%

Age 20 to 34 20.6% 21.3% 21.5% 21.4% 21.2% 21.0% 20.6% 19.0% 17.1% 17.1% 18.3%

Age 35 to 49 22.2% 20.1% 19.6% 19.3% 19.2% 19.0% 19.0% 19.7% 20.8% 20.3% 17.4%

Age 50 to 64 17.9% 20.3% 20.6% 20.7% 20.7% 20.8% 20.8% 20.0% 18.1% 17.5% 19.8%

Age 65 and over 11.4% 12.3% 12.5% 12.8% 13.1% 13.5% 13.8% 15.3% 17.9% 19.3% 19.7%

Median Age of Population (years) 36.0 36.7 36.8 36.9 37.0 37.1 37.2 37.8 39.0 39.6 39.7

White Population (in thousands) 53.7% 54.8% 54.5% 54.3% 54.1% 54.0% 53.8% 53.1% 52.1% 51.3% 49.5%

Black Population (in thousands) 38.1% 34.5% 34.6% 34.6% 34.5% 34.4% 34.4% 34.1% 33.7% 33.3% 32.4%

Native American Population (in thousands) 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.5% 0.5% 0.5% 0.5%

Asian and Pacific Islander Population (in thousands) 2.4% 2.8% 2.8% 2.8% 2.9% 2.9% 3.0% 3.1% 3.3% 3.5% 3.7%

Hispanic or Latino Population (in thousands) 5.4% 7.6% 7.7% 7.8% 8.0% 8.2% 8.4% 9.2% 10.3% 11.4% 13.9%

Male Population (in thousands) 48.1% 48.7% 48.7% 48.7% 48.7% 48.8% 48.8% 48.9% 49.0% 49.0% 49.1%

Total Employment (in thousands of jobs) 740.50 744.81 745.46 749.69 756.58 763.49 770.43 798.52 841.58 878.38 954.71

Farm Employment 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2%

Forestry, Fishing, Related Activities 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.6% 0.6%

Mining 1.3% 1.4% 1.4% 1.4% 1.3% 1.3% 1.3% 1.2% 1.1% 1.1% 1.0%

Utilities 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0.3% 0.3% 0.2%

Construction 6.2% 6.7% 6.6% 6.7% 6.6% 6.6% 6.6% 6.5% 6.4% 6.3% 6.1%

Manufacturing 5.6% 5.0% 4.9% 4.9% 4.8% 4.7% 4.6% 4.2% 3.6% 3.2% 2.5%

Wholesale Trade 3.6% 3.3% 3.3% 3.3% 3.3% 3.3% 3.3% 3.2% 3.2% 3.2% 3.2%

Retail Trade 10.0% 9.6% 9.4% 9.4% 9.4% 9.4% 9.4% 9.3% 9.2% 9.2% 9.0%

Transportation and Warehousing 4.1% 4.0% 4.1% 4.2% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.0%

Information Employment 1.6% 1.2% 1.2% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3%

Finance and Insurance 3.9% 4.3% 4.4% 4.1% 4.1% 4.0% 4.0% 3.9% 3.7% 3.5% 3.2%

Real Estate/Rental and Lease 4.0% 4.3% 4.4% 4.2% 4.2% 4.2% 4.2% 4.3% 4.3% 4.4% 4.5%

Professional and Technical Services 5.7% 6.5% 6.5% 6.7% 6.7% 6.8% 6.8% 7.0% 7.2% 7.4% 7.8%

Management 1.1% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2%

Administrative and Waste Services 6.4% 6.7% 6.9% 6.9% 7.0% 7.0% 7.1% 7.4% 7.8% 8.1% 8.8%

Educational Services 3.1% 3.2% 3.3% 3.3% 3.4% 3.4% 3.4% 3.5% 3.6% 3.7% 3.9%
Tables-50 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-17. Demographic and Employment Baseline Projections for Economic Impact Area LA-4 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 8.8% 9.3% 9.4% 9.4% 9.4% 9.4% 9.4% 9.4% 9.5% 9.4% 9.4%

Arts, Entertainment, and Recreation 2.5% 2.5% 2.5% 2.4% 2.5% 2.5% 2.5% 2.6% 2.7% 2.8% 3.1%

Accommodation and Food Services 8.8% 8.9% 9.3% 9.7% 9.7% 9.8% 9.8% 10.0% 10.3% 10.5% 10.9%

Other Services, Except Public Administration 6.5% 6.7% 6.7% 6.6% 6.7% 6.8% 6.8% 7.1% 7.5% 7.8% 8.4%

Federal Civilian Government 2.1% 1.8% 1.7% 1.7% 1.7% 1.7% 1.7% 1.6% 1.6% 1.5% 1.4%

Federal Military 1.4% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1% 1.1% 1.0% 0.9%

State and Local Government 11.9% 11.1% 10.6% 10.4% 10.3% 10.3% 10.2% 9.9% 9.5% 9.1% 8.4%

Total Earnings (in millions of 2005 dollars) 33,666.07 34,271.00 34,751.75 35,008.67 35,826.56 36,464.52 37,112.26 39,803.97 44,161.53 48,109.85 56,971.53

Farm 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1%

Forestry, Fishing, Related Activities 0.2% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1%

Mining 4.4% 3.0% 3.1% 3.1% 3.1% 3.1% 3.0% 2.9% 2.8% 2.6% 2.4%

Utilities 1.2% 1.0% 1.0% 1.0% 1.0% 1.0% 0.9% 0.9% 0.8% 0.8% 0.7%

Construction 6.5% 7.1% 7.1% 7.2% 7.2% 7.2% 7.1% 6.9% 6.5% 6.2% 5.5%

Manufacturing 8.6% 8.9% 8.8% 8.7% 8.4% 8.3% 8.2% 7.6% 6.9% 6.3% 5.2%

Wholesale Trade 5.3% 5.1% 5.2% 5.2% 5.2% 5.2% 5.2% 5.3% 5.4% 5.5% 5.6%

Retail Trade 6.2% 5.8% 5.8% 5.7% 5.6% 5.6% 5.5% 5.3% 5.0% 4.8% 4.3%

Transportation and Warehousing 5.1% 5.3% 5.5% 5.5% 5.4% 5.4% 5.3% 5.2% 5.0% 4.8% 4.5%

Information 1.7% 1.4% 1.5% 1.6% 1.6% 1.6% 1.7% 1.7% 1.7% 1.8% 1.9%

Finance and Insurance 5.1% 4.5% 4.6% 4.3% 4.4% 4.4% 4.3% 4.2% 4.1% 3.9% 3.6%

Real Estate/Rental and Lease 2.6% 1.4% 1.4% 1.3% 1.3% 1.3% 1.3% 1.4% 1.4% 1.4% 1.4%

Professional and Technical Services 8.0% 9.5% 9.8% 10.3% 10.4% 10.5% 10.6% 11.1% 11.8% 12.3% 13.5%

Management 1.8% 1.8% 1.8% 1.8% 1.8% 1.9% 1.9% 2.0% 2.1% 2.2% 2.4%

Administrative and Waste Services 4.0% 4.4% 4.5% 4.5% 4.5% 4.6% 4.6% 4.9% 5.3% 5.6% 6.3%

Educational Services 2.2% 2.5% 2.6% 2.7% 2.7% 2.7% 2.7% 2.8% 3.0% 3.2% 3.4%

Health Care and Social Assistance 8.7% 9.5% 9.4% 9.2% 9.2% 9.2% 9.3% 9.4% 9.5% 9.6% 9.7%

Arts, Entertainment, and Recreation 2.1% 1.7% 1.8% 1.8% 1.9% 1.9% 1.9% 2.0% 2.1% 2.2% 2.4%

Accommodation and Food Services 4.4% 4.8% 4.9% 5.0% 5.0% 5.1% 5.1% 5.2% 5.4% 5.5% 5.8%

Other Services, Except Public Administration 3.7% 3.8% 3.8% 3.8% 3.8% 3.8% 3.8% 4.0% 4.2% 4.3% 4.7%

Federal Civilian Government 4.2% 3.7% 3.6% 3.5% 3.5% 3.5% 3.5% 3.5% 3.6% 3.6% 3.7%

Federal Military 1.8% 1.7% 1.7% 1.6% 1.6% 1.6% 1.6% 1.7% 1.7% 1.7% 1.8%

State and Local Government 12.1% 12.7% 12.3% 12.1% 12.0% 12.0% 12.0% 11.8% 11.6% 11.5% 11.1%

Total Personal Income per Capita (in 2005 dollars) 31,461 37,558 38,141 38,473 38,887 39,232 39,672 41,926 46,044 50,030 59,481

Woods & Poole Economics Wealth Index (U.S. = 100) 77.3 93.0 92.3 92.6 92.3 92.3 92.4 92.3 92.0 91.6 90.4

Persons per Household (in number of people) 2.7 2.6 2.6 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Tables Tables-51

Table 4-17. Demographic and Employment Baseline Projections for Economic Impact Area LA-4 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Mean Household Total Personal Income (in 2005 dollars) 84,130 96,574 97,610 97,943 98,476 98,800 99,398 103,829 113,973 124,630 150,391

Number of Households (in thousands) 535.25 483.28 492.35 497.27 502.36 507.71 512.92 529.88 547.13 557.67 576.83

Income <$10,000 (thousands of households, 2000$) 12.9% 10.7% 10.5% 10.3% 10.2% 10.0% 9.9% 9.1% 7.7% 6.7% 5.0%

Income $10,000 to $19,999 13.7% 11.6% 11.4% 11.2% 11.0% 10.9% 10.8% 9.9% 8.5% 7.5% 5.6%

Income $20,000 to $29,999 13.0% 11.1% 10.9% 10.8% 10.6% 10.5% 10.4% 9.6% 8.3% 7.3% 5.5%

Income $30,000 to $44,999 17.6% 15.1% 14.9% 14.8% 14.6% 14.5% 14.4% 13.5% 11.7% 10.4% 7.9%

Income $45,000 to $59,999 13.6% 15.3% 15.4% 15.6% 15.6% 15.7% 15.7% 15.7% 14.8% 13.5% 10.4%

Income $60,000 to $74,999 10.0% 11.9% 12.1% 12.2% 12.4% 12.6% 12.7% 13.8% 15.7% 16.5% 15.0%

Income $75,000 to $99,999 9.2% 11.4% 11.5% 11.7% 11.9% 12.0% 12.2% 13.2% 15.6% 17.8% 23.1%

Income $100,000 or more 10.1% 13.1% 13.3% 13.5% 13.7% 13.9% 14.0% 15.2% 17.9% 20.4% 27.4%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables-52 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-18

Demographic and Employment Baseline Projections for Economic Impact Area MS-1 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 483.49 482.30 486.36 489.21 492.17 495.21 498.29 510.96 530.49 546.67 578.72

Age Under 19 Years 28.4% 27.7% 27.4% 27.3% 27.2% 27.3% 27.3% 27.6% 27.6% 27.1% 26.4%

Age 20 to 34 19.8% 19.9% 20.1% 20.1% 20.0% 19.8% 19.6% 18.6% 17.7% 17.7% 18.8%

Age 35 to 49 22.0% 20.3% 19.9% 19.6% 19.3% 19.0% 18.9% 19.0% 19.1% 18.9% 17.5%

Age 50 to 64 17.8% 19.4% 19.7% 19.8% 19.9% 20.0% 20.1% 19.7% 18.4% 17.5% 18.1%

Age 65 and over 12.0% 12.7% 12.9% 13.2% 13.6% 13.8% 14.1% 15.2% 17.3% 18.8% 19.2%

Median Age of Population (years) 36.4 37.4 37.5 37.7 37.8 37.9 38.0 38.4 39.0 39.5 39.6

White Population (in thousands) 75.8% 73.9% 73.2% 73.0% 72.8% 72.7% 72.5% 71.7% 70.6% 69.6% 67.7%

Black Population (in thousands) 18.7% 19.3% 19.8% 19.9% 19.9% 20.0% 20.1% 20.3% 20.8% 21.1% 21.7%

Native American Population (in thousands) 0.5% 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4%

Asian and Pacific Islander Population (in thousands) 2.0% 2.1% 2.1% 2.1% 2.1% 2.2% 2.2% 2.2% 2.3% 2.3% 2.3%

Hispanic or Latino Population (in thousands) 3.0% 4.2% 4.4% 4.5% 4.6% 4.7% 4.8% 5.2% 5.9% 6.5% 7.9%

Male Population (in thousands) 49.7% 49.9% 49.9% 49.9% 49.9% 49.8% 49.8% 49.8% 49.8% 49.8% 49.7%

Total Employment (in thousands of jobs) 238.83 240.12 242.03 244.21 246.33 248.45 250.60 259.29 272.69 284.28 308.79

Farm Employment 1.4% 1.4% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2% 1.2%

Forestry, Fishing, Related Activities 0.8% 0.7% 0.7% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.9% 0.9%

Mining 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Utilities 0.9% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7% 0.7%

Construction 7.5% 8.1% 8.0% 8.4% 8.4% 8.4% 8.4% 8.4% 8.5% 8.5% 8.4%

Manufacturing 9.5% 9.5% 9.3% 9.3% 9.2% 9.0% 8.9% 8.2% 7.4% 6.7% 5.5%

Wholesale Trade 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.3% 1.3% 1.3%

Retail Trade 10.9% 10.3% 10.4% 10.4% 10.4% 10.4% 10.4% 10.3% 10.1% 9.9% 9.4%

Transportation and Warehousing 2.4% 2.3% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.3% 2.3% 2.4%

Information Employment 1.4% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.8% 0.8%

Finance and Insurance 2.5% 2.9% 3.0% 2.9% 2.9% 2.9% 2.9% 2.9% 2.8% 2.8% 2.7%

Real Estate/Rental and Lease 3.1% 3.3% 3.4% 3.3% 3.3% 3.3% 3.4% 3.4% 3.5% 3.6% 3.8%

Professional and Technical Services 3.8% 4.1% 4.0% 3.9% 4.0% 4.0% 4.0% 4.0% 4.1% 4.2% 4.3%

Management 0.5% 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4%

Administrative and Waste Services 5.4% 6.6% 6.8% 6.9% 7.0% 7.2% 7.3% 8.0% 9.1% 10.1% 12.3%

Educational Services 0.5% 0.7% 0.8% 0.9% 0.9% 1.0% 1.0% 1.1% 1.2% 1.4% 1.7%
Tables Tables-53

Table 4-18. Demographic and Employment Baseline Projections for Economic Impact Area MS-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 6.2% 6.4% 6.3% 6.1% 6.2% 6.2% 6.3% 6.4% 6.7% 6.8% 7.1%

Arts, Entertainment, and Recreation 2.2% 2.2% 2.1% 2.1% 2.1% 2.1% 2.1% 2.2% 2.2% 2.3% 2.4%

Accommodation and Food Services 12.1% 10.4% 10.7% 10.7% 10.6% 10.6% 10.6% 10.4% 10.2% 9.9% 9.4%

Other Services, Except Public Administration 5.5% 5.0% 4.9% 4.9% 4.9% 4.9% 4.9% 5.0% 5.2% 5.3% 5.4%

Federal Civilian Government 3.9% 3.9% 3.9% 3.9% 3.9% 3.8% 3.8% 3.7% 3.5% 3.4% 3.1%

Federal Military 5.7% 5.5% 5.5% 5.3% 5.3% 5.3% 5.2% 5.1% 4.9% 4.7% 4.3%

State and Local Government 12.3% 13.0% 12.9% 12.9% 12.9% 12.9% 12.9% 12.8% 12.7% 12.5% 12.2%

Total Earnings (in millions of 2005 dollars) 9,318.99 9,982.21 9,882.08 10,040.86 10,210.79 10,389.92 10,571.81 11,327.83 12,553.09 13,665.84 16,177.84

Farm 0.3% 0.0% 0.0% 0.0% 0.2% 0.2% 0.2% 0.2% 0.2% 0.1% 0.1%

Forestry, Fishing, Related Activities 0.5% 0.3% 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.5%

Mining 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Utilities 2.1% 1.7% 1.7% 1.7% 1.8% 1.8% 1.8% 1.8% 1.8% 1.9% 1.9%

Construction 6.0% 7.6% 7.6% 8.0% 8.0% 7.9% 7.9% 7.7% 7.4% 7.2% 6.7%

Manufacturing 15.4% 16.5% 16.4% 16.5% 16.2% 16.0% 15.8% 15.0% 13.8% 12.8% 10.9%

Wholesale Trade 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6%

Retail Trade 7.0% 6.3% 6.3% 6.2% 6.1% 6.1% 6.0% 5.7% 5.3% 5.0% 4.4%

Transportation and Warehousing 2.3% 2.2% 2.3% 2.4% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0%

Information 1.4% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 1.0% 1.0% 1.0%

Finance and Insurance 2.2% 2.4% 2.4% 2.3% 2.3% 2.3% 2.3% 2.3% 2.3% 2.3% 2.3%

Real Estate/Rental and Lease 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 1.0%

Professional and Technical Services 4.6% 5.1% 5.0% 5.0% 5.0% 5.0% 5.1% 5.2% 5.5% 5.6% 6.0%

Management 0.6% 0.6% 0.7% 0.7% 0.7% 0.7% 0.8% 0.8% 0.8% 0.8% 0.9%

Administrative and Waste Services 3.1% 4.0% 4.1% 4.2% 4.4% 4.5% 4.6% 5.1% 5.9% 6.7% 8.5%

Educational Services 0.3% 0.4% 0.5% 0.6% 0.6% 0.6% 0.6% 0.7% 0.8% 0.9% 1.2%

Health Care and Social Assistance 6.7% 6.7% 6.7% 6.7% 6.7% 6.8% 6.8% 7.0% 7.4% 7.6% 8.1%

Arts, Entertainment, and Recreation 1.5% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.3%

Accommodation and Food Services 8.0% 6.1% 6.4% 6.4% 6.4% 6.4% 6.4% 6.3% 6.2% 6.0% 5.7%

Other Services, Except Public Administration 3.3% 3.2% 3.2% 3.1% 3.1% 3.2% 3.2% 3.2% 3.3% 3.3% 3.4%

Federal Civilian Government 8.4% 7.9% 8.0% 7.9% 7.9% 7.9% 7.9% 7.9% 8.0% 7.9% 7.9%

Federal Military 10.2% 10.0% 9.8% 9.2% 9.3% 9.4% 9.4% 9.5% 9.7% 9.8% 10.1%

State and Local Government 13.2% 14.4% 14.2% 14.0% 14.0% 14.1% 14.1% 14.2% 14.3% 14.4% 14.4%

Total Personal Income per Capita (in 2005 dollars) 27,436 29,962 29,903 29,997 30,093 30,348 30,672 32,334 35,391 38,370 45,492

Woods & Poole Economics Wealth Index (U.S. = 100) 67.8 74.7 73.7 73.5 73.5 73.6 73.6 73.6 73.3 73.1 72.4

Persons per Household (in number of people) 2.6 2.7 2.7 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.7
Tables-54 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-18. Demographic and Employment Baseline Projections for Economic Impact Area MS-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Mean Household Total Personal Income (in 2005 dollars) 72,253 79,963 79,462 79,331 79,207 79,477 79,955 83,484 91,624 100,243 121,307

Number of Households (in thousands) 183.59 180.72 183.02 184.98 186.99 189.10 191.15 197.90 204.91 209.25 217.03

Income <$10,000 (thousands of households, 2000$) 10.9% 9.6% 9.5% 9.3% 9.2% 9.1% 8.9% 8.2% 6.9% 5.9% 4.2%

Income $10,000 to $19,999 13.3% 11.7% 11.6% 11.4% 11.2% 11.1% 10.9% 10.0% 8.4% 7.2% 5.1%

Income $20,000 to $29,999 13.9% 12.1% 12.0% 11.8% 11.6% 11.4% 11.3% 10.3% 8.6% 7.4% 5.2%

Income $30,000 to $44,999 20.5% 18.9% 18.8% 18.6% 18.4% 18.2% 17.9% 16.5% 13.9% 11.8% 8.4%

Income $45,000 to $59,999 15.7% 17.9% 18.1% 18.4% 18.6% 18.8% 19.0% 20.0% 20.3% 18.7% 13.7%

Income $60,000 to $74,999 10.2% 11.9% 12.0% 12.2% 12.4% 12.6% 12.7% 13.9% 16.8% 19.4% 20.9%

Income $75,000 to $99,999 8.5% 9.9% 10.0% 10.1% 10.3% 10.4% 10.6% 11.6% 14.0% 16.4% 23.6%

Income $100,000 or more 6.9% 8.0% 8.1% 8.2% 8.3% 8.5% 8.6% 9.4% 11.3% 13.3% 19.1%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables Tables-55

Table 4-19

Demographic and Employment Baseline Projections for Economic Impact Area TX-1 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 1,643.97 1,799.29 1,827.28 1,858.83 1,890.78 1,923.07 1,955.52 2,086.93 2,286.87 2,453.62 2,786.67

Age Under 19 Years 35.4% 34.9% 34.7% 34.5% 34.3% 34.2% 34.1% 33.7% 32.6% 32.2% 31.1%

Age 20 to 34 21.4% 20.5% 20.6% 20.5% 20.5% 20.4% 20.3% 20.0% 20.4% 20.1% 20.1%

Age 35 to 49 18.9% 18.7% 18.5% 18.5% 18.4% 18.2% 18.1% 17.9% 17.0% 16.8% 17.0%

Age 50 to 64 13.7% 15.1% 15.1% 15.2% 15.3% 15.4% 15.4% 15.3% 15.4% 15.2% 14.6%

Age 65 and over 10.6% 10.9% 11.1% 11.3% 11.5% 11.8% 12.0% 13.0% 14.7% 15.7% 17.3%

Median Age of Population (years) 33.8 35.7 35.4 35.5 35.6 35.8 35.9 36.4 37.0 37.5 37.8

White Population (in thousands) 18.2% 16.1% 15.8% 15.6% 15.3% 15.1% 14.8% 13.9% 12.7% 11.7% 10.0%

Black Population (in thousands) 1.2% 1.2% 1.3% 1.3% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2%

Native American Population (in thousands) 0.2% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1%

Asian and Pacific Islander Population 

(in thousands)

0.9% 1.0% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1%

Hispanic or Latino Population (in thousands) 79.5% 81.6% 81.7% 82.0% 82.2% 82.5% 82.7% 83.6% 84.9% 85.9% 87.7%

Male Population (in thousands) 48.8% 48.8% 48.9% 48.9% 48.9% 48.9% 48.8% 48.8% 48.7% 48.6% 48.4%

Total Employment (in thousands of jobs) 728.92 805.32 819.02 833.79 848.38 863.18 878.21 940.55 1,041.20 1,132.22 1,336.29

Farm Employment 1.7% 1.6% 1.6% 1.6% 1.6% 1.5% 1.5% 1.4% 1.2% 1.1% 0.8%

Forestry, Fishing, Related Activities 1.2% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 0.9% 0.9%

Mining 1.8% 2.1% 2.1% 2.1% 2.1% 2.1% 2.0% 1.9% 1.8% 1.7% 1.5%

Utilities 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3%

Construction 7.2% 6.3% 6.0% 6.3% 6.2% 6.2% 6.1% 6.0% 5.7% 5.5% 5.0%

Manufacturing 4.0% 3.2% 3.1% 3.1% 3.0% 3.0% 2.9% 2.7% 2.5% 2.2% 1.8%

Wholesale Trade 2.8% 2.6% 2.6% 2.7% 2.7% 2.6% 2.6% 2.5% 2.4% 2.3% 2.1%

Retail Trade 12.0% 11.6% 11.6% 11.7% 11.7% 11.7% 11.7% 11.7% 11.6% 11.6% 11.4%

Transportation and Warehousing 3.3% 3.3% 3.4% 3.6% 3.6% 3.6% 3.6% 3.6% 3.7% 3.7% 3.8%

Information Employment 1.2% 1.0% 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.8%

Finance and Insurance 3.1% 3.9% 4.0% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 4.0% 4.0%

Real Estate/Rental and Lease 3.0% 3.0% 2.9% 2.8% 2.8% 2.8% 2.8% 2.7% 2.6% 2.6% 2.4%

Professional and Technical Services 3.3% 3.3% 3.3% 3.4% 3.4% 3.5% 3.5% 3.6% 3.7% 3.8% 3.9%

Management 0.2% 0.3% 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.5% 0.5% 0.6%

Administrative and Waste Services 5.4% 5.6% 5.7% 5.7% 5.8% 5.8% 5.8% 6.0% 6.2% 6.4% 6.8%

Educational Services 0.9% 1.0% 1.1% 1.1% 1.2% 1.2% 1.2% 1.2% 1.3% 1.4% 1.6%
Tables-56 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-19. Demographic and Employment Baseline Projections for Economic Impact Area TX-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 15.6% 17.4% 17.7% 17.5% 17.7% 17.9% 18.1% 18.9% 20.1% 21.1% 23.1%

Arts, Entertainment, and Recreation 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1%

Accommodation and Food Services 7.2% 7.4% 7.6% 7.8% 7.8% 7.8% 7.9% 8.0% 8.1% 8.3% 8.4%

Other Services, Except Public Administration 6.5% 6.0% 5.9% 5.8% 5.8% 5.8% 5.8% 5.9% 6.0% 6.0% 6.2%

Federal Civilian Government 1.7% 2.0% 2.0% 2.0% 1.9% 1.9% 1.9% 1.8% 1.7% 1.6% 1.4%

Federal Military 1.3% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 0.9% 0.8% 0.8% 0.6%

State and Local Government 15.1% 15.0% 14.6% 14.1% 14.1% 14.0% 13.9% 13.5% 13.0% 12.5% 11.6%

Total Earnings (in millions of 2005 dollars) 24,168.27 27,416.26 28,511.77 29,436.42 30,105.83 30,921.50 31,758.31 35,328.26 41,419.56 47,267.21 61,514.93

Farm 1.6% 1.2% 1.2% 1.2% 1.1% 1.1% 1.1% 1.0% 0.9% 0.8% 0.6%

Forestry, Fishing, Related Activities 0.7% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.4%

Mining 3.6% 3.8% 3.9% 3.9% 3.8% 3.7% 3.7% 3.6% 3.4% 3.3% 3.0%

Utilities 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% 0.8% 0.8% 0.8%

Construction 7.5% 6.9% 6.7% 7.0% 6.9% 6.8% 6.7% 6.3% 5.8% 5.3% 4.5%

Manufacturing 5.9% 4.9% 4.8% 4.7% 4.7% 4.7% 4.6% 4.4% 4.1% 3.8% 3.3%

Wholesale Trade 4.2% 3.9% 4.0% 4.2% 4.1% 4.1% 4.1% 4.0% 3.9% 3.7% 3.5%

Retail Trade 8.8% 8.2% 8.4% 8.7% 8.7% 8.6% 8.5% 8.1% 7.6% 7.2% 6.4%

Transportation and Warehousing 3.6% 4.1% 4.4% 4.6% 4.6% 4.6% 4.6% 4.5% 4.5% 4.4% 4.3%

Information 1.5% 1.2% 1.1% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.3% 1.3%

Finance and Insurance 3.4% 3.2% 3.2% 3.1% 3.1% 3.1% 3.1% 3.1% 3.2% 3.3% 3.4%

Real Estate/Rental and Lease 1.4% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.2% 1.1% 1.1% 1.0%

Professional and Technical Services 4.6% 3.9% 4.0% 4.1% 4.2% 4.2% 4.3% 4.4% 4.7% 5.0% 5.4%

Management 0.1% 0.4% 0.4% 0.4% 0.3% 0.3% 0.3% 0.4% 0.5% 0.6% 0.8%

Administrative and Waste Services 3.0% 3.3% 3.4% 3.5% 3.5% 3.6% 3.6% 3.7% 3.9% 4.1% 4.4%

Educational Services 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% 0.9% 0.9% 1.1%

Health Care and Social Assistance 14.9% 17.2% 17.2% 16.9% 17.2% 17.4% 17.6% 18.6% 20.1% 21.4% 23.9%

Arts, Entertainment, and Recreation 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

Accommodation and Food Services 3.4% 3.5% 3.6% 3.7% 3.8% 3.8% 3.8% 3.9% 4.0% 4.0% 4.1%

Other Services, Except Public Administration 4.5% 4.3% 4.2% 4.2% 4.2% 4.2% 4.2% 4.3% 4.3% 4.4% 4.4%

Federal Civilian Government 4.9% 5.5% 5.4% 5.3% 5.3% 5.3% 5.2% 5.1% 5.0% 4.8% 4.5%

Federal Military 2.8% 2.4% 2.5% 2.5% 2.4% 2.4% 2.4% 2.4% 2.3% 2.3% 2.2%

State and Local Government 17.8% 18.4% 17.9% 17.3% 17.3% 17.3% 17.3% 17.1% 16.9% 16.7% 16.1%

Total Personal Income per Capita (in 2005 dollars) 20,907 23,000 23,616 23,864 23,983 24,222 24,503 25,892 28,489 31,102 37,653

Woods & Poole Economics Wealth Index 

(U.S. = 100)

67.9 76.7 77.2 78.2 78.3 78.8 79.2 80.6 82.0 82.9 83.8
Tables Tables-57

Table 4-19. Demographic and Employment Baseline Projections for Economic Impact Area TX-1 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Persons per Household (in number of people) 3.2 3.3 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.3

Mean Household Total Personal Income 

(in 2005 dollars)

67,317 74,865 76,593 77,019 77,040 77,417 77,962 81,618 90,088 99,282 122,725

Number of Households (in thousands) 510.57 552.77 563.40 575.95 588.62 601.67 614.61 662.04 723.19 768.65 854.98

Income <$10,000 (thousands of households, 

2000$)

15.7% 13.7% 13.3% 13.1% 12.9% 12.7% 12.5% 11.4% 9.4% 8.1% 5.9%

Income $10,000 to $19,999 17.7% 15.5% 15.0% 14.7% 14.5% 14.3% 14.1% 12.9% 10.6% 9.1% 6.7%

Income $20,000 to $29,999 15.0% 13.4% 13.0% 12.7% 12.5% 12.4% 12.2% 11.1% 9.2% 7.8% 5.7%

Income $30,000 to $44,999 18.8% 20.0% 20.2% 20.2% 20.2% 20.3% 20.3% 20.0% 18.0% 15.5% 11.4%

Income $45,000 to $59,999 12.4% 14.2% 14.6% 14.9% 15.1% 15.3% 15.5% 16.8% 19.2% 20.3% 17.9%

Income $60,000 to $74,999 7.7% 8.7% 9.0% 9.2% 9.3% 9.5% 9.6% 10.5% 12.7% 14.8% 18.9%

Income $75,000 to $99,999 6.6% 7.5% 7.7% 7.9% 8.0% 8.1% 8.2% 9.0% 10.8% 12.6% 17.3%

Income $100,000 or more 6.1% 7.0% 7.2% 7.3% 7.4% 7.6% 7.7% 8.4% 10.1% 11.8% 16.3%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables-58 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-20

Demographic and Employment Baseline Projections for Economic Impact Area TX-2 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 581.75 626.91 633.41 644.11 654.92 665.83 676.78 721.00 787.94 843.49 953.91

Age Under 19 Years 29.6% 29.1% 29.0% 29.0% 29.1% 29.1% 29.1% 29.3% 29.3% 29.2% 29.0%

Age 20 to 34 18.6% 18.3% 18.5% 18.4% 18.4% 18.4% 18.3% 18.0% 18.6% 18.9% 19.7%

Age 35 to 49 22.3% 20.6% 20.1% 19.8% 19.4% 19.2% 19.0% 18.6% 17.5% 17.2% 17.4%

Age 50 to 64 17.1% 19.2% 19.4% 19.6% 19.6% 19.7% 19.6% 18.9% 17.4% 16.4% 15.3%

Age 65 and over 12.4% 12.8% 13.0% 13.2% 13.5% 13.7% 14.0% 15.1% 17.1% 18.2% 18.5%

Median Age of Population (years) 39.1 40.5 40.5 40.6 40.5 40.5 40.4 40.1 39.2 38.2 36.5

White Population (in thousands) 58.3% 54.0% 53.3% 52.7% 52.0% 51.4% 50.8% 48.4% 44.7% 41.6% 35.6%

Black Population (in thousands) 9.3% 10.2% 10.3% 10.4% 10.5% 10.5% 10.6% 10.8% 11.3% 11.6% 12.4%

Native American Population (in thousands) 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3%

Asian and Pacific Islander Population (in thousands) 2.4% 3.4% 3.4% 3.5% 3.6% 3.6% 3.7% 4.0% 4.3% 4.5% 4.9%

Hispanic or Latino Population (in thousands) 29.6% 32.1% 32.6% 33.1% 33.6% 34.1% 34.6% 36.5% 39.4% 41.9% 46.7%

Male Population (in thousands) 50.2% 50.2% 50.2% 50.1% 50.1% 50.1% 50.1% 50.1% 50.0% 49.9% 49.6%

Total Employment (in thousands of jobs) 287.62 305.55 312.26 318.88 323.58 328.37 333.21 353.34 385.94 415.44 481.57

Farm Employment 7.4% 6.9% 6.8% 6.6% 6.6% 6.6% 6.5% 6.3% 6.0% 5.7% 5.2%

Forestry, Fishing, Related Activities 1.2% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 1.0%

Mining 2.4% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 3.0% 3.0% 2.9%

Utilities 1.1% 1.0% 0.9% 1.0% 1.0% 1.0% 1.0% 1.0% 0.9% 0.9% 0.9%

Construction 9.6% 8.9% 9.2% 10.2% 10.2% 10.2% 10.2% 10.2% 10.2% 10.2% 10.2%

Manufacturing 9.7% 8.8% 8.8% 8.8% 8.8% 8.7% 8.6% 8.3% 7.8% 7.3% 6.4%

Wholesale Trade 2.7% 2.7% 2.8% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0%

Retail Trade 11.3% 11.2% 11.0% 11.0% 11.0% 11.1% 11.1% 11.2% 11.3% 11.4% 11.5%

Transportation and Warehousing 2.8% 2.7% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6% 2.5% 2.5% 2.3%

Information Employment 0.8% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6% 0.6% 0.6%

Finance and Insurance 3.4% 4.5% 4.6% 4.5% 4.5% 4.6% 4.6% 4.8% 5.2% 5.5% 6.2%

Real Estate/Rental and Lease 3.4% 3.6% 3.6% 3.5% 3.5% 3.5% 3.6% 3.6% 3.8% 3.9% 4.2%

Professional and Technical Services 3.9% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.2% 4.2%

Management 0.2% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.4%

Administrative and Waste Services 4.6% 4.2% 4.4% 4.5% 4.5% 4.6% 4.6% 4.7% 4.8% 4.9% 5.2%

Educational Services 0.9% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.1% 1.2% 1.3%
Tables Tables-59

Table 4-20. Demographic and Employment Baseline Projections for Economic Impact Area TX-2 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 7.4% 8.2% 8.3% 8.2% 8.3% 8.4% 8.5% 8.8% 9.3% 9.7% 10.6%

Arts, Entertainment, and Recreation 1.2% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2%

Accommodation and Food Services 5.6% 5.9% 5.9% 6.0% 6.0% 6.1% 6.1% 6.4% 6.8% 7.2% 8.1%

Other Services, Except Public Administration 6.5% 5.9% 5.9% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8%

Federal Civilian Government 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.3%

Federal Military 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.3%

State and Local Government 12.9% 13.0% 12.5% 11.9% 11.8% 11.7% 11.5% 11.0% 10.2% 9.5% 8.1%

Total Earnings (in millions of 2005 dollars) 10,282.28 11,289.29 11,744.88 12,021.21 12,041.32 12,321.87 12,608.68 13,821.27 15,850.49 17,753.16 22,210.77

Farm 3.5% 2.0% 1.9% 1.9% 1.8% 1.8% 1.8% 1.7% 1.6% 1.6% 1.4%

Forestry, Fishing, Related Activities 0.7% 0.5% 0.5% 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4%

Mining 4.3% 4.1% 4.1% 4.0% 4.1% 4.1% 4.2% 4.3% 4.5% 4.6% 4.9%

Utilities 2.7% 2.8% 2.7% 2.8% 2.5% 2.5% 2.5% 2.6% 2.8% 2.9% 3.1%

Construction 11.7% 11.3% 11.8% 13.2% 13.5% 13.4% 13.3% 13.0% 12.6% 12.2% 11.5%

Manufacturing 20.2% 18.8% 19.1% 19.2% 19.2% 19.2% 19.2% 19.0% 18.6% 18.3% 17.4%

Wholesale Trade 3.5% 4.5% 4.9% 5.3% 4.4% 4.4% 4.4% 4.5% 4.6% 4.7% 4.9%

Retail Trade 8.1% 7.9% 7.9% 7.9% 8.0% 8.0% 7.9% 7.7% 7.4% 7.2% 6.7%

Transportation and Warehousing 3.2% 3.4% 3.4% 3.3% 3.2% 3.2% 3.2% 3.1% 3.0% 2.8% 2.6%

Information 0.8% 0.7% 0.7% 0.6% 0.7% 0.7% 0.7% 0.6% 0.6% 0.6% 0.6%

Finance and Insurance 3.0% 3.1% 3.0% 2.8% 3.2% 3.2% 3.3% 3.5% 3.8% 4.0% 4.7%

Real Estate/Rental and Lease 1.5% 2.1% 2.2% 2.2% 1.8% 1.8% 1.8% 1.8% 1.9% 1.9% 2.0%

Professional and Technical Services 3.9% 4.1% 4.0% 4.0% 3.8% 3.9% 3.9% 4.0% 4.1% 4.3% 4.5%

Management 0.1% 0.2% 0.2% 0.1% 0.4% 0.4% 0.5% 0.5% 0.6% 0.6% 0.8%

Administrative and Waste Services 2.5% 2.5% 2.5% 2.5% 2.7% 2.7% 2.7% 2.8% 2.9% 3.1% 3.3%

Educational Services 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.5% 0.5% 0.5% 0.6%

Health Care and Social Assistance 6.8% 7.9% 7.8% 7.6% 7.9% 7.9% 8.0% 8.4% 9.1% 9.6% 10.7%

Arts, Entertainment, and Recreation 0.4% 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

Accommodation and Food Services 2.2% 2.5% 2.5% 2.5% 2.4% 2.4% 2.5% 2.6% 2.8% 2.9% 3.4%

Other Services, Except Public Administration 5.2% 4.9% 4.8% 4.7% 4.8% 4.8% 4.8% 4.8% 4.8% 4.8% 4.7%

Federal Civilian Government 0.9% 0.9% 0.9% 0.8% 0.9% 0.9% 0.9% 0.9% 0.8% 0.8% 0.8%

Federal Military 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6%

State and Local Government 13.9% 14.4% 13.6% 12.7% 12.9% 12.8% 12.7% 12.3% 11.6% 11.1% 9.9%

Total Personal Income per Capita (in 2005 dollars) 29,554 32,870 34,011 34,322 34,024 34,254 34,549 36,104 39,100 42,144 49,755

Woods & Poole Economics Wealth Index (U.S. = 100) 78.4 87.7 88.4 88.6 87.7 87.8 88.0 88.8 89.9 90.8 92.8
Tables-60 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-20. Demographic and Employment Baseline Projections for Economic Impact Area TX-2 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Persons per Household (in number of people) 2.7 2.8 2.8 2.8 2.8 2.7 2.7 2.7 2.7 2.7 2.8

Mean Household Total Personal Income (in 2005 dollars) 81,195 91,618 94,435 94,838 93,574 93,741 94,123 97,474 105,974 115,407 139,471

Number of Households (in thousands) 211.75 224.92 228.13 233.11 238.13 243.30 248.42 267.05 290.72 308.02 340.30

Income <$10,000 (thousands of households, 2000$) 9.6% 8.3% 8.0% 7.9% 7.8% 7.7% 7.6% 6.9% 5.9% 5.1% 3.7%

Income $10,000 to $19,999 12.9% 11.2% 10.8% 10.6% 10.6% 10.4% 10.3% 9.4% 8.1% 7.0% 5.2%

Income $20,000 to $29,999 12.9% 11.2% 10.9% 10.7% 10.7% 10.5% 10.3% 9.5% 8.2% 7.2% 5.3%

Income $30,000 to $44,999 17.5% 16.2% 15.8% 15.5% 15.5% 15.3% 15.1% 14.0% 12.1% 10.5% 7.8%

Income $45,000 to $59,999 14.3% 15.3% 15.3% 15.3% 15.3% 15.3% 15.3% 15.6% 14.8% 13.3% 9.6%

Income $60,000 to $74,999 11.2% 12.9% 13.4% 13.6% 13.7% 13.9% 14.1% 15.1% 16.7% 17.4% 15.7%

Income $75,000 to $99,999 10.9% 12.7% 13.1% 13.4% 13.4% 13.7% 13.9% 15.0% 17.3% 20.0% 26.3%

Income $100,000 or more 10.5% 12.2% 12.7% 13.0% 13.0% 13.2% 13.4% 14.5% 16.8% 19.4% 26.4%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

ource: Woods & Poole Economics, Inc., 2013.
Tables Tables-61

Table 4-21

Demographic and Employment Baseline Projections for Economic Impact Area TX-3 

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Total Population (in thousands) 5,518.20 6,202.21 6,309.03 6,442.79 6,577.78 6,713.83 6,850.35 7,400.96 8,234.48 8,927.83 10,309.09

Age Under 19 Years 30.7% 30.3% 30.1% 30.1% 30.1% 30.1% 30.1% 30.0% 29.7% 29.5% 29.1%

Age 20 to 34 22.2% 21.8% 21.8% 21.7% 21.6% 21.5% 21.4% 20.9% 21.1% 21.1% 21.2%

Age 35 to 49 22.8% 21.3% 21.0% 20.8% 20.5% 20.4% 20.3% 20.0% 19.2% 18.7% 18.5%

Age 50 to 64 15.8% 17.5% 17.7% 17.8% 17.9% 17.9% 17.9% 17.4% 16.4% 15.9% 15.5%

Age 65 and over 8.5% 9.1% 9.3% 9.6% 9.8% 10.1% 10.4% 11.6% 13.6% 14.7% 15.7%

Median Age of Population (years) 37.4 38.2 38.3 38.4 38.5 38.5 38.6 38.7 38.8 38.8 38.4

White Population (in thousands) 45.8% 41.7% 41.3% 40.6% 40.0% 39.3% 38.7% 36.2% 32.8% 30.0% 25.1%

Black Population (in thousands) 17.6% 17.8% 17.6% 17.5% 17.4% 17.3% 17.2% 16.7% 16.0% 15.4% 14.2%

Native American Population (in thousands) 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3%

Asian and Pacific Islander Population 

(in thousands)

5.7% 6.5% 6.5% 6.7% 6.8% 6.9% 7.1% 7.6% 8.3% 8.9% 10.1%

Hispanic or Latino Population (in thousands) 30.6% 33.8% 34.2% 34.9% 35.5% 36.1% 36.7% 39.1% 42.5% 45.3% 50.4%

Male Population (in thousands) 49.8% 49.8% 49.8% 49.8% 49.8% 49.8% 49.8% 49.7% 49.6% 49.5% 49.2%

Total Employment (in thousands of jobs) 3,218.66 3,591.39 3,674.80 3,780.47 3,852.39 3,925.65 4,000.29 4,312.97 4,827.44 5,301.86 6,392.23

Farm Employment 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4%

Forestry, Fishing, Related Activities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

Mining 2.8% 3.1% 3.1% 3.1% 3.1% 3.1% 3.1% 3.1% 3.0% 3.0% 2.9%

Utilities 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4%

Construction 8.0% 7.6% 7.3% 7.5% 7.6% 7.6% 7.6% 7.7% 7.8% 7.9% 8.1%

Manufacturing 7.4% 6.9% 7.0% 7.1% 7.0% 6.9% 6.8% 6.4% 5.8% 5.3% 4.5%

Wholesale Trade 4.5% 4.4% 4.5% 4.7% 4.7% 4.7% 4.7% 4.7% 4.7% 4.7% 4.7%

Retail Trade 10.2% 9.4% 9.4% 9.4% 9.4% 9.4% 9.4% 9.3% 9.1% 9.0% 8.7%

Transportation and Warehousing 4.3% 4.2% 4.3% 4.4% 4.4% 4.3% 4.3% 4.2% 4.1% 4.0% 3.8%

Information Employment 1.5% 1.2% 1.2% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 0.9% 0.8%

Finance and Insurance 4.5% 5.4% 5.5% 5.3% 5.3% 5.3% 5.3% 5.3% 5.4% 5.4% 5.4%

Real Estate/Rental and Lease 4.1% 4.2% 4.2% 4.0% 4.0% 4.0% 4.0% 4.0% 4.0% 3.9% 3.9%

Professional and Technical Services 7.8% 7.9% 7.9% 8.1% 8.1% 8.1% 8.1% 8.3% 8.4% 8.5% 8.8%

Management 0.6% 0.8% 0.8% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%

Administrative and Waste Services 7.4% 7.3% 7.5% 7.6% 7.6% 7.7% 7.7% 7.9% 8.1% 8.3% 8.7%

Educational Services 1.6% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.8% 1.8% 1.8% 1.8%
Tables-62 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-21. Demographic and Employment Baseline Projections for Economic Impact Area TX-3 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Health Care and Social Assistance 8.2% 9.1% 9.2% 9.1% 9.2% 9.3% 9.4% 9.8% 10.5% 11.0% 12.1%

Arts, Entertainment, and Recreation 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5%

Accommodation and Food Services 6.5% 6.7% 6.8% 6.8% 6.9% 6.9% 6.9% 7.0% 7.2% 7.3% 7.6%

Other Services, Except Public Administration 6.0% 5.8% 5.8% 5.7% 5.7% 5.7% 5.8% 5.8% 5.9% 6.0% 6.1%

Federal Civilian Government 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.8% 0.7% 0.7% 0.6%

Federal Military 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0.3%

State and Local Government 10.3% 9.9% 9.7% 9.3% 9.3% 9.2% 9.2% 8.9% 8.6% 8.3% 7.8%

Total Earnings (in millions of 2005 dollars) 186,536.20 201,343.67 209,492.83 216,460.02 222,664.44 228,935.92 235,382.66 263,020.74 310,620.91 356,739.41 470,279.90

Farm 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.0% 0.0%

Forestry, Fishing, Related Activities 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1%

Mining 12.3% 8.2% 8.3% 8.1% 7.9% 8.0% 8.0% 8.1% 8.2% 8.3% 8.3%

Utilities 1.6% 1.7% 1.7% 1.6% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7%

Construction 8.2% 8.2% 7.9% 8.1% 8.1% 8.1% 8.0% 7.9% 7.7% 7.5% 7.1%

Manufacturing 11.7% 11.0% 11.3% 11.6% 11.5% 11.3% 11.2% 10.7% 9.9% 9.3% 8.3%

Wholesale Trade 6.2% 7.0% 7.4% 7.9% 7.9% 8.0% 8.0% 8.1% 8.2% 8.3% 8.4%

Retail Trade 5.2% 5.0% 4.9% 4.9% 4.8% 4.8% 4.7% 4.5% 4.2% 4.0% 3.5%

Transportation and Warehousing 5.6% 6.0% 6.4% 6.7% 6.7% 6.6% 6.6% 6.3% 6.0% 5.7% 5.2%

Information 1.7% 1.3% 1.3% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1% 1.1% 1.0%

Finance and Insurance 5.5% 5.3% 5.3% 5.0% 5.0% 5.0% 5.0% 5.1% 5.1% 5.2% 5.2%

Real Estate/Rental and Lease 2.4% 1.7% 1.6% 1.4% 1.5% 1.5% 1.5% 1.5% 1.4% 1.4% 1.4%

Professional and Technical Services 10.8% 11.9% 11.9% 12.0% 12.1% 12.2% 12.3% 12.7% 13.2% 13.6% 14.5%

Management 0.6% 1.5% 1.7% 1.9% 1.9% 1.9% 2.0% 2.1% 2.3% 2.5% 2.9%

Administrative and Waste Services 4.4% 4.6% 4.7% 4.7% 4.8% 4.8% 4.9% 5.0% 5.2% 5.4% 5.8%

Educational Services 1.0% 1.1% 1.0% 1.0% 1.0% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2%

Health Care and Social Assistance 6.5% 7.7% 7.5% 7.3% 7.3% 7.4% 7.5% 7.9% 8.5% 8.9% 9.9%

Arts, Entertainment, and Recreation 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6%

Accommodation and Food Services 2.3% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2.5% 2.5% 2.6% 2.6%

Other Services, Except Public Administration 3.1% 3.4% 3.3% 3.3% 3.3% 3.3% 3.3% 3.3% 3.3% 3.3% 3.4%

Federal Civilian Government 1.7% 1.7% 1.6% 1.5% 1.5% 1.5% 1.5% 1.5% 1.4% 1.3% 1.2%

Federal Military 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

State and Local Government 8.3% 9.0% 8.6% 8.2% 8.1% 8.1% 8.1% 7.9% 7.8% 7.6% 7.3%

Total Personal Income per Capita (in 2005 dollars) 39,184 39,270 40,486 40,855 41,434 41,679 42,021 43,955 47,917 52,096 62,960
Tables Tables-63

Table 4-21. Demographic and Employment Baseline Projections for Economic Impact Area TX-3 (continued)

2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040

Woods & Poole Economics Wealth Index 

(U.S. = 100)

84.6 92.1 92.7 93.3 93.1 93.1 93.0 92.8 92.6 92.7 93.4

Persons per Household (in number of people) 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.9

Mean Household Total Personal Income 

(in 2005 dollars)

107,917 111,833 114,840 115,321 116,414 116,532 116,965 121,262 132,684 145,707 180,074

Number of Households (in thousands) 2,003.61 2,177.90 2,224.21 2,282.53 2,341.14 2,401.28 2,461.04 2,682.72 2,973.74 3,192.07 3,604.44

Income <$10,000 (thousands of households, 

2000$)

8.7% 8.0% 7.8% 7.7% 7.6% 7.5% 7.4% 6.9% 6.0% 5.3% 4.1%

Income $10,000 to $19,999 10.9% 10.1% 9.9% 9.8% 9.6% 9.5% 9.4% 8.8% 7.6% 6.8% 5.2%

Income $20,000 to $29,999 11.9% 11.1% 10.8% 10.7% 10.6% 10.5% 10.4% 9.7% 8.4% 7.6% 5.8%

Income $30,000 to $44,999 16.7% 15.7% 15.4% 15.2% 15.0% 14.9% 14.7% 13.8% 12.1% 10.8% 8.3%

Income $45,000 to $59,999 14.0% 14.2% 14.3% 14.3% 14.2% 14.3% 14.3% 14.1% 12.9% 11.6% 8.9%

Income $60,000 to $74,999 10.9% 11.6% 11.8% 11.9% 12.0% 12.1% 12.3% 12.9% 14.2% 14.6% 12.8%

Income $75,000 to $99,999 11.4% 12.4% 12.7% 12.8% 13.0% 13.2% 13.3% 14.3% 16.3% 18.0% 21.4%

Income $100,000 or more 15.5% 16.9% 17.3% 17.5% 17.8% 18.0% 18.2% 19.6% 22.5% 25.2% 33.6%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; and persons per household calculated using total population/number of households for the EIA. 

Source: Woods & Poole Economics, Inc., 2013.
Tables-64 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-22

Peak Employment Projected from Cumulative OCS Programs as a Percent of Total Employment

EIA 

Low Case High Case

Peak 

Annual Peak Year Baseline in Peak Year Percent Peak Annual Peak Year Baseline in Peak Year Percent

Texas (TX)

TX-1 6,274 2030 1,132,220 0.55% 9,795 2031 1,151,200 0.85%

TX-2 2,556 2031 421,620 0.61% 4,154 2031 421,620 0.99%

TX-3 53,117 2030 5,301,860 1.00% 78,387 2031 5,402,030 1.45%

Louisiana (LA)

LA-1 3,459 2030 220,300 1.57% 5,700 2031 223,080 2.56%

LA-2 10,023 2030 448,580 2.23% 15,733 2031 455,290 3.46%

LA-3 13,076 2030 871,690 1.50% 20,868 2031 883,890 2.36%

LA-4 6,753 2030 878,380 0.77% 10,803 2031 885,790 1.22%

Florida (FL)

FL-1 1,843 2031 633,130 0.29% 2,983 2031 633,130 0.47%

FL-2 3,630 2031 409,990 0.89% 5,910 2031 409,990 1.44%

FL-3 3,191 2031 2,550,120 0.13% 5,216 2031 2,550,120 0.20%

FL-4 2,284 2031 4,873,290 0.05% 3,729 2031 4,873,290 0.08%

Alabama (AL)

AL-1 4,344 2030 482,560 0.90% 7,106 2031 488,970 1.45%

Mississippi (MS)

MS-1 3,369 2030 284,280 1.19% 5,450 2031 286,640 1.90%

Sources: Peak employment output from BOEM’s economic impact model (MAG-PLAN).

Baseline employment projections based on Woods & Poole Economics, Inc. (2013).
Tables Tables-65

Table 4-23

Baseline Employment Projections (in thousands) by Economic Impact Area

Model 

Year

Calendar

Year TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

2010 805.32 305.55 3,591.39 177.41 325.85 669.39 744.81 240.12 373.38 473.21 322.32 1,842.54 3,351.08

2011 819.02 312.26 3,674.80 175.82 326.83 667.49 745.46 242.03 378.73 483.35 323.02 1,880.65 3,452.11

2012 833.79 318.88 3,780.47 175.74 339.22 674.34 749.69 244.21 379.89 489.04 324.07 1,915.18 3,548.46

2013 848.38 323.58 3,852.39 177.96 344.71 684.23 756.58 246.33 385.02 495.84 328.11 1,945.11 3,610.06

2014 863.18 328.37 3,925.65 180.22 350.28 694.25 763.49 248.45 390.21 502.71 332.19 1,975.41 3,672.52

2015 878.21 333.21 4,000.29 182.51 355.90 704.39 770.43 250.60 395.45 509.67 336.31 2,006.07 3,735.84

2016 893.45 338.13 4,076.29 184.81 361.59 714.65 777.41 252.75 400.77 516.72 340.49 2,037.10 3,800.03

2017 908.92 343.12 4,153.75 187.14 367.36 725.01 784.42 254.92 406.14 523.84 344.72 2,068.51 3,865.12

2018 924.62 348.20 4,232.62 189.51 373.19 735.51 791.46 257.09 411.60 531.06 349.01 2,100.28 3,931.07

2019 940.55 353.34 4,312.97 191.90 379.08 746.15 798.52 259.29 417.11 538.36 353.35 2,132.46 3,997.92

2020 956.70 358.59 4,394.82 194.33 385.04 756.89 805.62 261.49 422.71 545.75 357.75 2,165.03 4,065.70

2021 973.03 363.90 4,478.12 196.79 391.03 767.72 812.68 263.69 428.36 553.20 362.20 2,197.79 4,133.93

2022 989.64 369.29 4,563.01 199.27 397.10 778.70 819.81 265.92 434.08 560.75 366.71 2,231.04 4,203.30

2023 1,006.54 374.76 4,649.50 201.79 403.28 789.84 827.01 268.16 439.87 568.41 371.27 2,264.80 4,273.84

2024 1,023.72 380.31 4,737.64 204.33 409.54 801.14 834.26 270.42 445.75 576.17 375.89 2,299.07 4,345.56

2025 1,041.20 385.94 4,827.44 206.92 415.91 812.61 841.58 272.69 451.70 584.04 380.57 2,333.86 4,418.49

2026 1,058.80 391.67 4,918.80 209.53 422.25 824.09 848.82 274.97 457.71 591.96 385.32 2,368.66 4,491.42

2027 1,076.69 397.48 5,011.89 212.17 428.68 835.74 856.11 277.27 463.80 599.99 390.13 2,403.98 4,565.56

2028 1,094.89 403.38 5,106.74 214.85 435.22 847.56 863.47 279.59 469.97 608.12 395.00 2,439.83 4,640.92

2029 1,113.40 409.37 5,203.38 217.56 441.85 859.54 870.89 281.92 476.23 616.37 399.93 2,476.22 4,717.53

2030 1,132.22 415.44 5,301.86 220.30 448.58 871.69 878.38 284.28 482.56 624.72 404.92 2,513.15 4,795.40

2031 1,151.20 421.62 5,402.03 223.08 455.29 883.89 885.79 286.64 488.97 633.13 409.99 2,550.12 4,873.29

2032 1,170.49 427.89 5,504.09 225.88 462.11 896.25 893.27 289.03 495.46 641.66 415.12 2,587.65 4,952.44

2033 1,190.12 434.26 5,608.08 228.73 469.02 908.79 900.81 291.43 502.04 650.30 420.32 2,625.72 5,032.88

2034 1,210.07 440.71 5,714.04 231.61 476.04 921.50 908.41 293.85 508.70 659.05 425.58 2,664.35 5,114.62

2035 1,230.35 447.27 5,821.99 234.53 483.16 934.39 916.07 296.30 515.46 667.93 430.90 2,703.56 5,197.70
Tables-66 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-23. Baseline Employment Projections (in thousands) by Economic Impact Area (continued)

Model 

Year

Calendar

Year TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

2036 1,250.85 453.93 5,931.82 237.48 490.26 947.33 923.67 298.75 522.28 676.87 436.32 2,742.85 5,280.79

2037 1,271.68 460.68 6,043.72 240.47 497.46 960.44 931.34 301.23 529.20 685.93 441.81 2,782.71 5,365.21

2038 1,292.86 467.54 6,157.72 243.50 504.77 973.74 939.06 303.73 536.21 695.11 447.36 2,823.15 5,450.98

2039 1,314.40 474.50 6,273.88 246.57 512.19 987.23 946.85 306.25 543.31 704.41 452.98 2,864.18 5,538.12

2040 1,336.29 481.57 6,392.23 249.67 519.72 1,000.90 954.71 308.79 550.51 713.84 458.68 2,905.81 5,626.66

2041 1,358.55 488.74 6,512.81 252.81 527.36 1,014.76 962.62 311.35 557.80 723.39 464.44 2,948.04 5,716.61

2042 1,381.17 496.01 6,635.67 256.00 535.11 1,028.81 970.61 313.93 565.19 733.08 470.28 2,990.89 5,807.99

2043 1,404.18 503.40 6,760.84 259.22 542.97 1,043.06 978.66 316.53 572.67 742.89 476.19 3,034.35 5,900.84

2044 1,427.57 510.89 6,888.38 262.49 550.95 1,057.50 986.78 319.16 580.26 752.83 482.18 3,078.45 5,995.18

2045 1,451.35 518.50 7,018.32 265.79 559.05 1,072.14 994.97 321.80 587.95 762.91 488.24 3,123.19 6,091.02

2046 1,475.52 526.22 7,150.71 269.14 567.26 1,086.99 1,003.22 324.47 595.73 773.12 494.38 3,168.58 6,188.39

2047 1,500.10 534.05 7,285.60 272.53 575.60 1,102.04 1,011.54 327.16 603.62 783.47 500.59 3,214.63 6,287.32

2048 1,525.08 542.00 7,423.04 275.96 584.06 1,117.30 1,019.93 329.88 611.62 793.95 506.89 3,261.35 6,387.83

2049 1,550.48 550.07 7,563.07 279.43 592.64 1,132.77 1,028.39 332.61 619.72 804.58 513.26 3,308.75 6,489.95

2050 1,576.31 558.26 7,705.73 282.95 601.35 1,148.46 1,036.92 335.37 627.93 815.35 519.71 3,356.84 6,593.70

2051 1,602.56 566.57 7,851.09 286.51 610.19 1,164.36 1,045.52 338.15 636.25 826.26 526.25 3,405.62 6,699.11

2052 1,629.26 575.01 7,999.20 290.12 619.16 1,180.48 1,054.20 340.95 644.67 837.32 532.86 3,455.12 6,806.21

2053 1,656.39 583.57 8,150.09 293.77 628.26 1,196.83 1,062.94 343.78 653.21 848.53 539.56 3,505.33 6,915.01

2054 1,683.98 592.26 8,303.83 297.47 637.49 1,213.40 1,071.76 346.63 661.86 859.88 546.34 3,556.28 7,025.56

2055 1,712.03 601.07 8,460.48 301.22 646.86 1,230.21 1,080.65 349.51 670.63 871.39 553.21 3,607.96 7,137.87

Notes: Actual Woods & Poole data for 2010 through 2020, 2025, 2030, 2035, and 2040. 

Missing estimates through 2040 calculated using average annual growth rate for the 5-year period; projections after 2040 calculated using the average annual growth rate 

from 2035 to 2040.

Source: Woods & Poole Economics, Inc., 2013. 
Tables Tables-67

Table 4-24

Existing Coastal Infrastructure Related to OCS Activities in the Gulf of Mexico

Infrastructure Texas Louisiana Mississippi Alabama Florida Total

Pipeline Landfalls1 13 109 3 4 0 129

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

Refineries2 18 15 1 3 0 37

Petrochemical Plants2 126 66 2 9 13 216

1 Source: USDOI, BOEMRE, 2011.

2 Source: Dismukes, 2011.

Table 4-25

Gulf of Mexico Counties and Parishes with Concentrated Levels 

of Oil- and Gas-Related Infrastructure

Low Concentration Medium Concentration High Concentration

County/Parish State County/Parish State County/Parish State

Escambia FL Bay FL Mobile AL

Manatee FL Hillsborough FL Cameron LA

Lafayette LA Calcasieu LA Jefferson LA

St. John the Baptist LA Iberia LA Lafourche LA

West Baton Rouge LA Orleans LA Plaquemines LA 

Harrison MS St. Bernard LA St. Mary LA

Aransas TX St. Charles LA Brazoria TX

Cameron TX St. James LA Galveston TX

Fort Bend TX Vermilion LA Harris TX

Matagorda TX Jackson MS Jefferson TX

Montgomery TX Calhoun TX

Orange TX Nueces TX

San Patricio TX

Source: Kaplan et al., 2011.
Tables-68 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table 4-26

Deepwater Horizon Waste Landfill Destination

Landfill Name and Location 

Percent 

Minority 

Living within 

1-Mile 

Radius of 

Site

Total 

Population 

Living within 

1-Mile Radius 

of Site 

(2000 Census)

Percentage 

of Total 

Deepwater 

Horizon Liquid 

Waste 

Collected

Percentage 

of Total 

Deepwater 

Horizon

Solid Waste 

Collected

Liquid Environmental Solutions, Mobile, LA 95.80% 4,257 13.17% 0.00%

Oil Recovery Company, Mobile, LA 93.90% 3,238 0.08% 0.00%

Cliff Berry, Inc. – Miami, FL 92.80% 24,768 >0.58% 0.00%

River Birch Industries Landfill, Avondale, LA 92.20% 167 16.99% 8.67%

Jefferson Parish Waste Management, Avondale, LA 91.40% 120 0.00% 0.02%

Sunbelt Crushing, Mobile, LA 76.80% 3,173 0.00% 0.29%

Chemical Waste Management, Emelle, LA 75.20% 33 1.02% 0.00%

WM Springhill Regional Landfill, Campbelton, FL 74.30% 109 0.00% 23.67%

Allied Waste/BFI Colonial Landfill, Sorrento, LA 74.10% 153 0.00% 21.98%

Allied Waste Recycling Center, Metairie, LA 63.50% 14,420 0.00% 0.06%

WH Chastang Landfill, Mount Vernon, AL 62.50% 123 0.00% 8.93%

Clearview Landfill Lake, MS 50.90% 55 0.44% 14.92%

Cliff Berry, Inc. – Tampa, FL 50.50% 1,817 >0.58% 0.00%

Apex Environmental Services, Theodore, AL 50.40% 383 17.44% 0.00%

Newpark Environmental Services Site Code 5102, 

Morgan City, LA

35.90% 4,237 2.74% 0.00%

Liquid Environmental Solutions, Mobile, AL 63.30% 4,257 13.17% 0.00%

Newpark Environmental Mud Facility, Venice, LA 50.00% 2 10.90% 0.00%

Oil Recovery Company, Mobile, AL 41.70% 3,238 0.08% 0.00%

Chemical Waste Management, Emelle, LA 36.40% 33 1.02% 0.00%

Newpark Environmental Services Site Code 2913, 

Fourchon, LA

33.30% 3 30.14% 0.00%

Vacco Marine, Houma, LA 29.20% 525 0.16% 0.00%

River Birch Industries Landfill, Avondale, LA 28.10% 167 16.99% 8.67%

Jefferson Parish Waste Management, Avondale, LA 26.70% 120 0.00% 0.02%

Apex Environmental Services, Theodore, AL 26.20% 383 17.44% 0.00%

Allied Waste/BFI Colonial Landfill, Sorrento, LA 25.00% 153 0.00% 21.98%

WM Pecan Grove, Pass Christian, MS 14.40% 290 0.00% 3.28%

Baldwin County Magnolia Landfill, Summerdale, AL 13.70% 446 0.00% 11.18%

MBO LLC (Lacassine Oilfield Services), Lacassine, 

LA

12.90% 85 3.82% 0.00%

Coast Guard Rd Sanitary Landfill, Sorrento, LA 0.00% 0 0.00% 8.05%

Source: British Petroleum, 2010.
Tables Tables-69

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Investigations & Compliance Analysis (CG-INV), Washington, DC.

U.S. Dept. of Labor. Bureau of Labor Statistics. 2013. Quarterly census of employment and wages for 

2008-2012. Internet website: http://www.bls.gov/cew/. Accessed December 1, 2010.

U.S. Dept. of the Army. Corps of Engineers. 2002. United States of America ocean dumping report for 

calendar year 2001 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2001.pdf. Accessed June 19, 2013. 

U.S. Dept. of the Army. Corps of Engineers. 2003. United States of America ocean dumping report for 

calendar year 2002 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2002.pdf. Accessed June 19, 2013.

U.S. Dept. of the Army. Corps of Engineers. 2004. United States of America ocean dumping report for 

calendar year 2003 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2003.pdf. Accessed June 19, 2013.

U.S. Dept. of the Army. Corps of Engineers. 2005. United States of America ocean dumping report for 

calendar year 2004 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2004.pdf. Accessed June 19, 2013.

U.S. Dept. of the Army. Corps of Engineers. 2006. United States of America ocean dumping report for 

calendar year 2005 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2005.pdf. Accessed June 19, 2013.
Tables-70 Central Planning Area Lease Sales 235, 241, and 247 EIS

U.S. Dept. of the Army. Corps of Engineers. 2007. United States of America ocean dumping report for

calendar year 2006 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2006.pdf. Accessed June 19, 2013.

U.S. Dept. of the Army. Corps of Engineers. 2008. United States of America ocean dumping report for 

calendar year 2007 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2007.pdf. Accessed June 19, 2013.

U.S. Dept. of the Army. Corps of Engineers. 2009. United States of America ocean dumping report for 

calendar year 2008 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2008.pdf. Accessed June 19, 2013.

U.S. Dept. of the Army. Corps of Engineers. 2010a. United States of America ocean dumping report for 

calendar year 2009 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2009.pdf. Accessed June 19, 2013.

U.S. Dept. of the Army. Corps of Engineers. 2010b. United States of America ocean dumping report for 

calendar year 2010 dredged material. U.S. Dept. of the Army, Corps of Engineers, Headquarters, 

Washington, DC. Internet website: http://el.erdc.usace.army.mil/odd/Download_Sites/LC_files/

LC_2010.pdf. Accessed June 19, 2013.

U.S. Dept. of the Interior. Bureau of Ocean Energy Management, Regulation and Enforcement. 2011. 

Technical Information Management System. Pipelines (June 2011) and OCS spill database (May 

2011). U.S. Dept. of the Interior, Bureau of Ocean Energy Management, Regulation and 

Enforcement, Gulf of Mexico OCS Region, New Orleans, LA.

U.S. Department of Interior. Bureau of Safety and Environmental Enforcement. 2013. Spills -- statistics 

and summaries through 2012. Internet website: http://www.bsee.gov/Inspection-and-Enforcement/

Accidents-and-Incidents/Spills.aspx. Accessed August 8, 2013.

U.S. Dept. of Transportation. Maritime Administration (MARAD). 2013. Vessel calls at U.S. ports by 

vessel type. Internet website: http://www.marad.dot.gov/documents/

US_Port_Calls_by_Vessel_Type.xls. Current as of March 28, 2013. Accessed June 19, 2013.

Woods & Poole Economics, Inc. 2013. The 2013 complete economic and demographic data source 

(CEDDS) on CD-ROM.
APPENDIX A 

AIR QUALITY OFFSHORE MODELING ANALYSIS

Air Quality Offshore Modeling Analysis A-3 

APPENDIX A. AIR QUALITY OFFSHORE MODELING ANALYSIS

Introduction

This Appendix discusses the coastal dispersion modeling analysis and the potential impacts of 

offshore emission from a CPA proposed action to onshore air quality. The latest version of the Offshore 

and Coastal Dispersion Model (Version 5.0, dated May 16, 2005) was used to calculate impacts. The 

objective of the analysis was to determine if the impacts from the proposed actions would significantly 

affect the environment, particularly public health and public welfare.

Background 

The Clean Air Act, which was last amended in 1990, requires the U.S. Environmental Protection 

Agency (USEPA) to set National Ambient Air Quality Standards (NAAQS, [40 CFR part 50]) for 

pollutants considered harmful to public health and the environment. The USEPA has set NAAQS for six 

principal pollutants, which are called “criteria” pollutants. These pollutants are carbon monoxide, lead, 

nitrogen dioxide, ozone, particle pollution (listed as PM2.5 and PM10), and sulfur dioxide.

The NAAQS were developed to protect the public health and welfare while allowing for an adequate 

margin of safety. Primary NAAQS protect the public health including sensitive subpopulations such as 

infants and the elderly. Secondary NAAQS standards protect public welfare such as the prevention of 

aquatic acidification, plant leaf damage, or visibility impairment. Thus, for NEPA evaluation purposes, it 

is reasonable to presume that concentrations of emissions from offshore activities that, following transport 

to shore, which do not cause exceedances of the NAAQS and are below BOEM’s maximum allowable 

increases, will have minimal impacts to onshore air quality. 

The Outer Continental Shelf Lands Act requires the Secretary of the Interior to promulgate and 

administer regulations for compliance with the NAAQS to the extent that the authorized activities 

significantly affect the air quality of any state. These regulations apply in the area of the proposed actions 

and alternatives.

BOEM-regulated pollutants include carbon monoxide (CO), suspended particulates, sulfur dioxide 

(SO2), nitrogen oxides (NOx), and volatile organic compounds (VOC’s). The original NAAQS particulate 

standard was for total suspended particulates (TSP’s), which BOEM adopted. This standard has been 

replaced by USEPA in their regulations with the PM10 and PM2.5 (particulate matter equal to or below 

10 μm and equal to or below 2.5μm in size) because these specific size classifications better define the 

size range that has the greatest environmental impact. BOEM’s regulations use the TSP designation, but 

for purposes of this NEPA analysis, BOEM determined levels of PM10 and PM2.5 so that our data are 

compatible with USEPA’s data. This is just one example of where the U.S. Environmental Protection 

Agency’s NAAQS and BOEM’s regulations may be somewhat different. As another example, BOEM’s 

regulations employ 3-hour, 24-hour, and annual standards while USEPA has set 1-hour standards to limit 

pollutant spikes that are not detectable when concentrations are averaged over a longer time period. Both 

types of particulate designations are included in this Appendix. 

For OCS oil and gas activities in the GOM west of 87.5° W. longitude, BOEM has developed 

evaluation criteria and screening tools. Refer to Chapter 4.2.1.1 of Gulf of Mexico OCS Oil and Gas 

Lease Sales: 2013-2014; Western Planning Area Lease Sale 233; Central Planning Area Lease Sale 231, 

Final Supplemental Environmental Impact Statement (WPA 233/CPA 231 Supplemental EIS).

According to the Clean Air Act Amendments, the air quality in national parks, national wilderness 

areas, national monuments, and national seashores (42 U.S.C. § 7470) must be preserved. The Clean Air 

Act Amendments establish Class I and II areas, where emissions of particulate matter and sulfur dioxide 

are to be restricted. The restrictions are most severe in Class I areas and are progressively less restrictive 

in Class II areas. In the Gulf of Mexico, the Breton National Wilderness Area, 95 mi (153 km) from the 

proposed CPA lease sale area, is the Class I area most likely to be impacted by OCS activity. At the 

Breton National Wilderness Area, if modeled emissions from offshore activities result below the U.S. 

Environmental Protection Agency’s SIL’s, it is reasonable to presume for NEPA evaluation purposes that 

they have negligible impacts to the air quality on this pristine Federal area.
A-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

Offshore Coastal Dispersion Model

The Offshore and Coastal Dispersion Model Version 5 (OCD 5 model) was developed by USEPA in 

conjunction with BOEM’s predecessor agency, the Minerals Management Service, in the late 1980’s, and 

the model was formally approved for use in January 1988. The OCD 5 model is a coastal dispersion 

model that was formulated to estimate shoreline concentrations resulting from releases taking place from 

offshore petroleum drilling platforms. The developers suggest that direct turbulence measurements be 

used to estimate the dispersion parameters over water. As the plume comes ashore, dispersion is 

estimated for the effect of transport over land using traditional techniques (Turner and Schulze, 2007).

The OCD 5 model input data comprises source-specific data as well as meteorological data. The 

source-specific data includes location of activities, emission rate information for all sources associated 

with activities at the given location, and stack parameters for each source. The model requires both overland and over-water meteorological data to determine the potential onshore impacts of the offshore 

operations. These data include overland surface characteristics such as surface roughness and over-water 

data such as water temperature, over-water air temperature, over-water dew point, over-water wind speed, 

and over-water wind direction. These data are usually obtained from overland meteorological stations, 

radiosonde observations, and offshore buoys closest to emission sources. 

The model parameters are arranged to consider onshore locations (receptors) at which the OCD 5 

model will predict the pollutant concentrations of the modeled emission sources. Receptors are identified 

on the shoreline and at nearby Class I areas. Although the OCD 5 model does not include algorithms for 

parameters such as regional haze and acid deposition, its relatively simpler data processing makes it an 

efficient model for use in predicting pollutant impacts from offshore sources.

The OCD 5 model was chosen to analyze the proposed impacts because it performs best when 

meteorological data is collected over the water. The OCD 5 model was approved for use by the Director 

of the Minerals Management Service (currently BOEM), and it is listed as an approved air quality model 

in Appendix W of 40 CFR part 51. More recently, BOEM’s Director approved the use of the CaliforniaPUFF model (CALPUFF), another approved dispersion model listed in Appendix W of 40 CFR part 51. 

However, the OCD 5 model was chosen because BOEM continues to believe it is the more conservative 

of the two models.

The OCD model does not include a simulation of onshore ozone levels. Several prior studies have 

demonstrated that OCS activities have only a small contribution to onshore ozone formation. Because the 

offshore activities’ contribution to onshore ozone have been shown to be very small, BOEM chose to run 

the OCD model. The studies that support this decision include the Gulf of Mexico Air Quality Study

(Systems Applications International et al., 1995), in which this Agency used the Urban Airshed Model 

(UAM-V) to assess the potential impacts of OCS activity in the WPA/CPA on USEPA -designated ozone 

nonattainment areas in urban onshore Texas and Louisiana. Relative to onshore contributors, OCS 

contributors to onshore ozone formation were low. The Gulf of Mexico Air Quality Study was followed 

by a study in 2000 that used the year 2000 Gulfwide emissions to assess the OCS contribution to onshore 

ozone in the Houston/Brazoria/Galveston region of Texas. The Comprehensive Air Quality Model with 

extensions (CAMx) was used to model contribution during an August 2000 ozone episode (Yarwood

et al., 2004). The OCS contributions to ozone exceedances were minor. Yarwood et al. (2004) used a 

photochemical model to analyze the Year 2000 Gulfwide Emissions Inventory (GWEI) and selected the 

Houston-Galveston-Brazoria nonattainment area since it has the most severe ozone problem in the Gulf of 

Mexico region (System Applications International et al., 1995). One of the main relevant findings in 

Yarwood et al. (2004) is as follow: “The average impact of the year 2000 GWEI emissions on 8-hour 

ozone levels above 85 ppb in Houston area is 0.2 ppb; although larger impacts may occur over the Gulf of 

Mexico.” Haney et al. (2008) performed a modeling investigation using the year 2000 and year 2005 

GWEI’s in the CPA to evaluate the impact of offshore emissions on offshore and onshore ozone air 

quality, in which they proposed an emission-reduction scenario. They found a particular ozone episode 

that the onshore impact from all offshore oil-and-gas-related sources was small but generally larger than 

those estimates using the year 2000 inventory. They noticed higher simulated ozone concentrations from 

the year 2005 emissions due to increases in NOx and VOC concentrations.

A second follow-up study was conducted in 2008 using the updated year 2005 Gulfwide Emission 

Inventory Study to model ozone formation in Louisiana, Mississippi, Alabama, and Florida based on an 

August 1999 ozone episode (Haney et al., 2008). In this study, OCS oil and gas activity contributed only 

slightly to the simulated onshore ozone exceedances.
Air Quality Offshore Modeling Analysis A-5 

A third follow-up study will conducted by March 2014. This study will use the updated Year 2008 

Gulfwide Emission Inventory Study (Wilson et al., 2010) to model ozone formation, and it will include a 

1-hour inventory.

OCD Model Protocol

The OCD 5 model was used to analyze a CPA proposed action’s impacts on the onshore community. 

BOEM’s regulations at 30 CFR § 550.303 cite that an approved model should be used to assess impacts. 

The USEPA lists approved models in 40 CFR part 51, appendix W 7.2.4., “Modeling Guidance for Other 

Governmental Programs.” The model was used to compute concentrations of sulfur dioxide (SO2), 

nitrogen oxides (NOx), volatile organic carbon compounds (VOC’s), carbon monoxide (CO), and 

particulate matter below 10 micrometers (PM10) and below 2.5 micrometers (PM2.5) in size.

BOEM’s regulations do not include ozone as it is not directly emitted into the air from OCS oil and 

gas activities. BOEM does regulate the pollutants, VOC and NO2, which are precursors to ozone. Ozone 

formation from VOC’s and NO2 is dependent upon a photochemical reaction in the ambient air that 

includes heat and sunlight. Ozone formation is a problem in onshore urban areas with many sources of 

pollutants. The OCD model cannot simulate ozone generation. Several studies that BOEM has 

conducted and that are discussed above have shown that OCS activities are only a small contributor to 

onshore ozone exceedance so there was no need to perform ozone modeling. Estimates of the amount of 

activity that will result from a proposed CPA lease sale was made using the scenarios for an individual 

typical lease sale and all cumulative OCS activities in the CPA (Tables A-1 and A-2). BOEM can 

attribute an amount of emissions generated by each activity through information collected in the Year 

2008 Gulfwide Emission Inventory Study (Wilson et al., 2010) and Rigzone (2009). A spreadsheet was

developed based on the findings of this study (Billings et al., official communication, 2012). Using the 

level of activity and the activity’s known emissions, total emissions were determined for each type of 

activity for each of the 40 years of the analysis period for a CPA proposed action.

Yearly emissions from all of these activities and sources were summed together and modeled: 

exploration and delineation drilling; development and production drilling; platform installation and 

removal; pipeline installation; production platform operations; tanker loading; tanker in transit; tanker 

unloading; and helicopters and support vessels. Drilling comprises approximately 60-75 percent of the 

total emissions. Emissions for the year with the highest annual emissions during the 40-year analysis 

period (tons/year) and the cumulative sum of all emissions from all OCS-related activities in the CPA 

during the 40-year analysis period (tons) are shown in Tables A-2. The data in the EIS spreadsheets were 

based on an average drillship as reported in Wilson et al. (2010) and Rigzone (2009) for the Gulf of 

Mexico. Drilling days and average kilowatts were used to calculate reasonably foreseeable emissions. 

Specific drillships can be significantly larger or smaller than the average value used in the spreadsheet 

and greater total emissions could be generated if the drillship stays on location longer. These averages 

may not, in every situation, directly translate to the short-term (as opposed to annual) NAAQS; 

nevertheless, BOEM’s subject-matter experts believe that the analysis remains conservative with regards 

to reasonably foreseeable emissions expected to result from a CPA proposed action.

The single sale projected emissions were then assigned to a block within the CPA for OCD 5 

modeling. Modeling emissions from cumulative sales was not performed because although the 

cumulative emissions are greater than the lease sale emissions, the emissions would be widely distributed 

across the planning areas and would be the result of activities based on all stages of the life of the lease. 

Since drilling is the activity with the greatest emissions and is most concentrated in a new lease, modeling 

for a single lease sale was considered sufficient. At the time of a CPA lease sale, BOEM can only 

generally predict where or when the activities that generate air pollutants will occur during the 40-year 

analysis period within the planning areas. Of the various types of drilling rigs, the drillship was chosen 

because it generates the greatest amount of emissions since it is not anchored to the seafloor. Instead, the 

drillship depends on engines to stay on location. Thus, the drillship’s emissions result from both drilling 

and the thrusters used to maintain location. A drillship generates 773 tons of NOx per well whereas a 

jack-up rig generates 47 tons of NOx per well. The selected CPA source (Mississippi Canyon Block 856 

[MC 856]) is about 56 miles (90 kilometers) from the closest shoreline and 95 miles (153 kilometers) 

from the Breton Class I area. All of the emissions from the year with the highest activity were placed in 

one location rather than distributed across the proposed CPA lease sale area. The modeling scenarios are 

presented in Table A-3. 
A-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

The meteorological data used are described in BOEM’s Five-Year Meteorological Datasets for 

CALMET/CALPUFF and OCD5 Modeling of the Gulf of Mexico Region (Douglas and Hudischewskyj, 

2008). The meteorological files to use in the OCD 5 model were prepared using onshore surface and 

upper-air data from the National Weather Service, mixing height estimates obtained from the National 

Climatic Data Center, and offshore buoy data from the National Data Buoy Center (Douglas and 

Hudischewskyj, 2008). The meteorological data used were from the period 2000 through 2004. For 

MC 856, surface data come from Patterson, Louisiana, and upper air data come from Slidell, Louisiana. 

Buoy data for MC 856 come from Buoy 42040. These meteorological data points are the closest, 

physically, to the proposed lease sale area available to BOEM and, therefore, are the best approximation 

available.

The modeling domain was selected to include the closest shoreline area potentially impacted by 

emissions. Receptors were set at the Breton Class I area and the shoreline for the CPA. State’s shoreline 

and the Breton Class I area were included. For the MC 856 source, 2 Florida, 3 Alabama, 3 Mississippi, 

17 Louisiana, and 10 Breton Class I receptors were used.

Limitations

There are limitations associated with this modeling effort. The OCD 5 model was selected because it 

was specifically designed to include overwater conditions. The other models, which might have been 

selected, would possibly have included features such as the ability to determine ozone formation and the 

ability to model vessel emissions as a moving rather than stationary source. These models were not 

chosen because they are either not approved in USEPA’s Appendix W or they do not reflect overwater 

conditions.

Furthermore, a more realistic estimation of shoreline impacts could have been obtained by 

distributing the sources of emissions across the OCS rather than using the assumption that all emissions 

occur at a single location in the CPA (MC 856). Results are not available for every point on the coast. 

The inclusion of more receptor locations would provide greater detail to the results. Modeling did not 

include every type of exploration and production activity or accidental event. Modeling did not include 

drilling at a location closer to shore with emissions representative of a more appropriate bottom-founded 

rig. 

Nevertheless, by using a reasonable conservative approach, which includes the overestimation of 

reasonable emissions, and attribution of the source of these emissions to a single point in each of the 

proposed lease sale areas rather than at more dispersed source points throughout the proposed lease sale 

areas, and by using the conservative OCD 5 model, which is specifically designed to represent the 

offshore and coastal environment, the results of this modeling effort adequately represent a demonstration 

of the impacts of offshore emissions to the shoreline and to the Class I area.

OCD Model Results

The major pollutant emitted from a CPA proposed action is NOx, while PM10 is the least emitted 

pollutant. Platform operations are contributors of VOC emissions. Commercial marine vessels are 

contributors of SO2 and PM emissions. Support activities for OCS activities including crew and supply 

boats, helicopters, and pipeline vessels consist mainly of NOx and CO emissions. Combustion-intensive 

operations such as platform operations, well drilling, and service-vessel activities contribute mostly to 

NOx. 

Since NOx has the highest potential emissions for OCS activities, annual NO2 and 1-hour NO2 were 

analyzed and compared with the NAAQS. To be conservative, all emissions of NOx were assumed to be 

equal to NO2 for modeling purposes. Results are provided in Table A-4 for the CPA Class I and Class II

areas. 

CPA

The results for the Class I (Breton National Wilderness) and Class II areas also demonstrate that a 

CPA proposed action’s modeled impacts are below BOEM’s Significance Levels and Maximum 

Allowable Increases, NAAQS, and the U.S. Environmental Protection Agency’s SIL’s for all the criteria 

pollutants except for the annual NOx and the 24-hour PM2.5. Although the SIL’s were exceeded, BOEM 

expects in practice, if the emissions were distributed more realistically across the CPA, that emissions 
Air Quality Offshore Modeling Analysis A-7 

would not exceed the SIL; and thus, actual emissions likely to result from a CPA proposed action would 

likely not be significant. The modeling that was conducted was overly conservative. All the emissions 

during 1 year for the entire CPA, which would actually be dispersed throughout the CPA, were modeled 

as if they originated in Mississippi Canyon Block 856. BOEM is confident that the modeled impacts 

from OCS activity continue to support its conclusion that the proposed action will only minimally impact 

onshore air quality. 

The results also indicate that the maximum modeled concentrations for the 1-hour averaging period 

for the NO2 combined with the nearest representative onshore NO2 monitored concentrations do not 

exceed the NO2 1-hour NAAQS for the Breton National Wilderness Area as well as for the entire CPA 

(Table A-4). Although BOEM’s regulations do not include a 1-hour NO2 standard, BOEM modeled 

1-hour NO2 impacts from a CPA proposed action because the 1-hour standard is harder to meet than 

BOEM’s annual NOx maximum allowable increase. The results of the modeled impacts support the 

conclusion that there will be minimal impacts to onshore air quality.

Conclusion

Based on studies conducted in 1995, 2000, and 2008, BOEM has determined that OCS activities 

contributed only slightly to onshore ozone exceedances in the Houston/Brazoria/Galveston areas of 

Texas, and the States of Louisiana, Mississippi, Alabama, and Florida. Consequently, ozone modeling 

was not performed for this analysis. The OCD model was selected to model for the pollutants CO, NOx, 

SOx, PM2.5, and PM10. BOEM used a conservative approach in choosing and populating the OCD model 

for this analysis, which includes the overestimation of reasonable emissions and the attribution of the 

source of these emissions to a single point in each of the proposed lease sale areas rather than at more 

realistic source points throughout the proposed lease sale areas. The conservative OCD 5 model is 

specifically designed to represent the offshore and coastal environments. The results of this modeling 

effort adequately represent a demonstration of the impacts of offshore emissions to the shoreline and to 

the Class I area.

The OCD 5 modeling was performed for the CPA Class I area and the CPA Class II areas. The CPA 

hypothetical source location was chosen approximately 56 miles (90 kilometers) from shore. Even with 

all the emissions being attributed to a single point, which would not be the case in reality, CPA emissions 

would minimally impact onshore air quality. Significant impacts to air quality are not expected to result 

from a CPA proposed action.

Preparers

Margaret Metcalf, Supervisor, Physical Sciences Unit

Stacie Merritt, Physical Scientist

Chester Huang, Meteorologist

Eric Wolvovsky, Physical Scientist
A-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

References

Billings, R., B. Lange, and D. Wilson. 2012. Official communication. Emission estimates for Eastern 

Planning Area Sales 225-226. Memorandum to Holli Ensz, U.S. Dept. of the Interior, Bureau of 

Ocean Energy Management, Gulf of Mexico OCS Region, New Orleans, LA. Eastern Research 

Group, Inc., September 7, 2012. 9 pp.

Douglas, S.G. and A.B. Hudischewskyj. 2008. Five-year meteorological datasets for 

CALMET/CALPUFF and OCD5 modeling of the Gulf of Mexico Region. U.S. Dept. of the Interior, 

Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 

2008-029. 53 pp.

Haney, J.L., Y. Wei, T. Myers, and S. Douglas. 2008 (unpublished). An assessment of onshore air 

quality impacts for the eastern Gulf Coast (Louisiana to Florida) using the 2005 Gulfwide emissions 

inventory. Prepared for the U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico 

OCS Region, New Orleans, LA.

Rigzone. 2009. Offshore rig search. Internet website: http://www.rigzone.com. Accessed November 7, 

2013.

Systems Applications International, Sonoma Technology, Inc., Earth Tech, Alpine Geophysics, and 

A.T. Kearney. 1995. Gulf of Mexico air quality study: Final report. Volumes I-III. U.S. Dept. of 

the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS 

Study MMS 95-0038, 95-0039, and 95-0040. 650, 214, and 190 pp., respectively.

Turner, D.B. and R.H. Schulze. 2007. Practical guide to atmospheric dispersion modeling. Dallas, TX: 

Trinity Consultants.

Wilson, D.L., R, Billing, R. Oommen, and B. Lange. 2010. Year 2008 Gulfwide emission inventory 

study. U.S. Dept. of the Interior, Bureau of Ocean Energy Management, Regulation and 

Enforcement, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study BOEMRE 2010-045. 

185 pp.

Yarwood, G., G. Mansell, M. Jimenez, and S. Lau. 2004 (unpublished). 2000 Gulf-wide emissions 

inventory – OCS on-shore impacts modeling (Texas), a preliminary look. Prepared for the U.S. Dept. 

of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. 

Prepared by ENVIRON International Corporation, Novato, CA. September 1, 2004. 
Air Quality Offshore Modeling Analysis

A-9

Table A-1

Central Planning Area – Estimate of High-Case Emissions for a Single Sale: Highest Year of Emissions during the 40-Year Period of Activity (tons/year)

NOx SOx PM10 PM2.5 VOC CO CO2 CH4 N2O

Exploration/Delineation Well Drilling 10,568.34 246.01 380.32 368.91 207.04 2,327.83 802,296.17 6.63 24.85

Development/Production Well Drilling 4,561.63 5.02 152.84 148.26 91.83 1,133.34 408,984.93 3.38 12.67

Platform Installation and Removal 216.56 2.73 7.42 7.20 3.17 57.68 17,257.87 0.10 0.79

Pipeline Installation 133.88 1.85 3.79 3.68 3.91 27.73 14,406.80 0.17 0.66

Production Platforms 3,157.65 43.40 33.16 32.69 2,576.37 3,491.76 357,786.08 17,940.43 5.32

Tankers Loading 0.14 0.02 0.0034 0.0031 31.51 0.0136 5.98 6.16E-05 0.0002

Tankers in Transit 5.08 0.60 0.12 0.11 0.58 0.50 221.61 0.0011 0.01

Tankers Unloading 0.14 0.01 0.0034 0.0031 9.68 0.0136 5.98 6.16E-05 0.0002

Helicopters 33.5310 8.2700 6.6166 6.6166 81.6128 408.83 41,353.82 0.00E+00 0.00E+00

Support Vessels 2,038.47 2.49 69.85 67.76 29.84 542.92 162,447.60 0.99 7.42

Total 20,715.42 310.41 654.13 635.23 3,035.54 7,990.61 1,804,766.85 17,951.70 51.71

CH4 – methane

CO – carbon monoxide

CO2 – carbon dioxide

N2O – nitrous oxide

NOx – nitrogen oxides

PM10 – particulate material less than 10μm in size

PM2.5 – particulate material less than 2.5μm in size

SOx – sulfur oxides

VOC – volatile organic compound
A-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table A-2

Central Planning Area – Estimate of High-Case Emissions for Cumulative Sales: Total Emissions during the 40-Year Period of Activity (tons)

NOx SOx PM10 PM2.5 VOC CO CO2 CH4 N2O

Exploration/Delineation Well Drilling 1,418,906.52 3,797.42 47,632.79 46,203.81 28,854.46 347,702.69 126,296,548.05 1,058.08 3,799.01

Development/Production Well Drilling 1,73,8078.63 2,390.40 58,097.52 56,354.60 35,394.37 428,711.63 156,091,192.49 1,307.67 4,694.93

Platform Installation and Removal 59,513.87 126.70 2,053.02 1,991.43 869.36 15,726.68 4,698,377.58 27.67 214.46

Pipeline Installation 60,497.90 177.59 1,728.99 1,677.12 1,770.85 12,456.98 6,432,426.19 75.80 293.74

Production Platforms 2,192,552.79 30,138.08 23,021.72 22,697.05 1,788,929.87 2,424,540.85 248,432,794.68 12,457,138.92 3,694.40

Tankers Loading 7.71 0.11 0.19 0.17 1,774.84 0.76 336.78 0.00 0.01

Tankers in Transit 285.97 4.01 7.02 6.43 32.81 28.31 12,484.17 0.06 0.50

Tankers Unloading 7.71 0.08 1.89E-01 1.73E-01 545.14 0.76 336.78 0.0035 0.0134

Helicopters 22,772.43 5,616.57 4.49E+03 4.49E+03 55,426.98 277,657.75 28,085,285.00 0.0000 0.00

Support Vessels 1,233,296.32 1,059.64 4.23E+04 4.10E+04 18,047.48 328,241.63 98,199,575.43 597.3796 4,482.4038

Total 6,725,919.86 43,310.60 179,321.24 174,442.00 1,931,646.16 3,835,068.04 668,249,357.14 12,460,205.60 17,179.46

CH4 – methane

CO – carbon monoxide

CO2 – carbon dioxide

N2O – nitrous oxide

NOx – nitrogen oxides

PM10 – particulate material less than 10μm in size

PM2.5 – particulate material less than 2.5μm in size

SOx – sulfur oxides

VOC – volatile organic compound
Air Quality Offshore Modeling Analysis

A-11

Table A-3 

Modeling Scenarios

Modeling

Scenarios

Source Location

Activity Represented NOx

(g/sec)

SOx 

(g/sec)

PM10 

(g/sec)

PM2.5 

(g/sec)

VOC

(g/sec)

CO

Area Area/ Block (g/sec)

1 CPA MC 856

All activity during the year 

with the highest lease sale

emissions

595.9 8.9 18.8 18.3 87.3 229.9

CO – carbon monoxide

CPA – Central Planning Area

g/sec – grams per second

MC – Mississippi Canyon

NOx – nitrogen oxides

PM10 – particulate material less than 10μm in size

PM2.5 – particulate material less than 2.5μm in size

SOx – sulfur oxides

VOC – volatile organic compound
A-12 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table A-4 

OCD Modeling Results for a CPA Proposed Action Compared with USEPA’s Significance Impact Levels and the NAAQS

Pollutant Averaging 

Times

BOEM 

Significance 

Levels 

(μg/m3

) 

BOEM

Maximum Allowable 

Increases

(μg/m3)

NAAQS

(μg/m3

) 

USEPA

PSD Significance 

Impact Levels 

(μg/m3)

BOEM

Modeled Impacts

for the CPA

(μg/m3)

Class I Class II Class I Class II Class I Class II

CO 8-hour 500 None None 10,000 None 500 None None

1-hour 2,000 None None 40,000 None 2,000 None None

NO2 Annual 1 None None 100 0.1 1 0.4 0.6

1-hour None None None 188 TBD 7.5a 55.4b 177.67c

SO2 Annual 1 2 20 80d 0.1 1 0.01 0.0

24-hour 5 5 91 365d 0.2 5 0.1 0.2

3-hour 25 2 512 1,300 1 25 0.5 0.5

1-hour None None None 196 TBD 7.86a 0.8 1.3

PM2.5e Annual 1 5 19 12 0.06 0.3 0.0 0.0

24-hour 5 10 37 35 0.07 1.2 0.3 0.4

PM10e Annual 0.2 1 0.0 0.0

24-hour 0.3 5 0.3 0.4

μg/m3 – micrograms per cubic meter

BOEM – Bureau of Ocean Energy Management

CO – carbon monoxide

CPA – Central Planning Area

NAAQS – National Ambient Air Quality Standards

NO2 – nitrogen dioxide

OCD – Offshore and Coastal Dispersion

PM10 – particulate material less than 10μm in size

PM2.5 – particulate material less than 2.5μm in size

SOx – sulfur oxides

TBD – to be determined

USEPA – U.S. Environmental Protection Agency
APPENDIX B 

 

CATASTROPHIC SPILL EVENT ANALYSIS: 

HIGH-VOLUME, EXTENDED-DURATION OIL SPILL

RESULTING FROM LOSS OF WELL CONTROL 

ON THE GULF OF MEXICO OUTER CONTINENTAL SHELF

Catastrophic Spill Event Analysis B-iii

TABLE OF CONTENTS

Page

FIGURES.................................................................................................................................................. B-v

TABLES .................................................................................................................................................. B-vi

B. CATASTROPHIC SPILL EVENT ANALYSIS: HIGH-VOLUME, EXTENDED-DURATION 

OIL SPILL RESULTING FROM LOSS OF WELL CONTROL ON THE GULF OF MEXICO 

OUTER CONTINENTAL SHELF .................................................................................................... B-1

B.1. Introduction............................................................................................................................. B-1

B.1.1. What is a Catastrophic Event?.................................................................................. B-1

B.1.2. Methodology ............................................................................................................ B-2

B.1.2.1. Geographic Scope ................................................................................... B-2

B.1.2.2. Impact-Producing Factors and Scenario ................................................. B-3

B.1.2.3. OSRA Catastrophic Run ......................................................................... B-3

B.1.2.4. Environmental and Socioeconomic Impacts........................................... B-3

B.1.3. How to Use This Analysis........................................................................................ B-3

B.2. Impact-Producing Factors and Scenario (Phases 1-4) ............................................................ B-4

B.2.1. Phase 1—Initial Event.............................................................................................. B-4

B.2.2. Phase 2—Offshore Spill........................................................................................... B-4

B.2.2.1. Duration of Spill...................................................................................... B-4

B.2.2.1.1. Shallow Water...................................................................... B-5

B.2.2.1.2. Deep Water........................................................................... B-5

B.2.2.2. Area of Spill............................................................................................ B-5

B.2.2.3. Volume of Spill....................................................................................... B-5

B.2.2.3.1. Shallow Water...................................................................... B-6

B.2.2.3.2. Deep Water........................................................................... B-6

B.2.2.4. Oil in the Environment: Properties and Persistence............................... B-6

B.2.2.5. Release of Natural Gas............................................................................ B-7

B.2.2.6. Deepwater Subsea Containment ............................................................. B-7

B.2.2.7. Offshore Cleanup Activities.................................................................... B-8

B.2.2.7.1. Shallow Water...................................................................... B-8

B.2.2.7.2. Deep Water........................................................................... B-9

B.2.2.7.3. Vessel Decontamination Stations......................................... B-9

B.2.2.8. Severe Weather ..................................................................................... B-10

B.2.3. Phase 3—Onshore Contact..................................................................................... B-11

B.2.3.1. Duration ................................................................................................ B-11

B.2.3.1.1. Shallow Water.................................................................... B-11

B.2.3.1.2. Deep Water......................................................................... B-11

B.2.3.2. Volume of Oil Contacting Shore........................................................... B-11

B.2.3.3. Length of Shoreline Contacted.............................................................. B-12

B.2.3.3.1. Shallow Water.................................................................... B-12

B.2.3.3.2. Deep Water......................................................................... B-12

B.2.3.4. Severe Weather ..................................................................................... B-12

B.2.3.5. Onshore Cleanup Activities .................................................................. B-13

B.2.3.5.1. Shallow Water.................................................................... B-13

B.2.3.5.2. Deep Water......................................................................... B-13
B-iv Central Planning Area Lease Sales 235, 241, and 247 EIS

B.2.3.5.3. Response Considerations for Sand Beaches for Both 

Shallow-Water and Deepwater Spills................................. B-13

B.2.3.5.4. Response Considerations for Marshes for Both ShallowWater and Deepwater Spills............................................... B-14

B.2.3.5.5. Response Considerations for Nearshore Waters for Both 

Shallow-Water and Deepwater Spills................................. B-14

B.2.4. Phase 4—Post-Spill, Long-Term Recovery ........................................................... B-14

B.2.4.1. Response Considerations for Sand Beaches, Marshes, and Nearshore 

Waters for both Shallow-Water and Deepwater Spills ......................... B-15

B.3. Description of the Environment and Impact Analysis.......................................................... B-15

B.3.1. Long Duration—Large Volume Spill within the Gulf of Mexico.......................... B-15

B.3.1.1. Air Quality ............................................................................................ B-15

B.3.1.2. Water Quality........................................................................................ B-18

B.3.1.3. Coastal Barrier Beaches and Associated Dunes.................................... B-22

B.3.1.4. Wetlands................................................................................................ B-24

B.3.1.5. Seagrass Communities.......................................................................... B-26

B.3.1.6. Live Bottoms (Pinnacle Trend and Low Relief) ................................... B-28

B.3.1.7. Topographic Features............................................................................ B-34

B.3.1.8. Sargassum Communities....................................................................... B-40

B.3.1.9. Chemosynthetic Deepwater Benthic Communities............................... B-43

B.3.1.10. Nonchemosynthetic Deepwater Benthic Communities......................... B-46

B.3.1.11. Soft Bottom Benthic Communities....................................................... B-51

B.3.1.12. Marine Mammals.................................................................................. B-56

B.3.1.13. Sea Turtles............................................................................................. B-59

B.3.1.14. Diamondback Terrapins........................................................................ B-63

B.3.1.15. Beach Mice ........................................................................................... B-65

B.3.1.16. Coastal, Marine, and Migratory Birds................................................... B-66

B.3.1.17. Fish Resources and Essential Fish Habitat............................................ B-72

B.3.1.18. Commercial Fisheries............................................................................ B-75

B.3.1.19. Recreational Fishing.............................................................................. B-77

B.3.1.20. Recreational Resources......................................................................... B-78

B.3.1.21. Archaeological Resources..................................................................... B-80

B.3.1.22. Land Use and Coastal Infrastructure..................................................... B-83

B.3.1.23. Demographics ....................................................................................... B-84

B.3.1.24. Economic Factors.................................................................................. B-85

B.3.1.25. Environmental Justice ........................................................................... B-86

B.3.1.26. Species Considered due to U.S. Fish and Wildlife Service Concerns .. B-90

B.4. Preparers ............................................................................................................................... B-92

B.5. References............................................................................................................................. B-92
Catastrophic Spill Event Analysis B-v 

FIGURES

Page

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

Study Area. ..................................................................................................................... B-117

Figure B-2. Spatial Frequency (%) of the Watermass Associated with the Loop Current in the 

Eastern Gulf of Mexico based on Data for the Period 1976-2003. ................................. B-118

Figure B-3. Summary of Avian Species Collected by Date Obtained from the U.S. Fish and Wildlife 

Service as Part of the Deepwater Horizon Post-Spill Monitoring and Collection Process 

through May 12, 2011..................................................................................................... B-119
B-vi Central Planning Area Lease Sales 235, 241, and 247 EIS

TABLES

Page

Table B-1. Blowout Scenarios and Key Differences in Impacts, Response, and/or Intervention..... B-120

Table B-2. Properties and Persistence by Oil Component Group..................................................... B-121

Table B-3. Annual Volume of Produced Water Discharged by Depth (millions of barrels)............ B-122

Table B-4. Description of the Scenario for a Catastrophic Spill Event Occurring in 

Shallow Water or Deep Water ........................................................................................ B-123

Table B-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: PostDeepwater Horizon Explosion, Oil Spill, and Response in the Gulf of Mexico ............ B-126

Table B-6. Federally Listed Avian Species Considered by State and Associated Planning Area 

in the Gulf of Mexico1 .................................................................................................... B-133
Catastrophic Spill Event Analysis B-1 

B. CATASTROPHIC SPILL EVENT ANALYSIS: HIGH-VOLUME, 

EXTENDED-DURATION OIL SPILL RESULTING FROM LOSS 

OF WELL CONTROL ON THE GULF OF MEXICO OUTER 

CONTINENTAL SHELF

B.1. INTRODUCTION

In 1986, the Council on Environmental Quality (CEQ) regulations were amended to rescind the 

requirement to prepare a “worst-case analysis” for an environmental impact statement (EIS) (refer to 

40 CFR § 1502.22(b)(4)). The regulation, as amended, states that catastrophic, low-probability impacts 

must be analyzed if the analysis is “supported by credible scientific evidence, is not based on pure 

conjecture, and is within the rule of reason.”

The August 16, 2010, CEQ report, prepared following the Deepwater Horizon explosion, oil spill, 

and response in the Gulf of Mexico, recommended that the Bureau of Ocean Energy Management 

(BOEM), formerly the Minerals Management Service (MMS) and Bureau of Ocean Energy Management, 

Regulation and Enforcement (BOEMRE), should “ensure that National Environmental Policy Act

(NEPA) documents provide decisionmakers with a robust analysis of reasonably foreseeable impacts, 

including an analysis of reasonably foreseeable impacts associated with low-probability catastrophic 

spills for oil and gas activities on the Outer Continental Shelf” (CEQ, 2010). This evaluation is a robust 

analysis of the impacts from low-probability catastrophic spills and will be made available to all 

applicable decisionmakers including, but not limited to, the Secretary of the Department of the Interior 

(USDOI) for the National Five-Year Program, the Assistant Secretary of Land and Minerals Management 

for an oil and gas lease sale, and the Regional Supervisors of the Gulf of Mexico OCS Region’s Office of 

Environment and Office of Leasing and Plans.

It should be noted that the analysis presented here is intended to be a general overview of the 

potential effects of a catastrophic spill in the Gulf of Mexico. As such, the Catastrophic Spill Event 

Analysis should be read with the understanding that further detail about accidental oil impacts on a 

particular resource may be found in the Gulf of Mexico OCS Oil and Gas Lease Sales: 2015-2017 

Central Planning Area Lease Sales 235, 241, and 247, Draft Supplemental Environmental Impact 

Statement (CPA 235, 241, and 247 Supplemental EIS) analysis or previous relevant NEPA analyses (e.g., 

the Gulf of Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western Planning Area Lease Sales 229, 

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

Environmental Impact Statement [2012-2017 WPA/CPA Multisale EIS]; USDOI, BOEM, 2012; the Gulf 

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

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

Supplemental EIS]; USDOI, BOEM, 2013a; and the Gulf of Mexico OCS Oil and Gas Lease Sales: 2014 

and 2016, Eastern Planning Area Lease Sales 225 and 226, Final Environmental Impact Statement

[EPA 225/226 EIS]; USDOI, BOEM, 2013b). 

B.1.1. What is a Catastrophic Event?

As applicable to NEPA, Eccleston (2008) defines a catastrophic event as “large-scale damage 

involving destruction of species, ecosystems, infrastructure, or property with long-term effects, and/or 

major loss of human life.” For oil and gas activities on the Outer Continental Shelf (OCS), a catastrophic 

event is a high-volume, extended-duration oil spill regardless of the cause, whether natural disaster (i.e., 

hurricane) or manmade (i.e., human error and terrorism). This high-volume, extended-duration oil spill, 

or catastrophic spill, has been further defined by the National Oil and Hazardous Substances Pollution 

Contingency Plan as a “spill of national significance” or “a spill which, because of its severity, size, 

location, actual or potential impact on the public health and welfare or the environment, or the necessary 

response effort, is so complex that it requires extraordinary coordination of federal, state, local, and 

responsible party resources to contain and cleanup the discharge” (40 CFR part 300, Appendix E).

Each oil-spill event is unique; its outcome depends on several factors, including time of year and 

location of release relative to winds, currents, land, and sensitive resources; specifics of the well (i.e., 

flow rates, hydrocarbon characteristics, and infrastructure damage); and response effort (i.e., speed and 
B-2 Central Planning Area Lease Sales 235, 241, and 247 EIS

effectiveness). For this reason, the severity of impacts from an oil spill cannot be predicted based on 

volume alone, although a minimum volume of oil must be spilled to reach catastrophic impacts.

Though large spills may result from a pipeline rupture, such events will not result in a catastrophic 

spill because the ability to detect leaks and shut off pipelines limits the amount of the spill to the contents 

of the pipeline. The largest, non-blowout-related spill on the Gulf of Mexico OCS occurred in 1967, a 

result of internal pipeline corrosion following initial damage by an anchor. In 13 days, 160,638 barrels 

(bbl) of oil leaked (USDOI, BSEE, 2012); however, no significant environmental impacts were recorded 

as a result of this spill.

Although loss of well control is defined as the uncontrolled flow of reservoir fluid that may result in 

the release of gas, condensate, oil, drilling fluids, sand, or water, it is a broad term that includes very 

minor well control incidents as well as the most severe well control incidents. Historically, loss of well 

control incidents occurred during development drilling operations, but loss of well control incidents can 

occur during exploratory drilling, production, well completions, or workover operations. These losses of 

well control incidents may occur between formations penetrated in the wellbore or at the seafloor.

Prior to the Deepwater Horizon explosion, oil spill, and response, the two largest spills resulting from 

a loss of well control in U.S. waters of the Gulf of Mexico occurred in 1970 and released 30,000 and 

53,000 bbl of oil, respectively (USDOI, BSEE, 2012). These incidents resulted in four human fatalities. 

Although these incidents occurred only 8-14 miles (mi) (13-26 kilometers [km]) from shore, there was 

minor shoreline contact with oil (USDOC, NOAA, Office of Response and Restoration, 2010a and 

2010b). In 1987, a blowout of the Mexican exploratory oil well, YUM II, resulted in a spill of 58,640 bbl 

and 75 mi (121 km) of impacted shoreline (USDOC, NOAA, Hazardous Materials Response and 

Assessment Division, 1992). However, none of these spills met the previously described definitions of a 

catastrophic event or spill.

A blowout is a more severe loss of well control incident that creates a greater risk of a large oil spill

and serious human injury. Two blowouts that resulted in catastrophic spills have occurred in U.S. and 

Mexican waters of the Gulf of Mexico. On June 3, 1979, the Ixtoc I well blowout in shallow water (water 

depth of 164 feet [ft] [50 meters [m]] and 50 mi [80 km] offshore in the Bay of Campeche, Mexico) 

spilled 3.5 million barrels (MMbbl) of oil in 10 months (USDOC, NOAA, Office of Response and 

Restoration, 2010c; USDOC, NOAA, Hazardous Materials Response and Assessment Division, 1992; 

ERCO, 1982). On April 20, 2010, the Macondo well blowout (Deepwater Horizon explosion, oil spill, 

and response) in deep water (4,992 ft; 1,522 m) 48 mi (77 km) offshore in Mississippi Canyon Block 252, 

spilled an estimated 4.9 MMbbl of oil until it was capped approximately 3 months later. Due to being 

classified as catastrophic, the Ixtoc I and Macondo well blowouts and spills were utilized to develop the 

catastrophic spill event scenario in this analysis. 

B.1.2. Methodology

Two general approaches are utilized to analyze a catastrophic event under NEPA. The first approach 

is a bounding analysis for each individual resource category (e.g., marine mammals and sea turtles). A 

bounding analysis involves selecting and evaluating a different set of factors and scenarios for each 

resource in the context of a worst-case analysis. The second approach involves the selection of a single 

set of key circumstances that, when combined, result in catastrophic consequences. The second approach 

is used for a site-specific analysis and, consequently, its possible application is more limited. 

Accordingly, this analysis combines the two approaches, relying on a generalized scenario while 

identifying site-specific severity factors for individual resources. This combined approach allows for the 

scientific investigation of a range of possible, although not necessarily probable, consequences of a 

catastrophic blowout and oil spill in the Gulf of Mexico.

B.1.2.1. Geographic Scope

The Gulf of Mexico is a semi-enclosed basin with an extensive history of oil and gas activities and 

unique environmental conditions and hydrocarbon reservoir properties; consequently, this analysis is only 

applicable to the Gulf of Mexico OCS and is not intended for other OCS regions.
Catastrophic Spill Event Analysis B-3 

B.1.2.2. Impact-Producing Factors and Scenario

A hypothetical, yet feasible, scenario (Chapter B.2) was developed to provide a framework for 

identifying the impacts of an extended oil spill from an uncontrolled blowout. Unless noted, this scenario 

is based on the large magnitude, blowout-related oil spills that have occurred in the Gulf of Mexico, i.e., 

Ixtoc I and Macondo well blowouts and spills (discussed in Chapter B.1.1). As noted above, because 

each spill event is unique, its outcome depends on many factors. Therefore, the specific impacts from 

future spills cannot be predicted based on this scenario.

B.1.2.3. OSRA Catastrophic Run

A special Oil-Spill Risk Analysis (OSRA) model run was conducted to estimate the impacts of a 

possible future catastrophic or high-volume, extended-duration oil spill. This analysis emphasized 

modeling a spill that continued for 90 consecutive days by launching spills on each of 90 consecutive 

days, with each trajectory tracked for up to 60 days. The OSRA was conducted for only the trajectories 

of oil spills from hypothetical spill locations to various onshore and offshore environmental resources. 

Though this Appendix is associated with all three planning areas, data from three hypothetical spill 

locations located in the Central Planning Area (CPA) (Figure B-1) were included and are intended for use 

as examples of this type of exercise. Information on previous catastrophic OSRA runs for the CPA can 

be found in Appendix C of this Supplemental EIS and in Appendix C of the 2012-2017 WPA/CPA 

Multisale EIS.

The probability of an oil spill contacting a specific resource within a given time of travel from a spill 

point is termed a conditional probability; the condition being that a spill is assumed to have occurred. 

Each trajectory was allowed to continue for as long as 60 days. However, if the hypothetical spill 

contacted shoreline sooner than 30 days after the start of the spill, the spill trajectory was terminated, and 

the contact was recorded. Although, overall OSRA is designed for use as a risk-based assessment, for this 

analysis, only the conditional probability, the probability of contact to the resource, was calculated. The 

probability of a catastrophic spill occurring was not calculated; thus, the combination of the probability of 

a spill and the probability of contact to the resources from the hypothetical spill locations were not 

calculated. Results from this trajectory analysis provide input to the final product by estimating where 

spills might travel on the ocean’s surface and what environmental resources might be contacted if and 

when another catastrophic spill occurs, but it does not provide input on the probability of another 

catastrophic spill occurring. Further detail on this catastrophic OSRA run is contained in Appendix C. 

B.1.2.4. Environmental and Socioeconomic Impacts

This analysis evaluates the impacts to the Gulf of Mexico’s biological, physical, and socioeconomic 

resources from a catastrophic blowout, oil spill, and associated cleanup activities.

Although the most recent EIS’s prepared by this Agency for oil and gas lease sales in the Gulf of 

Mexico analyze the potential impacts from smaller oil spills that are more reasonably foreseeable 

(USDOI, MMS, 2007 and 2008), this analysis focuses on the most likely and most significant impacts 

created by a high-volume, extended-duration spill. Because catastrophic consequences may not occur for 

all resources, factors affecting the severity of impacts are identified by the individual resource.

B.1.3. How to Use This Analysis

The purpose of this technical analysis is to assist BOEM in meeting CEQ requirements that require a 

discussion of impacts from catastrophic events. This analysis, based on credible scientific evidence, 

identifies the most likely and most significant impacts from a high-volume blowout and oil spill that 

continues for an extended period of time. The scenario and impacts discussed in Chapters B.2 and B.3

should not be confused with the scenario and impacts anticipated to result from routine activities or the 

more reasonably foreseeable accidental events of a CPA proposed action.

Chapter B.2 is intended to clearly describe the scenario presented for all four phases of a catastrophic 

blowout event and identify the impact-producing factors associated with each phase. Chapter B.3 is 

intended to analyze the impacts of each phase of a catastrophic blowout on various environmental 

resources. These chapters can be used to differentiate the conditions of a catastrophic spill from the 

routine activities and accidental events described in this Supplemental EIS. 
B-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

This technical analysis is designed to be incorporated by reference in future NEPA documents and 

consultations. Therefore, factors that affect the severity of impacts of a high-volume, extended-duration 

spill on individual resources are highlighted for use in subsequent site-specific analyses.

To analyze a hypothetical catastrophic event in an area such as the Gulf of Mexico, several 

assumptions and generalizations were made. However, future project-specific analyses should also 

consider specific details such as potential flow rates for the specific proposed activity, the properties of 

the targeted reservoir, and the proximity to environmental resources of the proposed activities.

B.2. IMPACT-PRODUCING FACTORS AND SCENARIO (PHASES 1-4)

For the purposes of this analysis, an event similar to the Ixtoc I well blowout and spill that occurred in 

1979 in 160-ft (50-m) water depth will be used as the basis for a shallow water spill and an event similar 

to the Macondo well blowout and spill that occurred in 2010 in the Mississippi Canyon area in 5,000-ft 

(1,524-m) water depth will be used to represent a deepwater spill.

B.2.1. Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout incident. While most of the 

environmental and socioeconomic impacts of a catastrophic blowout would occur during the ensuing 

high-volume, extended-duration spill (refer to Chapter B.3), it is important to acknowledge the deadly 

events that could occur in the initial phase of a catastrophic blowout. The following scenario was 

developed to provide a framework for identifying the most likely and most significant impacts during the 

initial phase.

Impacts, response, and intervention depend on the spatial location of the blowout and release. While 

there are several points where a blowout could occur, four major distinctions that are important to the 

analysis of impacts are described in Table B-1. 

For this analysis, an explosion and subsequent fire are assumed to occur. If a blowout associated with 

the drilling of a single exploratory well occurs, a fire could result that would burn for 1 or 2 days. If a 

blowout occurs on a production platform, other wells could feed the fire, allowing it to burn for over a 

month (USDOC, NOAA, Office of Response and Restoration, 2010b). The drilling rig or platform may 

sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. For example, when the drilling rig Deepwater Horizon sank, it landed 1,500 ft (457 m) 

away on the seafloor. Regardless of water depth, the immediate response would be from search and 

rescue vessels and aircraft, such as United States Coast Guard (USCG) cutters, helicopters, and rescue 

planes.

B.2.2. Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters.

B.2.2.1. Duration of Spill

The duration of the offshore spill from a blowout depends on the time needed for intervention and the 

time the remaining oil persists offshore. If a blowout occurs and the damaged surface facilities preclude 

well reentry operations, a relief well may be needed to regain control. The time required to drill the relief 

well depends on the complexity of the intervention, the location of a suitable rig, the type of operation 

that must be terminated to release the rig (e.g., casing may need to be run before releasing the rig), and the 

logistics in mobilizing personnel and equipment to the location. A blown-out well may also be 

successfully capped prior to completion of relief wells, as occurred in the Macondo well blowout. In 

terms of persistence of spilled oil on surface waters, oil from the Macondo well blowout did not persist 

for more than 30 days (OSAT, 2010). However, based on BOEM’s weathering modeling (refer to 

Appendix C), it is assumed that oil could persist on surface waters for as long as 1-2 months, depending 

on the season and year.
Catastrophic Spill Event Analysis B-5 

B.2.2.1.1. Shallow Water

If a blowout occurs in shallow water, it is estimated that the entire well intervention effort including 

drilling relief wells, if deemed necessary, could take 1-3 months. This estimate would include 1-3 weeks 

to transport the drilling rig to the well site. Spilled surface oil is not expected to persist more than 

1-2 months (depending upon the season and environmental conditions) after the flow is stopped. Spilled 

oil is more likely to persist in the offshore environment during colder weather and during wind and 

hydrodynamic conditions that keep the oil offshore. Therefore, the estimated spill duration resulting from 

a shallow water blowout is 2-5 months (approximately 1-3 months for active spillage and 1-2 months for 

oil persistence in the environment).

B.2.2.1.2. Deep Water

If a blowout occurs in deep water, it is estimated that it would take 2-4 weeks to remove debris and to 

install a capping stack or a cap and flow system on a well, if conditions allow this type of intervention. 

The entire intervention effort including drilling relief wells, if deemed necessary, could take 3-4 months 

(USDOI, MMS, 2000; Regg, 2000). This includes 2-4 weeks to transport the drilling rig to the well site. 

Spilled surface oil is not expected to persist more than 1-2 months (depending upon the season and 

environmental conditions) after the flow is stopped. Spilled oil is more likely to persist in the offshore 

environment during colder weather and during wind and hydrodynamic conditions that keep the oil 

offshore. Therefore, the estimated spill duration from a deepwater blowout is 2-6 months (approximately 

1-4 months for active spillage and 1-2 months for oil persistence in the environment).

B.2.2.2. Area of Spill

When oil reaches the sea surface, it spreads. The speed and extent of spreading depends on the type 

and volume of oil that is spilled. However, a catastrophic spill would likely spread to hundreds of square 

miles. Also, the oil slick may break into several smaller slicks, depending on local wind patterns that 

drive the surface currents in the spill area.

Subsurface oil observed during both the Ixtoc I and Macondo well blowouts and spills could also 

spread to significant distances depending on environmental conditions (such as hydrodynamics), oil 

chemistry and weathering, and the application of subsea dispersants or mechanical conditions at the 

release point that would diffuse the oil.

B.2.2.3. Volume of Spill

After 50 years of oil and gas exploration and development activity on the continental shelf of the Gulf 

of Mexico in the CPA and WPA, most of the largest oil and natural gas reservoirs thought to exist in 

shallow water areas of the GOM at drill depths less than 15,000 ft (4,572 m) subsea have been identified. 

Large undiscovered hydrocarbon reservoirs are still thought to exist in the shallow water areas of the CPA 

and WPA. However, results taken from BOEM’s most recent resource assessment study and a review of 

the more recent shallow-water drilling and leasing activity suggest that future discoveries of large 

reservoirs in the shallow-water areas of the GOM are likely to exist greater than 15,000 ft (4,572 m) 

below sea level where geologic conditions are more favorable for natural gas reservoirs to exist than oil 

reservoirs. In contrast to the shallow-water areas of the GOM where the discovery of a new, large, 

prolific oil reservoir is considered a low-probability event, the results from BOEM’s resource assessment 

study pertaining to the deeper water areas of the GOM suggest that there is a high probability that many 

large oil and gas reservoirs have yet to be discovered in deep water. BOEM’s forecast for deep water has 

support from other public and private sector resource studies. The forecast is also supported by the results 

of BOEM’s analysis of deepwater leasing and drilling activity, which indicates that the industry is leasing 

acreage in deepwater areas of the GOM where large prospects can be identified and where the majority of 

exploration and development drilling activity targets potentially thick oil reservoirs capable of achieving 

the high production rates necessary to offset the high costs associated with deep water oil development in 

the GOM.
B-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

B.2.2.3.1. Shallow Water

For this analysis, an uncontrolled flow rate of 30,000 bbl per day is assumed for a catastrophic 

blowout in shallow water. This assumption is based upon the results of well tests in shallow water and 

the maximum flow rate from the 1979 Ixtoc I well blowout, which occurred in shallow water. Using this 

flow rate, the total volume of oil spilled from a catastrophic blowout in shallow water is estimated at 

900,000 bbl to 3 MMbbl from spillage occurring over 1-3 months. In addition to the flow rate, it is 

assumed that any remaining diesel fuel from a sunken drilling rig or platform would also leak.

B.2.2.3.2. Deep Water

For the purposes of this analysis, an uncontrolled flow rate of 30,000-60,000 bbl per day is assumed 

for a catastrophic blowout in deep water. This flow rate is based on the assumption in Chapter B.2.2.3.1

above, well test results, and the maximum flow rate estimated for the Macondo well blowout and spill, 

which occurred in deep water. Therefore, the total volume of oil spilled is estimated to be 0.9-7.2 MMbbl 

over 1-4 months. In addition, deepwater drilling rigs or platforms hold a large amount of diesel fuel 

(10,000-20,000 bbl). Therefore, it is assumed that any remaining diesel fuel from a sunken structure 

would also leak and add to the spill.

B.2.2.4. Oil in the Environment: Properties and Persistence

The fate of oil in the environment depends on many factors, such as the source and composition of the 

oil, as well as its persistence (NRC, 2003). Persistence can be defined and measured in different ways 

(Davis et al., 2004), but the National Research Council (NRC) generally defines persistence as how long 

oil remains in the environment (NRC, 2003; page 89). Once oil enters the environment, it begins to 

change through physical, chemical, and biological weathering processes (NRC, 2003). These processes 

may interact and affect the properties and persistence of the oil through the following:

• evaporation (volatilization);

• emulsification (the formation of a mousse);

• dissolution;

• oxidation (including respiration); and

• transport processes (NRC, 2003; Scholz et al., 1999).

Horizontal transport takes place via spreading, advection, dispersion, and entrainment while vertical 

transport takes place via dispersion, entrainment, Langmuir circulation, sinking, overwashing, 

partitioning, and sedimentation (NRC, 2003). The persistence of an oil slick is influenced by the 

effectiveness of oil-spill response efforts and affects the resources needed for oil recovery (Davis et al., 

2004). The persistence of an oil slick may also affect the severity of environmental impacts as a result of 

the spilled oil.

Crude oils are not a single chemical, but instead are complex mixtures with varied compositions. 

Thus, the behavior of the oil and the risk the oil poses to natural resources depends on the composition of 

the specific oil encountered (Michel, 1992). Generally, oils can be divided into three groups of 

compounds: (1) light-weight; (2) medium-weight; and (3) heavy-weight components. On average, these 

groups are characterized as outlined in Table B-2. 

Of the oil reservoirs sampled in the Gulf of Mexico OCS, the majority fall within the light-weight 

category, while less than one quarter are considered medium-weight and a small portion are considered 

heavy-weight. Oil with an API gravity of 10.0 or less would sink and has not been encountered in the 

Gulf of Mexico OCS; therefore, it is not analyzed in this Appendix (USDOI, BOEMRE, 2010a).

Heavy-weight oil may persist in the environment longer than the other two types of oil, but the 

medium-weight components within oil present the greatest risks to organisms because, with the exception 

of the alkanes, these medium-weight components are persistent, bioavailable, and toxic (Michel, 1992).

Previous studies (e.g., Johansen et al., 2001) supported the theory that most, if not all, released oil 

would reach the surface of the water column. However, data and observations from the Macondo well 
Catastrophic Spill Event Analysis B-7 

blowout and spill challenge that theory. While analyses are in their preliminary stages, it appears that 

measurable amounts of hydrocarbons (dispersed or otherwise) were detected in the water column as 

subsurface “plumes” and on the seafloor in the vicinity of the release. While not all of these 

hydrocarbons have been definitively traced back to releases from the Macondo well, these early 

measurements and results warrant a reassessment of previous theories of the ultimate fate of hydrocarbons 

from unintended subsurface releases. It is important to note that the North Sea experiment (Johansen 

et al., 2001) did not include the use of dispersants at or near the source of the subsea oil discharge.

B.2.2.5. Release of Natural Gas

The quality and quantity of components in natural gas vary widely by the field, reservoir, or location 

from which the natural gas is produced. Although there is not a “typical” makeup of natural gas, it is 

primarily composed of methane (NaturalGas.org, 2012). Thus, if natural gas were to leak into the 

environment, methane may be released into the environment. Limited research is available for the 

biogeochemistry of hydrocarbon gases in the marine environment (Patin, 1999, page 233). Theoretically, 

methane could stay in the marine environment for long periods of time (Patin, 1999, page 237) as 

methane is highly soluble in seawater at the high pressures and cold temperatures found in deepwater

environments (NRC, 2003, page 108). Methane diffusing through the water column would likely be 

oxidized in the aerobic zone and would rarely reach the air-water interface (Mechalas, 1974, page 23). 

Methane is a carbon source and its introduction into the marine environment could result in diminished 

dissolved oxygen concentrations due to microbial degradation.

The Macondo well blowout and spill resulted in the emission of an estimated 9.14 x 109 to 1.29 x 1010

moles of methane from the wellhead (Kessler et al., 2011; Valentine et al., 2010) with maximum 

subsurface methane concentrations of 183-315 micromoles measured in May/June 2010 (Valentine et al., 

2010; Joye et al., 2011). This methane release corresponded to a measurable decrease in oxygen in the 

subsurface plume due to respiration by a community of methanotrophic bacteria. During the Macondo

well blowout and spill, methane and oxygen distributions were measured at 207 stations throughout the 

affected region (Kessler et al., 2011). Based on these measurements, it was concluded that within 

~120 days from the onset of release ~3.0 x 1010 to 3.9 x 1010 moles of oxygen were respired, primarily by 

methanotrophs, and left behind a residual microbial community containing methanotrophic bacteria. The 

researchers further suggested that a vigorous deepwater bacterial bloom respired nearly all the released 

methane within this time and that by analogy, large-scale releases of methane from hydrates in the deep 

ocean are likely to be met by a similarly rapid methanotrophic response. However, hypoxic conditions 

were never reached (OSAT, 2010). Hypoxic conditions are generally agreed to occur when dissolved 

oxygen falls below 2 milligrams/liter (1.4 milliliter/liter) (OSAT, 2010). Note that methane released from 

the Macondo well blowout and spill was generally confined to the subsurface, with minimal amounts 

reaching the atmosphere (Kessler et al., 2011; Ryerson et al., 2011).

B.2.2.6. Deepwater Subsea Containment

To address the new improved containment systems’ expectations to rapidly contain a spill as a result 

of a loss of well control from a subsea well as addressed in Notice to Lessees and Operators (NTL) 

2010-N10, the Marine Well Containment Company (MWCC) and Helix Well Containment Group 

(HWCG) initiated the development of new, rapid response systems. These systems are designed to fully 

contain oil flow in the event of a potential future underwater blowout and to address a variety of 

scenarios. The systems consist of specially designed equipment constructed, tested, and available for 

rapid response. Both the MWCC and the HWCG systems are anticipated to be fully operational within 

days to weeks after a spill event occurs. The availability of these systems can significantly reduce the 

length of time a blowout continues, thereby reducing the amount of oil potentially spilled during a 

catastrophic spill. However, this assumes that a particular blowout situation lends itself to the use of this 

subsea containment technology, whereas there are some situations that may delay or make its use 

improbable, such as the location of debris resulting from the blowout and the condition of the well.

The MWCC system is designed to operate in up to a 10,000-ft (3,048-m) water depth and adds 

containment capability of 60,000 bbl of oil per day. The HWCG system focuses on the utilization of the 

Helix Producer I and the Q4000 vessels. Each of these vessels played a role in the Macondo well 

blowout and spill response, and each of these vessels are continually working in the Gulf. The HWCG 
B-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

system has the ability to fully operate in up to 10,000 ft (3,048 m) of water and has intervention 

equipment to cap and contain a well with the mechanical integrity to be shut-in. The HWCG system also 

has the ability to capture and process 55,000 bbl of oil per day (Helix Well Containment Group, 2010).

In addition, industry has a multitude of vendors available within the GOM region that can provide the 

services and supplies necessary for debris removal capability, dispersant injection capability, and top-hat 

deployment capability. Many of these vendors are already cited for use by MWCC and HWCG.

The BSEE has indicated to BOEM that, it will not allow an operator to begin drilling operations until 

adequate subsea containment and collection equipment, as well as subsea dispersant capability is 

determined by BSEE to be available to the operator and is sufficient for use in response to a potential 

incident from the proposed well(s) (refer to NTL 2010-N10). The BSEE conducted a successful 

deployment drill of Helix’s subsea containment capping stack in July 2012. A deployment drill of 

Helix’s subsea containment capability is presently being planned by BSEE.

B.2.2.7. Offshore Cleanup Activities

As demonstrated by the Ixtoc I and Macondo well blowouts and spills, a large-scale response effort is 

certain to follow a catastrophic blowout. The number of vessels and responders would steadily increase 

as the spill continued. In the event of a spill, particularly a loss of well control, there is no single method 

of containment and removal that would be 100 percent effective. Removal and containment efforts to 

respond to an ongoing spill offshore would likely require multiple technologies, including source 

containment, mechanical cleanup, in-situ burning of the slick, and chemical dispersants. Even with the 

deployment of all of these spill-response technologies, it is likely that, with the operating limitations of 

today’s spill-response technology, not all of the oil could be contained and removed offshore.

B.2.2.7.1. Shallow Water

The following are estimates for the deployment of equipment and personnel during a shallow-water 

spill response. Within the first week of an oil spill originating in shallow water, 25 vessels are estimated 

to respond, which would steadily increase to over 3,000 by the end of the spill. This includes about 

25 skimmers in the vicinity of the well at any given time. In addition, recovered oil may be barged to 

shore from recovery vessels. Within the first week, over 500 responders are estimated to be deployed to a 

spill originating in shallow water, which would steadily increase up to 25,000 before the well is capped or 

killed within 2-4 months. Up to 25 planes and 50 helicopters are estimated to respond per day by the end 

of a shallow-water spill. Response to an oil spill in shallow water is expected to involve over 10,000 ft 

(3,048 m) of boom within the first week and would steadily increase up to 5 million feet (~950 mi; 

~1,520 km) for use offshore and nearshore; the amount is dependent upon the location of the potentially 

impacted shoreline, environmental considerations, and agreed upon protection strategies involving the 

local potentially impacted communities.

Dispersant use must be in accordance with the Regional Response Team’s (RRT) Preapproved 

Dispersant Use Manual and with any conditions outlined within an RRT’s site-specific, dispersant

approval given after a spill event. Consequently, dispersant use would be in accordance with the 

restrictions for specific water depths, distances from shore, and monitoring requirements. At this time, 

this manual does not give preapproval for the application of dispersant use subsea. Aerial dispersants 

would likely be applied from airplanes as a mist, which settles on the oil on the water’s surface. Along 

the Gulf Coast, surface dispersants are presently preapproved for use greater than 3 nautical miles (nmi) 

(3.5 mi; 5.6 km) from shore and in water depths greater than 33 ft (10 m), with the exception of Florida 

(U.S. Dept. of Homeland Security, CG, 2010). At this time, pursuant to a letter from the Florida 

Department of Environmental Protection dated May 5, 2011, sent to USCG, preapproval for dispersant 

use is not approved for any Florida State waters. However, USEPA is presently revisiting these RRT 

preapprovals in light of the dispersant issues, such as subsea application that arose during the Macondo

well blowout and spill response. In addition, revisions are presently being made to the RRT IV and VI’s 

Preapproved Dispersant Use Manuals. The USEPA issued a letter dated December 2, 2010, that provided 

interim guidance on the use of dispersants for major spills that are continuous and uncontrollable for 

periods greater than 7 days and for expedited approval of subsurface applications. This letter outlined the 

following exceptions to the current preapprovals until they are updated:
Catastrophic Spill Event Analysis B-9 

• dispersants may not be applied to major spills that are continuous in nature and 

uncontrollable for a period greater than 7 days;

• additional dispersant monitoring protocols and sampling plans may be developed that 

meet the unique needs of the incident; and

• subsurface dispersants may be approved on an incident-specific basis as requested by 

the USCG On-Scene Commander.

More robust documentation of dispersant usage may be required. This documentation would include 

daily reports that contain the products used, the specific time and locations of application, equipment used 

for each application, spotter aircraft reports, photographs, vessel data, and analytical data. In addition to 

dispersants, controlled burns may also occur. It is estimated that 5-10 controlled burns would be 

conducted per day in suitable weather. About 500 burns in all would remove 5-10 percent of the oil.

B.2.2.7.2. Deep Water

The following are estimates for the deployment of equipment and personnel during a deepwater spill 

response. Within the first week of an oil spill originating in deep water, 50 vessels are estimated to 

respond, which would steadily increase to over 7,000 by the end of the spill. This includes about 

25 skimmers in the vicinity of the well at a time. In addition, recovered oil may be shuttle tankered to 

shore from recovery vessels. For an oil spill in deep water, over 1,000 responders are estimated to be 

deployed within the first week, which would steadily increase up to 50,000 before capping or killing the 

well within 4-5 months. Over 20,000 ft (6,096 m) of boom is estimated to be deployed within the first 

week of a deepwater spill, which would steadily increase up to 11 million feet (~2,100 mi; ~3,350 km) 

offshore and nearshore. The amount of boom would be dependent upon the location of the potentially 

impacted shoreline, environmental considerations, and agreed upon protection strategies involving the 

local potentially impacted communities. Up to 50 planes and 100 helicopters are estimated to respond per 

day by the end of a deepwater spill.

With the exception of special Federal management areas or designated exclusion areas, dispersants

have been preapproved in the vicinity of a deepwater blowout (U.S. Dept. of Homeland Security, CG, 

2010). However, USEPA is presently examining these preapprovals, and restrictions are anticipated 

regarding the future use of dispersants as a result. No preapproval presently exists for the use of subsea 

dispersants, and approval must be obtained before each use of this technology. The use of subsea 

dispersants depends on the location of the blowout, as discussed in Table B-1. Aerial dispersants are 

usually applied from airplanes as a mist, which settles on the oil on the water’s surface. Major spills that 

are continuous and uncontrollable for periods greater than 7 days and the approval of subsurface 

dispersant application are presently subject to the guidance outlined in USEPA’s letter dated December 2, 

2010. This letter provides interim guidance on the use of dispersants for major spills and outlines 

exceptions to the current preapprovals until they are updated, as discussed more fully in Chapter 

B.2.2.7.1. For a deepwater spill, dispersant application may be a preferred response in the open-water 

environment to prevent oil from reaching a coastal area, in addition to mechanical response. However, 

the window of opportunity for successful dispersant application may be somewhat narrower for some 

deepwater locations depending on the physical and chemical properties of the oil, which tend to be 

somewhat heavier or more likely to emulsify than those found closer to shore. A significant reduction in 

the window of opportunity for dispersant application may render this response option ineffective.

In addition to dispersants, controlled burns may also occur. It is estimated that 5-10 controlled burns 

would be conducted per day in suitable weather. About 500 burns in all would remove 5-10 percent of 

the oil.

B.2.2.7.3. Vessel Decontamination Stations

To avoid contaminating inland waterways, multiple vessel decontamination stations may be 

established offshore in Federal and State waters. The selected locations to conduct decontamination of 

oiled vessels will, due to the unique aspects of each spill response, be decided by the Unified Command 

during the spill response effort. Since the Unified Command includes representatives of the affected 
B-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

state(s), the states will have a prominent voice regarding whether a location in State waters will be 

acceptable.

Vessels responding to the spill and commercial and recreational vessels passing through the spill 

would anchor, awaiting inspection. If decontamination is required, work boats would use fire hoses to 

clean oil from the sides of the vessels. This could result in some oiling of otherwise uncontaminated 

waters. While these anchorage areas would be surveyed for buried pipelines that could be ruptured by 

ship anchors, they may not be surveyed adequately for benthic communities or archaeological sites. 

Therefore, some damage to benthic communities or archaeological sites may occur because of vessel 

decontamination activities associated with an oil spill (Alabama State Port Authority, 2010; State of 

Florida, Office of the Governor, 2010; Nodar, 2010; Unified Incident Command, 2010a-c; USDOC, 

NOAA, 2010a; USEPA, 2012).

B.2.2.8. Severe Weather

A hurricane could accelerate biodegradation, increase the area affected by the spill, and slow or stop 

the response effort. The movement of oil would depend on the track, wind speed, and size of a hurricane. 

The official Atlantic hurricane season runs from June 1st through November 30th, with a peak of 

hurricane probability in September. In an average Atlantic season, there are 11 named storms,

6 hurricanes, and 2 Category 3 or higher storms (USDOC, NOAA, National Weather Service, 2010). As 

a result of a hurricane, high winds and seas would mix and weather the oil from an oil spill. This can help 

accelerate the biodegradation process (USDOC, NOAA, National Weather Service, 2012). The high 

winds may distribute oil over a wider area (USDOC, NOAA, National Weather Service, 2012). 

Weather has been recognized as one of the most important factors in predicting oil-spill fate and 

behavior and in predicting the success of an oil-spill response. During an oil spill, booms, skimmers, oil 

burn, and the use of dispersants have been used to remove oil from the water surface. Adverse weather 

conditions will affect the use, performance and effectiveness of booms and skimmers. Skimmers work 

best in calm wind; for wave heights greater than 1 m (3 ft), some skimmers will not work effectively. 

Conventional booms will not work at a current velocity of 0.5 meters per second (m/sec) (1.6 feet per 

second [ft/sec]) or greater. For oil burn, ignition cannot be carried out at wind speeds greater than 

10 m/sec (33 ft/sec). The minimum wind speed for dispersant use is about 5 m/sec (16 ft/sec), and the 

maximum wind speed for the limit of dispersant applications is about 12-14 m/sec (39-46 ft/sec) (Fingas, 

2004).

There are tradeoffs in deciding where and when to place boom because, once deployed, boom is time 

consuming to tend and to relocate. As previously noted, booming operations are sensitive to wind, wave, 

and currents, and those sections of boom need to be tethered and secured to keep them from moving. 

Furthermore, it was discovered during the Deepwater Horizon explosion, oil spill, and response that hard 

boom often did more damage than anticipated in the marsh it was intended to protect after weather 

conditions ended up stranding the boom back into the marsh. Due to time constraints prior to a hurricane

event, it is therefore unlikely that much effort could be expended to move large amounts of deployed 

boom, particularly given the effort that would be required to move skimming equipment to safer locations 

inland and to move large numbers of response personnel to safer areas. However, since the conditions for 

each spill response are unique, these considerations would be examined and a site-specific hurricane 

response plan developed during the actual spill response effort by the Unified Command at the beginning 

of the official hurricane season.

In addition, adverse weather would reduce ability to respond to the spill and could result in delayed 

transport and placement of the capping stack. The action of wind on the water surface will generate 

waves. Typically, waves greater than 3 ft (1 m) will prevent smaller vessels from skimming in offshore 

waters; waves greater than 5 ft (1.5 m) will prevent even the larger vessels from getting offshore to skim. 

The new high-speed skimmers under development are very promising; some skimmers have recovered oil 

with wave heights of up to 10 ft (3 m) with corresponding winds of up to 15 m/sec (49 ft/sec).

In the event of a hurricane, vessels would evacuate the area, delaying response efforts, including the 

drilling of relief wells and any well capping or collection efforts. Severe weather, such as a hurricane, 

would delay the transport and placement of the capping stack. If a cap is applied and oil is flowed to a 

collection vessel, severe weather would cause the collection vessel to vacate its location and the oil would 

flow until the collection vessel could return and resume collection. Severe weather could also require that 

response assets be relocated inland. The response would be delayed because following the severe weather 
Catastrophic Spill Event Analysis B-11

event the assets would need to be transported back to the staging areas. The speed with which the assets 

could be brought back to the locations would depend upon on the condition of the roads and bridges for 

traffic resumption and the amount of debris potentially blocking the roads.

B.2.3. Phase 3—Onshore Contact

B.2.3.1. Duration

The duration of shoreline oiling is measured from initial shoreline contact until the well is capped or 

killed and the remaining oil dissipates offshore. The time needed to cap or kill a well may vary, 

depending on, among other things, the well’s water depth, its location, the well and geologic formation 

characteristics, and the associated debris. Depending on the spill’s location in relation to winds and 

currents and the well’s distance to shore, oil could reach the coast within 1 week to 1 month, based on 

evidence from previous spills in the Gulf of Mexico OCS (e.g., it was nearly 4 weeks after the Macondo

well blowout and spill). While it is assumed that the majority of spilled oil would dissipate offshore 

within 30-60 days of stopping the flow, some oil may remain in coastal areas for some time after a spill, 

as was observed along the Gulf Coast following the Macondo well blowout and spill. 

B.2.3.1.1. Shallow Water

Due to the distance from shore, oil spilled as a result of a blowout in shallow water could reach shore 

within 1-3 weeks and could continue until the well is killed or capped and the oil dissipates offshore. 

Therefore, it is estimated that initial shoreline oiling would likely occur for 2-5 months following a 

catastrophic blowout. Some shoreline areas could be re-oiled during this timeframe dependent upon the 

weather conditions at the time of the spill as well as the persistence of the spilled oil.

B.2.3.1.2. Deep Water

Intervention is more difficult and would take longer in deeper water, in part, because at these water 

depths these intervention efforts are conducted by remotely operated vehicles. In general, most of the 

deep water in the Gulf of Mexico is located farther from shore and, therefore, it is assumed that oil would 

reach shore within 2-4 weeks. However, for the few deepwater areas that are located closer to shore, such 

as in the Mississippi Canyon Area, the amount of estimated time until shoreline contact could be the same 

as the shallow-water scenario above (1-3 weeks). The length of shoreline oiled would continue to 

increase and previously oiled areas could be re-oiled until the well is killed or capped (3-4 months) and 

the oil dissipates offshore (1-2 months). Therefore, initial shoreline oiling could occur from 3 months up 

to 6 months following a catastrophic blowout. Persistent shoreline oiling is discussed in Chapter B.2.4

(Phase 4) below.

B.2.3.2. Volume of Oil Contacting Shore

In the event of a catastrophic spill, not all of the oil spilled would contact shore. The amount of oil 

recovered and chemically or naturally dispersed would vary. For example, the following are recovery and 

cleanup rates from previous high-volume, extended spills: 

• 10-40 percent of oil recovered or cleaned up (including burned, chemically dispersed, 

and skimmed);

• 25-40 percent of oil naturally dispersed, evaporated, or dissolved; and

• 20-65 percent of the oil remains available for offshore or inshore contact.

In the case of the Macondo well blowout and spill, the “expected” scenario, developed by the Oil 

Budget Calculator Science and Engineering Team of The Federal Interagency Solutions Group, suggests 

that more than one quarter (29%) was naturally or chemically dispersed into Gulf waters, while burning, 

skimming, and direct recovery from the wellhead removed one quarter (25%) of the oil released. Less 

than one quarter (23%) of the total oil naturally evaporated or dissolved. The residual amount, just under 
B-12 Central Planning Area Lease Sales 235, 241, and 247 EIS

one quarter (23%), remained in the Gulf of Mexico as a light sheen or as tarballs that have washed ashore 

or are buried in sand and other sediments (The Federal Interagency Solutions Group, 2010).

For planning purposes, USCG estimates that 5-30 percent of oil will reach shore in the event of an 

offshore spill (33 CFR part 154, Appendix C, Table 2). Using the USCG assumptions, a catastrophic spill 

could result in a large amount of oil reaching shore.

B.2.3.3. Length of Shoreline Contacted

While larger spill volumes increase the chance of oil reaching the coast, other factors that influence 

the length and location of shoreline contacted include the duration of the spill and the well’s location in 

relation to winds, currents, and the shoreline. Depending upon winds and currents throughout the spill 

event, already impacted areas could be re-oiled. As seen with the Deepwater Horizon oil spill, as the spill

continued, the length of oiled shoreline at any one time increased by orders of magnitude as follows:

Duration of Spill Length of Shoreline Oiled1

30 days 0-50 miles

60 days 50-100 miles

90 days 100-1,000 miles

120 days >1,000 miles2

1 Not cumulative.

2 Length was extrapolated.

Source: Operational Science Advisory Team, 2011.

B.2.3.3.1. Shallow Water

While a catastrophic spill from a shallow-water blowout is expected to be lower in volume than a 

deepwater blowout, as explained in Chapter B.2.2.3, the site would typically be closer to shore, allowing 

less time for oil to be weathered, dispersed, and recovered. This could result in a more concentrated and 

toxic oiling of the shoreline.

B.2.3.3.2. Deep Water

While a catastrophic spill from a deepwater blowout is expected to have a much greater volume than 

a shallow-water blowout (refer to Chapter B.2.2.3), the site would typically be farther from shore, 

allowing more time for oil to be weathered, dispersed, and recovered. This could result in broader, 

patchier oiling of the shoreline.

Translocation of the spilled oil via winds and currents is also a factor in the length of shoreline 

contacted. For example, oil could enter the Loop Current and then the Gulf Stream. However, the longer 

it takes oil to travel, the more it would degrade, disperse, lose toxicity, and break into streamers and 

tarballs (USDOC, NOAA, Office of Response and Restoration, 2010d).

B.2.3.4. Severe Weather

The official Atlantic hurricane season runs from June 1st through November 30th, with a peak in 

hurricane probability in September. In an average Atlantic season, there are 11 named storms, 

6 hurricanes, and 2 Category 3 or higher storms (USDOC, NOAA, National Weather Service, 2010). In 

the event of a hurricane, vessels would evacuate the area, delaying response efforts, including the drilling 

of relief wells. The storm surge may push oil to the coastline and inland as far as the surge reaches, or the 

storm surge may remove the majority of oil from shore, as seen in some of the previous spills reviewed.

Movement of oil during a hurricane would depend greatly on the track of the hurricane in relation to 

the slick. A hurricane’s winds rotate counter-clockwise. In general, a hurricane passing to the west of the 

slick could drive oil to the coast, while a hurricane passing to the east of the slick could drive the oil away 

from the coast.

Severe weather may distribute spilled oil over a wide area. Storm surge may carry oil into the coastal 

and inland waters and shore. Debris resulting from severe weather may be contaminated by oil. Thus, 
Catastrophic Spill Event Analysis B-13

the responders need to take proper precautions if weathered oil is present. Weather that results in waves 

greater than 3 ft (1 m) prevents skimming in coastal waters so there is greater likelihood of contact with 

the shoreline. Severe weather would also displace or destroy shoreline boom so that oil could come into 

contact with the shoreline until responders put the boom back in place. Severe weather could require that 

assets be relocated inland. The response would be delayed because following the severe weather event 

the assets would need to be transported back to the staging areas. The speed with which the assets could 

be brought back to the locations would depend upon on the condition of the roads and bridges for traffic 

resumption and the amount of debris potentially blocking the roads.

The USEPA, USCG, other Federal response agencies, and applicable State agencies would work 

together to address oil spills reported to the National Response Center or reported by emergency 

responders before, during, or after a hurricane occurs. Response personnel will cleanup significant spills

and take other actions appropriate to protect public health and the environment. This response would 

cover any OCS spills that may occur as a result of the hurricane or preexisting at the time of the 

hurricane. Response activities may be interrupted or complicated during a hurricane event. Oil from an 

ongoing OCS spill event may be washed ashore during a hurricane event; could be weathered, diluted, or 

washed farther inland; and could be mixed with other contaminants from other sources released during a 

hurricane event (e.g., heating oil or industrial chemicals). For example, onshore sources account for most 

of the oil spilled during the past few hurricane seasons that has resulted in oiled property. After 

Hurricane Sandy, some oil heating tanks flooded and caused oiling of a property owner’s own building(s). 

As such, depending on circumstances, a hurricane event during an OCS spill event could complicate and 

exacerbate spill impacts and response operations, but could also increase weathering and dilution.

B.2.3.5. Onshore Cleanup Activities

A large-scale response effort would be expected for a catastrophic blowout. The number of vessels 

and responders would increase steadily as the spill continued. In addition to the response described in 

Chapter B.2.2.7, the following response is also estimated to occur once the spill contacts the shore.

B.2.3.5.1. Shallow Water

• There would be 5-10 staging areas established.

• Weathering permitting, about 200-300 skimmers could be deployed near shore to 

protect coastlines.

B.2.3.5.2. Deep Water

• There would be 10-20 staging areas established.

• Weather permitting, about 500-600 skimmers could be deployed near shore to protect 

coastlines. As seen in Louisiana following the Macondo well blowout and spill, a 

few hundred coastal skimmers could still be in operation a few months after the well 

is capped or killed (The State of Louisiana, 2010).

B.2.3.5.3. Response Considerations for Sand Beaches for Both Shallow-Water and 

Deepwater Spills

• No mechanical techniques allowed in some areas.

• Surface residence balls (SRB’s), also commonly known as tarballs, and surface 

residence patties (SRP’s) are subject to smearing during the day; therefore, much of 

the beach cleanup can be expected to be conducted at night, if the weather is warm.

• There are marked differences in the sediments on the central Louisiana coast as 

compared with the Gulf beaches of Alabama, Florida, and Mississippi; therefore, no 

single technique will be universally applicable for cleaning sand beaches.
B-14 Central Planning Area Lease Sales 235, 241, and 247 EIS

• Typically, sand sieving, shaking, and sifting beach cleaning machines will be 

utilized. The depth of cut below the sand surface can be expected to typically range 

from 0 to 12 inches (in) (0 to 30 centimeters [cm]) when using this equipment.

• It is anticipated that the responders will be instructed that no disturbance will be 

allowed below 18 in (46 cm). However, oil can be expected down to a depth of 

24-26 in (61-66 cm) below the sand surface.

• Repetitive tilling and mixing may be used at beaches such as Grand Isle, using 

agriculture plows and discs in combination with beach cleaning machines. Sand 

washing treatment also may take place at beaches such as Grand Isle’s beach. Sand 

washing includes a sand sieve/shaker to remove debris and large oil particles and a 

heated washing system. Average daily throughput for these systems would be 

290 cubic yards per day. Sand treated in this manner is typically treated by sediment 

relocation, which is where the sand is moved to an active intertidal zone

B.2.3.5.4. Response Considerations for Marshes for Both Shallow-Water and 

Deepwater Spills

• Lightly oiled marsh may be allowed to recover naturally; the oil may be allowed to 

degrade in place or to be removed by tidal or wave action.

• Moderately or heavily oiled marsh could be cleaned by vacuuming or skimming from 

boats in conjunction with flushing to enhance oil recovery rates, low pressure 

flushing (with water comparable to marsh type), manual removal by hand or 

mechanized equipment, or vegetation cutting.

• In some heavily oiled areas, in-situ burning may be an option if water covers the 

sediment surface. This technique is only considered when the source is contained 

due to potential re-oiling of the area. Surface washing agents are also a technique 

that might be utilized.

• Bioremediation may be utilized but mostly as a secondary treatment after bulk 

removal.

B.2.3.5.5. Response Considerations for Nearshore Waters for Both Shallow-Water 

and Deepwater Spills

• Nearshore submerged oil is difficult to recover and hard to locate; vacuums and 

snares could be used.

• In the vicinity of marsh areas, skimming techniques with flushing could be utilized 

where warranted. In areas too shallow to use skimmers, oil removal could be 

accomplished using vacuum systems, in conjunction with flushing as needed. 

Booming could also be used to temporarily contain mobile slicks until they are 

recovered.

B.2.4. Phase 4—Post-Spill, Long-Term Recovery

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been 

capped or killed and that cleanup activities are concluding. While it is assumed that the majority of 

spilled oil floating on surface waters would be dissipated within 30-60 days of stopping the flow, oil has 

the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill (USDOI, FWS, 2004). On sandy beaches, oil can sink deep into the sediments. In 

tidal flats and salt marshes, oil may seep into the muddy bottoms (USDOI, FWS, 2010a). As of this 

writing, residual oil can still be found in Louisiana marshes and oil still sporadically appears as tarballs 

and tar patties on Alabama and Florida beaches following the Deepwater Horizon explosion, oil spill, and 
Catastrophic Spill Event Analysis B-15

response in 2010. In addition, oil may still reside in deeper waters in sediments within close proximity of 

the wellhead, where response cleanup activities may not be pursued (OSAT, 2010).

If a shoreline is oiled, the selection of the type of shoreline remediation to be used will depend on the 

following: (1) the type and amount of oil on the shore; (2) the nature of the affected coastline; (3) the 

depth of oil penetration into the sediments; (4) the accessibility and the ability of vehicles to travel along 

the shoreline; (5) the possible ecological damage of the treatment to the shoreline environment; 

(6) weather conditions; (7) the current state of the oil; and (8) jurisdictional considerations. To determine 

which cleanup method is most appropriate during a spill response, decisionmakers must assess the 

severity and nature of the injury using Shoreline Cleanup and Assessment Team survey observations. 

These onsite decisionmakers must also estimate the time it will take for an area to recover in the absence 

of cleanup (typically considering short term to be 1-3 years, medium term to be 3-5 years, and long term 

greater than 5 years) (National Response Team, 2010).

B.2.4.1. Response Considerations for Sand Beaches, Marshes, and Nearshore 

Waters for both Shallow-Water and Deepwater Spills

Once oiled, it can be expected that the shoreline response techniques employed in the initial phase of 

a response will become more extensive and continue for some time (Chapters B.2.3.5.3, B.2.3.5.4, and 

B.2.3.5.5). Spill response post-Macondo well blowout and spill is still ongoing in some of the more 

heavily oiled areas in Louisiana and in other areas, such as Florida and Alabama, that experience periodic 

re-oiling from submerged oil mats that lie in the inshore surf zone in troughs between the sand bars or 

from buried oil onshore that resurfaces. The three types of oil residue that have been identified as 

challenging or potentially damaging to the environment if removed includes the following: (1) supra-tidal 

buried oil (buried below the 6-in [15-cm] surface cleaning depth restriction near sensitive habitats); 

(2) small surface residual balls, which are oil residue left behind after beaches are cleaned; and (3) surf 

zone submerged oil mats. Additional information regarding shoreline response considerations can be 

found in Chapter 3.2.1.9 of this Supplemental EIS.

B.3. DESCRIPTION OF THE ENVIRONMENT AND IMPACT ANALYSIS

B.3.1. Long Duration—Large Volume Spill within the Gulf of Mexico

The following resource descriptions and impact analyses examined only the applicable portions of the 

scenario (described fully in Chapter 3 and summarized in Table B-4). 

B.3.1.1. Air Quality

Phase 1—Initial Event

A catastrophic blowout close to the water surface would initially emit large amounts of methane and 

other gases into the atmosphere. If high concentrations of sulfur are present in the produced gas, 

hydrogen sulfide (H2S) could present a hazard to personnel. The natural gas H2S concentrations in the 

Gulf of Mexico OCS are generally low; however, there are areas such as the Norphlet formation in the 

northeastern Gulf of Mexico, for example, that contain levels of H2S up to 9 percent. Ignition of the 

blowout gas and subsequent fire would result in emissions of nitrogen oxides (NOx), sulfur oxides (SOx), 

carbon monoxide (CO), volatile organic compounds (VOC’s), particulate matter (PM10), and fine 

particulate matter (PM2.5). The fire could also produce polycyclic aromatic hydrocarbons (PAH’s), which 

are known to be hazardous to human health. The pollutant concentrations would decrease with downwind 

distance. A large plume of black smoke would be visible at the source and may extend a considerable 

distance downwind. However, with increasing distance from the fire, the gaseous pollutants would 

undergo chemical reactions, resulting in the formation of fine particulate matter (PM2.5) that includes 

nitrates, sulfates, and organic matter. The PM2.5 concentrations in the plume would have the potential to 

temporarily degrade visibility in any affected Prevention of Significant Deterioration (PSD) Class I areas 

(i.e., National Wilderness Areas and National Parks) and other areas where visibility is of significant 

value. Organic aerosols formed downwind from the Macondo well blowout and spill (de Gouw et al., 

2011), during which the lightest compounds, the VOC’s, in the oil from the Macondo well blowout and 
B-16 Central Planning Area Lease Sales 235, 241, and 247 EIS

spill evaporated within hours and during which the heavier compounds took longer to evaporate, 

contributing to the formation of air pollution particles downwind.

Phase 2—Offshore Spill

In the Gulf of Mexico, evaporation from the oil spill would result in concentrations of VOC’s in the 

atmosphere, including chemicals that are classified as being hazardous. The VOC concentrations would 

occur anywhere where there is an oil slick, but they would be highest at the source of the spill because the 

rate of evaporation depends on the volume of oil present at the surface. The VOC concentrations would 

decrease with distance as the layer of oil gets thinner. The lighter compounds of VOC’s would be most 

abundant in the immediate vicinity of the spill site. The heavier compounds would be emitted over a 

longer period of time and over a larger area. Some of the compounds emitted could be hazardous to 

workers in close vicinity of the spill site. The hazard to workers can be reduced by monitoring and using 

protective gear, including respirators, as well as limiting exposure through limited work shifts, rotating 

workers in close vicinity of the spill site. The hazard to workers can be reduced by monitoring and using 

protective gear, including respirators, as well as limiting exposure through limited work shifts, rotating 

workers out of high exposure areas, and pointing vessels into the wind. During the Macondo well 

blowout and spill, air samples collected by individual offshore workers of British Petroleum (BP), the 

Occupational Safety and Health Administration (OSHA), and USCG showed levels of benzene, toluene, 

ethylbenzene, and xylene that were mostly under detection levels. All samples had concentrations below 

the OSHA permissible exposure limits and the more stringent ACGIH (American Conference of 

Governmental Industrial Hygienists) threshold limit values (U.S. Dept. of Labor, OSHA, 2010a).

The VOC emissions that result from the evaporation of oil contribute to the formation of particulate 

matter (PM2.5) in the atmosphere. In addition, VOC’s could cause an increase in ozone levels, especially 

if the release were to occur on a hot, sunny day with sufficient concentrations of NOx present in the lower 

atmosphere. However, because of the distance of the proposed CPA lease sale area from shore, the oil 

slick would not likely have any effects on onshore ozone concentrations; however, if there were any 

effects to onshore ozone concentrations, they would be likely only be temporary in nature and last at most 

the length of time of the spill duration. 

It is assumed that response efforts would include hundreds of in-situ or controlled burns, which would 

remove an estimated 5-10 percent of the volume of oil spilled. This could be as much as 720,000 bbl of 

oil for a spill of 60,000 bbl per day for 90 days. In-situ burning would result in ambient concentrations of 

CO, NOx, SO2, PM10, and PM2.5 very near the site of the burn and would generate a plume of black 

smoke. The levels of PM2.5 could be a hazard to personnel working in the area, but this could be 

effectively mitigated through monitoring and relocating vessels to avoid areas of highest concentrations. 

In an experiment of an in-situ burn off Newfoundland, it was found that CO, SO2, and NO2 were 

measured only at background levels and were frequently below detection levels (Fingas et al., 1995). 

Limited amounts of formaldehyde and acetaldehyde were measured, but concentrations were close to 

background levels. Measured values of dioxins and dibenzofurans were at background levels. 

Measurements of PAH in the crude oil, the residues, and the air indicated that the PAH in the crude oil are 

largely destroyed during combustion (Fingas et al., 1995).

While containment operations may be successful in capturing some of the escaping oil and gas, 

recovery vessels may not be capable of storing the crude oil or may not have sufficient storage capacity. 

In this case, excess oil would be burned; captured gas cannot be stored or piped to shore so it would be 

flared. For example, in the Macondo well blowout and spill, gas was flared at the rate of 100-200 million 

cubic feet per day and oil burned at the rate of 10,000-15,000 bbl per day. The estimated NOx emissions 

are about 13 tons per day. The SO2 emissions would be dependent on the sulfur content of the crude oil. 

For crude oil with a sulfur content of 0.5 percent, the estimated SO2 emissions are about 16 tons per day. 

Particulate matter in the plume would also affect visibility. Flaring or burning activities upwind of a PSD 

Class I area, e.g., the Breton National Wilderness Area, could adversely affect air quality there because of 

increased levels of SO2, PM10, and PM2.5, and because of reduced visibility.

Phase 3—Onshore Contact

As the spill nears shore, there would be low-level concentrations of odor-causing pollutants 

associated with evaporative emissions from the oil spill. These may cause temporary eye, nose, or throat 
Catastrophic Spill Event Analysis B-17

irritation, nausea, or headaches, but the doses are not thought to be high enough to cause long-term harm 

(USEPA, 2010b). However, responders could be exposed to levels higher than OSHA occupational 

permissible exposure levels (U.S. Dept. of Labor, OSHA, 2010b). During the Deepwater Horizon

explosion, oil spill, and response, USEPA took air samples at various onshore locations along the length 

of the Gulf coastline. All except three measurements of benzene were below 3 parts per billion (ppb). 

The highest level was 91 ppb. Emissions of benzene to the atmosphere result from gasoline vapors, auto 

exhaust, and chemical production and user facilities. Ambient concentrations of benzene up to and 

greater than 5 ppb have been measured in industrial areas such as Houston, Texas; in various urban areas 

during rush hour; and inside the homes of smokers (U.S. Dept. of Human and Health Services, 2007). 

The following daily median benzene air concentrations were reported in the Volatile Organic Compound 

National Ambient Database (1975-1985): remote (0.16 ppb); rural (0.47 ppb); suburban (1.8 ppb); urban 

(1.8 ppb); indoor air (1.8 ppb); and workplace air (2.1 ppb). The outdoor air data represent 300 cities in 

42 states, while the indoor air data represent 30 cities in 16 states (Shah and Singh, 1988).

During the Deepwater Horizon explosion, oil spill, and response, air samples collected by BP, 

OSHA, and USCG near shore showed levels of benzene, toluene, ethylbenzene, and xylene that were 

mostly under detection levels. Among the 28,000 personal benzene samples taken by BP, there was only 

1 sample where benzene exceeded the OSHA occupational permissible exposure limits, and 6 additional 

validated constituents were in excess of the ACGIH threshold limit value. All other sample 

concentrations were below the more stringent ACGIH threshold limit values (U.S. Dept. of Labor, 

OSHA, 2010a). All measured concentrations of toluene, ethylbenzene, and xylene were well within the 

OSHA occupational permissible exposure levels and ACGIH threshold limit values.

Phase 4—Post-Spill, Long-Term Recovery and Response

There would be some residual air quality impacts after the well is capped or killed. As most of the oil 

would have been burned, evaporated, or weathered over time, air quality would return to pre-oil spill

conditions. While impacts to air quality are expected to be localized and temporary, adverse effects that 

may occur from the exposure of humans and wildlife to air pollutants could have long-term consequences.

Overall Summary and Conclusion (Phases 1-4)

The OCS oil- and gas-related catastrophic event could include the release of oil, condensate, or 

natural gas or chemicals used offshore or pollutants from the burning of these products. The air pollutants 

include criteria National Ambient Air Quality Standards (NAAQS) pollutants, volatile and semi-volatile 

organic compounds, H2S, and methane. If a fire was associated with the event, it would produce a broad 

array of pollutants, including all NAAQS-regulated primary pollutants, including NO2, CO, SOx, VOC,

PM10, and PM2.5. Response activities that could impact air quality include in-situ burning, the use of 

flares to burn gas and oil, and the use of dispersants applied from aircraft. Measurements taken during an 

in-situ burning show that a major portion of compounds was consumed in the burn; therefore, pollutant 

concentrations would be expected to be within the NAAQS. In a recent analysis of air in coastal 

communities, low levels of dispersant components, which are also used in everyday household products, 

were identified. These response activities are temporary in nature and occur offshore; therefore, there are 

little expected impacts from these actions to onshore air quality. Catastrophic events involving high 

concentrations of H2S could result in deaths as well as environmental damage. Regulations and NTL’s 

mandate safeguards and protective measures, which are in place, to protect workers from H2S releases. 

Other emissions of pollutants into the atmosphere from catastrophic events are not projected to have 

significant impacts on onshore air quality because of the prevailing atmospheric conditions, emissions 

height, emission rates, and the distance of these emissions from the coastline.

Overall, since loss of well-control events, blowouts, and fires are rare events and of short duration, 

potential impacts to air quality are not expected to be significant except in the rare case of a catastrophic 

event. To date, air monitoring conducted following the Macondo well blowout and spill, has not found 

any pollutants at levels expected to cause long-term harm (USEPA, 2010a). 
B-18 Central Planning Area Lease Sales 235, 241, and 247 EIS

B.3.1.2. Water Quality

Phase 1—Initial Event

Offshore Water Quality

During the initial phase of a catastrophic blowout, water quality impacts include the disturbance of 

sediments and the release and suspension of oil and natural gas (primarily methane) into the water 

column. These potential impacts are discussed below. As this chapter deals with the immediate effects of 

a blowout that would be located at least 3 nmi (3.5 mi; 5.6 km) from shore, it is assumed that there would 

be no impacts on coastal water quality during this initial stage.

Disturbance of Sediments

A catastrophic blowout below the seafloor, outside the wellbore (Table B-1) has the potential to 

resuspend sediments and disperse potentially large quantities of bottom sediments. Some sediment could 

travel several kilometers, depending on particle size and subsea current patterns. In the deep Gulf of 

Mexico, surficial sediments are mostly composed of silt and clay, and, if resuspended, could stay in the 

water column for several hours to days. Bottom current measurements in the deep Gulf of Mexico were 

synthesized as part of the MMS Deepwater Reanalysis study and have been measured to reach 

90 centimeters/second (cm/sec) (35.4 inches/second [in/sec]) with mean flows of 0.4-21 cm/sec 

(0.2-8.3 in/sec) (Nowlin et al., 2001). At these mean flow rates, resuspended sediment could be 

transported 0.3-18 km per day (0.2-11 mi per day).

Sediment resuspension can lead to a temporary change in the oxidation-reduction chemistry in the 

water column, including a localized and temporal release of any formally sorbed metals, as well as 

nutrient recycling (Caetano et al., 2003; Fanning et al., 1982). Sediments also have the potential to 

become contaminated with oil components.

A subsea release also has the potential to destabilize the sediments and create slumping or larger scale 

sediment movements along depth gradients. These types of events would have the potential to move 

and/or damage any infrastructure in the affected area.

Release and Suspension of Oil into the Water Column

A subsea release of hydrocarbons at a high flow rate has the potential to disperse and suspend plumes 

of oil droplets (chemically dispersed or otherwise) within the water column and to induce large patches of 

sheen and oil on the surface. These dispersed hydrocarbons may adsorb onto marine detritus (marine 

snow), suspended sediments, or may be mixed with drilling mud and deposited near the source. 

Mitigation efforts such as burning may introduce hydrocarbon byproducts into the marine environment, 

which would be distributed by surface currents. The acute and chronic sublethal effects of these dilute 

suspended “plumes” are not well understood and require future research efforts.

As a result of the Macondo well blowout and spill, a subsurface oil and gas plume was discovered in 

deep waters between ~1,100 and 1,300 m (3,609 and 4,265 ft) (e.g., Diercks et al., 2010) in addition to the 

surface slick. Measurable amounts of hydrocarbons (dispersed or otherwise) were detected in the 

subsurface plumes and on the seafloor in the vicinity of the release (e.g., Diercks et al., 2010; OSAT, 

2010). In the Macondo well blowout and spill subsurface plume, half-lives were estimated for petroleum 

hydrocarbons and n-alkanes on the order of 1 month and several days, respectively, indicating the impacts 

of various weathering processes (Reddy et al., 2011 and references therein). After the Ixtoc I well 

blowout and spill in 1979, which was located 50 mi (80 km) offshore in the Bay of Campeche, Mexico, 

some subsurface oil was also observed dispersed within the water column (Boehm and Fiest, 1982); 

however, the scientific investigations were limited (Reible, 2010). The water quality of offshore waters 

would be affected by the dissolved components and oil droplets that are small enough that they do not rise 

to the surface or are mixed down by surface turbulence. In the case of subsurface oil plumes, it is 

important to remember that these plumes would be affected by subsurface currents, dilution, and natural 

physical, chemical, and biological degradation processes including weathering.

Large quantities of oil put into offshore water may alter the chemistry of the sea with unforeseeable 

results. The properties and persistence of oil, including oil in the Gulf of Mexico, is further discussed in 

Chapter B.2.2.4. The VOC’s, including benzene, toluene, ethylbenzene, and xylenes (also referred to as 
Catastrophic Spill Event Analysis B-19

BTEX), are highly soluble and can have acutely toxic effects; however, VOC’s are light-weight oil 

components and tend to evaporate rather than persist in the environment (Michel, 1992). Middle-weight 

organic components tend to pose the greatest risk in the environment because they are more persistent in 

the environment, are more bioavailable, and include polycyclic aromatic hydrocarbons (PAH’s), which 

have high toxicities (Michel, 1992). To determine the overall toxicity of PAH’s in water or sediment, the 

contributions of every individual PAH compound in the petroleum mixture must be included (USEPA, 

2011). This approach was used during the Macondo well blowout, spill and response in determining the 

potential risk of PAH’s in both water and sediment to humans or animals in the environment (OSAT, 

2010). Heavier components of crude oil tend to pose less risk of toxicity because they are not very 

soluble in water and therefore are less bioavailable.

The oil that entered the Gulf of Mexico from the Macondo well blowout and spill was a South 

Louisiana sweet crude oil (i.e., low in sulfur) (USDOC, NOAA, 2010b). This oil is less toxic than other 

crude oils in general because this oil is lower in PAH’s than many other crude oils. Studies indicate that 

the oil contained approximately 3.9 percent PAH’s by weight, which results in an estimated release of 

2.1 x 1010 grams of PAH’s (Reddy et al., 2011; Reddy, official communication, 2012). The oil was also 

fairly high in alkanes (organic compounds containing only carbon and hydrogen and single bonds, 

sometimes called paraffin or aliphatic compounds) (USDOC, NOAA, 2010b). Because alkanes are 

simple hydrocarbons, these oils are likely to undergo biodegradation more easily (USDOC, NOAA, 

2010b).

Release of Natural Gas (Methane) into the Water Column

A catastrophic blowout could release natural gas into the water column; the amount of gas released is 

dependent upon the water depth, the natural gas content of the formation being drilled, and its pressure. 

Methane is the primary component of natural gas. Methane may stay in the marine environment for long 

periods of time (Patin, 1999; page 237), as methane is highly soluble in seawater at the high pressures and 

cold temperatures found in deepwater environments (NRC, 2003; page 108). However, methane 

diffusing through the water column would likely be oxidized in the aerobic zone and would rarely reach 

the air-water interface (Mechalas, 1974; page 23). In addition to methane, natural gas contains smaller 

percentages of other gases such as ethane, propane, and to a much lesser degree H2S (NaturalGas.org, 

2012), which can be toxic in the environment. The majority of natural gas components including methane 

are carbon sources, and their introduction into the marine environment could result in reducing the 

dissolved oxygen levels because of microbial degradation potentially creating hypoxic or “dead” zones. 

Unfortunately, little is known about methane toxicity in the marine environment, but there is concern as to 

how methane in the water column might affect fish. Further discussion of natural gas released during the 

Macondo well blowout and spill is given in Chapter B.2.2.5.

Phase 2—Offshore Spill

Offshore Water Quality

The water offshore of the Gulf’s coasts can be divided into two regions: the continental shelf and 

slope (<1,000 ft; 305 m) and deep water (>1,000 ft; 305 m). Waters on the continental shelf and slope are 

heavily influenced by the Mississippi and Atchafalaya Rivers, the primary sources of freshwater, 

sediment, nutrients, and pollutants from a huge drainage basin encompassing 55 percent of the continental 

U.S. (Murray, 1998). Lower salinities are characteristic nearshore where freshwater from the rivers mix 

with Gulf waters. The presence or extent of a nepheloid layer, a body of suspended sediment at the sea 

bottom (Kennett, 1982, page 524), affects water quality on the shelf and slope. Deep waters east of the 

Mississippi River are affected by the Loop Current and associated warm-core (anti-cyclonic) eddies, 

which flush the area with clear, low-nutrient water (Muller-Karger et al., 2001) (Figure B-2). However, 

cold-core cyclonic eddies (counter-clockwise rotating) also form at the edge of the Loop Current and are 

associated with upwelling and nutrient-rich, high-productivity waters, although the extent of this flushing 

can vary seasonally.

While response efforts would decrease the fraction of oil remaining in Gulf waters, significant 

amounts of oil would remain. Natural processes will physically, chemically, and biologically aid the 

degradation of oil (NRC, 2003). The physical processes involved include evaporation, emulsification, 

and dissolution, while the primary chemical and biological degradation processes include photo-oxidation 
B-20 Central Planning Area Lease Sales 235, 241, and 247 EIS

and biodegradation (i.e., microbial oxidation). Water quality would not only be impacted by the oil, gas, 

and their respective components, but also to some degree, from cleanup and mitigation efforts, such as 

from increased vessel traffic and the addition of dispersants and methanol to the marine environment.

In the case of a catastrophic subsea blowout in deep water, it is assumed that large quantities of 

subsea dispersants would be used. The positive effect of using dispersants is that the oil, once dispersed, 

may be more available to be degraded (however, we note that contrary findings for beached oil were 

presented by Hamdan and Fulmer, 2011). The negative effect is that the oil, once dispersed, is also more 

bioavailable to have toxic effects to microorganisms as well. The toxicity of dispersed oil in the 

environment would depend on many factors, including the effectiveness of the dispersion, temperature, 

salinity, degree of weathering, type of dispersant, and degree of light penetration in the water column 

(NRC, 2005). The toxicity of dispersed oil is primarily because of the toxic components of the oil itself 

(Australian Maritime Safety Authority, 2010).

As a result of the use of dispersants, it would be more likely for clouds or plumes of dispersed oil to 

occur near the blowout site as was seen during the Macondo well blowout and spill. Dissolved oxygen 

levels are a concern with any release of a carbon source, such as oil and natural gas, and became a 

particular concern during the Macondo well blowout and spill since dispersants were used in deep waters 

for the first time. In areas where plumes of dispersed oil were previously found, dissolved oxygen levels 

decreased by about 20 percent from long-term average values in the GOM of ~6.9 milligrams/liter (spring 

climatological mean at 1,500-m [4,921 -ft] depth); however, scientists reported that these levels stabilized 

and were not low enough to be considered hypoxic (Joint Analysis Group, 2010b; USDOC, NOAA, 

2010d). The drop in oxygen, which did not continue over time, has been attributed to microbial 

degradation of the oil.

Phase 3—Onshore Contact

Coastal Water Quality 

Water quality governs the suitability of waters for plant, animal, and human use. Water quality is 

important in the bays, estuaries, and nearshore coastal waters of the Gulf because these waters provide 

feeding, breeding, and/or nursery habitat for many invertebrates and fishes, as well as sea turtles, birds, 

and marine mammals. A catastrophic spill would significantly impact coastal water quality in the Gulf of 

Mexico. Water quality prior to the Macondo well blowout and spill was rated as fair while sediment 

quality was rated as poor (USEPA, 2008). In addition, the coastal habitat index, a rating of wetlands

habitat loss, was also rated as poor. Both the sediment quality and the coastal habitat index affect water 

quality.

Though response efforts would decrease the amount of oil remaining in Gulf waters and reduce the 

amount of oil contacting the coastline, significant amounts of oil would remain. Coastal water quality

would be impacted not only by the oil, gas, and their respective components but also to some degree from 

cleanup and mitigation efforts. Increased vessel traffic, hydromodification, and the addition of 

dispersants and methanol in an effort to contain, mitigate, or clean up the oil may also tax the 

environment.

The use of dispersants as a response tool involves a tradeoff. The purpose of chemical dispersants is 

to facilitate the movement of oil into the water column in order to encourage weathering and biological 

breakdown of the oil (i.e., biodegradation) (NRC, 2005; Australian Maritime Safety Authority, 2010). 

Thus, the tradeoff is generally considered to be oiling of the shoreline and surface of the water versus the 

water column and benthic resources (NRC, 2005). If the oil moves into the water column and is not on 

the surface of the water, it is less likely to reach sensitive shore areas (USEPA, 2010b). Since sea birds 

are often on the surface of the water or in shore areas, dispersants are also considered to be very effective 

in reducing the exposure of sea birds to oil (Australian Maritime Safety Authority, 2010). In addition to 

dispersion being enhanced by artificial processes, oil may also be dispersed from natural processes 

including both (bio)chemical and physical processes. For instance, microbial metabolism of crude oil 

results in the dispersion of oil (Bartha and Atlas, 1983), and conditions at the source of the oil/gas leak 

(e.g., orifice size and shape) may cause physical dispersion of the oil. Dispersion has both positive and 

negative effects. The positive effect is that the oil, once dispersed, is more available to be degraded. The 

negative effect is that the oil, once dispersed, is also more bioavailable to have toxic effects to 

microorganisms as well. For example, a recent study using mesocosm experiments suggested that 
Catastrophic Spill Event Analysis B-21

dispersed oil could disrupt coastal microbial foodwebs in the northern Gulf of Mexico, reducing the flow 

of carbon to higher trophic levels (Ortmann et al., 2012). The toxicity of dispersed oil in the environment 

will depend on many factors, including the effectiveness of the dispersion, temperature, salinity, the 

degree of weathering, type of dispersant, and the degree of light penetration in the water column (NRC, 

2005). The toxicity of dispersed oil is primarily because of the toxic components of the oil itself 

(Australian Maritime Safety Authority, 2010).

Oxygen and nutrient concentrations in coastal waters vary seasonally. The zone of hypoxia (depleted 

oxygen) on the Louisiana-Texas shelf occurs seasonally and is affected by the timing of freshwater 

discharges from the Mississippi and Atchafalaya Rivers. The hypoxic conditions continue until local 

wind-driven circulation mixes the water again. The 2010 hypoxic zone could not be linked to the 

Macondo well blowout and spill in either a positive or a negative manner (Louisiana Universities Marine 

Consortium, 2010). Nutrients from the Mississippi River nourished phytoplankton and contributed to the 

formation of the hypoxic zone.

Phase 4—Post-Spill, Long-Term Recovery and Response

The leading source of contaminants that impairs coastal water quality in the Gulf of Mexico is urban 

runoff. It can include suspended solids, heavy metals, pesticides, oil, grease, and nutrients (such as from 

lawn fertilizer). Urban runoff increases with population growth, and the Gulf Coast region has 

experienced a 109 percent population growth since 1970, with an additional expected 15 percent increase 

expected by 2020 (USDOC, NOAA, 2011). Other pollutant source categories include (1) agricultural 

runoff, (2) municipal point sources, (3) industrial sources, (4) hydromodification (e.g., dredging), and 

(5) vessel sources (e.g., shipping, fishing, and recreational boating). The NRC (2003, Table I-4, 

page 237) estimated that, on average, approximately 26,324 bbl of oil per year entered Gulf waters from 

petrochemical and oil refinery industries in Louisiana and Texas. The Mississippi River introduced 

approximately 3,680,938 bbl per year (NRC, 2003, Table I-9, page 242) into the waters of the Gulf. 

Hydrocarbons also enter the Gulf of Mexico through natural seeps in the Gulf at a rate of approximately 

980,392 bbl per year (a range of approximately 560,224-1,400,560 bbl per year) (NRC, 2003, page 191). 

Produced water (formation water) is, by volume, the largest waste stream from the oil and gas industry 

that enters Gulf waters (e.g., Table B-3). The NRC has estimated the quantity of oil in produced water 

entering the Gulf per year to be 473,000 bbl (NRC, 2003, page 200, Table D-8).1

 These sources total 

about 5.5 MMbbl of oil per year that routinely enters Gulf of Mexico waters. In comparison, a 

catastrophic spill of 30,000-60,000 bbl per day for 90-120 days would spill a total of 2.7-7.2 MMbbl of 

oil. When added to the other sources of oil listed above, this would result in a 48- to 129-percent increase 

in the volume of oil entering the water during the year of the spill. In addition, the oil from a catastrophic 

spill will be much more concentrated in some locations than the large number of other activities that 

release oil into the Gulf of Mexico. Chapter B.2.2.4 discusses the properties and persistence of oil in the 

environment.

Overall Summary and Conclusion (Phases 1-4)

During Phase 1 of the catastrophic blowout scenario, impacts are not expected to coastal water 

quality. Instead, the initial impacts will include degradation of offshore water quality, disturbance and 

degradation of sediments, and the release and suspension of oil and natural gas into the water column, 

including the possible formation of plumes. Fine sediments could be transported away from the spill site.

As the spill continues during Phase 2, response efforts and natural degradation processes would 

decrease the amount of oil in the Gulf, but significant amounts of oil would remain to impact water and 

sediment quality. Water and sediment quality would not only be impacted by the oil, gas, and their 

respective components but also to some degree from cleanup and mitigation efforts. The use of 

dispersants as a response tool may make the oil more available to degradation, but it can also make the oil 

more bioavailable to have toxic effects on microorganisms as well. Furthermore, dispersed oil is more 

likely to form a plume.

 1 These numbers were generated from converting the units reported in the noted reference and do not imply any 

level of significance.
B-22 Central Planning Area Lease Sales 235, 241, and 247 EIS

Onshore contact is made during Phase 3, so coastal sediment and water quality will be significantly 

impacted during this phase despite response efforts. Response efforts may even tax the coast to some 

degree. Natural and chemical dispersion may reduce the contact of oil with the shoreline but result in 

more oil in the water column and greater bioavailability of the dispersed oil.

The long-term recovery (Phase 4) of the water and sediment quality of the Gulf will depend on the 

properties and persistence of the oil as noted in Chapter B.2.2.4. Though the spill will increase the 

amount of oil entering the Gulf of Mexico, oil regularly enters the Gulf through sources such as oil 

refineries, the Mississippi River, produced water, and natural seeps. However, oil from a spill will be 

more concentrated than the oil input from these other sources.

B.3.1.3. Coastal Barrier Beaches and Associated Dunes

Phase 1—Initial Event

There would likely be no adverse impacts to coastal barrier beaches and associated dunes as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 1 of a

catastrophic spill event because these resources would not be contacted until the oil reached the shoreline.

Phase 2—Offshore Spill

There would likely be no adverse impacts to coastal barrier beaches and associated dunes as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 2 of a 

catastrophic spill event because these resources would not be contacted until the oil reached the shoreline.

Phase 3—Onshore Contact 

Barrier islands make up more than two-thirds of the northern Gulf of Mexico shore. Each of the 

barrier islands is either high profile or low profile, depending on the elevations and morphology of the 

island (Morton et al., 2004). The distinguishing characteristics of the high- and low-profile barriers relate 

to the width of the islands along with the continuity of the frontal dunes. Low-profile barriers are narrow 

with discontinuous frontal dunes easily overtopped by storm surge, which makes the island susceptible to 

over wash and erosion. This over wash can create channels to bring sand onto the island or into lagoons 

formed on these islands. High-profile barrier islands are generally wider than the low-profile islands and 

have continuous, vegetated, frontal dunes with elevations high enough to prevent over wash from major 

storm surge and, therefore, are less susceptible to erosion. The sand stored in these high-profile dunes 

allows the island to withstand prolonged erosion and therefore prevents breaching, which could result in 

damaging the island core.

The effects from oil spills depend on the geographic location, volume, and rate of the spill; type of 

oil; oil-slick characteristics; oceanic conditions and season at the time of the spill; and response and 

cleanup efforts. The effects could include changes in plant species diversity that could result in changes 

in forage areas for species using microfauna as a food base (Teal and Howarth, 1984). Further detail on 

this catastrophic OSRA run is contained in Appendix C. 

As a result of a catastrophic spill, many of the barrier islands and beaches would receive varying 

degrees of oiling. Oil disposal on sand and vegetated sand dunes was shown in experiments by Webb 

(1988) to have little deleterious effects on the existing vegetation or on the recolonization of the oiled 

sands by plants. However, other studies have documented toxic effects of oil on barrier beach vegetation 

(Ko and Day, 2004). The depth of oiling would be variable, based on the wave environment and 

sediment source at a particular beach head. Layering of oil and sand could occur if it was not cleaned 

before another tidal cycle. However, most areas of oiling are expected to be light, and sand removal 

during cleanup activities should be minimized. The severity of oiling dictates the appropriate cleanup 

method to be utilized (refer to Table B-4). 

In areas designated as natural wilderness areas (e.g., Breton National Wildlife Refuge and Gulf 

Islands National Seashore), land managers may require little to no disruption of the natural system. In 

these environments, it is preferred to let the oil degrade naturally without aggressive and intrusive cleanup 

procedures. Manual rather than mechanized removal techniques would be used in these areas and only if 

heavy oiling has occurred. Thus, these areas may not be treated as thoroughly as other shorelines. Oil 
Catastrophic Spill Event Analysis B-23

would remain in place longer, weathering gradually while continuing to contaminate habitat, though 

mechanical disturbance would be minimized.

Once oil has reached the beaches and barrier islands and becomes buried or sequestered, it becomes 

difficult to treat. During wave events when the islands and beaches erode, the oil can become 

remobilized and transported. Thus, the fate of oil is not as simple as either reaching land, becoming 

sequestered, or being treated; but, it must be considered in terms of a continuing process of sequestration, 

remobilization, and transport.

For spilled oil to move onto beaches or across dunes, strong southerly winds must persist for an 

extended time prior to or immediately after the spill to elevate water levels. Strong winds, however, 

could reduce the impact severity at a landfall site by accelerating the processes of oil-slick dispersal, spill 

spreading, and oil weathering.

Bik et al. (2012) found that, despite the disappearance of visible surface oil on heavily oiled Gulf 

beaches impacted by the Macondo well blowout and spill, microbial communities showed significant 

changes in community structure, with a decrease in diversity and a shift toward dominance by fungal taxa, 

particularly known hydrocarbon-degrading genera. Likewise, nematode communities showed decreased 

diversity and increased dominance by predatory and scavenger taxa alongside an increased abundance of 

juveniles.

Due to the distance of beaches from deepwater blowouts and the combination of weathering and 

dispersant treatment of the oil offshore, the toxicity and quantity of the oil reaching shore should be 

greatly reduced, thereby minimizing the chances of irreversible damage to the impacted areas. A blowout 

in shallower waters near shore may have equal or greater impacts because of a shorter period of 

weathering and dispersion prior to shoreline contact, even though a smaller volume of spilled oil would 

be expected.

Vessel traffic in close proximity to barrier islands has been shown to move considerably more bottom 

sediment than tidal currents, thus increasing coastal and barrier island erosion rates. If staging areas for 

cleanup of a catastrophic spill are in close proximity to these islands, recovery time of the barrier islands 

could be greatly extended because of the large number of response vessels.

Phase 4—Post-Spill, Long-Term Recovery and Response

Oil or its components that remain in the sand after cleanup may be (1) released periodically when 

storms and high tides resuspend or flush beach sediments, (2) decomposed by biological activity, or 

(3) volatilized and dispersed. While it is assumed that the majority of spilled oil would be dissipated 

offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil has the 

potential to persist in the environment long after a spill event. For example on sandy beaches, oil can sink 

deep into the sediments. As stranded oil weathers, some oil may become buried through natural beach 

processes and appear as surface residual balls (SRB’s; <10 cm [4 in]) or as surface residual patties 

(SRP’s; 10 cm to 1 m [4 in to 3 ft]) (Table B-4). Such balls continue to provide a source of 

contamination with accompanying toxic effects.

The cleanup impacts of a catastrophic spill could result in short-term (up to 2 years) adjustments in 

beach profiles and configurations as a result of sand removal and disturbance during cleanup operations. 

Some oil contact to lower areas of sand dunes is expected. This contact would not result in significant 

destabilization of the dunes. The long-term stressors to barrier beach communities caused by the physical 

effects and chemical toxicity of an oil spill may lead to decreased primary production, plant dieback, and 

hence, further erosion (Ko and Day, 2004).

The protection once afforded to inland marshes by coastal barrier beaches has been greatly reduced 

because of decreased elevations and the continued effect of subsidence, sea-level rise, and saltwater 

intrusion. A catastrophic spill has the potential to contribute to this reduction through increased erosion 

as a result of plant dieback and cleanup efforts.

Overall Summary and Conclusion (Phases 1-4)

As a result of a catastrophic spill, many of the barrier islands and beaches would receive varying 

degrees of oiling. However, most areas of oiling are expected to be lightly oiled, and sand removal 

during cleanup activities should be minimal. The long-term stressors to barrier beach communities 
B-24 Central Planning Area Lease Sales 235, 241, and 247 EIS

caused by the physical effects and chemical toxicity of an oil spill may lead to decreased primary 

production, plant dieback, and hence, further erosion.

B.3.1.4. Wetlands

Phase 1—Initial Event

There would likely be no adverse impacts to wetlands as a result of the events and the potential 

impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event because these 

resources would not be contacted until the oil reached the shoreline.

Phase 2—Offshore Spill

There would likely be no adverse impacts to wetlands as a result of the events and the potential 

impact-producing factors that could occur throughout Phase 2 of a catastrophic spill event because these 

resources would not be contacted until the oil reached the shoreline.

Phase 3—Onshore Contact

Coastal wetland habitats in the Gulf of Mexico occur as bands around waterways; broad expanses of 

saline, brackish, and freshwater marshes; mud and sand flats; and forested wetlands of cypress-tupelo 

swamps and bottomland hardwoods. Offshore oil spills would have a low probability of contacting and 

damaging any wetlands along the Gulf Coast, except in the case of a catastrophic event. This is because 

of the distance of the spill to the coast, the likely weathered condition of oil (through evaporation, 

dilution, and biodegradation) should it reach the coast, and because wetlands are generally protected by 

barrier islands, peninsulas, sand spits, and offshore currents.

While a catastrophic spill from a shallow-water blowout is expected to be lower in volume than a 

deepwater blowout, a potential shallow-water site could be closer to shore, allowing less time for oil to be 

weathered, dispersed, and recovered before it impacted coastal resources. A spill from a catastrophic 

blowout could oil a few to several hundred acres of wetlands depending on the depth of inland penetration 

(Burdeau and Collins, 2010). This would vary from moderate to heavy oiling. Further detail on this 

catastrophic OSRA run is contained in Appendix C. 

The NOAA Environmental Sensitivity Index (ESI) ranks shorelines according to their sensitivity to 

oil, the natural persistence of oil, and the expected ease of cleanup after an oil spill. These factors cause 

oil to persist in coastal and estuarine areas (USDOI, MMS, 2010). According to the ESI, the most 

sensitive shoreline types (i.e., sheltered tidal flats, vegetated low banks, salt/brackish-water marshes, 

freshwater marshes/swamps, and scrub-shrub wetlands) tend to accumulate oil and are difficult to clean, 

thus causing oil to persist in these coastal and estuarine areas (USDOI, MMS, 2010).

In the case of catastrophic spills in the GOM, preemptive oil-response strategies would be initiated 

and include the deployment of oil booms, skimmer ships, and barge barriers to protect the beaches and 

adjacent wetlands. Boom deployment must also include plans for monitoring and maintaining the 

protective boom systems to assure that these systems are installed and functioning properly and that they 

are not damaging the wetlands they are trying to protect. In most cases, the beach face would take the 

most oil; however, in areas where the marsh is immediately adjacent to the beach face or embayments, or 

in the case of small to severe storms, marshes would be oiled. For example, in Alabama, Mississippi, and 

Florida, severe weather could push oil into the tidal pools and back beach areas that support tidal marsh 

vegetation.

The primary factors that affect vegetation responses to oil are toxicity of the oil and extent of plant 

coverage, amount of contact with and penetration of the soil, plant species affected, oiling frequency, 

season, and cleanup activities (Mendelssohn et al., 2012). Previous studies of other large spills have 

shown that, when oil has a short residence time in the marsh and it is not incorporated into the sediments, 

the marsh vegetation has a high probability of survival, even though aboveground die-off of marsh 

vegetation may occur (Lin et al., 2002). However, if re-oiling occurs after the new shoots from an initial 

oiling are produced, such that the new shoots are killed, then the marsh plants may not have enough 

stored energy to produce a second round of new shoots. Other studies noted the utilization of dispersants

in the proper dosages results in a reduction in marsh damage from oiling (Lin and Mendelssohn, 2009). 

The works of several investigators (Webb et al., 1981 and 1985; Alexander and Webb, 1983 and 1987; 
Catastrophic Spill Event Analysis B-25

Lytle, 1975; Delaune et al., 1979; Fischel et al., 1989) evaluated the effects of potential spills to area 

wetlands. For wetlands along the central Louisiana coast, the critical oil concentration is assumed to be 

0.025 gallons per ft2 (1.0 liter per m2

) of marsh. Concentrations less than this may cause diebacks for one 

growing season or less, depending upon the concentration and the season during which contact occurs. 

The duration and magnitude of a spill resulting from a catastrophic blowout could result in concentrations 

above this critical level and would result in longer term effects to wetland vegetation, including some 

plant mortality and loss of land.

Due to the distance of deep water from shore, the possibility of a spill from a deepwater blowout

reaching coastal wetlands with the toxicity to significantly impact the coastal wetlands is low because of 

the response procedures implemented during a catastrophic spill. (It is assumed that oil would reach 

shore within 2-4 weeks.) Therefore, a spill from a shallow-water blowout is more likely to contribute to 

wetland damage. However, for the few deepwater areas that are located closer to shore, such as in the 

Mississippi Canyon Area, the amount of time before shoreline contact could occur could be estimated to 

be the same as the estimate given for the shallow-water scenario, i.e., 1-3 weeks.

Offshore skimming, burning, and dispersal treatments for the oil near the spill site would result in 

capture, detoxification, and dilution of the majority of oil spilled. The utilization of nearshore booming 

protection for beaches and wetlands could also help to reduce oiling of these resources, if done correctly. 

Booms deployed adjacent to marsh shorelines can be lifted by wave action onto marsh vegetation, 

resulting in plant mortality under the displaced booms. The activity of oil cleanup can result in additional 

impacts on wetlands if not done properly. During the Deepwater Horizon explosion, oil spill, and 

response, aggressive onshore and marsh cleanup methods (such as the removal by mechanized equipment, 

in-situ burning, etc.) were not extensively utilized. The severity of oiling is the main factor that dictates 

the appropriate marsh cleanup method to be utilized (refer to Table B-4). 

Phase 4—Post-Spill, Long-Term Recovery and Response

Wetlands serve a number of important ecological functions. For example, Louisiana’s coastal 

wetlands support more than two-thirds of the wintering waterfowl population of the Mississippi Flyway 

(Louisiana Department of Wildlife and Fisheries, 2012). Therefore, loss of wetlands would also impact a 

significant portion of the waterfowl population. Another important ecological function of wetlands is 

their use as a nursery for estuarine-dependent species of fish and shellfish. Wetland loss would reduce the 

available nursery habitat.

The duration and magnitude of a spill resulting from a catastrophic blowout could result in high 

concentrations of oil that would result in long-term effects to wetland vegetation, including some plant 

mortality and loss of land. Silliman et al. (2012) found that after the Macondo well blowout and spill, oil 

coverage of Louisiana salt marshes was primarily concentrated on their seaward edges. Oil-driven plant 

death on the edges of these marshes more than doubled the rates of shoreline erosion, further driving 

marsh platform loss that is likely to be permanent. Eighteen months after the Macondo well blowout and 

spill, in previously oiled, noneroded areas, marsh grasses had largely recovered, and the elevated 

shoreline retreat rates observed at oiled sites had decreased to levels at reference marsh sites. Studies of 

impacted wetlands have demonstrated that wetlands can recover from the impacts of oil spills, but the 

recovery process varies from extremely slow in mangrove swamps (Burns et al., 1993 and 1994) to 

relatively rapid in grass-dominated marshes subject to in-situ burning of oil (Baustian et al., 2010).

Land loss caused by the oiling of wetlands would add to continuing impacts of other factors, such as 

hurricanes, subsidence, saltwater intrusion, and sea-level rise. The wetlands along the Gulf Coast have 

already been severely damaged by the 2005 and 2008 hurricane seasons, leaving the mainland less 

protected. It was estimated in 2000 that coastal Louisiana would continue to lose land at a rate of 

approximately 2,672 hectares/year (10 mi2

/year) over the next 50 years. Further, it was estimated that an 

additional net loss of 132,794 hectares (512 mi2

) may occur by 2050, which is almost 10 percent of 

Louisiana’s remaining coastal wetlands (Barras et al., 2003). Barras (2006) indicated an additional 

562 km2 (217 mi2

) of land lost during the 2005 hurricane season. A catastrophic spill occurring nearshore 

would contribute further to this landloss. Following Hurricanes Katrina and Rita, another series of 

hurricanes (Gustav and Ike) made landfall along the Louisiana and Texas coasts in September 2008. 

Hurricane Gustav made landfall as a Category 2 storm near Cocodrie, Louisiana, pushing large surges of 

saline water into the fresh marshes and coastal swamps of Louisiana from Grand Isle westward. While 

Hurricane Gustav did not impact the quantity of wetlands that Hurricanes Katrina and Rita impacted, it 
B-26 Central Planning Area Lease Sales 235, 241, and 247 EIS

did have a severe and continuing effect on the coastal barrier islands and the wetlands associated with 

backshore (back of the island) and foreshore (front of the island). While Hurricane Gustav affected the 

eastern portion of the Louisiana coast closer to Grand Isle and Houma, Hurricane Ike concentrated on 

Louisiana’s western coast. The Texas coast received the brunt of Hurricane Ike where it made landfall 

slightly east of Galveston. The storm surge heavily eroded the dune systems and significantly lowered 

the beach elevations along the eastern portion of the Texas coast near Galveston and the Bolivar 

Peninsula. The erosion and wash-over associated with Hurricane Ike’s tidal surge breeched beach ridges 

and opened the inland freshwater ponds and their associated wetlands to the sea. As a result of the four 

successive storms, the Louisiana and Texas coasts have lost protective elevations, barrier islands, and 

wetlands, and they now have the potential for transitioning to a less productive salt-marsh system in areas 

where fresh-marsh systems once existed. In addition, the loss of these protective elevations has increased 

the vulnerability of coastal wetlands to catastrophic oil-spill events.

A poorly executed oil cleanup can result in additional impacts. Aggressive onshore and marsh 

cleanup methods (such as removal by mechanized equipment, in-situ burning, marsh cutting, and foot 

entry into the marsh for manual removal) probably would not be initiated until the oil spill has been 

stopped. Depending on the marsh remediation methods used, further impacts to the wetlands may occur 

from cleanup activities. Boat traffic in marsh areas from the thousands of response vessels associated 

with a catastrophic spill would produce an incremental increase in erosion rates, sediment resuspension, 

and turbidity (i.e., an adverse but not significant impact to coastal wetland and seagrass habitats). 

Overall Summary and Conclusion (Phases 1-4)

A spill from a catastrophic blowout could oil a few to several hundred acres of wetlands depending on 

the depth of inland penetration (Burdeau and Collins, 2010). This would vary from moderate to heavy 

oiling. Impacts to wetlands would vary according to the severity of the oiling. The duration and 

magnitude of the spill could result in severe oiling of wetlands in some areas, causing long-term effects to 

wetland vegetation, including some plant mortality and loss of land. 

B.3.1.5. Seagrass Communities

Phase 1—Initial Event

There would likely be no adverse impacts to submerged vegetation as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event 

because of the likely distance from the spill event to the nearest submerged vegetation beds.

Phase 2—Offshore Spill

There would likely be no adverse impacts to submerged vegetation as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 2 of a catastrophic spill because of 

the likely distance from the spill event to the nearest submerged vegetation beds.

Phase 3—Onshore Contact

According to the most recent and comprehensive data available, approximately 500,000 hectares 

(1.25 million acres; 505,857 hectares) of submerged seagrass beds are estimated to exist in exposed, 

shallow coastal waters and embayments of the northern Gulf of Mexico, and over 80 percent of this area 

is in Florida Bay and Florida coastal waters (calculated from Handley et al., 2007). Submerged 

vegetation distribution and composition depend on an interrelationship among a number of environmental 

factors that include water temperature, depth, turbidity, salinity, turbulence, and substrate suitability 

(Kemp, 1989; Onuf, 1996; Short et al., 2001). Marine seagrass beds generally occur in shallow, relatively 

clear, protected waters with predominantly sand bottoms (Short et al., 2001). Freshwater submerged 

aquatic vegetation (SAV) species occur in the low-salinity waters of coastal estuaries (Castellanos and 

Rozas, 2001). Seagrasses and freshwater SAV’s provide important nursery and permanent habitat for 

sunfish, killifish, immature shrimp, crabs, drum, trout, flounder, and several other nekton species, and 

they provide a food source for species of wintering waterfowl and megaherbivores (Rozas and Odum, 
Catastrophic Spill Event Analysis B-27

1988; Rooker et al., 1998; Castellanos and Rozas, 2001; Heck et al., 2003; Orth et al., 2006). Further 

detail on this catastrophic OSRA run is contained in Appendix C. 

If oil comes into areas with submerged beds, increased water turbulence from waves, storms, or 

vessel traffic could break apart the surface oil sheen and disperse some oil into the water column or mix 

oil with sediments that would settle and coat an entire plant. Coating of the plat from the oil and sediment 

mixture would cause reduced chlorophyll production and could lead to a decrease in vegetation (Teal and 

Howarth, 1984; Burns et al., 1994; Erftemeijer and Lewis, 2006). This coating situation also happens 

when oil is treated with dispersants because the dispersants break down the oil and it sinks into the water 

column (Thorhaug et al., 1986; Runcie et al., 2004). However, as reviewed in Runcie et al. (2004), oil 

mixed with dispersants has shown an array of effects on seagrass depending on the species and dispersant 

used. With a greater distance from shore, there is a greater chance of the oil being weathered by natural 

and mechanical processes by the time it reaches the nearshore habitat.

Depending on the species and environmental factors (e.g., temperature and wave action), seagrasses 

may exhibit minimal impacts, such as localized loss of pigmentation, from a spill; however, communities 

residing within the beds could accrue greater negative outcomes (den Hartog and Jacobs, 1980; Jackson 

et al., 1989; Kenworthy et al., 1993; Taylor et al., 2006). Community effects could range from either 

direct mortality due to smothering or indirect mortality from loss of food sources and habitat to a decrease 

in ecological performance of the entire system depending on the severity and duration of the spill event 

(Zieman et al., 1984).

Prevention and cleanup efforts could also affect the health of submerged vegetation communities 

(Zieman et al., 1984). Many physical prevention methods such as booms, barrier berms, and diversions 

can alter hydrology, specifically changing salinity and water clarity. These changes would harm certain 

species of submerged vegetation because they are tolerant to specific salinities and light levels (Zieman 

et al., 1984; Kenworthy and Fonesca, 1996; Frazer et al., 2006). With cleanup, there is increased boat and 

human traffic in these sensitive areas that generally are protected from this degree of human disturbance 

prior to the response. Increased vessel traffic would lead to elevated water turbidity and increased 

propeller scarring. While the elevated levels of water turbidity from vessels would be short-term and the 

possible damages from propellers could be longer, both events would be localized during the prevention 

and cleanup efforts (Zieman, 1976; Dawes et al., 1997).

Phase 4—Post-Spill, Long-Term Recovery and Response

According to the most recent and comprehensive data available, approximately 500,000 hectares 

(1.25 million acres; 505,857 hectares) of submerged seagrass beds are estimated to exist in exposed, 

shallow coastal waters and embayments of the northern Gulf of Mexico, and over 80 percent of this area 

is in Florida Bay and Florida coastal waters (calculated from Handley et al., 2007). Submerged 

vegetation distribution and composition depend on an interrelationship among a number of environmental 

factors that include water temperature, depth, turbidity, salinity, turbulence, and substrate suitability 

(Kemp, 1989; Onuf, 1996; Short et al., 2001). Seagrasses and freshwater SAV’s provide important 

nursery and permanent habitat for sunfish, killifish, immature shrimp, crabs, drum, trout, flounder, and 

several other nekton species, and they provide a food source for species of wintering waterfowl and 

megaherbivores (Rozas and Odum, 1988; Rooker et al., 1998; Castellanos and Rozas, 2001; Heck et al., 

2003; Orth et al., 2006).

A source of potential long-term impacts to submerged beds from a catastrophic spill event is the 

possibility of buried or sequestered oil becoming resuspended after a disturbance, which would have 

similar effects as the original oiling event. This could occur in the event of hurricane impacts, which 

exacerbate the problem with numerous other short-terms stresses, such as turbidity, abrasion, breakage, 

uprooting SAV and seagrasses, and the alteration of bottom profiles and hydrology. Because different 

species have different levels of sensitivity to oil, it is difficult to compare studies and extrapolate what 

variables caused the documented differences in vegetation and community health (Thorhaug et al., 1986; 

Runcie et al., 2004). In general, studied seagrasses did not show significant negative effects from an oil 

spill (den Hartog and Jacobs, 1980; Kenworthy et al., 1993; Taylor et al., 2006; Taylor et al., 2007).

If bays and estuaries accrue oil, there is an assumption that there would be a decrease in seagrass 

cover and negative community impacts. Submerged vegetation serves important ecological functions. 

For example, seagrasses and freshwater SAV’s provide important habitat and are a food source for a wide 

range of species in multiple life history stages (Castellanos and Rozas, 2001; Short and Coles, 2001; 
B-28 Central Planning Area Lease Sales 235, 241, and 247 EIS

Caldwell, 2003). Therefore, loss of submerged vegetation would adversely impact these species with a 

loss of valuable habitat and food.

Overall Summary and Conclusion (Phases 1-4)

Because of the likely distance of an initial catastrophic spill event to submerged vegetation

communities, there would be no adverse impacts to submerged vegetation resulting from the initial event 

(Phase 1). Also, with regards to an offshore spill event, there would likely be no adverse impacts to 

submerged vegetation before the spill reaches shore (Phase 2). An estimated probability of oil contacting 

its coastline from the CPA example OSRA run can be found in Appendix C (Phase 3). It is assumed 

when these coastlines are contacted with oil, all associated habitat are considered oiled. If oil comes into 

areas with submerged beds, oil mixed with sediments or with dispersants could settle and coat an entire 

plant and could cause reduced chlorophyll production and could lead to a decrease in vegetation. 

Depending on the species and environmental factors (e.g., temperature and wave action), seagrasses may 

exhibit minimal impacts, such as localized loss of pigmentation, from an oil spill; however, communities 

residing within the beds could accrue greater negative outcomes. Increased vessel traffic from cleanup 

efforts would lead to elevated water turbidity and increased propeller scarring. A source of potential 

long-term impacts to submerged beds from a catastrophic spill event is the possibility of buried or 

sequestered oil becoming resuspended after a disturbance, which would have similar effects as the 

original oiling event (Phase 4). While there are impacts on submerged vegetation from an oiling event, 

the probabilities of an event to occur and contact coastlines are generally low and any impacts that can 

occur depend on a variety of factors (e.g., plant species, oil type, current environmental conditions, etc.). 

In general, studied seagrasses did not show significant negative effects from a spill (den Hartog and 

Jacobs, 1980; Kenworthy et al., 1993; Taylor et al., 2006 and 2007).

B.3.1.6. Live Bottoms (Pinnacle Trend and Low Relief) 

The Gulf of Mexico has hard-bottom features upon which encrusting and epibenthic organisms attach 

on the continental shelf in water depths less than 300 m (984 ft). Live bottom features occur in the 

northeastern portion of the CPA and in the EPA. The Pinnacle Trend is located in the northeastern 

portion of the central Gulf of Mexico at the outer edge of the Mississippi-Alabama shelf between the 

Mississippi River and De Soto Canyon. Live bottom (Pinnacle Trend) features are defined in NTL 

2009-G39 as “small, isolated, low to moderate relief carbonate reefal features or outcrops of unknown 

origin or hard substrates exposed by erosion that provide area for the growth of sessile invertebrates and 

attract large numbers of fish.” Fish are attracted to outcrops that provide hard substrate for sessile 

invertebrates to attach. BOEM does not allow bottom-disturbing activities to occur within 30 m (98 ft) of 

any hard bottoms/pinnacles in 74 lease blocks in the CPA (each block is typically 3 mi x 3 mi).

Live bottom (low relief) features are defined in NTL 2009-G39 as “seagrass communities; areas that 

contain biological assemblages consisting of sessile invertebrates living upon and attached to naturally 

occurring hard or rocky formations with rough, broken, or smooth topography; and areas where hard 

substrate and vertical relief may favor the accumulation of turtles, fishes, or other fauna”. These features 

also include the reef communities like those found on the Florida Escarpment. BOEM has stipulations to 

protect these features from impacts, including bottom-disturbing activity. This chapter discusses the hard 

substrate, as seagrasses are covered in Chapter B.3.1.5. 

Phase 1—Initial Event

A blowout from an oil well could result in a catastrophic spill event. A catastrophic blowout would 

result in released oil rapidly rising to the sea surface because all known reserves in the GOM have 

specific gravity characteristics that would preclude oil from sinking immediately after release at a 

blowout site. The oil would surface almost directly over the source location. However, if the oil is 

ejected under high pressure, micro-droplets of oil may form and become entrained in the water column 

(Boehm and Fiest, 1982; Adcroft et al., 2010). The upward movement of the oil may be reduced if 

methane mixed with the oil is dissolved into the water column, reducing the oil’s buoyancy (Adcroft 

et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by vigorous 

turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the water column, 
Catastrophic Spill Event Analysis B-29

creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). Dispersed oil in the water 

column begins to biodegrade and may flocculate with particulate matter, promoting sinking of the 

particles. Subsea plumes or sinking oil on particulates may contact live bottom features.

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. Some fine sediment could travel up to a few 

thousand meters before redeposition, negatively impacting a localized area of benthic communities. If a 

blowout were to occur close enough to a live bottom feature, suspended sediment may impact the 

organisms living on the feature.

A catastrophic blowout that occurs above the seabed (at the rig, along the riser between the seafloor 

and sea surface, or through leak paths on the BOP/wellhead) would not disturb the sediment.

The use of subsea dispersants would increase the exposure of offshore benthic habitats to dispersed 

oil droplets in the water column, as well as the chemicals used in the dispersants. The use of subsea 

dispersants is not likely to occur for seafloor blowouts outside the well casing.

Impacts to Live Bottom Features

Impacts that occur to benthic organisms on live bottom features as a result of a blowout would depend 

on the type of blowout, distance from the blowout, relief of the biological feature, and surrounding 

physical characteristics of the environment (e.g., turbidity). The distancing of bottom-disturbing activities 

from Pinnacle and live bottom, low-relief features helps to prevent blowouts in the immediate vicinity of 

a live bottom feature or its associated biota. Much of the oil released from a blowout would rise to the sea 

surface, therefore minimizing the impact to benthic communities by direct oil exposure. However, small 

droplets of oil that are entrained in the water column for extended periods of time may migrate into areas 

that have live bottom features. Although these small oil droplets will not sink themselves, they may

attach to suspended particles in the water column and then be deposited on the seafloor (McAuliffe et al., 

1975). The resultant long-term impacts, such as reduced recruitment success, reduced growth, and 

reduced coral or other epibenthic cover, as a result of impaired recruitment, are discussed in Phase 4 

(“Post-Spill, Long-Term Recovery and Response”). Also, if the blowout were to occur beneath the 

seabed, suspension and subsequent deposition of disturbed sediment may smother localized areas of live 

bottom communities.

Following a catastrophic, subsurface blowout, benthic communities on a live bottoms exposed to 

large amounts of resuspended and then deposited sediments could be subject to sediment suffocation, 

exposure to resuspended toxic contaminants and to reduced light availability. Impacts to fauna found on 

hard bottoms as a result of sedimentation would vary based on species, the height to which the organism 

grows, degree of sedimentation, length of exposure, burial depth, and the organism’s ability to clear the 

sediment. Impacts may range from sublethal effects (such as reduced or slower growth, alteration in 

form, and reduced recruitment and productivity) to suffocation and death (Rogers, 1990; Fucik et al., 

1980).

The initial blowout impact would be greatest to communities located in clear waters that experience 

heavy sedimentation. The most sensitive organisms are typically elevated above soft sediments, making 

them less likely to be buried, and it is unlikely that corals would experience heavy sedimentation because 

they are located within Live Bottom (Low Relief) Stipulation blocks that distance bottom-disturbing 

activity from the features. None of the Live Bottom Stipulation blocks were included in the current 

proposed lease sale, farther distancing oil and gas activity from live bottoms. In addition, BOEM 

conducts case-by-case reviews of plans submitted by operators to ensure that the proposed activity will 

not impact sensitive seafloor features. It is possible, however, for some live bottoms to experience some 

turbidity or sedimentation impacts from a blowout if they are downstream of a current transporting 

sediment. Corals may experience discoloration or bleaching as a result of sediment exposure, although 

recovery from such exposure may occur within 1 month (Wesseling et al., 1999).

Initial impacts would be much less extreme in a turbid environment (Rogers, 1990). For example, the 

Pinnacle Trend community exists in a relatively turbid environment, starting just 65 km (37 mi) east of 

the mouth of the Mississippi River and trending to the northeast, and many low-relief live bottoms are 

frequently covered with a thin sand veneer that moves with waves and bottom currents, exposing and 

covering up areas with movement (Phillips et al., 1990; Gittings et al., 1992). Sediment from a blowout, 

if it occurred nearby, may have a reduced impact on these communities compared with an open-water reef 
B-30 Central Planning Area Lease Sales 235, 241, and 247 EIS

community, as these organisms are more tolerant of suspended sediment (Gittings et al., 1992). Many of 

the organisms that predominate in this community also grow tall enough to withstand the sedimentation 

that results from their turbid environment or have flexible structures that enable the passive removal of 

sediments (Gittings et al., 1992). Those organisms that have a lesser relief could experience 

sedimentation, abrasion, and suffocation. However, many organisms present in the lower relief, live 

bottom habitat are motile, can burrow in the sediment, or have mechanisms for dealing with turbidity and 

can be tolerant of short-term high turbidity events. For example, bivalves can reduce their filtration rates 

if the suspended sediment concentrations become elevated and can reject excess sediment through 

pseudofeces (Clarke and Wilber, 2000). Many crustaceans are able to tolerate high levels of suspended 

sediment; for example, crabs and shrimp spend a portion of their lives in estuaries and nearshore waters 

that are turbid (Wilber et al., 2005). These organisms are also able to move away from turbid areas that 

have sediment concentrations that become too high (Clarke and Wilber, 2000; Wilber et al., 2005). 

Oysters, on the other hand, are not able to move away from turbidity, but they are tolerant of this 

environmental factor as they tend to live near the mouths of rivers that deposit sediment into their habitat 

(Wilber et al., 2005). Many of these organisms can also rapidly repopulate an area affected by 

sedimentation (Fucik et al., 1980).

A portion or the entire rig may sink to the seafloor as a result of a blowout. The benthic features and 

communities upon which the rig settles would be destroyed or smothered. Encrusting organisms would 

be crushed by a rig if it lands on a live bottom feature. A settling rig may suspend sediments, which may 

smother nearby benthic communities if the sediment is redeposited on sensitive features. The habitats 

beneath the rig may be permanently lost; however, the rig itself may become an artificial reef upon which 

epibenthic organisms may settle. The surrounding benthic communities that were smothered by sediment 

would repopulate from nearby stocks through spawning recruitment and immigration if the hard substrate 

upon which they live was not physically destroyed. Destruction of a live bottom community by a sinking 

rig is highly unlikely because BOEM requires infrastructure to be distanced from live bottoms.

Phase 2—Offshore Spill

A spill from a shallow-water blowout could impact benthic communities on the continental shelf 

because of the blowout’s proximity to these habitats. The scenario (Table B-4) for a catastrophic spill on 

the continental shelf is assumed to last 2-5 months and to release 30,000 bbl per day. A total volume of 

0.9-3.0 MMbbl of South Louisiana midrange paraffinic sweet crude oil could be released, which will float 

(APIo >10). An anticipated 35,000 bbl of dispersant may be applied to the surface waters.

A spill from a deepwater blowout could also impact shelf communities if surface oil is transported to 

these areas. The scenario (Table B-4) for a catastrophic spill in deep water is assumed to last 4-6 months 

and to release 30,000-60,000 bbl per day. A total volume of 2.7-7.2 MMbbl of South Louisiana midrange 

paraffinic sweet crude oil will be released, which will float (APIo >10). Oil properties may change as it 

passes up the well and through the water column, and it may become emulsified. An anticipated 

33,000 bbl of dispersant may be applied to the surface waters and 16,500 bbl may be applied subsea. 

Weathering and dilution of the oil will also occur as it travels from its release point. It is unlikely that a 

subsurface plume from a deepwater blowout would impact shelf communities. The oil is anticipated to 

remain in deep water and to be directed by water currents in the deep water. These currents do not 

typically transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 2008).

Impacts to Live Bottom Features

Impacts from Surface Oil

Sensitive live bottom communities can flourish on hard bottoms in the Gulf of Mexico. The eastern 

Gulf of Mexico contains scattered, low-relief live bottoms, including areas of flat limestone shelf rock 

and the Pinnacle Trend area, located on the Mississippi Alabama continental shelf, which includes lowand high-relief features that are 60-120 m (197-394 ft) below the sea surface. The depth at which 

Pinnacles and most live bottom, low-relief features flourish below the sea surface helps to protect these 

habitats from a surface oil spill. Rough seas may mix the oil into subsurface water layers, where it may 

impact sessile biota. The longer the seas are rough, the greater the amount of oil from a surface slick 

would be mixed into the water column. Measurable amounts of oil have been documented to mix from 

the surface down to a 10-m (33-ft) depth, although modeling exercises have indicated such oil may reach 
Catastrophic Spill Event Analysis B-31

a depth of 20 m (66 ft). At this depth, however, the oil is found at concentrations several orders of 

magnitude lower than the amount shown to have an effect on corals and other benthic organisms (Lange, 

1985; McAuliffe et al., 1975 and 1981; Knap et al., 1985; Scarlett et al., 2005; Hemmer et al., 2010; 

George-Ares and Clark, 2000). Low-relief, live bottom habitats located in shallow coastal water may be 

at greater risk of surface oil mixing to the depth where their active growth occurs; however, because oil 

and gas activities currently take place far from the coastlines where nearshore live bottoms are located, 

the surface oil will be well dispersed and diluted by the time it reaches waters above the shallow live 

bottoms. Further detail on this catastrophic OSRA run is contained in Appendix C. 

Impacts from Subsurface Oil

The presence of a subsurface oil plume on the continental shelf from a shallow-water blowout may 

affect benthic communities on live bottom features. A majority of oil released is expected to rise rapidly 

to the sea surface above the release point because of the specific gravity characteristics of the oil reserves 

in the GOM, thus not impacting sensitive benthic communities. If oil is ejected under high pressure, oil 

droplets may become entrained in the water column (Boehm and Fiest, 1982; Adcroft et al., 2010). The 

upward movement of the oil may be reduced if methane mixed with the oil is dissolved into the water 

column, reducing the oil’s buoyancy (Adcroft et al., 2010). Large oil droplets would rise to the sea 

surface, but smaller droplets, formed by vigorous turbulence in the plume or the injection of dispersants, 

may remain neutrally buoyant in the water column, creating a subsurface plume (Adcroft et al., 2010; 

Joint Analysis Group, 2010). Dispersed oil in the water column begins to biodegrade and may flocculate 

with particulate matter, promoting sinking of the particles. Subsurface plumes generated by high-pressure 

dissolution of oil may come in contact with live bottom habitats. A sustained spill would continuously 

create surface slicks and possibly subsurface spill plumes. Some of the oil in the water column will 

become diluted or evaporated over time, reducing any localized transport to the seafloor (Vandermeulen, 

1982). In addition, microbial degradation of the oil occurs in the water column so that the oil would be 

less toxic as it travels from the source (Hazen et al., 2010). However, a sustained spill may result in 

elevated exposure concentrations to benthic communities if the plume reaches them. The longer the spill 

takes to stop, the longer the exposure time and the higher the exposure concentration may be.

Live bottom, low-relief features have a greater chance of being impacted by subsea plumes than some 

Pinnacle features because currents may sweep around the larger features, as they do with topographic 

features (Rezak et al., 1983; McGrail, 1982). The lower relief live bottoms (including low-relief features 

in the Pinnacle Trend) may fall in the path of the plume because the feature is not large enough to divert a 

current. Low-level exposures of organisms to oil from a subsea plume may result in chronic or temporary 

impacts. For example, feeding activity or reproductive ability may be reduced when coral is exposed to 

low levels of oil; however, impacts may be temporary or unable to be measured over time. Experiments 

indicated that oil exposure reduced the normal feeding activity of coral, and oiled reefs produced smaller 

gonads than unoiled reefs, resulting in reproductive stress (Lewis, 1971; Guzmán and Holst, 1993). In 

addition, photosynthesis and growth may be reduced with oil exposure, and petroleum may be 

incorporated into coral tissue (Cook and Knap, 1983; Dodge et al., 1984; Burns and Knap, 1989; Knap 

et al., 1982; Kennedy et al., 1992). Sublethal responses of other marine invertebrates on live bottoms may 

result in population level changes (Suchanek, 1993) at concentrations as low as 1-10 ppb (Hyland and 

Schneider, 1976). Sublethal impacts may include reduced feeding rates, reduced ability to detect food, 

erratic movement, ciliary inhibition, tentacle retraction, reduced movement, decreased aggression, and 

altered respiration (Scarlett et al., 2005; Suchanek, 1993). Embryonic life stages of benthic organisms 

may experience toxic effects at lower levels than adult stages (Fucik et al., 1995; Suchanek, 1993; Beiras 

and Saco-Álvarez, 2006; Byrne, 1989). 

It is unlikely that a subsurface plume from a deepwater blowout would impact live bottom shelf 

communities. The oil is anticipated to remain in deep water and be directed by water currents in the deep 

water. These currents do not typically transit from deep water up onto the shelf (Pond and Pickard, 1983; 

Inoue et al., 2008).

Impacts from Dispersed Oil

If dispersants are used at the sea surface, oil may mix into the water column. If applied subsea, they 

can travel with currents through the water, and they may contact or settle on sensitive features. Note that, 
B-32 Central Planning Area Lease Sales 235, 241, and 247 EIS

as indicated above, a deepwater plume would not travel onto the continental shelf, but a plume formed on 

the continental shelf could impact live bottom features. If near the source, the dispersed oil could be 

concentrated enough to harm the community. If the oil remains suspended for a longer period of time, it 

would be more dispersed and present at lower concentrations. Reports on dispersant usage on surface oil 

indicate that a majority of the dispersed oil remains in the top 10 m (33 ft) of the water column, with 

60 percent of the oil in the top 2 m (6 ft) (McAuliffe et al., 1981). Dispersant usage also reduces the oil’s 

ability to stick to particles in the water column, minimizing oil adhering to sediments and traveling to the 

seafloor (McAuliffe et al., 1981). There is very little information on the mixing and dispersion of subsea 

dispersants.

Dispersed oil reaching live bottoms in the Gulf of Mexico would be expected to occur at very low 

concentrations (<1 part per million [ppm]) (McAuliffe et al., 1981). Such concentrations would not be 

life threatening to larval or adult stages at this depth below the sea surface based on experiments 

conducted with benthic organisms. Any dispersed oil in the water column that comes in contact with live 

bottoms may evoke short-term negative responses by the organisms (Wyers et al., 1986; Cook and Knap, 

1983; Dodge et al., 1984; Scarlett et al., 2005; Renzoni, 1973).

The impact of dispersants on benthic organisms is dependent on the dispersant used, length of 

exposure, and the physical barriers the organism has to protect itself from the dispersant. Organisms with 

shells appear to be more tolerant of dispersants than those with only a tissue barrier (Scarlett et al., 2005). 

In addition, organisms that produce mucus, such as coral, have an elevated tolerance for oil exposure 

(Mitchell and Chet, 1975; Ducklow and Mitchell, 1979). Concentrations of 100 ppm and 1,000 ppm oil 

plus dispersant in a ratio of 4:1 were necessary for oyster and mussel fertilization and development to 

become reduced when the larvae was exposed to the mixture (Renzoni, 1973). After 48 hours of 

exposure to dispersants, the blue mussel (Mytilus edulis) died at dispersant concentrations of 250 ppm, 

although reduced feeding rates were observed at 50 ppm (Scarlett et al., 2005). The snakelocks anemone 

(Anemonia viridis), which does not have a protective shell, was much more sensitive to dispersants. It 

retracted its tentacles and failed to respond to stimuli after 48 hours of exposure to 40 ppm dispersant 

(Scarlett et al., 2005). Corals exposed to dispersed oil showed mesenterial filament extrusion, extreme 

tissue contraction, tentacle retraction, localized tissue rupture, and reduced photosynthesis (Wyers et al., 

1986; Cook and Knap, 1983). Respiratory damage to organisms does not appear to be reversible; 

however, if the exposure is short enough, nervous system damage may be reversed and organisms may 

recover (Scarlett et al., 2005). Experiments using both anemones and corals showed recovery after 

exposure to dispersants (Scarlett et al., 2005; Wyers et al., 1986)

Concentrations used in historical experiments are generally much higher than the exposure that would 

occur in the field (Renzoni, 1973; George-Ares and Clark, 2000). Although historical experiments seem 

to indicate that the toxicity of oil increases with the addition of the dispersant, the toxicity of the oil 

actually remains the same as it was when it was not dispersed, but exposure increases due to the dispersed 

components of the oil (George-Ares and Clark, 2000). However, the increase of oil into the water column 

with the addition of dispersants is temporary, as the dispersed oil is more easily diluted with the 

surrounding water and biodegraded by bacteria (George-Ares and Clark, 2000). Therefore, concentrated 

dispersants are not anticipated to reach live bottoms, and any impacts that do occur should be sublethal 

and temporary.

Impacts from Oil Adhering to Sediments

BOEM’s policy, described in NTL 2009-G39, prevents wells from being placed immediately adjacent 

to sensitive communities. In the event of a seafloor blowout, however, some oil could be carried to live 

bottoms as a result of oil droplets adhering to suspended particles in the water column. Oiled sediment 

that settles to the seafloor may affect organisms attached to hard-bottom substrates. Impacts may include 

reduced recruitment success, reduced growth, and reduced benthic cover as a result of impaired 

recruitment. Experiments have shown that the presence of oil on available substrate for larval coral 

settlement has inhibited larval metamorphosis and larval settlement in the area. Oil exposure also 

increased the number of deformed polyps after metamorphosis occurred (Kushmaro et al., 1997). In 

addition, exposure to oiled sediment has also been shown to reduce the growth rate of clams (Dow, 1975).

The majority of organisms exposed to sedimented oil, however, are anticipated to experience lowlevel concentrations because as oiled sediments settle to the seafloor they become widely dispersed. 

Many organisms on live bottoms will be able to protect themselves from low levels of oiled sediment that 
Catastrophic Spill Event Analysis B-33

may settle out of the water column. Organisms with shells will not experience direct contact with the oil, 

and mobile organisms will be able to move away from areas where oiled sediment has accumulated. 

Coral may also be able to protect itself from low concentrations of sedimented oil that settles from the 

water column through mucus that will not only act as a barrier to protect coral from the oil in the water 

column but which also been shown to aid in the removal of oiled sediment on coral surfaces (Bak and 

Elgershuizen, 1976). In addition, because many organisms in live bottom habitats are tolerant of turbidity 

and sedimentation, slight addition of sediment to the area should not impact survival.

Impacts from Oil-Spill Response Activity

Oil-spill-response activity may also impact sessile benthic features. Booms anchored to the seafloor 

are sometimes used to control the movement of oil at the water surface. Boom anchors can physically 

impact sessile benthic organisms, especially when booms are moved around by waves (Tokotch, 2010). 

Vessel anchorage and decontamination stations set up during response efforts may also break or kill live 

bottoms that have unmapped locations if anchors are set on the habitat. Injury to live bottom habitat as a 

result of anchor impact may result in long-lasting damage or failed recovery. Effort should be made to 

keep vessel anchorage areas as far from sensitive benthic features as possible to minimize impact.

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 

buried. Based on stipulations as described in NTL 2009-G39, a well should be far enough away from a 

Pinnacle feature to prevent extruded drilling muds from smothering sensitive benthic communities. 

However, if drilling muds were to travel far enough or high enough in the water column to contact a 

sensitive community, the fluid would smother the existing community. Burial may lead to the elimination 

of a live bottom community.

Phase 3—Onshore Contact

There would likely be no adverse impacts to live bottom features as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 3 of a catastrophic spill because the 

live bottom features are located offshore.

Phase 4—Post-Spill, Long-Term Recovery and Response

Live bottoms exposed to large amounts of resuspended sediments following a catastrophic, 

subsurface blowout could be subject to sediment suffocation, exposure to resuspended toxic 

contaminants, and reduced light penetration. The greatest impacts would occur to communities that exist 

in clear water with very low turbidity, such as the live bottoms off Florida. The consequences of a 

blowout near one of these features could be long lasting, although the occurrence of a blowout near such 

sensitive communities is unlikely because of stipulations described in NTL 2009-G39, which distances 

bottom-disturbing activity from live bottom features. In addition, BOEM conducts case-by-case reviews 

of submitted plans and pipelines so that sensitive seafloor habitat is avoided. Impacts to a community in 

more turbid waters, such as those on the Mississippi-Alabama Shelf, would be greatly reduced, as the 

species are tolerant of suspended sediments, and recovery would occur quicker. Recovery time from 

sediment exposure would depend on the amount of sediment an organism was exposed to, if an entire 

population was demolished, and the extent of the loss.

Impacts may also occur from low-level or long-term oil exposure. This type of exposure has the 

potential to impact live bottom communities, resulting in impaired health. Long-term impacts such as 

reduced recruitment success, reduced growth, and reduced organism cover as a result of impaired 

recruitment may occur. Recovery may be fairly rapid from brief, low-level exposures, but it could be 

much longer if acute concentrations of oil contact organisms. Recovery time would then depend on 

recruitment from outside populations that were not affected by oiling.

Overall Summary and Conclusion (Phases 1-4)

A catastrophic spill on the continental shelf would have a greater impact on live bottom features than 

a deepwater spill. Surface oil from a deepwater spill would be weathered and diluted by the time it 
B-34 Central Planning Area Lease Sales 235, 241, and 247 EIS

reaches the surface waters over live bottom features (if it ever reaches them), and it would be unlikely, 

except in shallow coastal waters, that it would mix to the depth of the live bottoms in concentrations that 

could cause toxicity. Subsea plumes formed in deep water would not travel onto the continental shelf 

because deep-sea currents do not travel up a slope.

A catastrophic blowout and spill on the continental shelf has a greater chance to impact live bottom

features. If a blowout on the continental shelf occurs close enough to sensitive features, the organisms 

may be smothered by settling sediment that is displaced by the blowout. The farther a feature is from the 

blowout, the lower its chance of being covered with settling sediment or sediment upon which oil 

adhered. The distancing of oil and gas activity from live bottom features helps to prevent heavy 

sedimentation, as well as features being crushed by a sinking rig.

In most cases, the impacts from oil would be sublethal. Surface oil is not expected to mix to the zone 

of active growth, and any oil components that do reach that depth would be at sublethal concentrations. 

Subsea plumes may contact the live bottom features; however, because currents tend to travel around 

instead of over large seafloor features, the Pinnacle features should be protected from subsea plumes, 

while lower relief live bottoms may be impacted. The current oil and gas activity in the GOM, however, 

is distanced from low-relief live bottoms because no live bottom, low-relief blocks have been leased with 

the current proposed lease sales. Overall impacts of dispersed oil would be similar to subsea plumes. 

Spill response activity may impact low-relief, live bottom features if they are unmarked on nautical charts 

and vessels anchor on the features, but it is doubtful that a vessel would anchor on a marked Pinnacle 

feature.

Overall, a catastrophic spill would have a fairly low probability of impacting live bottom features 

because the bottom-disturbing activities of oil and gas activities are distanced from live bottom features 

within the Live Bottom Stipulation blocks, as described in NTL 2009-G39, and because BOEM conducts 

a case-by-case review of all plans to ensure that activities do not impact these seafloor features. In 

addition, the Live Bottom Stipulation blocks have not been leased as part of these proposed lease sales, 

creating farther distance between oil and gas activities and live bottoms. Also, live bottom features are 

protected by the limited mixing depth of surface oil compared with the depth of the live bottom features, 

currents sweeping around larger features, and the weathering and dispersion of oil that would occur with 

distance from the source as it travels toward the features. Low-relief features could have impacts from a 

blowout as their relief would not divert currents. In addition, the locations of these features are not all 

known so accidental anchor impacts may result in breakage of the features and possibly destruction. 

These low-relief features, however, would be protected by the regulated distance of current oil and gas 

activities, which increases the chance of oil becoming well dispersed before it reaches the features.

B.3.1.7. Topographic Features

The Gulf of Mexico has a series of topographic features (banks or seamounts) on the continental shelf 

in water depths less than 300 m (984 ft). Topographic features are isolated areas of moderate to high 

relief that provide habitat for hard-bottom communities of high biomass and moderate diversity. These 

features support prolific algae, invertebrate, and fish communities, and they provide shelter and food for 

large numbers of commercially and recreationally important fish. There are 37 named topographic 

features in the Gulf of Mexico with specific BOEM protections, including the Flower Garden Banks. 

BOEM has created “No Activity Zones” around topographic features in order to protect these habitats 

from disruption by oil and gas activities. A “No Activity Zone” is a protective perimeter drawn around 

each feature that is associated with a specific isobath (depth contour) surrounding the feature in which 

structures, drilling rigs, pipelines, and anchoring are not allowed. These “No Activity Zones” are areas 

where activity is prohibited based on BOEM’s policy. NTL 2009-G39 recommends that drilling should

not occur within 152 m (500 ft) of a “No Activity Zone” of a topographic feature.

Potentially sensitive biological features (PSBF’s) are features that have moderate to high relief (8 ft 

[2 m] or higher), provide hard surface for sessile invertebrates, and attract fish, but they are not located 

within the “No Activity Zone” of topographic features. These features are frequently located near 

topographic features. No bottom-disturbing activities that may cause impact to these features are 

permitted.
Catastrophic Spill Event Analysis B-35

Phase 1—Initial Event

A blowout from an oil well could result in a catastrophic spill event. A catastrophic blowout would 

result in released oil rapidly rising to the sea surface because all known reserves in the GOM have 

specific gravity characteristics that would preclude oil from sinking immediately after release at a 

blowout site. The oil would surface almost directly over the source location. However, if the oil is 

ejected under high pressure, micro-droplets of oil may form and become entrained in the water column 

(Boehm and Fiest, 1982; Adcroft et al., 2010). The upward movement of the oil may be reduced if 

methane mixed with the oil is dissolved into the water column, reducing the oil’s buoyancy and slowing 

its rise to the surface (Adcroft et al., 2010). Large oil droplets would rise to the sea surface, but smaller 

droplets, formed by vigorous turbulence in the plume or the injection of dispersants, may remain neutrally 

buoyant in the water column, creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 

2010). Dispersed oil in the water column begins to biodegrade and may flocculate with particulate 

matter, promoting sinking of the particles. Subsea plumes or sinking oil on particulates may contact 

topographic features. 

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. Fine sediment could travel up to a few thousand 

meters before redeposition, negatively impacting a localized area of benthic communities. If a blowout 

were to occur near a topographic feature, suspended sediment may impact the organisms living on the 

lower levels of the topographic feature (since water currents flow around the banks rather than traveling 

uphill).

A catastrophic blowout that occurs above the seabed (at the rig, along the riser between the seafloor 

and sea surface, or through leak paths on the BOP/wellhead) would not disturb the sediment.

The use of subsea dispersants would increase the exposure of offshore benthic habitats to dispersed 

oil droplets in the water column, as well as the chemicals used in the dispersants. The use of subsea 

dispersants is not likely to occur for seafloor blowouts outside the well casing.

Impacts to Topographic Features

Impacts that occur to benthic organisms on topographic features as a result of a blowout would 

depend on the type of blowout, distance from the blowout, relief of the biological feature, and 

surrounding physical characteristics of the environment (e.g., turbidity). The NTL 2009-G39 

recommends the use of buffers to prevent blowouts in the immediate vicinity of a topographic feature or 

its associated biota. Much of the oil released from a blowout would rise to the sea surface, therefore 

minimizing the impact to benthic communities by direct oil exposure. However, small droplets of oil that 

are entrained in the water column for extended periods of time may migrate into No Activity Zones that 

surround the topographic feature. In addition, they may come in contact with PSBF’s. Although these 

small oil droplets will not sink themselves, they may attach to suspended particles in the water column 

and then be deposited on the seafloor (McAuliffe et al., 1975). The resultant long-term impacts, such as 

reduced recruitment success, reduced growth, and reduced coral cover as a result of impaired recruitment, 

are discussed in Phase 4 (Post-Spill, Long-Term Recovery and Response). Also, if the blowout were to 

occur beneath the seabed, suspension and subsequent deposition of disturbed sediment may smother 

localized areas of benthic communities, possibly including organisms within No Activity Zones or on 

PSBF’s.

Benthic communities on a topographic feature or PSBF exposed to large amounts of resuspended and 

deposited sediments following a catastrophic, subsurface blowout could be subject to sediment 

suffocation, exposure to resuspended toxic contaminants, and reduced light availability. Impacts to corals 

as a result of sedimentation would vary based on coral species, the height to which the coral grows, 

degree of sedimentation, length of exposure, burial depth, and the coral’s ability to clear the sediment. 

Impacts may range from sublethal effects such as reduced growth, alteration in form, and reduced 

recruitment and productivity to slower growth or death (Rogers, 1990). Corals may also experience 

discoloration or bleaching as a result of sediment exposure, although recovery from such exposure may 

occur within 1 month (Wesseling et al., 1999).

The initial blowout impact would be greatest to communities located in clear waters with little

suspended sediment that experience heavy sedimentation as a result of the blowout. Reef-building corals 
B-36 Central Planning Area Lease Sales 235, 241, and 247 EIS

are sensitive to turbidity and may be killed by heavy sedimentation (Rogers, 1990; Rice and Hunter, 

1992). However, it is unlikely that reef-building corals would experience heavy sedimentation as a result 

of a blowout because drilling activity is not allowed near sensitive organisms in the No Activity Zones 

based on the lease stipulations as described in NTL 2009-G39. The most sensitive organisms are also 

typically elevated above soft sediments, making them less likely to be buried. The lower levels of 

topographic banks and the PSBF’s, which are generally small features with only a few meters of relief, 

typically experience turbid conditions. Vigorous bottom currents (often generated by storms) frequently 

resuspend bottom sediments and bathe these features in turbid waters, which results in sedimentation. As 

a result, the organisms that live in this environment near the seafloor are those adapted to frequent 

sedimentation.

Initial impacts would be much less extreme in a turbid environment (Rogers, 1990). For example, the 

South Texas Banks exist in a relatively turbid environment (the Nepheloid Zone). They generally have 

lower relief than the farther offshore banks at the shelf edge, may have a sediment cover, and exhibit 

reduced biota. Sediment from a blowout, if it occurred nearby, may have a reduced impact on these 

communities compared with an open-water reef community, as these organisms are more tolerant of 

suspended sediment (Gittings et al., 1992). Many of the organisms that predominate in this community 

also grow tall enough to withstand the sedimentation that results from their turbid environment or have 

flexible structures that enable the passive removal of sediments (Gittings et al., 1992).

A portion or the entire rig may sink to the seafloor as a result of a blowout. The benthic features and 

communities upon which the rig settles would be destroyed or smothered. Encrusting organisms would 

be crushed by a rig if it lands on a topographic feature or PSBF. A settling rig may suspend sediments, 

which may smother nearby benthic communities if the sediment is redeposited on sensitive features. The 

habitats beneath the rig may be permanently lost; however, the rig itself may become an artificial reef

upon which epibenthic organisms may settle. The surrounding benthic communities that were smothered 

by sediment would repopulate from nearby stocks through spawning recruitment and immigration if the 

hard substrate upon which they live was not physically destroyed.

Phase 2—Offshore Spill

A spill from a shallow-water blowout could impact benthic communities on the continental shelf 

because of the blowout’s proximity to these habitats. The scenario (Table B-4) for a catastrophic spill on 

the continental shelf is assumed to last 2-5 months and to release 30,000 bbl per day. A total volume of 

0.9-3.0 MMbbl of South Louisiana midrange paraffinic sweet crude oil could be released, which will float 

(APIo >10). An anticipated 35,000 bbl of dispersant may be applied to the surface waters.

A spill from a deepwater blowout could also impact shelf communities if surface oil is transported to 

these areas. The scenario (Table B-4) for a catastrophic spill in deep water is assumed to last 4-6 months 

and to release 30,000-60,000 bbl per day. A total volume of 2.7-7.2 MMbbl of South Louisiana midrange 

paraffinic sweet crude oil will be released, which will float (APIo >10). Oil properties may change as it 

passes up the well and through the water column, and it may become emulsified. An anticipated 

33,000 bbl of dispersant may be applied to the surface waters and 16,500 bbl may be applied subsea. 

Weathering and dilution of the oil will also occur as it travels from its release point. It is unlikely that a 

subsurface plume from a deepwater blowout would impact shelf communities. The oil is anticipated to 

remain in deep water and be directed by water currents in the deep water. These currents do not typically 

transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 2008).

Impacts to Topographic Features

Impacts from Surface Oil

Sensitive reef communities flourish on topographic features and PSBF’s in the Gulf of Mexico. Their 

depth below the sea surface helps to protect these habitats from a surface oil spill. Rough seas may mix 

the oil into subsurface water layers, where it may impact sessile biota. The longer the amount of time the 

seas are rough, the greater the amount of oil from a surface slick would be mixed into the water column. 

Measurable amounts of oil have been documented to mix from the surface down to a 10-m (33-ft) water 

depth, although modeling exercises have indicated such oil may reach a water depth of 20 m (66 ft). At 

this depth, however, the oil is found at concentrations several orders of magnitude lower than the amount 

shown to have an effect on corals (Lange, 1985; McAuliffe et al., 1975 and 1981; Knap et al., 1985). 
Catastrophic Spill Event Analysis B-37

None of the topographic features or PSBF’s in the GOM are shallower than 10 m (33 ft), and only the 

Flower Garden Banks are shallower than 20 m (66 ft). Further detail on this catastrophic OSRA run is 

contained in Appendix C. 

Impacts from Subsurface Oil

The presence of a subsurface oil plume on the continental shelf from a shallow-water blowout may 

affect benthic communities on topographic features and PSBF’s. A majority of the oil released is 

expected to rise rapidly to the sea surface above the release point because of the specific gravity 

characteristics of the oil reserves in the GOM, thus not impacting sensitive benthic communities. If the 

oil is ejected under high pressure, oil droplets may become entrained in the water column (Boehm and 

Fiest, 1982; Adcroft et al., 2010). The upward movement of the oil may be reduced if methane mixed 

with the oil is dissolved into the water column, reducing the oil’s buoyancy and slowing its rise to the 

surface (Adcroft et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, 

formed by vigorous turbulence in the plume or the injection of dispersants, may remain neutrally buoyant 

in the water column, creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). 

Dispersed oil in the water column begins to biodegrade and may flocculate with particulate matter, 

promoting sinking of the particles. Subsurface plumes generated by high-pressure dissolution of oil may 

come in contact with topographic features and PSBF’s. A sustained spill would continuously create 

surface slicks and possibly subsurface spill plumes. Some of the oil in the water column will become 

diluted or evaporated over time, reducing any localized transport to the seafloor (Vandermeulen, 1982). 

In addition, microbial degradation of the oil occurs in the water column so that the oil would be less toxic 

as it travels from the source (Hazen et al., 2010). However, a sustained spill may result in elevated 

exposure concentrations to benthic communities if the plume reaches them. The longer the spill takes to 

stop, the longer the exposure time and higher the exposure concentration may be.

The PSBF’s have a greater chance of being impacted by subsea plumes than topographic features

because currents tend to sweep around topographic features (Rezak et al., 1983; McGrail, 1982). The 

lower relief PSBF’s may fall in the path of the plume because the feature is not large enough to divert a 

current. Low-level exposures of corals to oil from a subsea plume may result in chronic or temporary 

impacts. For example, feeding activity or reproductive ability may be reduced when coral is exposed to 

low levels of oil; however, impacts may be temporary or unable to be measured over time. Experimental 

simulations of exposure indicated that normal feeding activity of Porites porites and Madracis asperula

were reduced when exposed to 50 ppm oil (Lewis, 1971). In addition, reefs of Siderastrea siderea that 

were oiled in a spill produced smaller gonads than unoiled reefs, resulting in reproductive stress (Guzmán 

and Holst, 1993).

Elevated concentrations of oil may be necessary to measure reduced photosynthesis or growth in 

corals. Photosynthesis of the zooxanthellae in Diplora strigosa exposed to approximately 18-20 ppm 

crude oil for 8 hours was not measurably affected, although other experiments indicate that 

photosynthesis may be impaired at higher concentrations (Cook and Knap, 1983). Measurable growth of 

Diploria strigosa exposed to oil concentrations up to 50 ppm for 6-24 hours did not show any reduced 

growth after 1 year (Dodge et al., 1984).

Corals exposed to subsea oil plumes may incorporate petroleum hydrocarbons into their tissue. 

Records indicate that Siderastrea siderea, Diploria strigosa, and Montastrea annularis accumulate oil 

from the water column and incorporate petroleum hydrocarbons into their tissues (Burns and Knap, 1989; 

Knap et al., 1982; Kennedy et al., 1992). Most of the petroleum hydrocarbons are incorporated into the 

coral tissues, not their mucus (Knap et al., 1982). However, hydrocarbon uptake may also modify lipid 

ratios of coral (Burns and Knap, 1989). If lipid ratios are modified, mucus synthesis may be impacted, 

adversely affecting the coral’s ability to protect itself from oil through mucus production (Burns and 

Knap, 1989).

It is unlikely that a subsurface plume from a deepwater blowout would impact shelf communities. 

The oil is anticipated to remain in deep water and be directed by water currents in the deep water. These 

currents do not typically transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 

2008).
B-38 Central Planning Area Lease Sales 235, 241, and 247 EIS

Impacts from Dispersed Oil

If dispersants are used at the sea surface, oil may mix into the water column, or if applied subsea, they 

can travel with currents through the water and may contact or settle on sensitive features. Note that, as 

indicated above, a deepwater plume would not travel onto the continental shelf, but a plume formed on 

the continental shelf could impact topographic features and PSBF’s. If located near the source, the 

dispersed oil could be concentrated enough to harm the community. If the oil remains suspended for a 

longer period of time, it would be more dispersed and exist at lower concentrations. Reports on 

dispersant usage on surface oil indicate that a majority of the dispersed oil remains in the top 10 m (33 ft) 

of the water column, with 60 percent of the oil in the top 2 m (6 ft) (McAuliffe et al., 1981). Dispersant 

usage also reduces the oil’s ability to stick to particles in the water column, minimizing oil adhering to 

sediments and traveling to the seafloor (McAuliffe et al., 1981). There is very little information on the 

behavior of subsea dispersants.

Dispersed oil reaching the topographic features and PSBF’s in the Gulf of Mexico would be expected 

to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981). Such concentrations would not be life 

threatening to larval or adult stages at the depth of the features based on experiments conducted with 

coral. Any dispersed oil in the water column that comes in contact with corals may evoke short-term 

negative responses by the organisms (Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 1984).

Reductions in feeding and photosynthesis could occur in coral exposed to dispersed oil. Short-term, 

sublethal responses of Diploria strigosa were reported after exposure to dispersed oil at a concentration of 

20 ppm for 24 hours. Although concentrations in this experiment were higher than what is anticipated for 

dispersed oil at depth, effects exhibited included mesenterial filament extrusion, extreme tissue 

contraction, tentacle retraction, and localized tissue rupture (Wyers et al., 1986). Normal behavior 

resumed within 2 hours to 4 days after exposure (Wyers et al., 1986). Diploria strigosa exposed to 

dispersed oil (20:1, oil:dispersant) showed an 85 percent reduction in zooxanthellae photosynthesis after 

8 hours of exposure to the mixture (Cook and Knap, 1983). However, the response was short term, as 

recovery occurred between 5 and 24 hours after exposure and return to clean seawater. Investigations 

1 year after Diploria strigosa was exposed to concentrations of dispersed oil between 1 and 50 ppm for 

periods between 6 and 24 hours did not reveal any impacts to growth (Dodge et al., 1984).

Historical studies indicate dispersed oil to be more toxic to coral species than oil or dispersant alone. 

The greater toxicity may be a result of an increased number of oil droplets caused by the use of 

dispersant, resulting in greater contact area between oil, dispersant, and water (Elgershuizen and 

De Kruijf, 1976). The dispersant causes a higher water-soluble amount of oil to contact the cell 

membranes of the coral (Elgershuizen and De Kruijf, 1976). The mucus produced by coral, however, can 

protect the organism from oil. Both hard and soft corals have the ability to produce mucus, and mucus 

production has been shown to increase when corals are exposed to crude oil (Mitchell and Chet, 1975; 

Ducklow and Mitchell, 1979). Dispersed oil, however, which has very small oil droplets, does not appear 

to adhere to coral mucus, and larger untreated oil droplets may become trapped by the mucus barrier 

(Knap, 1987; Wyers et al., 1986). However, entrapment of the larger oil droplets may increase the coral’s 

long-term exposure to oil if the mucus is not shed in a timely manner (Knap, 1987; Bak and Elgershuizen, 

1976). Additionally, more recent field studies, using more realistic concentrations of dispersants did not 

result in the toxicity historically reported (Yender and Michel, 2010).

Although historical studies indicated dispersed oil may be more toxic than untreated oil to corals 

during exposure experiments, untreated oil may remain in the ecosystem for long periods of time, while 

dispersed oil does not (Baca et al., 2005; Ward et al., 2003). Twenty years after an experimental oil spill

in Panama, oil and impacts from untreated oil were still observed at oil treatment sites, but no oil or 

impacts were observed at dispersed oil or reference sites (Baca et al., 2005). Long-term recovery of the 

coral at the dispersed oil site had already occurred as reported in a 10-year monitoring update, and the site 

was not significantly different from the reference site (Ward et al., 2003).

Impacts from Oil Adhering to Sediments

BOEM’s policy, as described in NTL 2009-G39, prevents wells from being placed immediately 

adjacent to sensitive communities. In the event of a seafloor blowout, however, some oil could be carried 

to topographic features or PSBF’s as a result of oil droplets adhering to suspended particles in the water 

column. Oiled sediment that settles to the seafloor may affect organisms attached to hard-bottom 
Catastrophic Spill Event Analysis B-39

substrates. Impacts may include reduced recruitment success, reduced growth, and reduced coral cover as 

a result of impaired recruitment. Experiments have shown that the presence of oil on available substrate 

for larval coral settlement has inhibited larval metamorphosis and larval settlement in the area. An 

increase in the number of deformed polyps after metamorphosis also took place because of exposure to oil 

(Kushmaro et al., 1997).

The majority of organisms exposed to sedimented oil, however, are anticipated to experience lowlevel concentrations because as the oiled sediments settle to the seafloor they are widely distributed. 

Coral may also be able to protect itself from low concentrations of sedimented oil that settles from the 

water column. Coral mucus may not only act as a barrier to protect coral from the oil in the water 

column, but it has also been shown to aid in the removal of oiled sediment on coral surfaces (Bak and 

Elgershuizen, 1976). Coral may use a combination of increased mucus production and the action of cilia 

to rid themselves of oiled sediment (Bak and Elgershuizen, 1976).

Impacts from Oil-Spill-Response Activity

Oil-spill-response activity may also impact sessile benthic features. Booms anchored to the seafloor 

are sometimes used to control the movement of oil at the water surface. Boom anchors can physically 

impact corals and other sessile benthic organisms, especially when booms are moved around by waves 

(Tokotch, 2010). Vessel anchorage and decontamination stations set up during response efforts may also 

break or kill PSBF’s if their location is unmapped and anchors are set on the features. Injury to coral 

reefs as a result of anchor impact may result in long-lasting damage or failed recovery (Rogers and 

Garrison, 2001). Effort should be made to keep vessel anchorage areas as far from sensitive benthic 

features as possible to minimize impact.

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 

buried. Based on stipulations as described in NTL 2009-G39, a well should be far enough away from a 

topographic feature to prevent extruded drilling muds from smothering sensitive benthic communities. 

However, if drilling muds were to travel far enough or high enough in the water column to contact a 

sensitive community, the fluid would smother the existing community. Experiments indicate that corals 

perish faster when buried beneath drilling mud than when buried beneath carbonate sediments 

(Thompson, 1980). Burial may lead to the elimination of a live bottom community.

Phase 3—Onshore Contact

There would likely be no adverse impacts to topographic features and PSBF’s as a result of the events 

and the potential impact-producing factors that could occur throughout Phase 3 of a catastrophic spill 

because the topographic features and PSBF’s are located offshore.

Phase 4—Post-Spill, Long-Term Recovery and Response

Topographic features and PSBF’s exposed to large amounts of resuspended sediments following a 

catastrophic, subsurface blowout could be subject to sediment suffocation, exposure to resuspended toxic 

contaminants, and reduced light penetration. The greatest impacts would occur to communities that exist 

in clear water with very low turbidity. The consequences of a blowout along, directly on, or near one of 

these features could be long lasting, although the occurrence of a blowout near such sensitive 

communities is unlikely because of stipulations described in NTL 2009-G39, which prevents drilling 

activity near sensitive hard-bottom habitats. Impacts to a community in more turbid waters, such as the 

South Texas Banks, would be greatly reduced, as the species on these features are tolerant of suspended 

sediments, and recovery would occur quicker.

Impacts may also occur from low-level or long-term oil exposure. This type of exposure has the 

potential to impact reef communities, resulting in impaired health. Recovery may be fairly rapid from 

brief, low-level exposures, but it could be much longer with acute concentrations or long-term exposure 

to oil, such as in observations from Panama where untreated oil remained in the ecosystem for long 

periods of time, inhibiting coral recovery (Baca et al., 2005; Ward et al., 2003). Recovery time would 

therefore depend on recruitment from outside populations that were not affected by oiling and residence 

time of oil in an ecosystem.
B-40 Central Planning Area Lease Sales 235, 241, and 247 EIS

Overall Summary and Conclusion (Phases 1-4)

A catastrophic spill on the continental shelf would have a greater impact on topographic features and 

PSBF’s than a deepwater spill. Surface oil from a deepwater spill would be weathered and diluted by the 

time it reaches the surface waters over topographic features and PSBF’s (if it ever reaches them), and it 

would be unlikely that it would mix to the depth of active growth in concentrations that could cause 

toxicity. Subsea plumes formed in deepwater would not travel onto the continental shelf because deepsea currents do not travel up a slope.

A catastrophic blowout and spill on the continental shelf has a greater chance to impact topographic 

features and PSBF’s. If the blowout occurs close enough to sensitive features, the organisms may be 

smothered by settling sediment that was displaced by the blowout. The farther the feature is from the 

blowout, the less its chance of being covered with settling sediment or sediment upon which oil adhered. 

In addition, distancing oil and gas activities from topographic features prevents the settlement of a sinking 

rig on top of a topographic feature, although it may destroy a PSBF.

In most cases, impacts from oil would be sublethal. Surface oil is not expected to mix to the zone of 

active growth, and any oil components that do reach that depth would be in sublethal concentrations. 

Subsea plumes may contact the features; however, because currents tend to travel around, instead of over, 

topographic features, the topographic features should be protected from subsea plumes, while lower relief 

PSBF’s may be impacted. Overall impacts of dispersed oil would be similar to subsea plumes. Spill 

response activity should not impact topographic features because it is unlikely that vessels would anchor 

on the features, but they could anchor on unmapped, lower relief PSBF’s.

Overall, a catastrophic spill would have a low probability of impacting topographic features because 

of the distancing requirements included in leases, as described in NTL 2009-G39, of oil and gas activities 

from topographic features, the depth of mixing of surface oil compared with the depth of the active 

growing zone, currents that sweep around the topographic features, and the weathering and dispersion of 

oil that would occur with distance from the source as it travels toward the features. The PSBF’s could 

have greater impacts from a blowout as oil and gas activities are not as far distanced from them as 

topographic features; they have a lower relief than topographic features, which would not divert currents; 

and the locations of these features are not all known so accidental anchor impacts may result in breakage 

of the features and possibly destruction. The PSBF’s would, however, have similar protection as for 

topographic features from surface oil.

B.3.1.8. Sargassum Communities

Pelagic Sargassum algae is a floating brown algae that occurs in all parts of the GOM throughout the 

year. It has a seasonal cycle so that its abundance greatly increases spring through fall, when it is carried 

by water currents around the south of Florida and then up the east coast (Gower and King, 2011). It 

occurs in patches, floating on and near the sea surface. Wind and water currents commonly drive it into 

long lines or windrows; when conditions are turbulent, it becomes more scattered and mixed into the 

upper water column. A key to understanding impacts to Sargassum is that the algae is ubiquitous and 

occurs in scattered patches in the very top part of the water column. Sargassum also provides habitat for 

pelagic species, including fish, invertebrates, and sea turtles. 

Phase 1—Initial Event

During the initial phase of a catastrophic blowout, impacts may include disturbance of sediments, 

destruction of the drilling rig, release of oil and natural gas (methane), and emergency response efforts. 

This chapter deals with the immediate effects of a blowout that would be located at least 3 nmi (3.5 mi; 

5.6 km) from shore.

Since Sargassum is a floating pelagic (open ocean) algae, it would only be affected by impacts that 

occur in the top-most part of the water column. In deep water (≥ 300 m, 984 ft), sediment disturbed by 

the blowout would not affect Sargassum because the sediment would not reach the surface waters. 

However, in shallow water, sediment from a blowout could have minor effects on Sargassum algae in the 

immediate vicinity. The sediment would have little effect on the algae itself, producing only slight, 

temporary silting that could reduce photosynthesis. If the sediment is contaminated with oil, then the oil 

could have adverse effects on the algae. Depending on the severity of oiling, the algae could be damaged 

or destroyed; but this would only affect the algae in the local vicinity of the blowout. Sediment and oil 
Catastrophic Spill Event Analysis B-41

would have a more acute effect on the associated invertebrate, fish, and sea turtle community that utilizes 

the habitat of the Sargassum. Impacts to these organisms may include “changes in respiration rate, 

abrasion and puncturing of structures, reduced feeding, reduced water filtration rates, smothering, delayed 

or reduced hatching of eggs, reduced larval growth or development, abnormal larval development, or 

reduced response to physical stimulus” (Anchor Environmental CA, L.P., 2003).

Destruction of the oil drilling rig and associated equipment could have an acute effect on patches of 

Sargassum algae that happen to be caught in the structure (if it sinks) or destroyed by fuel leaks and 

possible fire on the sea surface. This could destroy local patches of Sargassum, but it would have no 

measurable effect on the Sargassum community as a whole.

The release of oil during the initial blowout event would be expected to cover local patches of 

Sargassum algae with oil, destroying the algae and associated organisms. Methane gas may also bathe 

local patches of algae as it rises through the sea surface; it would have little effect on the algae itself but 

may poison associated organisms. The initiation of oil and gas release (as defined for this phase) at the 

site of the blowout event would affect only local patches of Sargassum, but it would have no measurable 

effect on the Sargassum community as a whole.

Emergency response activities would have minor impacts to Sargassum algae that comes in contact 

with vessels. This is mostly the simple impingement of the algae on the ships’ water intake screens, 

including water that may be pumped in fire-fighting efforts. This minor and local effect would have no 

measurable effect on the Sargassum community as a whole.

Phase 2—Offshore Spill

During the second phase of a catastrophic blowout, the major impact of concern is the release of oil 

and methane over time. Response efforts may produce additional minor impacts to Sargassum. This 

chapter deals with the growing effects of a blowout that releases oil and methane into the offshore 

environment.

Since Sargassum is a floating pelagic (open ocean) algae, it would be affected by impacts that occur 

in the top-most part of the water column. This makes Sargassum habitat particularly susceptible to 

damage from offshore oil spills. Oceanographic processes that concentrate Sargassum into mats and rafts 

would also concentrate toxic substances. Therefore, it may be assumed that Sargassum would be found in 

areas where oil, dispersants, and other chemicals have accumulated following a catastrophic spill. Oil 

spreads on the sea surface to form extremely thin layers (0.01-0.1 micrometers) that cover large areas 

(MacDonald et al., 1996). Since Sargassum is ubiquitous in surface waters of the GOM, oil spreading on 

the sea surface can be expected to coincide with floating mats of the algae. The larger the quantity of 

spill and the longer it flows, the larger the area of sea surface it would cover. A catastrophic spill would 

cover a large area and result in impacts to a large quantity of Sargassum algae. For example, Macondo

well oil spill covered up to one-third of the northern GOM (McCrea and Pauly, 2011; USDOC, NMFS, 

2011a) and may have affected about one-third of the Sargassum algae in the northern GOM at the time.

The severity of oiling to Sargassum depends largely on physical conditions. Factors include the 

quantity of oil at a particular launch point and its physical state, distance from the source, weather 

conditions, and the possible use of dispersants. Further detail on this catastrophic OSRA run is contained 

in Appendix C. 

Obviously, more oil leads to increased oiling, but the physical state of the oil changes as it weathers, 

biodegrades, dissipates, and emulsifies over time and distance. Storms can mix oil into the water column

(expected maximum of 10-20 m [33-66 ft]; Lange, 1985; McAuliffe et al., 1975 and 1981; Knap et al., 

1985; Scarlett et al., 2005; Hemmer et al., 2010; George-Ares and Clark, 2000), possibly increasing its 

contact with Sargassum as it also mixes the Sargassum into the water column. However, when storms are 

not mixing the oil, they are also not mixing the Sargassum, so the Sargassum would float near the sea 

surface, just as the oil would. Convergence zones, places in the ocean where strong opposing currents 

meet, would collect both oil and Sargassum. Sea turtles, especially post-hatchlings and juveniles, use 

these areas for food and cover. Witherington et al. (2012) surveyed sea turtles in the eastern Gulf of 

Mexico and Atlantic Ocean off Florida and found that 89 percent of the turtles documented were observed 

within 1 m (3 ft) of floating Sargassum. The use of dispersants on surface oil slicks could increase the 

exposure of Sargassum to oil by promoting mixing of oil into the upper few meters of the water column. 

This also promotes the dispersion of oil, speeding its decline toward low concentrations that would be less 

toxic. Regardless, any exposure that is enough to cause visible oiling can be expected to have significant 
B-42 Central Planning Area Lease Sales 235, 241, and 247 EIS

detrimental effects on the organisms associated with Sargassum and, likely, effects on the Sargassum

itself. Heavy oiling of Sargassum near the source of the spill would destroy the affected algae. Very 

light exposure far from the oil source may have little effect.

The specific effects of oil on Sargassum depend on the severity of oiling. High to moderate levels of 

oiling would likely cause complete mortality. Low levels of exposure may result in a range of sublethal 

effects to the algae and its associated community. There are no published studies of the effects of oil on 

Sargassum or its associates, but numerous studies of similar organisms in benthic habitats can suggest 

expected results. Sublethal responses in organisms associated with Sargassum may occur at 

concentrations as low as 1-10 ppb (Hyland and Schneider, 1976). Rogers (1990) documented impacts 

such as reduced growth, alteration in form, and reduced recruitment and productivity. Other sublethal 

impacts may include reduced feeding rates, reduced ability to detect food, erratic movement, ciliary 

inhibition, tentacle retraction, reduced movement, decreased aggression, and altered respiration (Scarlett 

et al., 2005; Suchanek, 1993). Embryonic life stages of organisms may experience toxicity at lower levels 

than the adult stages (Fucik et al., 1995; Suchanek, 1993; Beiras and Saco-Álvarez, 2006; Byrne, 1989). 

The algae itself would be less sensitive than many of its associates, since the algae produces oils of its 

own and has a waxy coating that may protect it from physical oiling.

Response efforts aimed at removing oil from the affected area would have minor impacts on 

Sargassum algae as well. Response vessels would impinge a small amount of the algae on their 

propellers and cooling-water intakes. Cleanup processes such as booming, skimming, and in-situ burning 

would also trap and destroy patches of Sargassum; however, these activities would take place in areas of 

high concentration of surface oil, where Sargassum would likely be destroyed by oil contamination even 

if the cleanup activity were absent.

Phase 3—Onshore Contact

This third phase of a catastrophic blowout focuses on the approach of oil to the shoreline. This 

involves the possible oiling of coastal resources including beaches, wetlands, SAV and seagrasses, the 

shallow seafloor, and any resources drifting in the water column (e.g., Sargassum). Response efforts can 

produce additional serious impacts.

There would likely be little additional impact to pelagic Sargassum algae as oil approaches a 

shoreline. Since both the algae and surface oil approaching shore would be guided by the same forces 

(wind and water currents), they would likely be already traveling together, with the algae already 

contaminated. Once it is onshore, the Sargassum would die, regardless of oil contamination. Sargassum

that washes ashore has some value to the ecosystem as it provides food and shelter for some organisms as 

it decays. This value would be mostly lost if the Sargassum is oiled when it reaches shore.

Phase 4—Post-Spill, Long-Term Recovery and Response

The final phase of a catastrophic blowout is the long-term response of the ecosystem and its recovery. 

Both, the natural rate of recovery and the persistence of oil in natural habitats over time determine the 

long-term effects. Contaminants biodegrade over time, but they may become sequestered as inert forms 

(e.g., buried in sediment) until disturbed (by storms) and re-activated, producing renewed impacts.

Sargassum algae has a yearly seasonal cycle of growth and a yearly cycle of migration from the GOM 

to the western Atlantic. A catastrophic spill could affect a large portion of the annual crop of the algae. 

A large event, such as the Macondo well blowout and spill, could reduce the standing crop of Sargassum

in the GOM and subsequently in the western Atlantic. This could have a cascading effect down current 

(in the Atlantic) that would stress the cycles of other organisms that depend on the Sargassum habitat. 

However, the effect can be expected to diminish with remoteness from the direct impacts of the spill, i.e., 

the algae community itself would be most affected, with lesser effects on organisms that utilize the habitat 

as a nursery, for feeding, as shelter, or other purposes.

While a large spill event could affect a large portion of the standing crop of Sargassum, several 

factors contribute to the quick recovery of the habitat. Sargassum algae is predominately found in the 

open-ocean pelagic habitat. Once the spill event subsides, the pelagic habitat would quickly regain its 

typically very high water quality. The pelagic habitat far from shore is also far from land-based sources 

of pollution. Only part of the Sargassum stocks would be affected; algae not affected by the spill event 

would continue to grow normally and repopulate the habitat. Since Sargassum has a seasonal cycle of 
Catastrophic Spill Event Analysis B-43

growth in the summer and reduction in the winter, populations in the winter following a catastrophic 

event may be similar to populations of any other year. Relatively small populations survive each winter, 

subsequently repopulating the habitat each year. With this pattern, recovery from the effects of a 

catastrophic event is expected within 1-2 growing seasons.

Overall Summary and Conclusion (Phases 1-4)

Pelagic Sargassum algae is one of the most likely habitats to be affected by a catastrophic offshore oil 

spill; however, because of its ubiquitous distribution and seasonal cycle, recovery is expected within 

1-2 years. Sargassum algae floats on and near the sea surface and occurs in patches that can be collated 

into windrows by wind and water currents. Oil from a spill offshore would accumulate in the same 

waters, making it inevitable that some patches of Sargassum would be severely affected.

The initial catastrophic event (Phase 1) could destroy Sargassum patches in the immediate vicinity of 

the accident. Impingement, fire, and the initial concentrated spillage of oil and fuels would destroy local 

patches. Sediments disturbed by the accident would only affect Sargassum if the event occurred in 

shallow waters.

The duration of the spill event (Phase 2) would have the most effect on floating Sargassum algae. 

Patches of algae within the entire coverage of the oil slick would be subject to severe damage and death. 

Algae in areas farther from the spill, receiving lower level impacts, may still suffer damage, especially the 

sensitive invertebrate and fish communities associated with the habitat. Efforts to remove the oil could 

gather Sargassum with the oil, but these algae patches would likely be destroyed by the oil anyway since 

the collection activities would occur in areas of concentrated oil.

As oil approaches shore (Phase 3), impacts to floating Sargassum algae would not increase much, as 

the algae would likely already be exposed to the oil since wind and water currents drive both the algae 

and the oil.

The recovery of floating Sargassum algae (Phase 4) may occur within 1-2 years because the algae has 

a yearly cycle of subsidence and re-growth. The pelagic habitat would quickly regain its high level of 

water quality after the cessation of a spill. Not all of the Sargassum habitat would be affected, even by a 

catastrophic spill; healthy algae would continue to grow and replenish the population. Within 1-2 years, 

the Sargassum algae community may have completely recovered from the impacts of a catastrophic spill.

B.3.1.9. Chemosynthetic Deepwater Benthic Communities

Deepwater benthic communities of the Gulf of Mexico include soft bottom, chemosynthetic, and 

coral habitats. Deep water, for ecology in the GOM, is defined as water depths over 300 m (984 ft) 

because chemosynthetic communities and Lophelia coral habitats have not been found in waters 

shallower than these depths. The possible impacts to these benthic communities from a catastrophic 

blowout depend on the location and the nature of the event.

Phase 1—Initial Event

During the initial phase of a catastrophic blowout, impacts may include the disturbance of sediments, 

destruction of the drilling rig, release of oil and natural gas (methane), and emergency response efforts. 

This chapter deals with the immediate effects of a blowout located at least 3 nmi (3.5 mi; 5.6 km) from 

shore.

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. Some fine sediment could travel up to a few 

thousand meters before redeposition, negatively impacting a localized area of benthic communities. If a 

blowout were to occur close enough to a chemosynthetic community, suspended sediment may impact the 

organisms. Restrictions described in NTL 2009-G40 require drilling to be removed at least 610 m 

(2,000 ft) from possible chemosynthetic communities. During a blowout, sediment may become 

contaminated with oil and subsequently deposit that oil down-current from the source. The highest 

concentrations of contamination would be nearest the well, and concentrations would diminish with 

distance. A catastrophic blowout that occurs above the seabed (at the rig, along the riser between the 

seafloor and sea surface, or through leak paths on the BOP/wellhead) would not disturb the sediment.
B-44 Central Planning Area Lease Sales 235, 241, and 247 EIS

Destruction of the oil drilling rig and associated equipment could have an acute effect on any 

chemosynthetic communities caught under the direct impact of the equipment when it falls to the seafloor. 

However, the restrictions described in NTL 2009-G40 require drilling locations to be 610 m (2,000 ft) 

from any possible indications of chemosynthetic communities, reducing the possibility that a rig would 

settle directly on sensitive habitat.

A catastrophic blowout would likely result in released oil rapidly rising to the sea surface because 

typical reserves in the GOM have specific gravity characteristics that are much lighter than water (refer to 

Chapter 3.2.1.3 of this Supplemental EIS; Environment Canada, 2011; Trudel et al., 2001). The oil 

would surface almost directly over the source location. Oil floating to the sea surface would be 

effectively removed from affecting chemosynthetic communities on the seafloor. Even oil treated with 

chemical dispersants on the sea surface would not be expected to have widespread impacts to deepwater

communities. Reports on dispersant usage on surface oil indicate that a majority of the dispersed oil 

remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (6 ft) 

(McAuliffe et al., 1981a; Lewis and Aurand, 1997). Lubchenco et al. (2010) reports that chemically 

dispersed surface oil from the Macondo well blowout and oil spill remained in the top 6 m (20 ft) of the 

water column where it mixed with surrounding waters and biodegraded. However, if the oil is ejected 

under high pressure, micro-droplets of oil may form and become entrained in the water column (Boehm 

and Fiest, 1982; Adcroft et al., 2010). Upward movement of oil may also be reduced if methane mixed 

with the oil is dissolved into the water column, reducing the buoyancy of the oil/gas stream (Adcroft 

et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by vigorous 

turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the water column, 

creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010a). It is unlikely that any 

chemosynthetic community would be affected by the initial stage of a catastrophic event due to the 

required separation of drilling activities from sensitive habitats, because released oil would rise rapidly to 

a level above the habitat, and because surface oil would not mix to the depths of the chemosynthetic 

communities. The required separation distance would also allow for a subsea plume to mix with the 

surrounding water and become diluted before it reached a deepwater community.

Phase 2—Offshore Spill

During the second phase of a catastrophic blowout, the major impact of concern is the release of oil 

and methane over time. Response efforts may produce additional impacts. This chapter deals with the 

growing effects of a blowout that releases oil and methane into the offshore environment.

A spill resulting from a catastrophic blowout in deep water has the potential to impact offshore 

benthic communities; however, it is not likely that deepwater benthic communities would be affected by a 

spill from a shallow-water blowout. Although subsurface plumes can be generated when oil is ejected 

under high pressure or dispersants are used subsea, a majority of the oil originating from a seafloor 

blowout in deep water is expected to rise rapidly to the sea surface. Upward movement of the oil may 

also be reduced if methane mixed with the oil is dissolved into the water (Adcroft et al., 2010). A 

sustained spill would continuously create surface slicks and possibly subsurface spill plumes. Some of 

the oil in the water column would become diluted over time, reducing transport to the seafloor 

(Vandermeulen, 1982). Concentrations of dispersed and dissolved oil in the Macondo well blowout and 

spill subsea plume were reported to be in the part per million range or less and were generally lower away 

from the water’s surface and away from the wellhead (Adcroft et al., 2010; Haddad and Murawski, 2010; 

Joint Analysis Group, 2010; Lubchenco et al., 2010). In addition, microbial degradation of oil occurs in 

the water column rendering oil less toxic when it contacts the seafloor (Hazen et al., 2010). Oil can 

precipitate to the seafloor by adhering to other particles, much like rainfall (Kingston et al., 1995; 

International Tanker Owners Pollution Federation Limited, 2007). Oil would also reach the seafloor 

through planktonic consumption and associated excretion, which is distributed over the seafloor 

(International Tanker Owners Pollution Federation Limited, 2007). These mechanisms would result in a 

wide distribution of small amounts of oil. Throughout these processes, oil would be biodegraded from 

bacterial action, which would continue on the seafloor, resulting in scattered microhabitats with an 

enriched carbon environment (Hazen et al., 2010).

A sustained spill may result in elevated exposure concentrations to chemosynthetic features if a 

subsea oil plume contacts them directly. Dispersed oil is mixed with water, and its movement is then 

dictated by water currents and the physical, chemical, and biodegradation pathways. BOEM’s policy 
Catastrophic Spill Event Analysis B-45

(refer to NTL 2009-G39) prevents wells from being placed immediately adjacent to sensitive 

communities; however, in the event of a seafloor blowout, some oil could be carried to chemosynthetic 

communities by subsea plumes. Impacts may include reduced recruitment success, reduced growth, and 

reduced biological cover as a result of impaired recruitment. Concentrated oil plumes reaching 

chemosynthetic communities could cause oiling of organisms, resulting in the death of entire populations 

on localized sensitive habitats. The longer the oil remains suspended in the water column, the more 

dispersed, less concentrated, and more biodegraded it would become. Depending on how long oil 

remained suspended in the water column, it may be thoroughly degraded by biological action before 

contacting the seafloor (Hazen et al., 2010; Valentine et al., 2010). Biodegradation rates in cold, 

deepwater environments are not well understood at this time. In general, potential impacts to 

chemosynthetic communities would be localized due to the directional movement of oil plumes by the 

water currents and because the sensitive habitats have a scattered, patchy distribution. While a few patch 

habitats may be affected, the Gulfwide ecosystem of chemosynthetic communities would be expected to 

suffer no significant effects.

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 

buried. Based on stipulations as described in NTL 2009-G40, a well should be far enough away from a 

chemosynthetic community to prevent extruded drilling muds from smothering sensitive benthic

communities.

Phase 3—Onshore Contact

The third phase of a catastrophic blowout focuses on the approach of oil to the shoreline. This 

involves the possible oiling of coastal resources including beaches, wetlands, SAV and seagrasses, the 

shallow seafloor, and any resources drifting in the water column. Response efforts can produce additional 

serious impacts. There would be no additional adverse impacts to chemosynthetic communities in deep 

water as a result of the events and the potential impact-producing factors that could occur throughout 

Phase 3 of a catastrophic spill because the chemosynthetic communities are located offshore in deep 

water (>300 m, 610 ft).

Phase 4— Post-Spill, Long-Term Recovery and Response

The final phase of a catastrophic blowout is the long-term response of the ecosystem and its recovery. 

Both the natural rate of recovery and the persistence of oil in natural habitats over time determine what 

long-term effects may occur. Contaminants degrade over time but may become sequestered as inert 

forms (e.g., buried in sediment) until disturbed and reactivated, producing renewed impacts.

If oil is ejected under high pressure or dispersants are applied at the source near the seafloor, oil 

would mix into the water column, be carried by underwater currents, and eventually contact the seafloor 

in some form, either concentrated (near the source) or dispersed and decayed (farther from the source). 

The oil could then impact patches of chemosynthetic community habitat in its path. The farther the 

dispersed oil travels, the more diluted it would become as it mixes with surrounding water. 

Chemosynthetic communities located at more than 610 m (2,000 ft) away from a blowout could 

experience minor impacts from suspended sediments that travel with currents, although the sediment 

concentration would be diluted with distance from the well. Studies indicate that periods of decades to 

hundreds of years are required to reestablish a seep community once it has disappeared (depending on the 

community type) (Powell, 1995; Fisher, 1995). There is evidence that substantial impacts on these 

communities could permanently prevent reestablishment, particularly if hard substrate required for 

recolonization is buried by resuspended sediments from a blowout. A catastrophic spill combined with 

the application of dispersant has the potential to cause devastating effects on local patches of habitat in 

the path of subsea plumes where they physically contact the seafloor. Sublethal effects are possible for 

communities that receive a lower level of impact. Examples of these effects could include temporary lack 

of feeding, expenditure of energy to remove the oil, loss of gametes and reproductive delays, and loss of 

tissue mass. Oil plumes that remain in the water column for longer periods would disperse and decay, 

having only minimal effect. Depending on how long it remains in the water column, oil may be 

thoroughly degraded by biological action before contacting the seafloor. Water currents can carry a 
B-46 Central Planning Area Lease Sales 235, 241, and 247 EIS

plume to contact the seafloor directly but a more likely scenario would be for oil to adhere to other 

particles and precipitate to the seafloor, much like rainfall (Kingston et al., 1995; International Tanker 

Owners Pollution Federation Limited, 2007). Oil would also reach the seafloor through planktonic 

consumption and associated excretion, which is distributed over the seafloor (International Tanker 

Owners Pollution Federation Limited, 2007). These mechanisms would result in a wide distribution of 

small amounts of oil (or oil by-products). This oil would be in the process of biodegradation from 

bacterial action, which would continue on the seafloor, resulting in scattered microhabitats with an 

enriched carbon environment (Hazen et al., 2010). Habitats directly under the path of the oil plume as it 

disperses and “rains” down to the seafloor may experience minor effects, but since the oil would be 

deposited in a widely scattered and decayed state, little effect is anticipated.

Overall Summary and Conclusion (Phases 1-4)

Chemosynthetic communities would potentially be subject to detrimental effects from a catastrophic 

seafloor blowout. Sediment and oiled sediment from the initial event (Phase 1) are not likely to reach 

chemosynthetic communities in heavy amounts because of requirements described in NTL 2009-G40. 

Fine sediment from a blowout may reach the location of sensitive habitats, producing sublethal effects. 

The initial accident could result in the drilling rig and equipment falling on a sensitive seafloor habitat if 

the structure travels more than 610 m (2,000 ft) from the well site.

The ongoing spill event (Phase 2) would have the most effect on chemosynthetic communities. 

Chemosynthetic communities are at risk from subsea oil plumes that could directly contact localized 

patches of sensitive habitat. Oil plumes reaching chemosynthetic communities could cause oiling of 

organisms, resulting in the death of entire populations on localized sensitive habitats. However, potential 

impacts would be localized due to the directional movement of oil plumes by the water currents and 

because the sensitive habitats have a scattered, patchy distribution. The more likely scenario would be 

exposure to widely dispersed, biodegraded particles that “rain” down from a passing oil plume. While a 

few patch habitats may be affected, the Gulfwide ecosystem of chemosynthetic communities would be 

expected to suffer no significant effects.

As oil approaches shore (Phase 3), there would be no additional adverse impacts to chemosynthetic 

communities because the chemosynthetic communities are located offshore in deep water (>300 m; 

610 ft). 

The recovery of chemosynthetic communities (Phase 4) depends on the severity of initial impacts. A 

catastrophic spill combined with the application of dispersant has the potential to cause devastating 

effects on local patches of habitat in the path of subsea plumes where they physically contact the seafloor. 

Studies indicate that periods from decades to hundreds of years are required to reestablish a seep 

community once it has disappeared (depending on the community type) (Powell, 1995; Fisher, 1995). 

The burial of hard substrate could permanently prevent recovery. Sublethal effects are possible for 

communities that receive a lower level of impact. Examples of these effects could include temporary lack 

of feeding, expenditure of energy to remove the oil, loss of gametes and reproductive delays, and loss of 

tissue mass. However, most chemosynthetic community habitats are expected to experience no impacts 

from a catastrophic seafloor blowout because of the directional movement of oil plumes by the water 

currents and because the sensitive habitats have a scattered, patchy distribution.

B.3.1.10. Nonchemosynthetic Deepwater Benthic Communities

Deepwater benthic communities of the Gulf of Mexico include soft bottom, chemosynthetic, and live 

bottom communities (mostly deepwater coral communities). Deep water, for ecology in the GOM, is 

defined as water depths over 300 m (984 ft) because nonchemosynthetic communities and Lophelia coral 

habitats have not been found in waters shallower than these depths. The possible impacts to 

nonchemosynthetic deepwater benthic communities from a catastrophic blowout depend on the location 

and the nature of the event.

Phase 1—Initial Event

During the initial phase of a catastrophic blowout, impacts may include disturbance of sediments, 

destruction of the drilling rig, release of oil and natural gas (methane), and emergency response efforts. 
Catastrophic Spill Event Analysis B-47

This phase deals with the immediate effects of a blowout located at least 3 nmi (3.5 mi; 5.6 km) from 

shore.

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. A blowout that occurs outside the well casing 

can rapidly deposit 30 cm (12 in) or more of sediment within a few hundred meters and may smother 

much of the soft bottom community in a localized area. Some fine sediment could travel up to a few 

thousand meters before redeposition, negatively impacting a localized area of benthic communities. 

Many of the organisms on soft bottoms live within the sediment and have the ability to migrate upward in 

response to burial by sedimentation. In situations where soft bottom infaunal communities are negatively 

impacted, recolonization by populations from neighboring soft bottom substrate would be expected over a 

relatively short period of time for all size ranges of organisms, in a matter of days for bacteria and 

probably less than 1 year for most macrofauna and megafauna species. Recolonization could take longer 

for areas affected by direct contact of concentrated oil.

If a blowout were to occur close enough to a sensitive deepwater live bottom community, suspended 

sediment may impact the organisms. Restrictions described in NTL 2009-G40 require drilling to be 

removed at least 610 m (2,000 ft) from possible live bottom communities. During a blowout, suspended 

sediment may become contaminated with oil and subsequently deposit that oil down-current from the 

source. The highest concentrations of contamination would be nearest the well, and concentrations would 

diminish with distance. A catastrophic blowout that occurs above the seabed (at the rig, along the riser 

between the seafloor and sea surface, or through leak paths on the BOP/wellhead) would not disturb the 

sediment.

Destruction of the oil drilling rig and associated equipment could have an acute effect on any 

nonchemosynthetic communities caught under the direct impact of the equipment when it falls to the 

seafloor. However, the restrictions described in NTL 2009-G40 require drilling locations to be 610 m 

(2,000 ft) from any possible indications of sensitive live bottom communities, reducing the possibility 

that a rig would settle directly on sensitive habitat.

A catastrophic blowout would likely result in released oil rapidly rising to the sea surface because 

typical reserves in the GOM have specific gravity characteristics that are much lighter than water (refer to 

Chapter 3.2.1.3 of this Supplemental EIS; Environment Canada, 2011; Trudel et al., 2001). The oil 

would surface almost directly over the source location. Oil floating to the sea surface would be 

effectively removed from affecting nonchemosynthetic communities on the seafloor. Even oil treated 

with chemical dispersants on the sea surface would not be expected to have widespread impacts to 

deepwater communities. Reports on dispersant usage on surface oil indicate that a majority of the 

dispersed oil remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m 

(6 ft) (McAuliffe et al., 1981; Lewis and Aurand, 1997). Lubchenco et al. (2010) report that chemically 

dispersed surface oil from the Macondo well blowout and oil spill remained in the top 6 m (20 ft) of the 

water column where it mixed with surrounding waters and biodegraded. However, if the oil is ejected 

under high pressure, micro-droplets of oil may form and become entrained in the water column (Boehm 

and Fiest, 1982; Adcroft et al., 2010). Upward movement of the oil may also be reduced if methane 

mixed with the oil is dissolved into the water column, reducing the buoyancy of the oil/gas stream 

(Adcroft et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by 

vigorous turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the 

water column, creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). It is 

unlikely that any deepwater live bottom community would be affected by the initial stage of a 

catastrophic event due to the required separation of drilling activities from sensitive habitats, because 

released oil would rapidly rise to a level above the habitat, and because surface oil would not mix to the 

depths of such communities. The required separation distance would also allow for a subsea plume to 

mix with the surrounding water and become diluted before it reached a deepwater community.

Phase 2—Offshore Spill

During the second phase of a catastrophic blowout, the major impact of concern is the release of oil 

and methane over time. Response efforts may produce additional impacts. This chapter deals with the 

growing effects of a blowout that releases oil and methane into the offshore environment.
B-48 Central Planning Area Lease Sales 235, 241, and 247 EIS

A spill resulting from a catastrophic blowout in deep water has the potential to impact offshore 

benthic communities; however, it is not likely that deepwater benthic communities would be affected by a 

spill from a shallow-water blowout. Although subsurface plumes can be generated when oil is ejected 

under high pressure or when dispersants are used subsea, a majority of the oil originating from a seafloor 

blowout in deep water is expected to rise rapidly to the sea surface. Oil and chemical spills that originate 

at the sea surface are not considered to be a potential source of measurable impacts on deepwater, live 

bottom communities because of the water depths at which these communities are located. Oil spills at the 

surface would tend not to sink, and the risk of weathered components of a surface slick reaching the 

benthos in any measurable concentration would be very small. Surface oil also could not physically mix 

to depths of deepwater communities under natural conditions (Lange, 1985; McAuliffe et al., 1975; 

McAuliffe et al., 1981a; Tkalich and Chan, 2002).

Upward movement of the oil may also be reduced if methane mixed with the oil is dissolved into the 

water (Adcroft et al., 2010). A sustained spill would continuously create surface slicks and possibly 

subsurface spill plumes. One deepwater coral site at a depth of 1,370 m (4,495 ft) has been reported as 

severely damaged following the Macondo well blowout and oil spill. The site is in Mississippi Canyon 

Block 294, 11 km (7 mi) southwest of the spill location. The site includes hard substrate supporting coral 

in an area approximately 10 x 12 m (33 x 39 ft) (White et al., 2012). The published results document 

damage to the coral community. Forty-three coral colonies were analyzed via close-up imagery: 

86 percent exhibited signs of impact; 46 percent exhibited impact to at least 50 percent of the colony; and 

23 percent of the colonies sustained impact to more than 90 percent of the colony (White et al., 2012). 

Many other associated invertebrates also exhibited signs of stress. This appears to be an exceptional case, 

since the numerous other communities investigated since the spill remained healthy (White et al., 2012). 

Some of the oil in the water column would become diluted over time, reducing transport to the seafloor 

(Vandermeulen, 1982). Concentrations of dispersed and dissolved oil in the Macondo well blowout and 

spill subsea plume were reported to be in the part per million range or less and were generally lower away 

from the water’s surface and away from the wellhead (Adcroft et al., 2010; Haddad and Murawski, 2010; 

Joint Analysis Group, 2010; Lubchenco et al., 2010). In addition, microbial degradation of the oil occurs 

in the water, rendering the oil less toxic when it contacts the seafloor (Hazen et al., 2010). However, as 

evidenced by the report of White et al. (2012), subsea plumes can still retain toxic concentrations over a 

distance of at least 11 km (7 mi). Oil in a plume can adhere to other particles and precipitate to the 

seafloor, much like rainfall (Kingston et al., 1995; International Tanker Owners Pollution Federation 

Limited, 2007). Oil also would reach the seafloor through consumption by plankton, with excretion 

distributed over the seafloor (International Tanker Owners Pollution Federation Limited, 2007). These 

mechanisms would result in a wide distribution of small amounts of oil. Throughout these processes, oil 

would be biodegraded from bacterial action, which would continue on the seafloor, resulting in scattered 

microhabitats with an enriched carbon environment (Hazen et al., 2010).

A sustained spill may result in elevated exposure concentrations to live bottom features if a subsea oil 

plume contacts them directly. Dispersed oil is mixed with water, and its movement is then dictated by 

water currents and the physical, chemical, and biological degradation pathways. BOEM’s policy (refer to 

NTL 2009-G39) prevents wells from being placed immediately adjacent to sensitive communities; 

however, in the event of a seafloor blowout, some oil could be carried to live bottom communities by 

subsea plumes. Impacts may include reduced recruitment success, reduced growth, and reduced 

biological cover as a result of impaired recruitment. Concentrated oil plumes reaching live bottom 

communities could cause oiling of organisms, resulting in the death of entire populations on localized 

sensitive habitats. The longer the oil remains suspended in the water column the more dispersed, less 

concentrated, and more degraded it would become. Depending on how long oil remained suspended in 

the water column, it may be thoroughly degraded by biological action before contacting the seafloor 

(Hazen et al., 2010; Valentine et al., 2010). Biodegradation rates in cold, deepwater environments are not 

well understood at this time. In general, the potential impacts to deepwater live bottom communities 

would be localized due to the directional movement of oil plumes by the water currents and because the 

sensitive habitats have a scattered, patchy distribution. While a few patch habitats may be affected, the 

Gulfwide ecosystem of deepwater live bottom communities would be expected to suffer no significant 

effects.

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 
Catastrophic Spill Event Analysis B-49

buried. Based on stipulations as described in NTL 2009-G40, a well should be far enough away from 

sensitive live bottom communities to prevent extruded drilling muds from smothering them.

Phase 3—Onshore Contact

The third phase of a catastrophic blowout focuses on the approach of oil to the shoreline. This 

involves the possible oiling of coastal resources including beaches, wetlands, SAV and seagrasses, the 

shallow seafloor, and any resources drifting in the water column. Response efforts can produce additional 

serious impacts. There would be no adverse impacts to nonchemosynthetic benthic communities in deep 

water as a result of the events and the potential impact-producing factors that could occur throughout 

Phase 3 of a catastrophic spill because the communities are located offshore in deep water (>300 m; 

610 ft). 

Phase 4—Post-Spill, Long-Term Recovery and Response

The final phase of a catastrophic blowout is the long-term response of the ecosystem and its recovery. 

Both the natural rate of recovery and the persistence of oil in natural habitats over time determine what 

long-term effects may occur. Contaminants degrade over time, but they may become sequestered as inert 

forms (e.g., buried in sediment) until disturbed and re-activated, producing renewed impacts.

Although deepwater coral and other live bottom communities often live in close association with 

hydrocarbon seeps (since the carbonate substrate is precipitated by chemosynthetic communities), this 

does not mean they are necessarily tolerant to the effects of oil contamination. Natural seepage is very 

constant and at very low rates as compared with the potential volume of oil released from a catastrophic 

event (blowout or pipeline rupture). In addition, live bottom organisms, such as Lophelia pertusa, inhabit 

areas around the perimeter of seeps and sites where hydrocarbon seepage has reduced its flow or stopped. 

Typical Gulf of Mexico oil is light and floats rapidly to the surface rather than being carried horizontally 

across benthic communities by water currents (Johansen et al., 2001; MacDonald et al., 1995; Trudel 

et al., 2001). So, although deepwater live bottom communities are found near oil seeps, they are not 

typically exposed to concentrated oil.

If oil is ejected under high pressure or dispersants are applied at the source near the seafloor, oil 

would mix into the water column, be carried by underwater currents, and eventually contact the seafloor 

in some form, either concentrated (near the source) or dispersed and decayed (farther from the source). 

The oil could then impact patches of live bottom community habitat in its path. The farther the dispersed 

oil travels, the more diluted it would become as it mixes with surrounding water. Sensitive live bottom 

communities located at more than 610 m (2,000 ft) away from a blowout could experience minor impacts 

from suspended sediments that travel with currents, although the sediment concentration would be diluted 

with distance from the well.

There have been no experiments showing the response of deepwater corals to oil exposure. 

Experiments with shallow tropical corals indicate that corals have a high tolerance to oil exposure. The 

mucus layers on coral resist penetration of oil and slough off the contaminant. Longer exposure times and 

areas of tissue where oil adheres to the coral are more likely to result in tissue damage and death of 

polyps. Corals with branching growth forms appear to be more susceptible to damage from oil exposure 

(Shigenaka, 2001). The most common deepwater coral, Lophelia pertusa, is a branching species. Tests 

with shallow tropical gorgonians indicate relatively low toxic effects to the coral (Cohen et al., 1977), 

suggesting deepwater gorgonians may have a similar response. Depending on the level of exposure, the 

response of deepwater coral to oil from a catastrophic spill would vary. Exposure to widely dispersed oil 

adhering to organic detritus and partially degraded by bacteria may be expected to result in little effect. 

Direct contact with plumes of relatively fresh dispersed oil droplets in the vicinity of the incident could 

cause the death of affected coral polyps through exposure and potential feeding on oil droplets by polyps. 

Median levels of exposure to dispersed oil in a partly degraded condition may result in effects similar to 

those of shallow tropical corals, with often no discernible effects other than temporary contraction and 

some sloughing. The health of corals may be degraded by the necessary expenditure of energy as the 

corals respond to oiling (Shigenaka, 2001). Communities exposed to more concentrated oil may 

experience detrimental effects, including death of affected organisms, tissue damage, lack of growth, 

interruption of reproductive cycles, and loss of gametes. Many invertebrates associated with deepwater 

coral communities, particularly the crustaceans, would likely be more susceptible to damage from oil 
B-50 Central Planning Area Lease Sales 235, 241, and 247 EIS

exposure. The recolonization of severely damaged or destroyed communities could take years or decades. 

Burial of hard substrate could permanently prevent recovery. However, because of the scarcity of 

deepwater hard bottoms, their comparatively low surface area, and the distancing requirements set by 

BOEM in NTL 2009-G40, it is unlikely that a sensitive habitat would be located adjacent to a seafloor 

blowout or that concentrated oil would contact the site.

A catastrophic spill combined with the application of dispersant has the potential to cause devastating 

effects on local patches of habitat in the path of subsea plumes where they physically contact the seafloor. 

Sublethal effects are possible for communities that receive a lower level of impact. Examples of these 

effects could include temporary lack of feeding, expenditure of energy to remove the oil, loss of gametes 

and reproductive delays, and loss of tissue mass. Oil plumes that remain in the water column for longer 

periods would disperse and decay, having only minimal effect. Depending on how long it remains in the 

water column, oil may be thoroughly degraded by biological action before contacting the seafloor. Water 

currents can carry a plume to contact the seafloor directly, but a more likely scenario would be for oil to

adhere to other particles and precipitate to the seafloor, much like rainfall (Kingston et al., 1995; 

International Tanker Owners Pollution Federation Limited, 2007). Oil also would reach the seafloor 

through consumption by plankton with excretion distributed over the seafloor (International Tanker 

Owners Pollution Federation Limited, 2007). These mechanisms would result in a wide distribution of 

small amounts of oil (or oil by-products). This oil would be in the process of biodegradation from 

bacterial action, which would continue on the seafloor, resulting in scattered microhabitats with an 

enriched carbon environment (Hazen et al., 2010). Habitats directly under the path of the oil plume as it 

disperses and “rains” down to the seafloor may experience minor effects, but since the oil would be 

deposited in a widely scattered and decayed state, little effect is anticipated.

Overall Summary and Conclusion (Phases 1-4)

Nonchemosynthetic communities would potentially be subject to detrimental effects from a

catastrophic seafloor blowout. Sediment and oiled sediment from the initial event (Phase 1) are not likely 

to reach sensitive live bottom communities in heavy amounts because of requirements described in NTL 

2009-G40. Fine sediment from a blowout may reach the location of sensitive habitats, producing 

sublethal effects. The initial accident could result in the drilling rig and equipment falling on a sensitive 

seafloor habitat if the structure travels more than 610 m (2,000 ft) from the well site.

The ongoing spill event (Phase 2) would have the most effect on nonchemosynthetic communities. 

Deepwater live bottom communities are at risk from subsea oil plumes that could directly contact 

localized patches of sensitive habitat. Oil plumes reaching live bottom communities could cause oiling of 

organisms, resulting in the death of entire populations on localized sensitive habitats. However, the 

potential impacts would be localized due to the directional movement of oil plumes by the water currents 

and because the sensitive habitats have a scattered, patchy distribution. The more likely result would be 

exposure to widely dispersed, biodegraded particles that “rain” down from a passing oil plume. While a 

few patch habitats may be affected, the gulf-wide ecosystem of live bottom communities would be 

expected to suffer no significant effects.

As oil approaches shore (Phase 3), there would be no adverse impacts to nonchemosynthetic 

communities because the communities are located offshore in deep water (>300 m; 610 ft).

The recovery of nonchemosynthetic communities (Phase 4) depends on the severity of initial impacts. 

A catastrophic spill combined with the application of dispersant has the potential to cause devastating 

effects on local patches of sensitive habitat in the path of subsea plumes where they physically contact the 

seafloor. The recolonization of severely damaged or destroyed communities could take years or decades. 

Burial of hard substrate could permanently prevent recovery. Sublethal effects are possible for 

communities that receive a lower level of impact. Examples of these effects could include temporary lack 

of feeding, expenditure of energy to remove the oil, loss of gametes and reproductive delays, and loss of 

tissue mass. However, most live bottom community habitats are expected to experience no impacts from 

a catastrophic seafloor blowout because of the directional movement of oil plumes by the water currents 

and because the sensitive habitats have a scattered, patchy distribution.
Catastrophic Spill Event Analysis B-51

B.3.1.11. Soft Bottom Benthic Communities

The seafloor on the continental shelf in the Gulf of Mexico consists primarily of muddy to sandy 

sediments. Benthic organisms found on the seafloor include infauna (animals that live in the substrate, 

including mostly burrowing worms, crustaceans, and mollusks) and epifauna (animals that live on or are 

attached to the substrate; mostly crustaceans, as well as echinoderms, mollusks, hydroids, sponges, soft 

and hard corals, and demersal fishes). Infauna is comprised of meiofauna, small organisms (63-500 μm) 

that live among the grains of sediment; and macroinfauna, slightly larger organisms (>0.5 mm; 0.02 in) 

that live in the sediment (Dames and Moore, Inc., 1979). Shrimp and demersal fish are closely associated 

with the benthic community. The most abundant organisms on the continental shelf are the depositfeeding polychaetes. The slope and deep sea consist of vast areas of primarily fine sediments that support 

benthic communities with lower densities and biomass but higher diversity than the continental shelf 

(Rowe and Kennicutt, 2001).

Phase 1—Initial Event

A blowout from an oil well could result in a catastrophic spill event. A catastrophic blowout would 

result in released oil rapidly rising to the sea surface because all known reserves in the GOM have 

specific gravity characteristics that would preclude oil from sinking immediately after release at a 

blowout site. The oil would surface almost directly over the source location. However, if the oil is 

ejected under high pressure, micro-droplets of oil may form and become entrained in the water column 

(Boehm and Fiest, 1982; Adcroft et al., 2010). The upward movement of the oil may be reduced if 

methane mixed with the oil is dissolved into the water column, reducing the oil’s buoyancy (Adcroft 

et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by vigorous 

turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the water column, 

creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). Dispersed oil in the water 

column begins to biodegrade and may flocculate with particulate matter, promoting sinking of the 

particles. Subsea plumes or sinking oil on particulates may contact portions of the seafloor.

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. Some fine sediment could travel up to a few 

thousand meters before redeposition, negatively impacting a localized area of benthic communities. The 

localized seafloor habitat around which a seafloor blowout occurs would be impacted by suspended and 

redeposited sediment.

A catastrophic blowout that occurs above the seabed (at the rig, along the riser between the seafloor 

and sea surface, or through leak paths on the BOP/wellhead) would not disturb the sediment.

The use of subsea dispersants would increase the exposure of offshore benthic habitats to dispersed 

oil droplets in the water column, as well as the chemicals used in the dispersants. The use of subsea 

dispersants is not likely to occur for seafloor blowouts outside the well casing.

Impacts to Soft Bottom Benthic Communities

Impacts that occur to benthic organisms as a result of a blowout would depend on the type of blowout 

and their distance from the blowout. Also, if the blowout were to occur beneath the seabed, soft sediment 

habitat would be destroyed by the formation of a crater, and the suspension and subsequent deposition of 

disturbed sediment would smother localized areas of benthic communities. A blowout that occurs outside 

the well casing can rapidly deposit 30 cm (12 in) or more of sediment within a few hundred meters and 

may smother much of the soft bottom community in a localized area. Benthic communities exposed to 

large amounts of resuspended and deposited sediments following a catastrophic, subsurface blowout 

could be subject to smothering, sediment suffocation, and exposure to resuspended toxic contaminants. 

Impacts to organisms as a result of sedimentation would vary based on species tolerance, degree of 

sedimentation, length of exposure, burial depth, and vertical migration ability through sediment.

A portion or the entire rig may sink to the seafloor as a result of a blowout. The benthic features and 

communities upon which the rig settles would be destroyed or smothered. A settling rig may suspend 

sediments, which may smother nearby benthic communities. The habitats beneath the rig may be 

permanently lost; however, the rig itself may become an artificial reef upon which epibenthic organisms 

may settle. The surrounding benthic communities that were smothered by sediment would repopulate 
B-52 Central Planning Area Lease Sales 235, 241, and 247 EIS

from nearby stocks through spawning recruitment and immigration if the hard substrate upon which they 

live was not physically destroyed.

Phase 2—Offshore Spill

A spill from a shallow-water blowout could impact benthic communities on the continental shelf. 

The scenario (Table B-4) for a catastrophic spill on the continental shelf is assumed to last 2-5 months 

and to release 30,000 bbl per day. A total volume of 0.9-3.0 MMbbl of South Louisiana midrange 

paraffinic sweet crude oil could be released, which would float (APIo >10). An anticipated 35,000 bbl of 

dispersant may be applied to the surface waters.

A spill from a deepwater blowout could also impact shelf communities and deepwater communities. 

The scenario (Table B-4) for a catastrophic spill in deep water is assumed to last 4-6 months and to 

release 30,000-60,000 bbl per day. A total volume of 2.7-7.2 MMbbl of South Louisiana midrange 

paraffinic sweet crude oil could be released, which would float (APIo >10). Oil properties may change as 

it passes up the well and through the water column, and it may become emulsified. An anticipated 

33,000 bbl of dispersant may be applied to the surface waters and 16,500 bbl may be applied subsea. 

Weathering and dilution of the oil would also occur as it travels from its launch point. It is unlikely that a 

subsurface plume from a deepwater blowout would impact shelf communities. The oil is anticipated to 

remain in deep water and be directed by water currents in the deep water. These currents do not typically 

transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 2008).

Impacts to Soft Bottom Benthic Communities

Impacts from Surface Oil

Surface oil slicks can spread over a large area; however, the majority of the slick is comprised of a 

very thin surface layer of oil moved by winds and currents (Lewis and Aurand, 1997). The potential of 

surface oil slicks to affect benthic habitats is limited by its ability to mix into the water column. Soft 

bottom benthic communities below 10-m (33-ft) water depth are protected from surface oil because of its 

lack of ability to mix with water (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 

2002). Benthic organisms would not become physically coated or smothered by surface oil. However, if 

this surface oil makes its way into the water column through physical mixing, the use of dispersants, or 

the sedimenting to particles in the water column, benthic communities may be impacted. These scenarios 

are discussed in later sections.

Disturbance of the sea surface by storms can mix surface oil into the water column, but the effects are 

generally limited to the upper 10-20 m (33-66 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich 

and Chan, 2002). Therefore, soft bottom benthic communities located in shallow water have the potential 

to be fouled by oil that is floating on shallow water and mixes to the depth of the seafloor. Nearshore oil 

deposits that occur in sheltered areas, such as bays, may remain in the sediment and impact organisms for 

long periods. Oil in nearshore sediments was found in high concentrations 8 years following the Exxon 

Valdez spill (Dean and Jewett, 2001). Benthic communities located in deeper water would not be 

impacted by oil physically mixed into the water column. However, if dispersants are used, they would 

enable oil to mix into the water column and possibly impact organisms in deeper water. Dispersants are 

discussed later in this chapter. Further detail on this catastrophic OSRA run is contained in Appendix C. 

Impacts from Subsurface Oil

The presence of a subsurface oil plume on the continental shelf from a shallow-water blowout may 

affect soft bottom benthic communities. A majority of the oil released is expected to rise rapidly to the 

sea surface above the launch point because of the specific gravity characteristics of the oil reserves in the 

GOM, thus not directly sinking to the seafloor and smothering benthic communities. If the oil is ejected 

under high pressure, oil droplets may become entrained in the water column (Boehm and Fiest, 1982; 

Adcroft et al., 2010). The upward movement of the oil may be reduced if methane mixed with the oil is 

dissolved into the water column, reducing the oil’s buoyancy (Adcroft et al., 2010). Large oil droplets 

would rise to the sea surface, but smaller droplets, formed by vigorous turbulence in the plume or the 

injection of dispersants, may remain neutrally buoyant in the water column, creating a subsurface plume 

(Adcroft et al., 2010; Joint Analysis Group, 2010). Dispersed oil in the water column begins to 
Catastrophic Spill Event Analysis B-53

biodegrade and may flocculate with particulate matter, promoting sinking of the particles. Subsurface 

plumes generated by high-pressure dissolution of oil may come in contact with portions of the seafloor as 

it travels from the source. A sustained spill would continuously create surface slicks and possibly 

subsurface plumes. Some of the oil in the water column will become diluted or evaporated over time, 

reducing any localized transport to the seafloor (Vandermeulen, 1982). In addition, microbial degradation 

of the oil occurs in the water column so that the oil would be less toxic as it travels from the source 

(Hazen et al., 2010). However, a sustained spill may result in elevated exposure concentrations to benthic 

communities if the plume reaches them. The longer the spill takes to stop, the longer the exposure time 

and higher the exposure concentration may be.

Soft bottom infaunal communities that come into direct contact with oil may experience sublethal 

and/or lethal effects. The greatest effects of oil exposure would occur close to the well and impacts 

would decrease with distance. A subsurface plume that contacts the seafloor may result in acute toxicity. 

The water accommodated fraction (WAF) or water soluble fraction (WSF) of oil that dissolves in water 

may be the most toxic to organisms, especially larvae and embryos in the water column or at the water 

sediment interface. Lethal effects for marine invertebrates have been reported at exposures between 

0.10 ppm to 100 ppm WSF of oil (Suchanek, 1993). The WSF of petroleum hydrocarbons was reportedly 

highly toxic to the embryos of oysters and sea urchins, while sediment containing weathered fuel was not 

toxic to the same species (Beiras and Saco-Álvarez, 2006). Quahog clam embryos and larvae also 

experienced toxicity and deformation of several different crude oils at WSF concentrations between 

0.10 ppm and 10 ppm (Byrne and Calder, 1977). An experiment indicated that the WSF of No. 2 fuel oil 

at a concentration of 5 ppm disrupted the cellular development of 270 out of 300 test organisms within 

3 hours of exposure (Byrne, 1989). After 48 hours exposure, all of the test organisms died and the 

48-hour LC50 (lethal concentration for 50% of the test population) was calculated to be 0.59 ppm (Byrne, 

1989). Another experiment indicated that a WSF of 0.6 ppm and greater of No. 2 fuel oil depressed 

respiration, reduced mobility of sperm, interfered with cell fertilization and embryonic cleavage, and 

retarded larval development of sand dollar eggs (Nicol et al., 1977). Experiments that exposed sea urchin 

embryos to 10-30 ppm WSF of diesel oil for 15-45 days resulted in defective embryonic development and 

nonviable offspring (Vashchenko, 1980). Therefore, any dissolved petroleum hydrocarbon constituents 

that reach larval benthic organisms may cause acute toxicity and other developmental effects to this life 

stage. The WAF and WSF, however, should be considered “worst-case scenario” values as they are 

based on a closed system at equilibrium with the contaminant and, due to its size and complexity, the 

GOM will not reach equilibrium with released oil.

Oil in the water column may impact pelagic eggs and larvae of invertebrates. Toxicity tests indicated 

that eggs of many species were killed by diesel oil in seawater, and in general, the smaller eggs died 

earlier (Chia, 1973). Bivalve fertilization and sperm fertility were depressed with exposure to crude oil 

(Renzoni, 1975). The WSF of crude oil was also highly toxic to gametes, embryos, and larvae of bivalves 

(Renzoni, 1975). Oil concentrations of 0.1 and 1 ppm caused a decrease in fertilization, development of 

embryos, survival or larvae, and larval growth in the bivalves Crassostrea virginica and Mulinia lateralis

(Renzoni, 1975). Another experiment, however, calculated the LC50 for a 6-hour exposure of the 

gametes, eggs, and larvae of three bivalves (Crassostrea angulata, Crassostrea gigas, and Mytilus 

galloprovincialis) to be 1,000 ppm oil and 1,000 ppm oil plus dispersant (Renzoni, 1973). Toxicity varies 

widely among species and oil types.

Sublethal responses of marine invertebrates may result in population level changes (Suchanek, 1993). 

Such sublethal responses may occur at concentrations as low as 1-10 ppb (Hyland and Schneider, 1976). 

Sublethal impacts may include reduced feeding rates, reduced ability to detect food, ciliary inhibition, 

reduced movement, decreased aggression, and altered respiration (Suchanek, 1993).

The farther a subsea plume travels, the more physical and biological changes occur to the oil before it 

reaches benthic organisms. Oil would become diluted as it physically mixes with the surrounding water, 

and significant evaporation occurs from surface slicks. The most toxic compounds of oil are lost within 

the first 24 hours of a spill, leaving the heavier, less toxic compounds in the system (Ganning et al., 

1984). An even greater component of the lighter fuel oils dissipates through evaporation. Water currents 

could carry a plume to contact the seafloor directly, but a likely scenario would be for the oil to adhere to 

other particles and precipitate to the seafloor, much like rainfall (International Tanker Owners Pollution 

Federation Limited, 2002; Kingston et al., 1995). Oil also would reach the seafloor through consumption 

by plankton, with excretion distributed over the seafloor (International Tanker Owners Pollution 

Federation Limited, 2002). The longer and farther a subsea plume travels in the sea, the more dilute the 
B-54 Central Planning Area Lease Sales 235, 241, and 247 EIS

oil would be (Vandermeulen, 1982; Tkalich and Chan, 2002). In addition, microbial degradation of the 

oil occurs in the water column, reducing toxicity (Hazen et al., 2010; McAuliffe et al., 1981b). The oil 

would move in the direction of prevailing currents (S.L. Ross Environmental Research Ltd., 1997) and, 

although the oil would weather with the distance it travels, low levels of oil transported in subsea plumes 

would impact benthic communities. These mechanisms would result in a wide distribution of small 

amounts of oil. This oil would be in the process of biodegradation from bacterial action, which would 

continue on the seafloor, resulting in scattered microhabitats with an enriched carbon environment (Hazen 

et al., 2010).

Localized areas of lethal effects would be recolonized by populations from neighboring soft bottom

substrate once the oil in the sediment has been sufficiently reduced to a level able to support marine life 

(Sanders et al., 1980; Lu and Wu, 2006; Ganning et al., 1984; Gómez Gesteira and Dauvin, 2000; Dean 

and Jewett, 2001). This initial recolonization process may be fairly rapid, but full recovery may take up 

to 10 years depending on the species present, substrate in the area, toxicity of oil spilled, concentration 

and dispersion of oil spilled, and other localized environmental factors that may affect recruitment 

(Kingston et al., 1995; Gesteira and Dauvin, 2000; Sanders et al., 1980; Conan, 1982). Opportunistic 

species would take advantage of the barren sediment, repopulating impacted areas first. These species 

may occur within the first recruitment cycle of the surrounding populations or from species immigration 

from surrounding stocks and may maintain a stronghold in the area until community succession begins 

(Rhodes and Germano, 1982; Sanders et al., 1980).

It is unlikely that a subsurface plume from a deepwater blowout would impact shelf communities. 

The oil is anticipated to remain in deep water and be directed by water currents in the deep water. These 

currents do not typically transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 

2008). However, the impacts to deepwater soft bottom benthic communities as a result of a blowout 

would similar to those on the continental shelf.

Impacts from Dispersed Oil

If dispersants are used at the sea surface, oil may mix into the water column, and if they are applied 

subsea, dispersed oil can travel with currents and contact the seafloor. Chemically dispersed oil from a 

surface slick is not anticipated to result in lethal exposures to organisms on the seafloor. The chemical 

dispersion of oil may increase the weathering process and allow surface oil to be diluted by greater 

amounts of water. Reports on dispersant usage on surface plumes indicate that a majority of the dispersed 

oil remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (6 ft) 

(McAuliffe et al., 1981a). Dispersant usage also reduces the oil’s ability to stick to particles in the water 

column, minimizing oiled sediments from traveling to the seafloor (McAuliffe et al., 1981a). If applied, 

subsea benthic communities near the source could be exposed to dispersed oil that is concentrated enough 

to harm the benthic community. If the oil remains suspended for a longer period of time, it would be 

more dispersed and less concentrated. There is very little information on the behavior of subsea 

dispersants.

Dispersed oil used at the sea surface reaching the benthic communities in the Gulf of Mexico would 

be expected to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a). Such concentrations 

would not be life threatening to larval or adult stages on the seafloor based on experiments conducted 

with benthic and pelagic species (Scarlett et al., 2005; Hemmer et al., 2010; George-Ares and Clark, 

2000). Any dispersed oil in the water column that comes in contact with benthic communities may evoke

short-term negative responses by the organisms (Scarlett et al., 2005). Sublethal responses may include 

reduced feeding rate, erratic movement, and tentacle retraction (Scarlett et al., 2005). In addition, 

although dispersants were detected in waters off Louisiana after the Macondo well blowout and spill, they 

were below USEPA benchmarks of chronic toxicity (OSAT, 2010). The rapid dilution of dispersants in 

the water column and lack of transport to the seafloor was also reported by OSAT (2010) where no 

dispersants were detected in sediment on the Gulf floor following the Macondo well blowout and spill. 

Impacts from Oil Adhering to Sediments

Oiled sediment that settles to the seafloor may affect organisms upon which it settles. The greatest 

impacts would be closest to the well where organisms may become smothered by particles and exposed to 

hydrocarbons. High concentrations of suspended sediment in the water column may lend to large 
Catastrophic Spill Event Analysis B-55

quantities of oiled sediment (Moore, 1976). Deposition of oiled sediment is anticipated to begin 

occurring within days or weeks of the spill and may be fairly deep near the source (Ganning et al., 1984; 

Gómez Gesteira and Dauvin, 2000). Oily sand layers were reported to be 10 cm (4 in) deep on the 

seafloor near the Amoco Cadiz spill (Gómez Gesteira and Dauvin, 2000). Acute toxicity may occur near 

the spill, eliminating benthic communities.

Much of the oil released from a blowout would rise to the sea surface, therefore dispersing the 

released oil before it makes its way back to the seafloor through flocculation, by deposition from 

organisms that pass it through their systems with food, and by adhering to sinking particles in the water 

column. In addition, small droplets of oil that are entrained in the water column for extended periods of 

time may migrate a great distance from their point of release and may attach to suspended particles in the 

water column and later be deposited on the seafloor (McAuliffe et al., 1975). The majority of organisms 

exposed to oiled sediment are anticipated to experience low-level concentrations because as the oiled 

sediments settle to the seafloor they are widely dispersed. Impacts may include reduced recruitment 

success, reduced growth, and altered community composition as a result of impaired recruitment.

Impacts from Oil-Spill-Response Activity

Continued localized disturbance of soft bottom communities may occur during oil-spill response 

efforts. Anchors used to set booms to contain oil or vessel anchors in decontamination zones may affect 

infaunal communities in the response activity zone. Infaunal communities may be altered in the anchor 

scar, and deposition of suspended sediment may result from the setting and resetting of anchors. The 

disturbed benthic community should begin to repopulate from the surrounding communities during their 

next recruitment event and through immigration of organisms from surrounding stocks. Any 

decontamination activities, such as cleaning vessel hulls of oil, may also contaminate the sediments of the 

decontamination zone, as some oil may settle to the seabed, impacting the underlying benthic community.

If a blowout occurs at the seafloor, drilling muds (primarily barite) may be pumped into a well in 

order to “kill” it. If a kill is not successful, the mud (possibly tens of thousands of barrels) may be forced 

out of the well and deposited on the seafloor near the well site. Any organisms beneath heavy layers of 

the extruded drilling mud would be buried. Base fluids of drilling muds are designed to be low in toxicity 

and biodegradable in offshore marine sediments (Neff et al., 2000). However, as bacteria and fungi break 

down the drilling fluids, the sediments may temporarily become anoxic (Neff et al., 2000). Benthic 

macrofaunal recovery would occur when drilling mud concentrations are reduced to levels that enable the 

sediment to become re-oxygenated (Neff et al., 2000). Complete community recovery from drilling mud 

exposure may take 3-5 years, although microbial degradation of drilling fluids, followed by an influx of 

tolerant opportunistic species, is anticipated to begin almost immediately (Neff et al., 2000). In addition, 

the extruded mud may bury hydrocarbons from the well, making them a hazard to the infaunal species 

and difficult to remove.

Phase 3—Onshore Contact

There would likely be no additional adverse impacts to soft bottom benthic communities as a result of 

events and the potential impact producing factors that could occur throughout Phase 3 of a catastrophic 

spill because these soft bottom benthic communities are located below the water line.

Phase 4—Post-Spill, Long-Term Recovery and Response

Benthic Habitats

In situations where soft bottom infaunal communities are negatively impacted, recolonization by 

populations from neighboring soft bottom substrate would be expected over a relatively short period. 

Recolonization would begin with recruitment and immigration of opportunistic species from surrounding

stocks. More complex communities would follow with time. Repopulation could take longer for areas 

affected by direct oil contact in higher concentrations.

Many of the organisms on soft bottoms live within the sediment and have the ability to migrate 

upward in response to burial by sedimentation. A blowout that occurs outside the well casing can rapidly 

deposit 30 cm (12 in) or more of sediment within a few hundred meters and may smother much of the soft 

bottom community in a localized area. In situations where soft bottom infaunal communities are 
B-56 Central Planning Area Lease Sales 235, 241, and 247 EIS

negatively impacted, recolonization by populations from neighboring soft bottom substrate would be 

expected over a relatively short period of time for all size ranges of organisms, in a matter of days for 

bacteria, and probably less than 1 year for most macrofauna and megafauna species. Recolonization 

could take longer for areas affected by direct contact of concentrated oil. Initial repopulation from nearby 

stocks of pioneering species, such as tube-dwelling polychaetes or oligochaetes, may begin with the next 

recruitment event (Rhodes and Germano, 1982). Full recovery would follow as later stages of 

successional communities overtake the pioneering species (Rhodes and Germano, 1982). The time it 

takes to reach a climax community may vary depending on the species and degree of impact. Full benthic 

community recovery may take years to decades if the benthic habitat is heavily oiled (Gómez Gesteira 

and Dauvin, 2000; Sanders et al., 1980; Conan, 1982). A slow recovery rate would result in a community 

with reduced biological diversity and possibly a lesser food value for predatory species.

Localized areas of lethal effects would be recolonized by populations from neighboring soft bottom

substrate once the oil in the sediment has been sufficiently reduced to a level able to support marine life 

(Sanders et al., 1980; Lu and Wu, 2006; Ganning et al., 1984; Gómez Gesteira and Dauvin, 2000; Dean 

and Jewett, 2001). This initial recolonization process may be fairly rapid, but full recovery may take up 

to 10 years depending on the species present, substrate in the area, toxicity of oil spilled, concentration 

and dispersion of oil spilled, and other localized environmental factors that may affect recruitment 

(Kingston et al., 1995; Gómez Gesteira and Dauvin, 2000; Sanders et al., 1980; Conan, 1982). 

Opportunistic species would take advantage of the barren sediment, repopulating impacted areas first. 

These species may occur within the first recruitment cycle of the surrounding populations or from species 

immigration from surrounding stocks and may maintain a stronghold in the area until community 

succession begins (Rhodes and Germano, 1982; Sanders et al., 1980).

Overall Summary and Conclusion (Phases 1-4)

A catastrophic blowout and spill would have the greatest impact on the soft bottom benthic 

communities in the immediate vicinity of the spill. Turbidity, sedimentation, and oiling would be 

heaviest closest to the source, and decrease with distance from the source. Complete loss of benthic 

populations may occur with heavy sedimentation and oil deposition. Farther from the well, a less thick 

layer of sediment would be deposited and oil would be dispersed from the source, resulting in sublethal 

impacts. The recovery of benthic populations would begin with recruitment from surrounding areas fairly 

rapidly.

B.3.1.12. Marine Mammals

Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout event. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and 

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1 or 2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. 

Potential impacts reflect the explosion, subsequent fire for 1-30 days, and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well.

Depending on the type of blowout, the pressure waves and noise generated by the eruption of gases 

and fluids would likely be significant enough to harass, injure, or kill marine mammals, depending on the 

proximity of the animal to the blowout. A high concentration of response vessels could result in 

harassment or displacement of individuals and could place marine mammals at a greater risk of vessel 

collisions, which would likely cause fatal injuries.

The scenarios for each phase, including cleanup methods, can be found in Table B-4. 
Catastrophic Spill Event Analysis B-57

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. Potential 

impacts reflect spill and response in Federal and State offshore waters. Season and temperature variations 

can result in different resource impacts due to variations in oil persistence and oil and dispersant toxicity 

and because of differences in potential exposure of the resources throughout various life cycle stages.

An oil spill and related spill-response activities can impact marine mammals that come into contact 

with oil and remediation efforts. The marine mammals’ exposure to hydrocarbons persisting in the sea 

may result in sublethal impacts (e.g., decreased health, reproductive fitness, longevity, and increased 

vulnerability to disease), some soft tissue irritation, respiratory stress from inhalation of toxic fumes, food 

reduction or contamination, direct ingestion of oil and/or tar, and temporary displacement from preferred 

habitats or migration routes. More detail on the potential range of effects to marine mammals from 

contact with spilled oil can be found in Geraci and St. Aubin (1990). The best available information does 

not provide a complete understanding of the effects of the spilled oil and active response/cleanup 

activities on marine mammals. For example, it is expected that the large amount of chemical dispersants

being used on the oil may act as an irritant on the marine mammals’ tissues and sensitive membranes.

The increased human presence after an oil spill (e.g., vessels) would likely add to changes in behavior 

and/or distribution, thereby potentially stressing marine mammals further and perhaps making them more 

vulnerable to various physiologic and toxic effects. In addition, the large number of response vessels 

could place marine mammals at a greater risk of vessel collisions, which could cause fatal injuries.

The potential biological removal (PBR) level is defined by the Marine Mammal Protection Act as the 

maximum number of animals, not including natural mortalities that may be removed from a marine 

mammal stock while allowing that stock to reach or maintain its optimum sustainable population. 

However, in the Gulf of Mexico, many marine mammal species have unknown PBR’s or PBR’s with 

outdated abundance estimates, which are considered undetermined. The biological significance of any

injury or mortality would depend, in part, on the size and reproductive rates of the affected stocks, as well 

as the number, age, and size of the marine mammals affected.

The Deepwater Horizon explosion, oil spill, and response in Mississippi Canyon Block 252 

(including use of dispersants) have impacted marine mammals that have come into contact with oil and 

remediation efforts. According to the “Dolphins and Whales of the Gulf of Mexico Oil Spill” website, 

within the designated Deepwater Horizon explosion, oil spill, and response area, 171 marine mammals 

(89% of which were deceased) were reported. This includes 155 bottlenose dolphins, 2 Kogia spp., 

2 melon-headed whales, 6 spinner dolphins, 2 sperm whales, and 4 unknown species (USDOC, NMFS, 

2011b). All marine mammals collected either alive or dead were found east of the Louisiana/Texas 

border through Apalachicola, Florida. The highest concentration of strandings has occurred off eastern 

Louisiana, Mississippi, and Alabama, with a significantly lesser number off western Louisiana and 

western Florida (USDOC, NMFS, 2011b). Due to known low-detection rates of carcasses, it is possible 

that the number of deaths of marine mammals is underestimated (Williams et al., 2011). It is also 

important to note that evaluations have not yet confirmed the cause of death, and it is possible that many, 

some, or no carcasses collected were related to the Deepwater Horizon explosion, oil spill, and response. 

These stranding numbers are significantly greater than reported in past years; though it should be further 

noted that stranding coverage (i.e., effort in collecting strategies) has increased considerably due to the 

Deepwater Horizon explosion, oil spill, and response. Further detail on this catastrophic OSRA run is 

contained in Appendix C. 

Phase 3—Onshore Contact

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response and oil initially reaching the shoreline during the spill event or while the oil still persists in the 

offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. Re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 
B-58 Central Planning Area Lease Sales 235, 241, and 247 EIS

contacted shore. Potential impacts reflect the spill and response in very shallow coastal waters and once 

along the shoreline. Season and temperature variations can result in different resource impacts due to 

variations in oil persistence and oil and dispersant toxicity and because of differences in potential 

exposure of the resources throughout various life cycle stages.

A high-volume oil spill lasting 90 days could directly impact over 22 species of marine mammals. As 

a spill enters coastal waters, manatees and coastal and estuarine dolphins would be the most likely to be 

affected.

Manatees primarily inhabit open coastal (shallow nearshore) areas and estuaries, and they are also 

found far up in freshwater tributaries. Florida manatees have been divided into four distinct regional 

management units: the Atlantic Coast Unit that occupies the east coast of Florida, including the Florida 

Keys and the lower St. Johns River north of Palatka, Florida; the Southwest Unit that occurs from Pasco 

County, Florida, south to Whitewater Bay in Monroe County, Florida; the Upper St. Johns River Unit that 

occurs in the river south of Palatka, Florida; and the Northwest Unit that occupies the Florida Panhandle 

south to Hernando County, Florida (Waring et al., 2012). Manatees from the Northwest Unit are more 

likely to be seen in the northern GOM, and they can be found as far west as Texas; however, most 

sightings are in the eastern GOM (Fertl et al., 2005).

During warmer months (June to September), manatees are common along the Gulf Coast of Florida 

from the Everglades National Park northward to the Suwannee River in northwestern Florida. Although 

manatees are less common farther westward, manatee sightings increase during the warmer summer 

months. Winter habitat use is primarily influenced by water temperature as animals congregate at natural 

(springs) and/or artificial (power plant outflows) warm water sources (Alves-Stanley et al., 2010). 

Manatees are infrequently found as far west as Texas (Powell and Rathbun, 1984; Rathbun et al., 1990; 

Schiro et al., 1998). If a catastrophic oil spill reached the Florida coast when manatees were in or near 

coastal waters, the spill could have population-level effects.

It is possible that manatees could occur in coastal areas where vessels traveling to and from the spill 

site could affect them. A manatee present where there is vessel traffic could be injured or killed by a 

vessel strike (Wright et al., 1995). Due to the large number of vessels responding to a catastrophic spill 

both in coastal waters and traveling through coastal waters to the offshore site, manatees would have an 

increased risk of collisions with boats. Vessel strikes are the primary cause of death of manatees.

The best available count of Florida manatees is 4,834 animals, based on a January 2011 aerial survey 

of warm water refuges (Florida Fish and Wildlife Conservation Commission, 2011). By November 2012, 

there were 306 manatee carcasses collected in Florida, 80 of these animals died of human causes (Florida 

Fish and Wildlife Conservation Commission, 2012). Human causes included water control structures, 

entanglement in and ingestion of marine debris, entrapment in pipes/culverts, and collisions with 

watercraft. Eight-six percent of the manatees that died of human causes were killed by watercraft 

(Florida Fish and Wildlife Conservation Commission, 2012). Therefore, if a catastrophic spill and 

response vessel traffic occurred near manatee habitats in the eastern Gulf of Mexico, population-level 

impacts could occur because the possibility exists for the number of mortalities to exceed the potential 

biological removal.

There have been no experimental studies and only a few observations suggesting that oil impacts have 

harmed any manatees (St. Aubin and Lounsbury, 1990). Types of impacts to manatees and dugongs from 

contact with oil include (1) asphyxiation because of inhalation of hydrocarbons, (2) acute poisoning 

because of contact with fresh oil, (3) lowering of tolerance to other stress because of the incorporation of 

sublethal amounts of petroleum components into body tissues, (4) nutritional stress through damage to 

food sources, and (5) inflammation or infection and difficulty eating because of oil sticking to the sensory 

hairs around their mouths (Preen, 1989, in Sadiq and McCain, 1993; Australian Maritime Safety 

Authority, 2003). For a population whose environment is already under great pressure, even a localized 

incident could be significant (St. Aubin and Lounsbury, 1990). Spilled oil might affect the quality or 

availability of aquatic vegetation, including seagrasses, upon which manatees feed.

Bottlenose dolphins were the most affected species of marine mammals from the Deepwater Horizon

explosion, oil spill, and response. According to the “Dolphins and Whales of the Gulf of Mexico Oil 

Spill” website, within the designated Deepwater Horizon explosion, oil spill, and response area, 

171 marine mammals (89% of which were deceased) were reported. This includes 155 bottlenose 

dolphins, 2 Kogia spp., 2 melon-headed whales, 6 spinner dolphins, 2 sperm whales, and 4 unknown 

species (USDOC, NMFS, 2011b). 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 
Catastrophic Spill Event Analysis B-59

Horizon explosion, oil spill, and response. Bottlenose dolphins can be found throughout coastal waters in 

the Gulf of Mexico. Like manatees, dolphins could be affected, possibly to population level, by a 

catastrophic oil spill if it reaches the coast (as well as affecting them in the open ocean), through direct 

contact, inhalation, ingestion, and stress, as well as through collisions with cleanup vessels.

Phase 4—Post-Spill, Long-Term Recovery and Response

Phase 4 focuses on long term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 

killed and cleanup activities are concluding. While it is assumed that the majority of spilled oil would be 

dissipated offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil 

has the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt 

marshes, oil may seep into the muddy bottoms. Potential impacts reflect long-term persistence of oil in 

the environment and residual and long term clean-up efforts.

Even after the spill is stopped, oilings or deaths of marine mammals would still likely occur because 

of oil and dispersants persisting in the water, past marine mammal/oil or dispersant interactions, and 

ingestion of contaminated prey. The animals’ exposure to hydrocarbons persisting in the sea may result 

in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased 

vulnerability to disease) and some soft tissue irritation, respiratory stress from inhalation of toxic fumes, 

food reduction or contamination, direct ingestion of oil and/or tar, and temporary displacement from 

preferred habitats or migration routes. A catastrophic oil spill could lead to increased mortalities, 

resulting in potential population-level effects for some species/populations (USDOC, NMFS, 2010b).

On December 13, 2010, NMFS declared an unusual mortality event (UME) for cetaceans (whales and 

dolphins) in the Gulf of Mexico. An UME is defined under the Marine Mammal Protect Act as a 

“stranding that is unexpected, involves a significant die-off of any marine mammal population, and 

demands immediate response.” Evidence of the UME was first noted by NMFS as early as February 1, 

2010, before the Macondo well blowout and spill. As of July 29, 2012, a total of 759 cetaceans 

(5% stranded alive and 95% stranded dead) have stranded since the start of the UME, with a vast majority 

of these strandings between Franklin County, Florida, and the Louisiana/Texas border. The 

759 cetaceans include 6 dolphins killed during a fish-related scientific study and 1 dolphin killed 

incidental to trawl relocation for a dredging project. More detail on the UME can be found on NMFS’s 

website (USDOC, NMFS, 2012a). In addition to investigating all other potential causes, scientists are 

investigating what role Brucella may have played in the UME, and this continues today.

On May 9, 2012, NOAA declared an UME for bottlenose dolphins in five Texas counties. The UME 

lasted from November 2011-March 2012, when 123 bottlenose dolphins stranded in Aransas, Calhoun, 

Kleberg, Galveston, and Brazoria Counties in Texas. The investigation is ongoing (USDOC, NMFS, 

2012b).

Overall Summary and Conclusion (Phases 1-4)

Accidental events related to a CPA proposed action have the potential to have adverse, but not 

significant impacts to marine mammal populations in the GOM. Accidental blowouts, oil spills, and 

spill-response activities may impact marine mammals in the GOM. Characteristics of impacts (i.e., acute 

vs. chronic impacts) depend on the magnitude, frequency, location, and date of accidents; characteristics 

of spilled oil; spill-response capabilities and timing; and various meteorological and hydrological factors.

B.3.1.13. Sea Turtles

Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout incident. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and 

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1-2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 
B-60 Central Planning Area Lease Sales 235, 241, and 247 EIS

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. 

Potential impacts reflect the explosion, subsequent fire for 1-30 days, and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well.

Five species of sea turtles are found in the waters of the Gulf of Mexico: green, leatherback, 

hawksbill, Kemp’s ridley, and loggerhead. All species are protected under the Endangered Species Act

(ESA), and all are listed as endangered except the loggerhead turtle, which is listed as threatened. 

Depending on the type of blowout, an eruption of gases and fluids may generate significant pressure 

waves and noise that may harass, injure, or kill sea turtles, depending on their proximity to the accident. 

A high concentration of response vessels could place sea turtles at a greater risk of fatal injuries from 

vessel collisions. All sea turtle species and life stages are vulnerable to the harmful effects of oil through 

direct contact or by fouling of their habitats and prey.

Further, mitigation by burning puts turtles at risk because they tend to be gathered up in the corralling 

process necessary to concentrate the oil in preparation for the burning. Trained observers should be 

required during any mitigation efforts that include burning. The scenarios for each phase, including 

cleanup methods, can be found in Table B-4. 

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. Potential 

impacts reflect spill and response in Federal and State offshore waters. Season and temperature variations 

can result in different resource impacts due to variations in oil persistence and oil and dispersant toxicity 

and because of differences in potential exposure of the resources throughout various life cycle stages.

Sea turtles are more likely to be affected by a catastrophic spill in shallow water than in deep water 

because not all sea turtles occupy a deepwater habitat. For example, Kemp’s ridley sea turtles are 

unlikely to be in water depths of 160 ft (49 m) or greater. Hawksbill sea turtles are commonly associated 

with coral reefs, ledges, caves, rocky outcrops, and high energy shoals. Green sea turtles are commonly 

found in coastal benthic feeding grounds, although they may also be found in the convergence zones of 

the open ocean. Convergence zones are areas that also may collect oil. Leatherback sea turtles are 

commonly pelagic and are the sea turtle species most likely to be affected by a deepwater oil spill. As the 

spilled oil moves toward land, additional species of sea turtles are more likely to be affected.

The Deepwater Horizon explosion, oil spill, and response in Mississippi Canyon Block (including use 

of dispersants) have impacted sea turtles that have come into contact with oil and remediation efforts. For 

the latest available information on oiled or affected sea turtles documented in the area, refer to NMFS’s 

“Sea Turtles and the Gulf of Mexico Oil Spill” website (USDOC, NMFS, 2011c).

According to this NMFS website, 1,146 sea turtles have been collected (537 alive, 609 deceased) as 

of February 15, 2011). Of these, 201 were greens, 16 Hawksbills, 809 Kemp’s ridleys, 88 loggerheads, 

and the remaining 32 unknown (USDOC, NMFS, 2011c). Individuals were documented either through 

strandings or directed offshore captures. Due to low detection rates of carcasses in prior events, it is 

possible that the number of deaths of sea turtles is underestimated (Epperly et al., 1996). It is also 

important to note that evaluations have not yet confirmed the cause of death, and it is possible that not all 

carcasses were related to the Deepwater Horizon explosion, oil spill, and response. Over the last 2 years, 

NOAA has documented increased numbers of sea turtle strandings in the northern GOM. Many of the 

stranded turtles were reported from Mississippi and Alabama waters, and very few showed signs of 

external oiling (believed to be related to the Deepwater Horizon explosion, oil spill, and response). 

Necropsy results from many of the stranded turtles indicate mortality due to forced submergence, which is 

commonly associated with fishery interactions. In May 2012, NMFS published the Draft EIS to reduce 

incidental bycatch and mortality of sea turtles in the southeastern U.S. shrimp fishery (Federal Register, 

2012). Further detail on this catastrophic OSRA run is contained in Appendix C. 

The Ixtoc I well blowout and spill in the Bay of Campeche, Mexico, on June 3, 1979, resulted in the 

release of 500,000 metric tons (140 million gallons) of oil and the transport of this oil into the Gulf of 

Mexico (ERCO, 1982). Three million gallons of oil impacted Texas beaches (ERCO, 1982). According 

to the ERCO study, “Whether or not hypoxic conditions could, in fact, be responsible for areawide 
Catastrophic Spill Event Analysis B-61

reductions in [invertebrate] faunal abundance is unclear, however.” Of the three sea turtles found dead in 

the U.S., all had petroleum hydrocarbons in the tissues examined, and there was selective elimination of 

portions of this oil, indicating chronic exposure (Hall et al., 1983). Therefore, the effects of the Ixtoc I

well blowout and spill on sea turtles in waters off Texas are still unknown.

Phase 3—Onshore Contact

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response, and on oil initially reaching the shoreline during the spill event or while the oil still persists in 

the offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. The re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 

contacted shore. Potential impacts reflect the spill and response in very shallow coastal waters and once 

along the shoreline. Season and temperature variations can result in different resource impacts due to 

variations in oil persistence and oil and dispersant toxicity and because of differences in potential 

exposure of the resources throughout various life cycle stages.

Out of the five species of sea turtle that occur in the Gulf of Mexico, only four nest in the GOM. The 

largest nesting location for the Kemp’s ridley sea turtle is in Rancho Nuevo, Mexico, but they also nest in 

Texas and Alabama. Loggerhead sea turtles nest in all states around the Gulf of Mexico. Green sea 

turtles have been cited nesting in Texas, Alabama, and Florida. Leatherback sea turtles mostly nest on the 

east coast of Florida but are recorded in Texas. Kemp’s ridley, loggerhead, and green sea turtles are 

therefore most likely to be affected by a catastrophic oil spill when there is onshore and/or offshore 

contact.

Female sea turtles seasonally emerge during the warmer summer months to nest on beaches. 

Thousands of sea turtles nest along the Gulf Coast, and turtles could build nests on oiled beaches. Nests 

could also be disturbed or destroyed by cleanup efforts. Untended booms could wash ashore and become 

a barrier to sea turtle adults and hatchlings (USDOC, NOAA, 2010d). Hatchlings, with a naturally high 

mortality rate, could traverse the beach through oiled sand and swim through oiled water to reach 

preferred habitats of Sargassum floats. Response efforts could include mass movement of eggs from 

hundreds of nests or thousands of hatchlings from Gulf Coast beaches to the east coast of Florida or to the 

open ocean to prevent hatchlings entering oiled waters (Jernelöv and Lindén, 1981; USDOI, FWS, 

2010b). Due to poorly understood mechanisms that guide female sea turtles back to the beaches where 

they hatched, it is uncertain if relocated hatchlings would eventually return to the Gulf Coast to nest 

(Florida Fish and Wildlife Conservation Commission, 2010). Therefore, shoreline oiling and response 

efforts may affect future population levels and reproduction (USDOI, NPS, 2010). Sea turtle hatchling 

exposure to, fouling by, or consumption of tarballs persisting in the sea following the dispersal of an oil 

slick would likely be fatal. 

As a preventative measure during the Deepwater Horizon explosion, oil spill, and response, NMFS 

and FWS translocated a number of sea turtle nests and eggs that were located on beaches affected or 

potentially affected by spilled oil. According to the latest information on the NMFS stranding network 

website (USDOC, NMFS, 2011c), a total of 274 nests were translocated from GOM beaches to the east 

coast of Florida. These nests were mainly for hatchlings that would enter waters off Alabama and 

Florida’s northwest Gulf Coast. Of these, 4 were from green turtles, 5 from Kemp’s ridley, and 265 were 

loggerheads. The translocation effort ended August 19, 2010, at the time when biologists determined that 

risks to hatchlings emerging from beaches and entering waters off Alabama and Florida’s northwest Gulf 

Coast had diminished significantly and that the risks of translocating nests during late incubation to the 

east coast of Florida outweighed the risks of letting hatchlings emerge into the Gulf of Mexico. The 

hatchlings resulting from the translocations were all released as of September 9, 2010.

In addition to the impacts from contact with hydrocarbons, spill-response activities could adversely 

affect sea turtle habitat and cause displacement from suitable habitat to inadequate areas. Impacting 

factors might include artificial lighting from night operations, booms, machine and human activity, 

equipment on beaches and in intertidal areas, sand removal and cleaning, and changed beach landscape 

and composition. Some of the resulting impacts from cleanup could include interrupted or deterred 

nesting behavior, crushed nests, entanglement in booms, and increased mortality of hatchlings because of 
B-62 Central Planning Area Lease Sales 235, 241, and 247 EIS

predation during the increased time required to reach the water (Newell, 1995; Lutcavage et al., 1997). 

The strategy for cleanup operations should vary, depending on the season.

Phase 4—Post-Spill, Long-Term Recovery and Response

Phase 4 focuses on long-term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 

killed and that cleanup activities are concluding. While it is assumed that the majority of spilled oil 

would be dissipated offshore within 1-2 months (depending on season and temperature) of stopping the 

flow, oil has the potential to persist in the environment long after a spill event and has been detected in 

sediment 30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and 

salt marshes, oil may seep into the muddy bottoms. Potential impacts reflect long-term persistence of oil 

in the environment and residual and long-term cleanup efforts.

Sea turtles take many years to reach sexual maturity. Green sea turtles reach maturity between 20 and 

50 years of age; loggerheads may be 35 years old before they are able to reproduce; and hawksbill sea 

turtles typically reach lengths of 27 in (69 cm) for males and 31 in (79 cm) for females before they can 

reproduce (USDOC, NMFS, 2010b). Declines in the food supply for sea turtles, which include 

invertebrates and sponge populations, could also affect sea turtle populations. While all of the pathways 

that an oil spill or the use of dispersants can affect sea turtles is poorly understood, some pathways may 

include the following: (1) oil or dispersants on the sea turtle’s skin and body can cause skin irritation, 

chemical burns, and infections; (2) inhalation of volatile petroleum compounds or dispersants can damage 

the respiratory tract and lead to diseases; (3) ingesting oil or dispersants may cause injury to the 

gastrointestinal tract; and (4) chemicals that are inhaled or ingested may damage internal organs. In most 

foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick 

would result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity and increased 

vulnerability to disease) to sea turtles. Other possible internal impacts might include harm to the liver, 

kidney, and brain function, as well as causing anemia and immune suppression, or they could lead to 

reproductive failure or death. The deaths of subadult and adult sea turtles may also drastically reduce the 

population.

Since January 1, 2011, a notable increase in sea turtle strandings has occurred in the northern GOM, 

primarily in Mississippi. While turtle strandings in this region typically increase in the spring, the recent 

increase is a cause for concern. The Sea Turtle Stranding and Salvage Network is monitoring and 

investigating this increase. The network encompasses the coastal areas of the 18 states from Maine 

through Texas and includes portions of the U.S. Caribbean. There are many possible reasons for the 

increase in strandings in the northern GOM, both natural and human caused (USDOC, NMFS, 2012c). 

One sea turtle had a small amount of tar from the Deepwater Horizon explosion, oil spill, and response on 

its shell. No visible external or internal oil was observed in any other animals. These sea turtle species 

include loggerhead, green, Kemp’s ridley, leatherback, hawksbill, and unidentified. As of July 29, 2012, 

NMFS has identified 81 strandings in Texas (upper Texas coast – Zone 18).

Over the last 2 years, NOAA has documented necropsy results from many of the stranded turtles, 

indicating mortality due to forced submergence, which is commonly associated with fishery interactions, 

and acute toxicosis. On May 10, 2012, NMFS published the Draft EIS to reduce incidental bycatch and 

mortality of sea turtles in the southeastern U.S. shrimp fishery (77 FR 27411) (Federal Register, 2012).

Overall Summary and Conclusion (Phases 1-4)

Accidental blowouts, oil spills, and spill-response activities resulting from a CPA proposed action 

have the potential to impact small to large numbers of sea turtles in the GOM, depending on the 

magnitude and frequency of accidents, the ability to respond to accidents, the location and date of 

accidents, and various meteorological and hydrological factors. Impacts on sea turtles from smaller 

accidental events are likely to affect individual sea turtles in the spill area, but they are unlikely to rise to 

the level of population effects (or significance) given the size and scope of such spills. 

Unavailable information on the effects to sea turtles from the Deepwater Horizon explosion, oil spill, 

and response and increased stranding events (and thus changes to the sea turtle baseline in the affected 

environment) makes an understanding of the effects less clear.
Catastrophic Spill Event Analysis B-63

For low-probability catastrophic spills, this analysis concludes that there is a potential for a lowprobability catastrophic event to result in significant, population-level effects on affected sea turtle 

species.

B.3.1.14. Diamondback Terrapins

Phase1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout event. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1-2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. 

Potential impacts reflect the explosion, subsequent fire for 1-30 days and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well.

The scenarios for each phase, including cleanup methods, can be found in Table B-4. 

There would likely be no adverse impacts to diamondback terrapins as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event 

because these species exclusively inhabit estuarine waters and salt marshes. 

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. Potential 

impacts reflect spill and response in Federal and State offshore waters. Season and temperature variations 

can result in different resource impacts due to variations in oil persistence and oil and dispersant toxicity 

and because of differences in potential exposure of the resources throughout various life cycle stages.

There would likely be no adverse impacts to diamondback terrapins as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 2 of a catastrophic spill event 

because these species exclusively inhabit estuarine waters and salt marshes. 

Phase 3—Onshore Contact 

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response and on oil initially reaching the shoreline during the spill event or while the oil still persists in 

the offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. The re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 

contacted shore. Potential impacts reflect the spill and response in very shallow coastal waters and once 

along the shoreline. Season and temperature variations can result in different resource impacts due to 

variations in oil persistence and oil and dispersant toxicity and because of differences in the potential 

exposure of the resources throughout various life cycle stages.

The major impact-producing factors resulting from the low-probability catastrophic event at may 

affect the five terrapin subspecies that occur in the WPA and CPA include offshore and coastal oil spills

and spill-response activities.

Terrapins inhabit brackish waters including coastal marshes, tidal flats, creeks, and lagoons behind 

barrier beaches (Hogan, 2003). Their diet consists of fish, snails, worms, clams, crabs, and marsh plants 

(Cagle, 1952). Courtship and mating occur in March and April, and the nesting season extends through 

July, with possibly multiple clutches (U.S. Dept. of the Army, COE, 2002; Butler et al., 2006). Terrapins 

nest on dunes, beaches, sandy edges of marshes, islands, and dike roads (Roosenburg, 1994). The 
B-64 Central Planning Area Lease Sales 235, 241, and 247 EIS

common factor for proper egg development is sandy soil, which does not clog eggshell pores, thus 

allowing sufficient gas exchange between the developing embryo and the environment (Roosenburg, 

1994). Nesting occurs primarily in the daytime during high tide on high sand dunes with gentle slopes 

and minimal vegetation (Burger, 1977). Clutch size ranges from 4 to 22 eggs, and incubation time ranges 

from 61 to 104 days (Butler et al., 2006; Burger, 1977). Female terrapins may nest 2-3 times in the same 

nesting season. Gender determination is temperature dependent. Hatching occurs from July through 

October in northeastern Florida (Butler et al., 2004).

Spending most of their lives at the aquatic-terrestrial boundary in estuaries, terrapins are susceptible 

to habitat destruction from oil-spill cleanup efforts as well as direct contact with oil. However, most 

impacts cannot be quantified at this time. Even after oil is no longer visible, terrapins may still be 

exposed while they forage in the salt marshes lining the edges of estuaries, where oil may have 

accumulated under the sediments and within the food chain. Terrapin nests can also be disturbed or 

destroyed by cleanup efforts. The range of the possible chronic effects from contact with oil and 

dispersants include lethal or sublethal oil-related injuries that may include skin irritation from the oil or 

dispersants, respiratory problems from the inhalation of volatile petroleum compounds or dispersants, 

gastrointestinal problems caused by the ingestion of oil or dispersants, and damage to other organs 

because of the ingestion or inhalation of these chemicals.

Accidental blowouts, oil spills, and spill-response activities resulting from a CPA proposed action 

have the potential to impact small to large numbers of terrapins within their habitat, depending on the 

magnitude and frequency of accidents, the ability to respond to accidents, the location and date of 

accidents, and various meteorological and hydrological factors. Populations of terrapins in the Gulf may 

be exposed to residuals of oils spilled as a result of a CPA proposed action during their lifetimes. Chronic 

or acute exposure may result in the harassment, harm, or mortality to terrapins occurring in the GOM. In 

the most likely scenarios, exposure to hydrocarbons persisting within the wetlands following the dispersal 

of an oil slick could result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; 

and increased vulnerability to disease). Terrapin hatchling exposure to, fouling by, or consumption of 

tarballs persisting inland following the dispersal of an oil slick could likely be fatal but unlikely. Impacts 

from the dispersants are unknown, but they may have similar irritants to tissues and sensitive membranes 

as are known to occur in seabirds and sea turtles (NRC, 2005). The impacts to diamondback terrapins

from chemical dispersants could include nonlethal injury (e.g., tissue irritation and inhalation), long-term 

exposure through bioaccumulation, and potential shifts in distribution from some habitats.

Burger (1994) described the behavior of 11 female diamondback terrapins that were oiled during the 

January 1990 spill of No. 2 fuel oil in Arthur Kill, New York. The terrapins were hibernating at the time 

of the spill, and when they emerged from hibernation, they were found to be oiled. The terrapins voided 

oil from their digestive tracks for 2 weeks in rehabilitation. At 3 weeks, the terrapins scored low on 

strength tests and were slow to right themselves when placed on their backs. At 4 weeks, they developed 

edema and appetite suppression. Eight of the 11 died; these animals had traces of oil in their tissues and 

exhibited lesions in their digestive tract consistent with oil exposure (Burger, 1994). Further detail on this 

catastrophic OSRA run is contained in Appendix C. 

The Deepwater Horizon explosion, oil spill, and response may have potentially impacted the terrapin 

community. Impacts from a catastrophic spill may impact terrapin communities. Impacts can be either 

direct (mortality or injury) or indirect (e.g., reduced prey availability); however, most impacts cannot be 

quantified at this time. The best available information does not provide a complete understanding of the 

effects of the spilled oil and active response/cleanup activities on the potentially affected terrapin 

environment. Current available information includes photographic evidence of one terrapin found oiled 

on Grand Terre Island, Louisiana, on June 8, 2010 (State of Louisiana, Coastal Protection and 

Restoration, 2012).

Phase 4—Post-Spill, Long-Term Recovery and Response

Phase 4 focuses on long term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 

killed and cleanup activities are concluding. While it is assumed that the majority of spilled oil would be 

dissipated offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil 

has the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt 
Catastrophic Spill Event Analysis B-65

marshes, oil may seep into the muddy bottoms. Potential impacts reflect long term persistence of oil in 

the environment and residual and long-term cleanup efforts.

The Deepwater Horizon explosion, oil spill, and response and associated oil spill may have impacted 

the terrapin community and associated brackish habitats. According to OSAT-2 (2011), possible 

environmental effects from the Deepwater Horizon explosion, oil spill, and response could occur within 

terrapin marsh habitat via food or to nesting habitat since no active intervention (natural remediation) is 

the preferred protocol.

Habitat destruction, road construction, drowning in crab traps, and nest predation are the most recent 

threats to diamondback terrapins. Tropical storms, hurricanes, and beach erosion threaten their preferred 

nesting habitats. Destruction of the remaining habitat because of a catastrophic spill and response efforts 

could drastically affect future population levels and reproduction.

Overall Summary and Conclusion (Phases 1-4)

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

diamondback terrapins in the spill area, as described above, but are unlikely to rise to the level of 

population effects (or significance) given the probable size and scope of such spills. Possible catastrophic 

environmental effects from an oil spill and cleanup could occur within terrapin marsh habitat via food or 

to the nesting habitat. Since terrapins do not move far from where they are hatched, it is possible that 

entire subpopulations could incur high mortality rates and community disruptions, though this would be 

highly localized depending on the time, place, and size of the spill.

The OSRA analyses in this Supplemental EIS conclude that there is a low probability for catastrophic 

spills and that there is a potential for a low-probability catastrophic event to result in significant, 

population-level effects on affected diamondback terrapin species.

For those terrapin populations that may not have been impacted by the Deepwater Horizon explosion, 

oil spill, and response, it is unlikely that a future accidental event related to a CPA proposed action would 

result in significant impacts due to the distance of most terrapin habitat from offshore OCS energy-related 

activities.

B.3.1.15. Beach Mice

Phase 1—Initial Event

There would likely be no adverse impacts to beach mice as a result of the events and the potential 

impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event because 

Phase 1 is the initiation of a catastrophic blowout incident, and initiation would occur well offshore from 

beach mouse habitat.

Phase 2—Offshore Spill

There would likely be no adverse impacts to beach mice as a result of the events and the potential 

impact-producing factors that could occur throughout Phase 2 of a catastrophic spill event because 

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters away from 

beach mouse habitat.

Phase 3—Onshore Contact

Five subspecies of the field mouse, collectively known as beach mice, live along the Gulf Coast, and 

two beach mouse subspecies live on the Atlantic Coast of Florida. Five subspecies of beach mice 

(Alabama, Perdido Key, Choctawhatchee, St. Andrew, and Anastasia Island) are listed as State and 

federally endangered; also, the southeastern beach mouse is listed as federally threatened. Beach mice are 

restricted to the coastal barrier sand dunes along the Gulf Coasts of Alabama and Florida. Erosion caused 

by the loss of vegetation because of oiling would likely cause more damage than the direct oiling of beach 

mice because of the degradation or loss of habitat. In addition, vehicular traffic and activity associated 

with cleanup can trample or bury beach mice nests and burrows or cause displacement from preferred 

habitat. Improperly trained personnel and vehicle and foot traffic during shoreline cleanup of a 

catastrophic spill would disturb beach mouse populations and would degrade or destroy habitat.
B-66 Central Planning Area Lease Sales 235, 241, and 247 EIS

The Alabama, Choctawhatchee, St. Andrew, Perdido Key, Anastasia Island, and southeastern beach 

mice are designated as protected species under the Endangered Species Act, mostly because of the loss 

and fragmentation of coastal habitat (Federal Register, 1989; USDOI, MMS, 2007). Some of the 

subspecies have coastal habitat that is designated as their critical habitat. For example, the endangered 

Alabama beach mouse’s (Peromyscus polionotus ammobates) designated critical habitat is 1,211 acres 

(450 hectares) of frontal dunes covering just 10 mi (16 km) of shoreline (USDOI, FWS, 2007). Critical 

habitat is the specific geographic areas that are essential for the conservation of a threatened or 

endangered species.

All designated critical habitat for beach mice officially extends landward from the mean high water 

line (Federal Register, 2006; USDOI, FWS, 2007). Therefore, spilled oil could contact critical habitat 

even without a concurrent storm surge; contact would require only that the water level would be at mean 

high tide. However, a concurrent storm surge of considerable height would be required to oil the portion 

of the critical habitat substantially landward of the mean high water line (over the tops of the primary, 

secondary, and tertial dunes). With the potential oiling of over 1,000 mi (1,609 km) of shoreline that 

could result from a catastrophic spill event and a concurrent storm surge of considerable height that 

occurs within a close proximity to the critical habitat, there is the potential for the entire critical habitat 

for a subspecies of beach mice to be completely oiled. Thus, destruction of critical habitat because of a 

catastrophic spill, a concurrent storm surge of considerable height and over a considerable length of 

shoreline, and cleanup activities would increase the threat of extinction of several subspecies of beach 

mice. Further detail on this catastrophic OSRA run is contained in Appendix C. 

Phase 4—Post-Spill, Long-Term Recovery and Response

Within the last 20-30 years, the combination of habitat loss because of beachfront development, the 

isolation of the remaining beach mouse habitat areas and populations, and the destruction of the 

remaining habitat by tropical storms and hurricanes has increased the threat of extinction of several 

subspecies of beach mice. On sandy beaches, oil can sink deep into the sediments and become exposed 

again after erosion of sand by wave action. Oil may therefore persist near beach mouse habitat for the 

long term. The destruction of the remaining habitat because of a catastrophic spill and cleanup activities 

would increase the threat of extinction.

Overall Summary and Conclusion (Phases 1-4)

Impacts to beach mice would vary according to the severity of the oiling. Further detail on this 

catastrophic OSRA run is contained in Appendix C. 

B.3.1.16. Coastal, Marine, and Migratory Birds

Phase 1—Initial Event

Some migratory birds use offshore platforms or rigs as potential stopover sites during their longdistance migrations across the GOM during the spring and fall (Russell, 2005). In addition, it has been 

well documented that seabirds are attracted to offshore platforms and rigs for a myriad of reasons; i.e., 

concentrations of baitfish, roost sites, etc. (Tasker et al., 1986; Wiese et al., 2001; Burke et al., 2012). 

The numbers of birds present at a platform or rig tend to be greater on platforms or rigs closer to shore, 

particularly during drilling operations (Baird, 1990). Birds resting on the drilling rig or platform during a 

catastrophic blowout at the surface (similar to the Deepwater Horizon explosion, oil spill, and response) 

are more likely to be killed by the explosion. While it is assumed that most birds in trans-Gulf migration 

would likely avoid the fire and smoke plume during the day, it is possible that the light from the fire could 

interfere with nocturnal migration, especially during poor visibility conditions, i.e., fog or low clouds. It 

has been documented that seabirds are attracted to natural gas flares at rigs and platforms (Russell, 2005; 

Wiese et al., 2001); therefore, additional bird fatalities could result from the fire following the blowout. 

Though different species migrate differentially throughout the year, the largest number of species 

migrates through the proposed area from mid-April through mid-May (spring migration back north) and 

from mid-August through early November (fall migration south) (Russell, 2005, Table 6.12; Farnsworth 

and Russell, 2007). A blowout during this time would potentially result in a greater number of bird 

fatalities (see below).
Catastrophic Spill Event Analysis B-67

Of the four phases considered herein, avian mortality associated with this Phase is certainly expected 

to be much lower than avian mortality associated with either Phase 2 or Phase 3. However, this 

anticipated result is highly dependent on the location of the platform and the timing of the event. The 

only scenario considered is the case where a blowout and explosion occurred at the surface (Table B-4). 

If the catastrophic event, in this case a blowout and explosion at the surface (refer to Table B-4), occurs 

more proximal to the coast during the breeding season or during a peak migration period (late March to 

late May and mid-August to early November), then the level of avian mortality is expected to be higher. 

In comparison, a blowout and explosion at the surface on a platform more distant from the coast (greater 

than or equal to the distance of the Macondo well from the coast) would result in much lower avian 

mortality, particularly if the event did not overlap temporally with either the breeding season or either of 

the trans-Gulf migrations.

While the species composition and species-specific mortality estimates are unknown and would be 

dependent on the blowout location and time of year, the initial mortalities would almost certainly not 

result in population-level impacts for species present at the time of the blowout and resulting fire (Arnold 

and Zink, 2011; also refer to Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS). If the event occurred 

during the breeding season or wintering period, species of seabirds or diving birds would have the 

greatest potential to be affected, whereas if the event occurred during either the spring or fall migration, 

species of passerines would most likely have the greatest potential to be affected due to the diversity and 

sheer numbers of individuals in this avian species group (Rappole and Ramos, 1994; Lincoln et al., 1998; 

Russell, 2005; also refer to Chapter 4.1.1.16 of this Supplemental EIS, Chapter 4.2.1.16.1 of the 2012-

2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS). 

Phase 2—Offshore Spill

During Phase 2 of a catastrophic spill, the primary concern for marine and migratory birds would be 

their vulnerability to oiling or ingesting oil, which is primarily a function of their behavior and diets. 

Wading birds (e.g., herons, egrets, etc.) and species that feed by plunge-diving into the water to catch 

small fish (e.g., pelicans, gannets, terns, gulls, and pelagic birds) and those that use water as a primary 

means of locomotion, foraging (e.g., black skimmers), or resting and preening (e.g., diving ducks, 

cormorants, pelicans, etc.) are highly vulnerable to becoming oiled and also to ingesting oil (Table B-5 of 

this Supplemental EIS; also refer to Table 4-13 and Figure 4-13 of the 2012-2017 WPA/CPA Multisale 

EIS). Seabirds, in particular, tend to feed and concentrate in convergence zones, eddies, upwellings, and 

near Sargassum mats (Haney, 1986a-c; Moser and Lee, 2012). In addition to concentrating prey, these 

areas are also known to aggregate oil (Unified Incident Command, 2010d). Oiling interferes with the 

birds’ ability to fly (thus to obtain food) and compromises the insulative characteristics of down and 

contour feathers, making it difficult to regulate body temperature. Attempts by oiled birds to remove the 

oil via preening can cause them to ingest oil and may result in mortality. In addition, the ingestion of 

contaminated prey can result in physiological impairment and even death. Refer to Chapter 4.2.1.16.3 of 

the 2012-2017 WPA/CPA Multisale EIS for additional detailed information on oiling effects to birds.

Though several species or species groups are mentioned above, the most vulnerable species to spilled 

oil in the offshore environment in the GOM during Phase 2 would be representatives of the diving bird 

(≤10 species) and seabird (≥20 species) groups (King and Sanger, 1979; Ribic et al., 1997; Davis et al., 

2000). Unlike Phase 1, where passerines may be affected depending on the timing of the catastrophic 

event, timing or seasonal effects would be less important under the Phase 2 scenario (Table B-4) due to 

the spilled oil being restricted to the offshore environment, thereby limiting the potential impacts to the 

several avian species groups relegated to the coastal and nearshore environment (Table B-5 of this 

Supplemental EIS; also refer to Chapter 4.1.1.16 of this Supplemental EIS, Chapter 4.2.1.16.1 of the 

2012-2017 WPA/CPA Multisale EIS, and Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS). 

However, it is highly probable that representative species of diving birds and seabirds would differentially 

be impacted (Table B-5 of this Supplemental EIS; also refer to Table 4-12 of the 2012-2017 WPA/CPA 

Multisale EIS). Table 4-12 of the 2012-2017 WPA/CPA Multisale EIS shows the actual number of birds 

identified to the species level for each of the species groups. This number is fairly representative of the 

suite of species available to be oiled. However, this number is dependent on efforts to correctly assign 

species to unidentified birds or unknowns, which is also a function of search effort. Search effort likely 

declined dramatically once the Macondo well was plugged/capped. The species composition and speciesspecific mortality estimates associated with a Phase 2 catastrophic event are unknown and would be 
B-68 Central Planning Area Lease Sales 235, 241, and 247 EIS

dependent primarily on the blowout location, as well as the distribution, coverage, and proximity to the 

shoreline of spilled oil. Overall, avian mortalities for this Phase would probably not result in populationlevel impacts for species present at the time of the blowout (refer to Table B-5 of this Supplemental EIS 

and to Figure 4-13 of the 2012-2017 WPA/CPA Multisale EIS). However, it should be clear that many 

species of seabirds and diving birds have life-history strategies that do not allow subpopulations to 

recover quickly from major mortality events or perturbations (Ricklefs, 1983 and 1990; Russell, 1999; 

Saether et al., 2004; also refer to Table 4-13 and Figure 4-18 of the 2012-2017 WPA/CPA Multisale EIS).

Some discussion of available information provided from the Deepwater Horizon explosion, oil spill, 

and response is relevant here with respect to temporal aspects of oiled birds (Figure B-3). The first oiled 

bird (northern gannet, a seabird) recovered after the Macondo well event was collected just 10 days postblowout. While gannets breed in coastal colonies in the Canadian North Atlantic, the population, 

including a major concentration in the northern GOM, over-winters in the deeper waters of the offshore 

environment. Belanger et al. (2010) provided some interesting results relative to live versus dead birds 

collected based on the actual date each bird was collected. Interestingly, they documented a dramatic and 

statistically significant decline in the number of live birds collected after 110 days compared with live 

birds collected during the first 72 days. These authors also documented a dramatic and statistically 

significant increase in the number of dead birds collected after 110 days (Belanger et al., 2010, Figures 2 

and 3). As a temporal reference, oil reached the shoreline near Venice, Louisiana, ≥10 days postblowout, covering a distance of approximately 90 mi (145 km) (Oil Spill Commission, 2011; also refer to

Chapter 4.2.1.3.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.3 of the WPA 233/CPA 

231 Supplemental EIS) (Figure B-3). It should be understood that, for the Phase 2 scenario considered 

here, it is assumed that spilled oil will not contact the shoreline.

Overall, avian mortality estimates are unknown and are difficult to predict given the uncertainty 

(Conroy et al., 2011, pages 1209-1210; Williams, 2011, page 1348) associated with the scenario and 

specific characteristics associated with the spill (refer to Appendix C), as well as environmental 

conditions that are probably a function of spill location and timing. Even recognizing the uncertainty 

associated with the scenario, spill characteristics, and the environmental conditions at the time of the spill, 

Phase 2 would likely be second only to Phase 3 in total avian mortality. Phase 3 would include much 

greater avian species diversity and abundance due to the oil reaching nearshore, coastal beach/dune, saltand brackish marsh habitats (Table B-5 of this Supplemental EIS; also refer to Table 4-12 of the 2012-

2017 WPA/CPA Multisale EIS).

Phase 3—Onshore Contact

Gulf coastal habitats are essential to the annual cycles of many species of breeding, wintering, and 

migrating diving birds, seabirds, shorebirds, passerines, marsh- and wading birds, and waterfowl (refer to

Chapter 4.1.1.16 of this Supplemental EIS, Chapter 4.2.1.16.1 of the 2012-2017 WPA/CPA Multisale 

EIS, and Chapter 4.2.1.16 of the WPA 233/CPA 231 Supplemental EIS). For example, the northern Gulf 

Coast supports a large proportion of populations of several beach-nesting bird species (USDOI, FWS, 

2011b). During Phase 3, oil is expected to contact not only the beach but also other important habitats 

used by a diverse and abundant assemblage of avian species. Habitats potentially impacted by a 

catastrophic spill would also likely include the nearshore environment, as well as the salt- and brackish 

marsh habitats. Potential impacts and total avian mortality from Phase 3 would be greater than any of the 

other phases considered herein due to (1) avian diversity and abundance in the nearshore environment 

(Table B-5 of this Supplemental EIS; also refer to Tables 4-9 through 4-11 of the 2012-2017 WPA/CPA 

Multisale EIS) and (2) the dispersion of oil from a catastrophic spill, which would reach the shoreline and 

enter the salt- and brackish marsh environments. Similar to Phases 1 and 2, the timing and location of the 

spill are important factors in determining the severity of impacts to the avian community. In addition, the 

duration of potential oil exposure to various species of birds would also be important.

As the Macondo well blowout and spill is the only historic catastrophic oil spill to occur in U.S. 

waters in the GOM, the information obtained from the Deepwater Horizon explosion, oil spill, and 

response relative to avian mortality may be reasonably relevant for any future catastrophic spills, 

recognizing of course the variation and uncertainty associated with individual oil spills. At present, the 

estimates of avian mortality associated with the Exxon Valdez oil spill far exceed current estimates of 

avian mortality associated with the Deepwater Horizon explosion, oil spill, and response even though the 

Deepwater Horizon spill volume/size far exceed that of the Exxon Valdez (refer to Table 4-15 of the 
Catastrophic Spill Event Analysis B-69

2012-2017 WPA/CPA Multisale EIS). Based on data from the Deepwater Horizon explosion, oil spill, 

and response, a similar catastrophic spill would probably result in >10,000 carcasses collected 

(Deepwater Horizon explosion, oil spill, and response = 7,258 collected) representing >100 potentially 

impacted species (Deepwater Horizon explosion, oil spill, and response = 104 species identified) (refer to 

Table B-5, superscript 1 and also superscript b). It should be recognized that the number of avian 

carcasses collected post-spill represents some unknown fraction or proportion of the total modeled 

estimate of realized mortality (Flint et al., 1999; Byrd et al., 2009; Ford and Zafonte, 2009); the number 

of avian carcasses collected is biased low (Piatt et al., 1990a-b; Piatt and Ford, 1996; Castege et al., 

2007). Figure 4-13 of the 2012-2017 WPA/CPA Multisale EIS should provide reasonable estimates of 

oiling rates for the seven avian species groups in the northern Gulf of Mexico if another catastrophic spill 

were to occur and the timing, oil spill characteristics, and spill behavior were similar to the Deepwater 

Horizon explosion, oil spill, and response. It should be noted that the top five most impacted (based on 

number collected) avian species from the Deepwater Horizon explosion, oil spill, and response were all 

representatives of the seabird group: laughing gull (n = 2,981, 40% oiling rate); brown pelican (n = 826, 

41% oiling rate); northern gannet (n = 475, 63% oiling rate); royal tern (n = 289, 52% oiling rate); and 

black skimmer (n = 253, 22% oiling rate) (Table B-5 of this Supplemental EIS and Figure 4-13 of the 

2012-2017 WPA/CPA Multisale EIS).

Additional information is provided herein from an OSRA catastrophic oil-spill analysis (refer to 

Appendix C, Tables C-4 and C-5). 

It should be noted that oil from the Deepwater Horizon explosion and oil spill reached the shoreline 

less than 14 days after the blowout occurred (Oil Spill Commission, 2011). The OSRA does not take into 

account or consider the following with respect to avian resources and their habitats: (1) species-specific 

densities; (2) species-specific habitat preferences, food habits, or behavior; (3) relative vulnerabilities to 

oiling among the avian species groups or among species within each of the groups (Table B-5 of this 

Supplemental EIS and Figure 4-13 of the 2012-2017 WPA/CPA Multisale EIS; also refer to Williams 

et al., 1995; Camphuysen, 2006); and (4) it does not take into account or consider species-specific lifehistory strategies, their demography, or a species’ recovery potential (refer to Table 4-13 and Figures 4-18 

and 4-19 of the 2012-2017 WPA/CPA Multisale EIS). 

In summary, Phase 3 of a catastrophic oil spill has the greatest potential for negative impacts (i.e., 

direct mortality) to avian resources due to its contact with the shoreline and inundation of other habitats 

occupied by a much greater diversity and abundance of birds, particularly during the breeding season. 

Avian mortality estimates are presently unknown and are difficult to predict with any level of precision 

given the uncertainty associated with the scenario, specific characteristics associated with the spill, spatial 

and temporal variation in environmental conditions, and recognition that the avian resources (both species 

diversity and abundance) available to be oiled will also vary temporally and spatially. A worst-case 

scenario in the event of a catastrophic oil spill that reached the nearshore environment would occur in the 

presence of a hurricane with strength or magnitude similar to Hurricanes Katrina, Rita, or Ike during the 

breeding season. Such an overlap of two low-probability events during the breeding season could 

potentially push spilled oil even farther inland and also distribute oil vertically into the vegetation. Such 

an event would not only negatively impact diving birds, seabirds, shorebirds, marsh- and wading birds, 

and waterfowl but also the more terrestrial avian species groups including passerines and raptors. Such 

effects would most likely be long-term (due to direct mortality of individuals, but also due to major 

habitat loss) and could potentially result in population-level impacts to a number of avian species. 

Threatened and endangered avian species would likely be the most severely impacted by such an event 

depending on the spatial and temporal aspects of both the spill and the hurricane.

Endangered and Threatened Birds 

A detailed discussion of threatened and endangered species is provided in Chapter 4.2.1.16.1 of the 

2012-2017 WPA/CPA Multisale EIS. Of the 17 species considered, 11 species are known to occur in the 

CPA (Table B-6). However, only the piping plover (Charadrius melodus), roseate tern (Sterna dougallii 

dougallii), wood stork (Mycteria americana), whooping crane (Grus americana), Mississippi sandhill 

crane (Grus canadensis pulla), bald eagle (Haliaeetus leucocephalus), eastern brown pelican (Pelecanus 

occidentalis), and red knot (Calidris canutus rufa) were analyzed and are considered further here. 

Phase 3 would likely result in the greatest net negative impacts (primarily direct mortality) to threatened 

and endangered avian species due to contact with the shoreline and potential movement of spilled oil 
B-70 Central Planning Area Lease Sales 235, 241, and 247 EIS

inland to other habitats during this phase (Table B-4). In addition, the presence of spilled oil would result 

in indirect and potentially long-term effects to threatened and endangered avian species’ habitats and their 

preferred foods. Phases 1 and 2 would likely result in very limited impacts, if any, due to the scenarios as 

defined with oil restricted to the offshore environment.

In general, the potential direct impact (i.e., mortality) to any or all of these threatened or endangered 

(including recently delisted and candidate) species is directly a function of their presence at the time of a 

catastrophic oil spill. Indirect effects from a catastrophic oil spill could negatively affect the quality and 

functional availability of their habitats and the availability, distribution, and energetic benefits of their 

preferred foods in the absence of a given species. Of the species listed, the wood stork, Mississippi 

sandhill crane, bald eagle, eastern brown pelican, and Cape Sable seaside sparrows are year-round 

residents, whereas the piping plover, roseate tern, whooping crane, and red knot represent either wintering 

species or transients that utilize coastal habitats in the GOM as staging areas during migration. There are 

“resident” whooping cranes considered as “nonessential, experimental flocks” within the Gulf Coast 

States of Alabama, Louisiana, Mississippi, and Florida. These birds would be considered as “resident,” 

whereas the component of the ESA-listed species occurring primarily as a wintering flock in Texas (i.e., 

the Aransas National Wildlife Refuge) is considered a migratory flock. It is important to recognize these 

differences relative to whether or not individuals of a given species would be present and available to be 

oiled should a catastrophic oil spill event occur. Similarly, species-specific differences in habitat use and 

behavior would further separate which species would be most vulnerable to a spill given the timing of the 

spill, spill distribution, and other spill-related characteristics.

Of the species considered, probably only the eastern brown pelican and possibly the bald eagle 

(ingestion of contaminated fish and birds) would potentially be impacted during Phases 1 and 2. The 

other species are restricted to the nearshore, coastal, salt- and brackish, and upland habitats, which would 

not be impacted during these phases given the scenario (Table B-4). Phase 4 impacts to threatened and 

endangered avian species would probably be limited to short-term disturbance-related effects and 

potential impacts to habitats including destruction, alteration, or fragmentation from associated recovery 

activities (ABC, 2010; NASI, 2010).

As the Macondo well blowout and spill is the only historic catastrophic oil spill to occur in U.S. 

waters in the GOM, the information obtained from the Deepwater Horizon explosion, oil spill, and 

response relative to avian mortality may be reasonably relevant for any future catastrophic spills, 

recognizing of course the variation and uncertainty associated with individual oil spills. Of the threatened 

and endangered avian species considered, only a single, unoiled piping plover was collected as part of the 

post-Deepwater Horizon explosion, oil spill, and response monitoring program (Table B-5). There were 

106 least terns (Sterna antillarum) collected (n = 106, 46% oiling rate), but these individuals were 

considered as members of the coastal breeding population and not the ESA-listed population (Interior or 

noncoastal population). Of the species considered, only the eastern brown pelican was impacted by the 

Deepwater Horizon explosion, oil spill, and response (n = 826, 41% oiling rate); this species was delisted 

on November 17, 2009 (Federal Register, 2009). No other carcasses of threatened and endangered 

species were collected as part of the post-Deepwater Horizon explosion, oil spill, and response

monitoring efforts (Table B-5; USDOI, FWS, 2011b).

Additional information is provided herein from an OSRA catastrophic oil-spill analysis (refer to 

Appendix C, Tables C-4 and C-5). 

Caveats regarding the OSRA catastrophic run with respect to avian resources were addressed above 

and would also apply to threatened and endangered avian resources considered here.

Phase 4—Post-Spill, Long-Term Recovery and Response

There is a high probability of underestimating the impacts of oil spills on avian species potentially 

encountering oil. Despite being oiled, some birds are capable of flight and may later succumb to the 

oiling for a myriad of reasons (refer to Chapter 4.2.1.16 of the 2012-2017 WPA/CPA Multisale EIS for 

additional detailed information). Often overlooked and understudied are the long-term, sublethal, chronic 

effects due to sublethal exposure to oil (Butler et al., 1988; Alonso-Alvarez et al., 2007; Pérez et al., 

2010). Also, individuals having been oiled in the Gulf of Mexico as the result of a catastrophic oil spill 

during the overwinter period or while staging in the GOM could exhibit carry-over effects to the northern 

breeding grounds. Affected individuals in poor body condition may arrive at their breeding grounds later 

than nonaffected individuals, which could, in turn, negatively affect habitat-use decisions, territory 
Catastrophic Spill Event Analysis B-71

establishment, pairing success, and ultimately lead to reduced reproductive success (Norris, 2005 and 

2006; Harrison et al., 2011; Mitchell et al., 2011). Some oiled individuals may forego breeding altogether 

(Zabala et al., 2010). If oil-affected, long-distance migrants represent important prey items for various 

species of raptors, then the ingestion of affected individuals could also negatively affect individual birds 

of prey (Zuberogoitia et al., 2006). Refer to Henkel et al. (2012) for a review of potential carry-over 

effects to shorebirds potentially impacted by the Deepwater Horizon explosion, oil spill, and response. 

The long-term impacts of potential food-induced stress for bird species from an altered ecosystem due 

to a catastrophic spill are unknown, but disturbances to the ecosystem can cause long-term sublethal 

impacts, including reduced food intake, prey switching, increased energy expenditures, decreased 

reproductive success, and decreased survival. Decreases in either reproductive success or survival (or 

both) could result in population-level effects as was observed for certain avian species more than 10 years 

after the Exxon Valdez catastrophic spill (Esler et al., 2002, 2010; Golet et al., 2002). Long-term, 

sublethal, chronic effects may exceed immediate losses (i.e., direct mortality of oiled birds) if residual 

effects influence a significant proportion of the population or disproportionately impact an important 

aspect of the population demographic, i.e., breeding-age females (Croxall and Rothery, 1991; Oro et al., 

2004; Aubry et al., 2011). Depending on the effects and the life-history strategy of impacted species, 

some populations could take years or decades before reaching pre-spill population numbers and age-sex 

structure; some populations for some species may never recover (refer to Figure 4-13 of the 2012-2017 

WPA/CPA Multisale EIS; refer to Peterson et al., 2003, but also to Wiens et al., 2010).

In general, potential effects associated with Phase 4 should be limited to short-term disturbance 

effects (personnel and equipment) and potential indirect effects to various avian species groups due to 

habitat loss, alteration, or fragmentation from restoration efforts. There may be cases whereby incubating 

individuals are flushed from nests exposing their eggs or young to either weather-related mortality or 

depredation by avian or mammalian predators (American Bird Conservancy, 2010; National Audubon 

Society, Inc., 2010). However, efforts to minimize potential effects of post-oil spill monitoring and 

restoration efforts, particularly during the breeding season, should be sufficient to protect nesting birds as 

a function of oversight by Federal and State agencies charged with the conservation of migratory bird 

resources.

Limited information available to date with respect to avian impacts from the Deepwater Horizon

explosion, oil spill, and response suggests much lower mortality than would have been predicted by the 

spill size or volume alone (Belanger et al., 2010), though spill volume or size tends to be a poor predictor 

of avian mortality (Burger, 1993; Tan et al., 2010). The final modeled estimates of avian mortality will 

greatly exceed the number of avian carcasses collected (n = 7,258; Table B-5), but overall, the Deepwater 

Horizon explosion, oil spill, and response appears to have directly resulted in far fewer dead, oiled birds 

than the Exxon Valdez catastrophic spill (refer to Table 4-15 of the 2012-2017 WPA/CPA Multisale EIS). 

It should be recognized that the avian-related mortality associated with the Deepwater Horizon explosion, 

oil spill, and response (considered a catastrophic event) represents a small fraction of birds killed when 

compared with collisions with offshore oil and gas platforms. Russell (2005, page 304) states, “an 

average Gulf platform may cause 50 deaths by collision [only] per year,” so using this number, the 

number of deaths the Deepwater Horizon rig would have caused through collisions had it remained intact 

for its 40-year term would be about 2,000. That is about 5,258 less than the number of avian carcasses 

collected due to the Deepwater Horizon explosion, oil spill, and response just given above. In the GOM, 

an estimated 200,000-321,000 avian deaths occur annually; primarily due to collisions with platforms 

(Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS; also refer to Russell, 2005). Over the life of the 

GOM platform archipelago, the estimated total avian mortality is on the order of 7-12 million birds (refer 

to Figure 4-15 of the 2012-2017 WPA/CPA Multisale EIS). Oil spills, regardless of size, are but one of a 

myriad of anthropogenic avian mortality sources. Even the cumulative total avian mortality associated 

with all the North American oil spills to date is only a small fraction when compared with estimates of 

annual avian mortality attributed to collisions with buildings and windows, predation by housecats, and 

collisions with powerlines and communication towers (Klem, 2009; Manville, 2009; Table 4-7 of the 

2012-2017 WPA/CPA Multisale EIS).

Overall Summary and Conclusion (Phases 1-4)

While the species composition and species-specific mortality estimates are unknown and would be 

dependent on the blowout location and time of year, the mortalities for the initial event (Phase 1) would 
B-72 Central Planning Area Lease Sales 235, 241, and 247 EIS

almost certainly not result in population-level impacts for species present at the time of the blowout and 

resulting fire. Seabirds are highly vulnerable to becoming oiled and also to ingesting oil during Phase 2 

(the offshore spill). Even recognizing the uncertainty associated with the scenario, spill characteristics, 

and the environmental conditions at the time of the spill, Phase 2 would likely be second only to Phase 3 

(onshore contact) in total avian mortality. Phase 3 would include impacts to much greater avian species’ 

richness and abundance (particularly during the breeding season) due to oil reaching habitats, including 

the nearshore, coastal beaches and dunes, and salt and brackish marshes. In general, the potential effects 

associated with Phase 4 (long-term recovery and response) should be limited to short-term disturbance 

effects (by cleanup personnel and equipment) and potential indirect effects to various bird species groups 

from habitat loss, alteration, or fragmentation from restoration efforts.

Phases 1 (initial event) and 2 (offshore spill) would likely result in very limited impacts to threatened 

and endangered bird species because the two scenarios have oil restricted to the offshore environment. 

Phase 3 (onshore contact) would likely result in the greatest net negative impacts to threatened and 

endangered bird species due to contact with the shoreline and potential movement of spilled oil inland to 

other habitats during this phase.

B.3.1.17. Fish Resources and Essential Fish Habitat

Phase 1—Initial Event

Depending on the type of blowout and the proximity of marine life to it (Table B-1), an eruption of 

gases and fluids may generate not only a toxic effect but also pressure waves and noise significant enough 

to injure or kill local biota. Within a few thousand meters of the blowout, resuspended sediments may 

clog fish gills and interfere with respiration. Settlement of resuspended sediments may, in turn, smother 

invertebrates or interfere with their respiration. Essential fish habitat (EFH) in the vicinity of the blowout 

could have adverse effects from the event. These EFH resources are discussed in the water quality

(Chapter B.3.1.1.2), live bottoms (Chapter B.3.1.1.6), topographic features (Chapter B.3.1.1.7), 

Sargassum communities (Chapter B.3.1.1.8), chemosynthetic and nonchemosynthetic deepwater benthic 

communities (Chapters B.3.1.1.9 and B.3.1.1.10, respectively), and soft bottom benthic communities 

(Chapter B.3.1.1.11) chapters.

Phase 2—Offshore Spill

With the initiation of a catastrophic blowout incident, an explosion and subsequent fire are assumed 

to occur. If a blowout associated with the drilling of a single exploratory well occurs, this could result in 

a fire that would burn for 1 or 2 days, but if a blowout occurs on a production platform and other wells 

feed the fire, it could burn for over a month. The drilling rig or platform may sink, and if this occurs in 

shallow water, the sinking rig or platform may land in the immediate vicinity. If the blowout occurs in 

deep water, the rig or platform could land a great distance away and could be beyond avoidance zones. 

Regardless of water depth, the immediate response would be from search and rescue vessels and aircraft, 

such as USCG cutters, helicopters, rescue planes, and firefighting vessels.

Early life stages of animals are usually more sensitive to oil than adults (Boesch and Rabalais, 1987; 

NRC, 2005). Weathered crude oil has been shown in laboratory experiments to cause malformation, 

genetic damage, and even mortality at low levels in fish embryos of Pacific herring (Carls et al., 1999). 

Because natural crude oil found in the Gulf of Mexico would generally float on the surface, fish species 

whose eggs and larvae are found at or near the water surface are most at risk from an offshore spill. 

Species whose spawning periods coincide with the timing of the highest oil concentrations would be at 

greatest risk.

Adult fish may be less at risk than earlier life stages, in part because they are less likely to concentrate 

at the surface and may avoid contact with floating oil. The effects of oil on organisms can include direct 

lethal toxicity, sublethal disruption of physiological processes (internal lesions), the effects from direct 

coating by oil (suffocation by coating gills), incorporation of hydrocarbons in organisms (tainting or 

accumulation in the food chain), and changes in biological habitat (decreased dissolved oxygen) (Moore 

and Dwyer, 1974). The extent of the impacts of the oil would depend on the properties of the oil and the 

time of year of the event.

If there is a subsea catastrophic blowout, it is assumed dispersants would be used. Then there could 

be effects on multiple life history stages and trophic levels. There is limited knowledge of the toxicity of 
Catastrophic Spill Event Analysis B-73

dispersants mixed with oil to specific species or life stages of ichthyoplankton and the likely extent of 

mortality because the combination of factors is difficult to determine. The combined toxic effects of the 

oil and any dispersants that may be used would not be apparent unless a significant portion of a year-class 

is absent from next year’s fishery (e.g., shrimps, crabs, snapper, and tuna). The North Atlantic bluefin 

tuna is an example of a fish/fishery in the Gulf of Mexico that could be at risk to lose a year-class. It has 

a relatively narrow peak spawning period in April and May and floating eggs. A catastrophic blowout 

during the spring season could cause a negative effect to this population. The Gulf of Mexico is one of 

only two documented spawning grounds for the Atlantic bluefin tuna; the other is in the Mediterranean 

Sea and spawning is clustered in a specific type of habitat along the continental slope. While the western 

Atlantic stock has suffered and a long-term rebuilding plan has failed to revive the population or the 

fishery, NOAA made a determination on May 27, 2011, that Atlantic bluefin tuna did not warrant species 

protection under the ESA at that time. The NOAA does plan to revisit this decision by 2013 when more 

information will be available concerning any effects of the Deepwater Horizon explosion, oil spill, and 

response. In addition, a new stock assessment will be available from the International Commission for 

the Conservation of Atlantic Tunas.

An example of a catastrophic event in the CPA was modeled using OSRA (Appendix C, Tables C-4 

and C-5). Because fish occur throughout the GOM, it is assumed that some individuals would be 

contacted with oil. Specific habitats that are discussed with regards to the Western Planning Area OSRA 

example and in the Appendix are water quality (Chapter B.3.1.1.2), wetlands (Chapter B.3.1.1.4), 

seagrass communities (Chapter B.3.1.1.5), live bottoms (Chapter B.3.1.1.6), topographic features

(Chapter B.3.1.1.7), Sargassum communities (Chapter B.3.1.1.8), chemosynthetic and 

nonchemosynthetic deepwater communities (Chapters B.3.1.1.9 and B.3.1.1.10, respectively), and soft 

bottom benthic communities (Chapter B.3.1.1.11). 

Studies by USEPA, Office of Research and Development (2010) using representative species provide 

some indication of the relative toxicity of Louisiana sweet crude oil, dispersants, and oil/dispersant mixes. 

Bioassays were conducted using two Gulf species—a mysid shrimp (Amercamysis bahia) and a small 

estuarine fish, the inland silverside (Menidia beryllinina)—to evaluate the acute toxic effects of oil, eight 

dispersants, and oil/dispersant mixtures. In addition, USEPA used standard in vitro techniques using the 

same dispersants to (1) evaluate the acute toxicity on three cell lines over a range of concentrations and 

(2) evaluate the effects of these dispersants on androgen and estrogen function using human cell lines (to 

see if they are likely to disrupt hormonal systems). All dispersants showed cytotoxicity in at least one cell 

type at concentrations between 10 and 110 ppm. Results of the in vitro toxicity tests were similar to the 

whole animal tests. For all eight dispersants, for both species, the dispersants alone were less toxic than 

the dispersant/oil mixture. Louisiana sweet crude oil alone was determined to be more toxic to both the 

mysid shrimp and silverside fish than the dispersants alone. The results of the testing for disruption of 

androgen and estrogen function indicate that the dispersants do not show biologically significant 

endocrine activity via androgen or estrogen pathways (USEPA, Office of Research and Development, 

2010).

The GOM waters out to 100 fathoms (182 m; 600 ft) have EFH’s described and identified for 

managed species (GMFMC, 2005; USDOC, NOAA, 2009). There are Fisheries Management Plans for 

shrimp, red drum, reef fishes, coastal migratory pelagics, spiny lobsters, coral and coral reefs, and highly 

migratory species (GMFMC, 2004; USDOC, NOAA, 2009). These species could use the GOM for EFH 

at different life history stages. The Highly Migratory Species Fisheries Management Plan was recently 

amended to update EFH and Habitat Areas of Particular Concerns for the Atlantic bluefin tuna spawning 

area (USDOC, NOAA, 2009).

These EFH’s in the Gulf of Mexico are discussed in various chapters of this Appendix: water column 

(Chapter B.3.1.1.2); wetlands (Chapter B.3.1.1.4); seagrass communities (Chapter B.3.1.1.5), live 

bottoms (Chapter B.3.1.1.6); topographic features (Chapter B.3.1.1.7), Sargassum communities 

(Chapter B.3.1.1.8); chemosynthetic and nonchemosynthetic deepwater benthic communities (Chapters 

B.3.1.1.9 and B.3.1.1.10, respectively), and soft bottom benthic communities (Chapter B.3.1.1.11); these 

EFH’s are also summarized in Appendix D. There are current NTL’s (NTL 2009-G39 and NTL 

2009-G40) and stipulations that provide guidance and clarification of the regulations with respect to many 

of these biologically sensitive underwater features and areas and benthic communities, which are 

considered EFH.
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Plankton 

Open-water organisms, such as phytoplankton and zooplankton, are essential to the marine food web. 

They play an important role in regulating climate, contribute to marine snow, and are an important source 

of nutrients for mesopelagic and benthic habitats. Also, monthly ichthyoplankton collections over the 

years 2004-2006 offshore of Alabama have confirmed that peak seasons for ichthyoplankton 

concentrations on the shelf are spring and summer (Hernandez et al., 2010). If a catastrophic blowout

occurs in the spring and summer, it could cause greater harm to fish populations and not just individual 

fish. Therefore, an offshore oil spill would not only have an impact on these populations but also on the 

species that depend on them.

The microbial community can also be affected by an offshore oil spill. The microbial loop is an 

essential part of the marine ecosystem. Changes in the microbial community because of an oil spill could 

have significant impacts on the rest of the marine ecosystem. However, several laboratory and field 

experiments and observations have shown that impacts to planktonic and marine microbial populations 

are generally short lived and do not affect all groups evenly, and in some cases stimulate growth of 

important species (Gonzalez et al., 2009; Graham et al., 2010; Hing et al., 2011).

Phase 3—Onshore Contact

It is estimated that shoreline oiling would last 1-5 months from a shallow-water catastrophic spill 

event and 3-4 months from a deepwater catastrophic spill. It is estimated that there would be contact to 

the shoreline within 30 days of the spill for both shallow-water and deepwater spill locations. Though 

response methods would be monitored, there would also be some impact from these efforts on contacted 

coastal habitats. Further detail on this catastrophic OSRA run is contained in Appendix C. 

The life history of estuarine-dependent species involves spawning on the continental shelf; the 

transportation of eggs, larvae, or juveniles back to the estuary nursery grounds; and migration of the 

adults back to the sea for spawning (Deegan, 1989; Beck et al., 2001). Estuaries in the Gulf of Mexico 

are extremely important nursery areas and are considered EFH for fish and other aquatic life (Beck et al., 

2001). Oiling of these areas, depending on the severity, can destroy nutrient-rich marshes and erode 

coastlines that have been significantly damaged by recent hurricanes. 

The Gulf of Mexico supports a wide variety of finfish, and most of the commercial finfish resources 

are linked either directly or indirectly to the estuaries that ring the Gulf of Mexico. Darnell et al. (1983) 

observed that the density distribution of fish resources in the Gulf was highest nearshore off of the central 

Gulf Coast. For all seasons, the greatest abundance occurred between Galveston Bay and the mouth of 

the Mississippi River. Oyster beds could be damaged by freshwater diversions that release tens of 

thousands of cubic feet of freshwater per second for months in an effort to keep oil out of the marshes. 

Adult oysters survive well physiologically in salinities from those of estuarine waters (about 7.5 parts per 

thousand sustained) to full strength seawater (Davis, 1958). While oysters may tolerate small changes in 

salinity for a few weeks, a rapid decrease in salinity over months would kill oysters. In the event of a 

catastrophic oil spill, at least 1 year’s oyster production in the area receiving fresh water would be lost 

because of exposure to freshwater and/or oil.

Phase 4—Post-Spill, Long-Term Recovery and Response

In addition to possible small fish kills because of direct impacts (as described under Phases 2 and 3), a 

catastrophic spill could affect fish populations in the long term. Due to a catastrophic spill, a significant 

portion of a year class of fish could be absent from the following year’s fishery, reducing overall 

population numbers. However, sublethal impacts, especially for long-lived species (e.g., snapper and 

grouper), could be masked by reduced fishing pressure because of closures. In addition healthy fish 

resources and fishery stocks depend on ideal habitat (EFH) for spawning, breeding, feeding, and growth 

to maturity. There could be long-term effects to coastal habitats from buried or sequestered oil becoming 

resuspended after a disturbance. Thus, a catastrophic spill that affects these areas could result in longterm impacts, including destruction to a portion of their natural habitats.
Catastrophic Spill Event Analysis B-75

Overall Summary and Conclusion (Phases 1-4)

Depending on the type of blowout and the proximity of marine life to it, an eruption of gases and 

fluids may generate not only a toxic effect but also pressure waves and noise significant enough to injure 

or kill local biota and destroy habitat in the immediate vicinity (Phase 1). Adult fish may be less at risk 

than earlier life stages, in part because they are less likely to concentrate at the surface and may avoid 

contact with floating oil. Effects of oil on organisms can include direct lethal toxicity, sublethal 

disruption of physiological processes (internal lesions), the effects from direct coating by oil (suffocation 

by coating gills), incorporation of hydrocarbons in organisms (tainting or accumulation in the food chain), 

and changes in biological habitat (decreased dissolved oxygen) (Phase 2). Estuaries in the Gulf of 

Mexico are extremely important nursery areas and are considered EFH for fish and other aquatic life 

(Beck et al., 2001). Oiling of these areas, depending on the severity, can destroy nutrient-rich marshes 

and erode coastlines that have been significantly damaged by recent hurricanes (Phase 3). Due to a 

catastrophic spill, a significant portion of a year class of fish could be absent from the following year’s 

fishery, reducing overall population numbers. However, sublethal impacts, especially for long-lived 

species (e.g., snapper and grouper), could be masked by reduced fishing pressure because of closures 

(Phase 4).

B.3.1.18. Commercial Fisheries

Phase 1—Initial Event

The initial explosion and fire could endanger commercial fishermen in the immediate vicinity of the 

blowout. Although commercial fishing vessels in the area would likely aid in initial search-and-rescue 

operations, the subsequent fire could burn for over a month, during which time commercial vessels would 

be expected to avoid the area so as to not interfere with response activities. This could impact the 

livelihood and income of these commercial fishermen. The extent of the economic impact on the fishing 

community would depend largely on the season during which the blowout occurred, the depth of water in 

which it occurred, and its distance from shore.

Phase 2—Offshore Spill

The Gulf of Mexico is one of the largest producers of seafood in the continental United States. In 

2010 the Gulf of Mexico provided 40 percent of the commercial fishery landings in the continental U.S. 

(excluding Alaska), with over 1.5 billion pounds valued at nearly $670 million (USDOC, NMFS, 2012d). 

Various commercial species are fished from State waters through the Exclusive Economic Zone and are 

found throughout the water column as well as at the surface and near the seafloor. Commercial species 

occupy many different habitats throughout the area, and many commercial species occupy different 

habitats during different life stages. Most commercial species spend at least part of their life cycles in the 

productive shelf and estuarine habitat. In the event of a catastrophic offshore spill, it is assumed that a 

large quantity of oil would be released daily whether this spill occurred in State or Federal waters. 

Although the oil would generally float, it is also assumed that dispersants would be used preventing much 

of the oil from reaching the surface.

As an example of the areas that could be affected by such a catastrophic oil spill in the CPA, two 

OSRA model runs were performed using three different launch points as described in Chapter B.1.2.3. 

The resulting tables show conditional probabilities (expressed as percent chance) of an oil spill contacting 

resources in the GOM for each launch point and for each season, the condition being that a spill is 

assumed to have occurred at the given location. Because the commercial species are so widespread over 

the GOM, all of the tables are referenced (Appendix C, Tables C-4 and C-5). 

Oil that is not volatilized, dispersed, or emulsified by dispersants has the potential to affect finfish 

through direct ingestion of hydrocarbons or ingestion of contaminated prey. Finfish are, however, mobile 

and generally avoid adverse conditions. Less mobile species or planktonic larval stages are more 

susceptible to the effects of oil and dispersants.

Actual effects of any oil that is released and comes in contact with populations of commercially 

important species will depend on the API gravity of the oil, its ability to be metabolized by 

microorganisms, and the time of year of the spill. The effects on the populations will be at a maximum 

during the spawning season of any commercially important population, exposing larvae and juveniles to 
B-76 Central Planning Area Lease Sales 235, 241, and 247 EIS

oil. The effects on commercial species may also include tainting of flesh or the perception of tainting in 

the market. This can, depending on the extent and duration of the spill, affect marketability of 

commercial species.

Even though sensory testing may show no detectable oil or dispersant odors or flavors and the 

chemical test results could be well below the known levels of concern, NOAA Fisheries would be 

expected to close large portions of the Gulf of Mexico during a high-volume spill. This would be done as 

a precautionary measure to ensure public safety and to assure consumer confidence in Gulf seafood 

(USDOC, NMFS, 2010c. Up to 30-40 percent of the Gulf of Mexico’s Exclusive Economic Zone could 

be closed to commercial fishing as the spill continues and expands (USDOC, NMFS, 2010d). This area 

could represent 50-75 percent of the Gulf’s seafood production (Flynn, 2010). The size of the closure 

area may peak about 50 days into the spill and could persist another 2-3 months until the well is killed or 

capped and the remaining oil is recovered or dissipates. During this period, portions or all of individual 

State waters would also be closed to commercial fishing.

The economic impacts of closures on commercial fishing are difficult to predict because they are 

dependent on the season and would vary by fishery. If fishers cannot make up losses throughout the 

remainder of the season, a substantial part of their annual income would be lost. In some cases, 

commercial fishers will leave the industry and some may move to areas still open to fishing, but at a 

greater cost because of longer transit times. Marketing issues are also possible; even if the catch is 

uncontaminated, the public may lack confidence in the product. The duration of the public’s perception 

of seafood tainting is also difficult to predict and depends to some extent on the duration of the spill and 

public awareness of the spill.

Phase 3—Onshore Contact

Shoreline contact of oil is estimated to persist from 1 to 5 months in the event of a shallow-water 

catastrophic spill and for up to 6 months from a deepwater catastrophic spill. The OSRA probability 

tables show the conditional probabilities (expressed as percent chance) for a shoreline contact for each 

season, the condition being that a spill is assumed to have occurred at the given location. Further detail 

on this catastrophic OSRA run is contained in Appendix C. 

This scenario, depending on the season of occurrence, would cause disruption in commercial fishing

activity because many commercial fishermen operate inshore in State waters.

In addition to closures in Federal waters, portions of individual State waters would also be closed to 

commercial fishing. The economic impacts of closures on commercial fishing are complicated to predict 

because it is dependent on season and would vary by fishery. If fishers cannot make up losses in the 

remainder of the season, a substantial part of their annual income will be lost. In some cases, commercial 

fishers may move to areas still open to fishing, but at a greater cost because of longer transit times and, in 

some instances, additional license costs. Some commercial fishermen may also augment their income by 

aiding in the cleanup effort and/or renting the boats as vessels of opportunity.

Phase 4—Post-Spill, Long-Term Recovery and Response

The Gulf of Mexico is an important biological and economic area in terms of commercial seafood 

production and recreational fishing. Commercial fishermen in the Gulf of Mexico harvested over 

1.5 billion pounds of finfish and shellfish in 2010 (USDOC, NMFS, 2012d). The economic impacts of 

closures on commercial fishing are complicated to predict because the economic effects are dependent on 

season and would vary by fishery. If fishermen cannot make up losses by fishing the remainder of the 

season or by participating as contractors in the cleanup, a substantial part of their annual income could be 

lost and may force them out of the industry. While the commercial fishing industry of Texas did not 

sustain measurable direct or indirect economic effects following the 1979 Ixtoc I blowout and spill 

(Restrepo et al., 1982), there is a documented phenomenon that, long after an incident, the perception of 

tainted fish and shellfish from the impacted area persists (Keithly and Diop, 2001). Data regarding the 

duration of the negative perception of Gulf seafood following the Deepwater Horizon explosion, oil spill, 

and response are not yet available. It is reasonable to assume that a negative perception could impact the 

value of commercial fish resources for several seasons.
Catastrophic Spill Event Analysis B-77

Overall Summary and Conclusion (Phases 1-4)

The Gulf of Mexico is one of the largest producers of seafood in the continental United States. 

Various commercial species are fished from State waters through the Exclusive Economic Zone and are 

found throughout the water column. The primary economic impacts of oil spill on commercial fisheries

are the closure of State or Federal waters to fishing and the perception of seafood tainting by the market. 

Both of these factors are difficult to predict. Closures depend on the size, timing, depth of water, and 

location of the spill as well as the fishery involved. Perception depends on length of the spill and public 

perception. Both of these factors could affect the livelihood of the fishing community.

B.3.1.19. Recreational Fishing

Phase 1—Initial Phase

About 20 percent of the recreational fishing activity in the Gulf of Mexico occurs within 300 ft 

(91 m) of oil and gas structures (Hiett and Milon, 2002). Therefore, an explosion and fire could endanger 

recreational fishermen and divers in the immediate vicinity of the blowout, especially if the blowout is 

located close to shore. Recreational vessels in the area would likely aid in initial search-and-rescue 

operations but they would also be in danger during the explosion and subsequent fire. The subsequent 

fire could burn for up to a month, during which recreational vessels would be expected to avoid the area 

and to not interfere with response activities. It is also possible that recreational fishing could be impacted 

in areas beyond the immediate area of the event due to the perceptions of the public.

Phase 2—Offshore Spill

If a catastrophic spill were to occur, a substantial portion of ocean waters could be closed. For 

example, 88,522 square miles (mi2

) (229,271 square kilometers [km2]) were closed to recreational fishing

activity at the peak of the Macondo well oil spill. However, the majority of recreational fishing activity 

occurs fairly close to shore. Therefore, while the spill remains offshore, the impacts would be particularly 

felt with respect to fishing of offshore species such as king mackerel and red snapper (the impacts of a 

catastrophic spill on fish populations are discussed in Chapter B.3.1.17). The NOAA’s Center for 

Coastal Monitoring and Assessment (USDOC, NOAA, 2012a) provides a set of maps that display the 

locations in the Gulf of Mexico where certain fish species are prevalent. However, even while the spill 

remains offshore, there could be impacts to inshore recreational fishing due to misperceptions regarding 

the extent of the spill or due to concerns regarding the tainting of fish species. These misperceptions 

could also reduce tourism activity, which would impact tourism-based recreational fishing activity.

In 2011, the percent of each Gulf Coast State’s recreational fishing activity that occurred in State and 

Federal ocean waters combined (i.e., not inland waters) were as follows: Texas (6%); Louisiana (5%); 

Mississippi (2%); Alabama (42%); and West Florida (34%) (USDOC, NMFS, 2012e; Texas Parks and 

Wildlife Department, 2012). Chapter 4.1.1.20 of this Supplemental EIS provides a further breakdown of 

recreational fishing activity by state. Further detail on this catastrophic OSRA run is contained in 

Appendix C. 

Phase 3—Onshore Contact

If a catastrophic spill were to reach shore, there would likely be noticeable impacts to recreational 

fishing activity. Since most recreational fishing activity occurs fairly close to shore, there would be a 

number of direct impacts to angler activity due to the fishing closures that would likely arise. This is 

particularly true since anglers would find it more difficult to find substitute fishing sites in the case of a 

catastrophic spill. In 2011, the percent of each Gulf State’s recreational fishing activity that occurred 

inland were as follows: Texas (94%); Louisiana (95%); Mississippi (98%); Alabama (58%); and West 

Florida (66%) (USDOC, NMFS, 2012e; Texas Parks and Wildlife Department, 2012). The impacts to 

recreational fishing would also depend on the time of year of the spill. In 2011, 31 percent of angler trips 

in the Gulf occurred between January and April, 41 percent of angler trips occurred between May and 

August, and 28 percent of angler trips occurred between September and December (USDOC, NMFS, 

2012e). In addition, fishing tournaments are often scheduled for the summer months and would be 
B-78 Central Planning Area Lease Sales 235, 241, and 247 EIS

difficult to reschedule in the aftermath of a catastrophic spill. Further detail on this catastrophic OSRA

run is contained in Appendix C. 

There would also be various economic impacts along the recreational fishing supply chain. Gentner 

Consulting Group (2010) estimates that recreational fishing activity supports $9.8 million in direct 

expenditures and $23 million in total sales per day in the Gulf of Mexico. There could be further impacts 

if the fishing closures persisted long enough to affect purchases of boats and other durable fishing 

equipment. There could also be further impacts if the loss of opportunities for recreational fishing 

activity exacerbated the fall in tourism activity that would arise due to the spill.

Phase 4—Post-Spill, Long-Term Recovery and Response

The long-term impacts of a catastrophic spill on recreational fishing activity would primarily depend 

on the extent to which fish populations recover (refer to Chapter B.3.1.1.17 for more information). 

However, the longer term impacts of a spill on recreational fishing activity would also depend on the 

extent to which public perceptions of fish tainting can be assuaged. In addition, the longer-term impacts 

would depend on the extent to which the various firms that serve the recreational fishing industry would 

be able to weather the downturn in activity resulting from the spill.

Overall Summary and Conclusion (Phases 1-4)

Recreational fishing activity could be noticeably impacted in the event of a catastrophic spill. This is 

particularly the case if the spill reached shore or if the spill occurred during peak times and places of 

recreational fishing activity. The long-term impacts of a catastrophic spill would depend on the extent to 

which fish populations recover and the length of time it would take to convince the public that it was 

again safe to fish in the affected areas.

B.3.1.20. Recreational Resources

Phase 1—Initial Event

The most immediate impacts of a catastrophic spill would be on the recreational fishing and 

recreational diving activity in the vicinity of the blowout. About 20 percent of the recreational fishing 

activity and 90 percent of the recreational diving activity in the Gulf of Mexico from Alabama to Texas 

occurs within 300 ft (91 m) of oil and gas structures (Hiett and Milon, 2002). The impacts on recreational 

fishing and recreational diving would be greater the closer the blowout occurred to shore. The immediate 

response activities could also impact ocean-based recreational activity. Finally, there could be impacts to 

tourism activity since a catastrophic spill would likely receive a large amount of media attention.

Phase 2—Offshore Spill

While the spill is still offshore, there could be some ocean-dependent recreation that is affected (e.g., 

fishing, diving, and boating), as discussed above. In addition, there may be some effects due either to 

perceived damage to onshore recreational resources that has not yet materialized or to general hesitation 

on the part of travelers to visit the overall region because of the spill. A Congressional hearing into this 

matter (U.S. House of Representatives, 2010) provides a broad overview of some of the effects that were 

felt along the Gulf Coast subsequent to the Deepwater Horizon explosion, oil spill, and response. For 

example, a representative of Pinellas County estimated that this area had lost roughly $70 million in hotel 

revenue even though beaches in this area did not receive any oil damage. This type of effect could be due 

to misperceptions about the spill, uncertainty about the future of the spill, or concerns about whether a 

tourism experience will be affected even if the destination is only within close proximity to a spill.

As previously mentioned, recreational diving is one offshore recreational activity that would be 

particularly affected by a catastrophic oil spill. Further detail on this catastrophic OSRA run is contained 

in Appendix C. 
Catastrophic Spill Event Analysis B-79

Phase 3—Onshore Contact

A catastrophic spill has the potential to noticeably impact the Gulf Coast recreation and tourism

industries. The water-dependent and beach-dependent components of these industries would be 

particularly vulnerable. Environmental Sensitivity Indexes (ESI’s) provide overall measures of the 

sensitivity of a particular coastline to a potential oil spill. The ESI’s rank coastlines from 1 (least 

sensitive) to 10 (most sensitive). Marshes and swamps are examples of resources that have ESI’s of 10 

due to the extreme difficulty of removing oil from these areas; marsh and swamp areas are particularly 

prevalent in Louisiana. The ESI’s for beach areas generally range from 3 to 6, depending on the type of 

sand and the extent to which gravel is mixed into the beach area; beach areas are particularly prevalent in 

Texas, Mississippi, Alabama, and Florida. The ESI maps for any coastline along the Gulf of Mexico can 

be viewed using the National Oceanic and Atmospheric Administration’s ERMA mapping system 

(USDOC, NOAA, 2012b). The ESI maps also provide point indicators for recreational resources. 

A catastrophic spill would also raise a number of issues regarding recreational activity that is based 

on tourism. One important point is that a spill of the Deepwater Horizon’s dimensions can influence a 

much broader range of individuals and firms than can a smaller spill. For example, a small, localized spill 

may lead some travelers to seek substitute recreational opportunities in nearby areas. However, a large 

spill is more likely to dissuade travelers from visiting a broader economic region. Similarly, small- and 

mid-sized restaurant chains and hotels may be able to find other customers or to simply weather a smaller 

spill. However, a spill the size of the Deepwater Horizon is more likely to affect these types of firms 

since they are less able to diversify their customer base. These effects can be seen in the makeup of those 

who filed damage claims with BP (Gulf Coast Claims Facility, 2012); the Gulf Coast Claims Facility 

closed in early 2012 subsequent to preliminary court approval of a settlement program. For example, the 

bulk of the claims by individuals have been made in the food, beverage, and lodging sector and in the 

retail, sales, and service sector. Claims have also been made by individuals and firms in a broad range of 

geographic regions, many of which were not directly impacted by oil.

Murtaugh (2010) provides data on the change in hotel and sales tax receipts for individual Gulf Coast 

counties in the months immediately following the Deepwater Horizon explosion, oil spill, and response. 

During the summer of 2010, the spill caused substantial declines in hotel receipts in the following 

counties: Baldwin, Alabama (33.2% decline); Santa Rosa, Florida (24.8% decline); Okaloosa, Florida 

(24.1% decline); Walton, Florida (12.3% decline); and Bay, Florida (7.4% decline). However, coastal 

counties west of Baldwin, Alabama (as far west as St. Mary, Louisiana), generally experienced noticeable 

increases in hotel receipts. This was particularly true in Mobile, Alabama; Jackson, Mississippi; and in 

the coastal parishes of Louisiana. For example, in Louisiana, St. Mary, Terrebonne, and Lafourche 

Parishes each reported increases in hotel tax receipts of over 80 percent in the summer of 2010. These 

effects are likely due to the influx of oil-spill relief workers to these areas in the immediate aftermath of 

the Deepwater Horizon explosion, oil spill, and response. Overall sales tax receipts in counties from 

Baldwin, Alabama, eastward also generally fell during 2010, although to a lesser extent than hotel tax 

receipts. Sales tax receipts in counties and parishes west of Baldwin, Alabama, did not show as clear a 

pattern as did hotel tax receipts. For example, overall sales tax receipts fell by 12.5 percent in Hancock 

County (Mississippi), receipts were almost unchanged in Harrison County (Mississippi), and receipts 

increased by 8.3 percent in Orleans Parish (Louisiana). These results suggest that the impacts of a future 

catastrophic spill will be influenced by the structure of a particular county/parish’s recreational economy, 

as well as by the extent to which oil-spill-response activities will mitigate some of the negative impacts of 

the spill in certain areas.

There could also be effects on tourist activities in areas far away from the areas directly affected by 

oil. For example, in Texas subsequent to the Deepwater Horizon explosion, oil spill, and response, some 

tourists may have stayed away from Texas Gulf Coast beaches due to misperceptions regarding the extent 

to which these beaches were damaged due to the spill. Conversely, there may have been some 

substitution of beach visitation away from beaches in the eastern Gulf towards the beaches in Texas, 

which were farther from the spill. While it is difficult to quantify these effects, some anecdotal evidence 

regarding this substitution effect can be found in Pack (2010). Hotel occupancy data suggest that these 

two effects may have largely offset each other. Source Strategies Inc. (2010) reports that total hotel 

occupancy in the three metro regions in Texas closest to the Gulf Coast increased just 1.9 percent during 

the third quarter of 2010 compared with the third quarter of 2009. Further detail on this catastrophic 

OSRA run is contained in Appendix C. 
B-80 Central Planning Area Lease Sales 235, 241, and 247 EIS

Phase 4—Post-Spill, Long-Term Recovery and Response

The longer-term implications of a catastrophic event on tourism would depend on the extent to which 

any structural/ecological damage can be repaired and the extent to which economic mitigation actions 

would occur. The long-term implications of a catastrophic spill would also depend on the extent to which 

public confidence in the various components of the recreational and tourism economies can be restored. 

For example, restaurants in the region would be impacted to the extent to which they are perceived to use 

seafood products caught or raised in contaminated waters. Similarly, although beaches can be 

decontaminated not long after a spill has been stopped, lingering perceptions can be expected to 

negatively impact tourism even after a spill has ended.

Oxford Economics (2010) attempts to quantify these effects by analyzing the impacts of recent 

catastrophic events on recreational economies. For example, they analyzed the Ixtoc I well blowout and 

spill of 1979, the scale and nature of which was reasonably similar to the Macondo well blowout and spill 

of 2010. In this example, it took approximately 3 years for beaches to be cleaned and for recreational 

activity to return to similar levels as before the spill. They also looked at the Prestige oil spill of 2002 off 

the coast of Spain. Given the nature and size of that spill, recreational activity was able to return to prespill levels in approximately 1 year. Alaska’s tourism economy took approximately 2 years to recover 

from the Exxon Valdez spill.

Overall Summary and Conclusion (Phases 1-4)

A catastrophic spill can cause noticeable impacts to recreational resources such as beaches. A 

catastrophic spill can also have complex effects on recreational activity that depends on tourism. The 

longer-term implications of a catastrophic oil spill on tourism would depend on the extent to which any 

structural/ecological damage can be repaired, the extent to which economic mitigation actions would 

occur, and the speed at which public confidence in the various components of the affected recreational 

and tourism economies would be restored.

B.3.1.21. Archaeological Resources

Phase 1—Initial Event

Offshore Archaeological Resources

BOEM protects all known, discovered, and potentially historic and prehistoric archaeological 

resources on the OCS by requiring appropriate avoidance criteria as well as directives to investigate these 

resources. Onshore archaeological resources, prehistoric and historic sites, would not be immediately 

impacted during the initial phase of a catastrophic blowout because the distance of a blowout site from 

shore is at least 3 nmi (3.5 mi; 5.6 km). However, offshore catastrophic blowouts, when compared with 

spills of lesser magnitude, may initially impact multiple archaeological resources. Resources adjacent to 

a catastrophic blowout could be damaged by the high volume of escaping gas, buried by large amounts of 

dispersed sediments, crushed by the sinking of the rig or platform, destroyed during emergency relief well 

drilling, or contaminated by the hydrocarbons.

Based on historical information, over 2,100 potential shipwreck locations have been identified on the 

Gulf of Mexico OCS (USDOI, MMS, 2007). This number is a conservative estimate and is heavily 

weighted toward post-19th century, nearshore shipwrecks, where historic records documenting the loss of 

the vessels were generated more consistently. Of the 2,100 recorded wrecks, only 233 records were 

determined to have associated spatial data possessing sufficient accuracy for BOEM’s needs.

In certain circumstances, BOEM’s Regional Director may require the preparation of an 

archaeological report to accompany the exploration plan, development operations coordination document, 

or development and production plan, under 30 CFR § 550.194, and BSEE’s Regional Director may do 

likewise under 30 CFR § 250.194 if a potential wreck is encountered during operations. As part of the 

environmental reviews conducted for postlease activities, available information will be evaluated 

regarding the potential presence of archaeological resources within a CPA proposed action area to 

determine if additional archaeological resource surveys and mitigations are warranted. Having complete 

knowledge of seafloor resources before a spill occurs would enable responders to quickly plan 

countermeasures in a way that would minimize adverse effects occurring from the spill response.
Catastrophic Spill Event Analysis B-81

Phase 2—Offshore Spill

Offshore Archaeological Resources

Due to the response methods (i.e., subsea dispersants) and magnitude of the response (i.e., thousands 

of vessels), a catastrophic blowout and spill have a greater potential to impact offshore archaeological 

resources than other accidental events.

Deep Water

In contrast to smaller spills or spills in shallow water, large quantities of subsea dispersants could be 

used for a catastrophic subsea blowout in deep water. This could result in currently unknown effects from 

dispersed oil droplets settling to the seafloor. Though information on the actual impacts to submerged 

cultural resources is inconclusive at this time, oil settling to the seafloor could come in contact with 

archaeological resources. At present, there is no evidence of this having occurred. A recent experimental 

study has suggested that, while the degradation of wood in terrestrial environments is initially retarded by 

contamination with crude oil, at later stages, the biodeterioration of wood was accelerated (Ejechi, 2003). 

While there are different environmental constraints that affect the degradation of wood in terrestrial and 

waterlogged environments, soft-rot fungal activity, one of the primary wood degrading organisms in 

submerged environments, was shown to be increased in the presence of crude oil. There is a possibility 

that oil from a catastrophic blowout could come in contact with wooden shipwrecks and artifacts on the 

seafloor and accelerate their deterioration.

Ancillary damages from vessels associated with oil-spill-response activities (e.g., anchoring) in deep 

water are unlikely because of the use of dynamically positioned vessels responding to a deepwater

blowout. If response and support vessels were to anchor near a deepwater blowout site, the potential to 

damage undiscovered vessels in the area would be high because of the required number and the size of 

anchors and the length of mooring chains needed to safely secure vessels. Additionally, multiple offshore 

vessel decontamination stations would likely be established in shallow water outside of ports or entrances 

to inland waterways, as seen for the Deepwater Horizon explosion, oil spill, and response. The anchoring 

of vessels could result in damage to both known and undiscovered archaeological sites; the potential to 

impact archaeological resources increases as the density of anchoring activities in these areas increases.

Shallow Water 

The potential for damaging archaeological resources increases as the oil spill and related response 

activities progress landward. In shallower waters, most of the damage would be associated with oil 

cleanup and response activities. Thousands of vessels would respond to a shallow-water blowout and 

would likely anchor, potentially damaging both known and undiscovered archaeological sites. Additional 

anchoring would be associated with offshore vessel decontamination stations, as described above. As the 

spill moves into the intertidal zone, the chance of direct contact between the oil and archaeological 

resources increases. As discussed above, this could result in increased degradation of wooden shipwrecks 

and artifacts.

Additionally, in shallower waters, shipwrecks often act as a substrate to corals and other organisms, 

becoming an essential component of the marine ecosystem. These organisms often form a protective 

layer over the shipwreck, virtually encasing the artifacts and hull remains. If these fragile ecosystems 

were destroyed as a result of the oil spill and the protective layer was removed, the shipwreck would then 

be exposed to increased degradation until it reaches a new level of stasis with its surroundings.

Regardless of water depth, because oil is a hydrocarbon, heavy oiling could contaminate organic 

materials associated with archaeological sites, resulting in erroneous dates from standard radiometric 

dating techniques (e.g., 14C-dating). Interference with the accuracy of 14C-dating would result in the loss 

of valuable data necessary to understand and interpret the sites.
B-82 Central Planning Area Lease Sales 235, 241, and 247 EIS

Phase 3—Onshore Contact

Onshore Archaeological Resources

Regardless of the water depth in which the catastrophic blowout occurs, it is assumed that more than 

1,000 mi (1,609 km) of shoreline could be oiled to some degree. Onshore prehistoric and historic sites 

would be impacted to some extent by a high-volume spill from a catastrophic blowout that reaches shore. 

According to Louisiana State Archaeologist Charles McGimsey, sites on barrier islands could suffer the 

heaviest impact. A few prehistoric sites in Louisiana, located inland from the coastline in the marsh and 

along bayous, could experience some light oiling. As discussed above, impacts would include the loss of 

ability to accurately date organic material from archaeological sites because of contamination or increased 

research costs to clean samples for analysis. Efforts to prevent coastal cultural resources from becoming 

contaminated by oil would likely be overwhelmed in the event of a hurricane and by the magnitude of 

shoreline impacted. The most significant damage to archaeological sites could be related to cleanup and 

response efforts. Fortunately, important lessons were learned from the Exxon Valdez spill in Alaska in 

1989, in which the greatest damage to archaeological sites was related to cleanup activities and looting by 

cleanup crews rather than from the oil itself (Bittner, 1996). As a result, cultural resources were 

recognized as significant early in the response, and archaeologists are, at present, embedded in Shoreline 

Cleanup Assessment Teams (SCAT) and are consulting with cleanup crews. Historic preservation 

representatives are present at both the Joint Incident Command as well as each Area Command under the 

general oversight of the National Park Service to coordinate response efforts (Odess, official 

communication, 2010). Despite these efforts, some archaeological sites suffered damage from looting or 

from spill cleanup activities (most notably the parade ground at Fort Morgan, Alabama) (Odess, official

communication, 2011).

Phase 4—Post-Spill, Long-Term Recovery and Response

Onshore Archaeological Resources

Regardless of the water depth in which the catastrophic blowout occurs, it is assumed that more than 

1,000 mi (1,609 km) of shoreline could be oiled to some degree. Onshore prehistoric and historic sites 

would be impacted to some extent by a high-volume spill from a catastrophic blowout that reaches shore. 

A few prehistoric sites in Louisiana, located inland from the coastline in the marsh and along bayous, 

could experience some light oiling. As discussed above, impacts would include the permanent loss of 

ability to accurately date organic material from archaeological sites because of contamination. As 

discussed above, the most significant damage to archaeological sites could be related to cleanup and 

response efforts. Long-term recovery would prove difficult if not impossible. Historic structures such as 

coastal forts that are exposed to oiling are generally constructed of brick or other porous, friable materials 

that are difficult to clean without causing further damage (Chin and Church, 2010). Funding for any sort 

or archaeological recovery is problematic outside of Federal lands because of existing laws and 

regulations. Most coastal prehistoric sites in Louisiana, for example, are on private lands where there is 

no mechanism to recover damages. Section 106 of the National Historic Preservation Act is triggered by 

a Federal action, which in the case of a spill, would be the response and not the actual spill. The Natural 

Resource Damage Assessment (NRDA) process codified by the Oil Pollution Act of 1990 is a legal 

process to determine the type and amount of restoration needed to compensate the public for harm to 

natural resources that occurs as a result of an oil spill, but it does not cover cultural, archaeological, or 

historic properties.

Overall Summary and Conclusion (Phases 1-4)

Archaeological resources are finite, unique, irreplaceable, nonrenewable records of mankind’s past, 

which, once destroyed or damaged, are gone forever. In the event of a catastrophic oil spill, the most 

likely source of irreversible impact is, ironically, from the spill response itself, and the danger increases 

dramatically as the response approaches the shoreline. This damage can, to a large extent, be mitigated 

by the early integration of archaeologists and State and Tribal historic preservation officers in the 

response to protect sites from impact. Mitigation of impacts from the oil itself are likely to meet with 

varied success depending upon the type of site and availability of funding.
Catastrophic Spill Event Analysis B-83

B.3.1.22. Land Use and Coastal Infrastructure

Phase 1—Initial Event

There would likely be no adverse impacts to land use and coastal infrastructure as a result of the 

events and the potential impact-producing factors that could occur throughout Phase 1 of a catastrophic 

spill event because of the long distance (>3 nmi; 3.5 mi; 5.6 km) from shore and the short duration of the 

initial event, fire, and/or explosion..

Phase 2—Offshore Spill

Impacts to tourism and recreational resources are addressed in Chapter B.3.1.20. Possible fisheries

closures are addressed in Chapters B.3.1.18 and B.3.1.19. As cleanup and remediation efforts evolve, 

there would be increased activity at ports and coastal cities, leading to increased traffic on road 

infrastructure and at port facilities. This follows from consideration of BOEM’s scenario estimates of up 

to 3,000 vessels, 25-50 planes/helicopters, and up to 25,000 workers for a shallow-water event and up to 

7,000 vessels, 50-100 planes/helicopters, and up to 50,000 workers for a deepwater event. Waste disposal

activities associated with boom deployment and retrieval would increase demand at waste disposal 

facilities. BOEM’s scenario estimates 5 million feet (1.5 million meters) of boom deployment and 

35,000 bbl of dispersant applied at the surface for a shallow-water event or 11 million feet (3.4 million 

meter) of boom deployment and 33,000 bbl of dispersant applied at the surface and 16,500 bbl of 

dispersant applied subsea for a deepwater event. Also, vessel decontamination sites would be set up 

offshore and the staffing/maintenance of these sites would contribute to increased activity at port facilities 

and traffic congestion on coastal waterways and highways.

Phase 3—Onshore Contact

In the event of a catastrophic spill, impacts on land use and infrastructure would be temporary and 

variable in nature. The scale of impact would depend on the nature of the event and whether it occurs in 

shallow or deep water. These impacts would include land use in staging areas, waste disposal locations 

and capacities, and potential delays because of vessel decontamination stations near ports, as described 

below.

For a shallow-water event, BOEM estimates 5-10 staging areas and 200-300 skimmers. For a 

deepwater event, scenario estimates call for 10-20 staging areas and 500-600 skimmers. Given these 

estimates and the several thousand responders that would be involved in the effort, BOEM expects a 

further increase in traffic congestion and some possible competing land-use issues near the staging areas, 

depending on the real estate market at the time of the event. Some infrastructure categories, such as 

vessels, ports, docks and wharves, would likely become very engaged in response activities and this could 

result in a shortage of space and functionality at infrastructure facilities if ongoing drilling activities were 

simultaneously occurring. However, if drilling were to be suspended, conflicting demands on 

infrastructure facilities would likely fail to materialize.

In the category of waste disposal, the impacts would be more visible as thousands of tons of oily 

liquid and solid wastes from the oil-spill cleanup would be disposed of in onshore landfills. As was the 

case in the Deepwater Horizon explosion, oil spill, and response, USEPA, in consultation with USCG, 

would likely issue solid-waste management directives to address the issue of contaminated materials and 

solid or liquid wastes that are recovered as a result of cleanup operations (USEPA, 2010c and 2010d). 

For navigation and port use, there would also be the potential for delays in cargo handling and slow 

vessel traffic because of decontamination operations at various sites along the marine transportation 

system (USDOT, 2010). However, vessel decontamination activities most likely would be complete 

within a year of the event, so impacts would be expected to be limited in duration.

Phase 4—Post-Spill, Long-Term Recovery and Response

Based on the rapid recovery of infrastructure that was heavily damaged by the catastrophic 2005 

hurricane season and the region’s experience in the few years since the Deepwater Horizon explosion, oil 

spill, and response, BOEM would not expect any long-term impacts to land use and coastal infrastructure 

as a result of a catastrophic oil-spill event. However, if a catastrophic oil spill were to occur, BOEM 
B-84 Central Planning Area Lease Sales 235, 241, and 247 EIS

would (as it is currently with regard to the Deepwater Horizon explosion, oil spill, and response) monitor 

the post-spill, long-term recovery phase of the event for any changes that indicate otherwise. A 

catastrophic spill could generate several thousand tons of oil-impacted solid materials disposed in 

landfills along the Gulf Coast. This waste may contain debris, beach, or marsh material (sand/silt/clay), 

vegetation, and personal protection equipment collected during cleanup activities. BOEM does not 

expect that landfill capacity would be an issue at any phase of the oil-spill event or the long-term 

recovery. In the case of the Deepwater Horizon explosion, oil spill, and response, USEPA reported that 

existing landfills receiving oil-spill waste had plenty of capacity to handle waste volumes; the Deepwater 

Horizon explosion, oil spill, and response’s waste that was disposed of in landfills represented less than 

7 percent of the total daily waste normally accepted at these landfills (USEPA, 2012).

It is not expected that any long-term, land-use impacts would arise from properties that are utilized 

for restoration activities and would somehow have their future economic use compromised. The rise or 

fall of property values would not be solely a function of some kind of economic impact from a 

catastrophic oil-spill event. There are many other factors that influence the value of property and its best 

economic use. To date, it is not clear from past experiences whether vegetation loss or erosion created by 

a spill could result in changes in land use. The amount and location of erosion and vegetation loss could 

be influenced by the time of year the spill occurs, its location, and weather patterns, including hurricane

landfalls.

Overall Summary and Conclusion (Phases 1-4)

There would likely be no adverse impacts to land use and coastal infrastructure throughout Phase 1 of 

a catastrophic spill event. Response efforts in Phases 2 and 3 would require considerable mobilization of 

equipment and people. While these efforts might temporarily displace traditional users of coastal land 

and infrastructure, these interruptions would not be long lasting. The post-spill, long-term recovery and 

response efforts during Phase 4 could generate several thousand tons of oil-impacted solid materials 

disposed in landfills along the Gulf Coast, but this would account for no more than 7 percent of the total 

daily waste normally accepted in these landfills. It is also not expected that any properties utilized for 

restoration activities throughout Phase 3 would not suffer any long-term land use or economic impacts.

B.3.1.23. Demographics

Phase 1—Initial Event

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter B.3.1.24). Since the impacts of a catastrophic spill on employment 

would take time to evolve, the initial impacts on demographics would be minimal. Therefore, there 

would likely be no adverse impacts to demographics as a result of the events and the potential impactproducing factors that could occur throughout Phase 1 of a catastrophic spill event.

Phase 2—Offshore Spill

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter B.3.1.24). For example, there could be some suspension of oil/gas 

activities in the immediate aftermath of the spill. This could cause some workers to seek employment 

outside of the OCS industry, for example in onshore oil/gas extraction or on overseas offshore projects. 

However, since the OCS oil and gas industry would likely eventually recover, the long-term impacts on 

demographics would be small. There could also be impacts on demographics if employment in 

recreation, tourism, or fishing industries were affected, due to either actual or perceived impacts of the 

spill. However, the impacts on these industries would become more acute if the spill were to reach shore.

Phase 3—Onshore Contact

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter B.3.1.24). For example, impacts to recreation/tourism and recreational 

and commercial fishing activities would become more acute if the spill were to reach shore. There would 

also be a larger presence of cleanup workers in some areas if the spill were to reach shore. For example, 
Catastrophic Spill Event Analysis B-85

48,200 workers were employed in response activities at the peak of the response effort following the 

Macondo well blowout and spill (RestoreTheGulf.gov, 2011). However, these impacts would be 

temporary and would be governed by the dynamics of the particular spill. There could also be impacts to 

demographics if there were impacts on the response workers’ health or if the demographics of the 

response workers were noticeably different from the local population.

Phase 4—Post-Spill, Long-Term Recovery and Response

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter B.3.1.24). The spill’s impacts on employment, and therefore 

demographics, would primarily be felt in the oil/gas, recreational fishing, commercial fishing, and 

recreation/tourism industries. However, it is unlikely that a catastrophic spill would cause substantial 

long-term changes to a region’s demographics. For example, the demographics data in Woods and Poole 

Economics, Inc. (2011) did not suggest large demographic changes to any Gulf regions subsequent to the 

Deepwater Horizon explosion, oil spill, and response. 

Overall Summary and Conclusion (Phases 1-4)

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter B.3.1.24). These impacts would likely be temporary and would be 

governed by the particular dynamics of the spill.

B.3.1.24. Economic Factors

Phase 1—Initial Event

The most immediate economic impacts of a catastrophic spill would be on the oil/gas production and 

employment associated with the area of the spill. There could also be impacts on commercial fishing

(Chapter B.3.1.18), recreational fishing (Chapter B.3.1.19), and recreational resources (Chapter 

B.3.1.20). However, the primary economic impacts of a catastrophic spill would depend how the spill 

evolves, which is discussed in subsequent sections.

Phase 2—Offshore Spill

In contrast to a less severe accidental event, suspension of some oil and gas activities would be likely 

following a catastrophic event. Depending on the duration and magnitude, this could impact hundreds of 

oil-service companies that supply the steel tubing, engineering services, drilling crews, and marine supply 

boats critical to offshore exploration. An interagency economic report estimated that the suspension 

arising from the Deepwater Horizon explosion, oil spill, and response may have directly and indirectly 

resulted in up to 8,000-12,000 fewer jobs along the Gulf Coast (USDOC, Economics and Statistics 

Administration, 2010). Greater New Orleans Inc. (2012) provides an overview of the impacts of 

decreased oil and gas industry operations subsequent to the Deepwater Horizon explosion, oil spill, and 

response. This report provides survey evidence regarding the various economic strains felt by businesses 

in Louisiana due to the Deepwater Horizon explosion, oil spill, and response. For example, this report 

found that 41 percent of the respondents were not making a profit due to the slowdown in operations. The 

economic impacts of a catastrophic spill would likely be more heavily concentrated in smaller businesses 

than in the larger companies due to their difficulty in finding substitute revenue sources. Much of the 

employment loss would be concentrated in coastal oil-service parishes in Louisiana (St. Mary, 

Terrebonne, Lafourche, Iberia, and Plaquemines Parishes) and counties/parishes where drilling-related 

employment is most concentrated (Harris County, Texas, in which Houston is located, and Lafayette 

Parish, Louisiana). There could also be economic impacts due to the impacts on commercial fishing

(Chapter B.3.1.18), recreational fishing (Chapter B.3.1.19), and recreational resources (Chapter 

B.3.1.20). 
B-86 Central Planning Area Lease Sales 235, 241, and 247 EIS

Phase 3—Onshore Contact

By the end of a catastrophic spill, a large number of personnel (up to 25,000 in the event of a shallowwater spill and up to 50,000 in the event of a deepwater spill) would be expected to have responded to 

protect the shoreline and wildlife and to cleanup vital coastlines. The degree to which new cleanup jobs 

offset job losses would vary greatly from county to county (or parish to parish). However, these new jobs 

would not make up for lost jobs, in terms of dollar revenue. In most cases, cleanup personnel are paid 

less (e.g., $15-$18 per hour compared with roughly $45 per hour on a drilling rig), resulting in consumers 

in the region having reduced incomes overall and thus, spending less money in the economy (Aversa, 

2010). In addition, the economic impacts of relief workers would likely vary by county or parish, causing 

noticeable positive economic impacts to some counties or parishes while having fairly small positive 

impacts in other counties or parishes (Murtaugh, 2010). However, the influx of relief workers could also 

cause some negative impacts if it disrupted some of the normal functioning of economies. In addition, if 

the spill reaches shore, the impacts to commercial fishing (Chapter B.3.1.18), recreational fishing

(Chapter B.3.1.19), and recreational resources (Chapter B.3.1.20) would likely be greater.

In the unfortunate event of a future disaster, the creation of a large financial claims administration 

process, similar to the Gulf Coast Claims Facility, would be likely. This administrative body would be 

responsible for distributing funds made available by the responsible party to parties financially hurt by the 

disaster. As demonstrated by the actions of Gulf Coast Claims Facility recipients following the 

Deepwater Horizon explosion, oil spill, and response, funds will likely be used by individuals to pay for 

necessities such as mortgages or groceries, while businesses who receive funds will likely use them to 

maintain payroll and current payments on equipment. As of March 2012, over $6 billion had been paid 

through the Gulf Coast Claims Facility, which mitigated some of the economic impacts of the Deepwater 

Horizon explosion, oil spill, and response (Gulf Coast Claims Facility, 2012).

Phase 4—Post-Spill, Long-Term Recovery and Response

While a catastrophic spill could immediately impact several Gulf Coast States for several months 

through fishing closures, loss of tourism, and any suspension of oil and gas activities, anticipating the 

long-term economic and employment impacts in the Gulf of Mexico is a difficult task. Many of the 

potentially affected jobs, like fishing charters, are self-employed. Thus, they would not necessarily file 

for unemployment and will not be included in business establishment surveys used to estimate State 

unemployment levels. In addition, unemployment numbers in states are based on nonagricultural jobs,

and the fishing industry is considered within the agriculture category. On the other side, it is also a 

challenge to estimate how many of these displaced workers have been hired to clean up the spill. For 

example, while thousands of vessels of opportunity would be active in the spill response, not all of these 

would be displaced commercial fishermen from the affected areas. The positive employment impacts 

related to response activities are likely to be shorter term than the negative impacts discussed above. 

However, the long-term economic impacts of a catastrophic spill will likely depend on the speed at which 

the oil/gas, commercial fishing, recreational fishing, and recreational industries recover.

Overall Summary and Conclusion (Phases 1-4)

There would be a number of economic impacts that would arise from a catastrophic oil spill. The 

most direct effects would be on the recreation/tourism, commercial fishing, and recreational fishing

industries that depend on damaged resources. There could also be substantial negative effects on the 

oil/gas industry due to moratoriums or rule changes that would arise. Finally, there could be substantial 

impacts due to the relief operations and economic mitigation activities that would occur in the aftermath 

of a catastrophic spill.

B.3.1.25. Environmental Justice

Phase 1—Initial Event

There would likely be no adverse impacts to environmental justice as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event 
Catastrophic Spill Event Analysis B-87

because of the long distance (>3 nmi; 3.5 mi; 5.6 km) from shore and the short duration of the initial 

event, fire, and/or explosion.

Phase 2—Offshore Spill

The environmental justice policy, based on Executive Order 12898 of February 11, 1994, directs 

agencies to incorporate into NEPA documents an analysis of potentially disproportionate and detrimental 

environmental and health effects of their proposed actions on minorities and low-income populations and 

communities. While the spill is still offshore, the primary environmental justice concern would be large 

commercial fishing closures disproportionately impacting minority fishers. In the event of a catastrophic 

spill, Federal and State agencies would be expected to close substantial portions of the Gulf to 

commercial and recreational fishing (USDOC, NOAA, 2010e). While oystering occurs “onshore,” oyster 

beds are also likely to be closed to harvests during Phase 2 of a catastrophic spill because of concerns 

about oil contamination and increased freshwater diversions to mitigate oil intrusion into the marshes. 

These closures would directly impact commercial fishermen and oystermen, and indirectly impact such 

downstream activities as shrimp processing facilities and oyster shucking houses. The mostly AfricanAmerican communities of Phoenix, Davant, and Point a la Hache in Plaquemines Parish, Louisiana, are 

home to families with some of the few black-owned oyster leases. Just as these leases have been 

threatened by freshwater diversion projects for coastal restoration, they could be threatened by Phase 2 of 

a catastrophic spill (Mock, 2010).

The Gulf of Mexico coast hosts multiple minority and low-income groups whose use of natural 

resources of the offshore and coastal environments make them vulnerable to fishing closures. While not 

intended as an inventory of the area’s diversity, we have identified several Gulf of Mexico coast 

populations of particular concern. An estimated 20,000 Vietnamese American fishermen and shrimpers 

live along the Gulf of Mexico coast; by 1990, over 1 in 20 Louisiana fishers and shrimpers had roots in 

Southeast Asia even though they comprised less than half a percent of the State’s workforce (Bankston 

and Zhou, 1996). Vietnamese Americans account for about one-third of all the fishermen in the central 

Gulf of Mexico (Ravitz, 2010). Islaños, African Americans, and Native American groups are also 

engaged in commercial fishing and oystering. Historically, Vietnamese Americans and African 

Americans have worked in the fish processing and oyster shucking industries. Shucking houses 

particularly, have provided an avenue into the mainstream economy for minority groups.

Therefore, fishing closures during Phase 2 of a catastrophic spill impacting the central Gulf of 

Mexico may disproportionately affect such minority groups as the Vietnamese Americans, Native 

Americans, African Americans, and Islaños (Hemmerling and Colten, 2003).

Phase 3—Onshore Contact

While most coastal populations along the Gulf of Mexico coast are not generally minority or low 

income, several communities on the coasts of St. Mary, Lafourche, Terrebonne, St. Bernard, and 

Plaquemines Parishes, Louisiana, have minority or low-income population percentages that are higher 

than their state average. These minority populations are predominately Native American, Islaños, or 

African American. For example, a few counties or parishes along the Gulf Coast have more than a 

2-percent Native American population (USDOI, MMS, 2007); about 2,250 Houma Indians (a State of 

Louisiana recognized tribe) are concentrated in Lafourche Parish, Louisiana, comprising 2.4 percent of 

the parish’s population, and about 800 Chitimacha (a federally recognized tribe) make up 1.6 percent of 

St. Mary Parish’s population. While these are not significant numbers on their own, viewed in the 

context of Louisiana’s overall 0.6 percent Native American average, these communities take on greater 

environmental justice importance.

Gulf Coast minority and low-income groups are particularly vulnerable to the coastal impacts of a 

catastrophic oil spill due to their greater than average dependence on the natural resources in the offshore 

and coastal environments. Besides their economic reliance on commercial fishing and oystering, coastal 

low-income and minority groups rely heavily on these fisheries and other traditional subsistence fishing, 

hunting, trapping, and gathering activities to augment their diets and household incomes (refer to 

Hemmerling and Colton, 2003, for an evaluation of environmental justice considerations for south 

Lafourche Parish). Regular commuting has continued this reliance on the natural resources of the coastal 
B-88 Central Planning Area Lease Sales 235, 241, and 247 EIS

environments even when populations have been forced to relocate because of landloss and the destruction 

from hurricane events.

State fishery closures because of a catastrophic oil spill could disproportionately affect minority and 

low-income groups. Shoreline impacts could generate additional subsistence-related effects. Therefore, 

these minority groups may be disproportionately affected if these coastal areas were impacted by a 

catastrophic spill and the resulting response.

Phase 4—Post-Spill, Long-Term Recovery and Response

After the spill is stopped, the primary environmental justice concerns relate to possible long-term 

health impacts to cleanup workers, a predominately minority population, and to possible disposal of oilimpacted solid waste in predominantly minority areas.

An analysis of socioeconomic characteristics shows that people of Cajun ethnicity in the Gulf Coast 

States are often found to be of a comparatively low socioeconomic status and to work jobs in the textile 

and oil industries (Henry and Bankston, 1999). Past studies suggest that a healthy offshore petroleum 

industry also indirectly benefits low-income and minority populations (Tolbert, 1995). One BOEMfunded study in Louisiana found income inequality decreased during the oil boom of the 1980’s and 

increased with the decline (Tolbert, 1995). If there is a suspension of oil and gas activities in response to 

a catastrophic spill, many oil- and gas-related service industries would attempt to avoid massive layoffs 

by cutting costs and deferring maintenance during the recovery. This was the case with the Deepwater

Horizon explosion, oil spill, and response, and the long-term impacts are still not fully understood.

Onshore and Offshore Cleanup Workers

By the end of a catastrophic spill, up to 25,000 (shallow water) or 50,000 (deepwater) personnel 

would be expected to be responding to the spill. The majority of these would be field responders (United 

Incident Command, 2010e). As seen by the Deepwater Horizon explosion, oil spill, and response, the 

racial composition of cleanup crews was so conspicuous that Ben Jealous, the president of the National 

Association for the Advancement of Colored People, sent a public letter to BP Chief Operations Officer 

Tony Hayward on July 9, 2010, demanding to know why African Americans were over-represented in 

“the most physically difficult, lowest paying jobs, with the most significant exposure to toxins” (National 

Association for the Advancement of Colored People, 2010). While regulations require the wearing of 

protective gear and only a small percentage of cleanup workers suffer immediate illness and injuries 

(Center for Disease Control and Prevention, 2010), exposure could have long-term health impacts (e.g., 

increased rates of some types of cancer) (Savitz and Engel, 2010; Kirkeleit et al., 2008). Aguilera et al. 

(2010) compiled and reviewed existing studies on the repercussions of spilled oil exposure on human 

health for patterns of health effects and found evidence of the relationship between exposure and “acute 

physical, psychological, genotoxic, and endocrine effects in the exposed individuals.” Acute symptoms 

from exposure to oil, dispersants, and degreasers include headaches, nausea, vomiting, diarrhea, sore 

eyes, runny nose, sore throat, cough, nose bleeds, rash, blisters, shortness of breath, and dizziness 

(Sathiakumar, 2010). The USEPA’s monitoring data have not shown that the use of dispersants during 

the Deepwater Horizon explosion, oil spill, and response resulted in a presence of chemicals that 

surpassed human health benchmarks (Trapido, 2010). The potential for the long-term human health 

effects are largely unknown. However, the National Institute of Environmental Health Sciences is 

conducting a study known as the “Gulf Long-Term Follow-Up Study” that should provide a better 

understanding of the long-term and cumulative health impacts, such as the consequences of working close 

to a spill and of consuming contaminated seafood. The “Gulf Long-Term Follow-up Study” will monitor 

oil-spill cleanup workers for 10 years and represents a national effort to determine if the Gulf oil spill led 

to physical or mental health problems (U.S. Dept. of Health and Human Services, NIEHS, 2010). The 

study has a target goal of 55,000 participants. As of October 2012, the National Institute of 

Environmental Health Sciences announced that over 29,000 cleanup workers and volunteers have 

enrolled in the “Gulf Long-Term Follow-up Study” (U.S. Dept. of Health and Human Services, NIEHS, 

2012). Prior research on post-spill cleanup efforts found that the duration of cleaning work was a risk 

factor for acute toxic symptoms and that seamen had the highest occurrence of toxic symptoms compared 

with volunteers or paid workers. Therefore, participants in the “Vessels of Opportunity” program, which 

recruited local boat owners (including Cajun, Houma Indian, and Vietnamese American fishermen) to 
Catastrophic Spill Event Analysis B-89

assist in cleanup efforts, would likely be one of the most exposed groups. African Americans are thought 

to have made up a high percentage of the cleanup workforce. The Occupational Safety and Health 

Administration (OSHA) released two matrices of gear requirements for onshore and offshore Gulf 

operations that were organized by task (U.S. Dept. of Labor, OSHA, 2010a). Of past oil-spill workers, 

uninformed and poorly informed workers were at more risk of exposure and symptoms, demonstrating the 

importance of education and proper training of workers (Sathiakumar, 2010). Therefore, a catastrophic 

spill may disproportionately affect seamen and onshore workers such as Cajuns, Vietnamese Americans, 

Houma Indian, and African Americans.

Solid-Waste Disposal 

Following a catastrophic spill, environmental justice concerns arise related to the disposal of cleanuprelated wastes near minority and/or low-income communities (Schleifstein, 2010). It is estimated that a 

catastrophic spill could generate several thousand tons of oil-impacted solid materials that would be 

disposed in landfills along the Gulf Coast. While no new landfills would be built because of a

catastrophic spill, the use of existing landfills might exacerbate existing environmental justice issues. For 

example, Mobile, Alabama, and Miami, Florida, are majority minority urban centers with a majority of 

minority residents living within a 1-mi (1.6-km) radius of chosen landfills or liquid processing centers. 

While only a small percentage of Deepwater Horizon explosion, oil spill, and response waste was sent to 

these facilities—13 percent of the liquid waste to Liquid Environmental Solutions in Mobile and only 

0.28 percent of the total liquid waste to Cliff Berry in Miami—they may receive more from potential 

future spills. Disposal procedures for the Deepwater Horizon explosion, oil spill, and response involved 

sorting waste materials into standard “waste stream types” at small, temporary stations, and then sending 

each type to existing facilities that were licensed to dispose of them. The location of temporary sorting 

stations was linked to the location of containment and cleanup operations. Hence, future locations of any 

sorting stations are not predictable since they would be determined by the needs of cleanup operations. 

However, waste disposal locations were determined by the specializations of existing facilities and by 

contractual relationships between them and the cleanup and containment firms. Louisiana received about 

82 percent of the Deepwater Horizon explosion, oil spill, and response liquid waste recovered; of this, 

56 percent was manifested to mud facilities located in Venice in Plaquemines Parish, Louisiana, and to 

Port Fourchon in Lafourche Parish, Louisiana, and then transferred to a processing facility in Port Arthur, 

Texas. The waste remaining after processing was sent to deep well injection landfills located in Fannett 

and Big Hill, Texas. The sites located in Venice and Port Fourchon, Louisiana, and in Port Arthur, 

Fannett, and Big Hill, Texas, have low-minority populations, but a few of these areas have substantial 

poverty rates relative to State and parish/county means.

Overall Summary and Conclusion (Phases 1-4)

For Phase 1 (Initial Event) of a catastrophic spill, there would likely be no adverse impacts to 

minority and low-income communities because of the long distance (>3 nmi; 3.5 mi; 5.6 km) from shore, 

as well as the short duration of the initial event, fire, and/or explosion. The primary environmental justice

concerns during Phase 2 (Offshore Spill) would be large-scale fishing closures, oyster bed contamination 

and closures, and subsequent impacts to downstream activities such as shrimp processing facilities and 

oyster shucking houses. These may disproportionately affect such minority groups as the Vietnamese 

Americans, Native Americans, African Americans, and Islaños. Phase 3 (Onshore Contact), depending 

on the location, could result in disproportional impacts to those groups that rely heavily on oystering, 

commercial fishing, and other traditional subsistence fishing, hunting, trapping, and gathering activities to 

augment their diets and household incomes. During Phase 4 (Post-Spill, Long-Term Recovery and 

Response), the primary environmental justice concerns relate to possible long-term health impacts to 

cleanup workers, a predominately minority population, and to the possible disposal of oil-impacted solid 

waste in predominantly minority areas. As in the case of the Deepwater Horizon explosion, oil spill, and 

response, understanding long-term impacts would be dependent on the outcome of ongoing research by 

various interested parties, such as the National Institutes of Health and BOEM. Overall, depending on a 

number of mainly geographic variables such as the location of fisheries closures and oyster bed 

contamination and closures, as well as the demographic composition of cleanup workers, and if waste 
B-90 Central Planning Area Lease Sales 235, 241, and 247 EIS

disposal was not distributed across the region at many different facilities, a catastrophic oil-spill event 

may have disproportionate effects on minority and low-income populations.

B.3.1.26. Species Considered due to U.S. Fish and Wildlife Service Concerns

Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout incident. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and 

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1 or 2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. The 

potential impacts reflect the explosion, subsequent fire for 1-30 days, and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well.

The scenarios for each phase, including cleanup methods, can be found Table B-4. 

BOEM has only focused on species within coastal counties and parishes because those are the species 

that could be potentially impacted by oil and gas development activities, including a potential OCS spill. 

There would likely be no adverse impacts to the species considered due to FWS concerns as a result of 

the events and the potential impact-producing factors that could occur throughout Phase 1 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements.

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. The 

potential impacts reflect spill and response in Federal and State offshore waters. Season and temperature 

variations can result in different resource impacts due to variations in oil persistence and oil and 

dispersant toxicity and because of differences in potential exposure of the resources throughout various 

life cycle stages.

There would likely be no adverse impacts to the species considered due to FWS concerns as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 2 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements.

Phase 3—Onshore Contact

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response and oil initially reaching the shoreline during the spill event or while the oil still persists in the 

offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. Re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 

contacted shore. The potential impacts reflect the spill and response in very shallow coastal waters and 

once along the shoreline. Season and temperature variations can result in different resource impacts due 

to variations in oil persistence and oil and dispersant toxicity and because of differences in potential 

exposure of the resources throughout various life cycle stages.

The FWS has explicitly communicated interest in specific species within State boundaries along the 

Gulf Coast. The species within Louisiana, Mississippi, Alabama, and Florida have been designated as 

endangered, threatened, candidate, listed with critical habitat, proposed nonessential experimental 

population, or distinct vertebrate population. The greatest threats to the majority of these species are the 
Catastrophic Spill Event Analysis B-91

loss of and/or modification to suitable habitat caused by urban and agricultural development. Further 

detail on this catastrophic OSRA run is contained in Appendix C. 

At this time, there is no known record of a hurricane crossing the path of a large oil spill; the impacts 

of such have yet to be determined. The experience from Hurricanes Katrina and Rita in 2005 was that the 

oil released during the storms widely dispersed as far as the surge reached (USDOC, NOAA, National 

Weather Service, 2012). Due to their reliance on terrestrial habitats to carry out their life-history 

functions at a considerable distance from the GOM, the activities of a CPA proposed action are unlikely 

to have significant adverse effects on the size and recovery of any of the FWS-mentioned species or 

populations in Texas, Louisiana, Mississippi, Alabama, and Florida. 

There would likely be no adverse impacts to the species considered due to FWS concerns as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 3 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements.

Phase 4—Post-Spill, Long-Term Recovery and Response

Phase 4 focuses on long-term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 

killed and cleanup activities are concluding. While it is assumed that the majority of spilled oil would be 

dissipated offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil 

has the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt 

marshes, oil may seep into the muddy bottoms. The potential impacts reflect long-term persistence of oil

in the environment and residual and long-term cleanup efforts.

As data continue to be gathered and impact assessments completed, a better characterization of the 

full scope of impacts to populations in the GOM from the Deepwater Horizon explosion, oil spill, and 

response will be available. Relevant data on the status of populations after the Deepwater Horizon

explosion, oil spill, and response may take years to acquire and analyze, and impacts from the Deepwater 

Horizon explosion, oil spill, and response may be difficult or impossible to discern from other factors. 

Therefore, it is not possible for BOEM to obtain this information within the timeline contemplated in this 

Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable 

information, BOEM’s subject-matter experts have used available scientifically credible evidence in this 

analysis and applied it using accepted methods and approaches. Nevertheless, a complete understanding 

of the missing information is not essential to a reasoned choice among alternatives for this Supplemental 

EIS. The CPA is an active oil and gas region with ongoing (or the potential for) exploration, drilling, and 

production activities. In addition, non-OCS energy-related activities will continue to occur in the CPA 

irrespective of a CPA proposed action (i.e., habitat loss and competition). The potential for effects from 

changes to the affected environment (post-Deepwater Horizon explosion, oil spill, and response), 

accidental spills (including low-probability catastrophic spills), and cumulative effects remains whether or 

not the No Action or an Action alternative is chosen under this Supplemental EIS.

There would likely be no adverse impacts to the species considered due to FWS concerns as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 4 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements.

Overall Summary and Conclusion (Phases 1-4)

Accidental blowouts, oil spills, and spill-response activities resulting from a CPA proposed action 

have the potential to impact small to large areas in the GOM, depending on the magnitude and frequency 

of accidents, the ability to respond to accidents, the location and date of accidents, and various 

meteorological and hydrological factors (including tropical storms). The incremental contribution of a 

CPA proposed action would not be likely to result in a significant incremental impact on the FWSmentioned species within the CPA; in comparison, non-OCS oil- and gas-related activities, such as 

habitat loss and competition, have historically proved to be of greater threat to the FWS-mentioned 

species.
B-92 Central Planning Area Lease Sales 235, 241, and 247 EIS

In conclusion, within the WPA, which is directly adjacent to the CPA, there is a long-standing and 

well-developed OCS Program (more than 50 years); there are no data to suggest that activities from the 

preexisting OCS Program are significantly impacting the FWS mentioned species populations; therefore, 

a CPA proposed action would be expected to have little or no effect on the FWS mentioned species.

B.4. PREPARERS

Darice Breeding, Physical Scientist

Brian Cameron, Environmental Scientist

Sindey Chaky, Social Scientist

Deborah Epperson, Biologist

Jeff Gleason, Biologist

Donald (Tre) W. Glenn III, Protected Species Biologist

Gary D. Goeke, Chief, Environmental Assessment Section

Chester Huang, Meteorologist

Jack Irion, Unit Supervisor, Marine Archaeologist, Social Sciences Unit

Mark D. Jensen, Economist

Brian Jordan, Archaeologist

Arie R. Kaller, Unit Supervisor, Environmental Scientist, Biological Sciences Unit

Harry Luton, Social Scientist

Lissa Lyncker, Unit Supervisor, Environmental Scientist, Environmental Assessment Section

Tershara Matthews, Unit Supervisor, Environmental Scientist, Environmental Assessment Section

Margaret Metcalf, Chief, Physical/Chemical Sciences Unit

Deborah H. Miller, Technical Editor

David P. Moran, Biologist

Maureen Mulino, Biologist

Michelle K Nannen, Biologist

Erin O’Reilly, Physical Scientist

James Sinclair, Biologist

B.5. REFERENCES

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Letters. Vol. 37. 5 pp. L18605, doi:10.1029/2010GL044689.

Aguilera, F., J. Méndez, E. Pásaro, and B. Laffon. 2010. Review on the effects of exposure to spilled 

oils on human health. Journal of Applied Toxicology 30:291-301. doi:10.1002/jat.1521.

Alabama State Port Authority. 2010. Spill continues to impact Gulf Coastal States, Port of Mobile will 

remain open. Media Update, July 2, 2010. Internet website: http://www.asdd.com/pdf/

ASPA_PortofMobile_OilSpillUpdate_07022010.pdf. Accessed November 10, 2011.

Alexander, S.K. and J.W. Webb. 1983. Effects of oil on growth and decomposition of Spartina 

alterniflora. In: Proceedings, 1983 Oil Spill Conference. . .February 28-March 3, 1983, San 

Antonio, TX. Washington, DC: American Petroleum Institute. Pp. 529-532.

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Catastrophic Spill Event Analysis B-117

Figure B-1. Location of Five Hypothetical Oil-Spill Launch Points for OSRA within the Study Area. (Spatial 

variability of the Loop Current is from Vukovich [2007] and is shown as percent of time that the Loop 

Current watermass is associated with a particular location.)
B-118 Central Planning Area Lease Sales 235, 241, and 247 EIS

Figure B-2. Spatial Frequency (%) of the Watermass Associated with the Loop Current in the Eastern Gulf of 

Mexico based on Data for the Period 1976-2003 (Vukovich, 2005).
Catastrophic Spill Event Analysis B-119

Figure B-3. Summary of Avian Species Collected by Date Obtained from the U.S. Fish and Wildlife Service as 

Part of the Deepwater Horizon Post-Spill Monitoring and Collection Process through May 12, 2011 

(USDOI, FWS, 2011b). (This figure represents the date the data were released and reported and 

does not represent the actual date individual birds were collected. Data on the Y-axis reflects the 

cumulative # of individual birds collected, identified, and summarized by date; data on the Z-axis 

reflects proportional change from one reporting date to the next. The data used in this figure are 

verified as per FWS’s QA/QC processes. The mean # of birds collected between intervals is 184.4 + 

89.3 SE [-807 min, 526 max for 13 collection intervals] and the mean % change between intervals is 

3.0 + 1.3% [-11.12% min., 8.27% max]. Unfortunately, we have no data on change in search effort 

temporally (or spatially) and also lack data prior to September 14, 2010; therefore, data at that point 

represent the baseline or “0” for determining interval differences. Disclaimer: All data should be 

considered provisional, incomplete, and subject to change. For more information, refer to FWS’s 

Weekly Bird Impact Data and Consolidated Wildlife Reports [USDOI, FWS, 2011b]; for additional 

information on the chronological change in number of birds collected, refer to Belanger et al., 2010).
B-120 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table B-1

Blowout Scenarios and Key Differences in Impacts, Response, and/or Intervention

Location of Blowout and Leak Key Differences in Impacts, Response, and/or Intervention

Blowout occurs at the sea surface 

(i.e., at the rig)

Offers the least chance for oil recovery because of the restricted access to the 

release point; therefore, greater impacts to coastal ecosystems. In addition to 

relief wells, there is potential for other intervention measures such as capping 

and possible manual activation of blowout-preventer (BOP) rams.

Blowout occurs along the riser 

anywhere from the seafloor to the 

sea surface. However, a severed 

riser would likely collapse, 

resulting in a leak at the seafloor.

In deep water, the use of subsea dispersants, if approved, may reduce impacts 

to coastal ecosystems; however, their use may increase exposure of deepwater 

marine resources to dispersed oil. There is a possibility for limited recovery of 

oil at the source. In addition to relief wells, there is potential for other 

intervention measures, such as capping and possible manual activation of BOP 

rams.

At the seafloor, through leak paths 

on the BOP/wellhead

In deep water, the use of subsea dispersant, if approved, may reduce impacts to 

coastal ecosystems; however, their use may increase exposure of deepwater

marine resources to dispersed oil.

With an intact subsea BOP, intervention may involve the use of drilling mud to 

kill the well. If the BOP and well stack are heavily compromised, the only 

intervention method may be relief wells. Greatest possibility for recovery of 

oil at the source, until the well is capped or killed.

Below the seafloor, outside the 

wellbore (i.e., broached)

Disturbance of a large amount of sediments resulting in the burial of benthic 

resources in the immediate vicinity of the blowout. The use of subsea 

dispersants would likely be more difficult (PCCI, 1999). Stopping this kind of 

blowout would probably involve relief wells. Any recovery of oil at the seabed 

would be very difficult.
Catastrophic Spill Event Analysis B-121

Table B-2

Properties and Persistence by Oil Component Group

Properties and

Persistence Light-Weight Medium-Weight Heavy-Weight

Hydrocarbon 

Compounds

Up to 10 carbon atoms 10-22 carbon atoms >20 carbon atoms

API o >31.1o 31.1o-22.3o <22.3o

Evaporation Rate Rapid (within 1 day) and 

complete

Up to several days; not 

complete at ambient 

temperatures

Negligible

Solubility in Water High Low (at most a few 

milligrams/liter)

Negligible

Acute Toxicity High because of 

monoaromatic 

hydrocarbons (BTEX)

Moderate because of 

diaromatic hydrocarbons 

(naphthalenes—2 ring 

PAH’s)

Low except because of 

smothering (i.e., heavier oils 

may sink)

Chronic Toxicity None, does not persist 

because of evaporation

PAH components (e.g., 

naphthalenes—2 ring 

PAH’s)

PAH components (e.g., 

phenanthrene, anthracene—

3 ring PAH’s)

Bioaccumulation 

Potential

None, does not persist 

because of evaporation

Moderate Low, may bioaccumulate 

through sediment sorption

Compositional 

Majority

Alkanes and cycloalkanes Alkanes that are readily 

degraded

Waxes, asphaltenes, and 

polar compounds (not 

significantly bioavailable or

toxic)

Persistence Low because of 

evaporation

Alkanes readily degrade, 

but the diaromatic 

hydrocarbons are more 

persistent

High; very low degradation 

rates and can persist in 

sediments as tarballs or 

asphalt pavements

API = American Petroleum Institute.

BTEX = benzene, ethylbenzene, toluene, and xylene

PAH = polycyclic aromatic hydrocarbon

Sources: Michel, 1992; Canadian Center for Energy Information, 2010.
B-122 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table B-3

Annual Volume of Produced Water Discharged by Depth

(millions of barrels)

Year Shelf

0-60 m

Shelf

60-200 m

Slope

200-400 m

Deepwater

400-800 m

Deepwater

800-1,600 m

UltraDeepwater

1,601-2,400 m

UltraDeepwater

>2,400 m

Total

2000 370.6 193.1 35.5 25.6 12.2 0.0 0.0 637.0

2001 364.2 185.2 35.0 32.0 16.6 0.0 0.0 633.0

2002 344.6 180.4 32.5 35.2 21.4 0.0 0.0 614.1

2003 359.4 182.9 31.2 39.0 35.5 0.2 0.0 648.2

2004 346.7 160.5 29.3 36.9 39.2 1.9 0.0 614.5

2005 270.1 113.5 23.1 33.5 43.0 5.8 0.0 489.0

2006 260.3 99.7 20.6 35.1 61.5 12.4 0.0 489.6

2007 307.0 139.4 22.2 40.0 70.3 15.5 0.1 594.5

2008 252.7 118.6 15.9 32.7 60.1 16.5 0.1 496.6

2009 263.9 108.3 19.9 39.2 65.3 25.0 0.1 521.7

Source: USDOI, BOEMRE, 2010b.
Catastrophic Spill Event Analysis

B-123

Table B-4 

Description of the Scenario for a Catastrophic Spill Event Occurring in Shallow Water or Deep Water 

(assumptions are described in detail in the text)

Scenario Shallow-Water Location Deepwater Location

Phase 1. Initial Event

Vertical Location of Blowout 4 possible locations including sea surface, along 

the riser, at the seafloor, and below the seafloor

4 possible locations including sea surface, along the riser, at 

the seafloor, and below the seafloor

Duration of Uncontrolled Fire 1-30 days 1-30 days

Phase 2. Offshore Spill

Duration of Spill 2-5 months 4-6 months

Rate of Spill 30,000 bbl per day* 30,000-60,000 bbl per day

Total Volume of spill (1) 0.9-3.0 MMbbl crude oil 2.7-7.2 MMbbl crude oil

10,000-20,000 bbl diesel fuel 

APIo Gravity Fresh oil will float (APIo >10) Fresh oil will float (APIo >10)

Characteristics of Oil Released Typical South Louisiana midrange paraffinic 

sweet crude oil 

Typical South Louisiana midrange paraffinic sweet crude 

oil; crude properties changed after oil traveled up the 

wellbore and passed through the water column, undergoing 

rapid depressurization and turbulence. Oil reached the 

surface as an emulsion stripped of many of its volatile 

components.

Response

Number of Vessels Up to 3,000 Up to 7,000

Number of Workers Up to 25,000 Up to 50,000

Number of Planes/Helicopters 25/50 50/100

Boom (million feet) 5 11

Dispersant Application

(surface application) (2)

35,000 bbl 33,000-bbl surface application and 16,500-bbl subsea 

application 

In-situ Burn Yes, will occur Yes, will occur

Vessel Decontamination Stations Yes Yes

Severe Weather The potential for severe weather is noted, which 

could temporarily halt containment and response 

efforts.

The potential for severe weather is noted, which could 

temporarily halt containment and response efforts.

Fisheries Closure During the peak, anticipate approximately 37% or 

88,522 mi2 (229,270 km2) closed to recreational and 

commercial fishing.
B-124 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table B-4. Description of the Scenario for a Catastrophic Spill Event Occurring in Shallow Water or Deep Water (assumptions are described in detail in 

the text) (continued). 

Scenario Shallow-Water Location Deepwater Location

Phase 3. Onshore Contact

Shoreline Oiling Duration 1-5 months 3-6 months

Response

Number of Staging areas 5-10 10-20

Number of Skimmers 200-300 500-600

Length of shoreline contacted

30 days1 = 0-50 miles2 30 days1 = 0-50 miles2

60 days = 50-100 miles 60 days = 50-100 miles

90 days = 100-1,000 miles 90 days = 100-1,000 miles

120 days = >1,000 miles 120 days = >1,000 miles 1 Not cumulative.

2 Length was extrapolated

Oil Characteristics and Appearance —Essentially stable emulsions mixed with sand.

—Typically initially stranded as surface layers and as 

discrete droplets/summer 2010.

Response Considerations for Sand 

Beaches

—No mechanical techniques allowed in some 

areas.

—Much of the beach cleanup conducted at night.

—Typically sand sieving, shaking, and sifting 

beach cleaning machines.

—Repetitive tilling and mixing using agriculture 

plows and discs in combination with beach 

cleaning machines.

—Sand washing treatment—sand sieve/shaker to 

remove debris and large oil particles and heated 

washing systems.

—Nearshore submerged oil difficult to recover 

and hard to locate; vacuums and snares could be 

used.

—No mechanical techniques allowed in some areas.

—Much of the beach cleanup conducted at night.

—Typically sand sieving, shaking, and sifting beach 

cleaning machines.

—Repetitive tilling and mixing using agriculture plows and 

discs in combination with beach cleaning machines.

—Sand washing treatment—sand sieve/shaker to remove 

debris and large oil particles and heated washing systems.

—Nearshore submerged oil difficult to recover and hard to 

locate; vacuums and snares could be used.

Response Considerations for Marshes —Lightly oiled—allowed to recovery naturally; 

degrade in place or removed by tidal or wave 

action.

—Moderately/heavily oiled—vacuumed or 

skimmed from boats possibly in conjunction with 

flushing; low-pressure flushing (with water 

comparable to marsh type); manual removal by 

—Lightly oiled—allowed to recovery naturally; degrade in 

place or removed by tidal or wave action.

—Moderately or heavily oiled—vacuumed or skimmed 

from boats possibly in conjunction with flushing; lowpressure flushing (with water comparable to marsh type); 

manual removal by hand or mechanized equipment; and 

vegetation cutting.
Catastrophic Spill Event Analysis

B-125

Table B-4. Description of the Scenario for a Catastrophic Spill Event Occurring in Shallow Water or Deep Water (assumptions are described in detail in 

the text) (continued). 

hand or mechanized equipment; and vegetation 

cutting.

—Heavily oiled areas—in-situ burning may be an 

option if water covers the sediment surface.

—Bioremediation may be utilized but mostly as a 

secondary treatment after bulk removal. 

—Heavily oiled areas—in-situ burning may be an option if 

water covers the sediment surface.

—Bioremediation may be utilized but mostly as a 

secondary treatment after bulk removal.

Response Considerations for 

Nearshore waters

Marsh areas—skimming and vacuum (in areas too 

shallow to use skimmers) systems used in 

conjunction with flushing, and booming to 

temporarily contain mobile slicks.

Marsh areas—skimming and vacuum (in areas too shallow 

to use skimmers) systems used in conjunction with flushing, 

and booming to temporarily contain mobile slicks.

Phase 4. Recovery Phase

Remaining Sources of Unrecoverable 

Weathered Oil

Buried or in surface pockets in coastal sand, 

sediment, or muddy bottoms and in pockets on the 

seafloor.

Buried or in surface pockets in coastal sand, sediment, or 

muddy bottoms and in pockets on the seafloor.

Oil Characteristics and Appearance As stranded oil weathered, some became buried through 

natural beach processes and appeared as surface residual 

balls (SRB) <10 cm (4 in) or as patties (SRP) 10 cm-1 m 

(4 in-3 ft).

Response Considerations for Sand 

Beaches, Marshes, and Nearshore 

Waters

See Phase 3 above. See Phase 3 above.

(1) A blowout may contain crude oil, natural gas, and condensate. Because the majority of environmental damage is due to the release of oil, this text 

assumes the spill to be an oil spill. However, a natural gas release would result in a less visible and less persistent adverse impact than an oil release.

(2) Subsea dispersal application must be individually approved.
B-126 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table B-5 

Birds Collected and Summarized by the U.S. Fish and Wildlife Service: 

Post-Deepwater Horizon Explosion, Oil Spill, and Response in the Gulf of Mexico1, 2

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4 Dead Alive Total Dead Alive Total Dead Alive Total

Amer. Coot Marsh/Wading 3 2 2 2 0 0 0 1 0 1 0.67

Amer. Oystercatcher Shorebird 13 7 3 7 3 0 3 1 3 3 0.54

Amer. Redstart Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Amer. White Pelican Seabird 19 5 3 8 4 0 4 4 8 7 0.42

Audubon’s Shearwater Seabird 36 1 1 1 35 0 35 0 2 0 0.03

Barn Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Barn Swallow Passerine 1 1 0 1 0 0 0 0 0 0 1.00

Belted Kingfisher Passerine 1 0 0 0 1 0 1 0 1 0 0.00

Bl.-crown. Night Heron Marsh/Wading 18 6 3 8 7 0 7 1 4 3 0.44

Black Skimmer Seabird 253 51 16 55 153 0 153 40 14 45 0.22

Black Tern Seabird 9 1 0 1 7 0 7 1 3 1 0.11

Bl.-bell. Whistl. Duck Waterfowl 2 0 0 0 0 0 0 0 2 2 0.00

Black-necked Stilt Shorebird 3 0 0 0 3 0 3 0 0 0 0.00

Blue-winged Teal Waterfowl 6 0 0 0 6 0 6 0 0 0 0.00

Boat-tailed Grackle Passerine 1 0 0 0 1 0 1 0 1 0 0.00

Broad-winged Hawk Raptor 1 0 0 0 1 0 1 0 1 0 0.00

Brown Pelican Seabird 826 152 227 339 248 0 248 177 149 239 0.41

Brown-headed Cowbird Passerine 1 0 0 0 0 0 0 0 1 1 0.00

Bufflehead Waterfowl 1 0 1 1 0 0 0 0 0 0 1.00

Canada Goose Waterfowl 4 0 1 1 1 0 1 1 2 2 0.25

Caspian Tern Seabird 17 7 3 8 4 0 4 2 6 5 0.47

Cattle Egret Marsh/Wading 36 4 4 7 25 0 25 3 4 4 0.19

Clapper Rail Marsh/Wading 120 27 5 29 64 0 64 20 14 27 0.24
Catastrophic Spill Event Analysis

B-127

Table B-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

Common Loon Diving 75 33 27 39 24 0 24 4 20 12 0.52

Common Moorhen Marsh/Wading 4 1 0 1 3 0 3 0 0 0 0.25

Common Nighthawk Passerine 1 0 0 0 0 0 0 0 1 1 0.00

Common Tern Seabird 25 15 12 16 9 0 9 0 0 0 0.64

Common Yellowthroat Passerine 2 0 0 0 2 0 2 0 0 0 0.00

Cooper’s Hawk Raptor 1 0 0 0 1 0 1 0 1 0 0.00

Cory’s Shearwater Seabird 4 0 0 0 3 0 3 0 1 1 0.00

Dbl-crest. Cormorant Diving 23 2 1 2 17 0 17 2 7 4 0.09

Eastern Kingbird Passerine 2 1 0 1 1 0 1 0 0 0 0.50

Eastern Meadowlark Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Eur. Collared-dove Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Eur. Starling Passerine 2 0 1 1 1 0 1 0 0 0 0.50

Forster’s Tern Seabird 40 17 8 20 12 0 12 6 7 8 0.50

Fulvous Whistl. Duck Waterfowl 1 0 0 0 0 0 0 0 1 1 0.00

Glossy Ibis Marsh/Wading 2 1 1 1 1 0 1 0 0 0 0.50

Great Blue Heron Marsh/Wading 42 5 3 6 26 0 26 4 16 10 0.14

Great Cormorant Diving 1 0 0 0 1 0 1 0 0 0 0.00

Great Egret Marsh/Wading 31 6 6 7 15 0 15 8 3 9 0.23

Great-horned Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Greater Shearwater Seabird 89 7 4 7 55 0 55 27 4 27 0.08

Green Heron Marsh/Wading 16 2 0 2 8 0 8 1 6 6 0.13

Gull-billed Tern Seabird 4 0 0 0 2 0 2 2 4 2 0.00

Herring Gull Seabird 31 10 11 13 10 0 10 2 13 8 0.42

House Sparrow Passerine 2 0 0 0 2 0 2 0 1 0 0.00

Killdeer Shorebird 3 0 0 0 3 0 3 0 0 0 0.00
B-128 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table B-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

King rail Marsh/Wading 1 0 0 0 0 0 0 0 1 1 0.00

Laughing Gull Seabird 2,981 1,025 355 1,182 1,390 0 1,390 304 371 409 0.40

Leach’s Storm-petrel Seabird 1 1 0 1 0 0 0 0 1 0 1.00

Least Bittern Marsh/Wading 4 0 0 0 4 0 4 0 2 0 0.00

Least Tern Seabird 106 46 7 49 43 0 43 12 3 14 0.46

Less. Bl.-backed Gull Seabird 4 1 1 1 1 0 1 1 2 2 0.25

Less. Scaup Waterfowl 1 0 0 0 0 0 0 1 0 1 0.00

Little Blue Heron Marsh/Wading 5 0 0 0 4 0 4 1 1 1 0.00

Long-bill. Dowitcher Shorebird 1 0 0 0 0 0 0 0 1 1 0.00

Magnif. Frigatebird Seabird 8 3 3 4 2 0 2 1 2 2 0.50

Mallard Waterfowl 26 5 4 6 16 0 16 0 7 4 0.23

Manx Shearwater Seabird 6 1 0 1 5 0 5 0 0 0 0.17

Masked Booby Seabird 9 4 3 4 1 0 1 0 4 4 0.44

Mottled Duck Waterfowl 6 0 0 0 5 0 5 1 1 1 0.00

Mourning Dove Passerine 15 3 1 3 8 0 8 0 6 4 0.20

Muscovy Duck Waterfowl 1 0 0 0 1 0 1 0 1 0 0.00

Neotropic Cormorant Diving 5 0 0 0 2 0 2 3 0 3 0.00

Northern Cardinal Passerine 3 0 0 0 3 0 3 0 0 0 0.00

Northern Gannet Seabird 475 225 189 297 99 0 99 30 107 79 0.63

Northern Mockingbird Passerine 5 0 0 0 4 0 4 0 2 1 0.00

Osprey Raptor 11 2 1 3 6 0 6 0 3 2 0.27

Pied-billed Grebe Diving 32 18 24 24 7 0 7 1 3 1 0.75

Piping Plover Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Purple Gallinule Marsh/Wading 2 0 0 0 2 0 2 0 0 0 0.00

Purple Martin Passerine 5 1 0 1 3 0 3 0 1 1 0.20
Catastrophic Spill Event Analysis

B-129

Table B-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

Red-breasted Merg. Waterfowl 2 1 1 1 1 0 1 0 1 0 0.50

Reddish Egret Marsh/Wading 2 1 1 1 1 0 1 0 1 0 0.50

Red-shouldered Hawk Raptor 1 0 0 0 0 0 0 0 1 1 0.00

Red-tailed Hawk Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Red-winged Blackbird Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Ring-billed Gull Seabird 2 0 1 1 1 0 1 0 0 0 0.50

Rock Dove (pigeon) Passerine 16 2 2 3 4 0 4 2 10 9 0.19

Roseate Spoonbill Marsh/Wading 15 7 3 7 3 0 3 5 1 5 0.47

Royal Tern Seabird 289 116 66 149 104 0 104 19 47 36 0.52

Ruddy Duck Waterfowl 1 1 0 1 0 0 0 0 0 0 1.00

Ruddy Turnstone Shorebird 13 1 3 3 8 0 8 1 5 2 0.23

Sanderling Shorebird 26 4 2 4 20 0 20 1 6 2 0.15

Sandwich Tern Seabird 70 28 20 34 25 0 25 8 14 11 0.49

Seaside Sparrow Passerine 9 4 0 4 5 0 5 0 0 0 0.44

Semipalm. Sandpiper Shorebird 3 2 1 3 0 0 0 0 0 0 1.00

Short-bill. Dowitcher Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Snowy Egret Marsh/Wading 22 12 9 14 6 0 6 2 3 2 0.64

Sooty Shearwater Seabird 1 0 0 0 0 0 0 0 1 1 0.00

Sooty Tern Seabird 3 0 1 1 2 0 2 0 1 0 0.33

Sora Marsh/Wading 5 2 1 2 1 0 1 2 0 2 0.40

Spotted Sandpiper Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Surf Scoter Waterfowl 1 1 1 1 0 0 0 0 0 0 1.00

Tri-colored Heron Marsh/Wading 31 9 5 11 7 0 7 11 2 13 0.35

Virginia Rail Marsh/Wading 3 0 0 0 3 0 3 0 1 0 0.00

White Ibis Marsh/Wading 7 1 1 1 4 0 4 2 3 2 0.14
B-130 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table B-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

White-tail. Tropicbird Seabird 1 0 0 0 1 0 1 0 0 0 0.00

White-wing. Dove Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Willet Shorebird 13 2 1 3 8 0 8 1 3 2 0.23

Wilson’s Plover Shorebird 3 0 0 0 2 0 2 1 0 1 0.00

Yellow-billed Cuckoo Passerine 2 2 0 2 0 0 0 0 0 0 1.00

Yel.-cr. Night Heron Marsh/Wading 9 1 0 1 7 0 7 0 3 1 0.11

Unid. Blackbird Passerine 1 0 0 0 0 0 0 0 1 1 0.00

Unid. Booby Seabird 1 0 0 0 1 0 1 0 1 0 0.00

Unid. Cormorant Diving 14 3 0 3 10 0 10 1 0 1 0.21

Unid. Dowitcher Shorebird 2 1 0 1 1 0 1 0 1 0 0.50

Unid. Duck Waterfowl 2 0 0 0 1 0 1 1 0 1 0.00

Unid. Egret Marsh/Wading 15 2 0 2 11 0 11 2 1 2 0.13

Unid. Flycatcher Passerine 1 1 0 1 0 0 0 0 0 0 1.00

Unid. Grebe Diving 4 2 1 2 2 0 2 0 0 0 0.50

Unid. Gull Seabird 248 79 1 80 134 0 134 33 4 34 0.32

Unid. Hawk Raptor 2 0 0 0 2 0 2 0 0 0 0.00

Unid. Heron Marsh/Wading 15 5 0 5 8 0 8 1 1 2 0.33

Unid. Loon Diving 7 2 2 4 3 0 3 0 1 0 0.57

Unid. Mockingbird Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Passerine Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Pelican Seabird 25 5 1 5 15 0 15 4 1 5 0.20

Unid. Pigeon Passerine 14 2 1 3 6 0 6 1 6 5 0.21

Unid. Rail Marsh/Wading 4 1 0 1 3 0 3 0 0 0 0.25

Unid. Raptor Raptor 1 0 0 0 1 0 1 0 0 0 0.00
Catastrophic Spill Event Analysis

B-131

Table B-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

Unid. Sandpiper Shorebird 2 0 0 0 2 0 2 0 2 0 0.00

Unid. Shearwater Seabird 6 0 0 0 5 0 5 1 0 1 0.00

Unid. Shorebird Shorebird 3 2 0 2 0 0 0 1 0 1 0.67

Unid. Skimmer Seabird 6 0 0 0 5 0 5 1 0 1 0.00

Unid. Sparrow Passerine 3 0 0 0 1 0 1 2 0 2 0.00

Unid. Swallow Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Tern Seabird 132 38 1 39 79 0 79 13 2 14 0.30

Unid. Warbler Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unknown spp. 593 51 2 53 451 0 451 88 1 89 0.09

Other 106 31 3 34 52 0 52 7 14 20 0.32

Column Totals 7,258 2,121 2,642 3,387 3,387 873 1,229 0.24 1 Data obtained from the U.S. Fish and Wildlife Service (FWS) as part of the Deepwater Horizon post-spill monitoring and collection process are summarized for May 12, 

2011 (USDOI, FWS, 2011). The data used in this table are verified as per FWS’s QA/QC processes. Disclaimer: All data should be considered provisional, incomplete, 

and subject to change (USDOI, FWS, 2011). For more information, refer to the Weekly Bird Impact Data and Consolidated Wildlife Reports. Numbers in this table have 

been verified against the original data from FWS’s website (USDOI, FWS, 2011). 2 As of May 12, 2011, 104 avian species had been collected and identified through the Deepwater Horizon post-spill monitoring and collection process (USDOI, FWS, 2011). 

Note: Though the process was triggered by the Deepwater Horizon explosion and oil spill, not all birds recovered were oiled (36% = oiled, 47% = unoiled, 17% = 

unknown), suggesting that “search effort” alone accounted for a large proportion of the total (n = 7,258) birds collected (Piatt et al., 1990a, page 127). Some of the live 

birds collected may have been incapable of flight due to age or molt, and some of the dead birds collected may have died due to natural mortality, predation, or other 

anthropogenic sources of mortality. The overall oiling rate across species including “others” and “unknowns” was 0.24 versus 0.25 for individuals identified to species. 

The oiling rate for the Top 5 (see bold rows in table) most-impacted avian species was 0.43 and included representatives only from the seabird group. These are listed in 

descending order based on the number collected: laughing gull (2,981 collected, 0.40 oiling rate); brown pelican (826 collected, 0.41 oiling rate); northern gannet 

(475 collected, 0.63 oiling rate); royal tern (289 collected, 0.52 oiling rate); and black skimmer (253 collected, 0.22 oiling rate). Note: There is a difference between the 

table structure here compared with the original table on FWS’s website. Herein, columns for live birds that later died were not included. Totals associated with each larger 

grouping are correct and sum to those column totals for the May 12, 2011, Collection Report values. Six new species or rows were added and 3 species were removed 

between the December 14, 2010, Collection Report (USDOI, FWS, 2010) and the May 12, 2011, Collection Report (USDOI, FWS, 2011). The major difference in number 

(-807) between the more recent and older versions was due to an ~10% overestimate in the previous report representing live birds that later died, as these individuals were 

counted twice in the December 14, 2010, Collection Report (USDOI, FWS, 2010). 3 For additional information on oiling rates by Species Group and additional statistics, refer to Table 4-12 of the 2012-2017 WPA/CPA Multisale EIS.
B-132 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table B-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service Post-Deepwater Horizon Explosion, Oil Spill, and Response in the Gulf 

of Mexico1, 2 (continued).

4 Oiling Rate: For each species, an oiling rate was calculated by dividing the “total” number of oiled individuals (∑ alive + dead) /∑ of total individuals collected for a given 

species/row. In general, it has been well documented that the number of birds collected after a spill event represents a small fraction of the total oiled population (direct 

mortality) due to various factors: species-specific differences in vulnerability to spilled oil, species-specific differences in distribution, habitat use and behavior; speciesspecific differences in abundance; species-specific differences in carcass deposition rates, persistence rates, and detection probabilities; overall search effort and temporal 

and spatial variation in search effort; and carcass loss due to predation, habitat, weather, tides, and currents (Piatt et al., 1990a and 1990b; Ford et al., 1996; Piatt and Ford, 

1996; Fowler and Flint, 1997; Flint and Fowler, 1998; Flint et al., 1999; Hampton and Zafonte, 2005; Ford, 2006; Castege et al., 2007; Ford and Zafonte, 2009; Byrd et al., 

2009; Flint et al., 2010). For example, Piatt and Ford (1996, Table 1) estimated a mean carcass recovery rate of only 17% for a number of previous oil-bird impact studies. 

Burger (1993) and Weise and Jones (2001) estimated recovery rates of 20% with the latter study based on a drift-block design to estimate carcass recovery rate from 

beached-bird surveys. Due to the fact that the coastline directly inshore of the well blowout location is primarily marsh and not sandy beaches, due to the distance from the 

blowout location to the coast, and due to predominant currents and wind directions during the event, the number of birds collected will likely represent a recovery estimate 

in the lower ranges of those provided in the literature to date (≤10%). A range of mortality estimates given the total number of dead birds collected through May 12, 2011, 

of 7,258 birds x recovery rates from the literature (0-59% in Piatt and Ford, 1996, Table 1) suggests a lower range of 12,302 birds* (59% recovery rate), an upper range of 

725,800 birds* (0% recovery rate), and 42,694 birds based on the 17% mean recovery rate from Piatt and Ford (1996). The lower range of estimates (i.e., high carcass 

recovery rates) is likely biased low because it assumes no search effort after May 2011 (i.e., no more birds were collected after that date) and does not account for any of the 

detection probability parameters that are currently unknown. The actual avian mortality estimate will likely not be available until the Natural Resource Damage Assessment 

(NRDA) process has been completed; this should include a combination of carcass drift experiments, drift-block experiments, corrections for carcass deposition and 

persistence rates, scavenger rates, and detection probability with additional modeling to more precisely derive an estimate. For additional information on oiling rates by 

Species Group and additional statistics, refer to Table 4-12 of the 2012-2017 WPA/CPA Multisale EIS. Note: Spill volume tends to be a poor predictor of bird mortality 

associated with an oil spill (Burger, 1993), though it should be considered for inclusion in any models to estimate total bird mortality, preferably with some metric of species 

composition and abundance (preferably density) pre-spill (Wilhelm et al., 2007).

* Corrected values are based on revisiting the original calculations after publication of the 2012-2017 WPA/CPA Multisale EIS. An additional estimate for total mortality 

based on Piatt and Ford (1996) is also provided.
Catastrophic Spill Event Analysis

B-133

Table B-6 

Federally Listed Avian Species Considered by State and Associated Planning Area in the Gulf of Mexico1

Species Status Critical Habitat IUCN Red List

Status2 States Planning Area

Red-cockaded Woodpecker Endangered No rules published Vulnerable AL, FL, LA, MS, TX WPA, CPA, EPA

Least Tern3 Endangered No rules published Least Concern AL, LA, TX (FL, MS) WPA, CPA, EPA

Piping Plover Threatened Designated Near Threatened AL, FL, LA, MS, TX WPA, CPA, EPA

Roseate Tern Threatened No rules published Least Concern FL only EPA

Wood Stork Endangered No rules published Least Concern AL, FL, MS CPA, EPA

Whooping Crane Endangered Designated Endangered TX, LA4, FL4 WPA, CPA, EPA

Mississippi Sandhill Crane Endangered Designated Not Yet Assessed MS only CPA

Attwater’s Prairie Chicken Endangered No rules published Not Yet Assessed TX only WPA

N. Aplomado Falcon Endangered No rules published Not Yet Assessed TX only WPA

Everglades Snail Kite Endangered Designated Not Yet Assessed FL only EPA

Cape Sable Seaside Sparrow Endangered Designated Not Yet Assessed FL only EPA

Audubon’s Crested Caracara Threatened No rules published Not Yet Assessed FL only EPA

Sprague’s Pipit Candidate NA – Priority 2 Vulnerable LA, TX WPA, CPA

Bald Eagle Delisted No rules published Least Concern AL, FL, LA, MS, TX WPA, CPA, EPA

Peregrine Falcon Delisted Designated Least Concern AL, FL, LA, MS, TX WPA, CPA, EPA

Eastern Brown Pelican Delisted No rules published Least Concern AL, FL, LA, MS, TX WPA, CPA, EPA

Red Knot Proposed Threatened NA – proposed threatened Least Concern FL, LA, TX WPA, CPA, EPA

1 Information contained in this table was obtained via an email attachment from the U.S. Fish and Wildlife Service (FWS) on April 6, 2012 (USDOI, FWS, 2012) and from 

FWS’s “Endangered Species” website and associated queries for “species” available from FWS’s website (USDOI, FWS, 2011c). Additional information for each species 

can be found at NatureServe Explorer (2011). Note: All species listed in this table are considered, but only the piping plover, roseate tern, whooping crane, wood stork, 

Mississippi sandhill crane, bald eagle, eastern brown pelican, and red knot will be analyzed. 2 International Union for Conservation of Nature (IUCN) – The Red List classifies species as imperiled (Critically Endangered, Endangered, or Vulnerable), not imperiled 

(Near Threatened or Least Concern), extinct (Extinct, Extinct in the Wild), or Data Deficient (Butchart et al., 2004 and 2005; Harris et al., 2012). If species meet the 

quantitative thresholds of any of the following criteria, they will be added to the Red List: (1) decline in population size; (2) small geographic range; (3) small population 

size plus decline; (4) very small population size; or (5) quantitative analysis. 3 The Interior population of the least tern was listed as endangered on May 28, 1985 (Federal Register, 1985) throughout much of its breeding range in the Midwest. This 

designation does not provide or extend Endangered Species Act (ESA) protection to the breeding population of Gulf Coast “population” of least terns. Similarly, ESA 

protection for breeding least terns only applies to certain segments or areas (inland rivers and lakes ~50 mi [80 km] inland) of Louisiana, Mississippi, and Texas. 4 The whooping crane is considered endangered throughout its range in the U.S. except where nonessential, experimental flocks have been established. More recently, a 

release site (White Lake Wetlands Conservation Area, Vermilion Parish) was added in Louisiana (Table 4-14 of the 2012-2017 WPA/CPA Multisale EIS) with a release of 

10 birds on February 22, 2011. To date, only 3 of the original 10 released cranes remain; an additional release of 16 cranes occurred on December 1, 2011. The Gulf Coast 

States that have these nonessential, experimental flocks include Alabama, Louisiana, Mississippi, and Florida; as well, wild whooping cranes may rarely occur as transients 

in Mississippi and Alabama, but they are not known to breed in either state. 5 The red knot is currently a proposed threatened species as of September 30, 2013 (Federal Register, 2013). 

APPENDIX C 

 

BOEM-OSRA CATASTROPHIC RUN

BOEM-OSRA Catastrophic Run C-3 

C. BOEM-OSRA CATASTROPHIC RUN 

A special Oil-Spill Risk Analysis (OSRA) run was conducted in order to estimate the impacts of a 

possible future catastrophic or high-volume, long-duration oil spill. Thus, assuming a hypothetical highvolume, long-duration oil spill occurred, this analysis emphasized modeling a spill that continued for 

90 consecutive days, with each trajectory tracked for up to 60 days. The analysis was conducted for the 

trajectories of oil spills from seven hypothetical spill locations to various onshore and offshore 

environmental resources. The probability of an oil spill contacting a specific resource within a given time 

of travel from a spill point is termed a conditional probability; the condition being that a spill is assumed 

to have occurred. Each trajectory was allowed to continue for as long as 60 days. However, if the 

hypothetical spill contacted shoreline sooner than 60 days after the start of the spill, the spill trajectory 

was terminated, and the contact was recorded. Although, overall OSRA is designed for use as a riskbased assessment, for this analysis, only the conditional probability, the probability of contact to the 

resource, was calculated. The probability of a catastrophic spill occurring was not calculated; thus, the 

combination of the probability of a spill and the probability of contact to the resources from the 

hypothetical spill locations were not calculated. Results from this trajectory analysis provide input to the 

final product by estimating where spills might travel on the ocean’s surface and what environmental 

resources might be contacted if and when another catastrophic spill occurs, but it does not provide input 

on the probability of another catastrophic spill occurring.

Catastrophic OSRA Run Methods

The OSRA model, originally developed by Smith et al. (1982) and enhanced by this Agency over the 

years (Ji et al., 2002, 2004a, 2004b, and 2011), simulates oil-spill transport using model-simulated winds 

and ocean currents in the Gulf of Mexico. An oil spill on the ocean surface is moved around by the 

complex surface ocean currents exerting a shear force on the spilled oil from below. In addition, the 

prevailing wind exerts an additional shear force on the spill from above, and the combination of the two 

forces causes the transportation of the oil spill away from its initial spill location. In the OSRA model, 

the velocity of a hypothetical oil spill is the linear superposition of the surface ocean current and the wind 

drift caused by the winds. The model calculates the movement of hypothetical spills by successively 

integrating time sequences of two spatially gridded input fields: the surface ocean currents and the sealevel winds. Thus, the OSRA model generates time sequences of hypothetical oil-spill locations—

essentially, oil-spill trajectories.

At each successive time step, the OSRA model compares the location of the hypothetical spills 

against the geographic boundaries of onshore and offshore environmental resources. Resource locations 

are the same as for the typical OSRA run. The frequencies of oil-spill contact are computed for 

designated oil-spill travel times (e.g., 3, 10, 30, or 60 days) by dividing the total number of oil-spill 

contacts by the total number of hypothetical spills initiated in the model from a given hypothetical spill 

location. The frequencies of oil-spill contact are the model-estimated probabilities of oil-spill contact. 

The OSRA model output provides the estimated probabilities of contact to resources from five launch 

points (LP) in the Western and Central Planning Areas (Figure C-1). 

The trajectories simulated by the OSRA model represent only hypothetical pathways of oil slicks; 

they do not involve any direct consideration of cleanup, dispersion, or weathering processes that could 

alter the quantity or properties of oil that might eventually contact the environmental resource locations. 

However, an implicit analysis of weathering and spill degradation can be considered by choosing a travel

time for the simulated oil spills when they contact environmental resource locations that represent the 

likely persistence of the oil slick on the water surface.

Oil spill runs with weathering were performed using the Spill Impact Model System (SIMAP) 

software (Applied Science Associates, Inc., 2012) in order to determine a reasonable length of time for 

simulating the trajectories for the catastrophic OSRA runs. Based on the SIMAP spill scenario runs, 

60 days was chosen as the longest spill travel time for the catastrophic OSRA runs. For each scenario 

run, SIMAP was used to simulate surface oil trajectories from input current and wind fields and 

weathering processes, including evaporation, dispersion, dissolution, and natural degradation. To 

compute the weathering assumption for the catastrophic OSRA run, 12 different scenarios were 

performed (1 in each season from 1993 through 1995), using a spill size of 60,000 bbl, a spill duration of 
C-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

24 hours, and a South Louisiana Crude (light) oil. Based on these runs, a conservative estimate of 

60 days was chosen as the length of time that oil would likely persist floating on the surface following a 

catastrophic spill. For comparison, 19 days was the calculated persistence time of Deepwater Horizon oil 

on the water’s surface (Chapter 3.2.1.5.4), and a 30-day catastrophic OSRA run has previously been used 

to simulate that particular spill event, which occurred in spring through early summer (Ji et al., 2011).

In the trajectory simulation portion of the OSRA model, many hypothetical oil-spill trajectories are 

produced by numerically integrating a temporally and spatially varying ocean current field, and 

superposing on that an empirical wind-induced drift of the hypothetical oil spills (Samuels et al., 1982). 

Collectively, the trajectories represent a statistical ensemble of simulated oil-spill displacements produced 

by a field of numerically derived winds and ocean currents. The winds and currents are assumed to be 

statistically similar to those that will occur in the Gulf during future offshore activities. In other words, 

the oil-spill risk analysts assume that the frequency of strong wind events in the wind field is the same as 

what will occur during future offshore activities. By inference, the frequencies of contact by the 

simulated oil spills are the same as what could occur from actual oil spills during future offshore 

activities.

Another portion of the OSRA model tabulates the contacts by the simulated oil spills. A contact to 

shore will stop the trajectory of an oil spill; no re-washing is assumed in this model. After specified 

periods of time, the OSRA model will divide the total number of contacts to the environmental resources 

by the total number of simulated oil spills from each of the LP’s. These ratios are the estimated 

probabilities of oil-spill contact from offshore activities at that geographic location, assuming spill 

occurrence.

Detailed information on ocean currents and wind fields is needed when conducting an oil-spill risk 

analysis (Ji, 2004). The ocean currents used are numerically computed from an ocean circulation model 

of the Gulf of Mexico driven by analyzed meteorological forces (the near-surface winds and the total heat 

fluxes) and observed river inflow into the Gulf of Mexico (Oey, 2005 and 2008). The models used are 

versions of the Princeton Ocean Model, which is an enhanced version of the earlier constructed MellorBlumberg Model.

The ocean model calculation was performed by Princeton University (Oey, 2005 and 2008). This 

simulation covered the 14-year period of 1993 through 2006, and the results were saved at 3-hour 

intervals. This run included the assimilation of sea-surface altimeter observations to improve the ocean 

model results. The surface currents were then computed for input into the OSRA model, along with the 

concurrent wind field. The OSRA model used the same wind field to calculate the empirical wind drift of 

the simulated spills. The statistics for the contacts by the trajectories forced by the currents and winds 

were combined for the average probabilities.

Trajectories of hypothetical spills were initiated every 1.0 day from each of the launch points over the 

14-year simulation period from January 1, 1993, to December 31, 2006. The chosen number of 

trajectories per site was small enough to be computationally practical and large enough to reduce the 

random sampling error to an insignificant level. Also, the weather-scale changes in the winds are at least 

minimally sampled, with simulated spills started every 1.0 day.

Five launch point locations (LP 1-5) were developed for the Western and Central Planning Areas. 

The locations were determined based on the approximate areas with the possibility of finding the largest 

oil volume within each planning area. The launch point locations are as follows:

Description Longitude (DD) Latitude (DD) Launch Point (LP)

Central Planning Area

(west of Mississippi River)

-92.17851 28.98660 1

Central Planning Area

(east of Mississippi River)

-88.15338 29.91388 2

Central Planning Area

(slope area)

-90.22203 27.31998 3

Western Planning Area

(shelf area)

-96.76627 27.55423 4

Western Planning Area

(slope area)

-94.51836 27.51367 5

DD = decimal degrees.
BOEM-OSRA Catastrophic Run C-5 

The methodology used for launch point selection is not part of the OSRA model in the manner it has 

been typically run for this Agency’s spill analyses. Gulf of Mexico OCS Region geologists and engineers 

used the following methodology to select launch point locations. BOEM’s Office of Resource Evaluation 

applied their Undiscovered Resource Distribution Methodology to identify a location within the proposed 

lease sale area where the potential for a large undiscovered oil volume may exist. For each geologic play, 

the undiscovered technically recoverable resource volume is distributed throughout the play using a 

statistical allocation process that is based on the likelihood of future oil discovery potential. The 

probability factors used to allocate undiscovered oil volumes to specific areas within the geologic play is 

based on the pool-density of existing discoveries, the density of undrilled prospects on leased acreage, 

and the results from recent exploration drilling activity. In areas where the potential for undiscovered 

technically recoverable resource volume exists for more than one geologic play, the oil volumes are 

aggregated. Results from the aggregation were used to identify geographic areas of high potential for 

future oil discoveries: three in the Central Planning Area and two in the Western Planning Area of the 

Gulf of Mexico. Although these areas may encompass hundreds of square miles, the coordinates for the 

five launch points were selected qualitatively to correspond with the centroid of these areas.

Catastrophic OSRA Results

Based on the weathering analyses (described above), OSRA model trajectories were analyzed up to 

60 days, and any spill contacts occurring during this elapsed time are reported in the probability tables 

(Tables C-1 through C-10). Conditional probabilities of contact with environmental resources within 60 

days of travel time were calculated for each of the hypothetical spill sites. The probability estimates were 

tabulated for the 60-day trajectories, as averages for the 14 years of the analysis from 1993 to 2006. The 

groupings were treated as seasonal probabilities that corresponded with quarters of the year: Spring, 

(April, May, and June); Summer, (July, August, and September); Fall, (October, November, and 

December); and Winter, (January, February, and March). These 3-month probabilities can be used to

estimate the average contact with environmental resources during a spill, treated as one spill occurring 

each day for 90 days, within the quarter. The seasonal quarterly groupings take account of the differing 

meteorological and oceanographic conditions (wind and current patterns) during the year (Figures C-2 

through C-6). As well, annualized conditional probabilities provide a useful single picture of average 

probabilities across the entire year from each launch point (Figures C-7 through C-11). 

As one might expect, environmental resources closest to the spill sites typically have the greatest risk 

of contact (Tables C-1 through C-10). As the model run duration increases, more of the resources could 

have meaningful probabilities of contact (≥0.5%). It should be reiterated that these are conditional 

probabilities; the condition being that a spill is assumed to have occurred. The longer transit times up to 

60 days allowed by the model enable hypothetical spills to reach the environmental resources and the 

shoreline from more distant spill locations. With increased travel time, the complex patterns of wind and 

ocean currents produce eddy-like motions of the oil spills and multiple opportunities for a spill to make 

contact with shoreline segments. For some launch points and for the travel times greater than 30 days, the 

probability of contact to land decreases very slowly or remains constant because the early contacts to land 

have occurred within 30 days, and the trajectories that have not contacted land within 30 days will remain 

at sea for 60 days or more.

References Cited

Applied Science Associates, Inc. 2012. SIMAP—Integrated oil spill impact model system. Internet 

website: http://www.asascience.com/software/simap/index.shtml. Accessed February 15, 2012.

Ji, Z.-G. 2004. Use of physical sciences in support of environmental management. Environmental 

Management 34(2). Pp. 159-169.

Ji, Z.-G., W.R. Johnson, C.F. Marshall, G.B. Rainey, and E.M. Lear. 2002. Oil-spill risk analysis: Gulf 

of Mexico outer continental shelf (OCS) lease sales, Central Planning Area and Western Planning 

Area, 2003-2007, and Gulfwide OCS program, 2003-2042. U.S. Dept. of the Interior, Minerals 

Management Service, Herndon, VA. OCS Report MMS 2002-032. 61 pp.

Ji, Z.-G., W.R. Johnson, and C.F. Marshall. 2004a. Deepwater oil-spill modeling for assessing 

environmental impacts. Coastal Environment V. Southampton, MA: WIT Press. Pp. 349-358.
C-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

Ji, Z.-G., W.R. Johnson, C.F. Marshall, and E.M. Lear. 2004b. Oil-spill risk analysis: Contingency 

planning statistics for Gulf of Mexico OCS activities. U.S. Dept. of the Interior, Minerals 

Management Service, Herndon, VA. OCS Report MMS 2004-026. 62 pp.

Ji, Z.-G., W.R. Johnson, and Z. Li. 2011. Oil spill risk analysis model and its application to the 

Deepwater Horizon oil spill using historical current and wind data. In: Monitoring and modeling the 

Deepwater Horizon oil spill: A record-breaking enterprise. Geophysical Monograph Series, 

doi:10.1029/2011GM001117. Pp. 227-236. Internet website: http://www.agu.org/books/gm/v195/

2011GM001117/2011GM001117.shtml. 

Oey, L.-Y. 2005. Circulation model of the Gulf of Mexico and the Caribbean Sea: Development of the 

Princeton Regional Ocean Forecast (& Hindcast) System—PROFS and Hindcast experiment for 

1992-1999: Final report. U.S. Dept. of the Interior, Minerals Management Service, Environmental 

Division, Herndon, VA. OCS Study MMS 2005-049. 174 pp.

Oey, L.-Y. 2008. Loop Current and deep eddies. Journal of Physical Oceanography 38:1426-1449.

Rhodes, R.C., J.D. Thompson, and A.J. Wallcraft. 1989. Buoys-calibrated winds over the Gulf of 

Mexico. Journal Atmospheric and Oceanic Technology 6(4):608-623.

Samuels, W.B., N.E. Huang, and D.E. Amstutz. 1982. An oil spill trajectory analysis model with a 

variable wind deflection angle. Ocean Engineering 9:347-360.

Smith, R.A., J.R. Slack, T. Wyant, and K.J. Lanfear. 1982. The oil spill risk analysis model of the U.S. 

Geological Survey. U.S. Dept. of the Interior, Geological Survey Professional Paper 1227.

Vukovich, F.M.. 2007. Climatology of ocean features in the Gulf of Mexico using satellite remote 

sensing data. Journal of Physical Oceanography 37:689-707.
BOEM-OSRA Catastrophic Run C-7 

Figure C-1. Launch Point Locations Selected for Modeling the Trajectories of Five Hypothetical Oil Spills. (The 

blue lines show the frequency (% of time) of the watermass associated with the Loop Current 

occupied an area based on data for the period 1976-2003. Adapted from Vukovich, 2007.) 
C-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

Figure C-2. Seasonal Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 1 with 

Each Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
BOEM-OSRA Catastrophic Run C-9 

Figure C-3. Seasonal Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 2 with Each 

Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land. 
C-10 Central Planning Area Lease Sales 235, 241, and 247 EIS

Figure C-4. Seasonal Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 3 with Each 

Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
BOEM-OSRA Catastrophic Run C-11

Figure C-5. Seasonal Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 4 with Each 

Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
C-12 Central Planning Area Lease Sales 235, 241, and 247 EIS

Figure C-6. Seasonal Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 5 with Each 

Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
BOEM-OSRA Catastrophic Run C-13

Figure C-7. Annual Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 1 with Each 

Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land. 
C-14 Central Planning Area Lease Sales 235, 241, and 247 EIS

Figure C-8. Annual Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 2 with Each 

Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
BOEM-OSRA Catastrophic Run C-15

Figure C-9. Annual Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 3 with Each 

Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
C-16 Central Planning Area Lease Sales 235, 241, and 247 EIS

Figure C-10. Annual Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 4 with 

Each Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
BOEM-OSRA Catastrophic Run C-17

Figure C-11. Annual Conditional Probabilities for a Hypothetical Oil Spill Initiated at Launch Point 5 with 

Each Simulated Trajectory Tracked for Up to 60 Days or Until Contacting Land.
 C-18 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-1 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make

Contact with an Onshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cameron, TX – – – – – – – – – – – 1 – – 1 2 – – – 1

Willacy, TX – – – – – – – – – – – 1 – – – 1 – – – 1

Kenedy, TX – – – – – – 2 2 – – 1 2 – – 1 4 – – 1 2

Kleberg, TX – – – – – – 1 1 – – 1 1 – – 1 2 – – 1 1

Nueces, TX – – – – – – 1 1 – – 1 2 – – 1 3 – – 1 2

Aransas, TX – – – – – – 1 2 – – 2 2 – – 1 3 – – 1 2

Calhoun, TX – – – – – – 5 5 – – 2 3 – – 3 7 – – 2 4

Matagorda, TX – – 1 1 – 1 5 6 – 1 9 9 – – 9 14 – 1 6 7

Brazoria, TX – 1 3 3 – 1 3 4 – 1 5 5 – 1 7 9 – 1 4 5

Galveston, TX – 3 9 9 – 3 9 11 – 2 9 9 – 3 10 13 – 3 9 10

Chambers, TX – – – – – – – 1 – – – – – – – – – – – –

Jefferson, TX – 5 10 10 – 3 8 8 – 3 6 6 – 2 5 6 – 3 7 7

Cameron, LA 8 36 42 42 1 12 21 23 2 11 13 15 2 9 11 12 3 17 22 23

Vermilion, LA 10 22 23 23 2 10 13 14 3 7 8 8 3 7 8 8 5 12 13 13

Iberia, LA 1 5 6 6 – 4 7 7 – 1 1 1 – 1 1 2 1 3 4 4

St. Mary, LA – 1 1 1 – – 1 1 – – – – – – – – – – 1 1

Terrebonne, LA – 2 3 3 1 3 6 6 – 1 2 2 – – 2 2 – 2 3 3

Lafourche, LA – – – – – – 1 1 – – – – – – – – – – – –

Jefferson, LA – – – – – – – – – – – – – – – – – – – –

Plaquemines, LA – – – – – – 1 1 – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-19

Table C-1. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

St. Bernard, LA – – – – – – – – – – – – – – – – – – – –

Hancock, MS – – – – – – – – – – – – – – – – – – – –

Harrison, MS – – – – – – – – – – – – – – – – – – – –

Jackson, MS – – – – – – – – – – – – – – – – – – – –

Mobile, AL – – – – – – – – – – – – – – – – – – – –

Baldwin, AL – – – – – – – – – – – – – – – – – – – –

Escambia, FL – – – – – – – – – – – – – – – – – – – –

Santa Rosa, FL – – – – – – – – – – – – – – – – – – – –

Okaloosa, FL – – – – – – – – – – – – – – – – – – – –

Walton, FL – – – – – – – – – – – – – – – – – – – –

Bay, FL – – – – – – – – – – – – – – – – – – – –

Gulf, FL – – – – – – – – – – – – – – – – – – – –

Franklin, FL – – – – – – – – – – – – – – – – – – – –

Wakulla, FL – – – – – – – – – – – – – – – – – – – –

Jefferson, FL – – – – – – – – – – – – – – – – – – – –

Taylor, FL – – – – – – – – – – – – – – – – – – – –

Dixie, FL – – – – – – – – – – – – – – – – – – – –

Levy, FL – – – – – – – – – – – – – – – – – – – –

Citrus, FL – – – – – – – – – – – – – – – – – – – –

Hernando, FL – – – – – – – – – – – – – – – – – – – –

Pasco, FL – – – – – – – – – – – – – – – – – – – –

Pinellas, FL – – – – – – – – – – – – – – – – – – – –

Hillsborough, FL – – – – – – – – – – – – – – – – – – – –

Manatee, FL – – – – – – – – – – – – – – – – – – – –
 C-20 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-1. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sarasota, FL – – – – – – – – – – – – – – – – – – – –

Charlotte, FL – – – – – – – – – – – – – – – – – – – –

Lee, FL – – – – – – – – – – – – – – – – – – – –

Collier, FL – – – – – – – – – – – – – – – – – – – –

Monroe, FL – – – – – – – – – – – – – – – – – – – –

Dade, FL – – – – – – – – – – – – – – – – – – – –

Broward, FL – – – – – – – – – – – – – – – – – – – –

Palm Beach, FL – – – – – – – – – – – – – – – – – – – –

Martin, FL – – – – – – – – – – – – – – – – – – – –

St. Lucie, FL – – – – – – – – – – – – – – – – – – – –

Indian River, FL – – – – – – – – – – – – – – – – – – – –

Brevard, FL – – – – – – – – – – – – – – – – – – – –

Volusia, FL – – – – – – – – – – – – – – – – – – – –

Flagler, FL – – – – – – – – – – – – – – – – – – – –

St. Johns, FL – – – – – – – – – – – – – – – – – – – –

Duval, FL – – – – – – – – – – – – – – – – – – – –

Nassau, FL – – – – – – – – – – – – – – – – – – – –

TX – 11 23 23 – 7 36 41 – 7 36 41 – 6 39 64 – 8 33 43

LA 19 66 76 76 5 30 49 52 6 20 25 27 5 17 22 24 9 33 43 45

MS – – – – – – – – – – – – – – – – – – – –

AL – – – – – – – – – – – – – – – – – – – –

FL – – – – – – – – – – – – – – – – – – – –

Tamaulipas, 

Mexico – – – – – – 1 1 – – – 1 – – – – – – – 1
BOEM-OSRA Catastrophic Run

C-21

Table C-1. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Veracruz-Llave, 

Mexico – – – – – – – – – – – – – – – – – – – –

Tabasco, Mexico – – – – – – – – – – – – – – – – – – – –

Campeche, Mexico – – – – – – – – – – – – – – – – – – – –

Yucatan, Mexico – – – – – – – – – – – – – – – – – – – –

Quintana Roo, 

Mexico – – – – – – – – – – – – – – – – – – – –

Belize (country) – – – – – – – – – – – – – – – – – – – –

Cuba – – – – – – – – – – – – – – – – – – – –

Passerines – 4 5 5 – 1 15 17 – 2 11 16 – 1 11 28 – 2 11 17

Raptors – 10 18 18 – 4 27 30 – 6 23 28 – 5 23 43 – 6 23 30

Shorebirds 6 28 39 39 2 14 45 50 2 13 35 40 1 10 34 56 3 16 38 46

Wading Birds – – – – – – – – – – – – – – – – – – – –

Waterfowl 19 63 75 76 5 29 62 66 6 20 39 45 5 17 38 58 9 32 53 61

Diving Birds 19 70 88 88 5 33 75 81 6 24 49 56 5 20 48 71 9 37 65 74

Gulls/Terns 19 71 90 90 5 34 77 83 6 25 53 59 5 21 51 75 9 38 68 77

Piping Plover 6 14 16 16 3 15 36 39 5 19 32 35 5 15 29 37 5 16 29 32

Sea Turtle Nesting 

Habitat I – 11 23 23 – 7 24 28 – – – – – 1 9 15 – 5 14 16

Sea Turtle Nesting 

Habitat II – – – – – – – – – – – – – – – – – – – –

Sea Turtle Sporadic 

Nesting Habitat I 19 66 76 76 5 30 49 51 – – – – – 1 3 4 6 24 32 33

Sea Turtle Sporadic 

Nesting Habitat II – – – – – – – – – – – – – – – – – – – –

West Indian 

Manatee Habitat – – – – – – – – – – – – – – – – – – – –
 C-22 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-1. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

West Indian 

Manatee Sporadic 

Habitat – – – – – – – – – – – – – – – – – – – –

West Indian 

Manatee Rare 

Habitat 19 77 99 99 5 37 85 92 2 9 17 17 – 2 12 19 6 31 53 57

Alabama Beach 

Mouse – – – – – – – – – – – – – – – – – – – –

Perdido Key Beach 

Mouse – – – – – – – – – – – – – – – – – – – –

Santa Rosa Beach 

Mouse – – – – – – – – – – – – – – – – – – – –

Choctawhatchee 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

St. Andrews Beach 

Mouse – – – – – – – – – – – – – – – – – – – –

Southeastern Beach 

Mouse – – – – – – – – – – – – – – – – – – – –

Anastasia Island 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Smalltooth Sawfish 

Critical Habitat – – – – – – – – – – – – – – – – – – – –

Short Nose 

Sturgeon – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon 

Critical Habitat – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon – – – – – – – – – – – – – – – – – – – –

TX Coastal Bend 

Beach Area – – – – – – 5 7 – – 5 9 – – 4 16 – – 4 8

TX Matagorda 

Beach Area – – 1 1 – 1 9 10 – 1 11 12 – – 12 20 – 1 9 11
BOEM-OSRA Catastrophic Run

C-23

Table C-1. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

TX Galveston 

Beach Area – 5 12 12 – 4 13 16 – 3 14 14 – 4 17 22 – 4 14 16

TX Sea Rim State 

Park – 5 10 10 – 3 8 8 – 3 6 6 – 2 5 6 – 3 7 7

LA Beach Areas 8 36 42 42 1 12 22 24 2 11 14 15 2 9 11 13 3 17 22 23

AL/MS Gulf 

Islands – – – – – – – – – – – – – – – – – – – –

AL Gulf Shores – – – – – – – – – – – – – – – – – – – –

FL Panhandle 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Big Bend Beach 

Area – – – – – – – – – – – – – – – – – – – –

FL Southwest 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Ten Thousand 

Islands Area – – – – – – – – – – – – – – – – – – – –

FL Southeast Beach 

Area – – – – – – – – – – – – – – – – – – – –

FL Central East 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Northeast Beach 

Area – – – – – – – – – – – – – – – – – – – –

FL Gulf Coast 

Jaguarondi and 

Ocelot – – – – – – 5 7 – – 5 9 – – 4 16 – – 4 8

Louisiana Black 

Bear 1 6 8 8 – 5 7 7 – 1 2 2 – 2 2 2 1 3 5 5

Northern Aplomado 

Falcon – – – – – – – 1 – – 1 2 – – 1 3 – – – 1

Whooping Crane 1 – – – – – – 6 6 – – 4 5 – – 4 10 – – 4 5

Whooping Crane 2 10 22 23 23 2 10 13 14 3 7 8 8 3 7 8 8 5 12 13 13
 C-24 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-1. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Wood Stork – – – – – – – – – – – – – – – – – – – –

Alabama Redbellied Turtle – – – – – – – – – – – – – – – – – – – –

Gopher Tortoise 

and Louisiana 

Quillwort – – – – – – – – – – – – – – – – – – – –

Eastern Indigo 

Snake – – – – – – – – – – – – – – – – – – – –

Mississippi Gopher 

Frog – – – – – – – – – – – – – – – – – – – –

Flatwoods 

Salamander – – – – – – – – – – – – – – – – – – – –

Telephus Spurge – – – – – – – – – – – – – – – – – – – –

Mississippi 

Sandhill Crane – – – – – – – – – – – – – – – – – – – –

Everglades Snail 

Kite – – – – – – – – – – – – – – – – – – – –

Cape Sable Seaside 

Sparrow – – – – – – – – – – – – – – – – – – – –

Roseate Tern – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
BOEM-OSRA Catastrophic Run

C-25

Table C-2 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make

Contact with an Onshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cameron, TX – – – – – – – – – – – – – – – – – – – –

Willacy, TX – – – – – – – – – – – – – – – – – – – –

Kenedy, TX – – – – – – – – – – – – – – – – – – – –

Kleberg, TX – – – – – – – – – – – – – – – – – – – –

Nueces, TX – – – – – – – – – – – – – – – – – – – –

Aransas, TX – – – – – – – – – – – – – – – – – – – –

Calhoun, TX – – – – – – – – – – – – – – – – – – – –

Matagorda, TX – – – – – – – – – – – – – – – 1 – – – –

Brazoria, TX – – – – – – – – – – – – – – – – – – – –

Galveston, TX – – – – – – – – – – – – – – – – – – – –

Chambers, TX – – – – – – – – – – – – – – – – – – – –

Jefferson, TX – – – – – – – – – – – – – – – – – – – –

Cameron, LA – – – – – – – – – – – – – – – – – – – –

Vermilion, LA – – – – – – – – – – – – – – – 1 – – – –

Iberia, LA – – – – – – – – – – – – – – – – – – – –

St. Mary, LA – – – – – – – – – – – – – – – – – – – –

Terrebonne, LA – – – – – – – 1 – – – – – – 2 2 – – 1 1

Lafourche, LA – – – – – – – – – – 1 1 – – – 1 – – – –

Jefferson, LA – – – – – – – – – – – – – – 1 1 – – – –

Plaquemines, LA – 2 3 3 2 9 17 19 2 17 24 24 1 12 18 20 1 10 15 17
 C-26 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-2. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

St. Bernard, LA – 5 6 6 1 8 13 14 1 8 10 10 1 5 8 8 1 7 9 10

Hancock, MS – 2 3 3 – 2 2 2 1 2 3 3 – 1 2 3 – 2 3 3

Harrison, MS 2 5 5 5 1 4 5 5 1 2 3 3 2 3 4 4 1 3 4 4

Jackson, MS 7 13 14 14 3 6 8 8 6 11 12 13 6 10 12 13 6 10 11 12

Mobile, AL 13 18 19 19 4 9 10 10 8 12 12 13 9 12 13 13 9 13 14 14

Baldwin, AL 8 15 18 18 2 8 9 9 1 2 3 3 3 6 7 7 3 8 9 9

Escambia, FL 1 6 9 10 1 4 6 6 – 1 1 1 – 2 2 3 – 3 5 5

Santa Rosa, FL – – – – – – – – – – – – – – – – – – – –

Okaloosa, FL – 1 2 2 – 1 2 2 – – – – – – – – – – 1 1

Walton, FL – – 1 1 – 1 1 1 – – – 1 – – – – – – 1 1

Bay, FL – 2 3 3 – 1 2 3 – – – – – – – 1 – 1 1 2

Gulf, FL – 1 3 4 – – 2 2 – – – – – – – – – – 1 1

Franklin, FL – – 1 2 – – 1 1 – – – – – – – – – – – 1

Wakulla, FL – – – – – – – – – – – – – – – – – – – –

Jefferson, FL – – – – – – – – – – – – – – – – – – – –

Taylor, FL – – – – – – – – – – – – – – – – – – – –

Dixie, FL – – – 1 – – – – – – – – – – – – – – – –

Levy, FL – – – 1 – – – – – – – – – – – – – – – –

Citrus, FL – – – – – – – – – – – – – – – – – – – –

Hernando, FL – – – – – – – – – – – – – – – – – – – –

Pasco, FL – – – – – – – – – – – – – – – – – – – –

Pinellas, FL – – – – – – – – – – – – – – – – – – – –

Hillsborough, FL – – – – – – – – – – – – – – – – – – – –

Manatee, FL – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-27

Table C-2. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sarasota, FL – – – – – – – – – – – – – – – – – – – –

Charlotte, FL – – – – – – – – – – – – – – – – – – – –

Lee, FL – – – – – – – – – – – – – – – – – – – –

Collier, FL – – – – – – – – – – – – – – – – – – – –

Monroe, FL – – – – – – – – – – – – – – – – – – – –

Dade, FL – – – – – – – – – – – – – – – – – – – –

Broward, FL – – – – – – – – – – – – – – – – – – – –

Palm Beach, FL – – – – – – – – – – – – – – – – – – – –

Martin, FL – – – – – – – – – – – – – – – – – – – –

St. Lucie, FL – – – – – – – – – – – – – – – – – – – –

Indian River, FL – – – – – – – – – – – – – – – – – – – –

Brevard, FL – – – – – – – – – – – – – – – – – – – –

Volusia, FL – – – – – – – – – – – – – – – – – – – –

Flagler, FL – – – – – – – – – – – – – – – – – – – –

St. Johns, FL – – – – – – – – – – – – – – – – – – – –

Duval, FL – – – – – – – – – – – – – – – – – – – –

Nassau, FL – – – – – – – – – – – – – – – – – – – –

TX – – – – – – – 1 – – 1 2 – – – 2 – – – 1

LA – 6 8 9 3 17 30 35 3 25 36 36 2 18 29 33 2 17 26 28

MS 9 20 22 22 5 12 15 15 8 15 18 19 8 15 18 20 7 15 18 19

AL 21 33 37 37 6 17 20 20 9 14 15 15 12 18 20 20 12 20 23 23

FL 1 11 19 26 1 7 14 16 – 1 3 3 – 2 4 5 1 5 10 13

Tamaulipas, 

Mexico – – – – – – – – – – – – – – – – – – – –
 C-28 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-2. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Veracruz-Llave, 

Mexico – – – – – – – – – – – – – – – – – – – –

Tabasco, Mexico – – – – – – – – – – – – – – – – – – – –

Campeche, 

Mexico – – – – – – – – – – – – – – – – – – – –

Yucatan, Mexico – – – – – – – – – – – – – – – – – – – –

Quintana Roo, 

Mexico – – – – – – – – – – – – – – – – – – – –

Belize (country) – – – – – – – – – – – – – – – – – – – –

Cuba – – – – – – – – – – – – – – – – – – – –

Passerines 28 53 61 62 12 33 42 45 17 31 37 39 19 33 39 44 19 38 45 48

Raptors 22 37 42 46 7 17 24 26 13 19 22 23 15 22 24 27 14 24 28 31

Shorebirds 23 44 53 58 8 24 34 38 13 23 28 30 15 26 33 39 15 29 37 41

Wading Birds 27 48 54 55 11 28 36 37 17 30 34 36 19 31 36 40 18 34 40 42

Waterfowl 19 37 43 45 9 33 50 56 13 41 54 56 13 35 48 56 14 36 49 53

Diving Birds 31 60 67 68 14 46 65 72 20 54 69 72 22 50 66 75 22 52 67 72

Gulls/Terns 31 61 72 76 13 36 52 58 19 42 55 58 22 43 57 67 21 46 59 65

Piping Plover 11 18 20 20 7 23 32 35 17 31 39 42 19 32 41 46 14 26 33 36

Sea Turtle 

Nesting Habitat I – – – 1 – – – – – – – – – – – 1 – – – –

Sea Turtle 

Nesting Habitat 

II 32 64 77 83 12 35 48 51 11 19 20 21 1 3 4 8 14 30 37 41

Sea Turtle 

Sporadic Nesting 

Habitat I – – 1 1 – – – 1 – – – – – – 1 2 – – 1 1

Sea Turtle 

Sporadic Nesting 

Habitat II – 6 9 10 3 17 29 33 2 18 24 24 – 1 4 4 2 11 17 18
BOEM-OSRA Catastrophic Run

C-29

Table C-2. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

West Indian 

Manatee Habitat 1 11 19 26 1 7 14 16 – 1 3 3 – 2 4 5 1 5 10 13

West Indian 

Manatee 

Sporadic Habitat 31 58 65 66 13 38 50 52 5 13 14 14 1 3 5 8 12 28 34 35

West Indian 

Manatee Rare 

Habitat – 2 2 3 2 8 15 19 1 6 6 6 – 1 3 5 1 4 7 8

Alabama Beach 

Mouse 8 15 18 18 2 8 9 9 1 2 3 3 3 6 7 7 3 8 9 9

Perdido Key 

Beach Mouse 9 21 27 28 3 12 15 16 1 3 4 4 3 7 9 10 4 11 14 15

Santa Rosa 

Beach Mouse – 3 5 6 – 3 4 5 – 1 1 1 – 1 2 2 – 2 3 3

Choctawhatchee 

Beach Mouse – 3 6 7 – 2 5 6 – – 1 1 – 1 1 1 – 2 3 4

St. Andrews 

Beach Mouse – 3 5 7 – 1 4 5 – – – – – – – 1 – 1 2 3

Southeastern 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Anastasia Island 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Smalltooth 

Sawfish Critical 

Habitat – – – 1 – – – – – – – – – – – – – – – –

Short Nose 

Sturgeon – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon 

Critical Habitat 32 69 83 89 13 44 62 65 18 40 47 48 21 40 49 54 21 48 60 64

Gulf Sturgeon 32 70 86 92 15 52 78 83 20 55 68 70 22 51 65 71 22 57 74 79

TX Coastal Bend 

Beach Area – – – – – – – 1 – – – 1 – – – 1 – – – 1
 C-30 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-2. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

TX Matagorda 

Beach Area – – – – – – – – – – – 1 – – – 1 – – – –

TX Galveston 

Beach Area – – – – – – – – – – – – – – – 1 – – – –

TX Sea Rim 

State Park – – – – – – – – – – – – – – – – – – – –

LA Beach Areas – – – – – – – 1 – – 1 1 – – 1 2 – – 1 1

AL/MS Gulf 

Islands 23 38 41 41 9 21 25 26 16 27 30 32 17 27 30 33 16 28 32 33

AL Gulf Shores 8 15 18 18 2 8 9 9 1 2 3 3 3 6 7 7 3 8 9 9

FL Panhandle 

Beach Area 1 11 18 23 1 7 14 15 – 1 3 3 – 2 4 5 1 5 10 11

FL Big Bend 

Beach Area – – 1 2 – – – – – – – – – – – – – – – 1

FL Southwest 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Ten Thousand 

Islands Area – – – – – – – – – – – – – – – – – – – –

FL Southeast 

Beach Area – – – 1 – – – 1 – – – – – – – – – – – 1

FL Central East 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Northeast 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Gulf Coast 

Jaguarondi and 

Ocelot – – – – – – – 1 – – – 1 – – – 1 – – – 1

Louisiana Black 

Bear – – – – – – – – – – – – – – – – – – – –

Northern 

Aplomado 

Falcon – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-31

Table C-2. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Whooping 

Crane 1 – – – – – – – 1 – – – – – – – – – – – –

Whooping 

Crane 2 – – – – – – – – – – – – – – – 1 – – – –

Wood Stork 22 44 56 63 7 24 34 36 9 15 18 18 12 20 23 25 13 26 33 36

Alabama Redbellied Turtle 30 51 56 57 11 27 32 33 16 27 30 31 20 31 35 37 19 34 38 39

Gopher Tortoise 

and Louisiana 

Quillwort 9 20 22 22 5 12 15 15 8 15 18 19 8 15 18 20 7 15 18 19

Eastern Indigo 

Snake 1 11 19 26 1 7 14 16 – 1 3 3 – 2 4 5 1 5 10 13

Mississippi 

Gopher Frog 9 18 19 19 4 10 13 13 7 13 15 16 8 13 16 17 7 14 16 16

Flatwoods 

Salamander – – 1 2 – – 1 1 – – – – – – – – – – – 1

Telephus Spurge – 3 6 9 – 1 5 5 – – – – – – – 1 – 1 3 4

Mississippi 

Sandhill Crane 9 18 19 19 4 10 13 13 7 13 15 16 8 13 16 17 7 14 16 16

Everglades Snail 

Kite – – – 1 – – – 1 – – – – – – – – – – – 1

Cape Sable 

Seaside Sparrow – – – 1 – – – – – – – – – – – – – – – –

Roseate Tern – – – 1 – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
 C-32 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-3 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make

Contact with an Onshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cameron, TX – – – – – – – 2 – – – 1 – – – 1 – – – 1

Willacy, TX – – – – – – – 1 – – – 1 – – – 2 – – – 1

Kenedy, TX – – – – – – 1 5 – – – 2 – – – 3 – – – 3

Kleberg, TX – – – – – – 1 3 – – 1 2 – – – 2 – – – 2

Nueces, TX – – – – – – – 2 – – 1 2 – – – 3 – – – 1

Aransas, TX – – – – – – – 2 – – 1 2 – – – 3 – – – 2

Calhoun, TX – – – – – – – 3 – – 1 2 – – 1 4 – – 1 2

Matagorda, TX – – 3 5 – – 1 4 – – 2 5 – – 3 10 – – 2 6

Brazoria, TX – – 3 3 – – 2 5 – – 1 2 – – 3 8 – – 2 5

Galveston, TX – – 3 5 – – 2 3 – – 1 2 – – 2 5 – – 2 4

Chambers, TX – – – – – – – – – – – – – – – – – – – –

Jefferson, TX – – 4 5 – – 1 1 – – – – – – 1 2 – – 1 2

Cameron, LA – – 9 11 – – 1 3 – – – 2 – – 1 3 – – 3 5

Vermilion, LA – 1 5 6 – – 1 1 – – – – – – 1 2 – – 2 2

Iberia, LA – 1 3 3 – – – – – – – – – – – 1 – – 1 1

St. Mary, LA – – 1 1 – – – – – – – – – – – – – – – –

Terrebonne, LA – 5 12 13 – – 1 2 – – 1 1 – 1 2 2 – 2 4 5

Lafourche, LA – 2 5 6 – – 1 2 – – – – – – 1 2 – 1 2 2

Jefferson, LA – – 1 1 – – – 1 – – – – – – – – – – 1 1

Plaquemines, LA – 3 10 10 – – 2 3 – – – – – – 2 2 – 1 3 4
BOEM-OSRA Catastrophic Run

C-33

Table C-3. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

St. Bernard, LA – – 1 1 – – – – – – – – – – – – – – – –

Hancock, MS – – – – – – – – – – – – – – – – – – – –

Harrison, MS – – – – – – – – – – – – – – – – – – – –

Jackson, MS – – – – – – – – – – – – – – – – – – – –

Mobile, AL – – – – – – – – – – – – – – – – – – – –

Baldwin, AL – – 1 1 – – – – – – – – – – – – – – – –

Escambia, FL – – 1 1 – – – – – – – – – – – – – – – –

Santa Rosa, FL – – – – – – – – – – – – – – – – – – – –

Okaloosa, FL – – – 1 – – – – – – – – – – – – – – – –

Walton, FL – – – – – – – – – – – – – – – – – – – –

Bay, FL – – – 1 – – – – – – – – – – – – – – – –

Gulf, FL – – – – – – – – – – – – – – – – – – – –

Franklin, FL – – – – – – – – – – – – – – – – – – – –

Wakulla, FL – – – – – – – – – – – – – – – – – – – –

Jefferson, FL – – – – – – – – – – – – – – – – – – – –

Taylor, FL – – – – – – – – – – – – – – – – – – – –

Dixie, FL – – – – – – – – – – – – – – – – – – – –

Levy, FL – – – – – – – – – – – – – – – – – – – –

Citrus, FL – – – – – – – – – – – – – – – – – – – –

Hernando, FL – – – – – – – – – – – – – – – – – – – –

Pasco, FL – – – – – – – – – – – – – – – – – – – –

Pinellas, FL – – – – – – – – – – – – – – – – – – – –

Hillsborough, FL – – – – – – – – – – – – – – – – – – – –

Manatee, FL – – – – – – – – – – – – – – – – – – – –
 C-34 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-3. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sarasota, FL – – – – – – – – – – – – – – – – – – – –

Charlotte, FL – – – – – – – – – – – – – – – – – – – –

Lee, FL – – – – – – – – – – – – – – – – – – – –

Collier, FL – – – – – – – – – – – – – – – – – – – –

Monroe, FL – – – – – – – – – – – – – – – – – – – –

Dade, FL – – – – – – – 1 – – – – – – – – – – – –

Broward, FL – – – – – – – – – – – – – – – – – – – –

Palm Beach, FL – – – – – – – – – – – – – – – – – – – –

Martin, FL – – – – – – – – – – – – – – – – – – – –

St. Lucie, FL – – – – – – – – – – – – – – – – – – – –

Indian River, FL – – – – – – – – – – – – – – – – – – – –

Brevard, FL – – – – – – – – – – – – – – – – – – – –

Volusia, FL – – – – – – – – – – – – – – – – – – – –

Flagler, FL – – – – – – – – – – – – – – – – – – – –

St. Johns, FL – – – – – – – – – – – – – – – – – – – –

Duval, FL – – – – – – – – – – – – – – – – – – – –

Nassau, FL – – – – – – – – – – – – – – – – – – – –

TX – – 13 19 – – 7 30 – – 7 21 – – 11 44 – – 10 28

LA – 12 46 52 – 2 6 12 – 1 2 4 – 2 8 12 – 4 16 20

MS – – 1 1 – – – 1 – – – – – – – – – – – –

AL – – 1 1 – – – – – – – – – – – – – – – –

FL – – 2 5 – – – 2 – – – – – – – 1 – – 1 2

Tamaulipas, 

Mexico – – – – – – – 4 – – – 3 – – – 1 – – – 2
BOEM-OSRA Catastrophic Run

C-35

Table C-3. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Veracruz-Llave, 

Mexico – – – – – – – 2 – – – 2 – – – – – – – 1

Tabasco, Mexico – – – – – – – – – – – – – – – – – – – –

Campeche, Mexico – – – – – – – – – – – – – – – – – – – –

Yucatan, Mexico – – – – – – – – – – – – – – – – – – – –

Quintana Roo, 

Mexico – – – – – – – – – – – – – – – – – – – –

Belize (country) – – – – – – – – – – – – – – – – – – – –

Cuba – – – – – – – – – – – – – – – – – – – –

Passerines – – 5 7 – – 3 21 – – 5 14 – – 3 23 – – 4 16

Raptors – – 10 15 – – 6 25 – – 6 16 – – 5 29 – – 7 21

Shorebirds – 8 36 44 – 1 10 34 – 1 8 19 – 1 11 40 – 3 16 35

Wading Birds – – 1 2 – – – 1 – – – – – – – – – – – 1

Waterfowl – 12 49 57 – 2 11 35 – 1 8 20 – 2 12 38 – 4 20 38

Diving Birds – 12 56 66 – 2 12 39 – 1 8 21 – 2 15 47 – 4 23 43

Gulls/Terns – 13 58 69 – 2 13 41 – 1 8 22 – 2 16 50 – 4 24 46

Piping Plover – 2 4 6 – 1 6 16 – 1 5 10 – 1 8 18 – 1 6 12

Sea Turtle Nesting 

Habitat I – – 13 19 – – 3 11 – – – – – – 7 24 – – 6 13

Sea Turtle Nesting 

Habitat II – – 3 7 – – 1 3 – – – – – – – 1 – – 1 3

Sea Turtle Sporadic 

Nesting Habitat I – 11 43 48 – 1 6 10 – – – – – – 3 7 – 3 13 16

Sea Turtle Sporadic 

Nesting Habitat II – 1 3 4 – – 1 2 – – – – – – – – – – 1 2

West Indian 

Manatee Habitat – – 2 5 – – – 2 – – – – – – – 1 – – 1 2
 C-36 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-3. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

West Indian 

Manatee Sporadic 

Habitat – – 2 3 – – – 1 – – – – – – – – – – 1 1

West Indian 

Manatee Rare 

Habitat – 12 59 70 – 2 13 36 – – 2 2 – – 11 30 – 4 21 34

Alabama Beach 

Mouse – – 1 1 – – – – – – – – – – – – – – – –

Perdido Key Beach 

Mouse – – 2 2 – – – – – – – – – – – – – – – 1

Santa Rosa Beach 

Mouse – – 1 1 – – – – – – – – – – – – – – – –

Choctawhatchee 

Beach Mouse – – 1 2 – – – – – – – – – – – – – – – 1

St. Andrews Beach 

Mouse – – – 1 – – – – – – – – – – – – – – – –

Southeastern Beach 

Mouse – – – – – – – 1 – – – – – – – – – – – –

Anastasia Island 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Smalltooth Sawfish 

Critical Habitat – – – – – – – – – – – – – – – – – – – –

Short Nose 

Sturgeon – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon 

Critical Habitat – – 4 7 – – 1 2 – – – – – – – – – – 1 2

Gulf Sturgeon – 1 6 10 – – 1 3 – – – – – – 1 1 – – 2 3

TX Coastal Bend 

Beach Area – – – – – – 2 14 – – 3 10 – – 1 14 – – 2 10

TX Matagorda 

Beach Area – – 3 5 – – 1 7 – – 3 7 – – 3 15 – – 3 8
BOEM-OSRA Catastrophic Run

C-37

Table C-3. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

TX Galveston 

Beach Area – – 6 9 – – 3 8 – – 1 5 – – 5 13 – – 4 8

TX Sea Rim State 

Park – – 4 5 – – 1 1 – – – – – – 1 2 – – 1 2

LA Beach Areas – 3 15 18 – 1 3 5 – – 1 3 – – 2 5 – 1 5 8

AL/MS Gulf 

Islands – – 1 1 – – – 1 – – – – – – – – – – – –

AL Gulf Shores – – 1 1 – – – – – – – – – – – – – – – –

FL Panhandle 

Beach Area – – 2 4 – – – – – – – – – – – – – – 1 1

FL Big Bend Beach 

Area – – – – – – – – – – – – – – – – – – – –

FL Southwest 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Ten Thousand 

Islands Area – – – – – – – – – – – – – – – – – – – –

FL Southeast Beach 

Area – – – – – – – 1 – – – – – – – 1 – – – 1

FL Central East 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Northeast Beach 

Area – – – – – – – – – – – – – – – – – – – –

FL Gulf Coast 

Jaguarondi and 

Ocelot – – – – – – 2 14 – – 3 10 – – 1 14 – – 2 10

Louisiana Black 

Bear – 1 4 4 – – – – – – – – – – – 1 – – 1 1

Northern Aplomado 

Falcon – – – – – – – 2 – – – 2 – – – 3 – – – 2

Whooping Crane 1 – – – – – – 1 5 – – 2 4 – – 1 7 – – 1 4

Whooping Crane 2 – 1 5 6 – – 1 1 – – – – – – 1 2 – – 2 2
 C-38 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-3. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Onshore

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Wood Stork – – 3 7 – – 1 2 – – – – – – – 1 – – 1 3

Alabama Redbellied Turtle – – 1 2 – – – 1 – – – – – – – – – – – 1

Gopher Tortoise 

and Louisiana 

Quillwort – – 1 1 – – – 1 – – – – – – – – – – – –

Eastern Indigo 

Snake – – 2 5 – – – 2 – – – – – – – 1 – – 1 2

Mississippi Gopher 

Frog – – – – – – – – – – – – – – – – – – – –

Flatwoods 

Salamander – – – – – – – – – – – – – – – – – – – –

Telephus Spurge – – – 2 – – – – – – – – – – – – – – – –

Mississippi 

Sandhill Crane – – – – – – – – – – – – – – – – – – – –

Everglades Snail 

Kite – – – – – – – 1 – – – – – – – 1 – – – 1

Cape Sable Seaside 

Sparrow – – – – – – – 1 – – – – – – – – – – – –

Roseate Tern – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
BOEM-OSRA Catastrophic Run

C-39

Table C-4 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make

Contact with an Onshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cameron, TX – – – – – – – – – 2 2 2 1 2 2 2 – 1 1 1

Willacy, TX 1 1 1 1 – 1 1 1 2 5 6 6 2 3 3 3 1 2 3 3

Kenedy, TX 5 7 7 7 5 9 9 9 10 22 23 24 10 22 23 23 8 15 16 16

Kleberg, TX 8 11 11 11 8 13 13 13 7 12 12 12 9 14 14 14 8 12 13 13

Nueces, TX 23 27 27 27 12 19 19 19 13 18 19 19 12 19 20 20 15 21 21 21

Aransas, TX 33 36 36 36 18 26 26 26 10 13 14 14 10 16 17 17 18 23 23 23

Calhoun, TX 11 14 14 14 15 22 23 23 7 11 12 13 5 10 11 11 10 14 15 15

Matagorda, TX 1 2 2 2 1 4 5 5 – 1 2 2 – 2 2 2 1 2 3 3

Brazoria, TX – – – – – – – – – – 1 1 – – 1 1 – – – –

Galveston, TX – – – – – – – – – – – – – – – – – – – –

Chambers, TX – – – – – – – – – – – – – – – – – – – –

Jefferson, TX – – – – – – – – – – – – – – – – – – – –

Cameron, LA – – – – – – – – – – – – – – – – – – – –

Vermilion, LA – – – – – – – – – – – – – – – – – – – –

Iberia, LA – – – – – – – – – – – – – – – – – – – –

St. Mary, LA – – – – – – – – – – – – – – – – – – – –

Terrebonne, LA – – – – – – – – – – – – – – – – – – – –

Lafourche, LA – – – – – – – – – – – – – – – – – – – –

Jefferson, LA – – – – – – – – – – – – – – – – – – – –

Plaquemines, LA – – – – – – – – – – – – – – – – – – – –
 C-40 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-4. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

St. Bernard, LA – – – – – – – – – – – – – – – – – – – –

Hancock, MS – – – – – – – – – – – – – – – – – – – –

Harrison, MS – – – – – – – – – – – – – – – – – – – –

Jackson, MS – – – – – – – – – – – – – – – – – – – –

Mobile, AL – – – – – – – – – – – – – – – – – – – –

Baldwin, AL – – – – – – – – – – – – – – – – – – – –

Escambia, FL – – – – – – – – – – – – – – – – – – – –

Santa Rosa, FL – – – – – – – – – – – – – – – – – – – –

Okaloosa, FL – – – – – – – – – – – – – – – – – – – –

Walton, FL – – – – – – – – – – – – – – – – – – – –

Bay, FL – – – – – – – – – – – – – – – – – – – –

Gulf, FL – – – – – – – – – – – – – – – – – – – –

Franklin, FL – – – – – – – – – – – – – – – – – – – –

Wakulla, FL – – – – – – – – – – – – – – – – – – – –

Jefferson, FL – – – – – – – – – – – – – – – – – – – –

Taylor, FL – – – – – – – – – – – – – – – – – – – –

Dixie, FL – – – – – – – – – – – – – – – – – – – –

Levy, FL – – – – – – – – – – – – – – – – – – – –

Citrus, FL – – – – – – – – – – – – – – – – – – – –

Hernando, FL – – – – – – – – – – – – – – – – – – – –

Pasco, FL – – – – – – – – – – – – – – – – – – – –

Pinellas, FL – – – – – – – – – – – – – – – – – – – –

Hillsborough, FL – – – – – – – – – – – – – – – – – – – –

Manatee, FL – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-41

Table C-4. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sarasota, FL – – – – – – – – – – – – – – – – – – – –

Charlotte, FL – – – – – – – – – – – – – – – – – – – –

Lee, FL – – – – – – – – – – – – – – – – – – – –

Collier, FL – – – – – – – – – – – – – – – – – – – –

Monroe, FL – – – – – – – – – – – – – – – – – – – –

Dade, FL – – – – – – – – – – – – – – – – – – – –

Broward, FL – – – – – – – – – – – – – – – – – – – –

Palm Beach, FL – – – – – – – – – – – – – – – – – – – –

Martin, FL – – – – – – – – – – – – – – – – – – – –

St. Lucie, FL – – – – – – – – – – – – – – – – – – – –

Indian River, FL – – – – – – – – – – – – – – – – – – – –

Brevard, FL – – – – – – – – – – – – – – – – – – – –

Volusia, FL – – – – – – – – – – – – – – – – – – – –

Flagler, FL – – – – – – – – – – – – – – – – – – – –

St. Johns, FL – – – – – – – – – – – – – – – – – – – –

Duval, FL – – – – – – – – – – – – – – – – – – – –

Nassau, FL – – – – – – – – – – – – – – – – – – – –

TX 82 97 97 98 58 94 96 96 49 84 92 93 48 87 93 93 60 91 95 95

LA – – – – – – – – – – – – – – – – – – – –

MS – – – – – – – – – – – – – – – – – – – –

AL – – – – – – – – – – – – – – – – – – – –

FL – – – – – – – – – – – – – – – – – – – –

Tamaulipas, 

Mexico – – – – – – – – – – 1 1 – – 1 1 – – – –
 C-42 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-4. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Veracruz-Llave, 

Mexico – – – – – – – – – – – – – – – – – – – –

Tabasco, Mexico – – – – – – – – – – – – – – – – – – – –

Campeche, 

Mexico – – – – – – – – – – – – – – – – – – – –

Yucatan, Mexico – – – – – – – – – – – – – – – – – – – –

Quintana Roo, 

Mexico – – – – – – – – – – – – – – – – – – – –

Belize (country) – – – – – – – – – – – – – – – – – – – –

Cuba – – – – – – – – – – – – – – – – – – – –

Passerines 82 96 97 97 58 91 93 93 49 83 90 91 48 87 91 92 59 89 93 93

Raptors 82 96 97 97 58 92 93 93 49 84 91 91 48 87 92 92 59 90 93 94

Shorebirds 82 96 97 97 58 92 94 94 49 84 91 92 48 87 92 93 59 90 93 94

Wading Birds – – – – – – – – – – – – – – – – – – – –

Waterfowl 82 96 97 97 58 92 93 93 49 84 91 91 48 87 92 92 59 90 93 94

Diving Birds 82 96 97 97 58 92 94 94 49 84 91 92 48 87 92 93 59 90 93 94

Gulls/Terns 82 96 97 97 58 92 94 94 49 84 92 92 48 87 92 93 59 90 94 94

Piping Plover 9 11 11 11 12 22 23 23 14 23 26 26 14 24 25 25 12 20 21 21

Sea Turtle 

Nesting Habitat I 82 97 97 98 56 89 90 90 – – – – 2 3 3 3 35 47 48 48

Sea Turtle 

Nesting Habitat 

II – – – – – – – – – – – – – – – – – – – –

Sea Turtle 

Sporadic Nesting 

Habitat I – – – – – – – – – – – – – – – – – – – –

Sea Turtle 

Sporadic Nesting 

Habitat II – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-43

Table C-4. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

West Indian 

Manatee Habitat – – – – – – – – – – – – – – – – – – – –

West Indian 

Manatee 

Sporadic Habitat – – – – – – – – – – – – – – – – – – – –

West Indian 

Manatee Rare 

Habitat 82 97 97 98 58 94 96 96 21 28 28 28 2 3 3 3 41 56 56 56

Alabama Beach 

Mouse – – – – – – – – – – – – – – – – – – – –

Perdido Key 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Santa Rosa 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Choctawhatchee 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

St. Andrews 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Southeastern 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Anastasia Island 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Smalltooth 

Sawfish Critical 

Habitat – – – – – – – – – – – – – – – – – – – –

Short Nose 

Sturgeon – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon 

Critical Habitat – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon – – – – – – – – – – – – – – – – – – – –

TX Coastal Bend 

Beach Area 71 81 81 82 43 67 68 68 42 72 77 77 42 75 79 79 49 74 76 76
 C-44 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-4. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

TX Matagorda 

Beach Area 12 16 16 16 16 27 28 28 7 12 14 15 6 12 13 13 10 17 18 18

TX Galveston 

Beach Area – – – – – 1 1 1 – – 1 1 – – 1 1 – – 1 1

TX Sea Rim 

State Park – – – – – – – – – – – – – – – – – – – –

LA Beach Areas – – – – – – – – – – – – – – – – – – – –

AL/MS Gulf 

Islands – – – – – – – – – – – – – – – – – – – –

AL Gulf Shores – – – – – – – – – – – – – – – – – – – –

FL Panhandle 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Big Bend 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Southwest 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Ten Thousand 

Islands Area – – – – – – – – – – – – – – – – – – – –

FL Southeast 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Central East 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Northeast 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Gulf Coast 

Jaguarondi and 

Ocelot 71 81 81 82 43 67 68 68 42 72 77 77 42 75 79 79 49 74 76 76

Louisiana Black 

Bear – – – – – – – – – – – – – – – – – – – –

Northern 

Aplomado 

Falcon 1 1 1 1 – 1 1 1 3 7 8 8 2 5 5 5 1 3 4 4
BOEM-OSRA Catastrophic Run

C-45

Table C-4. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Whooping 

Crane 1 10 12 12 12 5 8 9 9 17 24 27 27 15 26 28 28 12 18 19 19

Whooping 

Crane 2 – – – – – – – – – – – – – – – – – – – –

Wood Stork – – – – – – – – – – – – – – – – – – – –

Alabama Redbellied Turtle – – – – – – – – – – – – – – – – – – – –

Gopher Tortoise 

and Louisiana 

Quillwort – – – – – – – – – – – – – – – – – – – –

Eastern Indigo 

Snake – – – – – – – – – – – – – – – – – – – –

Mississippi 

Gopher Frog – – – – – – – – – – – – – – – – – – – –

Flatwoods 

Salamander – – – – – – – – – – – – – – – – – – – –

Telephus Spurge – – – – – – – – – – – – – – – – – – – –

Mississippi 

Sandhill Crane – – – – – – – – – – – – – – – – – – – –

Everglades Snail 

Kite – – – – – – – – – – – – – – – – – – – –

Cape Sable 

Seaside Sparrow – – – – – – – – – – – – – – – – – – – –

Roseate Tern – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
 C-46 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-5 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make

Contact with an Onshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cameron, TX – – – – – – 2 3 – 1 5 6 – – 3 4 – – 2 3

Willacy, TX – – – – – – 2 3 – – 3 3 – – 2 3 – – 2 2

Kenedy, TX – – – – – – 3 8 – 1 7 9 – 1 9 12 – 1 5 7

Kleberg, TX – 1 1 1 – – 2 3 – 1 4 4 – – 5 6 – – 3 3

Nueces, TX – 1 2 2 – – 1 2 – 1 4 4 – 1 5 6 – 1 3 4

Aransas, TX – 1 3 3 – – 2 3 – 1 4 5 – 1 7 8 – 1 4 5

Calhoun, TX – 5 10 10 – – 5 7 – 2 6 7 – 2 10 13 – 2 8 9

Matagorda, TX – 17 28 28 – 1 9 13 – 3 9 11 – 3 12 15 – 6 14 17

Brazoria, TX – 8 13 13 – 1 6 9 – 1 3 4 – 1 3 5 – 3 6 8

Galveston, TX – 5 16 17 – 1 7 11 – 1 2 2 – 1 2 3 – 2 7 8

Chambers, TX – – – – – – – – – – – – – – – – – – – –

Jefferson, TX – – 10 11 – – 2 4 – – – 1 – – – 1 – – 3 4

Cameron, LA – 1 5 5 – – 4 6 – – – – – – – – – – 2 3

Vermilion, LA – – 1 2 – – 1 2 – – – – – – – – – – 1 1

Iberia, LA – – – – – – – 1 – – – – – – – – – – – –

St. Mary, LA – – – – – – – – – – – – – – – – – – – –

Terrebonne, LA – – – – – – 1 1 – – – – – – – – – – – –

Lafourche, LA – – – – – – – – – – – – – – – – – – – –

Jefferson, LA – – – – – – – – – – – – – – – – – – – –

Plaquemines, LA – – – – – – – 1 – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-47

Table C-5. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

St. Bernard, LA – – – – – – – – – – – – – – – – – – – –

Hancock, MS – – – – – – – – – – – – – – – – – – – –

Harrison, MS – – – – – – – – – – – – – – – – – – – –

Jackson, MS – – – – – – – – – – – – – – – – – – – –

Mobile, AL – – – – – – – – – – – – – – – – – – – –

Baldwin, AL – – – – – – – – – – – – – – – – – – – –

Escambia, FL – – – – – – – – – – – – – – – – – – – –

Santa Rosa, FL – – – – – – – – – – – – – – – – – – – –

Okaloosa, FL – – – – – – – – – – – – – – – – – – – –

Walton, FL – – – – – – – – – – – – – – – – – – – –

Bay, FL – – – – – – – – – – – – – – – – – – – –

Gulf, FL – – – – – – – – – – – – – – – – – – – –

Franklin, FL – – – – – – – – – – – – – – – – – – – –

Wakulla, FL – – – – – – – – – – – – – – – – – – – –

Jefferson, FL – – – – – – – – – – – – – – – – – – – –

Taylor, FL – – – – – – – – – – – – – – – – – – – –

Dixie, FL – – – – – – – – – – – – – – – – – – – –

Levy, FL – – – – – – – – – – – – – – – – – – – –

Citrus, FL – – – – – – – – – – – – – – – – – – – –

Hernando, FL – – – – – – – – – – – – – – – – – – – –

Pasco, FL – – – – – – – – – – – – – – – – – – – –

Pinellas, FL – – – – – – – – – – – – – – – – – – – –

Hillsborough, FL – – – – – – – – – – – – – – – – – – – –

Manatee, FL – – – – – – – – – – – – – – – – – – – –
 C-48 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-5. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sarasota, FL – – – – – – – – – – – – – – – – – – – –

Charlotte, FL – – – – – – – – – – – – – – – – – – – –

Lee, FL – – – – – – – – – – – – – – – – – – – –

Collier, FL – – – – – – – – – – – – – – – – – – – –

Monroe, FL – – – – – – – – – – – – – – – – – – – –

Dade, FL – – – – – – – – – – – – – – – – – – – –

Broward, FL – – – – – – – – – – – – – – – – – – – –

Palm Beach, FL – – – – – – – – – – – – – – – – – – – –

Martin, FL – – – – – – – – – – – – – – – – – – – –

St. Lucie, FL – – – – – – – – – – – – – – – – – – – –

Indian River, FL – – – – – – – – – – – – – – – – – – – –

Brevard, FL – – – – – – – – – – – – – – – – – – – –

Volusia, FL – – – – – – – – – – – – – – – – – – – –

Flagler, FL – – – – – – – – – – – – – – – – – – – –

St. Johns, FL – – – – – – – – – – – – – – – – – – – –

Duval, FL – – – – – – – – – – – – – – – – – – – –

Nassau, FL – – – – – – – – – – – – – – – – – – – –

TX – 39 84 88 – 5 40 66 – 12 47 55 – 9 58 76 – 16 57 71

LA – 1 7 8 – – 7 11 – – – – – – – – – – 3 5

MS – – – – – – – – – – – – – – – – – – – –

AL – – – – – – – – – – – – – – – – – – – –

FL – – – – – – – – – – – – – – – – – – – –

Tamaulipas, 

Mexico – – – – – – 2 5 – – 2 5 – – 2 4 – – 2 4
BOEM-OSRA Catastrophic Run

C-49

Table C-5. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Veracruz-Llave, 

Mexico – – – – – – – 1 – – – – – – – – – – – –

Tabasco, Mexico – – – – – – – – – – – – – – – – – – – –

Campeche, 

Mexico – – – – – – – – – – – – – – – – – – – –

Yucatan, Mexico – – – – – – – – – – – – – – – – – – – –

Quintana Roo, 

Mexico – – – – – – – – – – – – – – – – – – – –

Belize (country) – – – – – – – – – – – – – – – – – – – –

Cuba – – – – – – – – – – – – – – – – – – – –

Passerines – 12 23 24 – 2 20 33 – 8 36 41 – 6 45 58 – 7 31 39

Raptors – 18 46 49 – 3 28 46 – 9 39 45 – 6 48 62 – 9 40 50

Shorebirds – 25 58 61 – 4 33 54 – 9 41 48 – 8 51 66 – 11 46 57

Wading Birds – – – – – – – – – – – – – – – – – – – –

Waterfowl – 19 44 46 – 3 33 51 – 9 39 45 – 6 48 62 – 9 41 51

Diving Birds – 27 64 67 – 4 39 63 – 10 42 49 – 8 52 67 – 12 49 62

Gulls/Terns – 31 73 77 – 4 41 68 – 10 43 51 – 9 54 71 – 14 53 66

Piping Plover – 4 7 7 – 2 15 24 – 3 14 16 – 4 19 24 – 3 14 18

Sea Turtle 

Nesting Habitat I – 39 84 88 – 4 30 45 – – – – – 3 15 23 – 12 32 39

Sea Turtle 

Nesting Habitat 

II – – – – – – – – – – – – – – – – – – – –

Sea Turtle 

Sporadic Nesting 

Habitat I – 1 7 8 – – 7 10 – – – – – – – – – – 3 4

Sea Turtle 

Sporadic Nesting 

Habitat II – – – – – – – – – – – – – – – – – – – –
 C-50 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-5. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

West Indian 

Manatee Habitat – – – – – – – – – – – – – – – – – – – –

West Indian 

Manatee 

Sporadic Habitat – – – – – – – – – – – – – – – – – – – –

West Indian 

Manatee Rare 

Habitat – 40 90 95 – 5 47 74 – 5 13 13 – 3 15 23 – 13 41 51

Alabama Beach 

Mouse – – – – – – – – – – – – – – – – – – – –

Perdido Key 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Santa Rosa 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Choctawhatchee 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

St. Andrews 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Southeastern 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Anastasia Island 

Beach Mouse – – – – – – – – – – – – – – – – – – – –

Smalltooth 

Sawfish Critical 

Habitat – – – – – – – – – – – – – – – – – – – –

Short Nose 

Sturgeon – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon 

Critical Habitat – – – – – – – – – – – – – – – – – – – –

Gulf Sturgeon – – – – – – – 1 – – – – – – – – – – – –

TX Coastal Bend 

Beach Area – 4 7 7 – 1 12 22 – 4 27 31 – 3 31 40 – 3 19 25
BOEM-OSRA Catastrophic Run

C-51

Table C-5. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

TX Matagorda 

Beach Area – 22 38 38 – 1 14 20 – 5 15 17 – 5 22 28 – 8 22 26

TX Galveston 

Beach Area – 13 30 31 – 2 13 20 – 2 6 6 – 2 5 8 – 5 13 16

TX Sea Rim 

State Park – – 10 11 – – 2 4 – – – 1 – – – 1 – – 3 4

LA Beach Areas – 1 5 6 – – 4 6 – – – – – – – – – – 2 3

AL/MS Gulf 

Islands – – – – – – – – – – – – – – – – – – – –

AL Gulf Shores – – – – – – – – – – – – – – – – – – – –

FL Panhandle 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Big Bend 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Southwest 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Ten Thousand 

Islands Area – – – – – – – – – – – – – – – – – – – –

FL Southeast 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Central East 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Northeast 

Beach Area – – – – – – – – – – – – – – – – – – – –

FL Gulf Coast 

Jaguarondi and 

Ocelot – 4 7 7 – 1 12 22 – 4 27 31 – 3 31 40 – 3 19 25

Louisiana Black 

Bear – – – – – – 1 1 – – – – – – – – – – – –

Northern 

Aplomado 

Falcon – – – – – – 3 5 – 1 7 9 – – 5 8 – – 4 6
 C-52 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-5. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Onshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Whooping 

Crane 1 – 3 4 4 – 1 7 10 – 3 10 11 – 3 16 20 – 2 9 11

Whooping 

Crane 2 – – 1 2 – – 1 2 – – – – – – – – – – 1 1

Wood Stork – – – – – – – – – – – – – – – – – – – –

Alabama Redbellied Turtle – – – – – – – – – – – – – – – – – – – –

Gopher Tortoise 

and Louisiana 

Quillwort – – – – – – – – – – – – – – – – – – – –

Eastern Indigo 

Snake – – – – – – – – – – – – – – – – – – – –

Mississippi 

Gopher Frog – – – – – – – – – – – – – – – – – – – –

Flatwoods 

Salamander – – – – – – – – – – – – – – – – – – – –

Telephus Spurge – – – – – – – – – – – – – – – – – – – –

Mississippi 

Sandhill Crane – – – – – – – – – – – – – – – – – – – –

Everglades Snail 

Kite – – – – – – – – – – – – – – – – – – – –

Cape Sable 

Seaside Sparrow – – – – – – – – – – – – – – – – – – – –

Roseate Tern – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
BOEM-OSRA Catastrophic Run

C-53

Table C-6 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make

Contact with an Offshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cayman Islands – – – – – – – – – – – – – – – – – – – –

Bahamas 1 – – – – – – – – – – – – – – – – – – – –

Bahamas 2 – – – – – – – – – – – – – – – – – – – –

Bahamas 3 – – – – – – – – – – – – – – – – – – – –

Bahamas 4 – – – – – – – – – – – – – – – – – – – –

Bahamas 5 – – – – – – – – – – – – – – – – – – – –

Jamaica – – – – – – – – – – – – – – – – – – – –

TX State Waters – 13 24 24 – 10 38 43 – 10 39 43 – 10 44 67 – 11 36 44

West LA State Waters 26 72 80 80 7 35 55 57 8 25 30 33 9 22 27 29 13 38 48 50

East LA State Waters – – – – – – – – – – – – – – – – – – – –

MS State Waters – – – – – – – – – – – – – – – – – – – –

AL State Waters – – – – – – – – – – – – – – – – – – – –

FL Panhandle State 

Waters – – – – – – – 1 – – – – – – – – – – – –

West FL State Waters – – – – – – – – – – – – – – – – – – – –

Tortugas State Waters – – – – – – – – – – – – – – – – – – – –

Southeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Northeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Mexican Waters – – – – – – 1 1 – – – 3 – – – 1 – – – 1
 C-54 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Texas West Waters 

(0-200 m) for EFH – – – – – 1 13 14 – – 14 20 – – 15 28 – 1 11 16

Texas East Waters 

(0-200 m) for EFH 1 20 24 24 4 29 44 46 4 47 60 62 2 47 69 74 3 36 49 52

Louisiana Waters 

West of Mississippi 

River (0-200 m) >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

Louisiana Waters East 

of Mississippi River 

(0-200 m) – – – – – – 1 1 – – – – – – – – – – – –

Mississippi Waters 

(0-200 m) – – – – – – 2 2 – – – – – – – – – – – 1

Alabama Waters 

(0-200 m) – – – – – – 2 2 – – – – – – – – – – – 1

Florida Panhandle 

Waters (0-200 m) – – – – – – 1 2 – – – – – – – – – – – 1

Florida Bend Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Southwest 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Keys Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Southeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Northeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (1) – – – – – – 1 1 – – – 2 – – – 1 – – – 1

Shoreline - 20 m (2) – – – – – – 12 13 – – 9 14 – – 9 25 – – 8 13

Shoreline - 20 m (3) 1 19 24 24 2 18 34 37 1 26 43 45 1 27 51 55 1 22 38 40

Shoreline - 20 m (4) 84 95 96 96 68 82 85 86 55 68 70 71 63 76 78 78 68 80 82 83

Shoreline - 20 m (5) 1 3 4 4 4 11 15 16 – 3 5 6 1 5 7 8 2 6 8 8
BOEM-OSRA Catastrophic Run

C-55

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Shoreline - 20 m (6) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (7) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (8) – – – – – – – 1 – – – – – – – – – – – –

Shoreline - 20 m (9) – – – – – – – 1 – – – – – – – – – – – –

Shoreline - 20 m (10) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (11) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (12) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (13) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (14) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (15) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (1) – – – – – 1 12 12 – – 14 20 – – 15 27 – 1 10 15

20 m - 300 m (2) – 8 10 10 3 20 30 32 3 40 55 57 2 39 62 67 2 27 39 41

20 m - 300 m (3) >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

20 m - 300 m (4) – 1 1 2 1 8 11 12 1 4 9 10 2 7 9 10 1 5 8 8

20 m - 300 m (5) – – – – – – 1 2 – – – – – – – – – – – –

20 m - 300 m (6) – – – – – – 2 2 – – – – – – – – – – – 1

20 m - 300 m (7) – – – – – – 2 2 – – – – – – – – – – – 1

20 m - 300 m (8) – – – – – – 1 2 – – – – – – – – – – – 1

20 m - 300 m (9) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (10) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (11) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (12) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (13) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (14) – – – – – – – – – – – – – – – – – – – –
 C-56 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (1) – – – – – 1 5 5 – 2 13 19 – – 15 23 – 1 8 12

300 m - outer

jurisdiction (2) – – – – – 1 4 4 – 1 11 19 – – 8 12 – – 6 9

300 m - outer

jurisdiction (3) – – – – – 2 5 6 – 8 21 25 – 6 22 27 – 4 12 15

300 m - outer

jurisdiction (4) – – – – – 1 4 4 – 3 16 24 – 2 11 15 – 2 8 11

300 m - outer

jurisdiction (5) – – – – – – 1 2 – – 7 17 – – 5 7 – – 3 6

300 m - outer

jurisdiction (6) – – – – – 2 3 3 1 12 25 27 – 6 14 17 – 5 11 12

300 m - outer

jurisdiction (7) – – – – – – 1 2 – 3 16 20 – 2 8 11 – 1 6 8

300 m - outer

jurisdiction (8) – – – – – – – 1 – 1 9 13 – – 5 7 – – 3 5

300 m - outer

jurisdiction (9) – – – 1 – – 1 2 – 6 15 17 – 5 9 11 – 3 6 8

300 m - outer

jurisdiction (10) – – – – – – 1 2 – 4 14 17 – 3 8 9 – 2 6 7

300 m - outer

jurisdiction (11) – – – – – – 1 1 – 1 10 12 – – 3 5 – – 3 5

300 m - outer

jurisdiction (12) – – – – – 2 4 4 – – 3 5 – 1 3 3 – 1 2 3

300 m - outer

jurisdiction (13) – – – – – 1 2 2 – 1 4 6 – 2 3 4 – 1 2 3

300 m - outer

jurisdiction (14) – – – – – – 1 1 – – 3 5 – – 2 3 – – 1 2

300 m - outer

jurisdiction (15) – – – – – – 2 2 – – – – – – – – – – – 1

300 m - outer

jurisdiction (16) – – – – – – 2 2 – – – 2 – – 1 2 – – 1 2
BOEM-OSRA Catastrophic Run

C-57

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (17) – – – – – – 1 2 – – 1 2 – – 2 3 – – 1 2

300 m - outer

jurisdiction (18) – – – – – – – 1 – – – 1 – – – – – – – –

300 m - outer

jurisdiction (19) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (20) – – – – – – – – – – – 1 – – 1 2 – – – 1

300 m - outer

jurisdiction (21) – – – – – – – – – – – 1 – – – – – – – –

300 m - outer

jurisdiction (22) – – – – – – 1 2 – – – – – – – – – – – 1

300 m - outer

jurisdiction (23) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (24) – – – – – – – – – – – 1 – – 1 2 – – – 1

300 m - outer

jurisdiction (25) – – – – – – – – – – – 1 – – – 1 – – – –

300 m - outer

jurisdiction (26) – – – – – – – – – – – – – – 1 1 – – – –

300 m - outer

jurisdiction (27) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (28) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (29) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (30) – – – – – – – – – – – – – – – – – – – –

North Atlantic Right 

Whale – – – – – – – – – – – – – – – – – – – –

Southeastern SMA – – – – – – – – – – – – – – – – – – – –
 C-58 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sargassum

(March/April) – – – – – – – – – – – – – – 1 1 – – – –

Sargassum

(May/June) – – – – – – – – – – – – – – – – – – – –

Sargassum

(July/August) – – – 1 1 6 10 10 – – – – – – – – – 2 2 3

Seagrass-Wakulla 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Jefferson 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Taylor 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Dixie 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Levy 

County – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (1) – – – – – – – – – – – – – – – 1 – – – –

Topographic 

Features (2) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (3) – – – – – – – – – – – 1 – – – – – – – –

Topographic 

Features (4) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (5) – – – – – – – – – – – – – – – 1 – – – –

Topographic 

Features (6) – – – – – – – – – – – – – – – 1 – – – –

Topographic 

Features (7) – – – – – – – – – – – – – – – 1 – – – –

Topographic 

Features (8) – – – – – – – – – – – – – – – 1 – – – –
BOEM-OSRA Catastrophic Run

C-59

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (9) – – – – – – – – – – – – – – 1 1 – – – –

Topographic 

Features (10) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (11) – – – – – – – – – – – – – – – 1 – – – –

Topographic 

Features (12) – – – – – – – – – – 1 1 – – 2 2 – – 1 1

Stetson Bank – – – – – – – – – – – 1 – – 1 2 – – – 1

Topographic 

Features (13) – – – – – – 1 1 – – 2 2 – – 3 4 – – 2 2

Topographic 

Features (14) – – – – – – – – – – 1 1 – – 1 1 – – – 1

Topographic 

Features (15) – – – – – – 1 1 – 1 2 3 – 1 4 4 – 1 2 2

East Flower Garden 

Bank – – – – – – 1 1 – 2 4 5 – 2 5 6 – 1 3 3

West Flower Garden 

Bank – – – – – 1 1 1 – 2 5 6 – 1 3 4 – 1 2 3

Topographic 

Features (16) – – – – – – – – – 1 3 3 – 1 2 3 – 1 1 2

Topographic 

Features (17) – – – – – – 1 1 – 1 2 3 – 1 2 2 – 1 1 1

Topographic 

Features (18) – – – – – – – – – 1 1 1 – – 1 1 – – 1 1

Topographic 

Features (19) – – – – – – – – – 1 2 2 – 1 1 1 – 1 1 1

Topographic 

Features (20) – – – – – 1 1 1 – 1 3 3 – 1 2 2 – 1 1 2

Topographic 

Features (21) – – – – – – 1 1 – 2 4 5 – 1 2 3 – 1 2 2
 C-60 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (22) – – – – – – – – – – 1 1 – – 1 1 – – – 1

Topographic 

Features (23) – – – – – – – – – 1 3 3 – 1 2 2 – – 1 1

Sonnier Bank – – – – – – 1 1 1 3 3 3 1 2 3 3 1 1 2 2

Topographic 

Features (24) – – – – – – 1 1 1 2 3 3 – 2 2 3 – 1 2 2

Topographic 

Features (25) – – – – – – – – – 1 2 3 – 1 2 2 – 1 1 1

Topographic 

Features (26) – – – – – – – – – 1 2 2 – – 1 1 – – 1 1

Topographic 

Features (27) – – – – – – – 1 – 1 2 2 – 1 2 3 – 1 1 1

Topographic 

Features (28) – – – – – – – – – 1 2 2 – 1 2 2 – 1 1 1

Topographic 

Features (29) – – – – – – – – – – 1 1 – – 1 1 – – – –

Topographic 

Features (30) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (31) – – – – – – – – – – 1 1 – – – – – – – –

Topographic 

Features (32) – – – – – – – 1 – – 1 1 – – 1 1 – – 1 1

Topographic 

Features (33) – – – – – – – 1 – – – – – – – 1 – – – –

Topographic 

Features (34) – – – – – – – – – – – – – – 1 1 – – – –

Topographic 

Features (35) – – – – – – – – – – – – – – – – – – – –

Pinnacle Trend – – – – – – 1 2 – – – – – – – – – – – –

Chandeleur Islands – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-61

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Florida Middle 

Ground – – – – – – – – – – – – – – – – – – – –

Pulley Ridge – – – – – – – – – – – – – – – – – – – –

Madison Swanson – – – – – – – – – – – – – – – – – – – –

Steamboat Lumps – – – – – – – – – – – – – – – – – – – –

Dry Tortugas – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve North – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve South – – – – – – – – – – – – – – – – – – – –

Florida Keys National 

Marine Sanctuary 

(year round) – – – – – – – – – – – – – – – – – – – –

FL State Waters – – – – – – – – – – – – – – – – – – – –

Key Biscayne 

National Park – – – – – – – – – – – – – – – – – – – –

Texas Clipper and 

South Texas Platform – – – – – – 1 2 – – 1 1 – – – – – – – 1

Port Lavaca/Liberty 

Ship Reef – 3 4 4 – 7 16 17 – 7 17 17 – 1 4 4 – 4 10 11

High Island – 8 13 13 1 6 13 14 – 10 15 15 – 1 4 4 – 6 11 11

West Cameron 12 27 30 30 11 31 38 40 12 32 33 33 – 3 4 4 9 23 26 27

Galveston Area 

(GA 393) – – – – – 1 2 2 – – 2 2 – – 1 1 – – 1 1

Cognac Platform 

(MC 194) – – – – – – – – – – – – – – – – – – – –

Horseshoe Rigs 

(MP 306) – – – – – – – – – – – – – – – – – – – –

Vermilion Area >99 >99 >99 >99 >99 >99 >99 >99 66 66 66 66 1 1 1 1 67 67 67 67
 C-62 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Vermilion Area, 

South Addition 3 6 6 6 3 8 9 10 7 11 13 13 – – – – 3 6 7 7

Bay Marchand – – – – – – 1 1 – – – – – – – – – – – –

South Timbalier – 1 1 1 – 6 8 8 – – – – – – – 1 – 2 2 3

South Timbalier Area, 

South Addition – – – – – 2 3 3 – – – – – – – – – 1 1 1

Panhandle FL – – – – – – – 2 – – – – – – – – – – – –

Tampa – – – – – – – – – – – – – – – – – – – –

Southeast FL – – – – – – – – – – – – – – – – – – – –

Daytona Beach – – – – – – – – – – – – – – – – – – – –

Jacksonville – – – – – – – – – – – – – – – – – – – –

Stetson Bank 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

East Flower Garden 

Bank (April-Nov) – – – – – – 1 1 – 1 2 2 – – – – – – 1 1

West Flower Garden 

Bank (April-Nov) – – – – – 1 1 1 – 1 2 2 – – – – – 1 1 1

Chandeleur Islands 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve 1 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve 2 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Florida Keys National 

Marine Sanctuary 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

TX Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-63

Table C-6. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 1 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

LA Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

MS Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

AL Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)1 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)2 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)3 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)4 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)5 (Nov-April) – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
 C-64 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-7 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make

Contact with an Offshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cayman Islands – – – – – – – – – – – – – – – – – – – –

Bahamas 1 – – – – – – – – – – – – – – – – – – – –

Bahamas 2 – – – – – – – – – – – – – – – – – – – –

Bahamas 3 – – – – – – – – – – – – – – – – – – – –

Bahamas 4 – – – – – – – – – – – – – – – – – – – –

Bahamas 5 – – – – – – – – – – – – – – – – – – – –

Jamaica – – – – – – – – – – – – – – – – – – – –

TX State Waters – – – – – – – 2 – – 1 2 – – – 2 – – – 2

West LA State 

Waters – – 1 1 – 1 3 5 – 4 8 8 – 3 9 12 – 2 5 6

East LA State 

Waters 6 15 17 17 13 29 38 41 14 37 42 43 12 30 38 40 11 28 34 35

MS State Waters 12 22 23 23 7 15 18 19 10 18 21 21 11 19 22 24 10 18 21 22

AL State Waters 29 43 46 47 11 22 26 26 13 18 19 20 17 25 27 28 17 27 30 30

FL Panhandle State 

Waters 5 17 23 27 3 13 21 22 1 3 5 5 1 4 6 7 3 9 14 15

West FL State 

Waters – – 2 4 – – – 1 – – – – – – – 1 – – 1 2

Tortugas State 

Waters – – – – – – – – – – – – – – – – – – – –

Southeast FL State 

Waters – – – 1 – – – 1 – – – – – – – 1 – – – 1

Northeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Mexican Waters – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-65

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Texas West Waters 

(0-200 m) for EFH – – – – – – – 2 – – 1 2 – – – 1 – – – 1

Texas East Waters 

(0-200 m) for EFH – – – – – – 1 2 – – 2 3 – – 1 3 – – 1 2

Louisiana Waters 

West of Mississippi 

River (0-200 m) – – 1 1 – 2 4 7 1 7 13 16 – 5 13 17 – 4 8 10

Louisiana Waters 

East of Mississippi 

River (0-200 m) 7 16 18 18 15 30 40 43 19 43 49 50 16 35 44 46 14 31 38 39

Mississippi Waters 

(0-200 m) 30 39 40 41 36 50 57 60 52 67 71 71 46 60 65 66 41 54 58 60

Alabama Waters 

(0-200 m) >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

Florida Panhandle 

Waters (0-200 m) 17 30 34 35 15 36 40 40 6 12 15 15 9 19 22 23 12 24 28 28

Florida Bend Waters 

(0-200 m) – 1 7 9 – 2 6 7 – – 2 2 – 1 2 3 – 1 4 5

Florida Southwest 

Waters (0-200 m) – – 2 2 – – 1 1 – – 1 1 – – – 2 – – 1 2

Florida Keys Waters 

(0-200 m) – – – 1 – – – 1 – – – – – – – 1 – – – 1

Florida Southeast 

Waters (0-200 m) – – – 1 – – – 1 – – – – – – – 1 – – – 1

Florida Northeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (1) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (2) – – – – – – – 1 – – – 1 – – – 1 – – – 1

Shoreline - 20 m (3) – – – – – – – 1 – – 1 1 – – – 1 – – – 1

Shoreline - 20 m (4) – – – – – – 1 2 – – 1 2 – – 1 2 – – 1 1

Shoreline - 20 m (5) – – 1 1 – 1 3 5 – 3 8 9 – 2 9 11 – 2 5 7
 C-66 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Shoreline - 20 m (6) 7 16 17 18 14 29 38 40 17 39 43 44 15 31 39 41 13 29 34 36

Shoreline - 20 m (7) 22 33 34 35 27 42 49 51 33 49 52 53 30 43 48 50 28 42 46 47

Shoreline - 20 m (8) 52 63 66 67 30 43 47 47 26 33 34 35 35 44 46 47 35 46 48 49

Shoreline - 20 m (9) 3 13 21 26 2 10 18 19 – 2 4 4 1 3 5 6 1 7 12 14

Shoreline - 20 m (10) – – 2 5 – – 1 2 – – – – – – – – – – 1 2

Shoreline - 20 m (11) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (12) – – – 1 – – – 1 – – – – – – – 1 – – – 1

Shoreline - 20 m (13) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (14) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (15) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (1) – – – – – – – 2 – – 1 2 – – – 2 – – – 1

20 m - 300 m (2) – – – – – – 1 2 – – 2 3 – – 1 3 – – 1 2

20 m - 300 m (3) – – – – – – 2 3 – 1 3 5 – – 2 4 – – 2 3

20 m - 300 m (4) – – 1 1 – 2 5 7 1 8 13 16 – 5 14 17 – 4 8 10

20 m - 300 m (5) 1 3 5 5 2 5 10 13 3 20 26 28 4 17 24 26 2 11 16 18

20 m - 300 m (6) 21 28 30 30 31 42 49 52 47 62 65 66 40 52 58 60 35 46 51 52

20 m - 300 m (7) >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

20 m - 300 m (8) 16 28 32 32 15 36 39 39 6 12 15 15 9 19 22 23 11 24 27 28

20 m - 300 m (9) – 1 7 9 – 3 7 7 – 1 3 3 – 1 3 5 – 1 5 6

20 m - 300 m (10) – – 2 2 – – 1 1 – – 1 1 – – – 2 – – 1 2

20 m - 300 m (11) – – – 1 – – – 1 – – – – – – – 1 – – – 1

20 m - 300 m (12) – – – 1 – – – 1 – – – – – – – 1 – – – 1

20 m - 300 m (13) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (14) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-67

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (1) – – – – – – – 1 – – – 2 – – – 2 – – – 1

300 m - outer

jurisdiction (2) – – – – – – – 1 – – 1 2 – – – 2 – – – 1

300 m - outer

jurisdiction (3) – – – – – – – 1 – – 1 2 – – – 2 – – – 1

300 m - outer

jurisdiction (4) – – – – – – – 1 – – 1 4 – – – 3 – – – 2

300 m - outer

jurisdiction (5) – – – – – – – – – – 1 3 – – – 3 – – – 2

300 m - outer

jurisdiction (6) – – – – – – – 1 – – 2 5 – – 1 2 – – 1 2

300 m - outer

jurisdiction (7) – – – – – – – 1 – – 1 5 – – 1 4 – – 1 2

300 m - outer

jurisdiction (8) – – – – – – – 1 – – 1 5 – – – 3 – – – 2

300 m - outer

jurisdiction (9) – – – – – – 1 1 – – 3 6 – – 3 5 – – 1 3

300 m - outer

jurisdiction (10) – – – – – – 1 1 – – 4 8 – – 3 6 – – 2 4

300 m - outer

jurisdiction (11) – – – – – – 1 1 – – 3 9 – – 2 5 – – 1 4

300 m - outer

jurisdiction (12) – – 1 1 – 1 2 5 – 6 14 18 – 4 12 15 – 3 7 10

300 m - outer

jurisdiction (13) – – – – – – 1 3 – 3 14 17 – 1 6 10 – 1 5 7

300 m - outer

jurisdiction (14) – – – – – – 1 3 – – 7 12 – – 4 7 – – 3 6

300 m - outer

jurisdiction (15) 1 5 7 7 – 3 7 9 7 23 27 28 7 20 28 30 4 13 17 18

300 m - outer

jurisdiction (16) – 2 4 4 – 1 5 8 2 16 25 26 3 15 24 26 1 9 14 16
 C-68 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (17) – 1 1 1 – – 1 5 – 4 16 17 – 4 15 19 – 2 8 11

300 m - outer

jurisdiction (18) – 1 2 2 – 1 3 6 – 6 16 17 1 8 17 20 – 4 10 11

300 m - outer

jurisdiction (19) – – 2 2 – – 3 6 – 3 12 12 – 4 15 16 – 2 8 9

300 m - outer

jurisdiction (20) – – – – – – – 2 – – 3 6 – – 2 5 – – 1 3

300 m - outer

jurisdiction (21) – – 1 1 – – 2 4 – 1 6 8 – 2 9 10 – 1 5 6

300 m - outer

jurisdiction (22) 1 8 12 12 1 9 15 17 4 14 18 18 5 18 24 24 3 12 17 18

300 m - outer

jurisdiction (23) – – 1 2 – – 2 3 – – 2 4 – 1 5 6 – – 2 4

300 m - outer

jurisdiction (24) – – – 1 – – 1 3 – – 3 7 – – 7 8 – – 3 5

300 m - outer

jurisdiction (25) – – – 1 – – – 1 – – 1 2 – – 1 3 – – 1 2

300 m - outer

jurisdiction (26) – – – – – – – 1 – – 1 3 – – 1 4 – – 1 2

300 m - outer

jurisdiction (27) – – – 1 – – – 1 – – – 1 – – – 1 – – – 1

300 m - outer

jurisdiction (28) – – – – – – – 1 – – – – – – – 1 – – – 1

300 m - outer

jurisdiction (29) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (30) – – – – – – – – – – – – – – – – – – – –

North Atlantic Right 

Whale – – – – – – – – – – – – – – – – – – – –

Southeastern SMA – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-69

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sargassum

(March/April) – – – – – – – – – – – – – – – 1 – – – –

Sargassum

(May/June) – – – – – – – – – – – – – – – – – – – –

Sargassum

(July/August) – – 1 1 – – 3 4 – – – – – – – – – – 1 1

Seagrass-Wakulla 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Jefferson 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Taylor 

County – – – 1 – – – – – – – – – – – – – – – –

Seagrass-Dixie 

County – – 1 1 – – – – – – – – – – – – – – – –

Seagrass-Levy 

County – – – 1 – – – – – – – – – – – – – – – –

Topographic 

Features (1) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (2) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (3) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (4) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (5) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (6) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (7) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (8) – – – – – – – – – – – – – – – – – – – –
 C-70 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (9) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (10) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (11) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (12) – – – – – – – – – – – – – – – – – – – –

Stetson Bank – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (13) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (14) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (15) – – – – – – – – – – – – – – – – – – – –

East Flower Garden 

Bank – – – – – – – – – – – 1 – – – – – – – –

West Flower Garden 

Bank – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (16) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (17) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (18) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (19) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (20) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (21) – – – – – – – – – – – 1 – – – – – – – –
BOEM-OSRA Catastrophic Run

C-71

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (22) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (23) – – – – – – – – – – – – – – – – – – – –

Sonnier Bank – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (24) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (25) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (26) – – – – – – – – – – – – – – – – – – – –

Topographic Features 

(27) – – – – – – – – – – – 1 – – – 1 – – – –

Topographic 

Features (28) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (29) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (30) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (31) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (32) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (33) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (34) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (35) – – – – – – – – – – – 1 – – – – – – – –

Pinnacle Trend 7 13 15 15 5 13 19 20 24 36 38 38 25 38 42 42 15 25 28 29

Chandeleur Islands 6 14 15 15 12 25 31 33 13 28 30 31 11 24 30 31 11 23 27 28
 C-72 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Florida Middle 

Ground – – – 1 – – – 1 – – – – – – – – – – – 1

Pulley Ridge – – 1 2 – – – 1 – – – 1 – – – 1 – – – 1

Madison Swanson – 1 3 4 – 1 2 3 – 1 2 2 – 1 2 2 – 1 2 3

Steamboat Lumps – – 1 1 – – – 1 – – – 1 – – 1 1 – – – 1

Dry Tortugas – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve North – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve South – – – 1 – – – – – – – – – – – 1 – – – –

Florida Keys 

National Marine 

Sanctuary 

(year round) – – – 2 – – – 1 – – – – – – – 1 – – – 1

FL State Waters – – – – – – – – – – – – – – – – – – – –

Key Biscayne 

National Park – – – – – – – – – – – – – – – – – – – –

Texas Clipper and 

South Texas Platform – – – – – – – – – – – – – – – – – – – –

Port Lavaca/Liberty 

Ship Reef – – – – – – – 1 – – – – – – – – – – – –

High Island – – – – – – – – – – 1 1 – – – – – – – –

West Cameron – – – – – – – – – – – – – – – – – – – –

Galveston Area 

(GA 393) – – – – – – – – – – – – – – – – – – – –

Cognac Platform 

(MC 194) – – – – – – – 1 – 1 1 1 – – – – – – 1 1

Horseshoe Rigs 

(MP 306) – – 1 1 – – 1 2 1 2 2 2 – 1 1 1 – 1 1 1

Vermilion Area – – – – – – 1 2 – – 1 1 – – – – – – – 1
BOEM-OSRA Catastrophic Run

C-73

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Vermilion Area, 

South Addition – – – – – – – 1 – – 1 1 – – – – – – – 1

Bay Marchand – – – – – – – – – – – – – – – – – – – –

South Timbalier – – – – – – 2 3 – 1 2 2 – – – 1 – – 1 2

South Timbalier 

Area, South Addition – – – – – – 1 2 – – 2 2 – – – – – – 1 1

Panhandle FL 6 17 23 24 5 20 24 25 1 3 4 4 – – 1 1 3 10 13 14

Tampa – – – 1 – – – – – – – – – – – – – – – –

Southeast FL – – – – – – – 1 – – – – – – – – – – – –

Daytona Beach – – – – – – – – – – – – – – – – – – – –

Jacksonville – – – – – – – – – – – – – – – – – – – –

Stetson Bank 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

East Flower Garden 

Bank (April-Nov) – – – – – – – – – – – – – – – – – – – –

West Flower Garden 

Bank (April-Nov) – – – – – – – – – – – – – – – – – – – –

Chandeleur Islands 

(April-Nov) 6 14 15 15 12 25 31 33 10 20 21 21 – 1 3 4 7 15 18 18

Tortugas Ecological 

Reserve 1 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve 2 

(April-Nov) – – – 1 – – – – – – – – – – – – – – – –

Florida Keys 

National Marine 

Sanctuary 

(April-Nov) – – – 2 – – – 1 – – – – – – – – – – – 1
 C-74 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-7. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 2 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

TX Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

MS Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

AL Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)1 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)2 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)3 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)4 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)5 (Nov-April) – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
BOEM-OSRA Catastrophic Run

C-75

Table C-8 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make 

Contact with an Offshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cayman Islands – – – – – – – – – – – – – – – – – – – –

Bahamas 1 – – – – – – – – – – – – – – – – – – – –

Bahamas 2 – – – – – – – – – – – – – – – – – – – –

Bahamas 3 – – – – – – – – – – – – – – – – – – – –

Bahamas 4 – – – – – – – – – – – – – – – – – – – –

Bahamas 5 – – – – – – – – – – – – – – – – – – – –

Jamaica – – – – – – – – – – – – – – – – – – – –

TX State Waters – – 15 19 – – 8 32 – – 10 22 – – 13 45 – – 11 30

West LA State Waters – 15 50 54 – 2 7 12 – 1 3 6 – 2 9 13 – 5 17 21

East LA State Waters – 1 3 3 – – 1 2 – – – 1 – – 1 1 – – 1 2

MS State Waters – – 1 1 – – – – – – – – – – – – – – – –

AL State Waters – – 1 2 – – – – – – – – – – – – – – – 1

FL Panhandle State 

Waters – – 3 5 – – – 1 – – – – – – – – – – 1 2

West FL State Waters – – – 2 – – – 2 – – – – – – – 1 – – – 1

Tortugas State Waters – – – 1 – – – – – – – – – – – 1 – – – –

Southeast FL State 

Waters – – – – – – – 2 – – – – – – – 1 – – – 1

Northeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Mexican Waters – – – – – – 1 5 – – – 5 – – – 2 – – – 3
 C-76 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Texas West Waters 

(0-200 m) for EFH – – 1 1 – – 7 23 – – 10 22 – – 4 24 – – 6 18

Texas East Waters 

(0-200 m) for EFH – 1 18 21 – 2 18 33 – 1 20 33 – – 27 47 – 1 21 33

Louisiana Waters 

West of Mississippi 

River (0-200 m) 14 57 75 79 3 18 38 47 2 13 25 33 4 25 47 55 6 28 46 53

Louisiana Waters 

East of Mississippi 

River (0-200 m) – 2 7 8 – – 2 3 – – – – – – 2 2 – 1 3 3

Mississippi Waters 

(0-200 m) – 2 8 9 – – 2 3 – – – – – – 1 1 – – 3 3

Alabama Waters 

(0-200 m) – 2 8 10 – – 2 3 – – – – – – 1 1 – – 3 4

Florida Panhandle 

Waters (0-200 m) – 1 7 9 – – 1 2 – – – – – – 1 1 – – 2 3

Florida Bend Waters 

(0-200 m) – – 1 5 – – 1 3 – – – – – – 1 1 – – 1 2

Florida Southwest 

Waters (0-200 m) – – – 3 – – 2 4 – – – 1 – – 1 3 – – 1 2

Florida Keys Waters 

(0-200 m) – – – 1 – – 1 2 – – – 1 – – – 2 – – – 2

Florida Southeast 

Waters (0-200 m) – – – – – – 1 2 – – – – – – – 1 – – – 1

Florida Northeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (1) – – – – – – 1 4 – – – 3 – – – 1 – – – 2

Shoreline - 20 m (2) – – 1 1 – – 3 19 – – 5 12 – – 3 21 – – 3 13

Shoreline - 20 m (3) – – 16 20 – 1 8 18 – – 7 16 – – 13 30 – – 11 21

Shoreline - 20 m (4) – 6 28 30 – 1 6 11 – 1 3 5 – – 9 13 – 2 12 15

Shoreline - 20 m (5) 1 20 39 41 – 2 8 12 – 2 3 4 – 3 8 11 – 7 15 17
BOEM-OSRA Catastrophic Run

C-77

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Shoreline - 20 m (6) – 1 3 3 – – 1 2 – – – – – – – 1 – – 1 1

Shoreline - 20 m (7) – – 2 3 – – 1 1 – – – – – – – – – – 1 1

Shoreline - 20 m (8) – – 2 2 – – – 1 – – – – – – – – – – – 1

Shoreline - 20 m (9) – – 3 5 – – – 1 – – – – – – – – – – 1 2

Shoreline - 20 m 

(10) – – – 1 – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(11) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(12) – – – 1 – – 1 2 – – – – – – – 2 – – – 1

Shoreline - 20 m 

(13) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(14) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(15) – – – – – – – – – – – – – – – 1 – – – –

20 m - 300 m (1) – – 1 1 – – 7 23 – – 10 22 – – 4 24 – – 6 18

20 m - 300 m (2) – 1 14 16 – 2 19 32 – 1 21 36 – – 27 46 – 1 20 33

20 m - 300 m (3) 1 20 36 39 1 11 28 37 – 11 23 32 – 14 39 47 – 14 32 39

20 m - 300 m (4) 17 52 63 65 4 16 30 35 3 7 10 12 5 20 29 32 7 24 33 36

20 m - 300 m (5) – 3 7 8 – – 2 3 – – – – – 1 2 2 – 1 3 3

20 m - 300 m (6) – 2 8 10 – – 2 3 – – – – – – 1 2 – 1 3 4

20 m - 300 m (7) – 2 9 11 – – 2 3 – – – – – – 1 1 – – 3 4

20 m - 300 m (8) – 1 7 10 – – 1 2 – – – – – – 1 1 – – 2 4

20 m - 300 m (9) – – 1 6 – – 2 5 – – – – – – 1 1 – – 1 3

20 m - 300 m (10) – – – 3 – – 2 4 – – – 1 – – 1 4 – – 1 3

20 m - 300 m (11) – – – 1 – – 1 3 – – – 1 – – – 2 – – – 2
 C-78 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

20 m - 300 m (12) – – – 1 – – – 2 – – – 1 – – – 2 – – – 1

20 m - 300 m (13) – – – – – – – 1 – – – – – – – – – – – –

20 m - 300 m (14) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (1) – – – 1 – – 8 20 – – 11 25 – – 4 20 – – 6 17

300 m - outer

jurisdiction (2) – – – 2 – – 9 22 – – 13 27 – – 4 17 – – 7 17

300 m - outer

jurisdiction (3) – – 3 5 – – 9 19 – 1 18 31 – – 12 25 – – 11 20

300 m - outer

jurisdiction (4) – – 1 3 – 1 16 28 – 1 23 38 – – 12 28 – 1 13 24

300 m - outer

jurisdiction (5) – – 1 3 – 1 14 26 – 2 17 30 – – 9 23 – 1 10 21

300 m - outer

jurisdiction (6) – 6 12 14 – 3 19 27 – 10 27 38 – 8 31 42 – 6 22 30

300 m - outer

jurisdiction (7) – 4 11 14 – 7 27 34 – 13 36 44 – 5 30 40 – 7 26 33

300 m - outer

jurisdiction (8) – 2 8 11 – 10 27 36 – 15 37 45 – 3 23 31 – 7 24 31

300 m - outer

jurisdiction (9) 20 37 45 46 9 26 39 43 9 20 26 31 10 34 47 50 12 29 39 43

300 m - outer

jurisdiction (10) 24 37 44 45 32 50 63 66 42 55 63 67 39 59 67 71 34 50 59 62

300 m - outer

jurisdiction (11) 3 13 19 21 6 30 44 48 17 44 60 63 8 29 44 47 8 29 42 45

300 m - outer

jurisdiction (12) 42 56 61 63 14 26 35 38 8 12 13 14 18 27 32 34 21 31 35 37

300 m - outer

jurisdiction (13) >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

300 m - outer

jurisdiction (14) 18 23 26 27 29 42 47 49 48 60 63 64 36 47 50 52 33 43 47 48
BOEM-OSRA Catastrophic Run

C-79

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (15) 2 7 14 17 – 1 6 7 – – – – – 1 4 5 – 3 6 7

300 m - outer

jurisdiction (16) 4 17 22 23 6 17 26 27 – 2 2 3 4 10 14 16 3 11 16 17

300 m - outer

jurisdiction (17) 3 13 19 19 9 20 27 29 2 8 14 17 6 14 19 21 5 14 20 22

300 m - outer

jurisdiction (18) – 4 10 12 – 5 10 12 – 1 1 2 – 1 3 5 – 3 6 8

300 m - outer

jurisdiction (19) – 2 5 9 – 2 6 8 – – 1 1 – 1 3 4 – 1 4 5

300 m - outer

jurisdiction (20) – 2 5 8 – 5 10 12 – 1 5 8 – 5 9 10 – 3 7 10

300 m - outer

jurisdiction (21) – – 3 6 – 1 3 5 – – – 1 – – 2 3 – – 2 3

300 m - outer

jurisdiction (22) – 1 7 12 – – 3 5 – – – 1 – – 2 2 – – 3 5

300 m - outer

jurisdiction (23) – – 1 5 – – 4 7 – – – 1 – – 1 3 – – 2 4

300 m - outer

jurisdiction (24) – 1 5 9 – 3 11 13 – 1 5 8 – 4 9 11 – 2 7 10

300 m - outer

jurisdiction (25) – – 1 3 – – 2 5 – – 1 2 – – 2 6 – – 2 4

300 m - outer

jurisdiction (26) – – 2 4 – – 3 5 – – 2 3 – 1 5 8 – – 3 5

300 m - outer

jurisdiction (27) – – – 1 – – 1 3 – – – 2 – – – 1 – – – 2

300 m - outer

jurisdiction (28) – – – – – – – 1 – – – 1 – – – 1 – – – 1

300 m - outer

jurisdiction (29) – – – – – – – 1 – – – – – – – – – – – –

300 m - outer

jurisdiction (30) – – – – – – – – – – – – – – – – – – – –
 C-80 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

North Atlantic Right 

Whale – – – – – – – – – – – – – – – – – – – –

Southeastern SMA – – – – – – – – – – – – – – – – – – – –

Sargassum

(March/April) – – – – – – – – – – – – – – 1 8 – – – 2

Sargassum

(May/June) – 3 8 10 – – – – – – – – – – – – – 1 2 3

Sargassum

(July/August) 1 1 1 1 66 66 66 66 – – – – – – – – 17 17 17 17

Seagrass-Wakulla 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Jefferson 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Taylor 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Dixie 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Levy 

County – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (1) – – – – – – – – – – – 1 – – – 1 – – – 1

Topographic 

Features (2) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (3) – – – – – – – 1 – – – – – – – – – – – –

Topographic 

Features (4) – – – – – – – – – – – – – – – 1 – – – –

Topographic 

Features (5) – – – – – – – 1 – – – 1 – – – 1 – – – 1

Topographic 

Features (6) – – – – – – – 1 – – – – – – – 1 – – – 1
BOEM-OSRA Catastrophic Run

C-81

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (7) – – – – – – – – – – – – – – – 1 – – – –

Topographic 

Features (8) – – – – – – – – – – – 1 – – – – – – – –

Topographic 

Features (9) – – – – – – – 1 – – – 1 – – – 1 – – – 1

Topographic 

Features (10) – – – – – – – 1 – – – – – – – – – – – –

Topographic 

Features (11) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (12) – – – – – – – 1 – – 1 2 – – – 1 – – – 1

Stetson Bank – – – – – – – – – – – – – – 1 1 – – – –

Topographic 

Features (13) – – – – – – 1 1 – – 1 1 – – 1 1 – – 1 1

Topographic 

Features (14) – – – – – – – – – – 1 1 – – 1 1 – – – 1

Topographic 

Features (15) – – 1 1 – – 1 2 – – 2 3 – – 2 3 – – 1 2

East Flower Garden 

Bank – – 1 1 – – 1 2 – – 3 5 – – 3 5 – – 2 3

West Flower Garden 

Bank – – 1 1 – – 1 2 – – 3 4 – – 3 5 – – 2 3

Topographic 

Features (16) – – – 1 – – – – – – 2 2 – – 2 3 – – 1 1

Topographic 

Features (17) – – – 1 – – – 1 – – 1 2 – – 1 2 – – 1 1

Topographic 

Features (18) – – – – – – – – – – 1 2 – – 1 2 – – 1 1

Topographic 

Features (19) – – 1 1 – – – 1 – – 1 2 – – 2 3 – – 1 2
 C-82 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (20) – – 1 1 – – 1 1 – – 2 3 – – 2 3 – – 1 2

Topographic 

Features (21) – – – 1 – – 2 3 – – 3 4 – – 2 4 – – 2 3

Topographic 

Features (22) – – – – – – – – – – 1 1 – – 1 1 – – – 1

Topographic 

Features (23) – – 1 1 – – 1 2 – – 2 2 – – 2 2 – – 1 2

Sonnier Bank – – 1 1 – – 1 1 – – 1 1 – – 1 2 – – 1 1

Topographic 

Features (24) – 1 1 2 – – 1 1 – – 2 2 – – 3 3 – – 2 2

Topographic 

Features (25) – – 1 1 – – 1 2 – 1 2 2 – 1 2 3 – – 2 2

Topographic 

Features (26) – – – 1 – – 1 1 – – 1 1 – – 2 2 – – 1 1

Topographic 

Features (27) – 1 2 2 – – 2 3 – 1 2 3 – 1 4 5 – 1 2 3

Topographic 

Features (28) – 1 1 2 – – 1 1 – – 1 2 – 1 2 2 – 1 1 2

Topographic 

Features (29) – – 1 1 – – – 1 – – – – – – 1 1 – – 1 1

Topographic 

Features (30) – – – – – – – – – – – 1 – – 1 1 – – – 1

Topographic 

Features (31) – 1 1 1 – – 1 2 – – 1 1 – – 1 1 – – 1 1

Topographic 

Features (32) – 2 2 3 – 1 2 3 – 1 1 1 – – 2 2 – 1 2 2

Topographic 

Features (33) – 1 2 2 – – 2 2 – – – – – – 1 1 – 1 1 1

Topographic 

Features (34) – 1 2 2 – – 1 1 – – – – – 1 1 2 – 1 1 1
BOEM-OSRA Catastrophic Run

C-83

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (35) – – 1 1 – – – – – – – – – – – – – – – –

Pinnacle Trend – 1 7 9 – – 2 2 – – – – – – 1 1 – – 2 3

Chandeleur Islands – – 2 2 – – 1 1 – – – – – – – – – – 1 1

Florida Middle 

Ground – – – 1 – – – – – – – – – – – – – – – –

Pulley Ridge – – – 2 – – 1 2 – – – – – – – 2 – – – 1

Madison Swanson – – 1 1 – – – – – – – – – – – – – – – –

Steamboat Lumps – – – 1 – – – – – – – – – – – – – – – –

Dry Tortugas – – – – – – – – – – – – – – – 1 – – – –

Tortugas Ecological 

Reserve North – – – – – – – – – – – – – – – 1 – – – –

Tortugas Ecological 

Reserve South – – – 1 – – – – – – – – – – – 1 – – – 1

Florida Keys 

National Marine 

Sanctuary 

(year round) – – – 1 – – 1 3 – – – – – – – 2 – – – 2

FL State Waters – – – 1 – – – – – – – – – – – 1 – – – –

Key Biscayne 

National Park – – – – – – – 1 – – – – – – – – – – – –

Texas Clipper and 

South Texas 

Platform – – – – – – 1 5 – – 1 1 – – – – – – – 2

Port Lavaca/Liberty 

Ship Reef – – 6 7 – – 7 14 – – 5 6 – – 5 10 – – 6 9

High Island – – 6 7 – – 3 4 – – 1 1 – – 2 4 – – 3 4

West Cameron – 1 12 14 – 2 4 9 – – 2 2 – – 5 6 – 1 6 8

Galveston Area 

(GA 393) – – 1 1 – – 1 2 – – – 1 – – 1 2 – – 1 1
 C-84 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cognac Platform 

(MC 194) – 1 2 2 – – 1 1 – – – – – – – – – – 1 1

Horseshoe Rigs 

(MP 306) – – 2 2 – – – – – – – – – – – – – – – 1

Vermilion Area – 5 22 24 – 2 9 13 – 1 3 3 – – 5 7 – 2 10 12

Vermilion Area, 

South Addition – 6 13 15 – 3 12 16 – 4 9 9 – – 6 8 – 3 10 12

Bay Marchand – 1 3 3 – – – 1 – – – – – – – 1 – – 1 1

South Timbalier 2 17 27 28 – 2 7 11 – 2 2 2 – 1 2 3 1 5 9 11

South Timbalier 

Area, South 

Addition 7 25 30 31 1 5 11 14 1 3 4 4 – 1 2 3 2 9 12 13

Panhandle FL – – 4 6 – – – 1 – – – – – – – – – – 1 2

Tampa – – – 1 – – – – – – – – – – – – – – – –

Southeast FL – – – – – – – 1 – – – – – – – – – – – –

Daytona Beach – – – – – – – – – – – – – – – – – – – –

Jacksonville – – – – – – – – – – – – – – – – – – – –

Stetson Bank 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

East Flower Garden 

Bank (April-Nov) – – 1 1 – – 1 2 – – 2 2 – – 1 2 – – 1 2

West Flower Garden 

Bank (April-Nov) – – 1 1 – – 1 2 – – 2 2 – – 1 2 – – 1 2

Chandeleur Islands 

(April-Nov) – – 2 2 – – 1 1 – – – – – – – – – – 1 1

Tortugas Ecological 

Reserve 1 

(April-Nov) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-85

Table C-8. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 3 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Tortugas Ecological 

Reserve 2 

(April-Nov) – – – 1 – – – – – – – – – – – – – – – –

Florida Keys 

National Marine 

Sanctuary 

(April-Nov) – – – 1 – – 1 3 – – – – – – – 1 – – – 1

TX Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

MS Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

AL Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)1 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)2 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)3 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)4 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)5 (Nov-April) – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
 C-86 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-9 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make 

Contact with an Offshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cayman Islands – – – – – – – – – – – – – – – – – – – –

Bahamas 1 – – – – – – – – – – – – – – – – – – – –

Bahamas 2 – – – – – – – – – – – – – – – – – – – –

Bahamas 3 – – – – – – – – – – – – – – – – – – – –

Bahamas 4 – – – – – – – – – – – – – – – – – – – –

Bahamas 5 – – – – – – – – – – – – – – – – – – – –

Jamaica – – – – – – – – – – – – – – – – – – – –

TX State Waters 97 >99 >99 >99 88 >99 >99 >99 76 94 99 99 77 97 99 99 84 98 99 99

West LA State 

Waters – – – – – – – – – – – – – – – – – – – –

East LA State 

Waters – – – – – – – – – – – – – – – – – – – –

MS State Waters – – – – – – – – – – – – – – – – – – – –

AL State Waters – – – – – – – – – – – – – – – – – – – –

FL Panhandle State 

Waters – – – – – – – – – – – – – – – – – – – –

West FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Tortugas State 

Waters – – – – – – – – – – – – – – – – – – – –

Southeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Northeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Mexican Waters – – – – – – – – – 1 1 1 – 1 1 1 – 1 1 1
BOEM-OSRA Catastrophic Run

C-87

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Texas West Waters 

(0-200m) for EFH >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

Texas East Waters 

(0-200 m) for EFH 1 2 2 2 4 5 5 5 1 5 6 6 1 5 6 6 2 4 5 5

Louisiana Waters 

West of Mississippi 

River (0-200 m) – – – – – – – – – – – 1 – – – – – – – –

Louisiana Waters 

East of Mississippi 

River (0-200 m) – – – – – – – – – – – – – – – – – – – –

Mississippi Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Alabama Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Panhandle 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Bend Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Southwest 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Keys Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Southeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Northeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (1) – – – – – – – – – 1 1 1 – 1 1 1 – – 1 1

Shoreline - 20 m (2) 95 99 99 99 84 96 97 97 70 92 96 96 73 96 98 98 81 96 98 98

Shoreline - 20 m (3) 1 2 2 2 2 5 5 5 – 2 4 4 – 3 3 3 1 3 3 3

Shoreline - 20 m (4) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (5) – – – – – – – – – – – – – – – – – – – –
 C-88 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Shoreline - 20 m (6) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (7) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (8) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (9) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(10) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(11) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(12) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(13) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(14) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m 

(15) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (1) >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

20 m - 300 m (2) 1 1 1 1 3 4 4 4 1 5 6 7 1 5 5 5 1 3 4 4

20 m - 300 m (3) – – – – – – – – – – – 1 – – – – – – – –

20 m - 300 m (4) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (5) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (6) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (7) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (8) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (9) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (10) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (11) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-89

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

20 m - 300 m (12) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (13) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (14) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (1) – – – – – – – – 1 3 5 5 1 2 3 3 1 2 2 2

300 m - outer

jurisdiction (2) – – – – – – – – – 1 2 2 – 1 2 2 – – 1 1

300 m - outer

jurisdiction (3) – – – – – – – – – – – 1 – – 1 1 – – – –

300 m - outer

jurisdiction (4) – – – – – – – – – – 1 1 – – 2 2 – – 1 1

300 m - outer

jurisdiction (5) – – – – – – – – – – – 1 – – 1 1 – – – 1

300 m - outer

jurisdiction (6) – – – – – – – – – – – 1 – – – 1 – – – –

300 m - outer

jurisdiction (7) – – – – – – – – – – – 1 – – 1 1 – – – –

300 m - outer

jurisdiction (8) – – – – – – – – – – – – – – 1 1 – – – –

300 m - outer

jurisdiction (9) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (10) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (11) – – – – – – – – – – – – – – – 1 – – – –

300 m - outer

jurisdiction (12) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (13) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (14) – – – – – – – – – – – – – – – – – – – –
 C-90 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (15) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (16) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (17) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (18) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (19) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (20) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (21) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (22) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (23) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (24) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (25) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (26) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (27) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (28) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (29) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (30) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-91

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

North Atlantic Right 

Whale – – – – – – – – – – – – – – – – – – – –

Southeastern SMA – – – – – – – – – – – – – – – – – – – –

Sargassum

(March/April) – – – – – – – – – – – – – – – – – – – –

Sargassum

(May/June) – – – – – – – – – – – – – – – – – – – –

Sargassum

(July/August) – – – – – – – – – – – – – – – – – – – –

Seagrass-Wakulla 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Jefferson 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Taylor 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Dixie 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Levy 

County – – – – – – – – – – – – – – – – – – – –

Topographic

Features (1) – – – – – – – – – 1 1 1 1 1 1 1 – – – –

Topographic 

Features (2) – – – – – – – – – – – – – 1 1 1 – – – –

Topographic 

Features (3) – – – – – – – – – 1 1 1 – – 1 1 – – – –

Topographic 

Features (4) – – – – – – – – 1 1 1 1 1 1 1 1 – 1 1 1

Topographic 

Features (5) – – – – – – – – 1 2 2 2 1 2 2 2 – 1 1 1

Topographic 

Features (6) – – – – – – – – 1 1 1 1 – 1 1 1 – 1 1 1
 C-92 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (7) – – – – – – – – 1 1 1 1 – 1 1 1 – – 1 1

Topographic 

Features (8) – – – – – – – – – 1 1 1 – – – – – – – –

Topographic 

Features (9) – – – – – – – – – 1 2 2 – – – – – – 1 1

Topographic 

Features (10) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (11) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (12) – – – – – – – – – – – – – – – – – – – –

Stetson Bank – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (13) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (14) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (15) – – – – – – – – – – – – – – – – – – – –

East Flower Garden 

Bank – – – – – – – – – – – – – – – – – – – –

West Flower Garden 

Bank – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (16) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (17) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (18) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (19) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-93

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (20) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (21) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (22) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (23) – – – – – – – – – – – – – – – – – – – –

Sonnier Bank – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (24) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (25) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (26) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (27) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (28) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (29) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (30) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (31) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (32) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (33) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (34) – – – – – – – – – – – – – – – – – – – –
 C-94 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (35) – – – – – – – – – – – – – – – – – – – –

Pinnacle Trend – – – – – – – – – – – – – – – – – – – –

Chandeleur Islands – – – – – – – – – – – – – – – – – – – –

Florida Middle 

Ground – – – – – – – – – – – – – – – – – – – –

Pulley Ridge – – – – – – – – – – – – – – – – – – – –

Madison Swanson – – – – – – – – – – – – – – – – – – – –

Steamboat Lumps – – – – – – – – – – – – – – – – – – – –

Dry Tortugas – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve North – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve South – – – – – – – – – – – – – – – – – – – –

Florida Keys 

National Marine 

Sanctuary 

(year round) – – – – – – – – – – – – – – – – – – – –

FL State Waters – – – – – – – – – – – – – – – – – – – –

Key Biscayne 

National Park – – – – – – – – – – – – – – – – – – – –

Texas Clipper and 

South Texas 

Platform – 1 1 1 – – – – – 1 1 1 – – – – – – – –

Port Lavaca/Liberty 

Ship Reef – – – – – – – – – – – – – – – – – – – –

High Island – – – – – – – – – – – – – – – – – – – –

West Cameron – – – – – – – – – – – – – – – – – – – –

Galveston Area 

(GA 393) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-95

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cognac Platform 

(MC 194) – – – – – – – – – – – – – – – – – – – –

Horseshoe Rigs 

(MP 306) – – – – – – – – – – – – – – – – – – – –

Vermilion Area – – – – – – – – – – – – – – – – – – – –

Vermilion Area, 

South Addition – – – – – – – – – – – – – – – – – – – –

Bay Marchand – – – – – – – – – – – – – – – – – – – –

South Timbalier – – – – – – – – – – – – – – – – – – – –

South Timbalier 

Area, South 

Addition – – – – – – – – – – – – – – – – – – – –

Panhandle FL – – – – – – – – – – – – – – – – – – – –

Tampa – – – – – – – – – – – – – – – – – – – –

Southeast FL – – – – – – – – – – – – – – – – – – – –

Daytona Beach – – – – – – – – – – – – – – – – – – – –

Jacksonville – – – – – – – – – – – – – – – – – – – –

Stetson Bank 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

East Flower Garden 

Bank (April-Nov) – – – – – – – – – – – – – – – – – – – –

West Flower Garden 

Bank (April-Nov) – – – – – – – – – – – – – – – – – – – –

Chandeleur Islands 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve 1 

(April-Nov) – – – – – – – – – – – – – – – – – – – –
 C-96 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-9. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 4 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Tortugas Ecological 

Reserve 2 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Florida Keys 

National Marine 

Sanctuary 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

TX Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

MS Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

AL Gulf State 

Waters (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)1 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)2 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)3 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)4 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)5 (Nov-April) – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 
BOEM-OSRA Catastrophic Run

C-97

Table C-10 

Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make 

Contact with an Offshore Environmental Resource within the Specified Number of Days

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Cayman Islands – – – – – – – – – – – – – – – – – – – –

Bahamas 1 – – – – – – – – – – – – – – – – – – – –

Bahamas 2 – – – – – – – – – – – – – – – – – – – –

Bahamas 3 – – – – – – – – – – – – – – – – – – – –

Bahamas 4 – – – – – – – – – – – – – – – – – – – –

Bahamas 5 – – – – – – – – – – – – – – – – – – – –

Jamaica – – – – – – – – – – – – – – – – – – – –

TX State Waters – 47 87 90 – 8 44 69 – 18 53 58 – 16 63 80 – 22 62 74

West LA State 

Waters – 1 7 8 – – 8 12 – – – 2 – – – – – – 4 5

East LA State Waters – – – – – – – – – – – – – – – – – – – –

MS State Waters – – – – – – – – – – – – – – – – – – – –

AL State Waters – – – – – – – – – – – – – – – – – – – –

FL Panhandle State 

Waters – – – – – – – – – – – – – – – – – – – –

West FL State Waters – – – – – – – – – – – – – – – – – – – –

Tortugas State 

Waters – – – – – – – – – – – – – – – – – – – –

Southeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Northeast FL State 

Waters – – – – – – – – – – – – – – – – – – – –

Mexican Waters – – – – – – 4 7 – – 6 10 – – 4 8 – – 4 6
 C-98 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Texas West Waters 

(0-200 m) for EFH 1 16 22 23 – 8 29 40 2 31 55 59 1 32 55 66 1 22 40 47

Texas East Waters 

(0-200 m) for EFH 60 86 92 94 30 54 67 73 36 54 60 62 38 60 67 73 41 63 72 75

Louisiana Waters 

West of Mississippi 

River (0-200 m) 1 9 13 15 2 27 42 43 – 3 5 7 – 2 5 9 1 10 16 18

Louisiana Waters 

East of Mississippi 

River (0-200 m) – – – – – – – 1 – – – – – – – – – – – –

Mississippi Waters 

(0-200 m) – – – – – – – 1 – – – – – – – – – – – –

Alabama Waters 

(0-200 m) – – – – – – – 1 – – – – – – – – – – – –

Florida Panhandle 

Waters (0-200 m) – – – – – – – 1 – – – – – – – – – – – –

Florida Bend Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Southwest 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Keys Waters 

(0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Southeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Florida Northeast 

Waters (0-200 m) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (1) – – – – – – 3 6 – – 4 7 – – 3 6 – – 3 5

Shoreline - 20 m (2) – 12 20 20 – 3 20 32 – 9 37 42 – 8 45 58 – 8 31 38

Shoreline - 20 m (3) – 49 75 77 – 10 33 45 – 12 20 23 – 10 22 28 – 20 38 43

Shoreline - 20 m (4) – 3 8 10 – 1 15 20 – – 1 2 – – – 1 – 1 6 8

Shoreline - 20 m (5) – – – 1 – – 3 5 – – – 1 – – – – – – 1 2
BOEM-OSRA Catastrophic Run

C-99

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Shoreline - 20 m (6) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (7) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (8) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (9) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (10) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (11) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (12) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (13) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (14) – – – – – – – – – – – – – – – – – – – –

Shoreline - 20 m (15) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (1) 1 15 21 21 – 9 29 39 2 32 56 59 1 33 55 65 1 22 40 46

20 m - 300 m (2) 64 87 93 94 37 60 71 76 39 57 62 64 41 63 70 75 45 67 74 77

20 m - 300 m (3) 1 8 11 13 3 28 41 42 – 3 5 7 – 2 6 9 1 10 16 18

20 m - 300 m (4) – – – 1 – 1 8 9 – – 1 2 – – 1 1 – – 3 3

20 m - 300 m (5) – – – – – – 1 1 – – – – – – – – – – – –

20 m - 300 m (6) – – – – – – – 1 – – – – – – – – – – – –

20 m - 300 m (7) – – – – – – – 1 – – – – – – – – – – – –

20 m - 300 m (8) – – – – – – – 1 – – – – – – – – – – – –

20 m - 300 m (9) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (10) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (11) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (12) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (13) – – – – – – – – – – – – – – – – – – – –

20 m - 300 m (14) – – – – – – – – – – – – – – – – – – – –
 C-100 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (1) 15 27 31 32 5 18 32 38 28 64 76 78 20 47 59 65 17 39 49 53

300 m - outer

jurisdiction (2) 10 18 22 22 10 24 34 38 43 66 73 75 23 40 50 53 21 37 45 47

300 m - outer

jurisdiction (3) 85 92 93 93 72 81 85 85 63 67 69 70 69 77 80 82 72 79 82 83

300 m - outer

jurisdiction (4) >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99 >99

300 m - outer

jurisdiction (5) – 3 6 6 4 14 20 25 1 9 20 26 3 14 21 27 2 10 17 21

300 m - outer

jurisdiction (6) 4 6 8 9 11 22 29 29 – 3 6 9 – 7 14 15 4 9 14 15

300 m - outer

jurisdiction (7) 1 4 5 6 6 13 18 20 – 1 5 9 – 10 18 19 2 7 12 14

300 m - outer

jurisdiction (8) – 2 3 4 – 3 8 11 – – 4 7 – 6 15 18 – 3 8 10

300 m - outer

jurisdiction (9) – – 1 2 – 3 10 11 – – 2 4 – 1 4 5 – 1 4 6

300 m - outer

jurisdiction (10) – 1 2 3 – 4 9 10 – – 3 5 – 2 8 9 – 2 6 7

300 m - outer

jurisdiction (11) – – 1 2 – 1 4 6 – – 2 5 – 2 10 12 – 1 4 6

300 m - outer

jurisdiction (12) – – – 1 – – 4 5 – – 1 2 – – 1 1 – – 1 2

300 m - outer

jurisdiction (13) – – – 1 – – 3 4 – – 1 1 – – 1 2 – – 1 2

300 m - outer

jurisdiction (14) – – – 1 – – 2 3 – – 1 1 – – 1 2 – – 1 2

300 m - outer

jurisdiction (15) – – – – – – 1 3 – – – – – – – – – – – 1

300 m - outer

jurisdiction (16) – – – – – – 2 3 – – – 1 – – – – – – 1 1
BOEM-OSRA Catastrophic Run

C-101

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

300 m - outer

jurisdiction (17) – – – – – – 2 3 – – – 1 – – 1 1 – – 1 1

300 m - outer

jurisdiction (18) – – – – – – 1 1 – – – 1 – – – – – – – 1

300 m - outer

jurisdiction (19) – – – – – – – 1 – – – 1 – – – – – – – –

300 m - outer

jurisdiction (20) – – – – – – – 1 – – – 1 – – – – – – – 1

300 m - outer

jurisdiction (21) – – – – – – – 1 – – – 1 – – – – – – – –

300 m - outer

jurisdiction (22) – – – – – – – 1 – – – – – – – – – – – –

300 m - outer

jurisdiction (23) – – – – – – – 1 – – – – – – – – – – – –

300 m - outer

jurisdiction (24) – – – – – – – 1 – – – – – – – 1 – – – 1

300 m - outer

jurisdiction (25) – – – – – – – – – – – 1 – – – – – – – –

300 m - outer

jurisdiction (26) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (27) – – – – – – – – – – – 1 – – – – – – – –

300 m - outer

jurisdiction (28) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (29) – – – – – – – – – – – – – – – – – – – –

300 m - outer

jurisdiction (30) – – – – – – – – – – – – – – – – – – – –

North Atlantic Right 

Whale – – – – – – – – – – – – – – – – – – – –

Southeastern SMA – – – – – – – – – – – – – – – – – – – –
 C-102 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Sargassum

(March/April) – – 1 1 – – – – – – – – – 2 7 9 – 1 2 3

Sargassum

(May/June) 67 67 67 67 – – – – – – – – – – – – 17 17 17 17

Sargassum

(July/August) 1 1 1 1 66 66 66 66 – – – – – – – – 17 17 17 17

Seagrass-Wakulla 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Jefferson 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Taylor 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Dixie 

County – – – – – – – – – – – – – – – – – – – –

Seagrass-Levy 

County – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (1) – – – – – – – 1 – – 2 2 – – 2 2 – – 1 1

Topographic 

Features (2) – – – – – – – – – – 1 1 – – 1 1 – – – 1

Topographic 

Features (3) – – – – – – – – – – 1 2 – – 1 2 – – 1 1

Topographic 

Features (4) – – – – – – – 1 – – 1 1 – – 1 2 – – 1 1

Topographic 

Features (5) – – – – – – 1 1 – 1 2 2 – – 2 3 – – 1 2

Topographic 

Features (6) – – 1 1 – – – 1 – – 1 2 – – 1 2 – – 1 1

Topographic 

Features (7) – – – – – – 1 1 – – 1 1 – – 1 1 – – 1 1

Topographic 

Features (8) – – – – – – – – – – 1 1 – – 1 1 – – 1 1
BOEM-OSRA Catastrophic Run

C-103

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (9) – – 1 1 – – 1 1 – 1 2 2 – 1 2 2 – 1 1 1

Topographic 

Features (10) – – 1 1 – – 1 1 – – 1 1 – 1 1 2 – – 1 1

Topographic 

Features (11) – – – – – – 1 1 – – 1 1 – 1 2 2 – – 1 1

Topographic 

Features (12) 1 3 3 3 1 2 2 2 1 2 2 3 – 2 3 3 1 2 3 3

Stetson Bank – 2 2 2 – 1 1 1 – – – 1 – – 1 1 – 1 1 1

Topographic 

Features (13) – 1 1 1 – 1 2 3 – – 1 1 – – 1 1 – 1 1 1

Topographic 

Features (14) – 1 1 1 1 1 2 2 – 1 1 1 – 1 1 1 – 1 1 1

Topographic 

Features (15) 1 2 2 2 – 3 4 4 – 1 1 1 – 1 1 2 – 2 2 2

East Flower Garden 

Bank 1 2 2 2 4 7 8 8 1 1 2 3 – 1 3 4 1 3 4 4

West Flower Garden 

Bank – 1 1 2 2 7 8 9 – – 1 2 – – 2 3 1 2 3 4

Topographic 

Features (16) – – – – – 3 4 4 – – – 1 – – – 1 – 1 1 2

Topographic 

Features (17) – 1 1 1 – 1 1 2 – – – – – – – 1 – 1 1 1

Topographic

Features (18) – – 1 1 – 1 2 2 – – – – – – – 1 – 1 1 1

Topographic 

Features (19) – – – 1 – 2 3 3 – – – 1 – – – 1 – 1 1 1

Topographic 

Features (20) – 1 1 1 – 3 4 4 – 1 1 1 – – – 1 – 1 2 2

Topographic 

Features (21) – – – – – 3 4 5 – – 1 1 – – 1 1 – 1 1 2
 C-104 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Topographic 

Features (22) – – – – – – 1 1 – – – 1 – – – – – – – –

Topographic 

Features (23) – – – – – – 2 2 – – 1 1 – – 1 1 – – 1 1

Sonnier Bank – – – – – – 1 1 – – – – – – – – – – – –

Topographic 

Features (24) – – – – – 1 2 2 – – 1 1 – – – – – – 1 1

Topographic 

Features (25) – – – – – – 2 2 – – – – – – – – – – 1 1

Topographic 

Features (26) – – – – – 1 2 2 – – 1 1 – – – – – – 1 1

Topographic 

Features (27) – – – – – – 2 2 – – – 1 – – – – – – 1 1

Topographic 

Features (28) – – – – – – 1 1 – – – – – – – – – – – –

Topographic 

Features (29) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (30) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (31) – – – – – – – 1 – – – – – – – – – – – –

Topographic 

Features (32) – – – – – – 1 1 – – – – – – – – – – – –

Topographic 

Features (33) – – – – – – 1 1 – – – – – – – – – – – –

Topographic 

Features (34) – – – – – – – – – – – – – – – – – – – –

Topographic 

Features (35) – – – – – – – – – – – – – – – – – – – –

Pinnacle Trend – – – – – – – 1 – – – – – – – – – – – –

Chandeleur Islands – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-105

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Florida Middle 

Ground – – – – – – – – – – – – – – – – – – – –

Pulley Ridge – – – – – – – – – – – – – – – – – – – –

Madison Swanson – – – – – – – – – – – – – – – – – – – –

Steamboat Lumps – – – – – – – – – – – – – – – – – – – –

Dry Tortugas – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve North – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve South – – – – – – – – – – – – – – – – – – – –

Florida Keys National 

Marine Sanctuary 

(year round) – – – – – – – – – – – – – – – – – – – –

FL State Waters – – – – – – – – – – – – – – – – – – – –

Key Biscayne 

National Park – – – – – – – – – – – – – – – – – – – –

Texas Clipper and 

South Texas Platform – – – – – 1 5 8 – 2 5 6 – – – – – 1 3 4

Port Lavaca/Liberty 

Ship Reef 6 27 34 35 – 7 18 23 1 7 8 8 – 1 2 3 2 10 15 17

High Island – 7 19 20 – 2 9 15 – 1 1 1 – – – – – 3 7 9

West Cameron – 4 7 9 – 5 17 22 – – – – – – – 1 – 2 6 8

Galveston Area 

(GA 393) – 2 3 3 – 1 2 3 – – 1 1 – – 1 1 – 1 2 2

Cognac Platform 

(MC 194) – – – – – – – 1 – – – – – – – – – – – –

Horseshoe Rigs 

(MP 306) – – – – – – – – – – – – – – – – – – – –

Vermilion Area – – 3 4 – 1 12 14 – – – – – – – – – – 4 5
 C-106 Central Planning Area Lease Sales 235, 241, and 247 EIS

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

Vermilion Area, 

South Addition – 1 3 4 – 8 17 18 – – – – – – – – – 2 5 6

Bay Marchand – – – – – – – – – – – – – – – – – – – –

South Timbalier – – – – – – 3 4 – – – – – – – – – – 1 1

South Timbalier Area, 

South Addition – – – 1 – – 5 5 – – – – – – – – – – 1 1

Panhandle FL – – – – – – – – – – – – – – – – – – – –

Tampa – – – – – – – – – – – – – – – – – – – –

Southeast FL – – – – – – – – – – – – – – – – – – – –

Daytona Beach – – – – – – – – – – – – – – – – – – – –

Jacksonville – – – – – – – – – – – – – – – – – – – –

Stetson Bank 

(April-Nov) – 2 2 2 – 1 1 1 – – – – – – – – – 1 1 1

East Flower Garden 

Bank (April-Nov) 1 2 2 2 4 7 8 8 – – 1 1 – – – – 1 2 3 3

West Flower Garden 

Bank (April-Nov) – 1 1 2 2 7 8 9 – – – – – – – – 1 2 3 3

Chandeleur Islands 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve 1 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Tortugas Ecological 

Reserve 2 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

Florida Keys National 

Marine Sanctuary 

(April-Nov) – – – – – – – – – – – – – – – – – – – –

TX Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –
BOEM-OSRA Catastrophic Run

C-107

Table C-10. Conditional Probabilities (expressed as percent chance) that an Oil Spill Occurring at Launch Point 5 Will Make Contact with an Offshore 

Environmental Resource within the Specified Number of Days (continued). 

Season Spring Summer Fall Winter Annual

Days 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60 3 10 30 60

Resource Percent Chance

LA Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

LA Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

MS Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

AL Gulf State Waters 

(Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)1 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)2 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)3 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)4 (Nov-April) – – – – – – – – – – – – – – – – – – – –

FL (East Coast and 

Gulf)5 (Nov-April) – – – – – – – – – – – – – – – – – – – –

Note: Values of <0.5% are indicated by “–”. 

APPENDIX D 

 

RECENT PUBLICATIONS OF THE ENVIRONMENTAL STUDIES 

PROGRAM, GULF OF MEXICO OCS REGION, 2006–PRESENT

Recent Publications of the Environmental Studies Program D-3 

D. RECENT PUBLICATIONS OF THE ENVIRONMENTAL STUDIES 

PROGRAM, GULF OF MEXICO OCS REGION, 2006–PRESENT

Published in 2013

Study Number Title

BOEM 2013-0111

Socioeconomic Responses to Coastal Land Loss and Hurricanes: Measuring 

Resilience among Outer Continental Shelf Related Coastal Communities in 

Louisiana

BOEM 2013-01110 Meteorological and Wave Measurements for Improving Meteorological 

Modeling

BOEM 2013-0112 Offshore Drilling Industry and Rig Construction Market in the Gulf of Mexico

BOEM 2013-0113

BOEM 2013-0114

Energy Market and Infrastructure Information for Evaluating Renewable

Energy Projects for the Atlantic and Pacific OCS Regions

Volume I: Technical Report

Volume II: Appendices

BOEM 2013-01157 South Atlantic Information Resources: Data Search and Literature Synthesis

BOEM 2013-0120 Platform Recruited Reef Fish, Phase II: Do Platforms Provide Habitat that 

Increases the Survival of Reef Fishes?

BOEM 2013-0123

Short-Term Movement, Home Range, and Behavior of Red Snapper around 

Petroleum Platforms in the Northern Gulf of Mexico, as Determined by High 

Resolution Acoustic Telemetry

BOEM 2013-216 Corals on Oil and Gas Platforms near the Flower Garden Banks: Population 

Characteristics, Recruitment, and Genetic Affinity

BOEM 2013-217 Deepwater Coral Distribution and Abundance on Active Offshore Oil and Gas 

Platforms and Decommissioned “Rigs-to-Reefs” Platforms

BOEM 2013-222 Improving the Predictive Capability of 3-D Seismic Surface Amplitude Data for 

Identifying Chemosynthetic Communities

Published in 2012

Study Number Title

BOEM 2012-004 Ultra-Deepwater Circulation Processes in the Gulf of Mexico

BOEM 2012-006

BOEM 2012-007

Evaluation of Visual Impact on Cultural Resources/Historic Properties: 

North Atlantic, Mid-Atlantic, and Florida Straits

Volume I: Technical Report of Findings

Volume II: Appendices

BOEM 2012-008 Inventory and Analysis of Archaeological Site Occurrence on the Atlantic OCS

BOEM 2012-015 Seismic Survey Mitigation Measures and Marine Mammal Observer Reports

BOEM 2012-071 Long-Term Trends in Environmental Parameters along the 

Louisiana/Mississippi Outer Continental Shelf using Remote Sensing Data
D-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

BOEM 2012-102 Gulf of Mexico MAG-PLAN 2012: Updated and Revised Economic Impact 

Model

BOEM 2012-106

Exploration and Research of Northern Gulf of Mexico Deepwater Natural and 

Artificial Hard-Bottom Habitats, with Emphasis on Coral Communities: Reefs, 

Rigs, and Wrecks-“Lophelia II” Interim Report

BOEM 2012-107 Proceedings: Twenty-Sixth Gulf of Mexico Information Transfer Meeting

BOEM 2012-108 Integrated Bio-Physical Modeling of Louisiana-Texas (Latex) Shelf

BOEM 2012-109 Literature Search and Data Synthesis for Marine Mammals and Sea Turtles in 

the US Atlantic from Maine to the Florida Keys

Published in 2011

Study Number Title

BOEMRE 2011-001 Analysis of the Oil Services Contract Industry in the Gulf of Mexico Region

BOEMRE 2011-002

Status and Applications of Acoustic Mitigation and Monitoring Systems for 

Marine Mammals: Workshop Proceedings, November 17-19, 2009, Boston, 

Massachusetts

BOEMRE 2011-003 Impact of Recent Hurricane Activity on Historic Shipwrecks in the 

Gulf of Mexico Outer Continental Shelf

BOEMRE 2011-004 Archival Investigations for Potential Colonial-Era Shipwrecks in 

Ultra-Deepwater within the Gulf of Mexico

BOEMRE 2011-011 User’s Guide for the 2011 Gulfwide Offshore Activities Data System 

(GOADS-2011)

BOEMRE 2011-012 Literature Synthesis for the North and Central Atlantic Ocean

BOEMRE 2011-028 Assessment of Opportunities for Alternative Uses of Hydrocarbon 

Infrastructure in the Gulf of Mexico

BOEMRE 2011-040 Shipwreck Research in the New Orleans Notarial Archives

BOEM 2011-043

BOEM 2011-044

OCS-Related Infrastructure Fact Book

Volume I: Post-Hurricane Impact Assessment

Volume II: Communities in the Gulf of Mexico

BOEM 2011-054 Diversifying Energy Industry Risk in the Gulf of Mexico: Post-2004 Changes 

in Offshore Oil and Gas Insurance Markets

Published in 2010

Study Number Title

MMS 2010-001 Proceedings: USA-Mexico Workshop on the Deepwater Physical 

Oceanography of the Gulf of Mexico, June 2007

MMS 2010-002 Proof of Concept for Platform Recruited Reef Fish, Phase 1: Do Platforms 

Provide Habitat for Subadult Red Snapper?

MMS 2010-007 Assessment of Marginal Production in the Gulf of Mexico and Lost Production 

from Early Decommissioning
Recent Publications of the Environmental Studies Program D-5 

MMS 2010-015 Low-Frequency Variability of Currents in the Deepwater Eastern Gulf of 

Mexico

MMS 2010-016 Trophic Aspects of Sperm Whales (Physeter macrocephalus) in the Northern 

Gulf of Mexico Using Stable Isotopes of Carbon and Nitrogen

BOEMRE 2010-039 Bank Erosion of Navigation Canals in the Western and Central Gulf of Mexico

BOEMRE 2010-041 Study of Deepwater Currents in the Eastern Gulf of Mexico

BOEMRE 2010-042 Fact Book: Offshore Oil and Gas Industry Support Sectors

BOEMRE 2010-043 Determination of Net Flux of Reactive Volatile Organic Compounds 

at the Air-Water Interface in the Gulf of Mexico

BOEMRE 2010-044 Full-Water Column Current Observations in the Western Gulf of Mexico

BOEMRE 2010-045 Year 2008 Gulfwide Emission Inventory Study

BOEMRE 2010-046 Multicomponent and Multifrequency Seismic for Assessment of Fluid-Gas 

Expulsion Geology and Gas-Hydrate Deposits: Gulf of Mexico Hydrates

BOEMRE 2010-050 Satellite Data Assimilation into Meteorological/Air Quality Models

BOEMRE 2010-051 Evaluation of NASA Aura’s Data Products for Use in Air Quality Studies over 

the Gulf of Mexico

BOEMRE 2010-052

BOEMRE 2010-053

Long-Term Monitoring at the East and West Flower Garden Banks: 2004-2008

Volume 1: Technical Report

Volume 2: Appendices

Published in 2009

Study Number Title

MMS 2009-010 Quality Control and Analysis of Acoustic Doppler Current Profiler Data 

Collected on Offshore Platforms of the Gulf of Mexico

MMS 2009-013 Foraminiferal Communities of Bathyal Hydrocarbon Seeps, Northern 

Gulf of Mexico: A Taxonomic, Ecologic, and Geologic Study

MMS 2009-023 Loop Current Frontal Eddies Based on Satellite Remote Sensing and Drifter 

Data

MMS 2009-032 Post-Hurricane Assessment of Sensitive Habitats of the Flower Garden Banks 

Vicinity

MMS 2009-039 Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology 

Study: Final Report

MMS 2009-043

Blue Crab (Callinectes sapidus) Use of the Ship/Trinity/Tiger Shoal Complex as 

a Nationally Important Spawning/Hatching/Foraging Ground: Discovery, 

Evaluation, and Sand Mining Recommendations Based on Blue Crab, Shrimp, 

and Spotted Seatrout Findings

MMS 2009-046 Investigations of Chemosynthetic Communities on the Lower Continental Slope 

of the Gulf of Mexico, Interim Report 2
D-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

MMS 2009-048

Outer Continental Shelf (OCS)-Related Pipelines and Navigation Canals in the 

Western and Central Gulf of Mexico: Relative Impacts on Wetlands Habitats 

and Effectiveness of Mitigation

MMS 2009-050 Observation of the Deepwater Manifestation of the Loop Current and Loop 

Current Rings in the Eastern Gulf of Mexico

MMS 2009-051 Proceedings: Twenty-Fifth Gulf of Mexico Information Transfer Meeting, 

January 2009

MMS 2009-055

MMS 2009-056

MMS 2009-057

MMS 2009-058

Synthesis, Analysis, and Integration of Meteorological and Air Quality Data for 

the Gulf of Mexico Region

Volume I: User’s Manual for the Gulf of Mexico Air Quality Database 

(Version 1.0)

Volume II: Technical Reference Manual for the Gulf of Mexico Air Quality 

Database

Volume III: Data Analysis

Volume IV: Cart Analysis of Modeling Episode Days

MMS 2009-059 Evaluation of Oil and Gas Platforms on the Louisiana Continental Shelf for 

Organisms with Biotechnology Potential

MMS 2009-060 Modeling Waves and Currents Produced by Hurricanes Katrina, Rita, and 

Wilma

Published in 2008

Study Number Title

MMS 2008-001 Deepwater Currents in the Eastern Gulf of Mexico: Observations at 25.5°N 

and 87°W

MMS 2008-006 Sperm Whale Seismic Study in the Gulf of Mexico: Synthesis Report

MMS 2008-009 Investigations of Chemosynthetic Communities on the Lower Continental Slope 

of the Gulf of Mexico: Interim Report 1

MMS 2008-012 Proceedings: Twenty-Fourth Gulf of Mexico Information Transfer Meeting, 

January 2007

MMS 2008-015

Characterization of Northern Gulf of Mexico Deepwater Hard Bottom 

Communities with Emphasis on Lophelia Coral—Lophelia Reef Megafaunal 

Community Structure, Biotopes, Genetics, Microbial Ecology, and Geology 

(2004-2006)

NOTE: This study was conducted by the U.S. Geological Survey (USGS) for 

the Agency’s Headquarters’ Office, and it was funded by USGS.

MMS 2008-017 Examination of the Development of Liquefied Natural Gas on the Gulf of 

Mexico

MMS 2008-018 Viosca Knoll Wreck: Discovery and Investigation of an Early NineteenthCentury Wooden Sailing Vessel in 2,000 Feet of Water
Recent Publications of the Environmental Studies Program D-7 

MMS 2008-019 Post-Hurricane Assessment at the East Flower Garden Bank Long-Term 

Monitoring Site: November 2005

MMS 2008-022 Effects of Subsea Processing on Deepwater Environments in the Gulf of Mexico

MMS 2008-024 Executive Summary: 3rd International Deep-Sea Coral Symposium in Miami

MMS 2008-027

MMS 2008-028

Long-Term Monitoring at the East and West Flower Garden Banks, 

2004-2005—Interim Report

Volume I: Technical Report

Volume II: Appendices

MMS 2008-029 Five-Year Meteorological Datasets for CALMET/CALPUFF and OCD5 

Modeling of the Gulf of Mexico Region

MMS 2008-030

MMS 2008-031

Study of Deepwater Currents in the Northwestern Gulf of Mexico

Volume I: Executive Summary

Volume II: Technical Report

MMS 2008-042

MMS 2008-043

MMS 2008-044

MMS 2008-045

MMS 2008-046

MMS 2008-047

History of the Offshore Oil and Gas Industry in Southern Louisiana

Volume I: Papers on the Evolving Offshore Industry

Volume II: Bayou Lafourche—Oral Histories of the Oil and Gas Industry

Volume III: Morgan City’s History in the Era of Oil and Gas—Perspectives of 

Those Who Were There

Volume IV: Terrebonne Parish

Volume V: Guide to the Interviews

Volume VI: A Collection of Photographs

MMS 2008-048

Platform Debris Fields Associated with the Blue Dolphin (Buccaneer) Gas and 

Oil Field Artificial Reef Sites Offshore Freeport, Texas: Extent, Composition, 

and Biological Utilization

MMS 2008-050

MMS 2008-051

Labor Needs Survey

Volume I: Technical Report

Volume II: Survey Instruments

MMS 2008-052 Benefits and Burdens of OCS Activities on States, Labor Market Areas, Coastal 

Counties, and Selected Communities

MMS 2008-058 Cumulative Increment Analysis for the Breton National Wilderness Area

Published in 2007

Study Number Title

MMS 2007-015 Archaeological and Biological Analysis of World War II Shipwrecks in the 

Gulf of Mexico; Artificial Reef Effect in Deepwater

MMS 2007-019 Mixtures of Metals and Polynuclear Aromatic Hydrocarbons May Elicit 

Complex, Nonadditive Toxicological Interactions

MMS 2007-022 Full-Water Column Current Observations in the Central Gulf of Mexico: 

Final Report
D-8 Central Planning Area Lease Sales 235, 241, and 247 EIS

MMS 2007-030 Incorporation of Gulf of Mexico Benthic Survey Data into the Ocean 

Biogeographic Information System

MMS 2007-031 Idle Iron in the Gulf of Mexico

MMS 2007-033 Cooperative Research to Study Dive Patterns of Sperm Whales in the Atlantic 

Ocean

MMS 2007-034 Competition and Performance in Oil and Gas Lease Sales and Development 

in the U.S. Gulf of Mexico OCS Region, 1983-1999

MMS 2007-035

Seafloor Characteristics and Distribution Patterns of Lophelia pertusa and 

Other Sessile Megafauna at Two Upper-Slope Sites in the Northeastern 

Gulf of Mexico

MMS 2007-044 Characterization of Northern Gulf of Mexico Deepwater Hard-Bottom 

Communities with Emphasis on Lophelia Coral

MMS 2007-056

Full-Water Column Currents Near the Sigsbee Escarpment (91-92o W. 

Longitude) and Relationships with the Loop Current and Associated Warm- and 

Cold-Core Eddies

MMS 2007-061 Study of Barite Solubility and the Release of Trace Components to the Marine 

Environment

MMS 2007-067 Year 2005 Gulfwide Emission Inventory Study

MMS 2007-068 User’s Guide for the 2008 Gulfwide Offshore Activities Data System 

(GOADS-2008)

Published in 2006

Study Number Title

MMS 2006-005 Fidelity of Red Snapper to Petroleum Platforms and Artificial Reefs in the 

Northern Gulf of Mexico

MMS 2006-011 Sustainable Community in Oil and Gas Country: Final Report

MMS 2006-028 Degradation of Synthetic-Based Drilling Mud Base Fluids by Gulf of Mexico 

Sediments, Final Report

MMS 2006-030 Accounting for Socioeconomic Change from Offshore Oil and Gas: Cumulative 

Effects on Louisiana’s Coastal Parishes, 1969-2000

MMS 2006-034 Sperm Whale Seismic Study in the Gulf of Mexico, Summary Report: 

2002-2004

MMS 2006-035 Long-Term Monitoring at the East and West Flower Garden Banks National 

Marine Sanctuary, 2002-2003

MMS 2006-036 Study to Conduct National Register of Historic Places Evaluations of 

Submerged Sites on the Gulf of Mexico Outer Continental Shelf
Recent Publications of the Environmental Studies Program D-9 

MMS 2006-037

Effect of Depth, Location, and Habitat Type, on Relative Abundance and 

Species Composition of Fishes Associated with Petroleum Platforms and 

Sonnier Bank in the Northern Gulf of Mexico

MMS 2006-044

MMS 2006-045

MMS 2006-046

Effects of Oil and Gas Exploration and Development at Selected Continental 

Slope Sites in the Gulf of Mexico

Volume I: Executive Summary 

Volume II: Technical Report 

Volume III: Appendices

MMS 2006-063 Economic Effects of Petroleum Prices and Production in the Gulf of Mexico 

OCS on the U.S. Gulf Coast Economy

MMS 2006-064 Capital Investment Decisionmaking and Trends in Petroleum Resource 

Development in the U.S. Gulf of Mexico

MMS 2006-067 Sperm Whale Seismic Study in the Gulf of Mexico, Annual Report: 

Years 3 and 4

MMS 2006-071

Annotated Bibliography of the Potential Environmental Impacts of Chlorination 

and Disinfection Byproducts Relevant to Offshore Liquefied Natural Gas Port 

Facilities

MMS 2006-072 Mica Shipwreck Project Report: Deepwater Archaeological Investigation of a 

19th Century Shipwreck in the Gulf of Mexico

MMS 2006-073

MMS 2006-074

Exploratory Study of Deepwater Currents in the Gulf of Mexico

Volume I: Executive Summary

Volume II: Technical Report

KEYWORD INDEX

Keyword Index Keywords-3 

KEYWORD INDEX

Air Quality, viii, x, xi, 1-10, 2-6, 2-7, 2-8, 3-10, 4-6, 4-8, 4-9, 4-10, 4-11, 4-12, 4-13, 4-14, 4-15, 4-16, 

4-103, 4-124, 4-125, 4-129, 4-164, 4-211, 4-215, 5-4 

Alternative Energy, 4-18, 4-19, 4-24

Archaeological Resources, x, xiv, 1-11, 2-6, 2-7, 2-9, 4-8, 4-165, 4-166, 4-167, 4-168, 4-169, 4-170, 

4-171, 4-172, 4-173, 4-174, 4-175, 4-176, 4-211, 4-216, 4-217

Artificial Reefs, xiv, 1-10, 2-6, 3-25, 3-28, 3-29, 4-142, 4-144, 4-150, 4-152, 4-158, 4-159, 4-160, 4-167, 

4-168, 4-169, 4-170, 4-173, 4-174, 4-175, 4-218

Beach Mice, x, xiii, 2-7, 2-9, 4-119, 4-120, 4-121, 4-122, 4-211

Blowout Preventer, 1-7, 3-21, 3-22

Blowouts, viii, xiii, xiv, xv, 1-7, 2-10, 3-21, 3-22, 4-24, 4-30, 4-48, 4-53, 4-54, 4-55, 4-56, 4-57, 4-58, 

4-60, 4-61, 4-62, 4-63, 4-65, 4-66, 4-68, 4-72, 4-73, 4-74, 4-75, 4-77, 4-79, 4-80, 4-81, 4-82, 4-85, 

4-86, 4-88, 4-90, 4-92, 4-93, 4-102, 4-142, 4-146, 4-150, 4-151, 4-153, 4-154, 4-155, 4-173, 4-189, 

4-209, 4-210, 4-211, 4-215

Chemosynthetic Communities, xii, 1-10, 1-11, 2-6, 3-9, 4-72, 4-73, 4-74, 4-75, 4-76, 4-77, 4-78, 4-144, 

5-4 

Chemosynthetic Deepwater Benthic Communities, 2-8, 4-71, 4-72, 4-74, 4-141, 4-144, 4-146

Coastal and Marine Birds, x, xiii, 2-7, 2-8, 2-9, 4-5, 4-122, 4-123, 4-124, 4-125, 4-126, 4-127, 4-128, 

4-129, 4-130, 4-132, 4-133, 4-134, 4-135, 4-136, 4-211, 4-215

Coastal Barrier Beaches, x, xi, 2-7, 2-8, 4-30, 4-31, 4-32, 4-35, 4-36, 4-37, 4-38, 4-103, 4-211

Coastal Infrastructure, xiv, 2-7, 2-9, 3-3, 3-13, 3-24, 4-8, 4-39, 4-41, 4-42, 4-44, 4-104, 4-141, 4-166, 

4-177, 4-178, 4-179, 4-180, 4-186, 4-187, 4-189, 4-198

Coastal Spills, 3-12, 3-17, 3-18, 3-19, 4-17, 4-130, 4-138, 4-139, 4-146, 4-154, 4-166, 4-168, 4-172, 

4-182

Coastal Spills, 3-19

Coastal Zone Management, x, 1-4, 1-5, 1-8, 1-11, 4-4, 4-5, 4-36, 4-42, 4-44, 5-4, 5-6, 5-7, 5-8 

Collisions, viii, xiv, xv, 3-22, 4-17, 4-23, 4-31, 4-33, 4-40, 4-46, 4-76, 4-82, 4-94, 4-102, 4-105, 4-110, 

4-115, 4-124, 4-126, 4-127, 4-132, 4-134, 4-136, 4-178, 4-179, 4-189, 4-195, 4-196, 4-215

Commercial Fisheries, x, xiv, 2-7, 2-9, 4-86, 4-97, 4-98, 4-133, 4-149, 4-150, 4-151, 4-152, 4-153, 4-154, 

4-155, 4-156, 4-157, 4-170, 4-176, 4-211, 4-215, 4-216

Commercial Fishing, x, xiii, xiv, 1-10, 2-6, 3-14, 4-20, 4-27, 4-55, 4-57, 4-65, 4-89, 4-90, 4-93, 4-97, 

4-107, 4-110, 4-111, 4-131, 4-136, 4-139, 4-147, 4-150, 4-151, 4-152, 4-153, 4-154, 4-156, 4-158, 

4-160, 4-163, 4-167, 4-169, 4-170, 4-173, 4-175, 4-217, 4-218

Consultation and Coordination, viii, 1-4, 1-6, 3-15

Cumulative Activities, viii, xiii, 3-23, 3-24, 3-25, 3-26, 3-27, 3-28, 3-29, 3-35, 3-37, 4-3, 4-41, 4-103, 

4-118, 4-122, 4-128, 4-129, 4-168, 4-174, 4-209

Cumulative Impacts, viii, xi, xiii, 3-23, 3-25, 3-31, 3-34, 4-3, 4-4, 4-9, 4-13, 4-14, 4-15, 4-16, 4-17, 4-18, 

4-19, 4-20, 4-21, 4-23, 4-24, 4-25, 4-27, 4-28, 4-30, 4-31, 4-36, 4-37, 4-38, 4-39, 4-46, 4-47, 4-49, 

4-52, 4-55, 4-59, 4-62, 4-67, 4-69, 4-71, 4-72, 4-74, 4-76, 4-77, 4-78, 4-79, 4-80, 4-81, 4-82, 4-83, 

4-84, 4-86, 4-87, 4-88, 4-90, 4-92, 4-93, 4-99, 4-102, 4-103, 4-110, 4-111, 4-113, 4-115, 4-118, 4-119, 

4-120, 4-122, 4-124, 4-130, 4-133, 4-134, 4-137, 4-139, 4-140, 4-141, 4-143, 4-144, 4-145, 4-149, 

4-151, 4-155, 4-157, 4-158, 4-161, 4-162, 4-163, 4-165, 4-167, 4-172, 4-173, 4-176, 4-177, 4-178, 

4-186, 4-188, 4-189, 4-191, 4-192, 4-193, 4-194, 4-197, 4-198, 4-203, 4-206, 4-209, 4-212, 4-217, 5-4 
Keywords-4 Central Planning Area Lease Sales 235, 241, and 247 EIS

Deepwater, x, xiv, 1-6, 1-7, 2-7, 2-8, 3-7, 3-10, 3-12, 3-13, 3-15, 3-16, 3-17, 3-20, 3-21, 3-23, 3-27, 3-28, 

3-29, 3-30, 3-35, 3-38, 4-4, 4-5, 4-6, 4-7, 4-9, 4-10, 4-14, 4-16, 4-18, 4-19, 4-21, 4-22, 4-23, 4-24, 4-28, 

4-29, 4-32, 4-33, 4-36, 4-37, 4-39, 4-40, 4-46, 4-47, 4-48, 4-50, 4-51, 4-52, 4-56, 4-58, 4-59, 4-63, 

4-64, 4-66, 4-67, 4-70, 4-71, 4-72, 4-74, 4-75, 4-76, 4-77, 4-78, 4-79, 4-80, 4-81, 4-82, 4-83, 4-88, 

4-91, 4-92, 4-94, 4-96, 4-97, 4-99, 4-100, 4-101, 4-110, 4-111, 4-112, 4-113, 4-114, 4-115, 4-116, 

4-118, 4-122, 4-124, 4-126, 4-134, 4-136, 4-139, 4-140, 4-141, 4-142, 4-143, 4-144, 4-146, 4-148, 

4-149, 4-152, 4-153, 4-155, 4-156, 4-159, 4-165, 4-168, 4-171, 4-176, 4-177, 4-178, 4-179, 4-180, 

4-182, 4-187, 4-188, 4-194, 4-196, 4-197, 4-198, 4-199, 4-200, 4-201, 4-207, 4-208, 4-209, 4-210, 

4-218, 5-4, 5-9 

Deepwater Horizon, x, xiv, 1-6, 1-7, 2-8, 3-12, 3-15, 3-16, 3-17, 3-20, 3-21, 3-27, 3-28, 3-30, 3-38, 4-4, 

4-5, 4-6, 4-7, 4-9, 4-14, 4-16, 4-18, 4-19, 4-21, 4-22, 4-23, 4-24, 4-28, 4-29, 4-32, 4-33, 4-36, 4-37, 

4-39, 4-40, 4-46, 4-47, 4-48, 4-50, 4-51, 4-52, 4-56, 4-58, 4-59, 4-63, 4-64, 4-66, 4-67, 4-70, 4-71, 

4-75, 4-77, 4-81, 4-83, 4-88, 4-91, 4-92, 4-96, 4-97, 4-99, 4-100, 4-101, 4-110, 4-111, 4-112, 4-113, 

4-114, 4-115, 4-116, 4-118, 4-122, 4-124, 4-126, 4-134, 4-136, 4-139, 4-140, 4-141, 4-143, 4-146, 

4-148, 4-149, 4-153, 4-155, 4-156, 4-159, 4-165, 4-171, 4-176, 4-177, 4-178, 4-187, 4-188, 4-194, 

4-196, 4-197, 4-199, 4-200, 4-201, 4-207, 4-208, 4-209, 4-210, 5-4, 5-9 

Demographics, xv, 2-7, 2-9, 4-8, 4-117, 4-188, 4-189, 4-191, 4-194

Diamondback Terrapins, x, xiii, 2-7, 2-9, 4-113, 4-114, 4-115, 4-116, 4-117, 4-118, 4-211

Discharges, x, xi, xii, xiii, 2-9, 3-10, 3-11, 3-12, 3-14, 4-17, 4-18, 4-19, 4-20, 4-22, 4-23, 4-24, 4-25, 4-26, 

4-27, 4-29, 4-52, 4-53, 4-55, 4-57, 4-58, 4-59, 4-60, 4-62, 4-65, 4-66, 4-68, 4-69, 4-70, 4-71, 4-72, 

4-74, 4-75, 4-76, 4-77, 4-78, 4-79, 4-80, 4-82, 4-84, 4-86, 4-90, 4-92, 4-96, 4-102, 4-104, 4-106, 4-107, 

4-123, 4-125, 4-130, 4-134, 4-137, 4-139, 4-140, 4-141, 4-142, 4-145, 4-147, 4-150, 4-152, 4-154, 

4-155, 4-158, 4-208, 4-210, 4-214, 4-215

Dispersants, xiii, 3-17, 4-12, 4-17, 4-18, 4-19, 4-20, 4-22, 4-24, 4-26, 4-27, 4-29, 4-31, 4-32, 4-37, 4-40, 

4-58, 4-60, 4-61, 4-64, 4-66, 4-73, 4-75, 4-76, 4-79, 4-81, 4-82, 4-93, 4-96, 4-138, 4-139, 4-166, 4-168, 

4-195, 4-199, 4-212, 4-214, 4-215

Dunes, x, xi, 2-7, 2-8, 4-30, 4-31, 4-32, 4-33, 4-34, 4-35, 4-36, 4-37, 4-38, 4-45, 4-103, 4-115, 4-116, 

4-117, 4-121, 4-122, 4-133, 4-135, 4-163, 4-184, 4-205, 4-211

Economic Factors, xv, 2-7, 2-9, 4-8, 4-160, 4-162, 4-164, 4-191, 4-192, 4-193, 4-194, 4-197

Employment, xv, 4-161, 4-165, 4-189, 4-190, 4-191, 4-192, 4-193, 4-194, 4-195, 4-197, 4-198, 4-213

Endangered Species Act, 1-4, 1-5, 2-11, 3-11, 4-4, 4-5, 4-7, 4-59, 4-67, 4-95, 4-102, 4-103, 4-106, 4-112, 

4-114, 4-120, 4-215, 5-9 

Environmental Justice, x, xv, 1-6, 2-7, 2-9, 4-8, 4-185, 4-187, 4-194, 4-195, 4-197, 4-198, 4-200, 4-202, 

4-203, 4-204, 4-205, 4-206, 4-207, 4-208, 5-4 

Essential Fish Habitat, x, xiii, 1-5, 2-7, 2-8, 4-5, 4-141, 4-142, 4-143, 4-144, 4-146, 4-147, 4-148, 4-149, 

4-211, 5-9 

Explosive Removals, 4-56, 4-60, 4-64, 4-107, 4-137, 4-139, 4-150, 4-152

Fish Resources, x, xiii, 2-7, 2-8, 4-141, 4-142, 4-143, 4-144, 4-145, 4-146, 4-148, 4-149, 4-155, 4-158, 

4-211, 4-215, 4-216

Fisheries, xiv, 1-11, 2-8, 4-5, 4-76, 4-81, 4-95, 4-108, 4-109, 4-117, 4-124, 4-131, 4-133, 4-140, 4-148, 

4-149, 4-151, 4-152, 4-153, 4-154, 4-155, 4-156, 4-159, 4-160, 4-161, 4-195, 4-197, 4-199, 5-3, 5-6, 

5-7, 5-9 

Flaring, 1-11, 4-12, 4-13, 4-14

Flower Garden Banks, 2-6, 4-64, 4-65, 4-144, 4-146

Gulf Sturgeon, x, xiii, 2-7, 2-8, 4-137, 4-138, 4-139, 4-140, 4-141, 4-211

Human Resources, 2-7, 2-9, 4-177, 4-211
Keyword Index Keywords-5 

Hurricanes, x, 3-26, 3-29, 3-35, 3-36, 3-37, 3-39, 4-13, 4-14, 4-15, 4-18, 4-19, 4-20, 4-22, 4-26, 4-27, 

4-33, 4-35, 4-36, 4-38, 4-39, 4-40, 4-41, 4-44, 4-45, 4-46, 4-50, 4-51, 4-55, 4-57, 4-58, 4-62, 4-64, 

4-66, 4-69, 4-70, 4-71, 4-88, 4-89, 4-90, 4-98, 4-109, 4-117, 4-119, 4-120, 4-121, 4-122, 4-126, 4-133, 

4-135, 4-136, 4-143, 4-154, 4-159, 4-164, 4-167, 4-169, 4-170, 4-173, 4-175, 4-192, 4-193, 4-197, 

4-204, 4-205, 4-209

Income, xv, 4-164, 4-189, 4-190, 4-191, 4-193, 4-195, 4-196, 4-197, 4-198, 4-199, 4-200, 4-201, 4-202, 

4-203, 4-204, 4-205, 4-206, 4-207, 4-208

Infrastructure, vii, x, xii, xiii, xiv, xv, 1-9, 2-7, 3-3, 3-4, 3-9, 3-13, 3-22, 3-24, 3-25, 3-26, 3-27, 3-32, 

3-38, 3-39, 4-15, 4-30, 4-32, 4-34, 4-38, 4-39, 4-40, 4-44, 4-48, 4-49, 4-52, 4-59, 4-60, 4-80, 4-84, 

4-115, 4-125, 4-128, 4-136, 4-137, 4-144, 4-150, 4-153, 4-157, 4-158, 4-161, 4-162, 4-163, 4-164, 

4-168, 4-169, 4-174, 4-175, 4-177, 4-178, 4-179, 4-180, 4-181, 4-182, 4-184, 4-185, 4-186, 4-187, 

4-193, 4-195, 4-197, 4-198, 4-202, 4-203, 4-204, 4-205, 4-206, 4-207, 4-208, 4-209, 4-213, 4-215, 

4-218

Land Use, x, xiv, 2-7, 2-9, 3-14, 3-32, 4-8, 4-117, 4-138, 4-140, 4-161, 4-177, 4-178, 4-179, 4-180, 

4-181, 4-182, 4-183, 4-184, 4-186, 4-187, 4-188, 4-193, 4-198, 4-202, 4-211

Live Bottoms, ix, x, xii, 1-10, 1-11, 2-5, 2-7, 2-8, 2-10, 3-9, 4-52, 4-53, 4-54, 4-55, 4-56, 4-57, 4-58, 

4-59, 4-78, 4-83, 4-104, 4-105, 4-141, 4-142, 4-143, 4-145, 4-146, 4-148, 4-211, 5-4 

Loss of Well Control, viii, 3-21, 3-22, 4-17, 4-23, 4-146, 4-153

Louisiana Highway 1, 4-181, 4-198

Low Relief, xii, 1-11, 2-7, 2-8, 3-9, 4-52, 4-53, 4-54, 4-57, 4-142, 4-143, 4-145, 4-146, 4-211

Macondo, 3-12, 3-21, 4-7, 4-22, 4-28, 4-29, 4-51, 4-58, 4-64, 4-66, 4-75, 4-81, 4-88, 4-91, 4-118, 4-155, 

4-200, 4-207, 4-210

Marine Mammals, x, xii, 1-4, 1-5, 1-11, 2-6, 2-7, 2-9, 4-4, 4-6, 4-92, 4-93, 4-94, 4-95, 4-96, 4-97, 4-98, 

4-99, 4-100, 4-101, 4-106, 4-108, 4-110, 4-211, 4-214, 4-215, 5-6, 5-7 

Mercury, 4-145, 4-150, 4-152, 4-155

Meteorological Conditions, 4-10, 4-19, 4-20, 4-25, 4-27, 4-105

Mitigating Measures, vii, ix, x, xi, xii, 1-8, 1-10, 1-11, 2-3, 2-5, 2-6, 2-9, 2-12, 4-5, 4-6, 4-8, 4-55, 4-62, 

4-72, 4-108, 4-127, 4-198, 4-210, 4-211, 4-218, 5-4, 5-9, 5-10

NEPA, vii, viii, ix, 1-3, 1-4, 1-5, 1-7, 1-8, 1-9, 1-11, 2-3, 2-4, 2-5, 2-7, 4-3, 4-4, 4-5, 4-6, 4-7, 4-8, 4-15, 

4-46, 4-51, 4-52, 4-59, 4-67, 4-92, 4-99, 4-102, 4-111, 4-113, 4-116, 4-118, 4-122, 4-135, 4-136, 4-141, 

4-149, 4-171, 4-176, 4-183, 4-184, 4-195, 4-197, 4-209, 5-3, 5-4, 5-5, 5-6, 5-9 

Noise, xiv, 3-6, 3-11, 4-92, 4-93, 4-94, 4-95, 4-97, 4-98, 4-99, 4-102, 4-103, 4-106, 4-107, 4-110, 4-111, 

4-123, 4-124, 4-127, 4-131, 4-134, 4-149, 4-151, 4-152, 4-154, 4-158, 4-161, 4-162, 4-164, 4-184, 

4-202, 4-208, 4-210, 4-215

Nonchemosynthetic Deepwater Benthic Communities, xii, 2-8, 4-78, 4-79, 4-141, 4-144, 4-146, 4-211

Offshore Spills, xiii, 3-12, 3-17, 3-18, 3-19, 3-20, 4-31, 4-32, 4-33, 4-36, 4-40, 4-46, 4-48, 4-49, 4-50, 

4-130, 4-138, 4-145, 4-151, 4-153

Oil Spills, viii, x, xi, xiii, xiv, 1-6, 1-7, 2-8, 2-9, 3-11, 3-12, 3-15, 3-16, 3-17, 3-18, 3-19, 3-20, 3-22, 3-38, 

4-3, 4-4, 4-5, 4-6, 4-7, 4-9, 4-13, 4-14, 4-15, 4-16, 4-17, 4-19, 4-21, 4-22, 4-23, 4-24, 4-28, 4-29, 4-30, 

4-31, 4-32, 4-33, 4-34, 4-36, 4-37, 4-38, 4-39, 4-40, 4-43, 4-46, 4-47, 4-48, 4-49, 4-50, 4-51, 4-52, 

4-53, 4-54, 4-55, 4-56, 4-57, 4-58, 4-59, 4-60, 4-61, 4-62, 4-63, 4-64, 4-65, 4-66, 4-67, 4-70, 4-71, 

4-72, 4-73, 4-75, 4-76, 4-77, 4-79, 4-81, 4-82, 4-83, 4-85, 4-86, 4-87, 4-88, 4-89, 4-90, 4-91, 4-92, 

4-93, 4-94, 4-96, 4-97, 4-99, 4-100, 4-101, 4-102, 4-104, 4-105, 4-110, 4-111, 4-112, 4-113, 4-114, 

4-115, 4-116, 4-117, 4-118, 4-119, 4-120, 4-121, 4-122, 4-123, 4-124, 4-126, 4-130, 4-134, 4-136, 

4-138, 4-139, 4-140, 4-141, 4-143, 4-145, 4-146, 4-148, 4-149, 4-150, 4-151, 4-153, 4-155, 4-156, 

4-157, 4-158, 4-159, 4-160, 4-161, 4-163, 4-164, 4-165, 4-166, 4-168, 4-170, 4-171, 4-172, 4-173, 

4-174, 4-175, 4-176, 4-177, 4-178, 4-179, 4-182, 4-187, 4-188, 4-189, 4-190, 4-191, 4-192, 4-193, 
Keywords-6 Central Planning Area Lease Sales 235, 241, and 247 EIS

4-194, 4-195, 4-196, 4-197, 4-199, 4-200, 4-201, 4-207, 4-208, 4-209, 4-210, 4-211, 4-214, 4-215, 

4-216, 4-217, 4-218, 5-4, 5-9 

OSRA, ix, 3-16, 3-17, 3-19, 4-130

Physical Oceanography, 3-39

Pinnacle Trend, ix, xii, 2-5, 2-7, 2-8, 2-10, 4-52, 4-53, 4-54, 4-55, 4-56, 4-57, 4-58, 4-142, 4-143, 4-146, 

4-211

Pipelines, x, xi, xiii, 2-6, 3-9, 3-11, 3-12, 3-13, 3-16, 3-17, 3-18, 3-20, 3-22, 3-24, 3-25, 3-26, 3-29, 3-35, 

4-14, 4-15, 4-17, 4-23, 4-31, 4-32, 4-33, 4-36, 4-38, 4-39, 4-40, 4-41, 4-42, 4-44, 4-46, 4-48, 4-49, 

4-52, 4-60, 4-80, 4-84, 4-104, 4-115, 4-117, 4-128, 4-138, 4-141, 4-144, 4-157, 4-168, 4-169, 4-170, 

4-174, 4-175, 4-178, 4-179, 4-180, 4-209, 4-215, 4-216

Port Fourchon, xv, 3-20, 4-163, 4-180, 4-181, 4-186, 4-198

Produced Waters, 3-10, 4-42, 4-53, 4-57, 4-58, 4-65, 4-66, 4-69, 4-72, 4-76, 4-78, 4-84, 4-86, 4-87, 4-90, 

4-96, 4-123, 4-125, 4-141, 4-145, 4-153, 4-154, 4-158, 4-214

Public Services, x

Recreational Fishing, x, xiv, 2-7, 2-9, 4-8, 4-43, 4-56, 4-62, 4-89, 4-97, 4-108, 4-143, 4-151, 4-154, 

4-157, 4-158, 4-159, 4-160, 4-161, 4-163, 4-164, 4-211, 4-215, 4-218

Recreational Resources, x, xiv, 2-7, 2-9, 4-8, 4-161, 4-162, 4-163, 4-164, 4-165, 4-211

Resource Estimates, 3-3, 3-4 

Sargassum, x, xii, 2-7, 2-8, 4-67, 4-68, 4-69, 4-70, 4-71, 4-103, 4-104, 4-141, 4-143, 4-146, 4-211, 4-214

Sea Turtles, x, xii, 1-11, 2-6, 2-7, 2-9, 4-6, 4-70, 4-95, 4-102, 4-103, 4-104, 4-105, 4-106, 4-107, 4-108, 

4-109, 4-110, 4-111, 4-112, 4-113, 4-208, 4-211

Seagrass Communities, x, xi, 2-7, 2-8, 4-39, 4-47, 4-48, 4-49, 4-103, 4-141, 4-143, 4-144, 4-146, 4-211

Service Base, 3-13, 4-46, 4-115, 4-145, 4-179, 4-180, 4-181, 4-186

Site Clearance, xiv, 1-11, 2-6, 4-170

Soft Bottoms, x, xii, 2-7, 2-8, 4-6, 4-74, 4-76, 4-81, 4-83, 4-84, 4-85, 4-86, 4-87, 4-88, 4-89, 4-90, 4-92, 

4-141, 4-144, 4-146, 4-211

Spill Response, 3-19, 3-20

Spills, viii, xii, xiii, xiv, xv, 1-11, 2-12, 3-11, 3-12, 3-15, 3-16, 3-17, 3-18, 3-19, 3-21, 3-22, 3-23, 4-4, 

4-7, 4-13, 4-14, 4-15, 4-17, 4-19, 4-21, 4-23, 4-25, 4-28, 4-30, 4-31, 4-32, 4-33, 4-34, 4-35, 4-36, 4-38, 

4-40, 4-42, 4-43, 4-46, 4-48, 4-49, 4-50, 4-53, 4-55, 4-56, 4-58, 4-60, 4-61, 4-62, 4-63, 4-65, 4-66, 

4-68, 4-70, 4-72, 4-74, 4-75, 4-76, 4-78, 4-83, 4-90, 4-93, 4-96, 4-99, 4-100, 4-103, 4-104, 4-105, 

4-111, 4-113, 4-114, 4-115, 4-116, 4-117, 4-118, 4-119, 4-120, 4-122, 4-123, 4-124, 4-126, 4-130, 

4-135, 4-138, 4-139, 4-142, 4-143, 4-145, 4-146, 4-151, 4-153, 4-154, 4-155, 4-157, 4-158, 4-159, 

4-160, 4-161, 4-163, 4-166, 4-168, 4-172, 4-174, 4-176, 4-178, 4-179, 4-182, 4-189, 4-190, 4-192, 

4-193, 4-195, 4-197, 4-199, 4-201, 4-206, 4-209, 4-211, 4-212, 4-214, 4-215

Submerged Vegetation, 4-47, 4-48, 4-49, 4-50, 4-51, 4-52

Synthetic-Based Drilling Fluids, 3-23

Topographic Features, ix, x, xii, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-11, 2-12, 3-9, 4-6, 4-59, 4-60, 4-61, 4-62, 

4-63, 4-64, 4-65, 4-66, 4-67, 4-91, 4-141, 4-142, 4-143, 4-144, 4-145, 4-146, 4-147, 4-210, 4-211, 

4-212

Tourism, x, 4-31, 4-32, 4-35, 4-36, 4-44, 4-46, 4-117, 4-159, 4-160, 4-161, 4-162, 4-163, 4-164, 4-165, 

4-193, 4-202, 4-203, 4-216, 4-218, 5-6 

Trash, x, xiii, 3-14, 4-15, 4-96, 4-99, 4-103, 4-104, 4-110, 4-114, 4-115, 4-116, 4-118, 4-119, 4-120, 

4-121, 4-122, 4-124, 4-128, 4-130, 4-134, 4-162, 4-165, 4-198, 4-209, 4-215
Keyword Index Keywords-7 

Waste Disposal, 3-13, 4-39, 4-42, 4-43, 4-130, 4-178, 4-179, 4-182, 4-186, 4-188, 4-199

Wastes, xi, 2-7, 3-10, 3-14, 3-26, 4-18, 4-21, 4-24, 4-25, 4-27, 4-38, 4-76, 4-108, 4-145, 4-150, 4-188

Water Quality, x, xi, xii, 2-7, 2-8, 4-6, 4-17, 4-18, 4-19, 4-20, 4-21, 4-22, 4-23, 4-24, 4-25, 4-26, 4-27, 

4-28, 4-29, 4-58, 4-64, 4-66, 4-68, 4-69, 4-71, 4-92, 4-102, 4-103, 4-104, 4-107, 4-124, 4-125, 4-130, 

4-137, 4-139, 4-140, 4-141, 4-142, 4-143, 4-144, 4-145, 4-146, 4-147, 4-153, 4-164, 4-211, 4-214, 

4-215, 4-218, 5-4 

Wetlands, x, xi, 1-6, 2-6, 2-7, 2-8, 2-9, 3-21, 3-33, 3-34, 3-35, 3-37, 4-5, 4-6, 4-32, 4-34, 4-37, 4-38, 4-39, 

4-40, 4-41, 4-42, 4-43, 4-44, 4-45, 4-46, 4-47, 4-51, 4-115, 4-116, 4-117, 4-126, 4-127, 4-128, 4-130, 

4-131, 4-133, 4-136, 4-141, 4-143, 4-144, 4-146, 4-147, 4-154, 4-160, 4-163, 4-180, 4-181, 4-184, 

4-185, 4-186, 4-196, 4-200, 4-202, 4-204, 4-205, 4-209, 4-211, 4-214, 4-216, 4-218

The Department of the Interior Mission

As the Nation’s principal conservation agency, the Department of the Interior 

has responsibility for most of our nationally owned public lands and natural 

resources. This includes fostering the sound use of our land and water 

resources; protecting our fish, wildlife, and biological diversity; preserving the 

environmental and cultural values of our national parks and historical places; 

and providing for the enjoyment of life through outdoor recreation. The 

Department assesses our energy and mineral resources and works to ensure 

that their development is in the best interests of all our people by encouraging 

stewardship and citizen participation in their care. The Department also has a 

major responsibility for American Indian reservation communities and for 

people who live in island communities. 

The Bureau of Ocean Energy Management Mission 

The Bureau of Ocean Energy Management (BOEM) promotes energy 

independence, environmental protection, and economic development through 

responsible, science-based management of offshore conventional and 

renewable energy.