6) Response

ExxonMobil has contracted with Marine Spill Response Corporation (MSRC) and Clean Gulf Associates (CGA) as primary Oil Spill Removal Organizations. Contact information for both OSROs can be found in Figure 7-2 of the oil spill response plan. Upon notification of the spill, ExxonMobil would request mobilization from the resources identified in the Appendix E of the oil spill response plan.

An Adios 2 model was run on a similar product. The results indicate 19% of the product would be evaporated or naturally dispersed within 24 hours, leaving approximately 142,475 bbls on the water.

Sample Rescouce Response Status Boards above outline skimming equipment as well as temporary storage equipment to be considered in order to cope with an initial spill of 175,895 bbls. The list estimates individual times needed for procurement, load out, travel time to the site and deployment.

Upon notification of the spill, ExxonMobil would request a partial or full mobilization of resources, including, but not limited to, MSRC and/or CGA skimming vessels and dispersant aircraft available from Airborne Support, Inc. (ASI) through memberships with MSRC and CGA. Aerial dispersant aircraft available from CCA may also be called depending on oil spill severity. The Qualified Individual, Person in Charge, Incident Commander or designee may contact other service companies if the Unified Command deems such services necessary to the response effort.

Simultaneous operations (SIMOPS) may involve different companies working in close proximity on identical and/or different tactical objectives. SIMOPS may include but are not lmited to subsea operations, surface operations or a combination of both. These operations must be well planned and coordinated. SIMOPS will be evaluated daily and coordinated based on the response efforts needs, as well as, additional criteria (e.g. meteorological conditions, sea state, etc.). Regular communications will be established and maintained during all SIMOPS activities.

SIMOPS activities may include but are not limited to the following:

 Dispersant Application (Aerial and/or Vessel), if approved.

 In

- situ Burning

 Mechanical Recovery

 Nearshore / Shoreline Response

 Source Control / Subsea OperationsOffshore Response

Primary offshore response would involve mechanical recovery. Offshore response strategies may include attempting to skim utilizing an MSRC Responder Vessel, Oil Spill Response Barges (OSRBs), Vessel of Opportunity (VOOs), Boats, and Fast Response Units. Other technologies (like GPS-based vessel tracking systems) may be used to facilitate coordination of marine resources. This equipment may be facilitated by air-based spotters that can guide these systems to oil concentrations. During night-time operations, skimming activities could be facilitated through the use of alternative spill surveillance technologies (such as infrared [IR] and X-band radio systems) to guide skimming vessels to sufficient concentrations of oil. The specific technologies used will be chosen based on availability, suitability, OSRO recommendations, and other considerations that are specific to the situation.

Offshore response strategies include, but are not limited, to the following:

• Mobilize mechanical recovery resources, including vessels (both OSRVs and VOOs), barges, ocean boom, skimming equipment, and spotter/surveillance aircraft. Begin deploying mechanical recovery resources as close to the source as possible to contain and collect concentrated oil in a timely, and effective m anner. Radio communications will be established between spotter aircraft and other surveillance systems (including AIS) with skimming vessels and barges to direct
vessels to locations of concentrated oil to ensure maximum effectiveness and efficiency of mechanical recovery equipment.

• Mobilize dispersant resources to pre

- approved and approved locations for both aerial and boat application, in areas where oil cannot be mechanically recovered. Subsea dispersant application equipment may be mobilized at the discretion of the RRT, and requires approval from the RRT. If approved, subsea dispersant application with be in accordance with RRT 6 guidelines.

• Mobilize in

- situ burn resources outside the vicinity of the source to collect andburn oil in heavily concentrated locations. Fire boom will be deployed in a Uconfiguration

• Mobilize offshore vessels equipped with remote sensing technologies (radar, infrared camera) to aid in night time operations and slick tracking. Remote sensing technologies assist skimming vessels in identifying thick areas of oil to enhance encounter rate and Estimated Derated Receovery Capacity (EDRC).

• Maintain an effective and well coordinated response effort for the length of time to control the source of the discharge, which may involve drilling a relief well, and up to the point when the Federal On-Scene Coordinator determines the response effort complete.

Mechanical oil spill response uses physical barriers (boom) and mechanical devices (skimmers) to
redirect and remove oil from the surface of the water.Mechanical cleanup strategies include, but are not limited, to the following:

• Skimming systems will deploy boom in a variety of different configurations. Generally, boom will be deployed in a J-configuration in a single skimming unit, which requires only one assist vessel to attend the boom. These single skimming units will locate heavily concentrated oil, with assistance from spotters and remote sensing technologies, to ensure enhanced encounter rate and effective recovery. Boom will be deployed in a U-configuration when skimming vessels or barges have access to two assist vessels. This configuration maximizes the swath width and containment capacity. Boom may be deployed in a U-configuration with an open apex to funnel oil to awaiting skimming vessels.

• Vessels of opportunity (VOO) equipped with skimming systems will be deployed to locations of recoverable oil. For locations with light oil that cannot be recovered mechanically, vessels of opportunity will be equipped with sorbent materials to recover this light oil.

• In order to increase encounter rate, slick containment systems will be directed to locations of heavily concentrated oil from spotter aircraft and vessels with remote sensing technology. Once the oil has been contained within the booms, the oil is dumped into the path of a skimming vessel. Boom also may be configured into a U-configuration with an open apex to funnel oil to awaiting skimming vessels.

• Oil that escapes the ab ove assets and moves shoreward will be collected by vessels of opportunity that deploy sorbent boom, collection nets or other types of equipment that absorbs surface oil. These assets will be deployed as task forces that can rapidly respond to light oil.

Current proven and available sensing technology for tracking oil at night includes hand held, boat mounted and aircraft mounted infrared sensing. ExxonMobil understands that multiple new oil sensing technologies (radar, satellite imagery, fluorometry, etc.) are being reviewed and developed by the industry and as they become more mature, proven and available to the industry, ExxonMobil will work with OSROs to include these improvements in our response capability. These and any other new oil sensing technologies that become available will be deployed with the purpose of improving the ability of keeping deployed oil skimming platforms in the most highly concentrated areas of spilled oil and may be used to potentially improve the capabilities to skim beyond traditional daylight hours. However the latter capability can only be implemented taking all aspects of safe operations in account and ensuring that there is no additional risk to human life.Depending on proximity to shore and water depth, dispersants from aerial and vessel applications may be viable response options and will require the appropriate approvals as outlined in Section 18, Dispersant Use Plan. Aerial application will consist of 3 to 4 sorties from ASI’s three DC-3’s and one DC-4. In addition, spotter aircraft could be activated along with the aerial dispersant aircraft to assist in a more precise dispersant application. Assuming a 1:20 application rate, 90% effectiveness, and 3-4 sorties per day, the ASI aerial systems could disperse approximately 5,658 to 7,543 barrels of oil per day. Additionally, subsea dispersant application and boat spray application are other methods for applying dispersants. Subsea dispersant application requires approval from the appropriate RRT.

A list of available dispersant stockpiles is located in Section 18, Dispersant Use Plan. Additional dispersant supplies are available and may be acquired from other sources through industry agreements at the direction of the FOSC and appropriate RRT. Priorities for dispersant use and rationing of existing supplies will be determined on an incident specific basis to allow for maximum effectiveness of dispersants. Dispersant use will be dictated by approval, safety, weather, and sea states before application and coordinated with Unified Command. In addition, ExxonMobil will assess the situation and can make notification within 48 hours of the initial spill to begin ramping up dispersant production through Nalco, as discussed in Section 18, Dispersant Use Plan.

ExxonMobil has contracted with Marine Well Containment Company for a subsea dispersant package. Subsea dispersant application has been found to be highly effective at reducing the amount of oil reaching the surface; however, approval is required from the appropriate Regional Response Team (RRT) prior to use. Additional data collection, laboratory tests and field tests will help in facilitating the optimal application rate and effectiveness numbers. For planning purposes, ExxonMobil assumes a 1:100 application rate, at 90% effectiveness (based on accepted industry dispersant effectiveness standards), and a system flow rate of 8-11 gallons per minute (approximately 11,500 to 16,000 gallons of dispersant per day). Using these assumptions, the system has the potential to disperse approximately 24,500 to 34,000 barrels of oil per day.

Dispersant use will be dictated by approval, safety, weather, and sea states before application and coordinated with Unified Command. In addition, ExxonMobil will assess the situation and can make notification within 48 hours of the initial spill to begin ramping up dispersant production through
Nalco.

All dispersant applications will be in compliance with RRT 6 guidelines.Open-water in-situ burning (ISB) also may be used as a response strategy, depending on the circumstances of the release. ISB services may be provided by the primary OSRO contractors. If appropriate conditions exist and approvals are granted, one or multiple ISB task forces could be deployed offshore. Task forces typically consist of two to four fire teams, each with two vessels capable of towing fire boom, guide boom or tow line with either a handheld or aerially-deployed oil ignition system. At least one support/safety boat would be present during active burning operations to provide logistics, safety and monitoring support. Depending upon a number of factors, up to 4 burns per 12-hour day could be completed per ISB fire team. Most fire boom systems can be used for up to 8 burns before being replaced. Fire intensity and weather will be the main determining factors for actual burns per system. Although the actual amount of oil that will be removed per burn is dependent on many factors, recent data suggests that a typical burn might eliminate approximately 750 barrels. For planning purposes and based on the above assumptions, a single task force of four fire teams with the appropriate weather and safety conditions could complete four burns per day and remove up to ~12,000 bbls/day. In-situ burning nearshore and along shorelines may be a possible option based on several conditions and with appropriate approvals, as outlined in Section 19, In-situ Burn Plan. In-situ burning along certain types of shorelines may be used to minimize physical damage where access is limited or if it is determined that mechanical/manual removal may cause a substantial negative impact on the environment. All safety considerations will be evaluated. Additional information on ISB is presented in Section 19, In-situ Burn Plan. In addition, ExxonMobil will assess the situation and can make notification within 48 hours of the initial spill to begin ramping up fire boom production through contracted OSRO(s) as discussed in Section 19, In-situ Burn Plan.

Slick (fresh oil) containment systems may be deployed (provided it is safe to do so) in thick, fresh oil to minimize further spreading of oil on the water’s surface. These systems would typically consist of two offshore vessels (capable of trolling speeds of 0.5 knots) towing between 1,000 to 1,500 feet of offshore boom in a “U” or “V” configuration. The containment systems would allow fresh oil to be contained, concentrated and diverted to skimming systems and/or in-situ burn task forces, increasing their encounter rate and containment efficiency in order to support enhanced skimming and burning operations.

The initial response to a well blowout would be an attempt to activate the blowout preventers and close the well. The Source Control team will be stood up immediately. The primary well control provider, Marine Well Containment Company (MWCC), would be notified in the event of a blowout. The first step will be determining if the well can be capped and killed. If the well cannot be capped, the relief well(s) operations may start as soon as possible.

Subsea containment resources would be mobilized in the event of an uncontrolled well blowout. Subsea containment incorporates simultaneous operations to cap or contain the flow of oil within the well, contain the oil outside of the well and collect at surface facilities or vessels and chemically disperse the oil at the well head. MWCC has been contracted to supply the subsea dispersant applications.Source control acti vities include, but are not limited, to the following:

• Notifications to regulatory authorities, MWCC, and support contractors regarding well control incident

• Site assessment, initial response, and well monitoring

• Notification and activation of any equipment and contract services outside of MWCC will be initiated by ExxonMobil (e.g. shuttle tankers, helicopters, etc.)

• Notification, as needed, to members of MWCC to assist ExxonMobil’s Source Control Group during source control operations

• Debris Removal and Lower Marine Riser Package (LMRP) Recovery Considerations, if applicable

• Coordination of ROVs, support vessels, intervention vessels, subsea dispersant equipment, debris removal tools, umbilical, chemical delivery, pumping services, and other equipment for WCD scenarios

• Run Intervention Riser System

• Well Capping and Shut

- in Operation Activities

In the unlikely event of a well control issue, ExxonMobil, as a member of the Marine Well Containment Company (MWCC), has access to an Interim Containment Response System (ICRS) that can be rapidly mobilized through the MWCC. The ICRS consists of equipment to contain and capture a hydrocarbon release from a damaged deepwater well. The primary component of the ICRS for well control is the capping stack. Additional components include a subsea dispersant application system, hydrate inhibition system, and a “top hat” (designed to recover discharged oil). MWCC will provide containment response support through a combination of equipment and services (owned, via mutual aid commitments, or through agreements with MWCC). Under direction of ExxonMobil, MWCC will participate with the response team to support direction of MWCC equipment and tools.

For additional detailed information on these systems, their components, and deployment times, refer to the current Marine Well Containment Company Interim Containment Response System Functional Specifications USWC-ED-BPFEP-000001 provided to BSSE by MWCC. Information on how these systems will be deployed to respond to a specific well, can be found in the NTL 2010-N10 information submitted as a supplement to the individual “Application for Permit to Drill”. Refer to Section 6 for further details regarding Source Control.

Nearshore and Shoreline Protection

Potential shoreline impact would depend upon existing environmental conditions. Nearshore response may include the deployment of shoreline boom on beach areas, or protection and sorbent boom on vegetated areas. Sorbent boom is a readily available resource and can be acquired as needed. MSRC and CGA have resources which can be deployed for a shoreline cleanup effort (equipment locations are depicted on the MSRC and CGA Equipment Location map), as well as the contractor Shoreline Protection & Wildlife Support status board in this section. Strategies would be based upon surveillance and real time trajectories provided by The Response Group that depict areas of potential impact given actual sea and weather conditions.

Strategies from the Area Contingency Plan, The Response Group and Unified Command would be consulted to ensure that environmental and special economic resources would be correctly identified and prioritized to ensure optimal protection. The Response Group’s Shoreline Response Guides depict the protection response modes applicable for oil spill clean-up operations. Each response mode is schematically represented to show optimum deployment and operation of the equipment in areas of environmental concern. Supervisory personnel have the option to modify the deployment and operation of equipment, allowing for a more effective response to site-specific circumstances. (For more information on resource identification and protection methods, see Section 11, Resource Identification. See Section 12, Strategic Response Planning for additional information on Offshore and Nearshore / Shoreline response tactics. For more information on available OSRO equipment for shoreline protection, see Appendix E, Response Equipment. A time frame for the mobilization of equipment is outlined in Section 14, Mobilization & Deployment Methods, based on equipment locations).If wildlife is threatened due to a spill, MSRC and CGA have resources available to ExxonMobil. These

resources can be utilized to protect and rehabilitate wildlife. Additional wildlife equipment may also be tiered in from OSR. See Appendix E, Response Equipment, for details on the available resources, and Section 17, Wildlife Rehabilitation Procedures, for further details on the protection and rehabilitation of affected wildlife and contacts for available wildlife protection and rehabilitation providers.

### SECTION 10: ENVIRONMENTAL MONITORING INFORMATION

10.1 Monitoring Systems

A rig based Acoustic Doppler Current Profiler (ADCP) is used to continuously monitor the current beneath the Rig. Metocean conditions such as sea states, wind speed, ocean currents, etc. will also be continuously monitored. ExxonMobil will comply with NTL 2009-G02.



### 10.2 Incidental Takes

No incidental takes are anticipated. ExxonMobil imp lements the mitigation measures and monitors for incidental takes of protected species according to the following notices to lessees and operators from the BOEM/BSEE:

NTL 2012-BSEE-G01 “Marine Trash and Debris Awareness and Elimination” NTL 2012-Joint-G01 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting” NTL 2012-Joint-G02 “Implementation of Seismic Survey Mitigation measures & Protected Species Observer Program”



### 10.3 Flower Garden Banks National Marine Sanctuary

The operations proposed in this EP will not be conducted within the Protective Zones of the Flower Garden Banks and
Stetson Bank.

### SECTION 11: LEASE STIPULATIONS INFORMATION

Lease OCS-G 33364 is not part of a Biological Sensitive Area, known Chemosynthetic Area, or Shipping Fairway. It is not on the list of areas that the BOEM has identified as having a high probability for archeological resources.

♦ **S tipulation 8: Protected Species**  This Lease Stipulation assigned to Walker Ridge Block 282 is to reduce the potential taking of federally protected species (e.g., sea turtles, marine mammals, Gulf sturgeon and other listed species). See Sections 6, 10 and 12 of this EP.

♦ **Marine Protected Species** BOEM has issued Notice to Lessees NTL 2012-Joint-G02 “Implementation of Seismic Mitigation Measures and Protected Species Observer Program”, NTL 2012-Joint-G01 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting” and NTL 2012-G01 “Marine Trash and Debris Awareness and Elimination” to reference measures to minimize or avoid potential adverse impacts to protected species (sea turtles, marine mammals, gulf sturgeon, and other federally protected species). See Sections 6, 10 and 12 of this EP.

### SECTION 12: ENVIRONMENTAL MITIGATION MEASURE INFORMA TION

12.1 Impacts to Marine and Coastal Environments

The proposed action will implement mitigation measures required by laws and regulations, including all applicable Federal & State requirements concerning air emissions, discharges to water, and solid waste disposal, as well as any additional permit requirements and ExxonMobil policies. Project activities will be conducted in accordance with the Regional Oil Spill Response Plan. The EIA in Section 18 discusses impacts and mitigation measures.



### 12.2 Incidental Takes

We do not anticipate any incidental takes related to the proposed operations. ExxonMobil implements the mitigation measures and monitors for incidental takes of protected species according to the following notices to lessees and operators from BOEM/BSEE:

NTL 2012-BSEE-G01 “Marine Trash and Debris Awareness and Elimination” NTL 2012-Joint-G01 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting” NTL 2012-Joint-G02 “Implementation of Seismic Survey Mitigation measures & Protected Species Observer

Program”

### SECTION 13: RELATED FACILITIES AND OPERATIONS INFORM ATION

Information regarding Related Facilities and Operations Information, transportation systems, & produced liquid hydrocarbon transportation vessels are not included in this EP as such information is only necessary in the case of DOCDs.

### SECTION 14: SUPPORT VESSELS AND AIRCRAFT INFORMATION

14.1 General

Type Maximum Fuel Tank

Storage Capacity (Gals) Maximum No. In Area at Any Time Trip Frequency or
Duration

Crew Boats 8,000 2 Twice per week

Offshore Support Vessels 120,000 3 Twice per week

Helicopter 764 1 Once per day



### 14.2 Diesel Oil Supply Vessels

Size of Fuel Supply
Vessel Capacity of Fuel

Supply Vessel Frequency of Fuel
Transfers Route Fuel Supply Vessel Will
Take

280 foot length 100,000 gals. 1 week Port Fourchon to WR 282



### 14.3 Drilling Fluids Transportation

This information is only required for Eastern Gulf of Mexico.



### 14.1 Solid and Liquid Wastes Transportation

See Table 7B.



### 14.5 Vicinity Map

See Attached.Vicinity Map

### SECTION 15: ONSHORE SUPPORT FACILITIES INFORMATION

15.1 General

Name Location Existing/New/Modified

Fourchon Port Fourchon, LA Existing

PHI Base Morgan City, LA Existing

Galveston Base Galveston, TX Existing

The proposed surface disturbances in Walker Ridge Block 282 for this plan will be located approximately 162 miles from the nearest Louisiana shoreline, and approximately 178 miles from the onshore support base. ExxonMobil will use the Port Fourchon existing dock as support base. The Fourchon facility is located on Bayou Lafourche, south of Leeville, LA approximately 3 miles from the Gulf of Mexico. The helicopter base will be the PHI base located in Morgan City, LA. The Galveston Base in Galveston, TX may be used for operations in this plan.



### 15.2 Support Base Construction or Expansion

This section does not apply to this EP as ExxonMobil does not plan to construct a new onshore support base or expand an existing one to accommodate the activities proposed in this EP.



### 15.3 Support Base Construction or Expansion Timetabl e

This section does not apply to this EP as ExxonMobil does not plan to construct a new onshore support base or expand an existing one to accommodate the activities proposed in this EP.



### 15.4 Waste Disposal

See Tables 7A and 7B.



### 15.5 Air emissions

Not required by BOEM GOM.



### 15.6 Unusual solid and liquid wastes

Not required by BOEM GOM.

### SECTION 16: SULPHUR OPERATIONS INFORMATION

Information regarding Sulphur Operations is not included in this EP as such information is only necessary in the case of

DOCDs.

### SECTION 17: COASTAL ZONE MANAGEMENT ACT (CZMA) INFOR MATION

LOUISIANA

COASTAL ZONE MANAGEMENT

CONSISTENCY CERTIFICATION

EXPLORATION PLAN Type of Plan

WALKER RIDGE BLOCK 282 (OCS-G 33364)

The proposed activities described in detail in this Plan will comply with Louisiana's State and Local Coastal Resources Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable Policies.

We have considered all of Louisiana's Enforceable Policies in making this certification of consistency.

EXXON MOBIL CORPORATION

Operator

_____________________________________________

Bryan L. Chapman Certifying Official

04/08/2013 Date

### TEXAS

COASTAL ZONE MANAGEMENT

CONSISTENCY CERTIFICATION

EXPLORATION PLAN Type of Plan

WALKER RIDGE BLOCK 282 (OCS-G 33364)

The proposed activities described in detail in this Plan will comply with Texas State and Local Coastal Resources Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable Policies.

We have considered all of Louisiana's Enforceable Policies in making this certification of consistency.

EXXON MOBIL CORPORATION

Operator

_____________________________________________

Bryan L. Chapman Certifying Official

04/08/2013 DateCoastal Zone Management Consistency Information
For the State of Texas

In accordance with Subpart E of 15 CFR 903 “Consistency for Outer Continental Shelf (OCS) Exploration, Development and Production Activities” and as required by 15 CFR 930.58, Exxon Mobil Corporation is hereby providing the following information in support of the Environmental Impact Analysis submitted as Attachment 18 of our initial EP.

15 CFR 930.58 identifies necessary data and information to be furnished to the State agency. The information is as
follows:

(a) CONSISTENCY CERTIFICATION A Coastal Zone Consistency Certification for activities that affect the State of Texas is provided in Section 17 of the
above-mentioned EP.

OTHER INFORMATION

A detailed description of the proposed activities, coastal effects, and comprehensive information sufficient to support this Consistency Certification is presented in Section 17 of the above-mentioned EP. As per NTL 2008-G04, the following items have been identified as being required:

• A discussion of the method of disposal of wastes and discharges is provided in Section 7 of the abovementioned EP.

• Oil Spill Information is provided in Section 9 of the above-mentioned EP. All operations are covered by ExxonMobil’s Regional Oil Spill Response Plan, which has been updated (pending approval) by BSEE. The Plan is available upon request.

Following is an evaluation that includes findings relating the coastal effects of the proposed activities and associated facilities to the relevant enforceable policies of the Texas’ Coastal Management Program (TCMP), Title 31, Part 16, Chapter 501, Subchapter B **:**

(Category 2) Construction, Operation & Maintenance of Oil & Gas Exploration & Production
Facilities No operations are proposed in or near any critical areas. The proposed activities are of exploration in nature, so no facility construction is proposed. The proposed activities are located approximately 292 miles from the Texas shoreline; therefore we expect no adverse impacts to CNRAs or beach access and use rights of the public. All activities shall be conducted in a manner that minimizes significant impacts to coastal resources. No adverse effects to Texas’ coastal area are expected in association with the proposed activities.

(Category 3) Discharges of Wastewater and Disposal of Waste from Oil and Gas Exploration and Production Activities No discharge of wastewater or disposal of waste from the proposed activities will occur in the Texas’ coastal zone area; therefore no impact to Texas’ coastal waters is expected.

(Category 4) Construction and Operation of Solid Waste Treatment, Storage, and Disposal
Facilities No construction of solid waste facilities or expansion of existing facilities in the coastal zone are proposed in the attached plan, therefore, no adverse effects on any features of Texas’ coastal zone are expected.(Category 5)

Prevention, Response, and Remediation of Oil Spills The proposed activities will be covered under an approved Regional Oil Spill Response Plan. The plan is in place, practiced, and updated as necessary. The best practical techniques shall be utilized to prevent the release of pollutants or toxic substances into the environment. All involved vessels and facilities are designed to be capable of prompt response and adequate removal of accidental discharges of oil. In addition, the proposed activities are 292 miles from shore; therefore no damages to natural resources are expected as the result of an unauthorized discharge of oil into
coastal waters.

(Category 6) Discharge of Municipal and Industrial Waste Water to Coastal Waters No discharges from the proposed activities will occur in coastal waters. The proposed activities are 292 miles from Texas shore; therefore there will be no effect on coastal waters.

(Category 8) Development in Critical Areas None of the proposed activities will occur in a critical area; therefore no effects to Texas’ coastal zone are expected. The activity will not jeopardize the continued existence of species listed as endangered or threatened, and
will not result in likelihood of the destruction or adverse modification of a habitat determined to be a critical habitat under the Endangered Species Act. The activity will not cause or contribute to violation of any applicable surface water quality standards. The activity will not violate any requirement imposed to protect a marine sanctuary.

(Category 9) Construction of Waterfront Facilities and Other Structures on Submerged lands No waterfront facilities or other structures are proposed on submerged lands in the Texas coastal zone, therefore the proposed activities are not expected to have any adverse impacts on submerged lands.

(Category 10) Dredging and Dredged Material Disposal and Placement No dredging or disposal/placement of dredged material is proposed, therefore no adverse effects to coastal waters, submerged lands, critical areas, coastal shore areas, or Gulf beaches are expected.

(Category 11) Construction in the Beach / Dune System The proposed activities do not include any construction projects in critical dune areas or areas adjacent to or on Gulf beaches, therefore, no impact to Texas’ beach or dune systems are expected.

(Category 15)
Alteration of Coastal Historic Areas The proposed activities do not include any alteration or disturbance of a coastal historic area; therefore, no impacts to are expected to adversely affect any historical, architectural, or archaeological site in Texas’ coastal zone.

(Category 16) Transportation The proposed activities do not include any transportation construction projects within the coastal zone; therefore, no impacts to Texas’ coastal zone are expected.(Category 17)

Emission of Air Pollutants The proposed activities shall be carried out in conformance with applicable air quality laws, standards, and regulations. Emissions from the proposed activities are not expected to have significant impacts on onshore air quality because of the prevailing atmospheric conditions, emission heights, emission rates, and the distance of these emissions from the coastline. The proposed activities will occur approximately 292 miles from the Texas shore and will be within the exemption limits set by BOEM, therefore, no impacts to Texas’ coastal zone is expected.

(Category 18) Appropriations of Water The proposed activities do not include the impoundment or diversion of state water, therefore, no impacts to Texas’ coastal zone is expected.

(Category 20) Marine Fishery Management The proposed activities are located approximately 292 miles from Texas shore and are not expected to have any effect on marine fishery management or fishery migratory patterns within waters in the coastal zone of Texas.

(Category 22)
Administrative Policies

The necessary information for applicable agencies to make an informed decision on the proposed activities has been provided

In conclusion, all activities shall be consistent with Texas’ coastal management program and shall comply with all relevant rules and regulations. No activities are planned within any critical areas. Activities will be carried out avoiding unnecessary conflicts with other uses of the vicinity.

### SECTION 18 - ENVIRONMENTAL IMPACT ANALYSIS (EIA)



# Environmental Impact Analysis

INITIAL EXPLORATION PLAN Walker Ridge Block 282 (OCS-G 33364)

Offshore Louisiana

April 2013

Prepared for:

ExxonMobil Corporation

P.O. Box 4368 Houston, Texas 77210-4358 Telephone: (281) 654-1941

Prepared by:

CSA International, Inc.

8502 SW Kansas Avenue Stuart, Florida 34997 Telephone: (772) 219-3000

# Acronyms and Abbreviations

ADIOS2 Automated Data Inquiry for Oil Spills 2
bbl barrel BOEM Bureau of Ocean Energy Management BOEMRE Bureau of Ocean Energy Management,

Regulation and Enforcement BOP blowout preventer
B.P. Before Present BSEE Bureau of Safety and Environmental

Enforcement

CH 4 methane
CO carbon monoxide

CO 2 carbon dioxide CFR Code of Federal Regulations
CGA Clean Gulf Associates DP dynamic positioning EP Exploration Plan
EEZ Exclusive Economic Zone
EFH Essential Fish Habitat EIA Environmental Impact Analysis EIS Environmental Impact Statement ESA Endangered Species Act FAD fish-attracting device

FR **Federal Register** GPS global positioning system GMFMC Gulf of Mexico Fishery Management

Council

H 2 S hydrogen sulfide
HAPC Habitat Area of Particular Concern HOSS high-volume open sea skimmer IPF impact-producing factor
MARPOL International Convention for the

Prevention of Pollution from Ships MMC Marine Mammal Commission
MMPA Marine Mammal Protection Act MMS Minerals Management Service MSRC Marine Spill Response Corporation NAAQS National Ambient Air Quality

Standards
NMFS National Marine Fisheries Service NOAA National Oceanic and Atmospheric

Administration

NO x nitrogen oxides NPDES National Pollutant Discharge

Elimination System NRDA Natural Resource Damage Assessment NTL Notice to Lessees and Operators NWR National Wildlife Refuge
OBM oil-based mud
OCS Outer Continental Shelf OSRA Oil Spill Risk Analysis OSRP Oil Spill Response Plan PAH polycyclic aromatic hydrocarbon PM particulate matter SBM synthetic-based mud
SHL surface hole location

SO x sulfur oxides SWSS Sperm Whale Seismic Study
USCG U.S. Coast Guard USEPA U.S. Environmental Protection Agency
USFWS U.S. Fish and Wildlife Service VOC volatile organic compound WCD worst case discharge WR Walker Ridge

# Introduction

ExxonMobil Corporation (ExxonMobil) is submitting an Initial Exploration Plan (EP) for Walker Ridge (WR) Block 282 (WR 282). The EP is for one exploratory, Well “A,” in WR 282. This Environmental Impact Analysis (EIA) provides information on the exploratory well based on the surface hole location (SHL).

The lease area is 261 km (162 miles) south-southwest of the nearest shoreline and 287 km (178 miles) from the onshore support base and helicopter base at Port Fourchon, Louisiana ( Figure 1 ). Water depth at the wellsite is approximately 1,937 m (6,354 ft). The drilling rig will be the **Transocean Deepwater Champion**  or a similar dynamic positioning (DP) drillship. This EIA was prepared for submittal to the Bureau of Ocean Energy Management (BOEM) in accordance with applicable regulations, including 30 Code of Federal Regulations (CFR) 550.212(o) and 550.227. The EIA is a project- and site-specific analysis of ExxonMobil’s planned activities under this EP and complies with guidance provided in existing Notices to Lessees and Operators (NTLs) issued by the former Minerals Management Service (MMS) and the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), including NTL 2008-G04. Potential impacts have been analyzed at a broader level in Programmatic Environmental Impact Statements (EISs) for the Outer Continental Shelf (OCS) Oil and Gas Leasing Program (MMS, 2007a; BOEM, 2012d) and in multi-lease-sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b; BOEM, 2012b). The analyses from these documents are incorporated here by reference.

Statistics from offshore drilling in the U.S. Gulf of Mexico provide a reasonable basis for evaluating oil spill risk during exploratory drilling. According to Holand (1997), the average frequency of a loss of well control incident or "blowout" during exploratory drilling in the U.S. Gulf of Mexico is 0.00593 blowouts per well drilled, or one blowout per 169 exploration wells drilled. Similarly, the MMS Safety and Environmental Management Program blowout incident rate for 1996 to 1999 was approximately five blowouts per 1,000 well starts, or one blowout per 200 well starts (MMS, 2000). More recently, in its Final Supplemental EIS for the Central Gulf of Mexico Planning Area, BOEM confirmed that "significant changes to the spill rates for the entire OCS are not anticipated" (BOEM, 2012b).

Historically, most blowouts have not resulted in oil spills. Of 151 well blowouts in the Gulf of Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills, with a total combined volume of 1,000 barrels (bbl) of crude oil and condensate released (MMS, 2000). Between 1964 and 1999, almost all offshore spills (94%) from drilling and production-related operations on the OCS were ≤1 bbl in size (Anderson and LaBelle, 2000). According to BSEE’s Final Drilling Safety Rule (75 **Federal Register** [FR] 63365) issued following the Macondo incident, the baseline risk of a catastrophic blowout is estimated to be about once every 26

years.Figure 1. Location of Walker Ridge Block 282.ExxonMobil’s Regional Oil Spill Response Plan (OSRP) was originally approved by the MMS on 7 December 2009. A revised and updated OSRP was submitted to BOEM in December 2010, July 2011, and December 2011, and pending approval. The OSRP details ExxonMobil’s plan for response to rapidly and effectively manage oil spills that may result from drilling and production operations. ExxonMobil has designed its response program based on a regional capability of response to spills ranging from small operational spills to a worst discharge (WCD) from a well blowout. ExxonMobil’s spill response program meets the response planning requirements of the relevant coastal states and applicable Federal oil spill planning regulations and also includes information regarding ExxonMobil’s regional oil spill organization and dedicated response assets, potential spill risks, and local environmental sensitivities. The OSRP describes personnel and equipment mobilization, the incident management team organization, and an overview of actions and notifications to be taken in the event of a spill. All activities planned for WR 282 are covered under this regional OSRP in accordance with 30 Code of Federal Regulations (CFR) Part 254.

This EIA is organized into Sections A through I corresponding to the information required by NTL 2008-G04. The main impact-related discussions are in Section A (Impact-Producing Factors) and
Section C (Impact Analysis). Table 1 lists and summarizes the NTLs applicable to this EIA.

Table 1. Notices to Lessees and Operators (NTLs) applicable to this Environmental Impact Analysis (EIA).

NTL Title Summary

2012-N06 Guidance to Owners and Operators

of Offshore Facilities Seaward of the Coast Line Concerning Regional Oil Spill Response Plans Provides clarification, guidance, and information for preparation of regional Oil Spill Response Plans. Recommends description of response strategy for worst case discharge (WCD) scenarios to ensure capability to respond to oil discharges is both efficient and effective.

2012-BSEE-G01 Marine Trash and Debris

Awareness and Elimination Instructs operators to exercise caution in the handling and disposal of small items and packaging materials; requires the posting of placards at prominent locations on offshore vessels and structures; and mandates a yearly marine trash and debris awareness training and certification process.

2012-JOINT-G01 Vessel Strike Avoidance and

Injured/Dead Protected Species Reporting Recommends protected species identification guides be carried on all Gulf of Mexico petroleum vessels and that vessel operators and crews maintain a vigilant watch for marine mammals. Vessels are to slow down or stop to avoid striking protected species, and operators are required to report sightings of any injured or dead protected species.

2011-JOINT-G01 Revisions to the List of OCS Blocks

Requiring Archaeological Resource Surveys and Reports Provides new information of which Outer Continental Shelf (OCS) blocks require archaeological surveys and reports and required survey line spacing in each block. This NTL
augments NTL 2005

- G07.

2010-N10 Statement of Compliance with

Applicable Regulations and
Evaluation of Information Demonstrating Adequate Spill Response and Well Containment

Resources Inform s operators using subsea blowout preventers (BOPs) or surface BOPs on floating facilities that applications for well permits must include a statement signed by an authorized company official stating that the operator will conduct all activities in compliance with all applicable regulations, including the increased safety measures regulations (75 FR 63346). Informs operators that BOEM will be evaluating whether each operator has submitted adequate information demonstrating that it has access to and can deploy containment resources to promptly respond
to a blowout or other loss of well control.

2010-N06 Information Requirements for

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

OCS Rescinds the limitations set forth in NTL 2008-G04 regarding a blowout scenario and worst case discharge scenario, and provides guidance regarding the information required in blowout scenario and worst case discharge scenario descriptions.Table 1. (Continued).

NTL Title Summary

2009-G40 Deepwater Benthic Communities Guidance for avoiding and protecting high

- density deepwater benthic communities (including chemosynthetic and deepwater coral communities) from damage caused by OCS oil and gas activities in water depths greater than 300 m (984 ft). Prescribes separation distances of 610 m (2,000 ft) from each mud and cuttings discharge location and 76 m (250 ft) from all other seafloor disturbances.

2009-G39 Biologically Sensitive Underwater

Features and Areas Guidance for avoiding and protecting biologically sensitive features and areas (i.e., topographic features, pinnacles, low relief live bottom areas, and other potentially sensitive biological features) when conducting OCS operations in water depths less than 300 m (984 ft) in the Gulf of Mexico.

2009-G06 Military Warning and Water Test

Areas Provides contact links to individual command headquarters for the military warning and water test areas in the Gulf of Mexico. Lease stipulations require lessees or designated operators to enter into an agreement with the appropriate individual military command headquarters concerning the control of electromagnetic emissions and use of boats and aircraft in the applicable warning area or water test area before commencing such traffic.

2008-G04 Information Requirements for

Exploration Plans and Development Operations Coordination

Documents Guidance on the information requirements for OCS plans, including EIA requirements and information regarding compliance with the provisions of the Endangered Species
Act and Marine Mammal Protection Act.

2005-G07 Archaeological Resource Surveys

and Reports Provides guidance on regulations regarding archaeological discoveries, specifies requirements for archaeological resource surveys and reports, and outlines options for protecting archaeological resources.

# A. Impact-Producing Factors

Table 2 is a matrix of impact-producing factors (IPFs) and potentially affected environmental resources adapted from Form BOEM-142. An "X" indicates that an IPF could reasonably be expected to affect a certain resource, and a dash (--) indicates no impact or negligible impact. Where there may be an effect, an analysis is provided in Section C . Potential IPFs for the proposed activity are listed below and briefly discussed in the following sections.

• Drilling rig presence (including noise and lights)

• Physical disturbance to the seafloor

• Air pollutant emissions

• Effluent discharges • Water intake

• Onshore waste disposal

• Marine debris

• Support vessel and helicopter traffic

• Accidents

A.1 Drilling Rig Presence (including noise and lights)

The drilling rig proposed for this EP is the **Transocean Deepwater Champion** or a similar DP drillship. DP drillships use a global positioning system (GPS), specific computer software, and sensors in conjunction with their own propellers and thrusters to maintain position. Essentially, through satellite navigation, the location of the vessel is precisely monitored and thrusters positioned at various locations about the vessel’s hull are activated to provide any required station-keeping adjustment. This allows operations at sea where mooring or anchoring is not feasible.

The drilling rig for the well proposed in this EP will be on site for an estimated 150 days. The physical presence of the drilling rig in the ocean can attract pelagic fishes and other marine life, as discussed in
Section C.5.1

.

Drilling operations produce noise that includes strong tonal components at low frequencies, and in some cases infrasonic frequencies (MMS, 2000). According to Richardson et al. (1995), more sound is generally radiated underwater from drillships during drilling operations than from semisubmersibles, but this changes with the level of activity and age of equipment on the vessel. Drilling rigs also maintain exterior lighting for navigational and aviation safety in accordance with Federal regulations. This artificial lighting may attract and directly or indirectly impact natural resources. Flaring of gas from the rig may also attract and potentially impact natural resources, particularly birds.

A.2 Physical Disturbance to the Seafloor

Drillships like the **Transocean Deepwater Champion** do not use anchors for station-keeping or stabilization during drilling operations. The DP drillship will disturb only a very small area of the seafloor around the wellbore (SHL) where the bottom template and blowout preventer (BOP) are located. Depending on the specific well configuration, this area is generally about 0.25 ha (0.62 ac) (MMS, 2007a).Table 2. Matrix of impact-producing factors and affected environmental resources. X = potential impact; dash (--) = no impact or negligible impact.Environmental ResourcesImpact-producing FactorsDrilling RigPresence (incl.noise & lights)PhysicalDisturbanceto SeafloorAirPollutantEmissionsEffluent DischargesWaterIntakeOnshore WasteDisposalMarineDebrisSupportVessel/HeloTrafficAccidentsSmallFuel SpillOil Spill(WCD)Physical/Chemical EnvironmentAir quality and greenhouse gases------X(9)----------X(6)X(6)Water quality------X--------X(6)X(6)Seafloor Habitats and BiotaSoft bottom benthiccommunities--X--X----------X(6)High-density deepwater benthic communities----(4)----(4)----------X(6)Designated topographic features----(1)----(1)------------Pinnacle trend area live bottoms----(2)----(2)------------Eastern Gulf live bottoms----(3)----(3)------------Threatened, Endangered, and Protected Species and Critical HabitatSperm whale (endangered)X(8)------------X(8)X(6,8)X(6,8)West Indian manatee (endangered)--------------X(8)--X(6,8)Endangered mysticete whales--------------------Non-endangered marine mammals (protected)X------------XX(6)X(6)Sea turtles (endangered/threatened)X(8)------------X(8)X(6,8)X(6,8)Piping Plover(threatened)------------------X(6)Whooping Crane (endangered)------------------X(6)Gulf sturgeon (threatened)------------------X(6)Smalltooth sawfish (endangered)------------------X(6)Beach mice (endangered)------------------X(6)Elkhorn coral (endangered)------------------X(6)Coastal and Marine BirdsMarine birdsX------------XX(6)X(6)Shorebirds and coastal nesting birds--------------X--X(6)Fisheries ResourcesPelagic communities and ichthyoplanktonX----XX------X(6)X(6)Essential Fish HabitatX----XX------X(6)X(6)Archaeological ResourcesShipwreck sites----(7)--------------X(6)Prehistoric archaeological sites----(7)--------------X(6)Coastal Habitats and Protected AreasBeaches------------------X(6)Wetlands and seagrass beds------------------X(6)Coastal wildlife refuges and wilderness areas------------------X(6)Socioeconomic andOther ResourcesRecreational and commercial fishingX--------------X(6)X(6)Public health and safety------------------X(6)Employment and infrastructure------------------X(6)Recreation and tourism------------------X(6)Land use------------------X(6)Other marine uses------------------X(6)WCD = worst case discharge.Table 2 Footnotes and Applicability:

**(1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, rig site, or any anchors will be on the seafloor within the following:**  **(a) 4-mi zone of the Flower Garden Banks, or the 3-mi zone of Stetson Bank; (b) 1,000-m, 1-mi, or 3-mi zone of any topographic feature (submarine bank) protected by the Topographic**  **Features Stipulation attached to an Outer Continental Shelf (OCS) lease; (c) Essential Fish Habitat (EFH) criteria of 500 ft from any no-activity zone; or**  **(d) Proximity of any submarine bank (500-ft buffer zone) with relief greater than 2 m that is not protected by the Topographic Features Stipulation attached to an OCS lease.** 

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or no-activity zone. There are no submarine banks in the block.
**(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom (Pinnacle Trend) Stipulation attached to an OCS lease.** 

• The Live Bottom (Pinnacle Trend) Stipulation is not applicable to the lease area.
**(3) Activities within any Eastern Gulf OCS block and portions of Pensacola and Destin Dome area blocks in the Central Planning Area where seafloor habitats are protected by the Live Bottom (Low-Relief) Stipulation** 
**attached to an OCS lease.**

• The Live Bottom (Low-Relief) Stipulation is not applicable to the lease area.
**(4) Activities on blocks designated by the BOEM as being in water depths 300 m or greater.**

• No impacts on high-density deepwater benthic communities are anticipated. There are no features indicative of high-density chemosynthetic communities or coral communities within 610 m (2,000 ft) of the drilling mud/cuttings discharge location.
**(5) Exploration or production activities where H 2**  **S concentrations greater than 500 ppm might be encountered.**

• Based on 30 CFR 550.215, ExxonMobil is requesting that BOEM classify the lease area as “H 2 S absent.”
**(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you determine would impact these environmental resources. If the proposed action is located a sufficient distance**  **from a resource that no impact would occur, the EIA can note that in a sentence or two.**

• Accidental hydrocarbon spills could affect the resources marked (X) in the matrix, and impacts are analyzed in Section C

. **(7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated by the BOEM as having high-probability for the occurrence of shipwrecks or prehistoric sites, including such**  **blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would**  **occur, the EIA can note that in a sentence or two.**

• No impacts on archaeological resources are expected. The lease area is not on the list of archaeology survey blocks (BOEM, 2012c) and is well beyond the 60-m depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. The geohazards and archaeological assessments indicate multiple sonar contacts in the lease area, but none are interpreted to be historic shipwrecks. A dynamic positioning drillship will be used; therefore, seafloor disturbances due to anchoring will not occur.
**(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals**
**or sea turtles or their critical habitats.**

• IPFs that may affect marine mammals, sea turtles, or their critical habitats include drilling rig presence,
support vessel and helicopter traffic, and accidents. See Section C

. **(9) Production activities that involve transportation of produced fluids to shore using shuttle tankers or barges.**

• Not applicable.A.3 Air Pollutant Emissions

Air pollutant emissions are calculated in EP Section 8 and are estimated to be insignificant. Offshore air pollutant emissions will result from operations of the drillship, as well as service vessels and helicopters. These emissions occur from internal combustion engines, most of which are driven by diesel fuel. The combustion of fuels occurs on diesel-powered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended particulate matter (PM), sulfur oxides (SO
x ), nitrogen oxides (NO
x ), volatile organic compounds (VOCs), and carbon monoxide (CO).

The Air Quality Emissions Report prepared in accordance with BOEM requirements demonstrates that the projected emissions are below exemption levels set by the applicable regulations in 30 CFR 550.218. Based on calculated emissions and the well’s location relative to shore, it can be concluded that project emissions will not significantly affect onshore air quality for any of the criteria pollutants. No further analysis or control measures are required.

A.4 Effluent Discharges

Effluent discharges are summarized in EP Appendix H. All offshore discharges will be in accordance with requirements of the National Pollutant Discharge Elimination System (NPDES) General Permit No. GMG290000 issued by the U.S. Environmental Protection Agency (USEPA). Any discharges will be in compliance with the permit terms and monitored as required by the permit.

Water-based drilling muds and cuttings will be released at the seafloor during the initial well intervals before the marine riser that allows their return to the surface is set. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Synthetic-based drilling muds (SBMs) will be collected on the rig and transported to the BHI facility in Port Fourchon, Louisiana, for processing and reuse. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit.

Other effluent discharges in accordance with the NPDES permit will include excess cement, non-contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, uncontaminated freshwater and seawater, and ballast water.

A.5 Water Intake

Seawater will be drawn from the ocean for once-through, non-contact cooling of machinery on the drillship. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmental impact from impingement and entrainment of aquatic organisms. The current NPDES General Permit No. GMG290000 does not specify requirements for existing facilities (those that started construction before 16 July 2006). The DP drillship being considered for use in this EP is a “new” facility as defined by the NPDES permit and therefore triggers the cooling water intake regulations. The drillship will be in compliance with all cooling water intake requirements of the general NPDES permit.

A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in EP Appendix H. A total of approximately 10 m 3 (360 ft 3 ) of trash will be generated over the life of this project. The trash will be transported in storage bins on a work boat to shore, where it will be moved by truck to the BFI Colonial landfill in Sorrento, Louisiana, and disposed of in accordance with applicable regulations.

A.7 Marine Debris

ExxonMobil will comply with all regulations relating to solid wastes handling and disposal, including the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex Vrequirements and USEPA and U.S. Coast Guard (USCG) regulations, as well as those of the BOEM. For example, BOEM regulations at 30 CFR 250.300(a) and (b)(6) prohibit operators from deliberately discharging containers and other similar materials (i.e., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable identification markings on equipment, tools, containers (especially drums), and other material. USEPA and USCG regulations require operators to become proactive in avoiding accidental loss of solid waste items by developing waste management plans, posting informational placards, manifesting trash sent to shore, and using special precautions such as covering outside trash bins to prevent accidental loss of solid waste. In addition to the regulations in 30 CFR 250, BSEE issued NTL 2012-BSEE-G01, which instructs operators to exercise caution in the handling and disposal of small items and packaging materials, requires the posting of placards at prominent locations on offshore vessels and structures, and mandates a yearly marine trash and debris awareness training and certification process.

A.8 Support Vessel and Helicopter Traffic

ExxonMobil will use existing shorebase facilities at Port Fourchon, Louisiana, for onshore support for vessel activities and air transportation (helicopters). The air onshore support base for helicopters will be located atthe PHI heliport facility , and the marine onshore support base for the work and crew boats will be the CPort facility. These bases are capable of providing the services necessary for the proposed activities. No new facilities or workers will be needed for the proposed activities.

The project will be supported by two crew boats and three offshore support vessels. The crew boats and offshore support vessels will each make approximately two round-trips per week. In addition, an installation supply vessel will make two trips per week to the project site. All boats typically will move to the project area via the most direct route from the shorebase.

A helicopter will make one round-trip per day between the drillship and the heliport. The helicopter will be used to transport personnel and small supplies and will normally take the most direct route of travel between the shorebase and the lease area when air traffic and weather conditions permit. Helicopters typically maintain a minimum altitude of 213 m (700 ft) while in transit offshore, 305 m (1,000 ft) over unpopulated areas or across coastlines, and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and park properties. Additional guidelines and regulations specify that helicopters maintain an altitude of 305 m (1,000 ft) within 91 m (300 ft) of marine mammals (BOEM, 2012d).

Vessel noise is one of the main contributors to overall noise in the sea (National Research Council, 2003a; Jasny et al., 2005). Offshore supply and service vessels associated with the proposed project would contribute to the overall noise environment by transmitting noise through both air and water. Vessel noise is a combination of narrow-band (tonal) and broadband sound (Richardson et al., 1995). Tones typically dominate up to about 50 Hz, whereas broadband sounds may extend to 100 kHz. The primary sources of vessel noise are propeller cavitation, propeller singing, and propulsion; other sources include auxiliary engine noise, flow noise from water dragging along the hull, and bubbles breaking in the vessel’s wake while moving through the water (Richardson et al., 1995). Propeller cavitation is usually the dominant underwater noise source. The intensity of noise from service vessels is roughly related to ship size and speed. Broadband source levels for smaller boats (a category that would include supply and other service vessels) are in the range of 150 to 170 dB re 1 μPa at 1 m (Richardson et al., 1995).

Helicopters used for offshore oil and gas operation support are a potential source of noise to the marine environment. Helicopter noise is generated from their jet turbine engines, airframe, and rotors. The dominant tones for helicopters are generally below 500 Hz (Richardson et al., 1995). Richardson et al. (1995) reported received sound pressure levels in water of 109 dB re 1 μPa from a Bell 212 helicopter flying at an altitude of 152 m (500 ft). Penetration of aircraft noise below the sea surface is greatest directly below the aircraft; at angles greater than 13 degrees from vertical, much of the sound is reflected from the sea surface and so does not penetrate into the water (Richardson et al., 1995). The duration of underwater sound from passing aircraft is much shorter in water than air; for example, a helicopterpassing at an altitude of 152 m (500 ft) that is audible in air for 4 minutes may be detectable under water for only 38 seconds at 3 m (10 ft) depth and for 11 seconds at 18 m (59 ft) depth (Richardson et al., 1995).

A.9 Accidents

A.9.1 Types of Accidents Evaluated

The analysis in this EIA focuses on two potential accidents:

• a small fuel spill, which is the most likely type of spill during OCS exploration activities; and

• the WCD for this EP, which is an oil spill resulting from an uncontrolled blowout.

The following subsections summarize assumptions about the sizes and fates of these spills, as well as ExxonMobil’s spill response plans. Impacts are analyzed in Section C

.
MMS (2007b) and BOEM (2012b) analyzed three other types of accidents: chemical spills, vessel collisions, and loss of well control. These types of accidents are discussed briefly in Section A.9.4

.

A.9.2 Small Fuel Spill

Spill Size . According to the analyses in MMS (2007b) and BOEM (2012a), the most likely type of small spill (<1,000 bbl) as a result of OCS activities is a minor diesel fuel spill. Historically, most diesel spills have been ≤1 bbl, and this size is predicted to be the most common in ongoing and future OCS activities in the Western and Central Gulf of Mexico Planning Areas. As spill size increases, the incident rate declines dramatically (MMS, 2007b; BOEMRE, 2011a; BOEM, 2012b). The median size for spills ≤1 bbl is 0.024 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl (BOEM, 2012a). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational experience suggests that the most likely cause of such a spill would be a hose rupture resulting in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate . The fate of a small fuel spill in the lease area would depend on meteorological and oceanographic conditions at the time, as well as the effectiveness of spill response activities. However, given the open ocean location of the lease area and response actions, it is expected that impacts from a small spill would be minimal (BOEMRE, 2011a; BOEM, 2012b).

The water-soluble fractions of diesel are dominated by two- and three-ringed polycyclic aromatic hydrocarbons (PAHs), which are moderately volatile (National Research Council, 2003b). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Because of its light density, diesel will not sink to the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solids loads (National Research Council, 2003b) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (National Oceanic and Atmospheric Administration [NOAA], 2006).

For purposes of this EIA, the fate of a small diesel fuel spill was estimated using NOAA’s Automated Data Inquiry for Oil Spills 2 (ADIOS2) model. This model uses the physical properties of oils in its database to predict the rate of evaporation and dispersion over time, as well as changes in the density, viscosity, and water content of the product spilled. It is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea surface with diesel fuel on it during this 24- hour period would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and weather conditions.

The ADIOS2 results coupled with spill trajectory information for a large spill discussed in Section A.9.3 indicate that a small fuel spill would not have any impacts on coastal or shoreline resources. The lease area is 261 km (162 miles) from the nearest shoreline. Modeling results discussed in Section A.9.3 indicate that a spill in the lease area would have a 4% or less probability of reaching the coastal areas ofLouisiana within 10 days after a spill. By that time, essentially 100% of a small fuel spill would have been dispersed or evaporated by natural processes, without taking into account ExxonMobil’s response measures. Slicks from spills are expected to persist for relatively short periods of time ranging from minutes (<1 bbl) to hours (<10 bbl) to a few days (10 to 1,000 bbl) and rapidly spread out, evaporate, and disperse into the water column (BOEM, 2012b). It is unlikely that a spill on the OCS would make landfall prior to dissipation because of the distance to shore and lack of persistence for such a spill (BOEM, 2012b).

Spill Response . In the unlikely event the shipboard prevention procedures fail to prevent a fuel spill, response equipment and trained personnel would be activated so that any spill effects would be localized and result only in short-term environmental consequences. EP Section 9 provides a detailed discussion of ExxonMobil’s response to a spill.

A.9.3 Crude Oil Spill (Worst Case Discharge)

Spill Size . In accordance with requirements of NTL 2010-N06, ExxonMobil has estimated a WCD for this EP as 175,895 barrels of oil per day. The detailed analysis of this calculation can be found in EP Section 2.

Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a deep drilling blowout during exploration drilling based on U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout frequency of 0.0017 per exploratory well for non-North Sea locations (International Association of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEM is in the process of updating these spill frequency estimates to include the recent Macondo event; however, significant changes to the spill rates for the entire OCS are not anticipated (BOEMRE, 2011a; BOEM, 2012d). As noted in the Introduction , the baseline risk of a catastrophic blowout is estimated to be once every 26 years (BSEE Final Drilling Safety Rule, 75 FR 63365).

Included in EP Section 2 are ExxonMobil’s calculations and information as required by NTL 2010-N06, including descriptions of measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout. ExxonMobil will also comply with NTL 2010-N10 and the Final Drilling Safety Rule, which specifies additional safety measures for OCS

activities.

Spill Trajectory . The fate of a large oil spill in the lease area would depend on meteorological and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a computer simulation of oil spill transport that uses realistic data for winds and currents to predict spill fate. Although this model has received some criticism recently (Earthjustice, 2011), it is still the most widely scientifically accepted model for estimating the fate of small fuel spills. The primary criticism of the OSRA model results as provided in Ji et al. (2004) was that the model did not evaluate the fate of a spill over time periods longer than 30 days, nor did it predict the fate of a release that continues over a period of weeks or months, as in the Macondo incident. Also as noted by Ji et al. (2004), the OSRA model does not take into account the chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response activities. The model does not assume a particular spill size but has generally been used by the BOEM to evaluate contact probabilities for spills greater than 1,000 bbl.

To address this criticism, a special OSRA run was conducted for the recent BOEM Western and Central Gulf of Mexico Planning Area Supplemental EISs (BOEMRE, 2011a; BOEM, 2012b) in order to estimate the impacts of a possible future catastrophic long-duration oil spill. In this OSRA model run, a hypothetical high volume, long-duration oil spill was assumed to have occurred, and the analysis emphasized modeling a spill that continued for 90 consecutive days, with each trajectory tracked for up to 120 days.The OSRA model run for this revised analysis was conducted for five hypothetical launch points in the Central and Western Gulf of Mexico Planning Areas. These launch points were deliberately located in areas identified as having a high possibility of containing large oil reserves.

The five launch point areas were as follows:

1. Central Gulf of Mexico shelf area west of the Mississippi River (28.98660° N latitude, 92.17851° W longitude);

2. Central Gulf of Mexico shelf area east of the Mississippi River (29.91388° N latitude, 88.15338° W longitude);

3. Central Gulf of Mexico slope area (27.31998° N latitude, 90.22203° W longitude);

4. Western Gulf of Mexico shelf area (27.55423° N latitude, 96.76627° W longitude); and

5. Western Gulf of Mexico slope area (27.51367° N latitude, 94.51836° W longitude).

The results for Launch Point 3, the launch point nearest to the project area, are presented in Table 3

.Table 3. Conditional probabilities expressed as percent chance that an oil spill starting at Launch Point 3 will contact a certain parish, county, or coastline within 120 days (Modified from: BOEM, 2012b, Appendix C).

Season Winter Spring Summer Fall

Day 0 0 20 0 0 20 0 0 20 0 0 20 County or Parish,

State Percent Chance

Cameron, Texas

- - - - - - - - - - - - -
Willacy, Texas

- - - - - - - - - - - - -
Kenedy, Texas

- - - - - - - - - - - -
Kleberg, Texas

- - - - - - - - - - -

Nueces, Texas

- - - - - - - - - - -

Aransas, Texas

- - - - - - - - - - - -
Calhoun, Texas

- - - - - - - - - - -
Matagorda, Texas - - 7 - - - - - 1 - -

Brazoria, Texas - - 2 - - - - - -
Galveston, Texas

- - 0

- - - - - -
Jefferson, Texas

- - - - - - - - - Cameron,
Louisiana - - - - 1 2 - - - - Vermilion,

Louisiana

- - - - - - - - -
Iberia, Louisiana

- - - - - - - - - - - - - Terrebonne,

Louisiana - - 2 4 - - - - - - - Lafourche,

Louisiana - - - 0 - - - - - - Jefferson,

Louisiana

- - - - - - - - - - - Plaquemines,

Louisiana

- - - - 0 2

- - - - - - Jackson, Mississippi - - - - - - - - - - - - - -
Baldwin, Alabama

- - - - - - - - - - - - - -
Bay, Florida

- - - - - - - - - - - - - - -
Franklin, Florida

- - - - - - - - - - - - - - -
Monroe, Florida

- - - - - - - - - - - - - -
Dade, Florida

- - - - - - - - - - - - - - -"—" = Values <1.0%. Areas where there is <0.5% chance of contact within 120 days are not shown.

OSRA is a preliminary risk assessment model. In the event of an actual oil spill, real-time monitoring and trajectory modeling would be conducted using current and wind data available from the rigs and permanent production structures in the area. Satellite and aerial monitoring of the plume and real-time trajectory modeling using wind and current data would continue on a daily basis to help position equipment and human resources throughout the duration of any major spill or uncontrolled release.

Weathering . Following an oil spill, several physical, chemical, and biological processes, collectively called weathering, interact to change the physical and chemical properties of the oil, influencing potential effects to marine organisms and ecosystems. The most important weathering processes include spreading, evaporation, dissolution, dispersion into the water column, formation of water-in-oil emulsions, photochemical oxidation, microbial degradation, adsorption to suspended particulate matter, and stranding on shore or sedimentation to the seafloor (National Research Council, 2003b).

Weathering decreases the concentration of oil and produces changes in its chemical composition, physical properties, and toxicity. The more toxic, light aromatic and aliphatic hydrocarbons are lost rapidly by evaporation and dissolution from a slick on the water surface. Evaporated hydrocarbons are degraded rapidly by sunlight. Biodegradation of oil on the water surface and in the water column by marine bacteria removes first the n-alkanes and then the light aromatics from the oil. Other petroleum components are biodegraded more slowly. Photo-oxidation attacks mainly the medium and high molecular weight PAHs in the oil on the water surface.

Spill Response . BOEM has issued recent NTLs following the Macondo spill that clarify additional oil spill prevention and response planning requirements. These NTLs are summarized in Table 2 , and additional BOEM (2012b) guidance is provided below.

**NTL 2012-N06 – Guidance to Owners and Operators of Offshore Facilities Seaward of the Coast Line Concerning Regional Oil Spill Response Plans:**  This NTL, effective 10 August 2012, provides clarification, guidance, and information on the preparation and submittal of regional OSRPs for owners and operators of oil handling, storage, or transportation facilities, inclusive of pipelines,located seaward of the coastline. It states that lessees, designated operators, and pipeline right-ofway holders are responsible for preparation and submission of these plans. Some of the clarifications and recommended practices in the NTL are based on lessons learned from the Macondo oil spill

response.

**NTL 2010-N10** – **Statement of Compliance with Applicable Regulations and Evaluation of Information Demonstrating Adequate Spill Response and Well Containment Resources**  : This NTL, effective 8 November 2010, applies only to operators conducting operations using subsea or surface BOPs on floating facilities. It requires that lessees and operators must submit a statement signed by an authorized company official with each well permit application indicating that they will conduct all of their authorized activities in compliance with all applicable regulations, including the Increased Safety Measures Regulations at 75 FR 63346. The NTL also informs lessees that BOEMRE will evaluate whether the operator has submitted adequate information demonstrating that it has access to and can deploy surface and subsea containment resources that would be adequate to promptly respond to a blowout or other loss of well control. The NTL notifies the operator that BOEMRE intends to evaluate the adequacy of each operator to comply in the operator’s current OSRP; therefore, there is an incentive for voluntary compliance.

**NTL 2010-N06 – Information Requirements for Exploration Plans, Development and Production Plans,**  **and Development Operations Coordination Documents on the OCS :**  This NTL, effective 18 June 2010, explains the procedures for the lessee or operator to submit supplemental information for new or previously submitted EPs, Development and Production Plans,or Development Operations Coordination Documents. The required supplemental information includes the following: (1) a description of the blowout scenario as required by 30 CFR 254(b) and 254(h); (2) a description of their assumptions and calculations used in determining the volume of the WCD required by 30 CFR 254.26; and (3) a description of the measures proposed that would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and early intervention in the event of a blowout, including the arrangements for drilling relief wells and any other measures proposed. The early intervention methods of the third requirement could actually include the surface and subsea containment resources that BOEM announced in NTL 2010- N10, which states that BOEM will review to ensure that the measures are adequate to promptly respond to a blowout or other loss of well control.

• ExxonMobil submitted an updated Gulf of Mexico Regional OSRP to BOEM in December 2010 and July and December 2011; the ORSP is pending approval. The OSRP provides a detailed plan for ExxonMobil to respond rapidly to and effectively manage oil spills that may result from drilling and production operations.

In the event of a WCD, ExxonMobil has access to surface and subsea response/containment capabilities that could be implemented through various organizations under contract. ExxonMobil's primary spill response equipment provider is Clean Gulf Associates (CGA).

CGA has four skimming vessels capable of operating in shallow waters and offshore/nearshore areas. These vessels have oleophilic brush pack skimming systems operating in troughs built into the hulls, below-deck storage, and marine electronics packages including marine, aircraft and company-frequency radios; radar; moving map plotters; GPS; satellite phones; and depth finders. CGA also offers nine Fast Response Systems staged throughout the Gulf of Mexico that are available for offshore use.

The CGA high-volume open sea skimmer (HOSS) barge consists of a skimming system built into an oil recovery barge. There are four 1,000-bbl recovered oil storage tanks built into the hull where oil can be separated and offloaded. Skimming operations are conducted from the control room overlooking the skimmer deck. The estimated daily recovery capacity for the HOSS barge is approximately 43,000 bbl.

CGA is currently adding to its equipment stockpile and has acquired 11 sets of Koseq skimming arms and two Aqua Guard skimmers. In addition, an x-band radar/infrared tracking system is installed on the HOSS barge. Additional CGA equipment can be referenced on their website: http://www.cleangulfassoc.com/

.
ExxonMobil also has a contract with the Marine Spill Response Corporation (MSRC) for additional spill response equipment. MSRC has a dedicated fleet for the Atlantic/Gulf of Mexico region and additional available equipment staged throughout the U.S. MSRC equipment staged throughout the Gulf of Mexico includes seven oil spill response vessels, two fast response vessels, five oil spill response barges, five platform supply vessels, and 15 shallow water barges. Various equipment is outfitted with x-band and infrared technology.

MSRC recently completed a large expansion of its resources and capabilities in the Gulf of Mexico, with particular focus on deepwater. Additional information on MSRC capabilities and a complete equipment listing are available on-line at http://www.msrc.org/

.

See EP Section 9 for a detailed description of ExxonMobil’s site-specific response to the WCD for this plan.

A.9.4 Other Accidents Not Analyzed in Detail

BOEM (2012b) discusses three other types of accidents: chemical spills, vessel collisions, and loss of well control. The information from the EIS on these topics remains valid and is incorporated by reference into this document. These accidents are discussed briefly below along with a hydrogen sulfide (H 2 S) release. There are no other site-specific issues for the drilling of the well proposed in this EP.Chemical Spills . Chemicals are stored and used to condition drill muds and during production and in well completions, stimulation, and workover procedures. The relative quantity of their use is reflected in the largest volumes spilled. Completion fluids are the largest quantity used and comprise the largest releases. Between 5 and 15 chemical spills are anticipated each year, with the majority being <50 bbl in size. The most common chemicals spilled are methanol, ethylene glycol, and zinc bromide. Additional production chemicals are needed in deepwater operations where gas hydrates tend to form. Spill volumes are anticipated to remain about the same, but spill frequency can be expected to decrease because of advances in subsea processing (BOEMRE, 2011a; BOEM, 2012b).

Riser Disconnect SBM Spills . In deepwater drilling, SBMs are preferred over petroleum oil-based muds (OBMs) due to the superior environmental properties of SBMs. The synthetic base fluids used in SBMs are less toxic to the marine environment and have the potential to biodegrade. SBMs have been used in the Gulf of Mexico since the mid-1990s, and between 5 and 20 SBM releases are anticipated each year as a result of offshore drilling programs. The majority of these releases are <50 bbl in size, but accidental riser disconnects may result in the release of medium (238 to 2,380 bbl) to large (>2,381 bbl) quantities of drilling fluids. Riser disconnect accidents are of particular concern when SBMs are in use (BOEMRE, 2011b).

Vessel Collisions . BOEM data show that from 1996 to 2009 there were 226 OCS-related collisions. Most collision mishaps are the result of service vessels colliding with platforms or vessel collisions with pipeline risers. Approximately 10% of vessel collisions with platforms in the OCS resulted in diesel spills, and in several collision incidents, fires resulted from hydrocarbon releases. To date, the largest diesel spill associated with a collision occurred in 1979 when an anchor-handling boat collided with a drilling platform in the Main Pass lease area, spilling 1,500 bbl. Diesel fuel is the product most frequently spilled, but oil, natural gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been released as the result of vessel collisions. Human error accounted for approximately half of all reported vessel collisions from 2006 to 2009. As summarized in MMS (2007b) and BOEM (2012b), vessel collisions occasionally occur during routine operations. Some of these collisions have caused spills of diesel fuel or chemicals. ExxonMobil will comply with all USCG- and BOEM-mandated safety requirements to minimize the potential for vessel collisions.

Loss of Well Control . A loss of well control is the uncontrolled flow of a reservoir fluid that may result in the release of gas, condensate, oil, drilling fluids, sand, or water. Loss of well control is a broad term that includes very minor up to the most serious well control incidents, while blowouts are considered to be a subset of more serious incidents with greater risk of oil spill or human injury (MMS, 2007b). Loss of well control may result in the release of synthetic drilling fluid or loss of oil. ExxonMobil has a robust system in place to prevent loss of well control. Measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout are described in the NTL 2010-06 package submitted with the EP, as required. The potential for a loss-of-well-control event will be minimized by adhering to the requirements of applicable regulations such as the Final Drilling Safety Rule and NTL 2010-N10, which specify additional safety measures for OCS activities.

H 2 S Release . Pursuant to 30 CFR 550.215, ExxonMobil is requesting in the EP that the BOEM Regional Supervisor, Field Operations, classify the area in the proposed drilling operations as H 2 S absent.

# B. Affected Environment

The lease area is in the central Gulf of Mexico, 261 km (162 miles) from the nearest shoreline, and 287 km (178 miles) from the onshore support base at Port Fourchon, Louisiana ( Figure 1 ).

Based on the geohazard assessment conducted by Gardline Surveys Inc. (2010), water depth at the wellsite is anticipated to be 1,937 m (6,354 ft) ( Figure 2 ). There are no seafloor faults, mounds, depressions, or other significant seafloor features at the proposed well location. There is no evidence of fluid expulsion features, or high-density deepwater benthic communities near the proposed wellsite (Gardline Surveys Inc., 2010). A detailed description of the regional affected environment, including meteorology, oceanography, geology, air and water quality, benthic communities, threatened and endangered species, biologically sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses is provided in lease sale EISs (MMS, 2007b; BOEM, 2012b). These regional descriptions remain valid and are incorporated by reference. General background information is presented below, and brief descriptions of each potentially affected resource, including site-specific and/or new information if available, are presented in Section C

.

The Macondo spill resulted in impacts to water quality in the area of the spill. In addition to the oil slick on the sea surface, plumes of submerged oil droplets were produced when subsea dispersants were applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). Despite limited information on the water quality of deep water, it is clear that conditions in the offshore waters of the Gulf of Mexico were altered by the Macondo event. Various monitoring efforts and environmental studies are in progress, but it is not currently possible to precisely estimate the long-term impacts the spill will have on offshore water quality (BOEMRE, 2011a; BOEM, 2012a).

The lease area is located approximately 348 km (216 miles) southwest of the Macondo spill site. Based on an analysis of satellite imagery, the surface slick did not extend over the lease area, and the existing water quality in the lease area is not expected to have been affected by the Macondo release. Prior to the Macondo incident, water quality in deep, offshore waters of the Gulf of Mexico was expected to be good, with low levels of contaminants (Kennicutt, 2000). Based on the information currently available, there is no reason to expect any long-term change in water quality conditions in the lease area from those predicted in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the Programmatic EIS (BOEM, 2012d).Figure 2. Bathymetric map of the lease area showing the surface hole location of Well "A" in Walker Ridge Block 282.

# C. Impact Analysis

This section analyzes the potential direct and indirect impacts of routine activities and accidents. Impacts have been analyzed extensively in multi-lease-sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b; BOEM, 2012b). The information in these documents is incorporated by reference. Potential site-specific issues are addressed in this section.

C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site-specific air quality data for the project area due to the distance from shore. Because of the distance from shore-based pollution sources and the lack of sources offshore, air quality at the wellsite is expected to be good. The attainment status of Federal OCS waters is unclassified because there is no provision in the Clean Air Act for classification of areas outside State waters (MMS, 2007b).

As noted earlier, based on calculations made pursuant to applicable regulations, emissions from drilling activities are not expected to be significant as they are below exemption levels. Therefore, the only potential effects to air quality would be from routine air pollutant emissions, a small fuel spill, and a large oil spill (WCD).

BOEM has reexamined the analysis for air quality presented in MMS (2007b, 2008) based on additional information and in consideration of the Macondo oil spill event. No substantial new information was found that would alter the potential impacts on air quality presented in previous lease sale EISs (BOEMRE, 2011a; BOEM, 2012b).

Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pollutant emissions will result from the drillship operations and helicopters and service vessels. These emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel-powered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended PM, SO
x , NO x , VOCs, and CO. Emissions of pollutants into the atmosphere from these activities are not projected to have significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates and heights, and resulting pollutant concentrations. As described in recent lease sale EISs, the incremental contribution to cumulative impacts from activities similar to ExxonMobil’s proposed activities is not significant and will not cause or contribute to a violation of any National Ambient Air Quality Standard (NAAQS) (MMS, 2007b, 2008). Since the BOEM completed the lease sale EISs, the USEPA has adopted a new short-term NAAQS for nitrogen dioxide (NO 2 ). The standard has not yet been implemented in the Gulf Coast states, but given the levels of expected emissions and the distance of the project from shore, emissions from the activities described in ExxonMobil’s proposed EP are not likely to contribute to violations of any NAAQS onshore.

Carbon dioxide (CO 2 ) and methane (CH 4 ) emissions from the project would constitute a small incremental contribution to greenhouse gas emissions from all OCS activities. According to recent programmatic and OCS lease sale EISs (BOEM, 2012a,d), estimated CO 2 emissions from OCS oil and gas sources are 0.4% of the U.S. total. All OCS activities contribute approximately 0.005% to total global CO 2 emissions. Greenhouse gas emissions may contribute to climate change, with important effects on temperature, rainfall, frequency of severe weather, ocean acidification, and sea level rise (Intergovernmental Panel on Climate Change, 2007). Greenhouse gas emissions from this proposed project represent a negligible contribution to the total greenhouse gas emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in the Programmatic EIS (BOEM, 2012d).Because of the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast, including nonattainment areas. As noted in the lease sale EIS (MMS, 2007b), emissions of air pollutants from routine activities in the Central Gulf of Mexico Planning Area 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 Air Quality Emissions Report (see EP Section 8 and Appendix F) prepared in accordance with BOEM requirements shows that the projected emissions are below exemption levels; therefore, according to 30 CFR 250.303, the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required.

The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is designated under the Clean Air Act as a Prevention of Significant Deterioration Class I air quality area. The BOEM is required to notify the National Park Service and U.S. Fish and Wildlife Service (USFWS) if emissions from proposed projects may affect the Breton Class I area. Additional review and mitigation measures may be required for sources within 186 miles (300 km) of the Breton Class I area that exceed emission limits agreed upon by the administering agencies (National Park Service, 2010). The lease area is approximately 358 km (222 miles) from the Breton Wilderness Area, and no air quality impacts on the Wilderness Area are expected. ExxonMobil will comply with all BOEM requirements regarding air emissions.

Impacts of a Small Fuel Spill

Potential impacts of a small spill on air quality are expected to be consistent with those analyzed and discussed in EISs prepared for lease sales (MMS, 2007b; BOEM, 2012b) and the current Programmatic EIS (BOEM, 2012d). The probability of a small spill would be minimized by ExxonMobil’s preventative measures during routine operations, including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will reduce the potential impacts. EP Section 9 includes a detailed discussion of the spill response measures that would be employed. Given the open ocean location of the lease area, the extent and duration of air quality impacts from a small spill would not be significant.

A small fuel spill would affect air quality near the spill site by introducing VOCs through evaporation. The ADIOS2 model (see Section A.9.2 ) indicates that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and weather conditions.

A small fuel spill would not affect coastal air quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on air quality are expected to be consistent with those analyzed and discussed in lease sale EISs (MMS, 2007b; BOEM, 2012b) and the current Programmatic EIS (BOEM, 2012d).

A large oil spill (WCD) could potentially affect air quality by introducing VOCs through evaporation from the slick. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Real-time wind and current data from the project area would be available at the time of a spill and would be used to assess the fate and effects of VOCs released. Additional air quality impacts could occur if response measures included **in situ** burning of the floating oil. Burning would generate a plume of black smoke and result in emissions of NOx, SO x , CO, and PM, as well as greenhouse gases. However, **in situ** burning would occur only after
authorization from the USEPA.

Because of the lease area location (261 km [162 miles] from the nearest shoreline), most air quality impacts would occur in offshore waters with minimal chance to affect onshore air quality.C.1.2 Water Quality

There are no site-specific water quality data for the lease area. Because the lease location is in deep, offshore waters, water quality is expected to be good, with low levels of contaminants. As noted in a lease sale EIS (MMS, 2007b), deepwater areas in the northern Gulf of Mexico are relatively homogeneous with respect to temperature, salinity, and oxygen. Kennicutt (2000) noted that the deepwater region has little evidence of contaminants in the dissolved or particulate phases of the water column. However, there are localized occurrences of natural seepage of oil, gas, and brines in near-surface sediments and up through the water column.

The lease area is located approximately 348 km (216 miles) from the Macondo spill site. Based on the general circulation pattern seen in the Gulf of Mexico and satellite imagery, the surface slick from that discharge did not extend over the lease area during the spill, and the existing water quality in the lease area is not expected to have been affected by the Macondo release.

IPFs potentially affecting water quality are effluent discharges and two types of accidents: a small fuel spill and a large oil spill (WCD).

Impacts of Effluent Discharges

In general, turbid water can be expected to extend between a few hundred meters and several kilometers down current from the discharge point for water-based drilling muds and cuttings. SBMs will be collected on the rig and either reused by the vendor or transported to Port Fourchon for recycling and/or disposal in an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit. All NPDES permit limitations and requirements will be met. There will be no persistent impacts on water quality in the lease area (National Research Council, 1983; Neff, 1987; Neff et al., 2000).

Treated sanitary and domestic wastes, including those from support vessels, may have a slight transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and requirements and USCG regulations (as applicable) will be met, therefore, little or no impact on water quality is anticipated.

Deck drainage includes all effluents resulting from rain, deck washings, and runoff from curbs, gutters, and drains, including drip pans in work areas. Rainwater that falls on uncontaminated areas of the drilling rig will flow overboard without treatment. However, rainwater that falls on the drilling rig deck and other areas such as chemical storage areas and places where equipment is exposed will be collected and oil and water separated to meet NPDES permit requirements. Based on adherence to permit limits and applicable regulations, little or no impact on water quality is anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water, are expected to be diluted rapidly, resulting in little or no impact on water quality.

Impacts of a Small Fuel Spill

Potential impacts of a small spill on water quality are expected to be consistent with those analyzed and discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b). The probability of a small spill would be minimized by ExxonMobil’s preventative measures during routine operations, including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will potentially help mitigate and reduce the impacts. EP Section 9 provides detail on spill response measures in addition to the summary information provided in this EIA. Given the open ocean location of the lease area, the extent and duration of water quality impacts from a small spill would not be significant.A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. However, it is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours (see Section A.9.2 ). The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and weather
conditions.

The water-soluble fractions of diesel are dominated by two- and three-ringed PAHs, which are moderately volatile (National Research Council, 2003b). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Because the density of diesel is less than the density of seawater, diesel will not sink and pool on the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solid loads (National Research Council, 2003b) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

A small fuel spill would not affect coastal water quality because the spill would not be expected to make landfall or reach coastal waters due to both response efforts that would be undertaken as well as natural attenuation (see Section A.9.2 ).

Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on water quality are expected to be consistent with those analyzed and discussed in lease sale EISs (MMS, 2007b; BOEM, 2012b) and the current Programmatic EIS (BOEM, 2012d). A large spill would affect water quality by producing a slick on the water surface and increasing the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Most of the oil would be expected to form a slick at the surface, although new information from the Macondo spill indicates that plumes of submerged oil droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). However, dispersants would be applied only after approval from the USEPA. Small droplets in the water may adhere to suspended sediments and be removed from the water column (Operational Scientific Advisory Team, 2010).

Because of the lease area location (261 km [162 miles] from the nearest shoreline), it is expected that most water quality impacts would occur in offshore waters, especially in the event of a spill lasting less than 30 days ( Table 3 ).

C.2 Seafloor Habitats and Biota

Water depth at the proposed project area is approximately 1,937 m (6,354 ft). There are no seafloor faults, mounds, depressions, or other significant seafloor features at the proposed well location. No areas of possible hard bottom or microseepages were seen within 610 m (2,000 ft) of the wellsite (Gardline Surveys Inc., 2010).

Based on the absence of hard bottom areas detected by side-scan sonar during the site clearance survey, the seafloor within 610 m (2,000 ft) of the wellsite is expected to consist mainly of soft bottom communities. The geohazard assessment did not identify any features that could support high-density deepwater benthic communities within 610 m (2,000 ft) of the wellsite. No areas of gaseous sediments or possible hydrocarbon seepage were defined within 610 m (2,000 ft) of the wellsite, and the presence of chemosynthetic communities is considered negligible (Gardline Surveys Inc., 2010).C.2.1 Soft Bottom Benthic Communities

There are no site-specific benthic community data from the lease area. However, data from the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Wei, 2006; Rowe and Kennicutt, 2009) can be used to describe typical benthic communities in the area. Table 4 summarizes data collected at stations in water depths similar to the proposed drilling area.

Table 4. Benthic community data from stations near the lease area and in similar water depths sampled

during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Adapted from: Wei, 2006; Rowe and Kennicutt, 2009).

Statio

n Water

Depth (m) Abundance

Meiofauna (individuals/m 2 ) Macroinfauna (individuals/m 2 ) Megafauna (individuals/ha)

NB5 2,063 117,263 706 1,600

NB3 1,875 165,245 1,342 191

Meiofaunal and megafaunal abundances from Rowe and Kennicutt (2009); macroinfaunal abundance from Wei (2006).

Densities of meiofauna (animals passing through a 0.5-mm sieve but retained on a 0.062-mm sieve) in water depths representative of the lease area (1,937 m [6,354 ft]) typically range from approximately 120,000 to 290,000 individuals/m 2 (Rowe and Kennicutt, 2009). Nematodes, nauplii, and harpacticoid copepods were the three dominant meiofaunal groups, accounting for about 90% of total abundance.

The benthic macroinfauna is characterized by small mean individual sizes and low densities, both of which reflect the meager primary production in Gulf of Mexico surface waters (Wei, 2006). Densities decrease exponentially with water depth. Based on an equation presented by Wei (2006), macroinfaunal densities in the water depths of the lease area are expected to be about 1,620 individuals/m 2

.

Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of Mexico continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) recognized four depth-dependent faunal zones (1 through 4), two of which are divided horizontally. The lease area is in Zone 3W, which includes the Alaminos Canyon (basin and non-basin sites) as well as the base of the Sigsbee Escarpment, with stations ranging in depth from 6,152 to 9,869 ft (1,875 to 3,008 m). The most abundant species in Zone 3W were the polychaetes **Levinsenia uncinata, Paraonella monilaris** , and **Tachytrypane** sp. A; the bivalve **Heterodonta** sp. B; and the isopod **Macrostylis** 256. Megafaunal densities from nearby stations ranged from 191 to 1,600 individuals/ha ( Table 4 ). Common megafauna included motile groups such as decapods, ophiuroids, holothurians, and demersal fishes, as well as sessile groups such as sponges and anemones.

Bacteria also are an important component in terms of biomass and cycling of organic carbon (Cruz-Kaegi, 1998). Bacterial biomass at the depth range of the lease area typically is about 1 to 2 g C/m 2 in the top 15 cm of sediments (Rowe and Kennicutt, 2009).

IPFs potentially affecting benthic communities are physical disturbance to the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) resulting from a well blowout at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.

Impacts of Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP are located. Depending upon the specific well configuration, this area is generally about 0.25 ha (0.62 ac).The areal extent of these impacts from the DP drillship will be small compared to the lease area itself, and these types of soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from the physical disturbance of the seafloor during this project will have no significant impact on soft bottom benthic communities in the region.

Impacts of Effluent Discharges

Drilling muds and cuttings are the only effluents that are likely to affect benthic communities. During initial well interval(s) before the marine riser is set, cuttings and seawater-based "spud mud" will be released at the seafloor. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Cement slurry components typically include cement mix and some of the same chemicals used in water-based drilling muds (Boehm et al., 2001). The main impacts will be burial and smothering of benthic organisms within several meters to tens of meters around the wellbore. Soft bottom sediments disturbed by cuttings, drilling muds, and cement slurry will eventually be recolonized through larval settlement and migration from adjacent areas. Because some deep-sea biota grow and reproduce slowly, recovery may require several years.

Discharges of washed SBM cuttings from the rig may affect benthic communities, primarily within several hundred meters of the wellsite. The fate and effects of SBM cuttings have been reviewed by Neff et al. (2000), and monitoring studies have been conducted in the Gulf of Mexico by Continental Shelf Associates, Inc. (2004, 2006). In general, washed cuttings with adhering SBMs tend to clump together and form thick cuttings piles close to the drillsite. Areas of SBM cuttings deposition may develop elevated organic carbon concentrations and anoxic conditions (Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate in concentrations of approximately 1,000 mg/kg or higher, benthic infaunal communities may be adversely affected due to both the toxicity of the base fluid and organic enrichment (with resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that tolerate low oxygen and high H 2 S predominate (Continental Shelf Associates, Inc., 2006). As the base synthetic fluid is decomposed by microbes, the area will gradually return to pre-drilling conditions. Disturbed sediments will be recolonized through larval settlement and migration from adjacent areas.

The areal extent of impacts from drilling discharges will be small. Assuming a typical effect radius of 500 m (1,640 ft), the affected area around the wellsite would represent about 3% of the seafloor within a lease block. Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project will have no significant impact on soft bottom benthic communities in the region.

Impacts of a Large Oil Spill (WCD)

The most likely effects of a subsea blowout on benthic communities would be within a few hundred meters of the wellsite. The MMS (2007b) estimated that a severe subsurface blowout could resuspend and disperse sediments within a 300-m (984-ft) radius. While coarse sediments (sands) would probably settle at a rapid rate within 400 m (1,312 ft) from the blowout site, fine sediments (silts and clays) could be resuspended for more than 30 days and dispersed over a much wider area. Based on previous studies, surface sediments at the project area are assumed to largely be silt and clay (Rowe and Kennicutt, 2009).Previous lease sale EISs (MMS, 2007a, 2008) indicated that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles (35 km) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 300-m (984-ft) radius estimated by MMS (2007a, 2008), depending on its extent, trajectory, and persistence. This contact could result in smothering and/or toxicity to benthic organisms. The affected area would be recolonized by benthic organisms over a period of months to years (National Research Council, 2003b).

C.2.2 High-Density Deepwater Benthic Communities

As defined by NTL 2009-G40, high-density deepwater benthic communities are features or areas thatcould support high-density chemosynthetic communities, or features or areas that could support highdensity deepwater corals and other associated high-density hard bottom communities. Chemosynthetic communities were discovered in the central Gulf of Mexico in 1984 and have been studied extensively (MacDonald, 2002). Deepwater coral communities are also known from numerous locations in the Gulf of Mexico (Brooke and Schroeder, 2007; CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities.

The nearest known chemosynthetic community site is approximately 111 km (69 miles) north-northeast of the lease area in Green Canyon Block 287. The nearest identified deepwater coral communities are in Green Canyon Block 852, 49 km (30 miles) north-northwest of the lease area.

The geohazard assessment of the lease area did not identify any features that could support high-density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling mud/cuttings discharge locations (Gardline Surveys Inc., 2010).

IPFs potentially affecting high-density deepwater benthic communities include physical disturbance of the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.

Impacts of Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP are located. Depending upon the specific well configuration, this area is generally about 0.25 ha (0.62 ac).

The areal extent of these impacts from the DP drillship will be small, and NTL 2009-G40 requires that high-density deepwater benthic communities and features or areas that could support high-density chemosynthetic communities or deepwater coral communities be avoided. Based on the information presented in Gardline Surveys Inc. (2010), there will be no impacts on chemosynthetic or deepwater coral communities from this project.

Impacts of Effluent Discharges

The geohazard assessment (Gardline Surveys Inc., 2010) did not identify any features that could support high-density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling locations, and the presence of chemosynthetic communities in the lease area is considered negligible. Monitoring programs on the Gulf of Mexico continental slope have shown that benthic impacts from drilling discharges typically are concentrated within about 500 m (1,640 ft) of the wellsite, although detectable deposits may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al.,2005). Because of the water depth of the lease area, drilling discharges would be expected to result in thinner, more diffuse accumulations on the seafloor than those documented in the literature. Although small amounts of cuttings particles may reach areas inhabited by high-density deepwater benthic communities, the discharges are not expected to result in significant impacts to these communities.

Impacts of a Large Oil Spill (WCD)

The current Programmatic EIS (BOEM, 2012d) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 35 km (22 miles) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact high-density deepwater benthic communities beyond the 300-m (984-ft) radius estimated by BOEM (2012d), depending on its extent, trajectory, and persistence. Oil plumes that contact sensitive benthic communities before degrading could potentially impact the resource (BOEM, 2012b). Potential impacts on sensitive resources would be an integral part of the decision and approval process for the use of dispersants, and such approval would be obtained from the USEPA prior to the use of dispersants.

The biological effects and expected fate of the oil remaining in the Gulf of Mexico from the Macondo blowout are still unknown due to the depth and the magnitude of this event. Hazen et al. (2010) reported changes in plume hydrocarbon composition with distance from the source. Incubation experiments with environmental isolates demonstrated faster-than-expected hydrocarbon biodegradation rates at 5°C. Based on these results, Hazen et al. (2010) suggested the potential exists for intrinsic bioremediation of the oil plume in the deep water column without substantial oxygen drawdown.

Potential impacts of oil on high-density deepwater benthic communities are discussed in MMS (2007b). Although chemosynthetic communities live among hydrocarbon seeps, natural seepage is very constant and occurs at low rates compared to the potential rates of oil release from a blowout. In addition, seep organisms also require unrestricted access to oxygenated water at the same time as exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment particles could come into contact with chemosynthetic organisms or deepwater corals. As discussed by MMS (2007b), impacts could include loss of habitat, biodiversity, and live coral coverage; destruction of hard substrate; change in sediment characteristics; and reduction or loss of one or more commercial and recreational fishery habitats. Sublethal effects could be long-lasting and affect the resilience of coral colonies to natural disturbances (e.g., elevated water temperature and diseases) (BOEM, 2012d).

The potential for a spill to affect deepwater corals is indicated by preliminary findings from an October 2010 survey of deepwater coral habitats near the Macondo spill site (BOEMRE, 2010). Government and academic researchers were working at a site 1,400 m (4,600 ft) deep and approximately 11 km (7 miles) southwest of the Macondo wellhead when they observed dead and dying corals with sloughing tissue and discoloration. Much of the soft coral observed in an area measuring about 15 by 40 m (50 by 130 ft) was covered by what appeared to be a brown flocculent substance (floc). Out of 40 large corals, 90% were heavily affected and showed dead and dying parts and discoloration. Another site 400 m (1,312 ft) farther away had a colony of stony corals similarly affected and partially covered with a similar brown substance. Based on hopanoid petroleum biomarkers from the floc, researchers concluded that it contained oil from the Macondo spill. The injured and dead corals were in an area where a subsea plume of oil had been documented during the spill in June 2010; corals elsewhere in the Gulf of Mexico outside the area affected by the plume did not appear to be experiencing higher mortality. The research team concluded that the observed coral injuries likely resulted from exposure to the subsurface oil plume (White et al., 2012).C.2.3 Designated Topographic Features

The block is not within or near a designated topographic feature or a no-activity zone as identified in NTL 2009-G39. The nearest designated topographic feature is Jakkula Bank in Green Canyon Block 50, 147 km (91 miles) north-northwest of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to designated topographic features because of their distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth. Near-bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge.

C.2.4 Pinnacle Trend Area Live Bottoms

The lease area is not covered by the Live Bottom (Pinnacle Trend) Stipulation. As defined by NTL 2009-G39, the nearest pinnacles stipulation block is Main Pass Block 290, 382 km (237 miles)
northeast of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to pinnacle trend area live bottoms due to the distance from the lease area. A small fuel spill would float on
the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth. Near-bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge.

C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (Low-Relief) Stipulation, which pertains to seagrass communities and low-relief hard bottom reef within the Eastern Gulf of Mexico Planning Area blocks in water depths of 100 m (328 ft) or less and portions of Pensacola and Destin Dome Area blocks in the Central Gulf of Mexico Planning Area. The nearest block covered by the live bottom stipulation, as defined by NTL 2009-G39, is Destin Dome Block 573, approximately 443 km (275 miles) northeast of the
lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to eastern Gulf live bottom areas because of the distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth. Near-bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf.

C.3 Threatened, Endangered, and Protected Species and Critical Habitat

This section discusses species listed as endangered or threatened under the Endangered Species Act (ESA). In addition, it includes all marine mammal species in the region, which are protected under the Marine Mammal Protection Act (MMPA).

Endangered or threatened species that may occur in the project area and/or along the northern Gulf
Coast are listed in Table 5 . The table also indicates the location of critical habitat (if designated in the Gulfof Mexico). Critical habitat is defined as (1) specific areas within the geographical area occupied by the species at the time of listing, if they contain physical or biological features essential to conservation, and those features may require special management considerations or protection; and (2) specific areas outside the geographical area occupied by the species if the agency determines that the area itself is essential for conservation. The National Marine Fisheries Service (NMFS) has jurisdiction for ESA-listed cetaceans, sea turtles, and fishes in the Gulf of Mexico. The USFWS has jurisdiction for ESA-listed birds
and the West Indian manatee.

Table 5. Federally listed endangered and threatened species potentially occurring in the lease area and

along the northern Gulf Coast.

Species Scientific Name S

tatus Potential

Presence Critical Habitat

Designated in Gulf of
Mexico Leas
e Area Co

astal
Marine Mammals Sperm whale **Physeter macrocephalus** E X

-- None West Indian

manatee **Trichechus manatus latirostris**  E -- X Florida (Peninsular)

Blue whale **Balaenoptera musculus** E X a

-- None Fin whale **Balaenoptera physalus**  E X a

-- None Humpback whale **Megaptera novaeangliae** E X a

-- None North Atlantic right whale **Eubalaena glacialis** E X a

-- None

Sei whale **Balaenoptera borealis** E X a

-- None Sea Turtles Loggerhead turtle **Caretta caretta** T X X None

Green turtle **Chelonia mydas** T , E b X X None

Leatherback turtle **Dermochelys coriacea** E X X None

Hawksbill turtle **Eretmochelys imbricata** E X X None Kemp’s ridley turtle **Lepidochelys kempii** E X X None

Birds

Piping Plover **Charadrius melodus** T -- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane **Grus americana** E -- X Coastal Texas (Aransas National Wildlife Refuge)
Fishes

Gulf sturgeon **Acipenser oxyrinchus**

**desotoi** T -- X Coastal Louisiana, Mississippi, Alabama, and Florida (Panhandle)
Smalltooth sawfish **Pristis pectinata** E -- X Southwest Florida and the Florida Keys
Invertebrates
Elkhorn coral **Acropora palmata** E

-- X Flower Garden Banks
Terrestrial Mammals
Beach mice (Alabama, Choctawhatchee, Perdido Key,
St. Andrew) **Peromyscus polionotus** E -- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = endangered; T = threatened.

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to be present in the lease area.

b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.As mandated by the ESA, MMS consulted NMFS and the USFWS on possible and potential impacts from the proposed leasing in the Gulf of Mexico on endangered/threatened species and their designated critical habitat (MMS, 2007a,b). A Biological Assessment was prepared for each consultation. The formal ESA consultation with NMFS was concluded with receipt of the Biological Opinion on 3 July 2007 (NMFS, 2007). The Biological Opinion concludes that the proposed lease sales and associated activities in the Five-Year Leasing Plan for Western and Central Planning Areas 2007-2012 are not likely to jeopardize the continued existence of threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated critical habitat. The informal ESA consultation with USFWS was concluded with a letter dated 14 September 2007. The USFWS concurred with MMS’s determination that proposed actions of the Five-Year Leasing Plan were not likely to adversely affect threatened/endangered species or designated critical habitat under USFWS jurisdiction. Following the Macondo spill, BOEMRE requested to reinitiate an ESA consultation with both NMFS and USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on 24 September 2010, and the USFWS responded with a letter to BOEMRE on 27 September 2010. At present, the NMFS and USFWS have placed the consultation process on hold because they feel the environmental baseline information needs to be updated for the post-Macondo spill environment based on the results of the Natural Resource Damage Assessment (NRDA) process. The NRDA data have yet to be released, and the existing consultation remains in effect (BOEM, 2012b). The existing consultation recognizes that BOEM-required mitigations and other reasonable and prudent measures should reduce the likelihood of impacts from all BOEM-authorized activities in the Gulf of

Mexico.

Coastal endangered or threatened species that may occur along the northern Gulf Coast include the West Indian manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of beach mouse. Critical habitat has been designated for all of these species as indicated in Table 5 and discussed in
individual sections.

Two other coastal species (Bald Eagle and Brown Pelican) discussed in the MMS (2007b) and BOEM (2012b) lease sale EISs are no longer federally listed as endangered or threatened. These are discussed in
Section C.4.2

, Shorebirds and Coastal Nesting Birds

.

The sperm whale and five species of sea turtles are the only endangered or threatened species likely to occur at or near the lease area. No critical habitat has been designated for these species in the Gulf of

Mexico.

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of

Mexico.

C.3.1 Sperm Whale (Endangered)

The only endangered marine mammal likely to be present at or near the project area is the sperm whale ( **Physeter macrocephalus** ). Resident populations of sperm whales occur within the Gulf of Mexico; a species description is presented in a previous lease sale EIS (MMS, 2007b). Gulf of Mexico sperm whales are classified as an endangered species and a "strategic stock" (defined as a stock that may have unsustainable human-caused impacts) by NOAA Fisheries (Waring et al., 2012). No critical habitat for the sperm whale has been designated in the Gulf of Mexico.

The distribution of sperm whales in the Gulf of Mexico is correlated with mesoscale physical features suchas eddies associated with the Loop Current (Jochens et al., 2008). Sperm whale populations in the northcentral Gulf of Mexico are present there throughout the year (Davis et al., 2000). Results of a multi-year tracking study show female sperm whales typically concentrated along the upper continental slope between the 200- and 1,000-m (656- and 3,280-ft) depth contours (Jochens et al., 2008). Male sperm whales were more variable in their movements and were documented in water depths greater than3,000 m (9,843 ft). Generally, groups of sperm whales sighted in the Gulf of Mexico during the MMS-funded Sperm Whale Seismic Study (SWSS) consisted of mixed-sex groups comprising adult females and immatures, and groups of bachelor males. Typical group size for mixed groups was 10 individuals (Jochens et al., 2008). SWSS results show that sperm whales transit through the vicinity of the lease area. Movements of satellite-tracked individuals suggest that this area of the Gulf continental slope is within the home range of the Gulf of Mexico population (within the 95% utilization distribution) (Jochens et al., 2008).

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents–a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on sperm whales due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on sperm whales.

Current threats to sperm whale populations worldwide are discussed in a final recovery plan for the sperm whale recently published by NOAA (NMFS, 2010a). Threats are defined as "any factor that could represent an impediment to recovery," and include fisheries interactions, anthropogenic noise, vessel interactions, contaminants and pollutants, disease, injury from marine debris, research, predation and natural mortality, direct harvest, competition for resources, loss of prey base due to climate change and ecosystem change, and cable laying. In the Gulf of Mexico, the impacts from many of these threats are identified as either low or unknown (BOEMRE, 2011a; BOEM, 2012b).

Impacts of Drilling Rig Presence, Noise, and Lights

Noise generated from the drilling rig and from routine drilling activities has the potential to disturb sperm whales. Some sounds produced by the drilling rig may be emitted at levels that could potentially disturb individual whales or mask the sounds animals would normally produce or hear. Noise associated with drilling is relatively weak in intensity, and an individual animal’s noise exposure would be transient.

Sperm whales appear to have good low-frequency hearing, with variable responses to anthropogenicnoise (Jochens et al., 2008). Southall et al. (2007) lists sperm whales in the same hearing group (i.e., midfrequency cetaceans) as dolphins, toothed whales, beaked whales, and bottlenose whales (estimated hearing range of 150 Hz to 160 kHz). Generally, most of the acoustic energy from sperm whales is present at frequencies below 4 kHz, although diffuse energy up to and past 20 kHz has been reported, with source levels up to 236 dB re 1 μPa at 1 m.

Sounds produced during drill rig operations are generally constant (rather than pulsed or intermittent) and at levels that may be louder than, and of a similar frequency to, the auditory signal received by sperm whales. Animals can determine the direction from which a sound arrives based on cues, such as difference in arrival times, sound levels, and phases at the two ears. Thus, an animal’s directional hearing capabilities have a bearing on its vulnerability to masking (NRC, 2003b). Behavioral changes for marine mammals such as the sperm whale resulting from auditory masking sounds may include producing more calls, longer calls, or shifting the frequency of the calls (Holt et al., 2009; NMFS, 2009a).

There are other OCS facilities and activities near the lease area, and the region as a whole has a large number of similar noise sources. Drilling-related noise associated with this project will contribute to increases in the ambient noise environment of the Gulf of Mexico, but it is not expected in amplitudes sufficient to cause either hearing or behavioral effects to sperm whales.

The drilling rig used during the proposed activity will be located within a deepwater, open ocean environment and will remain stationary during drilling operations. Sounds generated by the rig and by drilling operations will be generally continuous with some variability in sound level. This analysis assumes that the continuous nature of sounds produced by the drilling rig will provide individual whales with cuesrelative to the direction and relative distance (sound intensity) of the sound source, and the fixed position of the drilling rig will provide multiple options for active avoidance of potential physical impacts.

NMFS analyzed the potential for impacts of drilling-related noise on sperm whales in its Biological Opinion for the Gulf of Mexico Oil and Gas Activities: Five-Year Leasing Plan for Western and Central Planning Areas 2007-2012 (NMFS, 2007). The analysis noted that drilling rigs emit low sound source levels and concluded that drilling is not expected to produce amplitudes sufficient to cause hearing or behavioral effects in sperm whales; therefore, these effects are insignificant (NMFS, 2007). The NMFS (2009a) found that marine mammals in the Beaufort Sea that show behavioral avoidance for drilling activities were especially unlikely to incur auditory impairment or other physical injuries (75 FR 25741).

Drilling rig lighting and rig presence are not identified as IPFs for sperm whales in lease sale EISs (MMS, 2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), or the NMFS (2007) Biological Opinion.

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a). Data concerning the frequency of vessel strikes are presented in a previous lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, the BSEE and BOEM issued NTL 2012-JOINT-G01, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When whales are sighted, vessel operators and crews are required to attempt to maintain a distance of 91 m (300 ft) or greater whenever possible. Vessel operators are required to reduce vessel speed to 10 knots or less, when safety permits, when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm whales.

NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales. With implementation of the mitigation measures in NTL 2012-JOINT-G01, NMFS concluded that the likelihood of collisions between vessels and sperm whales would be reduced to insignificant levels. NMFS concluded that the observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a potential threat and is not expected to result in any significant effect on migration, breathing, nursing, breeding, feeding, or sheltering to individuals, or have any consequences at the population level. With implementation of the vessel strike avoidance measures requirement to maintain a distance of 91 m (300 ft) from sperm whales, the NMFS concluded that the potential for harassment of sperm whales
would be reduced to discountable levels.

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) documented responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an altitude of 245 m (800 ft). A

r eaction to the initial pass of the aircraft was observed during 3 (12%) of 24 sightings. All three reactions consisted of a hasty dive and occurred at less than 360 m (1,180 ft) lateral distance from the aircraft.
Additional reactions were seen when aircraft circled certain whales to make further observations. Based on other studies of cetacean responses to sound, the authors concluded that the observed reactions to brief overflights by the aircraft were short-term and probably of no long-term biological significance.

While flying offshore in the Gulf of Mexico, helicop ters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In the event that a whale is seen during transit, the helicopter will not approach or circle the animals. Although responses are possible (Smultea et al., 2008), the NMFS (2007) and BOEM (2012d) concluded that this altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impacts are expected.Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), and by NMFS (2007). Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this EP, there are no unique site-specific issues with respect to spill impacts on these animals that were not analyzed in the previous
documents.

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will mitigate and lessen the potential for impacts on sperm whales. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and
weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (Marine Mammal Commission [MMC], 2011). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of sperm whales, no significant impacts would be expected.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals including sperm whales are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), and by NMFS (2007). For this EP, there are no unique site-specific issues with respect to spill impacts on these animals.

Impacts of oil spills on sperm whales can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2011). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat, disruption of social structure, changing prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2011). Ackleh et al. (2012) hypothesized that sperm whales may have temporarily relocated away from areas near the Macondo spill in 2010.

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to reduce the potential for striking or disturbing these animals.

C.3.2 West Indian Manatee (Endangered)

Most of the Gulf of Mexico manatee population is located in peninsular Florida (USFWS, 2001). Manatee sightings in Louisiana have increased as the species extends its presence farther west of Florida in thewarmer months (Wilson, 2003). A species description is presented in a previous lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS, 2001).

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect manatees, as the lease area is approximately 261 km (162 miles) from the nearest shoreline (Louisiana). As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on manatees.

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001). To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 2012-JOINT-G01, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. Compliance with this NTL will minimize the likelihood of vessel strikes, and no significant impacts on manatees are expected.

Helicopter traffic also has the potential to disturb manatees. Rathbun (1988) reported that manatees were disturbed more by helicopters than by fixed-wing aircraft; however, the helicopter was flown at relatively low altitudes of 20 to 160 m (66 to 525 ft). Helicopters used in support operations maintain a minimum altitude of 213 m (700 ft) while in transit offshore, 305 m (1,000 ft) over unpopulated areas or across coastlines, and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and park properties. In addition, guidelines and regulations specify that helicopters maintain an altitude of 305 m (1,000 ft) within 91 m (300 ft) of marine mammals (BOEM, 2012a,d). This mitigation measure will minimize the potential for disturbing manatees, and no significant impacts are expected.

Impacts of a Large Oil Spill (WCD)

In the event that manatees were exposed to oil, effects could include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2011). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey or contaminated vegetation; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat, disruption of social structure, changing prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2011).

In the event that a large spill reached coastal waters where manatees were present, the level of vessel and aircraft activity associated with spill response could disturb manatees and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected.

C.3.3 Endangered Mysticete Whales

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of

Mexico.Because of the rare occurrence of these whales in the Gulf of Mexico and the limited scope and duration of the project, it is highly unlikely that any endangered mysticete would come into contact with any project activities, either routine operations or accidents. NMFS did not include any of these mysticete whales as affected species in its Biological Opinion (NMFS, 2007). Potential impacts are analyzed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d), and those analyses are incorporated by reference. If any of these whales were present in the area, potential impacts would be the same as those discussed below in Section C.3.4

.
C.3.4 Non-Endangered Marine Mammals (Protected)

Excluding the seven endangered species that have been cited previously, there are 22 additional species of marine mammals that may be found in the Gulf of Mexico, including 2 species of mysticete whales, 2 species of sperm whales, 4 species of beaked whales, and 14 species of delphinids. All marine mammals are protected species under the MMPA. The most common nonendangered cetaceans in the deepwater environment are odontocetes such as the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin. A brief summary is presented below, and additional information on these groups is presented in a previous lease sale EIS (MMS, 2007b).

Mysticete whales . Two species of nonendangered mysticete whales are known from the Gulf of Mexico. The Bryde’s whale ( **Balaenoptera edeni** ) has been sighted most frequently along the 100-m (328-ft) isobath (Davis and Fargion, 1996; Davis et al., 2000). Most sightings have been made in the DeSoto Canyon region and off western Florida, although there have been some in the west-central portion of the northeastern Gulf. The minke whale ( **Balaenoptera acutorostrata** ) is considered rare in the Gulf of Mexico, with the only confirmed records coming from strandings (Würsig et al., 2000). Based on the available data, it is possible that Bryde’s whales could occur in the lease area.

Dwarf and pygmy sperm whales . At sea, it is difficult to differentiate dwarf sperm whales ( **Kogia sima** ) from pygmy sperm whales ( **Kogia breviceps** ), and sightings are often grouped together as **Kogia** spp. Both species have a worldwide distribution in temperate to tropical waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge and in deeper waters off the continental shelf (Mullin et al., 1991). Either species could occur in the lease area.

Beaked whales . Four species of beaked whales are known from the Gulf of Mexico: Blainville’s beaked whale ( **Mesoplodon densirostris** ), Cuvier’s beaked whale ( **Ziphius cavirostris** ), Sowerby’s beaked whale ( **Mesoplodon bidens** ), and Gervais’ beaked whale ( **Mesoplodon europaeus** ). Stranding records in the Gulf of Mexico suggest that Gervais’ beaked whale is the most common and Sowerby’s is extralimital. Due to the difficulties of at-sea identification, beaked whales in the Gulf of Mexico are identified either as Cuvier’s beaked whales or are grouped into an undifferentiated complex ( **Mesoplodon** spp. and **Ziphius** spp.). In the northern Gulf of Mexico, they are broadly distributed in water depths greater than 1,000 m (3,281 ft) over lower slope and abyssal landscapes (Davis et al., 2000). Any of these species could occur in
the lease area.

Delphinids . Fourteen species of delphinids are known from the Gulf of Mexico, including Atlantic spotted dolphin ( **Stenella frontalis** ), bottlenose dolphin ( **Tursiops truncatus** ), Clymene dolphin ( **Stenella clymene** ), false killer whale ( **Pseudorca crassidens** ), Fraser’s dolphin ( **Lagenodelphis hosei** ), killer whale ( **Orcinus**

**orca** ), melon-headed whale ( **Peponocephala electra** ), pantropical spotted dolphin ( **Stenella attenuata** ), pygmy killer whale ( **Feresa attenuata** ), short-finned pilot whale ( **Globicephala macrorhynchus** ), Risso’s dolphin ( **Grampus griseus** ), rough-toothed dolphin ( **Steno bredanensis** ), spinner dolphin ( **Stenella longirostris**  ), and striped dolphin ( **Stenella coeruleoalba** ). Any of these species could occur in the lease area. The most common nonendangered cetaceans in the deepwater environment are the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin.

The bottlenose dolphin ( **Tursiops truncatus** ) is a common inhabitant of the northern Gulf of Mexico, particularly within continental shelf waters. There are two ecotypes of bottlenose dolphins, a coastalform and an offshore form, which are genetically isolated from each other (Waring et al., 2012). The offshore form of the bottlenose dolphin may occur within the lease area. Inshore populations of coastal bottlenose dolphins in the northern Gulf of Mexico are separated into 37 geographically distinct population units, or stocks, for management purposes by the NMFS (Waring et al., 2012). NMFS (2013) has proposed to classify the Gulf of Mexico Northern Coastal Stock, Western Coastal Stock, and all 32 of the Bay, Sound, and Estuarine Stocks as strategic stocks. A “strategic” stock is defined by the MMPA as a
marine mammal stock:

• 1. for which the level of direct human-caused mortality exceeds the potential biological removal level;

• 2. that, based on the best available scientific information, is declining and is likely to be listed as a threatened species under the ESA within the foreseeable future; or

• 3. that is listed as a threatened or endangered species under the ESA, or is designated as depleted
under the MMPA.

The strategic stock designation in this case was based primarily on the occurrence of an “unusual mortality event” of unprecedented size and duration that has affected these stock areas. This unusual mortality event began in February 2010 and is ongoing. Carmichael et al. (2012) hypothesized that the unusual number of bottlenose dolphin strandings in the northern Gulf of Mexico during this time may have been associated with environmental perturbations including sustained cold weather and the Macondo spill in 2010 as well as large volumes of cold freshwater discharge in the early months of 2011.

IPFs potentially affecting nonendangered marine mammals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents–a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on marine mammals due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of marine mammals. Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on marine mammals.

Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most odontocetes (toothed whales and dolphins) use higher-frequency sounds than those produced by OCS drilling activities (Richardson et al., 1995). Noise intensity associated with drilling is relatively weak, and the noise exposure of an individual animal would be transient. Stronger noise levels will occur during thruster use in dynamic positioning. Thruster noise impacts would be expected at greater distances than vessel noise alone (LGL Ecological Research Associates, Ltd., 2006) but are dependent on variables relating to thruster type and usage. It is expected that marine mammals within or near the lease area would be able to detect the presence of the drilling rig and avoid exposure to higher energy sounds, particularly within an open ocean environment.

Some odontocetes have shown increased feeding activity around lighted platforms at night (Todd et al., 2009). Even temporary drill rigs present an attraction to pelagic food sources that may attract cetaceans (and sea turtles). Therefore, prey congregation could pose an attraction to protected species that exposes them to higher levels or longer durations of noise that might otherwise be avoided.

There are other OCS facilities and activities near the lease area, and the region as a whole has a large number of similar sources. Due to the limited scope and short duration of drilling activities, this project would represent a small temporary contribution to the overall noise regime, and any short-term impacts are not expected to be biologically significant to marine mammal populations.

Drilling rig lighting and rig presence are not identified as IPFs for marine mammals in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d).Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals, and there is also a risk of vessel strikes. Data concerning the frequency of vessel strikes are presented in a previous lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 2012-JOINT-G01, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. Vessel operators and crews are required to attempt to maintain a distance of 91 m (300 ft) or greater when whales are sighted and 45 m (150 ft) when small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels must attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt changes in direction until the cetacean has left the area. Vessel operators are required to reduce vessel speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel, when safety permits. Compliance with NTL 2012-JOINT-G01 will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing marine mammals, and therefore no significant impacts are expected.

Aircraft traffic also has the potential to disturb marine mammals (Würsig et al., 1998). However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In addition, guidelines and regulations specify that helicopters maintain an altitude of 305 m (1,000 ft) within 91 m (300 ft) of marine mammals (BOEM, 2012a,d). Maintaining this altitude will minimize the potential for disturbing marine mammals, and no significant impacts are expected (BOEM, 2012a,d).

Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b), and oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For this EP, there are no unique site-specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP is expected to lessen the potential for impacts on marine mammals. EP Section 9 provides detail on spill response measures, along with a summary of those measures in this EIA. Given the open ocean location of the lease area, the limited duration of a small spill, and response efforts, it is expected that any impacts would be brief and
minimal.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and
weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 2011). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of marine mammals, no significant impacts would be expected.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b). For this EP, there are no unique site-specific issues. Impacts of oil spills on marine mammals can includedirect impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2011). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat, disruption of social structure, changing prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2011).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb marine mammals and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected.

C.3.5 Sea Turtles (Endangered/Threatened)

Five species of endangered or threatened sea turtles may be found near the lease area. Leatherback ( **Dermochelys coriacea** ), Kemp's ridley ( **Lepidochelys kempii** ), and hawksbill ( **Eretmochelys imbricata** ) turtles are endangered. The loggerhead turtle ( **Caretta caretta** ) is currently a threatened species; however, in March 2010, NMFS and USFWS proposed to list the Northwest Atlantic Ocean population of loggerhead turtles as endangered (75 FR 12598). The green turtle ( **Chelonia mydas** ) is listed as threatened, except for the Florida and Pacific coast of Mexico breeding populations, which are listed as endangered. Species descriptions are presented in MMS (2007b).

The extent and scope of the Macondo spill represents new information not assessed in the existing ESA Section 7 consultation. As a result of this new information, BOEMRE reinitiated ESA Section 7 consultation with NMFS and the USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on 24 September 2010, and the USFWS responded with a letter to BOEMRE on 27 September 2010. However, NMFS and the USFWS have placed the consultation process on hold pending the results of the NRDA post-Macondo spill data review, which has yet to be released. The existing consultation currently remains in effect (BOEM, 2012b).

BOEMRE (2011a) and BOEM (2012b) reexamined the impacts analyses presented in MMS (2007b, 2008) for the five sea turtle species that inhabit the Gulf of Mexico based on additional information and in consideration of the Macondo spill. No new information was found that would alter the potential impacts on sea turtles described in previous EISs. In most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick will result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles.

Leatherbacks and loggerheads are the most likely species to be present near the lease area as adults. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and nearshore species, unlikely to occur near the lease area as adults. Hatchlings or juveniles of any of the sea turtle species may be present in deepwater areas, including the lease area, where they may be associated with **Sargassum** and other
flotsam.

Sea turtle nesting in the northern Gulf of Mexico can be summarized by species as follows:

• Loggerhead turtles – Loggerheads nest in significant numbers along the Florida Panhandle and, to a lesser extent, from Texas through Alabama (MMS, 2007b). The nearest significant nesting area of loggerhead turtles is found in Louisiana, on beaches within the Breton NWR;

• Green and leatherback turtles – Green and leatherback turtles infrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 2012);• Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach, Tamaulipas, Mexico (NMFS et al., 2011). Kemp’s ridley turtles typically do not nest anywhere near the project area, although there have been occasional reports of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles – Hawksbills typically do not nest anywhere near the project area.

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents–a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on sea turtles due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges. Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on sea turtles.

Impacts of Drilling Rig Presence, Noise, and Lights

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include behavioral disruption and temporary or permanent displacement from the area near the sound source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures (Lohoefener et al., 1990) and thus may be more susceptible to impacts from sounds produced during routine operations. Helicopters and service vessels may also affect sea turtles due to machinery noise and/or visual disturbances. The most likely impacts would be short-term behavioral changes such as diving and evasive swimming, disruption of activities, or departure from the area. Due to the limited scope and short duration of drilling activities, these short-term impacts are not expected to be biologically significant to sea turtle populations.

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 1997; Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). The NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are insignificant.

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sea turtles, and there is also a risk of vessel strikes. Data show that vessel traffic is one cause of sea turtle mortality in the Gulf of Mexico (Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in clear weather, they can be difficult to spot from a moving vessel when resting below the water surface, during nighttime, or during periods ofinclement weather. To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 2012-JOINTG01, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for sea turtles and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When sea turtles are sighted, vessel operators and crews are required to attempt to maintain a distance of 45 m (150 ft) or greater whenever possible. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007).

Helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are expected.

Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the NMFS Biological Opinion (NMFS, 2007). For this EP, there are no unique site-specific issues with respect to spill impacts on these animals.The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP is expected to minimize potential impacts on sea turtles. EP Section 9 provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and
weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMS, 2007b; NMFS, 2010b; BOEM, 2012b,d). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, no significant impacts would be expected.

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches, as the lease area is 261 km (162 miles) from the nearest shoreline (Louisiana). As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of a Large Oil Spill (WCD)

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes and smoke (e.g., from **in situ** burning of oil); ingestion of oil (and dispersants) directly or via contaminated food; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat, disruption of social structure, changing food availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP is expected to minimize the potential for these types of impacts on sea turtles. EP Section 9 provides detail on spill response measures.

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) suggest that sea turtles show no avoidance behavior when they encounter an oil slick, and any sea turtle in an affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them at risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface over time, which may result in repeated exposure to volatile vapors and oiling (NMFS, 2007).

Spilled oil reaching sea turtle nesting beaches could have effects on nesting sea turtles and egg development (NMFS, 2007). An oiled beach could affect nest site selection or result in no nesting at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings are subject to the same types of oil spill exposure hazards as adults. Hatchlings that contact oil residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaired movement and normal bodily functions (NMFS, 2007).In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sea turtles and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected.

C.3.6 Piping Plover (Threatened)

The Piping Plover ( **Charadrius melodus** ) is a migratory shorebird that overwinters along the southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result of hunting, habitat loss and modification, predation, and disease (USFWS, 2003). Critical overwintering habitat has been designated, including beaches in Texas, Louisiana, Mississippi, Alabama, and Florida ( Figure 3 ). Piping Plovers inhabit coastal sandy beaches and mudflats, feeding by probing for invertebrates at or just below the surface. They use beaches adjacent to foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in a previous lease sale EIS (MMS, 2007b).

A large oil spill (WCD) is the only IPF potentially affecting Piping Plovers. There are no IPFs associated with routine project activities that could affect these birds. A small fuel spill in the lease area would be unlikely to affect Piping Plovers because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in Section A.9.2 ).Figure 3. Location of selected environmental features in relation to the lease area.Impacts of a Large Oil Spill (WCD)

The lease area is 262 km (163 miles) from the nearest shorelines inhabited by Piping Plovers ( Figure 3 ). The revised OSRA results (BOEMRE, 2011a; BOEM, 2012b) summarized in Section A.9.3 ( Table 3 ) predict that during the spring there is a 4% probability that an oil spill from the lease area would reach a shoreline designated as critical habitat for the Piping Plover within 10 days. Plovers could physically oil themselves while foraging on oiled shores or secondarily contaminate themselves through ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers congregate and feed along tidally exposed banks and shorelines, following the tide out and foraging at the water’s edge. It is possible that some deaths of Piping Plovers could occur, especially if spills occur during winter months when plovers are most common along the coastal Gulf or if spills contacted critical habitat. Impacts could also occur from vehicular traffic on beaches and other activities associated with spill cleanup. ExxonMobil has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in
the OSRP.

C.3.7 Whooping Crane (Endangered)

The Whooping Crane ( **Grus americana** ) is an omnivorous wading bird and an endangered species. There are three wild populations in North America (Whooping Crane Eastern Partnership, 2010). One population winters along the Texas coast at Aransas NWR and summers at Wood Buffalo National Park in Canada; this population represents the majority of the world’s population of free-ranging Whooping Cranes and reached a record population of 270 at Aransas NWR in December 2008 (Whooping Crane Eastern Partnership, 2010). A nonmigrating population has been reintroduced in central Florida, and another reintroduced population summers in Wisconsin and migrates to the southeastern U.S. for the winter. Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fields (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for the species. A species description is presented in lease sale EISs (MMS, 2007b; BOEM, 2012a). A large oil spill (WCD) is the only IPF potentially affecting Whooping Cranes. A small fuel spill in the lease area would also be unlikely to affect Whooping Cranes, due to the distance from Aransas NWR. As explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of a Large Oil Spill (WCD)

A large oil spill is unlikely to affect Whooping Cranes as the lease area is approximately 563 km (350 miles) from its critical habitat designated in the Aransas NWR. The revised OSRA modeling (BOEM, 2012b) predicts that there is a 3% or less probability that an oil spill originating in the lease area would reach the Aransas NWR within 30 days and a 17% probability of oil reaching that area in 120 days.

In the event of oil exposure, Whooping Cranes could physically oil themselves while foraging in oiled areas or secondarily contaminate themselves through ingestion of contaminated shellfish, frogs, and fishes. It is possible that some Whooping Crane deaths could occur. In the event of a spill, ExxonMobil would work with the applicable State and Federal agencies to prevent impacts from a spill.

C.3.8 Gulf Sturgeon (Threatened)

The Gulf sturgeon ( **Acipenser oxyrinchus desotoi** ) is a threatened fish species that inhabits major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida (Barkuloo, 1988; Wakeford, 2001). An anadromous fish that migrates from the sea upstream into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner shelf waters from theMississippi River to the Suwannee River, Florida. Populations have been depleted or even extirpated throughout this range by fishing, shoreline development, dam construction, water quality changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatened species in 1991. The best known populations occur in the Apalachicola and Suwannee Rivers in Florida (Carr, 1996; Sulak and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 2000), and the Pearl River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the Gulf extends from Lake Borgne, Louisiana (St. Bernard Parish) to Suwannee Sound, Florida (Levy County) (NMFS, 2010b) ( Figure 3 ). A species description is presented in a lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS and Gulf States Marine Fisheries Commission, 1995).

A large oil spill (WCD) is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect Gulf sturgeon because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in Section A.9.2 ).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on Gulf sturgeon are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and by NMFS (2007). For this EP, there are no unique site-specific issues with respect to this species.

The lease area is approximately 378 km (235 miles) from the nearest Gulf sturgeon critical habitat. The revised OSRA modeling (BOEM, 2012b) predicts that a spill in the lease area has 1% or less probability of contacting any coastal areas inhabited by Gulf sturgeon within 30 or 120 days.

In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills. Based on the life history of this species, subadult and adult Gulf sturgeon would be most vulnerable to an estuarine or marine oil spill, and would be vulnerable only from 1 September through 30 April when this species is foraging in estuarine and shallow marine habitats (NMFS, 2007).

C.3.9 Smalltooth Sawfish (Endangered)

Smalltooth sawfish ( **Pristis pectinata** ) are found in the tropical and subtropical Atlantic Ocean. In the Western Atlantic they have historically ranged from New York to Brazil, including the Gulf of Mexico and Caribbean Sea. This sawfish primarily occurs in estuarine and coastal habitats such as bays, lagoons, and rivers. The smalltooth sawfish was listed as endangered under the ESA on 1 April 2003. Its critical habitat consists of two units: the Charlotte Harbor Estuary Unit, which comprises approximately 89,621 ha (221,459 ac) of coastal habitat; and the Ten Thousand Islands/Everglades Unit, which comprises approximately 250,506 ha (619,013 ac) of coastal habitat. The two units are located along the southwestern coast of Florida between Charlotte Harbor and Florida Bay.

A large oil spill (WCD) is the only IPF potentially affecting smalltooth sawfish. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect smalltooth sawfish because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on smalltooth sawfish are similar to those discussed for other coastal and estuarine species in lease sale EISs (MMS, 2007b; BOEM, 2012a) and by the NMFS (2007) in its Biological Opinion. For this EP, there are no unique site-specific issues with respect to smalltooth sawfish.

In the event of oil reaching smalltooth sawfish habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills.C.3.10 Beach Mice (Endangered)

Four subspecies of endangered beach mouse ( **Peromyscus polionotus** ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctawhatchee, Perdido Key, and St. Andrew beach mice. Critical habitat has been designated for all four subspecies; Figure 3 shows the critical habitat combined for all four subspecies. Species descriptions are provided in a previous lease sale EIS (MMS, 2007b).

A large oil spill (WCD) is the only IPF potentially affecting beach mice. There are no IPFs associated with routine project activities that could affect these animals due to the distance from shore and the lack of any onshore support activities near their habitat. A small fuel spill in the lease area would not affect beach mice because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on beach mice are discussed in lease sale EISs (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012a). For this EP, there are no unique site-specific issues with respect to these species that were not analyzed in those documents.

The lease area is about 493 km (306 miles) northeast from the nearest beach mouse critical habitat. The revised OSRA modeling summarized in Section A.9.3 predicts that a spill in the lease area has a 1% or less probability of reaching either the Alabama or Florida shorelines inhabited by beach mice within 120 days.

In the event of oil contacting these beaches, beach mice could experience several types of direct and indirect impacts. Contact with spilled oil could cause skin and eye irritation and subsequent infection; matting of fur; irritation of sweat glands, ear tissues, and throat tissues; disruption of sight and hearing; asphyxiation from inhalation of fumes; and toxicity from ingestion of oil and contaminated food. Indirect impacts could include reduction of food supply, destruction of habitat, and fouling of nests. Impacts could also occur from vehicular traffic and other activities associated with spill cleanup. However, any such impacts are unlikely due to the distance from shore and response actions that would occur in the event of a spill.

C.3.11 Elkhorn Coral (Endangered)

Elkhorn coral ( **Acropora palmata** ) is found primarily in shallow waters with temperatures ranging between 26°C and 30°C (79°F and 86°F) and significant water movement. Elkhorn coral was once one of the most abundant coral species in waters ranging from 1 to 5 m (3.3 to 16 ft) deep in tropical and subtropical waters. In the northern Gulf of Mexico, elkhorn coral has been found within the coral cap region of the Flower Garden Banks National Marine Sanctuary (Flower Garden Banks National Marine Sanctuary, 2011).

There are no IPFs associated with routine project activities that could affect this species in the northern Gulf of Mexico. A small fuel spill would not affect elkhorn coral colonies because the oil would float and dissipate on the sea surface. A WCD would be unlikely to affect the coral cap region of the Flower Garden Banks because of the water depth of the area. Although subsurface plumes were reported following the Macondo spill, these plumes resulted from the use of subsea dispersants at the seafloor.

C.4 Coastal and Marine Birds

C.4.1 Marine Birds

Marine birds include seabirds and other species that may occur in the pelagic environment of the project area (Clapp et al., 1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Seabirds spend much of their lives offshore over the open ocean, except during breeding season when they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and shorebirds may occasionally be present overopen ocean areas. No endangered or threatened bird species are likely to occur at the project area due to the distance from shore. For a discussion of shorebirds and coastal nesting birds, see Section C.4.2

.

Seabirds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. Hess and Ribic (2000) reported that terns, storm-petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater area. From these surveys, four ecological categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants (shearwaters, storm petrels, boobies), summer residents that breed in the Gulf (Sooty Tern, Least Tern, Sandwich Tern, Magnificent Frigatebird), winter residents (gannets, gulls, jaegers), and permanent resident species (Laughing Gulls, Royal Terns, Bridled Terns) (Hess and Ribic, 2000). The GulfCet II study did not estimate bird densities; however, Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2

.

Relationships with hydrographic features were found for several seabird species, possibly due to effects of hydrography on nutrient levels and productivity of surface waters where birds forage (Powers, 1987). Common seabird species include Wilson’s Storm-Petrel ( **Oceanites oceanicus** ), Magnificent Frigatebird ( **Fregata magnificens** ), Northern Gannet ( **Morus bassanus** ), Masked Booby ( **Sula dactylatra** ), Brown Booby ( **Sula leucogaster** ), Cory’s Shearwater ( **Calonectris diomedea** ), Greater Shearwater ( **Puffinus gravis** ), and Audubon’s Shearwater ( **Puffinus lherminieri** ). Seabirds are distributed Gulf-wide and are not specifically
associated with the lease area.

Trans-Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be present in the lease area. Migrant birds may use offshore structures and rigs for resting, feeding, or as temporary shelter from inclement weather (Russell, 2005). Some birds may be attracted to offshore structures because of the lights and the fish populations that aggregate around these structures.

IPFs potentially affecting marine and pelagic birds include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents–a small fuel spill and a large oil spill (WCD). Effluent discharges permitted under the NPDES permit are likely to have negligible impacts on the birds
d ue to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these animals. Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on birds.

Impacts of Drilling Rig Presence, Noise, and Lights

Birds that frequent rigs may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispersion. Birds migrating over water have been known to strike offshore structures, resulting in death or injury (Wiese et al., 2001; Russell, 2005). Mortality of migrant birds at tall towers and other land-based structures has been reviewed extensively, and the mechanisms involved in rig collisions appear to be similar. In some cases, migrants simply do not see a part of the rig until it is too late. In other cases, navigation may be disrupted by noise (Russell, 2005). On the other hand, offshore structures are suitable stopover habitats for most trans-Gulf migrant species, and most of the migrants that stop over on rigs probably benefit from their stay, particularly in spring (Russell, 2005). Due to the limited scope and short duration of drilling activities described in this EP, any impacts on populations of either seabirds or trans-Gulf migrant birds are not expected to be significant.

A study in the North Sea indicated that rig lighting causes circling behavior in various birds, especially on cloudy nights; apparently the birds’ geomagnetic compasses are upset by the red part of the spectrum from the lights currently in use (Nederlandse Aardolie Maatschappij, 2007). The numbers varied greatly, from none at all to some tens of thousands of birds per night per rig, with an apparent effect radius of up to 5 km (3 miles). Poot et al. (2008) found the magnetic compass of migratory birds to be wavelength-dependent. Migratory birds require light from the blue-green part of the spectrum for magnetic compass orientation, whereas red light (visible long-wavelength) disrupts their magnetic orientation. They designed a field study to test if and how changing light color influenced migrating birds under field conditions. During field studies they found that nocturnally migrating birds were disorientedand attracted by red and white light (containing visible long-wavelength radiation), whereas they were clearly less disoriented by blue and green light (containing less or no visible long-wavelength radiation) (Poot et al., 2008).

The OSPAR workshop (OSPAR Commission, 2012) noted that this circling increases the risk of collisions leading to traumas and deaths and may interrupt their migration. A study in the Gulf of Mexico also noted the phenomenon but did not recommend mitigation (Russell, 2005). Factors to consider in evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and foggy days in
the Gulf of Mexico versus the North Sea.

Overall, potential negative impacts to birds from drilling rig lighting, potential collisions, or other adverse effects are highly localized, relatively short-term and temporary in nature, and may be expected to affect only individual birds during migration periods. Therefore, these potential impacts are not expected to affect birds at the population or species level and are not significant (BOEM, 2012a).

Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open, offshore waters. It is likely that individual birds would experience, at most, only short-term behavioral disruption, and the impact would not be significant.

Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will reduce the potential for impacts on marine and pelagic birds. EP Section 9 provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and
weather conditions.

Birds exposed to oil on the sea surface could experience direct physical and physiological effects including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of VOCs. Due to the limited areal extent and short duration of water quality impacts from a small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in prey abundance are unlikely. Due to the low densities of birds in open ocean areas, the small area affected, and the brief duration of the surface slick, no significant impacts on pelagic birds would be expected.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine and pelagic birds are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012 a,b) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to spill impacts on these animals.BOEM has reexamined the analyses for coastal and marine birds presented in MMS (2007b, 2008) and determined that no new information was found that would alter the potential impacts on marine and pelagic birds (BOEMRE, 2011a; BOEM, 2012b).

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) reported that terns, storm-petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater Gulf of Mexico (>200 m [>656 ft]). Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2 . The number of pelagic birds that could be affected in open, offshore waters would depend on the extent and persistence of the oil slick.

The recent Macondo spill provides relevant information about the species of pelagic birds that may be affected in the event of a large oil spill. Birds that have been treated for oiling include several pelagic species such as the Northern Gannet, Magnificent Frigatebird, and Masked Booby (USFWS, 2011). The Northern Gannet is among the species with the largest numbers of birds affected by the spill.

C.4.2 Shorebirds and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plover and Whooping Crane) have been discussed previously in Section C.3 . Various species of non-endangered birds are also found along the northern Gulf Coast, including diving birds, shorebirds, marsh birds, wading birds, and waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. Species that nest on beaches, flats, dunes, bars, barrier islands, and similar coastal and nearshore habitats include the Sandwich Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull-Billed Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in lease sale EISs (MMS, 2007b; BOEM, 2012a).

The Brown Pelican ( **Pelecanus occidentalis** ) was delisted from Federal endangered status in 2009 (USFWS, 2010c). However, this species remains listed as endangered by the State of Louisiana (Louisiana Department of Wildlife and Fisheries, 2013), is listed as a species of greatest conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries and Parks, 2011), and is listed as a species of special concern by the State of Florida (Florida Fish and Wildlife Conservation Commission, 2011). Brown Pelicans inhabit coastal habitats and forage within both coastal waters and waters of the inner continental shelf. Aerial and shipboard surveys, including GulfCet and GulfCet II, indicate that Brown Pelicans do not occur in deep offshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population of Brown Pelicans lives in the northern Gulf Coast, generally nesting on protected islands (USFWS, 2010b).

The Southern Bald Eagle ( **Haliaeetus leucocephalus** ) was delisted from its threatened status in the lower 48 states on 28 June 2007. The Bald Eagle is a terrestrial raptor widely distributed across the southern U.S., including coastal habitats along the Gulf of Mexico. The Gulf Coast is inhabited by both wintering migrant and resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 1992).

IPFs potentially affecting shorebirds and coastal nesting birds include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect shorebirds or coastal nesting birds, as the lease area is 261 km (162 miles) from the nearest shoreline. As explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on shorebirds.

Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas near Port Fourchon, Louisiana, where shorebirds and coastal nesting birds may be found. These activities could periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may support feeding, resting, or breeding birds).Vessel traffic may disturb some foraging and resting birds. Flushing distances vary between species and between individuals (Rodgers and Schwikert, 2002). The disturbances will be limited to flushing birds away from vessel pathways; known distances are from 20 to 49 m (65 to 160 ft) for personal watercraft and 23 to 58 m (75 to 190 ft) for an outboard-powered boat (Rodgers and Schwikert, 2002). Flushing distances may be similar or less for the support vessels to be used for ExxonMobil’s project, and some species such as gulls are attracted to boats. Support vessels will not approach nesting or breeding areas on the shoreline, so disturbances to nesting birds, eggs, and chicks is not expected. Vessel operators will use designated navigation channels and comply with posted speed and wake restrictions while transiting sensitive inland waterways. Due to the limited scope and short duration of drilling activities, any short-term impacts are not expected to be significant to coastal bird populations.

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly dependent on the type of aircraft, the bird species, the activities that animals were previously engaged in, and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to cause the most intense responses over other human disturbances (Bélanger and Bédard, 1989). The Federal Aviation Administration recommends (Advisory Circular No. 91-36D) that pilots maintain a minimum altitude of 610 m (2,000 ft) when flying over noise-sensitive areas such as parks, forest, primitive areas, wilderness areas, National Seashores, or National Wildlife Refuges, and maintain flight paths to reduce aircraft noise in these noise-sensitive areas. The altitude minimum is greater than the distance (slant range) at which aircraft overflights have been reported to cause behavioral effects on most species of birds studied by Efroymson et al. (2000). It is assumed that adherence to these guidelines would reduce potential behavioral disturbances (such as temporary displacement or avoidance behavior) of individual birds in coastal and inshore areas. The potential impacts are not expected to be significant to bird populations or species in the project area.

Impacts of Large Oil Spill (WCD)

Data from the Macondo spill provide additional information about the species of coastal birds that may be affected in the event of a catastrophic spill of a similar nature and duration. This information supplements the analysis presented in the lease sale EIS (MMS, 2007b). According to USFWS (2010d) and based on the latest reports, about 5,000 dead birds have been collected since the spill began, and about 1,900 of the dead animals were visibly oiled. In addition, over 2,000 oiled birds have been collected alive and about 1,200 released (NMFS, 2010c). According to the USFWS (2011), bird species that have 

### been treated for oiling include the following:

### • Brown Pelican

• White Pelican

• Masked Booby

• Magnificent Frigatebird

• Laughing Gull

• Herring Gull

• Northern Gannet

• Black Crowned Night Heron

• Tri-colored Heron

• Green Heron

• Cattle Egret

• Snowy Egret

• Reddish Egret

• Least Bittern

• Common Tern

• Royal Tern

• Caspian Tern • Sandwich Tern

• Forster’s Tern

• Black Tern

• Gull-billed Tern

• Least Tern

• Black Skimmer

• Black Oystercatcher

• White Ibis

• Roseate Spoonbill

• Willet

• Sanderling

• Dunlin

• Semipalmated Sandpiper

• Killdeer

• King Rail

• Clapper Rail

• Virginia Rail

According to the USFWS (2010d), species with the largest numbers of dead oiled birds were Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, unidentified Gull, and unidentified Tern. There are no reports of Bald Eagle oiling.

Although the Macondo spill had direct and indirect impacts to coastal and marine birds, it is premature to conclude impacts over a long period (BOEM, 2012b). Modeling of Macondo spill-related bird impacts is underway by NRDA, but results have not yet been released. Antonio et al. (2011) modeled bird mortality from the Macondo spill showing cumulative carcass numbers and mortality rate increasing exponentially from the start of the Macondo spill until the mortality rate began to decline after the 97th day of the spill. Note that the collected animals would be a small subset of the total number of impacted birds, and therefore the collected animals would represent an underestimated measure of the overall impact of the Macondo event (BOEM, 2012b).

Coastal birds can be exposed to oil as they float on the water surface, dive during foraging, or wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which could lead to drowning (USFWS, 2010e). Oil interferes with the water repellency of feathers and can cause hypothermia in the right conditions. As birds groom themselves, they can ingest and inhale the oil on their bodies. Scavengers such as Bald Eagles and gulls can be exposed to oil by feeding on carcasses of contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, liver, and kidney damage, which can lead to death. Bird eggs may be damaged if an oiled adult sits on the

nest.

As noted above, the Brown Pelican was recently removed from the Federal endangered species list. Over 300 dead Brown Pelicans were collected in the Gulf following the Macondo spill, (USFWS, 2010d). These data indicate that Brown Pelicans may be particularly at risk of oiling in the event of a catastrophic spill reaching coastal waters. Issues for Brown Pelicans include direct contact with oil, disturbance by cleanup activities, and long-term habitat contamination.C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater environment of the northern Gulf of Mexico. The biological oceanography of the region is dominated by the influence of the Loop Current, whose surface waters are among the most oligotrophic in the world’s oceans. Superimposed on this low-productivity condition are productive "hot spots" associated with entrainment of nutrient-rich Mississippi River water and mesoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an important role in determining biogeographic patterns and controlling primary productivity in the northern Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the planktonic community for various lengths of time (10 to 100 days, depending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents–a small fuel spill and a large oil spill (WCD).

Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a fish-attracting device (FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994; MMS, 2000, 2007b, 2008). This FAD effect could possibly enhance the feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, impacts on fish populations, whether beneficial or adverse, are considered minor.

Impacts of Effluent Discharges

Treated sanitary and domestic wastes may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, organic matter, and chlorine, but should be diluted rapidly to undetectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Deck drainage may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. Deck drainage from contaminated areas will be passed through an oil-and-water separator prior to release, and discharges will be monitored for visible sheen. The discharges may have slightly elevated levels of hydrocarbons but should be diluted rapidly to undetectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water, are expected to be diluted rapidly and have little or no impact on water column biota.

Impacts of Water Intakes

Seawater will be drawn from the ocean for once-through, non-contact cooling of machinery on the drillship. The drillship considered for use for activities described in this EP is a "new" facility as defined by the NPDES permit and therefore will comply with the cooling water intake regulations for Phase III facilities under Section 316(b) of the Clean Water Act.The intake of seawater for cooling water will entrain plankton. The low intake velocity should allow most strong-swimming juvenile fishes and smaller adults to escape entrainment or impingement. However, drifting plankton would not be able to escape entrainment with the exception of a few fast-swimming larvae of certain taxonomic groups. Those organisms entrained may be stressed or killed, primarily through changes in water temperature during the route from cooling intake structure to discharge structure and mechanical damage (turbulence in pumps and condensers). Due to the limited scope and short duration of drilling activities, any short-term impacts of entrainment are not expected to be biologically significant to plankton or ichthyoplankton populations.

Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resources are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to spill impacts.

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will mitigate the potential for impacts on pelagic communities, including ichthyoplankton. EP Section 9 provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and
weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, and nekton. Due to the limited areal extent and short duration of water quality impacts, a small fuel spill would be unlikely to produce detectable impacts on pelagic communities.

Impacts of a Large Oil Spill (WCD)

A large oil spill could affect water column biota including phytoplankton, zooplankton, ichthyoplankton, and nekton. A large spill that persisted for weeks or months would be more likely to affect these communities. While adult and juvenile fishes may actively avoid a large spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larvae of fishes are especially vulnerable to oiling because they inhabit the upper layers of the water column, and they will die if exposed to certain toxic fractions of spilled oil. Impacts potentially would be greater if local-scale currents retained planktonic larval assemblages (and the floating oil slick) within the same water mass.

C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for spawning, breeding, feeding, and growth to maturity. Under the Magnuson-Stevens Fishery Conservation and Management Act, as amended, Federal agencies are required to consult on activities that may adversely affect EFH designated in Fishery Management Plans developed by the regional Fishery Management
Councils.

The BOEM (2012b) has reexamined the analysis for fish resources and EFH presented in lease EISs (MMS, 2007a,b), in consideration of the Macondo event. No substantial new information was found that would alter the impact conclusions for fish resources and EFH presented in MMS (2007a,b).The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Management Plans for corals and coral reefs, shrimps, stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. In 2005, the EFH for these managed species was redefined in Generic Amendment No. 3 to the various Fishery Management Plans (GMFMC, 2005). The EFH for most of these GMFMC-managed species is on the continental shelf in waters shallower than 183 m (600 ft). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef fishes, and shrimps. EFH for corals and coral reefs includes some shelf-edge topographic features on the Texas-Louisiana OCS, the nearest of which are located approximately 132 km (82 miles) north-northwest of the lease area along the shelf edge south of

Louisiana.

Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group for which EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, swordfishes, billfishes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near the lease area include the following species and life stages (NMFS, 2009b):

• Albacore tuna (adults)

• Atlantic bluefin tuna (spawn, eggs, larvae, adults)

• Bigeye tuna (adults)

• Bigeye thresher shark (all)

• Blue marlin (juveniles, adults)

• Longbill spearfish (juveniles, adults) • Longfin mako shark (all)

• Oceanic whitetip shark (all)

• Skipjack tuna (spawn, adults)

• Swordfish (larvae, juveniles, adults)

• White marlin (juveniles, adults)

• Yellowfin tuna (spawn, juveniles, adults)

Recent research indicates the central and western Gulf of Mexico may be important spawning habitat for Atlantic bluefin tuna, and NMFS (2009b) has designated a Habitat Area of Particular Concern (HAPC) for this species. The HAPC covers much of the deepwater Gulf of Mexico, including the lease area ( Figure 3 ). The areal extent of the HAPC is approximately 300,000 km 2 (15,000 mi 2 ). The prevailing assumption is that Atlantic bluefin tuna follow an annual cycle of foraging in June through March off the eastern U.S. and Canadian coasts, followed by migration to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009b).

On 27 May 2011, after an extensive scientific review, NOAA announced that Atlantic bluefin tuna currently do not warrant species protection under the ESA. However, NOAA did classify the bluefin tuna as a species of concern, effectively placing bluefin tuna on a watch list as the agency awaits new data on the impact of a stricter international management regimen.

A new amendment to the original EFH Generic Amendment was finalized in 2005 (GMFMC, 2005). One of the most significant proposed changes in this amendment reduced the extent of EFH relative to the 1998 Generic Amendment by removing the EFH description and identification from waters between 100 fathoms and the seaward limit of the Exclusive Economic Zone (EEZ). The Highly Migratory Species Fisheries Management Plan was amended in 2009 to update EFH and HAPC to include the bluefin tuna spawning area (NMFS, 2009b).

There are current NTLs (2009-G39 and 2009-G40) that provide guidance and clarification of the regulations with respect to biologically sensitive underwater features and areas and benthic communities that are considered EFH (MMS, 2009a,b). A new EFH consultation has been initiated between BOEM’s Gulf of Mexico Region and NOAA’s Southeastern Region. Some EFH requirements may change with the new agreement. Until the new agreement is in place, the 1999 Programmatic Consultation with the elements described above will be followed (BOEMRE, 2011a; BOEM, 2012b).

Other HAPCs have been identified by the GMFMC (2005). These include the Florida Middle Grounds, Madison-Swanson Marine Reserve, Tortugas North and South Ecological Reserves, Pulley Ridge, andseveral individual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 ). The nearest HAPC is Jakkula Bank, located approximately 150 km (93 miles) north-northwest of the lease area.

IPFs potentially affecting EFH include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents–a small fuel spill and a large oil spill (WCD).

Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as an FAD. In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994; MMS, 2000, 2007b, 2008). This FAD effect would possibly enhance feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, any impacts on EFH for highly migratory pelagic fishes are considered

minor.

Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling muds and cuttings, treated sanitary and domestic wastes, deck drainage, and miscellaneous discharges such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water. Impacts on water quality have been discussed previously. No significant impacts on EFH for highly migratory pelagic fishes are expected from these discharges.

Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, including fish eggs and larvae (ichthyoplankton). Due to the limited scope and short duration of drilling activities, any short-term impacts on EFH for highly migratory pelagic fishes are not expected to be biologically significant.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will help diminish the potential for impacts on EFH. EP Section 9 provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Potential spill impacts on EFH are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to spill impacts.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and
weather conditions.

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, including tunas, swordfishes, billfishes, and sharks. These species occur as transients in the lease area. A spill would also produce short-term impact on water quality in the HAPC for spawning bluefin tuna, which covers much of the deepwater Gulf of Mexico. The areal extent of the affected area would represent a negligible portion
of the HAPC.A small fuel spill would not affect EFH for corals and coral reefs, the nearest of which is the topographic features located approximately 132 km (82 miles) from the lease area along the shelf edge south of Louisiana. A small fuel spill would float and dissipate on the sea surface and would not contact these
features.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on EFH are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to EFH.

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the water surface and potentially in the subsurface as well. Given the extent of EFH designations in the Gulf of Mexico (GMFMC, 2005; NMFS, 2009b), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species including shrimps, stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse impacts on water quality and water column biota including phytoplankton, zooplankton, and nekton. In coastal waters, sediments could be contaminated and result in persistent degradation of the seafloor habitat for managed demersal fish and shellfish species.

The lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009b). A large spill could temporarily degrade the HAPC due to increased hydrocarbon concentrations in the water column, with the potential for lethal or sublethal impacts on spawning tuna. Potential impacts would depend in part on the timing of a spill, as this species migrates to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009b).

The topographic features located 132 km (82 miles) north-northwest of the lease area are designated as EFH under the corals and coral reefs management plan. An accidental spill would be unlikely to affect this area, since a surface slick would not reach these features because of their depth.

C.6 Archaeological Resources

C.6.1 Shipwreck Sites

The BOEM (2012b) reexamined the analyses for archaeological resources presented in MMS (2007b, 2008), based on additional information available since the publication of these two documents and in consideration of the Macondo oil spill. Substantial new information that alters the impact conclusion for archaeological resources presented in MMS (2007b, 2008) has come to light as a result of BOEM-sponsored studies and industry surveys. Specifically, evidence of damage to significant cultural resources (i.e., historic shipwrecks) has been shown to have occurred because of an incompleteknowledge of seafloor conditions in lease areas >200 m (656 ft) deep that have been exempted from highresolution surveys. Since significant historic shipwrecks have recently been discovered outside the previously designated high-probability areas (some of which show evidence of impacts from permitted activities prior to their discovery), a survey is now required for exploration and development projects.

The lease area is not on the list of OCS blocks with a high potential for historic shipwrecks (BOEM, 2012c). A total of 24 unidentified sonar contacts was recorded during the archaeological assessment of the lease area; these sonar contacts were not recommended for archaeological avoidance or investigation, and the assessment area was interpreted to be absent of potential archaeological resources (C & C Technologies, Inc., 2012).

ExxonMobil will abide by the applicable requirements of NTL 2005-G07, which stipulate that work be stopped at the project site if any previously undetected archaeological resource is discovered after work has begun until appropriate surveys and evaluations have been completed.Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect shipwrecks. Impacts of a large oil spill (WCD) are the only IPFs considered. A small fuel spill would not affect shipwrecks because the oil would float and dissipate on the sea surface.

Impacts of a Large Oil Spill (WCD)

MMS (2007b) estimated that a severe subsurface blowout could resuspend and disperse sediments within a 300-m (984-ft) radius. Because there are no historic shipwrecks in the lease area, this impact would not
be relevant.

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect archaeological sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 35 km (22 miles) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact shipwreck sites beyond the 300-m (984-ft) radius estimated by MMS (2007a, 2008), depending on its extent, trajectory, and persistence. If oil from a subsea spill should come into contact with wooden shipwrecks on the seafloor, it could adversely affect their condition or preservation. Should there be any indication that potential shipwreck sites could be affected, in accordance with NTL 2005-G07 ExxonMobil will immediately halt operations, take steps to ensure that the site is not disturbed in any way, and contact the BOEM Regional Supervisor, Leasing and Environment, within 48 hours of its discovery. ExxonMobil would cease all operations within 305 m (1,000 ft) of the site until the Regional Supervisor provides instructions on steps to take to assess the site’s potential historic significance and protect it.

A spill entering shallow coastal waters could conceivably contaminate an undiscovered shipwreck site. As noted by MMS (2007b), should an oil spill contact a coastal historic site, such as a fort or a lighthouse, the major impact would be a temporary, reversible visual impact from oil contact and contamination of the
site and its environment.

C.6.2 Prehistoric Archaeological Sites

Available evidence suggests that sea level in the northern Gulf of Mexico was at least 91 m (300 ft), and possibly as much as 130 m (427 ft), lower than present sea level during the period 20,000 to 17,000 years Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern Gulf reached its present stand around 3,500 years B.P. (Pearson et al., 1986).

During periods that the continental shelf was exposed above sea level, the area was open to habitation by prehistoric peoples. The advent of early man into the Gulf of Mexico region is currently accepted to be around 12,000 years B.P. (Aten, 1983). The sea-level curve for the northern Gulf of Mexico proposed by Coastal Environments, Inc. suggests that sea level at 12,000 years B.P. would have been approximately 45 to 60 m (148 to 197 ft) below the present-day sea level (Coastal Environments, Inc., 1977, 1982). On this basis, the continental shelf shoreward of the 45- to 60-m (148- to 197-ft) bathymetric contours has potential for prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the depth of sea level and the entry date of prehistoric man into North America, the MMS adopted the 60-m (197-ft) water depth as the seaward extent for archaeological site potential in Gulf of Mexico region.

With a water depth of approximately 1,937 m (6,354 ft), the lease area is well beyond the 60-m (197-ft) depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric archaeological resources because the oil would float and dissipate on the sea surface.Impacts of a Large Oil Spill (WCD)

Because prehistoric archaeological sites are not found in the lease area, they would not be affected by the physical effects of a subsea blowout. The MMS (2007b) estimates that a severe subsurface blowout could resuspend and disperse sediments within a 300-m (984-ft) radius.

Along the northern Gulf Coast, prehistoric sites occur frequently along the barrier islands and mainland coast and along the margins of bays and bayous (MMS, 2007b). If a spill did reach a prehistoric site along these shorelines it could coat fragile artifacts or site features and compromise the potential for radiocarbon dating organic materials in a site (although other dating methods are available and it is possible to decontaminate an oiled sample for radiocarbon dating). Coastal prehistoric sites could also be damaged by spill cleanup operations (e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site features). BOEM (2012a) notes that some unavoidable direct and indirect impacts on coastal historic resources could occur resulting in the loss of information.

C.7 Coastal Habitats and Protected Areas

Coastal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities are described in lease sale EISs (MMS, 2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), and in a literature review by Collard and Way (1997). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. Generally, most of the northeastern Gulf is fringed by barrier beaches, with wetlands and/or submerged seagrass beds occurring in sheltered
areas behind the barrier islands and in estuaries.

Due to the distance from shore, the only IPF associated with routine activities in the lease area that potentially may affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area relates to support vessel traffic. The support bases at Port Fourchon, Louisiana, are not in wildlife refuges or wilderness areas. Potential impacts of support vessel traffic are addressed briefly below.

A small fuel spill in the lease area would be unlikely to affect coastal habitats, as the lease area is 261 km (162 miles) from the nearest shoreline (Louisiana). As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of Support Vessel Traffic

For OCS activities in general, support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Support operations, including crew boats and supply boats as detailed in EP Section 14, may have a minor incremental impact on coastal habitats or protected areas. Impacts will be minimized by following the speed and wake restrictions in harbors and
channels.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on coastal habitats are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. For this EP, there are no unique site-specific issues with respect to coastal habitats.

The revised OSRA modeling summarized in Table 3 predicts that during winter there is a 17% probability of oil from a spill in the lease area reaching shorelines in Texas within 120 days, and a 14% probability in spring of oil reaching Louisiana shorelines within 120 days.The shorelines within the geographic range predicted by the OSRA modeling ( Table 3 ) include extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered areas behind the barrier islands and in estuaries. NWRs and other protected areas along the coast are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012b) and ExxonMobil’s OSRP. Coastal and near coastal wildlife refuges, wilderness areas, and State and National parks within the geographic range of the potential shoreline contacts after 120 days are presented in Table 6

.

Table 6. Wildlife refuges, wilderness areas, and State and National parks within the geographic range of

the potential shoreline contacts after 120 days (From: BOEM, 2012b).

County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Cameron County, Texas Laguna Atascosa National Wildlife Refuge

Padre Island National Seashore

Isla Blanca Park Andy Bowie County Park Laguna Madre Estuarine and Coastal Marine Area

Willacy County, Texas Lower Rio Grande Valley National Wildlife Reserve Laguna Atascosa National Wildlife Reserve

Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Kenedy County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Kleberg County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Nueces County, Texas Laguna Madre Estuarine and Coastal Marine Area Mustang Island State Park Lake Corpus Christi State Park

Port Aransas Park

Mission-Aransas National Estuarine Research Reserve

Aransas County, Texas Mission-Aransas National Estuarine Research Reserve Aransas National Wildlife Refuge

Goose Island State Park

Calhoun County, Texas Mission-Aransas National Estuarine Research Reserve Aransas National Wildlife Refuge Matagorda Island State Park Guadalupe Delta Wildlife Management Area

Welder Flats Coastal Preserve

Matagorda County, Texas Big Boggy National Wildlife Refuge Aransas National Wildlife Refuge Mad Island Wildlife Management Area San Bernard National Wildlife Refuge

Brazoria County, Texas San Bernard National Wildlife Refuge Peach Point Wildlife Management Area Brazoria National Wildlife Refuge Christmas Bay Coastal Preserve and Christmas Bay State Park

Galveston County, Texas Galveston Island State Park Brazoria National Wildlife Refuge Apffel Park

Seawolf Park

Old Fort Travis Park Atkinson Island Wildlife Management Area

Ft. Anahuc Park Anahuac National Wildlife RefugeCounty or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park McFaddin National Wildlife Refuge

Jefferson County, Texas McFaddin National Wildlife Refuge

Sea Rim State Park Murphree Wildlife Management Area Texas Point National Wildlife Refuge

Cameron Parish, Louisiana Sabine National Wildlife Refuge Cameron Prairie National Wildlife Refuge Lacassine National Wildlife Refuge

Little Pecan Island Natural Area

Peveto Woods Natural Area Lower Neches Wildlife Management Area Rockefeller Wildlife Management Area

Vermilion Parish, Louisiana Louisiana Rockefeller Wildlife Management Area Paul J. Rainey Wildlife Management Area

Plaquemines Parish, Louisiana Salvador Wildlife Management Area

Jean Lafitte National Historical Park and Preserve Delta National Wildlife Refuge Pass-a-Loutre Wildlife Management Area Breton National Wildlife Refuge

St. Bernard State ParkThe level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics,

the geographic location of the landfall, and the weather and oceanographic conditions at the time (MMS, 2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil-and-water mousse, or tarballs (MMS, 2007b). Oil is generally deposited on beaches in lines defined by wave action at the time of landfall. Oil that remains on the beach will thicken as its volatile components are lost. Thickened oil may form tarballs or aggregations that incorporate sand, shell, and other materials into its mass. Tar may be buried to varying depths under the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up manually, mechanically, or both. Some oil can remain on the beach at varying depths and may persist for several years as it slowly biodegrades and volatilizes.

Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil contacting wetlands, approximately 2.7 ha (6.7 ac) of wetland vegetation will experience dieback. Thirty percent of these damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. About 15% of the contacted wetlands are expected to be converted permanently to open-water habitat. The critical concentration of oil is that concentration above which impacts to wetlands will be long-term and recovery will take longer than two growing seasons, and which causes plant mortality and some permanent wetland loss. Critical concentrations of various oils are expected to vary broadly for wetland types and wetland plant species. Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direct impacts of oil, cleanup activities in marshes may accelerate rates of erosion and retard recovery rates, which have been reported to require from years to decades following a spill (MMS, 2007b; BOEMRE, 2011a; BOEM, 2012b).

C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEM has reexamined the analysis for recreational and commercial fishing presented in MMS (2007b, 2008) based on additional information and in consideration of the Macondo spill. No new information was found that would alter the potential impacts on commercial fishing (BOEMRE, 2011a; BOEM, 2012b).

The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the project area, primarily during spring and summer. In August 2000, the Federal government closed two areas in the northeastern Gulf of Mexico to longline fishing (65 FR 47214, 1 August 2000). The lease is outside of the closure areas.

Longline gear consists of monofilament line deployed from a moving vessel and generally allowed to drift for 4 to 5 hours (Continental Shelf Associates, Inc., 2002). As the mainline is put out, baited leaders and buoys are clipped in place at regular intervals. It takes 8 to 10 hours to deploy a longline and about the same time to retrieve it. Longlines are often set near oceanographic features such as fronts or downwellings, with the aid of sophisticated on-board temperature sensors, depth finders, and positioning equipment. Vessels typically are 10 to 30 m (33 to 98 ft) long, and their trips last from about 1 to 3 weeks. The main Gulf of Mexico homeports for longlining vessels are in Louisiana (Dulac and Venice) and Florida (Destin, Madeira Beach, and Panama City).

It is unlikely that any commercial fishing activity other than longlining occurs at or near the project area. Benthic species targeted by commercial fishers occur on the upper continental slope, well inshore of the project area. Royal red shrimp ( **Pleoticus robustus** ) are caught by trawlers in water depths of about 250 to 550 m (820 to 1,804 ft). Tilefishes (primarily **Lophalotilus chamaeleonticeps** ) are caught by bottom longlining in water depths from about 165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002).

Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) (Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum rigs offshore Texas and Louisiana. Due to the distance from shore, it is unlikely that recreational fishing activity is occurring in the lease area.

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and lights). Two types of potential accidents are also addressed below – a small fuel spill and a large oil spill (WCD).

Impacts of Drilling Rig Presence

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For example, in January 1999, a portion of a pelagic longline snagged on the acoustic Doppler current profiler of a drillship working inthe Gulf of Mexico (Continental Shelf Associates, Inc., 2002). The line was removed without incident.

Generally, longline fishers use radar and are aware of offshore structures and ships when placing their sets. Therefore, little or no impact on pelagic longlining is expected.

Because it is unlikely that any recreational fishing activity is occurring in the project area, no adverse impacts are anticipated. Other factors such as effluent discharges are likely to have negligible impacts on commercial or recreational fisheries due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section 9 provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Pelagic longlining activities in the lease area, if any, could be interrupted in the event of a small fuel spill. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and weather conditions. Fishing activities could be interrupted due to the activities of response vessels operating in the lease area. A small fuel spill would not affect coastal water quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on fishing activities are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012b) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to this activity.

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of Mexico could be interrupted in the event of a large oil spill. A spill may or may not result in fishery closures, depending on the duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of spill response measures. The recent Macondo spill provides information about the maximum potential extent of fishery closures in the event of a large oil spill in the Gulf of Mexico (NMFS, 2010d). At its peak on 12 July 2010, closures encompassed 217,821 km 2 (84,101 mi 2 ), or 34.8% of the U.S. Gulf of Mexico EEZ.

C.8.2 Public Health and Safety

There are no IPFs associated with routine operations that are expected to affect public health and safety. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will potentially alleviate the potential for impacts. EP Section 9 provides detail on spill response measures.

A small fuel spill would not have any impacts on public health and safety because it would affect only a small area of the open ocean 261 km (162 miles) from the nearest shoreline (Louisiana) and nearly all of the diesel fuel would evaporate or disperse naturally within 24 hours. Response crews would be equipped with appropriate safety equipment to avoid injury and health effects. A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill (WCD)

In the event of a large spill from a blowout, the main safety and health concerns are those of the offshore personnel involved in the incident and those responding to the spill. The drilling rig maintains a Shipboard Oil Pollution Emergency Plan as required under MARPOL 73/78.

Depending on the spill rate and duration, the physical/chemical characteristics of the oil, meteorological and oceanographic conditions at the time, and the effectiveness of spill response measures, the public could be exposed to oil on the water and along the shoreline, including skin contact or breathing VOCs. Crude oil is a highly flammable material, and any smoke or vapors from a crude oil fire can cause irritation, and in large quantities may pose a health hazard.Data from the recent Macondo spill provide relevant information about the types of health issues that may

occur in the event of a large oil spill (Centers for Disease Control and Prevention, 2010a). Wildlife cleaning and rehabilitation workers have reported concerns including scrapes and cuts, itchy or red skin or rash, and symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or back pain was also reported by some wildlife-cleaning workers. Personnel working on offshore vessels or providing direct oversight to offshore vessels, including USCG personnel, civilian contractors, and other responders who were exposed to oil and dispersants, had a 7 to 12 times higher prevalence of upper respiratory symptoms and cough than those not exposed (Centers for Disease Control and Prevention, 2010b). Another potential occupational hazard for spill response workers in general was heat stress from work in a hot and humid environment. Initial symptoms from cleanup workers who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H 2 S, e.g., headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest pain (Solomon and Janssen, 2010).

C.8.3 Employment and Infrastructure

There are no IPFs associated with routine operations that are expected to affect employment and infrastructure. The project involves drilling with support from existing shorebase facilities in Louisiana. No new or expanded facilities will be constructed, and no new employees are expected to move permanently into the area. The project will have a negligible impact on socioeconomic conditions such as local employment, existing offshore and coastal infrastructure (including major sources of supplies, services, energy, and water), and minority and lower income groups. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section 9 provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill that is dissipated within a few days would have little or no economic impact, as the spill response would use existing facilities, resources, and personnel.

Impacts of a Large Oil Spill (WCD)

Potential socioeconomic impacts of an oil spill are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to employment and coastal infrastructure. A large spill could cause economic impacts in several ways: it could result in extensive fishery closures that put fishermen out of work; it could result in temporary employment as part of the response effort; it could result in adverse publicity that affects employment in coastal recreation and tourism industries; and it could result in another suspension of OCS drilling activities, including service and support operations that are an important part of local economies.

In addition to the analyses presented by MMS (2007b, 2008) and BOEM (2012b), a recent study explored the economic impacts of the Macondo spill on oil and gas industry employment due to suspension of deepwater drilling (Inter-Agency Economic Report, 2010). The study indicates that during the moratorium, the number of oil industry workers in the Gulf of Mexico fell by about 2,000 and may have indirectly caused a temporary loss of 8,000 to 12,000 jobs along the Gulf Coast. Total spending by drilling operators is estimated to have declined by $1.8 billion over a 6-month period; this direct reduction in spending affected employment in the industries that supply the Gulf drilling industry and in all other industries affected by declines in consumer and business spending (Inter-Agency Economic Report, 2010).

C.8.4 Recreation and Tourism

The BOEM has reexamined the analyses for recreation and tourism presented in MMS (2007b, 2008) based on additional information and in consideration of the Macondo oil spill event. No new information was found that would alter the potential impacts on recreation and tourism (BOEMRE, 2011a; BOEM, 2012b).

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas would not be affected by any routine activities because of the distance from shore. Compliance with NTL 2012- BSEE-G01 will minimize the chance of trash or debris being lost overboard from the drilling rig and subsequently washing up on beaches.Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will potentially help mitigate and reduce the potential for impacts. EP Section 9 provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are no known recreational or tourism activities occurring in the lease area, and as explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of a Large Oil Spill (WCD)

Potential impacts of an oil spill on recreation and tourism are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to these impacts.

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate including the effectiveness of response measures. A large spill that reached coastal waters and shorelines could adversely affect recreation and tourism by contaminating beaches and wetlands, resulting in negative publicity that encourages people to stay away. Based on the revised OSRA modeling (BOEM, 2012b) as summarized in
Section A.9.3 ( Table 3 ), there is a 17% probability in winter of oil from a spill in the lease area reaching shorelines in Texas and a 14% chance in spring of contacting shorelines in Louisiana within 120 days.

In addition to the analysis presented by MMS (2007b; BOEMa,b,d), recent and ongoing studies have explored the economic impacts of the Macondo spill including tourism and "brand" damage (IEM, 2010; Oxford Economics, 2010). The U.S. Travel Association has estimated the economic impact of the Macondo spill on tourism across the Gulf Coast over a 3-year period at $22.7 billion (Oxford Economics, 2010).

C.8.5 Land Use

Land use along the northern Gulf Coast is discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b,) and the current Programmatic EIS (BOEM, 2012d). There are no routine IPFs potentially affecting land use. The project will use existing onshore support facilities in Louisiana. The land use at the existing shorebase is industrial. The project will not involve any new construction or changes to existing land use and therefore will not have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and services including scarce coastal resources, will represent a small fraction of the level of activity occurring at the shorebases.

A large oil spill (WCD) is the only relevant IPF. A small fuel spill would not have any impacts on land use, as the response would be staged out of existing shorebases and facilities.

Impacts of a Large Oil Spill (WCD)

The initial response for a large oil spill would be staged out of existing facilities, with no effect on land use. A large spill could have limited temporary impacts on land use along the coast if additional staging areas were needed. For example, during the Macondo spill, temporary staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response and cleanup efforts. In the event of a large spill in the lease area, similar temporary staging areas could be needed. These areas would eventually return to their original use as the response is demobilized.

C.8.6 Other Marine Uses

The lease area is not located within any USCG-designated fairway or shipping lane or Military Warning Area. ExxonMobil will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

There are no IPFs from routine project activities that are likely to affect other marine uses of the lease area. A large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not have any impacts on other marine uses because spill response activities would be mainly within the lease area and the duration would be
brief.Impacts of a Large Oil Spill (WCD)

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The block is not located within any USCG-designated fairway or shipping lane or Military Warning Area. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations. ExxonMobil will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

In the event of a large spill requiring numerous vessels in the area, coordination would be required to ensure that no anchoring or seafloor-disturbing activities occur near the existing pipelines and flowlines.



# D. Environmental Hazards

D.1 Geologic Hazards

The geohazard assessment conducted by Gardline Surveys Inc. (2010) concluded that the wellsite is free of any significant geological hazards and suitable for the proposed activities. See EP Section 3 for supporting geological and geophysical information.

D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed activities. Extreme weather, including high winds, strong currents, and large waves, was considered in the design criteria for the drilling rigs under consideration for this project. High winds and limited visibility during a severe storm could disrupt support activities (vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes. In the event of a hurricane, procedures as outlined in the drilling contractor’s Hurricane Evacuation Plan would be adhered to.

D.3 Currents and Waves

Metocean conditions such as sea states, wind speed, ocean currents, etc. will be continuously monitored. Under most circumstances, physical oceanographic conditions are not expected to have any effect on the proposed activities. Strong currents (e.g., caused by Loop Current eddies and intrusions) and large waves were considered in the design criteria for the drillship under consideration for this project. High waves during a severe storm could disrupt support activities (i.e., vessel and helicopter traffic) and make it necessary to suspend some activities on the drillship for safety reasons until the storm or weather event passes.



# E. Alternatives

No formal alternatives were evaluated in this EIA for an EP. However, various technical and operational options, including the location of the wellsite and the selection of a drilling unit, were considered by ExxonMobil in developing the proposed action.



# F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and BOEM lease stipulations and NTLs. The project will comply with all applicable Federal, State, and local requirements concerning air pollutant emissions, discharges to water, and solid waste disposal. All project activities will be conducted under guidance by ExxonMobil’s OSRP and will include the measures described in EP Section 9.

# G. Consultation

No persons or agencies were consulted during the preparation of this EIA.



# H. Preparers

The EIA was prepared by CSA Ocean Sciences Inc. Contributors included:

• C. Chandool, Ph.D. (Senior Scientist);

• C. Kalloo (Senior Scientist);

• M. John Thompson (Senior Scientist);

• Neal Phillips, Ph.D. (Senior Scientist);

• Keith VanGraafeiland (GIS/Remote Sensing Specialist);

• Kristen L. Metzger (Library and Information Services Director); and

• Melody B. Powell (Technical Editor).



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### S ECTION 19: ADMINISTRATIVE INFORMATION

Exempted Information Description (Public Information Copies Only)

The following attachments were excluded from the public information copies of this plan:

 Section 1: OCS Plan Information form – Bottom hole locations & proposed total depth

 Section 2: Blowout Scenario – confidential information for NTL 2010-N06 calculation

 Section 3: Geologic Description

 Section 3: Structure Contour Maps

 Section 3: Interpreted 2D or 3D seismic line(s)

 Section 3: Cross Section(s)

 Section 3: High-Resolution Seismic Lines & Top Hole Progs

 Section 3: Stratigraphic Column with Time vs. depth table

 Section 3: Power Spectrums and Tophole Progs



### Bibliography

• **3D Geohazard Assessment, Walker Ridge, Blocks 191-195, 235-239, 279-283, & 323-327, Maui Prospect** (Gardline, October 2010)

• **Archaeological Assessment Report, Blocks 237, 238, 281, 282, and Vicinity, Walker Ridge Area, Gulf of Mexico (C&C Project No. 120009)** 

• Exxon Mobil Regional Oil Spill Response Plan - Offshore Operations, Appendix H, Sept. 2011

• CSA Environmental Impact Analysis for Walker Ridge 282, April 2013